When should safety valves be sealed? Regular check
RUSSIAN JOINT STOCK COMPANY OF ENERGY AND ELECTRIFICATION "UES OF RUSSIA"
DEPARTMENT OF DEVELOPMENT STRATEGY AND SCIENTIFIC AND TECHNICAL POLICY
INSTRUCTIONS FOR ORGANIZING OPERATION, PROCEDURE AND TIMELINES FOR CHECKING SAFETY DEVICES OF BOILERS OF THERMAL POWER PLANTS
RD 153-34.1-26.304-98
Enters into force from 01.10.99.
Developed Open joint stock company"Company for setting up, improving technology and operating power plants and networks of ORGRES"
Executor V.B. KAKUZIN
Agreed with Gosgortekhnadzor of Russia 12/25/97
Approved Department of Development Strategy and Scientific and Technical Policy of RAO "UES of Russia" 01/22/98
First Deputy Chief D.L. BERSENEV
1. GENERAL PROVISIONS
1.1. This Instruction applies to safety devices installed on thermal power plant boilers.
1.2. The instructions contain the basic requirements for the installation of safety devices and determine the procedure for their regulation, operation and maintenance.
Appendix 1 sets out the basic requirements for boiler safety devices contained in the rules of the Gosgortekhnadzor of Russia and GOST 24570-81, provides technical characteristics and design solutions for boiler safety devices, and recommendations for calculating the capacity of safety valves.
The purpose of the Instruction is to help improve the safety of operation of thermal power plant boilers.
1.3. When developing the Instructions, the guidelines of the Gosgortekhnadzor of Russia, , , , , and data on operating experience of safety devices of thermal power plant boilers were used.
1.4. With the publication of this Instruction, the "Instructions for organizing the operation, procedure and timing of testing pulse safety devices of boilers with operating steam pressure from 1.4 to 4.0 MPa (inclusive): RD 34.26.304-91" and "Instructions for organizing operation, procedure and timing of inspection of impulse safety devices of boilers with steam pressure above 4.0 MPa: RD 34.26.301 -91".
1.5. The following abbreviations are adopted in the Instructions;
PU- safety device:
PC- direct acting safety valve;
RGPC- direct-acting lever-load safety valve;
PPK- direct acting spring safety valve;
IPU- impulse safety device;
Civil Procedure Code- main safety valve;
IR- pulse valve;
CHZEM- JSC "Chekhov Power Engineering Plant";
TKZ- PA "Krasny Kotelshchik"
1.6. The methodology for calculating the throughput capacity of boiler safety valves, forms of technical documentation for safety devices, basic terms and definitions, designs and technical characteristics of safety valves are given in Appendices 2-5.
2. BASIC REQUIREMENTS FOR PROTECTING BOILERS FROM INCREASING PRESSURE ABOVE THE ALLOWABLE VALUES
2.1. Each steam boiler must be equipped with at least two safety devices.
2.2. The following may be used as safety devices on boilers with pressures up to 4 MPa (40 kgf/cm2) inclusive:
direct-acting lever-weight safety valves;
Direct acting spring safety valves.
2.3. Steam boilers with steam pressure over 4.0 MPa (40 kgf/cm2) must be equipped only with pulse-safety devices with an electromagnetic drive.
2.4. Passage diameter (conditional) of lever-load and spring valves direct acting and pulse valves IPU must be at least 20 mm.
2.5. The nominal diameter of the tubes connecting the pulse valve to the IPU GPK must be at least 15 mm.
2.6. Safety devices must be installed:
a) in steam boilers with natural circulation without a superheater - on the upper drum or steam steamer;
b) in direct-flow steam boilers, as well as in boilers with forced circulation - on the outlet manifolds or the outlet steam pipeline;
c) in hot water boilers - on the output collectors or drum;
d) in intermediate superheaters, all safety devices are on the steam inlet side;
e) in water-switched economizers - at least one safety device at the water outlet and water inlet.
2.7. If the boiler has a non-switchable superheater, part of the safety valves with a capacity of at least 50% of the total capacity of all valves must be installed on the outlet manifold of the superheater.
2.8. On steam boilers with an operating pressure of more than 4.0 MPa (40 kgf/cm2), pulse safety valves (indirect action) must be installed on the outlet manifold of a non-switchable superheater or on the steam line to the main shut-off valve, while in drum boilers for 50% of the valves Based on the total throughput, steam selection for pulses should be made from the boiler drum.
If there is an odd number of identical valves, it is allowed to select steam for pulses from the drum for no less than 1/3 and no more than 1/2 of the valves installed on the boiler.
On block installations, if valves are placed on the steam pipeline directly next to the turbines, it is allowed to use superheated steam for impulses of all valves, while for 50% of the valves an additional electrical impulse must be supplied from a contact pressure gauge connected to the boiler drum.
If there is an odd number of identical valves, it is allowed to supply an additional electrical impulse from a contact pressure gauge connected to the boiler drum for no less than 1/3 and no more than 1/2 of the valves.
2.9. In power units with intermediate steam superheating, safety valves with a capacity of at least the maximum amount of steam entering the intermediate superheater must be installed after the turbine high-pressure cylinder (HPC). If there is a shut-off valve behind the HPC, additional safety valves must be installed. These valves must be calculated taking into account both the total capacity of the pipelines connecting the reheater system with higher pressure sources that are not protected by their safety valves at the entrance to the reheat system, and possible steam leaks that may occur if the high pressure steam and steam pipes are damaged. gas-steam heat exchangers steam temperature regulation.
2.10. The total capacity of the safety devices installed on the boiler must be at least the hourly steam output of the boiler.
Calculation of the throughput capacity of boiler safety devices according to GOST 24570-81 is given in Appendix 1.
2.11. Safety devices must protect boilers, superheaters and economizers from increasing their pressure by more than 10%. Exceeding the steam pressure when the safety valves are fully open by more than 10% of the calculated value can only be allowed if this is provided for in the strength calculations of the boiler, superheater, or economizer.
2.12. The design pressure of safety devices installed on cold reheat pipelines should be taken as the lowest design pressure for low-temperature elements of the reheat system.
2.13. Sampling of the medium from the branch pipe or pipeline connecting the safety device to the protected element is not allowed.
2.14. The installation of shut-off devices on the steam supply line to the safety valves and between the main and pulse valves is not allowed.
2.15. To control the operation of the IPU, it is recommended to use an electrical circuit developed by the Teploelektroproekt Institute (Fig. 1), which provides for pressing the plate to the seat at normal pressure in the boiler due to the constant flow of current around the winding of the closing electromagnet.
For IPU installed on boilers with a nominal excess pressure of 13.7 MPa (140 kgf/cm 2) and below, by decision of the chief engineer of the thermal power plant, operation of the IPU is allowed without constant current flowing around the winding of the closing electromagnet. In this case, the control circuit must ensure that the IR is closed using an electromagnet and turned off 20 s after the IR is closed.
The IR electromagnet control circuit must be connected to backup source direct current.
In all cases, only return keys should be used in the control scheme.
2.16. Devices should be installed in the connecting pipes and supply pipelines to prevent sudden changes in wall temperature (thermal shocks) when the valve is activated.
2.17. The internal diameter of the supply pipe must be no less than the maximum internal diameter of the supply pipe of the safety valve. The pressure drop in the supply pipeline to direct-acting safety valves should not exceed 3% of the valve opening pressure. In the supply lines of safety valves controlled by auxiliary devices, the pressure drop should not exceed 15%.
2.18. Steam from safety valves must be vented to a safe location. The internal diameter of the outlet pipe must be no less than the largest internal diameter of the outlet pipe of the safety valve.
2.19. The installation of a noise suppression device on the outlet pipeline should not cause a reduction in the capacity of the safety devices below the value required by safety conditions. When the outlet pipeline is equipped with a noise-attenuating device, a fitting for installing a pressure gauge must be provided immediately behind the valve.
2.20. The total resistance of the outlet pipelines, including the noise suppression device, must be calculated so that when the flow rate of the medium through it is equal to the maximum throughput of the safety device, the back pressure in the valve outlet pipe does not exceed 25% of the response pressure.
2.21. The outlet pipelines of safety devices must be protected from freezing and equipped with drains to drain condensate that accumulates in them. Installation locking devices on drains is not allowed.
2.22. The riser (a vertical pipeline through which the medium is discharged into the atmosphere) must be securely fastened. In this case, the static and dynamic loads that arise when the main valve operates must be taken into account.
2.23. Temperature expansion compensation must be ensured in the safety valve pipelines. The fastening of the body and pipeline of safety valves must be designed taking into account static loads and dynamic forces that arise when the safety valves operate.
Rice. 1. Electrical circuit of the IPU
Note - The diagram is made for one pair of IPCs
3. INSTRUCTIONS FOR INSTALLATION OF SAFETY DEVICES
3.1. Valve storage rules
3.1.1. Safety devices must be stored in places that prevent moisture and dirt from entering the internal cavities of the valves, corrosion and mechanical damage to parts.
3.1.2. Pulse valves with an electromagnetic drive must be stored in dry, enclosed areas free of dust and vapors that could cause destruction of the electromagnet windings.
3.1.3. The valves have a shelf life of no more than two years from the date of shipment from the manufacturer. More if necessary long-term storage products must be re-preserved.
3.1.4. Loading, transporting and unloading of valves must be carried out in compliance with precautions to ensure they are not broken or damaged.
3.1.5. Subject to the above transportation and storage rules, the presence of plugs and the absence of external damage, the valves can be installed on workplace without revision.
3.1.6. If transportation and storage rules are not followed, the valves should be inspected before installation. The issue of compliance of the storage conditions for valves with the requirements of the normative and technical documentation should be decided by a commission of representatives of the operational and repair departments of the thermal power plant and the installation organization.
3.1.7. When inspecting valves, you should check:
condition of the sealing surfaces of the valve.
After inspection, the sealing surfaces must be clean R a = 0.32;
condition of gaskets;
condition of the seal packing of the servomotor piston.
If necessary, install new packing from pre-compressed rings. Based on the CHZEM tests, a combined seal consisting of a set of rings can be recommended for installation in the GPC servo drive chamber: two packages of rings made of graphite and metal foil and several rings made of thermally expanded graphite. (The seal is manufactured and supplied by JSC Unikhimtek, 167607, Moscow, Michurinsky Prospekt, 31, building 5);
the condition of the piston working jacket in contact with the stuffing box; traces of possible corrosion damage to the shirt must be eliminated;
condition of the threads of fasteners (absence of nicks, burrs, chipping of threads);
condition and elasticity of springs,
After assembly, you should check the ease of movement of the moving parts and compliance of the valve stroke with the requirements of the drawing.
3.2. Placement and installation
3.2.1. Impulse safety devices must be installed in enclosed spaces.
The valves may be operated under the following environmental limits:
when using valves intended for delivery to countries with temperate climate: temperature - +40°C and relative humidity - up to 80% at a temperature of 20°C;
when using valves intended for delivery to countries with tropical climates; temperature - +40°C;
relative humidity - 80% at temperatures up to 27°C.
3.2.2. The products included in the IPU kit must be installed in places that allow for their maintenance and repair, as well as assembly and disassembly on site without cutting out from the pipeline.
3.2.3. Installation of valves and connecting pipelines must be carried out according to working drawings developed by the design organization.
3.2.4. The main safety valve is welded to the fitting of the manifold or steam line with the stem strictly vertically upward. Deviation of the rod axis from the vertical is allowed no more than 0.2 mm per 100 mm of valve height. When welding a valve into a pipeline, it is necessary to prevent burr, splashes, and scale from entering their cavity and pipelines. After welding, the welds are subject to heat treatment in accordance with the requirements of the current instructions for the installation of pipeline equipment.
3.2.5. The main safety valves are attached with the paws available in the design of the products to a support, which must absorb the reactive forces that arise when the IPU is triggered. The exhaust pipes of the valves must also be securely fastened. In this case, any additional stress must be eliminated in the connection between the exhaust and the connecting flanges of the exhaust pipes. Constant drainage must be organized from the lowest point.
3.2.6. Pulse valves for fresh steam and reheat steam produced by LMZ, mounted on a special frame, must be installed on sites that are convenient for maintenance and protected from dust and moisture.
3.2.7. The pulse valve must be installed on the frame so that its stem is strictly vertical in two mutually perpendicular planes. The IR lever with a load and an electromagnet core suspended on it should not have distortions in the vertical and horizontal planes. To avoid jamming when opening the IR, the lower electromagnet must be located relative to the IR so that the centers of the holes in the core and lever are on the same vertical; the electromagnets must be located on the frame so that the axes of the cores are strictly vertical and located in a plane passing through the axes of the rod and the IR lever.
3.2.8. To ensure a tight fit of the IR plate on the saddle, the bar on which the clamp of the upper electromagnet rests must be welded so that the gap between the lower plane of the lever and the clamp is at least 5 mm.
3.2.9. When selecting pulses on an IR and an electric contact pressure gauge (ECM) from the same element on which the GPC is installed, the pulse sampling points must be at such a distance from the GPC that when it is triggered, the disturbance of the steam flow does not affect the operation of the IR and ECM (at least 2 m). The length of the impulse lines between the impulse and main valves should not exceed 15 m.
3.2.10. Electrical contact pressure gauges must be installed at the boiler service level. Acceptable Maximum temperature The ambient temperature in the ECM installation area should not exceed 60°C. Stop valve on the medium supply line to the ECM must be open and sealed during operation.
4. PREPARATION OF VALVES FOR OPERATION
4.1. The compliance of the installed valves with the requirements of the design documentation and section is checked. 3.
4.2. The tightness of the valve fasteners, the condition and quality of fit of the supporting surfaces of the prism of lever-load valves are checked: the lever and the prism must mate across the entire width of the lever.
4.3. The compliance of the actual stroke value of the hydraulic pump with the instructions of the technical documentation is checked (see Appendix 5).
4.4. In the GPK, reheat steam is moved by moving the adjusting nut along the stem to ensure a gap between its lower end and the upper end of the support disk, equal to the valve stroke.
4.5. For the reheat steam generator set produced by ChZEM, the screw of the throttle valve built into the cover is turned out by 0.7-1.0 turns,
4.6. The condition of the electromagnet cores is checked. They must be cleaned of old grease, rust, dust, washed with gasoline, ground and rubbed with dry graphite. The rod at the junction with the core and the core itself should not have distortions. The movement of the cores must be free.
4.7. The position of the damper screw of the electromagnets is checked. This screw should be screwed in so that it protrudes above the end of the electromagnet housing by approximately 1.5-2.0 mm. If the screw is completely screwed in, then when the armature rises, a vacuum is created under it, and with the electrical circuit de-energized, it is almost impossible to adjust the valve to operate at a given pressure. Over-tightening the screw will cause the core to move violently as it retracts, causing the sealing surfaces of the impulse valves to break.
5. ADJUSTING SAFETY DEVICES TO ACTIVATE AT A SET PRESSURE
5.1. Adjustment of safety devices to operate at a given pressure is carried out:
after installation of the boiler is completed;
after a major overhaul, if the safety valves were replaced or overhauled ( complete disassembly, grooving sealing surfaces, replacing chassis parts, etc.), and for PPK - in case of replacing a spring.
5.2. To adjust the valves, a pressure gauge with an accuracy class of 1.0, tested in the laboratory using a standard pressure gauge, must be installed in close proximity to them.
5.3. Safety valves are regulated at the valve installation site by raising the pressure in the boiler to the response pressure.
Adjustment of spring safety valves can be done on a steam bench with operating parameters, followed by a control check on the boiler.
5.4. The actuation of the valves during adjustment is determined by:
for IPU - at the moment of activation of the GPC, accompanied by impact and loud noise;
for direct-acting full-lift valves - by a sharp pop observed when the spool reaches the top position.
For all types of safety devices, operation is controlled by the beginning of the pressure drop on the pressure gauge.
5.5. Before adjusting the safety devices, you must:
5.5.1. Make sure that all installation, repair and adjustment work is stopped on the systems in which the steam pressure necessary for regulation will be created, on the safety devices themselves and on their exhaust pipelines.
5.5.2. Check the reliability of disconnecting systems in which pressure will increase from adjacent systems.
5.5.3. Remove all bystanders from the valve adjustment area.
5.5.4. Provide good lighting PU installation workplaces, service platforms and adjacent passages.
5.5.5. Establish two-way communication between valve adjustment points and the control panel.
5.5.6. Conduct instruction for shift and adjustment personnel involved in valve adjustment work.
Staff should be well aware design features subject to PU regulation and the requirements of the instructions for their operation.
5.6. Adjustment of direct-acting lever-load valves is carried out in the following sequence;
5.6.1. The weights on the valve levers are moved to their extreme position.
5.6.2. In the protected object (drum, superheater), a pressure is established that is 10% higher than the calculated (permitted) one.
5.6.3. The weight on one of the valves is slowly moved towards the body until the valve is activated.
5.6.4. After closing the valve, the position of the weight is fixed with a locking screw.
5.6.5. The pressure in the protected object rises again and the pressure value at which the valve operates is checked. If it differs from that set in paragraph 5.6.2, the position of the weight on the lever is adjusted and the correct operation of the valve is re-checked.
5.6.6. After the adjustment is completed, the position of the weight on the lever is finally fixed with a locking screw. To prevent uncontrolled movement of the load, the screw is sealed.
5.6.7. An additional weight is installed on the lever of the adjusted valve and the remaining valves are adjusted in the same sequence.
5.6.8. After completing the adjustment of all valves in the protected object, the operating pressure is established. Additional weights are removed from the levers. A record is made in the Maintenance and Operation Log of safety devices about the readiness of the valves for operation.
5.7. Adjustment of direct acting spring safety valves:
5.7.1. The protective cap is removed and the tension height of the spring h 1 is checked (Table 6).
5.7.2. The pressure value in the protected object is set in accordance with clause 5.6.2.
5.7.3. By turning the adjusting sleeve counterclockwise, the compression of the spring is reduced to the position at which the valve will operate.
5.7.4. The pressure in the boiler rises again and the pressure value at which the valve operates is checked. If it differs from that set according to clause 5.6.2, then the spring compression is adjusted and the valve is re-checked for operation. At the same time, the pressure at which the valve closes is monitored. The difference between the actuation pressure and the closing pressure should be no more than 0.3 MPa (3.0 kgf/cm2). If this value is greater or less, then the position of the upper adjusting sleeve must be adjusted.
For this:
For TKZ valves, unscrew the locking screw located above the cover and turn the damper bushing counterclockwise to reduce the drop or clockwise to increase the drop;
For the PPK and SPPK valves of the Blagoveshchensk Valve Plant, the pressure difference between the actuation and closing pressures can be adjusted by changing the position of the upper adjusting sleeve, which is accessed through a hole closed with a plug on the side surface of the body.
5.7.5. The height of the spring in the adjusted position is recorded in the Journal of Repair and Operation of Safety Devices and it is compressed to the value h 1 to be able to adjust the remaining valves. After completing the adjustment of all valves, the spring height recorded in the log in the adjusted position is set on each valve. To prevent unauthorized changes in the spring tension, a protective cap is installed on the valve, covering the adjusting sleeve and the end of the lever. The bolts securing the protective cap are sealed.
5.7.6. After the adjustment is completed, a record is made in the Maintenance and Operation Log of safety devices indicating that the valves are ready for operation.
5.8. Pulse safety devices with IR, equipped with an electromagnetic drive, are regulated to operate both from electromagnets and when the electromagnets are de-energized.
5.9. To ensure that the IPU is triggered by electromagnets, the ECM is configured:
5.9.1. The ECM readings are compared with the readings of a standard pressure gauge with a class of 1.0%.
5.9.2. The ECM is adjusted to turn on the opening electromagnet;
MPa,
where h is the correction for water column pressure
MPa,
here r is the density of water, kg/m3;
DN is the difference between the marks of the place where the impulse line is connected to the protected object and the place where the ECM is installed, m.
5.9.3. The ECM is adjusted to turn on the closing electromagnet:
MPa.
5.9.4. The limits of IR operation are marked on the ECM scale.
5.10. Adjusting the IR to operate at a given pressure with de-energized electromagnets is carried out in the same sequence as adjusting direct-acting lever-load valves:
5.10.1. The weights on the IR levers are moved to their extreme position.
5.10.2. The pressure in the boiler drum rises to the IPU response set point ( R av = 1.1 R b); on one of the IR loads connected to the boiler drum, the load moves towards the lever to a position at which the IPU is triggered. In this position, the load is fixed to the lever with a screw. After this, the pressure in the drum rises again and it is checked at what pressure the IPU is triggered. If necessary, the position of the load on the lever is adjusted. After adjustment, the weights on the lever are secured with a screw and sealed.
If more than one IR is connected to the boiler drum, an additional weight is installed on the lever of the adjusted valve to allow adjustment of the remaining IR connected to the drum.
5.10.3. A pressure equal to the response pressure of the IPU behind the boiler ( R av = 1.1 R R). In the manner prescribed in clause 5.10.2, it is regulated for the operation of the IPU, in which the steam on the IR is taken from the boiler.
5.10.4. After the adjustment is completed, the pressure behind the boiler is reduced to nominal and additional weights are removed from the IR levers.
5.11. Voltage is supplied to the electrical control circuits of the IPU. The valve control keys are set to the "Automatic" position.
5.12. The steam pressure behind the boiler is increased to the value at which the IPU should operate, and the opening of the gas pumps of all IPUs, the impulse to open which is taken behind the boiler, is checked locally.
When adjusting the IPU on drum boilers, the IPU control keys, triggered by a pulse behind the boiler, are set to the “Closed” position and the pressure in the drum rises to the IPU actuation set point. The operation of the GPK IPU, operating on an impulse from the drum, is checked locally.
5.13. Pulse-safety devices for reheat steam, which do not have shut-off elements behind them, are configured to operate after installation during the boiler firing for steam density. The procedure for setting the valves is the same as when setting the fresh steam valves installed behind the boiler (section 5.10.3).
If there is a need to adjust the reheat steam pulse valves after repairs, it can be done on a special stand. In this case, the valve is considered adjusted when the rise of the rod by the stroke value is recorded.
5.14. After checking the operation of the IPU, the control keys of all IPUs must be in the “Automatic” position.
5.15. After adjusting the safety devices, the shift supervisor must make an appropriate entry in the Maintenance and Operation Log of the safety devices.
6. PROCEDURE AND TIMELINES FOR CHECKING VALVES
6.1. Checking the proper operation of safety devices should be carried out:
when the boiler is stopped for scheduled repairs;
during boiler operation:
on pulverized coal boilers - once every 3 months;
on gas-oil boilers - once every 6 months.
During specified time intervals, the inspection should be timed to coincide with scheduled boiler shutdowns.
On boilers that are put into operation periodically, the check should be carried out during startup, if more than 3 or 6 months have passed, respectively, since the previous check.
6.2. Checking of the fresh steam IPU and reheat steam IPU, equipped with an electromagnetic drive, must be done remotely from the control panel with on-site response control, and the reheat steam IPU, which does not have an electromagnetic drive, by manually detonating the pulse valve at a unit load of at least 50% of the nominal load.
6.3. Testing of direct-acting safety valves is carried out at operating pressure in the boiler by alternately forcibly detonating each valve.
6.4. The inspection of safety devices is carried out by the shift supervisor (senior boiler operator) according to a schedule that is drawn up annually for each boiler based on the requirements of this Instruction, agreed with the operation inspector and approved by the chief engineer of the power plant. After the inspection, the shift supervisor makes an entry in the Maintenance and Operation Log of safety devices.
7. RECOMMENDATIONS FOR MONITORING THE CONDITION AND ORGANIZING REPAIR OF VALVES
7.1. Scheduled condition monitoring (inspection) and repair of safety valves are carried out simultaneously with the equipment on which they are installed.
7.2. Monitoring the condition of safety valves includes disassembling, cleaning and defective parts, checking the tightness of the valve, and the condition of the seal packing of the servo drive.
7.3. Condition monitoring and repair of valves must be carried out in a specialized valve workshop on special stands. The workshop must be equipped with lifting mechanisms, well lit, and have a water supply compressed air. The location of the workshop should ensure convenient transportation of the valves to the installation site.
7.4. Monitoring the condition and repairing valves must be carried out by a repair team that has experience in repairing valves and has studied the design features of valves and the principle of their operation. The team must be provided with working drawings of the valves, repair forms, spare parts and materials for their quick, high-quality repair.
7.5. In the workshop, valves are disassembled and parts are defective. Before fault detection, parts are cleaned of dirt and washed in kerosene.
7.6. When inspecting the sealing surfaces of the valve seat and plate parts, pay attention to their condition (absence of cracks, dents, marks and other defects). During subsequent assembly, the sealing surfaces must be rough R a = 0.16. The quality of the sealing surfaces of the seat and plate must ensure their mutual contact, which ensures the mating of these surfaces along a closed ring, the width of which is not less than 80% of the width of the smaller sealing surface.
7.7. When inspecting the jackets of the servo drive piston chamber and guides, pay attention that the ellipse of these parts does not exceed 0.05 mm per diameter. The roughness of surfaces in contact with the stuffing box must correspond to the cleanliness class R a = 0.32.
7.8. When inspecting the servo piston Special attention You should pay attention to the condition of the stuffing box. The rings must be tightly compressed together. There should be no damage to the working surface of the rings. Before assembling the valve, it should be well graphiteized.
7.9. The condition of the threads of all fasteners and adjusting screws must be checked. All parts with defective threads must be replaced.
7.10. You should check the condition of the coil springs, for which you should visually check the condition of the surface for cracks and deep scratches, measure the height of the spring in a free state and compare it with the requirements of the drawing, check the deviation of the spring axis from the perpendicular.
7.11. Repair and restoration of valve parts should be carried out in accordance with the current instructions for the repair of valves.
7.12. Before assembling the valves, check that the dimensions of the parts correspond to the dimensions specified in the form or working drawings.
7.13. Tightening the stuffing box rings in the piston chambers of the gas-piston chamber should ensure the tightness of the piston, but not impede its free movement.
8. ORGANIZATION OF OPERATION
8.1. Overall responsibility for technical condition, inspection and maintenance of safety devices is entrusted to the head of the boiler-turbine (boiler) shop on whose equipment they are installed.
8.2. The workshop order appoints persons responsible for checking valves, organizing their repair and maintenance, and maintaining technical documentation.
8.3. In the workshop, for each boiler, a log of repair and operation of safety devices installed on the boiler must be kept.
8.4. Each valve installed on the boiler must have a passport containing the following data;
valve manufacturer;
valve brand, type or drawing number;
nominal diameter;
serial number of the product;
operating parameters: pressure and temperature;
opening pressure range;
flow coefficient a, equal to 0.9 of the coefficient obtained on the basis of the valve tests;
calculated flow area;
for spring safety valves - the characteristics of the spring;
data on materials of main parts;
certificate of acceptance and conservation.
8.5. For each group of valves of the same type there must be: Assembly drawing, technical description and operating instructions.
9. SAFETY REQUIREMENTS
9.1. It is prohibited to operate safety devices in the absence of the documentation specified in paragraphs. 8.4, 8.5.
9.2. It is prohibited to operate valves at pressures and temperatures higher than those specified in the technical documentation for the valves.
9.3. It is prohibited to operate and test safety valves in the absence of outlet pipes that protect personnel from burns when the valves operate.
9.4. Pulse valves and direct-acting valves must be located in such a way that during adjustment and testing there is no possibility of burns to operating personnel.
9.5. It is not allowed to repair valve defects if there is pressure in the objects to which they are connected.
9.6. When repairing valves, it is prohibited to use wrenches whose jaw size does not correspond to the size of the fasteners.
9.7. All types of repair and maintenance work must be carried out in strict compliance with fire safety regulations.
9.8. When the power plant is located in a residential area, the exhausts of the gas-processing complex IPU must be equipped with noise-attenuating devices that reduce the noise level when the IPU is activated to sanitary permissible standards.
Annex 1
REQUIREMENTS FOR BOILER SAFETY VALVES
1. The valves must open automatically at the specified pressure without fail.
2. In the open position, the valves should operate steadily, without vibration or pulsation.
3. Requirements for direct acting valves:
3.1. The design of a lever-load or spring safety valve must include a device for checking the proper operation of the valve during boiler operation by forcing the valve to open.
The possibility of forced opening must be ensured at 80% of the opening pressure.
3.2. The difference between the response pressure (full opening) and the beginning of the valve opening should not exceed 5% of the response pressure.
3.3. Safety valve springs must be protected from direct heat and direct exposure to the working environment.
When the valve is fully opened, the possibility of contact between the coils of the spring must be excluded.
3.4. The design of the safety valve should not allow arbitrary changes in its adjustment during operation. The RGPC must have a device on the lever that prevents the movement of the load. For PPK, the screw that regulates the spring tension must be closed with a cap, and the screws securing the cap must be sealed.
4. Requirements for IPU:
4.1. The design of the main safety valves must have a device that softens the shock when they open and close.
4.2. The design of the safety device must ensure that the functions of protection against overpressure are maintained in the event of failure of any control or regulatory body of the boiler.
4.3. The design of the safety device must allow it to be controlled manually or remotely.
4.4. The design of the device must ensure its automatic closing at a pressure of at least 95% of the operating pressure in the boiler,
Appendix 2
METHOD FOR CALCULATING THE CAPACITY OF BOILER SAFETY VALVES
1. The total capacity of all safety devices installed on the boiler must meet the following requirements:
for steam boilers
G 1 + G 2 + ... + G n³ D k ;
for hot water boilers
G 1 + G 2 + ... + G n³ Q/g;
Calculation of the throughput capacity of safety valves of hot water boilers can be carried out taking into account the ratio of steam and water in the steam-water mixture passing through the safety valve when it is activated.
2. The capacity of the safety valve is determined by the formula;
G = 10 IN 1 a F (P 1 + 0.1) - for pressure in MPa;
G = IN a F(P 1 + 1) - for pressure in kgf/cm 2,
The values of this coefficient are selected from the table. 1 and 2 or determined by formulas.
At pressure P 1 in kgf/cm 2:
Under pressure R 1 to MPa:
Table 1
Coefficient values IN for saturated steam
table 2
Coefficient values IN for superheated steam
| Steam pressure R 1 , | Coefficient IN at steam temperature t n, °С | ||||||||
| MPa (kgf/cm 2) | 250 | 300 | 350 | 400 | 450 | 500 | 550 | 600 | 650 |
| 2,0 (20) | 0,495 | 0,465 | 0,445 | 0,425 | 0,410 | 0,390 | 0,380 | 0,365 | 0,355 |
| 3,0 (30) | 0,505 | 0,475 | 0,450 | 0,425 | 0,410 | 0,395 | 0,380 | 0,365 | 0,355 |
| 4,0 (40) | 0,520 | 0,485 | 0,455 | 0,430 | 0,410 | 0,400 | 0,380 | 0,365 | 0,355 |
| 6,0 (60) | 0,500 | 0,460 | 0,435 | 0,415 | 0,400 | 0,385 | 0,370 | 0,360 | |
| 8,0 (80) | 0,570 | 0,475 | 0,445 | 0,420 | 0,400 | 0,385 | 0,370 | 0,360 | |
| 16,0 (160) | 0,490 | 0,450 | 0,425 | 0,405 | 0,390 | 0,375 | 0,360 | ||
| 18,0 (180) | 0,480 | 0,440 | 0,415 | 0,400 | 0,380 | 0,365 | |||
| 20,0 (200) | 0,525 | 0,460 | 0,430 | 0,405 | 0,385 | 0,370 | |||
| 25,0 (250) | 0,475 | 0,445 | 0,415 | 0,390 | 0,375 | ||||
| 30,0 (300) | 0,495 | 0,460 | 0,425 | 0,400 | 0,380 | ||||
To calculate the capacity of safety valves of power plants with fresh steam parameters:
13.7 MPa and 560°C IN = 0,4;
25.0 MPa and 550°C IN = 0,423.
The formula for determining valve capacity should only be used if:
- for pressure in MPa;
For pressure in kgf/cm 2,
Where R 2 - maximum excess pressure behind the boiler in the space into which steam flows from the boiler (when it flows into the atmosphere R 2 = 0),
b - critical pressure ratio.
For saturated steam b cr = 0.577.
For superheated steam b cr = 0.546.
Appendix 3
FORMS OF TECHNICAL DOCUMENTATION ON BOILER SAFETY DEVICES, WHICH SHOULD BE MAINTAINED AT TPP
Form No. 1
I affirm:
Chief Engineer
______________________
"__" __________ 199__
Statement
response pressure of boiler safety devices
in ____________ workshop
Foreman ________________
Form No. 2
I affirm:
Chief Engineer
______________________
"__" __________ 199__
Decanter for checking boiler safety devices
| № | Number | Installed | Approximate timing for checking valves | ||||||||||||||||||||||||
| p.p. | boiler | periodicity | 199 | 199 | |||||||||||||||||||||||
| checks | Months | Months | |||||||||||||||||||||||||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | ||||
Foreman _______________
Note Depending on the length of time the boiler is under repair or in reserve, the timing of valve checks may be specified.
Form No. 3
Data
on forced testing of boiler safety valves
Form No. 4
Data
on scheduled and emergency repairs of boiler safety valves
Boiler No. _______
Appendix 4
BASIC TERMS AND DEFINITIONS
Based on the operating conditions of TPP boilers, taking into account the terms and definitions contained in various materials Gosgortekhnadzor of Russia, GOST and technical literature, the following terms and definitions are adopted in this Instruction.
1. Working pressure R p - maximum internal excess pressure that occurs during the normal course of the work process without taking into account hydrostatic pressure and without taking into account the permissible short-term increase in pressure during the operation of safety devices.
2. Design pressure R calculation - excess pressure for which the strength of the boiler elements was calculated. For TPP boilers, the design pressure is usually equal to the operating pressure.
3. Allowable pressure R extra - the maximum excess pressure allowed by accepted standards in the protected element of the boiler when the medium is discharged from it through a safety device
R additional = 1.1 P p.
Safety devices must be selected and adjusted in such a way that the pressure in the boiler (drum) cannot rise above R add.
4. Opening pressure R n.o - excess pressure at the valve inlet, at which the force aimed at opening the valve is balanced by the force holding the shut-off element on the seat.
Depending on the valve design and process dynamics P n.o = l.03¸l.08 P R. But due to the rapidity of the actuation process, there are a lot of lifting safety valves and IPU when adjusting them to determine P n.o. practically impossible.
5. Full opening pressure (set pressure) R cp is the maximum excess pressure that is established in front of the PC when it is fully opened. It should not exceed R add.
6. Closing pressure R h - excess pressure at which, after actuation, the shut-off element is seated on the seat,
For direct acting safety valves R z = 0.8¸0.9 R R. For IPU with electromagnetic drive R h must be at least 0.95 R R.
7. Bandwidth G- maximum mass flow rate of steam that can be completely discharged open valve at response parameters.
Appendix 5
DESIGNS AND TECHNICAL CHARACTERISTICS OF BOILER SAFETY VALVES
1. Live steam impulse safety devices
1.1. Main safety valves
To protect boilers from increased pressure on fresh steam pipelines, GPC series 392-175/95-0 g, 392-175/95-0 g -01, 875-125-0 and 1029-200/250-0 are used. On old power plants with parameters of 9.8 MPa, 540°C, valves of the 530 series are installed, and on blocks of 500 and 800 MW - series E-2929, which are currently out of production. At the same time, for newly designed boilers with parameters of 9.8 MPa, 540°C and 13.7 MPa, 560°C, the plant has developed new design valve 1203-150/200-0, and to replace the exhausted valves of the 530 series, which had two-way steam removal, valve 1202-150/150-0 is produced.
Specifications produced ChZEM GPK are given in table. 3.
Valves of the 392 and 875 series (Fig. 2) consist of the following main components and parts: connecting inlet pipe 1, connected to the pipeline by welding; housing 2 with a chamber in which the servo drive 6 is located; plates 4 and saddles 3, making up the shutter assembly; lower 5 and upper 7 rods; hydraulic damper unit 8, in the housing of which a piston and spring are located.
The steam supply in the valve is carried out to the spool. Pressing it against the seat with pressure from the working medium increases the tightness of the valve. Pressing the plate to the seat in the absence of pressure under it is ensured by a spiral spring placed in the damper chamber.
The valve of the 1029-200/250-0 series (Fig. 3) is fundamentally designed like the valves of the 392 and 875 series. The only difference is the presence of a throttle grille in the body and the removal of steam through two oppositely directed outlet pipes.
Table 3
Technical characteristics of the main safety valves IPU boilers
|
Valve designation |
Nominal diameter, mm | Steam operating parameters | Smallest area | Flow coefficient | Steam consumption at working | The course of the class | Weight, kg | ||||
| entrance- | exit- | Pressure | Tempe- temperature, °С |
for other | on the raft | passage- nogo section, mm 2 |
parameters, t/h | mm | |||
| Fresh steam valves | |||||||||||
| 1202-150/150-0 | 150 | 150 | 9,8 | 540 | 30,0 | 17,5 | 5470 | 0,5 | 120 | 20 | 415 |
| 1203-150/200-0-01 | 150 | 200 | 9,8 | 540 | 59,0 | 17,5 | 5470 | 0,5 | 120 | 20 | 345 |
| 1203-150/200-0 | 150 | 200 | 13,7 | 560 | 59,0 | 17,5 | 5470 | 0,5 | 165 | 20 | 345 |
| 392-175/95-0 g -01 | 175 | 200 | 9,8 | 540 | 30,0 | 17,5 | 4236 | 0,7 | 120 | 22 | 446 |
| 392-175/95-0 u | 175 | 200 | 13,7 | 560 | 30,0 | 20,0 | 4236 | 0,7 | 160 | 22 | 446 |
| 875-125-0 | 125 | 250 | 25,0 | 545 | 80,0 | 32,0 | 2900 | 0,7 | 240 | 22 | 640 |
| 1029-200/250-0 | 150 | 200 | 25,0 | 545 | 80,0 | 32,0 | 11300 | 0,7 | 850 | 28 | 2252 |
| E-2929 | 150 | 200 | 25,5 | 560 | 80,0 | 32,0 | 9400 | 0,7 | 700 | 28 | 2252 |
| Reheat steam valves | |||||||||||
| 111-250/400-0 b | 250 | 400 | 0,8-1,2 | 545 | 9,6 | 4,5 | 18700 | 0,7 | 50-80 | 40 | 727 |
| 111-250/400-0 b -0l | 250 | 400 | 1,3-3,7 | 545 | 9,6 | 4,5 | 18700 | 0,7 | 87-200 | 45 | 727 |
| 694-250/400-0 | 250 | 400 | 4,1 | 545 | 15,0 | 5,0 | 18700 | 0,7 | 200 | 45 | 652 |
| B-7162LMZ | 200 | 400 | 1,3-3,7 | 545 | 9,6 | 4,5 | 18700 | 0,7 | 87-200 | 45 | 590 |
The valves work as follows:
when the IR steam is opened, it enters the chamber above the servo piston through the pulse tube, creating pressure on it equal to the pressure on the spool. But since the area of the piston, which is affected by steam pressure, exceeds the similar area of the spool, a shifting force arises, moving the spool down and thereby opening the discharge of steam from the object. When the pulse valve is closed, the access of steam to the servo chamber is stopped, and the steam present in it is discharged through the drain hole into the atmosphere. In this case, the pressure in the chamber above the piston drops and due to the action of the medium pressure on the spool and the force of the spiral spring, the valve closes.
To prevent shocks when opening and closing the valve, its design includes a hydraulic damper in the form of a chamber located in the yoke coaxially with the servo drive chamber. The damper chamber contains a piston, which is connected to the spool using rods; According to the factory instructions, water or some other liquid of similar viscosity is poured or supplied into the chamber. When the valve opens, liquid flowing through small holes in the damper piston slows down the movement of the valve running gear and thereby softens the shock. When the valve running gear moves towards closing, a similar process occurs in the opposite direction 1. The valve seat is removable and is located between the connecting pipe and the body. The seat is sealed with comb metal gaskets. There is a hole in the side of the seat connected to the drainage system, into which the condensate that accumulates in the valve body after its operation is drained. To avoid spool vibration and rod breakage, guide ribs are welded into the connecting pipe.
The peculiarity of the valves of the 1202 and 1203 series (Fig. 4 and 5) is that in them the connecting pipe is made integral with the body and there is no hydraulic damper, the role of which is played by the throttle 8 installed in the cover on the line connecting the above-piston chamber with the atmosphere.
Just like the valves discussed above, valves of the 1203 and 1202 series operate on the principle of “loading”: when the IR is opened, the working medium is supplied to the above-piston chamber and when a pressure in it reaches 0.9 R p, begins to move the piston down, opening the release of the medium into the atmosphere.
The main parts of fresh steam valves are made of the following materials: body parts - steel 20KhMFL or 15KhMFL (t > 540°C), rods - steel 25Kh2M1F, spiral spring - steel 50KhFA.
The sealing surfaces of the valve parts are deposited with TsN-6 electrodes. Pressed rings made of asbestos-graphite cord grades AG and AGI are used as stuffing box packing. At a number of thermal power plants, a combined packing is used to seal the piston, including rings made of thermally expanded graphite, metal foil and foil made of thermally expanded graphite. The packing was developed by UNICHIMTEK and was successfully tested at ChZEM stands.
1 As the operating experience of a number of thermal power plants has shown, the valves operate without shock even in the absence of liquid in the damper chamber due to the presence of an air cushion under and above the piston.
Rice. 2. 392 and 875 series main relief valves:
1 - connecting pipe; 2 - body; 3 - saddle; 4 - plate; 5 - lower rod; 6 - servo drive unit; 7 - upper rod; 8 - hydraulic damper chamber; 9 - housing cover;
10 - damper piston; 11 - damper chamber cover
Rice. 3. 1029 series main safety valve
Rice. 4. 1202 series main relief valve:
1 - body; 2 - saddle; 3 - plate; 4 - servo drive unit; 5 - lower rod; 6 - upper rod;
7 - spring; 8 - throttle
1.2. Pulse valves
All fresh steam IPUs produced by ChZEM are equipped with pulse valves of the 586 series. The technical characteristics of the valves are given in table. 4, and the design solution in Fig. 6. Valve body - angular, flange connection between the body and the cover. A filter is mounted at the inlet of the valve, designed to capture foreign particles contained in the steam. The valve is driven by an electromagnetic drive, which is mounted on the same frame as the valve. To ensure that the valve operates when the voltage in the electromagnet power supply system disappears, a weight is suspended on the valve lever, by moving which you can adjust the valve to operate at the required pressure.
Table 4
Technical characteristics of pulse valves for fresh steam and reheat steam
| Valve designation | Conditional passage | Work Environment Settings | Test pressure during testing, MPa | |||
| (drawing number) | D y, mm | Pressure, MPa | Temperature, °C | for strength | on density | Weight, kg |
| 586-20-EM-01 | 20 | 25,0 | 545 | 80,0 | 32,2 | 226 |
| 586-20-EM-02 | 20 | 13,7 | 560 | 80,0 | 17,5 | 206 |
| 586-20-EM-03 | 20 | 9,8 | 540 | 80,0 | 12,5 | 191 |
| 586-20-EMF-03 | 20 | 4,0 | 285 | 15,0 | 5,0 | 198 |
| 586-20-EMF-04 | 20 | 4,0 | 545 | 15,0 | 5,0 | 193 |
| 112-25x1-OM | 25 | 4,0 | 545 | 9,6 | 4,3 | 45 |
| 112-25x1-0 | 25 | 1,2 | 425 | 9,6 | 1,4 | 31 |
| 112-25х1-0-01 | 25 | 3,0 | 425 | 9.6 | 3,2 | 40 |
| 112-25х1-0-02 | 25 | 4,3 | 425 | 9,6 | 4,3 | 45 |
Rice. 5. 1203 series main safety valve
Rice. 6. Fresh steam pulse valve:
A- valve design; b - installation diagram of the valve on the frame together with electromagnets
To ensure minimal inertia of the IPU operation, pulse valves should be installed as close as possible to the main valve.
2. Pulse-safety devices for reheating steam
2.1. Main safety valves
GPK ChZEM and LMZ are installed on the cold reheating pipelines of boilers D at 250/400 mm. Technical characteristics of the valves are given in table. 3, the design solution of the reheat valve ChZEM is shown in Fig. 7. Main components and parts of the valve: body of pass-through type 1, connected to the pipeline by welding; a shutter assembly consisting of a seat 2 and a plate 3, connected via a thread to the rod 4; glass 5 with a servo drive, the main element of which is a piston 6 sealed with an stuffing box; spring load unit, consisting of two successively arranged spiral springs 7, the required compression of which is carried out by screw 8; throttle valve 9, designed to dampen the shock when closing the valve by regulating the rate of steam removal from the above-piston chamber. The seat is installed between the body and the glass on grooved gaskets and is crimped when tightening the cover fasteners. Centering of the spool in the seat is ensured by guide ribs welded to the spool.
Rice. 7. Main reheat steam safety valves of series 111 and 694:
1 - body; 2 - saddle; 3 - plate; 4 - rod; 5 - glass; 6 - servo piston; 7 - spring; 8 - adjusting screw; 9 - throttle valve; A - steam input from the pulse valve;
B - release of steam into the atmosphere
The main parts of the valves are made of the following materials: body and cover - steel 20GSL, upper and lower rods - steel 38ХМУА, spring - steel 50ХФА, stuffing box - cord AG or AGI. The sealing surfaces of the factory-made valve parts are welded with TsT-1 electrodes. The operating principle of the valve is the same as that of fresh steam valves. The main difference is the way the shock is damped when the valve closes. In the HPC reheat steam, the degree of shock damping is adjusted by changing the position of the throttle needle and tightening the spiral spring.
The main safety valves, intended for installation on the hot reheat line, series 694 differ from the cold reheat valves of the 111 series described above in the material of the body parts. The body and cover of these valves are made of 20ХМФЛ steel.
The GPKs supplied for installation on the cold reheat line, manufactured by LMZ (Fig. 8), are similar to the ChZEM series 111 valves, although they have three fundamental differences:
The servo piston is sealed using cast iron piston rings;
the valves are equipped with a limit switch, which allows information about the position of the shut-off element to be transmitted to the control panel;
There is no throttling device on the steam discharge line from the above-piston chamber, which eliminates the possibility of adjusting the degree of shock damping or valve closing and, in many cases, contributes to the occurrence of a pulsating mode of operation of the valves.
Rice. 8. Main safety valve for reheating steam, LMZ design
2.2. Pulse valves
Lever-load valves are used as pulse valves of the IPU ChZEM reheating system D for 25 mm series 112 (Fig. 9, Table 4). The main parts of the valve: body 1, seat 2, spool 3, rod 4, sleeve 5, lever 6, weight 7. The seat is removable, installed in the body and, together with the body, in the connecting pipe. The spool is located in the inner cylindrical bore of the seat, the wall of which plays the role of a guide. The rod transmits force to the spool through the ball, which prevents the valve from skewing when the valve closes. The valve is set to operate by moving a weight on the lever and then locking it in a given position.
Rice. 9. Pulse valve IPU ChZEM for reheat steam, series 112:
1 - body; 2 - saddle; 3 - spool; 4 - rod; 5 - bushing; 6 - lever; 7 - load
The parts are made from the following materials; body - steel 20, rod - steel 25Х1МФ, spool and seat - steel 30Х13.
For valves intended for IPU hot reheating, the body 112-25x1-OM is made of 12ХМФ steel. ChZEM pulse valves for the reheating system are supplied without an electromagnetic drive, LMZ valves are supplied with an electromagnetic drive.
3. Direct acting valves PA "Krasny Kotelshchik"
Spring safety valves T-31M-1, T-31M-2, T-31M-3, T-32M-1, T-32M-2, T-32M-3, T-131M, T-132M produced by the Krasny production association boilermaker" (Fig. 10).
Spring valves, full lift. They have a cast corner housing and are installed only in vertical position in places with an ambient temperature not higher than +60°C. When the pressure of the medium under the valve increases, plate 2 is pressed away from the seat, and a stream of steam flows out from high speed through the gap between the plate and the guide sleeve 4, has a dynamic effect on the lifting sleeve 5 and causes a sharp rise of the plate to a given height. By changing the position of the lifting sleeve relative to the guide sleeve, it is possible to find its optimal position, which ensures both sufficiently rapid opening of the valve and its closing with a minimal decrease in pressure relative to the operating pressure in the protected system. To ensure that when the valve opens, a minimum release of steam into the surrounding space is made in the valve cover, a labyrinth seal is made, consisting of alternating aluminum and paronite rings. Setting the valve to operate at a given pressure is carried out by changing the degree of tightening of spring 6 using a pressure threaded bushing 7. The pressure bushing is closed by a cap 8, secured with two screws. A control wire is passed through the screw heads, the ends of which are sealed.
To check the operation of the valves during operation of the equipment, a lever 9 is provided on the valve.
Technical characteristics of the valves, overall and connecting dimensions are given in table. 5.
The valve is currently available with a welded body. Technical characteristics of valves and springs installed on them are given in table. 6 and 7.
Rice. 10. Spring safety valve "Krasny Kotelshchik":
6 - spring, 7 - pressure threaded bushing; 8 - cap; 9 - lever
Table 5
Technical characteristics of spring safety valves, old releases produced by PA "Krasny Kotelshchik"
| Cipher | Diameter | Working | Maximum | Coefficient | Least | Spring data | Pressure | Weight | |||
| valve | nominal diameter, mm | pressure, MPa (kgf/cm2) | working environment temperature, °C | consumption, d | flow path area F, mm 2 | Serial number of spring detail drawing | Wire diameter, mm | Outer diameter of spring, mm | Spring height in free state, mm | leak testing, MPa (kgf/cm2) | valve, kg |
| T-31M-1 | 50 | 3,4-4,5 | K-211946 | 18 | 110 | 278 | 4,5 (45) | 48,9 | |||
| Version 1 | |||||||||||
| T-31M-2 | 50 | 1,8-2,8 | 450 | 0,65 | 1960 | Version 2 | 16 | 106 | 276 | 2,8 (28) | 47,6 |
| T-31M-3 | 50 | 0,7-1,5 | Version 3 | 12 | 100 | 285 | 1,5 (15) | 45,5 | |||
| T-31M | 50 | 5,0-5,5 | K-211948 | 18 | 108 | 279 | 5,5 (55) | 48,3 | |||
| T-32M-1 | 80 | 3,5-4,5 | K-211817 | 22 | 140 | 304 | 4,5 (45) | 77,4 | |||
| Version 1 | |||||||||||
| T-32M-2 | 80 | 1,8-2,8 | 450 | 0,65 | 3320 | Version 2 | 18 | 128 | 330 | 2,8 (28) | 74,2 |
| T-32M-3 | 80 | 0,7-1,5 | Version 3 | 16 | 128 | 315 | 1,5 (15) | 73,4 | |||
| T-131M | 50 | 3,5-4,0 | 450 | 0,65 | 1960 | K-211947 Version 1 |
18 | 110 | 278 | 4,5 (45) | 49,7 |
| T-132M | 80 | 3,5-4,0 | 450 | 0,65 | 3320 | K-211817 Version 1 |
22 | 140 | 304 | 4,5 (45) | 80,4 |
Table 6
Technical characteristics of spring safety valves produced by Krasny Kotelshchik Production Association
|
Valve code |
Inlet flange |
Outlet flange |
Limit parameters of operating conditions | Design diameter, mm / design | Opening start pressure, MPa**/kgf/cm2 | Designation | Spring designation | Spring tension height | Valve weight, kg | Flow coefficient | ||||
| Nominal diameter, mm | Conditional pressure, MPa/kgf/cm2 | Nominal diameter, mm | Conditional pressure, MPa/kgf/cm2 | Working pressure, MPa/kgf/cm2 | Ambient temperature, °C | flow area, mm 2 | h 1 , mm | a | ||||||
| T-31M-1 | 50 | 6,4/64 | 100 | 1,6/16 | Steam | 3,5-4,5/35-45 | 425-350* | 48/1810 | 4.9±0.1/49±1 | 08.9623.037 | 08.7641.052-04 | 200 | 47,8 | 0,65 |
| T-31M-2 | 50 | 6,4/64 | 100 | 1,6/16 | -"- | 1,8-2,8/18-28 | Up to 425 | 48/1810 | 3.3±0.1/33±1 | 08.9623.037-03 | 08.7641.052-02 | 200 | 46,5 | 0,65 |
| T-31M-3 | 50 | 6,4/64 | 100 | 1,6/16 | -"- | 0,7-1,5/7-15 | Up to 425 | 48/1810 | 1.8±0.1/18±1 | 08.9623.037-06 | 08.7641.52 | 170 | 44,5 | 0,65 |
| T-32M-1 | 80 | 6,4/64 | 150 | 1,6/16 | -"- | 3,5-4,5/35-45 | 425-350* | 62/3020 | 4.95±0.1/49.5±1 | 08.9623.039 | 08.7641.052-06 | 210 | 75,8 | 0,65 |
| T-32M-2 | 80 | 6,4/64 | 150 | 1,6/16 | -"- | 1,8-2,8/18-28 | 425 | 62/3020 | 3.3±0.1/33±1 | 08.9623.039-03 | 08.7641.052-04 | 220 | 72,11 | 0,65 |
| T-131M | 50 | 10/100 | 100 | 1,6/16 | -"- | 3,5-4,5/35-45 | 450 | 48/1810 | 4.95±0.1/49.5±1 | 08.9623.048 | 08.7641.052-04 | 200 | 48,8 | 0,65 |
| T-132M | 80 | 10/100 | 150 | 1,6/16 | -"- | 3,5-4,5/35-45 | 450 | 62/3020 | 4.9±0.1/49±1 | 08.9623.040 | 08.7641.052-06 | 210 | 76,1 | 0,65 |
| *More low temperature is the limit for higher pressure. | ||||||||||||||
| ** Limit of factory tests of valves for detonation. | ||||||||||||||
Table 7
Technical characteristics of springs installed on valves of the Krasny Kotelshchik Production Association
| Geometric dimensions | Spring force at | Working | Expanded | Weight, kg | ||||||
| Designation | Outer | Diameter | Spring height in | Step | Number of turns | working deformation | deformation | spring length, | ||
| springs | diameter, mm | rod, mm | free state, mm | windings, mm | working n | complete n 1 | F, kgf(N) | springs S 1, mm | mm | |
| 06.7641.052 | 27,9 | 8±0.5 | 12 | 340 (3315,4) | 3000 | 2,55 | ||||
| 08.7641.052-01 | 32,7 | 8±0.3 | 10 | 540(5296,4) | 3072 | 4,8 | ||||
| 08.7641.052-02 | 31,5 | 8±0.3 | 10 | 620(6082,2) | 2930 | 4,7 | ||||
| 08.7641.052-03 | 29,0 | 8±0.3 | 10 | 370(3623,7) | 3072 | 4,7 | ||||
| 08.7641.052-04 | 31,5 | 8±0.3 | 10 | 1000(9810) | 3000 | 6,0 | ||||
| 08.7641.052-05 | 36,5 | 7±0.3 | 9 | 1220(11968,2) | 2660 | 5,4 | ||||
| 08.7641.052-06 | 41,7 | 6.5±0.3 | 8,5 | 1560(15308,1) | 3250 | 9,8 | ||||
| 08.7641.052-07 | 41,7 | 6.5±0.3 | 8,5 | 1700(16677) | 3300 | 9,5 | ||||
List of used literature
1. Rules for the design and safe operation of steam and hot water boilers, - M.: NPO OBT, 1993.
2. GOST 24570-81 (ST SEV 1711-79). Safety valves for steam and hot water boilers. Technical requirements.
3. Instructions for organizing the operation, procedure and timing of checking impulse safety devices of boilers with steam pressure above 4.0 MPa: RD 34.26.301-91.- M.: SPO ORGRES, 1993.
4. Instructions for organizing the operation, procedure and timing of testing impulse safety devices of boilers with operating steam pressure from 1.4 to 4.0 MPa (inclusive): RD 34.26.304-91.- M.: SPO ORGRES. 1993.
5. Pulse safety devices of the Chekhov plant "Energomash". Technical description and operating instructions.
6. Safety valves of JSC "Krasny Kotelshchik". Technical description and operating instructions.
7. GOST 12.2.085-82 (ST SEV 3085-81). Pressure vessels. Safety valves. Safety requirements.
8. Gurevich D.F., Shpakov O.N. Designer's reference pipeline fittings.- L.: Mechanical Engineering, 1987.
9. Power fittings for thermal power plants and nuclear power plants. Industry directory directory. - M.: TsNIITEITyazhmash, 1991.
1. General Provisions
2. Basic requirements for protecting boilers from pressure increases above the permissible value
3. Instructions for installing safety devices
4. Preparing valves for operation
5. Adjustment of safety devices to operate at a given pressure
6. Procedure and timing for checking valves
8. Organization of operation
9. Safety requirements
Appendix 1. Requirements for boiler safety valves
Appendix 2. Methodology for calculating the capacity of boiler safety valves
Appendix 3. Forms of technical documentation on safety devices of boilers, which must be maintained at thermal power plants
Appendix 4. Basic terms and definitions
Appendix 5. Designs and technical characteristics of boiler safety valves
List of used literature
e) not to start work or stop work under conditions that do not ensure safe operation of equipment under pressure, and in cases of deviations from technological process and unacceptable increase (decrease) in the values of operating parameters of equipment under pressure;
E) act in accordance with the requirements established by the instructions in cases of accidents and incidents during the operation of pressure equipment.
222. Quantity responsible persons specified in subparagraph "b" of paragraph 218 of these FNP, and (or) the number of production control service and its structure must be determined by the operating organization taking into account the type of equipment, its quantity, operating conditions and requirements of operational documentation, based on the calculation of the time required for timely and high-quality fulfillment of duties assigned to responsible persons by job descriptions and administrative documents of the operating organization.
The operating organization must create conditions for responsible specialists to perform their duties.
223. Responsibility for the good condition and safe operation of pressure equipment should be assigned to specialists with technical professional education, to whom the specialists and workers who provide maintenance and repair of this equipment are directly subordinate, for which, taking into account the structure of the operating organization, specialists responsible for the good condition of the pressure equipment and specialists responsible for its safe operation can be appointed.
During vacation, business trip, illness or in other cases of absence of responsible specialists, the performance of their duties is assigned by order to the workers replacing them by position, having the appropriate qualifications, and having passed industrial safety certification in the prescribed manner.
224. Certification of specialists responsible for the good condition and safe operation of pressure equipment, as well as other specialists whose activities are related to the operation of pressure equipment, is carried out by the certification commission of the operating organization in accordance with the certification regulations, with participation in the work of this commission A representative of the territorial body of Rostechnadzor is not required. Periodic certification of responsible specialists is carried out once every five years.
The certification commission of the operating organization must include a specialist responsible for carrying out production control over the safe operation of pressure equipment, certified in accordance with the certification regulations.
225. The specialist responsible for carrying out production control over the safe operation of pressure equipment must:
A) inspect equipment under pressure and check compliance with established operating conditions;
B) exercise control over the preparation and timely presentation of pressure equipment for inspection and keep records of pressure equipment and records of its surveys in paper or electronic form;
C) exercise control over compliance with the requirements of these FNP and legislation Russian Federation in the field of industrial safety during the operation of equipment under pressure, when violations of industrial safety requirements are identified, issue binding instructions to eliminate violations and monitor their implementation, as well as the implementation of instructions issued by a representative of Rostechnadzor and other authorized bodies;
D) monitor the timeliness and completeness of repairs (reconstruction), as well as compliance with the requirements of these FNP when carrying out repair work;
D) check compliance established order admission of workers, as well as issuing production instructions to them;
E) check the correctness of technical documentation during operation and repair of pressure equipment;
G) participate in inspections and inspections of pressure equipment;
H) demand removal from work and an extraordinary knowledge test for workers who violate industrial safety requirements;
I) control the conduct of emergency drills;
J) fulfill other requirements of documents defining his job responsibilities.
226. The specialist responsible for the good condition and safe operation of pressure equipment must:
A) ensure the maintenance of pressure equipment in good (workable) condition, compliance by maintenance personnel with production instructions, timely repairs and preparation of equipment for technical examination and diagnostics, as well as control over the safety, completeness and quality of their implementation;
B) inspect equipment under pressure at a frequency determined by the job description and ensure compliance with safe operating conditions;
(Subclause as amended, put into effect on June 26, 2018 by order of Rostechnadzor dated December 12, 2017 N 539. - See previous edition)
C) check the entries in the shift log with signatures in it;
D) store passports of pressure equipment and manuals (instructions) of manufacturing organizations for installation and operation, unless a different procedure for storing documentation is established by the administrative documents of the operating organization;
E) participate in inspections and technical examinations of pressure equipment;
E) conduct emergency training with maintenance personnel;
G) promptly comply with instructions to eliminate identified violations;
H) keep records of the operating time of loading cycles of equipment under pressure operated in cyclic mode;
I) fulfill other requirements of documents defining his job responsibilities.
227. Vocational training and issuance of documents on education and (or) qualifications of workers (workers and other categories of personnel (hereinafter referred to as personnel (workers)) allowed to service equipment under pressure must be carried out in organizations that carry out educational activities, in accordance with the requirements of the legislation of the Russian Federation in the field of education. The need for advanced training in educational organization or conducting additional practical training (training) on safe work methods in production should be determined by the operating organization depending on the results of knowledge testing, analysis of the causes of incidents, accidents and injuries, as well as in cases of reconstruction, technical re-equipment hazardous production facilities with the introduction of new technologies and equipment that require more high level qualifications. The procedure for conducting practical training in safe work methods, internships, testing knowledge on safe work methods and admission to independent work must be determined by the administrative documents of the operating organization.
228. Periodic testing of the knowledge of personnel (workers) servicing pressure equipment should be carried out once every 12 months. An extraordinary knowledge test is carried out by:
A) when moving to another organization;
B) when replacing, reconstructing (modernizing) equipment, as well as making changes to the technological process and instructions;
C) in the case of transfer of workers to service boilers of a different type, as well as in the transfer of the boiler they service to combustion of a different type of fuel.
A commission to test the knowledge of equipment servicing personnel (workers) must be appointed by order of the operating organization; the participation of a representative of Rostechnadzor in its work is not required.
(Paragraph as amended, put into effect on June 26, 2018 by order of Rostechnadzor dated December 12, 2017 N 539. - See previous edition)
The results of testing the knowledge of service personnel (workers) are documented in a protocol signed by the chairman and members of the commission with a note in the certificate of admission to independent work.
229. Before initial admission to independent work after vocational training, before admission to independent work after an extraordinary knowledge test provided for in paragraph 228 of these FNP, as well as during a break in work in their specialty for more than 12 months, service personnel (workers) must undergo a knowledge test after testing internship to acquire (restore) practical skills. The internship program is approved by the management of the operating organization. The duration of the internship is determined depending on the complexity of the technological process and the pressure equipment.
Personnel access to self-service equipment under pressure must be issued by order (instruction) for the workshop or organization.
Requirements for boiler operation
230. The boiler room must have a clock and a telephone for communication with steam consumers and hot water, as well as with technical services and administration of the operating organization. When operating waste heat boilers, in addition, a telephone connection must be established between the consoles of waste heat boilers and heat sources.
231. Persons who are not related to the operation of boilers and other associated main and auxiliary equipment should not be allowed into buildings and premises in which boilers are operated. IN necessary cases unauthorized persons may be allowed into these buildings and premises only with the permission of the operating organization and accompanied by its representative.
(Clause as amended, put into effect on June 26, 2018 by order of Rostechnadzor dated December 12, 2017 N 539. - See previous edition)
232. It is prohibited to entrust specialists and workers on duty servicing boilers to perform any other work not provided for during boiler operation. production instructions for the operation of the boiler and technological auxiliary equipment.
233. It is prohibited to leave the boiler without constant supervision by maintenance personnel, both during operation of the boiler and after it is stopped until the pressure in it decreases to a value equal to atmospheric pressure.
It is allowed to operate boilers without constant monitoring of their operation by maintenance personnel if there is automation, alarms and protections that provide:
A) maintaining the design operating mode;
B) prevention emergency situations;
(Subclause as amended, put into effect on June 26, 2018 by order of Rostechnadzor dated December 12, 2017 N 539. - See previous edition)
C) stopping the boiler in case of violations of the operating mode, which may cause damage to the boiler.
234. Areas of boiler elements and pipelines with elevated surface temperatures, with which direct contact of operating personnel is possible, must be covered with thermal insulation that ensures an outer surface temperature of no more than 55°C at an ambient temperature of no more than 25°C.
235. When operating boilers with cast iron economizers, it is necessary to ensure that the water temperature at the outlet of the cast iron economizer is at least 20°C lower than the saturated steam temperature in the steam boiler or the boiling temperature at the operating water pressure in the hot water boiler.
(Clause as amended, put into effect on June 26, 2018 by order of Rostechnadzor dated December 12, 2017 N 539. - See previous edition)
236. When burning fuel in boilers, the following must be provided:
A) uniform filling of the firebox with a torch without throwing it onto the walls;
B) eliminating the formation of stagnant and poorly ventilated zones in the volume of the furnace;
IN) stable combustion fuel without flame separation or breakthrough in a given range of operating modes;
D) preventing drops of liquid fuel from falling onto the floor and walls of the furnace, as well as separation of coal dust (unless special measures are provided for its afterburning in the volume of the furnace). When burning liquid fuel, it is necessary to install trays with sand under the nozzles to prevent fuel from getting onto the boiler room floor.
RUSSIAN JOINT STOCK COMPANY OF ENERGY AND ELECTRIFICATION "UES OF RUSSIA"INSTRUCTIONS
ON THE OPERATION, PROCEDURE AND TIMELINES FOR CHECKING SAFETY DEVICES OF VESSELS, APPARATUS AND PIPELINES OF TPP
RD 153-34.1-39.502-98
UDC 621.183 + 621.646
Enters into force on December 1, 2000.
Developed by the Open Joint Stock Company "Company for setting up, improving technology and operating power plants and networks of ORGRES"
Performer V.B. KAKUZIN
Agreed with Gosgortekhnadzor of Russia (Letter dated July 31, 1998 No. 12-22/760)
Deputy Head of Department N.A. HAPONEN
Approved by the Department of Development Strategy and Scientific and Technical Policy of RAO UES of Russia on July 27, 1998
First Deputy Chief A.P. BERSENEV
1. GENERAL PROVISIONS
1.1. This Instruction applies to safety devices (SD) installed on vessels, apparatus and pipelines of thermal power plants operating on steam and water.
1.2. The instructions do not apply to those control units of steam and hot water boilers that are subject to the requirements and.
1.3. The instructions contain the basic requirements for installing the control units and determine the procedure for their adjustment, operation and maintenance.
Appendices 1-4 of the Instructions set out the basic requirements for control systems of power plants, contained in the Rules and Gosgortekhnadzor of Russia and GOST 12.2.085-82 and GOST 24570-81, and provide the technical characteristics of valves used to protect the equipment of thermal power plants from pressure increases above the permissible values, methods for calculating the capacity of safety valves (SV) and a number of other materials of practical interest for operating personnel of power plants.
The instructions are aimed at improving the safety of operation of power plant equipment.
1.4. With the publication of this Instruction, the “Instructions for the operation, procedure and timing of inspection of safety devices of vessels, apparatus and pipelines of thermal power plants” (Moscow: SPO Soyuztekhenergo, 1981) becomes invalid.
1.5. The following abbreviations are adopted in the Instructions:
BROW- high-speed reduction-cooling unit;
Civil Procedure Code- main safety valve;
IR- pulse valve;
IPU- impulse safety device;
MPU- membrane safety device;
NTD- scientific and technical documentation;
PVD- high pressure heater;
PC- safety valve;
HDPE- low pressure heater;
PPK- direct acting spring safety valve;
PU- safety device;
PEN- electric feed pump;
RBNT- low point expansion tank;
RGPC- direct-acting lever-load valve;
RD- management documentation;
ROW- reduction-cooling unit;
TPN- turbo feed pump;
TPP- thermal power plant.
2. BASIC TERMS AND DEFINITIONS
Based on the operating conditions of vessels, apparatus and pipelines at thermal power plants, the operating principle of the control devices used to protect them, taking into account the terms and definitions contained in various GOSTs, regulatory documents Gosgortekhnadzor of Russia and technical literature, the following terms and definitions are adopted in this Instruction.
2.1. Operating pressureR slave – the maximum internal excess pressure that occurs during the normal course of the working process without taking into account the hydrostatic pressure of the medium and a short-term increase in pressure during the operation of the PU.
2.2. Design pressureR races - excess pressure for which the strength of elements of vessels, apparatus and pipelines was calculated.
The design pressure must be no less than the working pressure.
2.3. Allowable pressureR extra - the maximum excess pressure allowed by accepted standards that can arise in the protected object when the medium is discharged from it through the PU. Relationship between R extra And R slave (R races) is given in the table.
Safety devices must be selected and adjusted in such a way that the pressure in the vessel or apparatus cannot rise above the permissible pressure.
2.4. Opening pressureR But- excess pressure in the protected object, at which the shut-off element begins to move (the force tending to open the valve is balanced by the force holding the shut-off element on the seat)
The opening pressure must always be higher than the operating pressure.
2.5. Full opening pressureR open- the lowest excess pressure in front of the valve at which the required throughput is achieved.
2.6. Response pressureR Wed- maximum excess pressure that is established in front of the launcher when it is fully opened.
The response pressure should not exceed R extra .
Based on operating experience and tests, it has been established that for the IPU the response pressure is almost equal to the pressure at which the IR opens, while for the full-lift PPK the lifting time to the stroke value is 0.008-0.04 s. Hence, the value of the excess of the full actuation pressure over the opening pressure depends on the rate of pressure increase in the protected object. Taking into account possible fluctuations of the shut-off element, the use of full-lift valves is recommended in systems with a rate of pressure increase:
0.5 0 0.1 s
2.7. Closing pressure R zach - excess pressure in front of the valve, at which, after actuation, the shut-off element is seated on the seat.
2.8. BandwidthG - maximum mass flow of the working medium that can be discharged through a fully open valve at response parameters.
The methodology for calculating the throughput capacity of PC vessels, regulated by GOST 12.2.085-82, is given in Appendix 2. Calculation of the throughput capacity of PC pipelines is regulated by GOST 24570-81.
3. INSTALLATION OF SAFETY DEVICES
3.1. To protect vessels, apparatus and pipelines of thermal power plants from pressure increases above the permissible value, it is allowed to use:
direct acting safety valves: PPK and RGPK;
impulse safety devices;
safety devices with rupture membranes;
other devices, the use of which has been approved by the Gosgortekhnadzor of Russia.
3.2. Installation of PU on vessels, apparatus and pipelines, the design pressure of which is less than the pressure of the sources feeding them, is carried out in accordance with the normative and technical documentation and safety rules. The quantity, design, installation location of the PC and direction of discharge are determined by the project.
3.3. If the design pressure of the vessel is equal to the pressure of the source feeding them or exceeds it and the possibility of pressure increase in the vessel from chemical reaction or heating, then installing a control unit and a pressure gauge on it is optional.
3.4. When choosing the number and design of the PU, one should proceed from the need to exclude the possibility of increasing the pressure in the protected object above the permissible value. In this case, the choice of equipment protection method should include the following steps:
analysis of possible emergency situations (including erroneous actions of personnel) that can lead to an increase in pressure in the equipment or thermal circuit unit in question, and determination based on its calculated (most dangerous) emergency situation;
identification of the most weakened element of the protected object, which regulates the value of the design pressure that determines the triggering settings of the launcher;
determination of the mass and parameters of the process medium that must be discharged through the control unit;
based on the technological features of the protected system, construction of protection circuits and selection of the type and design of the control unit;
determination of PU response pressure values;
determination, taking into account the resistance of the pipelines, the required flow section of the PU and their number. It is allowed to use a combination of different types of launchers with a shift in their response settings.
3.5. Safety devices must be installed in places convenient for their installation, maintenance and repair.
3.6. Safety valves must be installed vertically on the highest part of the apparatus or vessel so that when they are opened, vapors and gases are removed from the protected object first. It is allowed to install the PC on pipelines or special branches in close proximity to the protected object.
3.7. It is prohibited to install shut-off devices between the control panel and the protected object and behind the control panel.
3.8. The fittings in front of (behind) the PU can be installed provided that two PU are installed and there is a lock (switching device) that excludes the possibility of simultaneous shutdown of both PU. When switching from one control center to another, the total throughput of the PCs in operation must ensure that the requirements of clause 3.4 of this Instruction are met.
3.9. The internal diameter of the supply pipeline must be no less than the internal diameter of the PC inlet pipe.
3.10. When installing several PCs on one branch pipe (pipeline), the internal diameter of the branch pipe (pipeline) must be calculated based on the required PC throughput. In this case, when determining the cross-section of connecting pipelines with a length of more than 1000 mm, it is necessary to take into account the value of their resistance.
3.11. Connecting and impulse pipelines of the PU must be protected from freezing of the working environment in them.
3.12. Sampling of the working medium from the pipes (and in sections of connecting pipelines from the protected object to the control unit) on which the control units are installed is not allowed.
3.13. The environment from the PC must be diverted to a safe place. In cases where the working medium is water, it must be discharged into an expander or other vessel designed to receive water from the PC.
3.14. The internal diameter of the outlet pipeline must be no less than the internal diameter of the PC outlet pipe. In the case of combining the outlet pipes of several valves, the cross-section of the collector must be no less than the sum of the cross-sections of the outlet pipes of these valves.
3.15. The installation of noise suppression devices on the discharge pipeline of the control room should not cause a reduction in the throughput of the control unit below the value required by safety conditions. When equipping the outlet pipeline with a noise-attenuating device, a fitting for installing a pressure gauge must be provided immediately behind the PC.
3.16. The total resistance of the outlet pipelines, including the noise-attenuating device, must be such that at a flow rate equal to the maximum throughput of the control unit, the back pressure in the outlet pipe of these control devices does not exceed 25% of the response pressure of the control device.
3.17. The discharge pipelines of the PU and the impulse lines of the PU in places where condensate may accumulate must have drainage devices to remove it.
Installation of shut-off devices or other fittings on drainage devices pipelines are not allowed.
3.18. The riser (vertical pipeline) through which the medium is discharged into the atmosphere must be securely fastened and protected from precipitation.
3.19. In PC pipelines, the necessary compensation for temperature expansions must be provided. The fastening of the housing and pipelines of the PC must be calculated taking into account static loads and dynamic forces that arise when the PC is activated.
3.20. Pipelines supplying the medium to the PC along their entire length must have a slope towards the vessel. It is necessary to exclude sudden changes in the walls of these pipelines when the PC is activated.
3.21. In cases where the protection of an object from increased pressure is carried out by IPU, the distance between the IR and GPC fittings must be at least 500 mm. The length of the connecting line between the IR and the GPC should not exceed 2.5 m.
3.22. When using an IPU with an IR equipped with an electromagnetic drive, the electromagnets must be powered from two independent power sources, ensuring that the IPU operates when the auxiliary voltage disappears. In those IPUs in which the GPC automatically opens when the power supply is turned off, one power source is allowed.
3.23. In thermal circuits of thermal power plants, the use of membrane PUs for protection against pressure increases is allowed only at those facilities, the shutdown of which does not lead to the shutdown of the main equipment (boilers, turbines). Examples of the possible use of MPU in thermal circuits of thermal power plants are discussed in Appendix 3.
3.24. To protect energy facilities, it is allowed to use MPUs designed and manufactured by enterprises that have permission from the Gosgortechnadzor authorities of Russia.
3.25. Clamping fixtures for installing membranes can be manufactured by the customer himself in strict accordance with drawings developed by a specialized organization. Each safety membrane must have a company mark indicating the response pressure and the permissible operating temperature during operation.
3.26. At least once every 2 years, it is necessary to carry out preventive replacement of membranes.
4. ADJUSTING SAFETY VALVES
4.1. Adjustment of the PC for operation is carried out:
after completing the installation of the vessel (apparatus, pipeline) before putting it into operation;
after repair, if the PC was replaced or overhauled (complete disassembly, grooving of sealing surfaces, replacement of chassis parts, etc.), and for PPK and in case of spring replacement.
4.2. Pulse safety devices and RGPC are regulated at the valve installation workplace; PPK can be adjusted both at the workplace and at a special stand with steam or air of appropriate pressure.
The basic design solution of the stand is shown in Fig. 1.
Rice. 1. PC test bench
4.3. Before starting work on adjusting the PC, the following organizational and technical measures must be completed:
4.3.1. Good lighting is provided for workplaces, passages, service areas and the PCs themselves.
4.3.2. A two-way connection has been established between the PC adjustment points and the control panel.
4.3.3. Shift and adjustment personnel involved in PC adjustment work were instructed. Personnel must know the design features of the PUs subject to adjustment and the requirements of the RD for their operation.
4.4. Immediately before starting adjustment and testing of the PU:
4.4.1. Check that all installation and adjustment work has been stopped in those systems in which the steam pressure necessary for adjusting the PC will be created, on the PUs themselves and their discharge pipelines.
4.4.2. Check the reliability of disconnecting those systems in which pressure will increase from adjacent systems. All shut-off valves in the closed position, as well as valves on open drainage lines, must be tied with a chain, and posters “Do not open, people are working” and “Do not close, people are working” must be posted on it.
4.4.3. All unauthorized people must be removed from the PC adjustment area.
4.5. To adjust PCs, a pressure gauge with an accuracy class of at least 1.0 must be installed in close proximity to them. Before installation, it must be tested in the laboratory using a standard pressure gauge.
4.6. Adjustment of the IPU with a lever-weight pulse valve should be done in the following order:
4.6.1. Move the IR weights to the edge of the lever.
4.6.2. Set the response pressure in the protected object in accordance with the requirements of the table.
4.6.3. Slowly move the weight on the lever towards the body to the position at which the GPC is triggered.
4.6.4. Raise the pressure in the vessel again to the value at which the GPC opens. If necessary, adjust the position of the weight on the lever and recheck the correct operation of the valve.
4.6.5. Secure the weight to the lever with a locking screw. If several IPUs are installed at the facility, install an additional weight on the lever to be able to adjust other IPUs.
4.6.6. Adjust the remaining IPUs in the same order.
4.6.7. Set the required pressure in the object and remove additional weights from the levers.
4.6.8. Make an entry about the adjustment carried out in the “Logbook of operation and repair of safety devices” (Form 1 of Appendix 5).
4.7. Direct-acting lever-weight valves are adjusted in the same order as the IPU.
4.8. Adjustment of the PPK should be done in the following order:
4.8.1. Install the valves on the stand (see Fig. 1), ensuring that the medium is removed from the valve to a safe place; Compress the spring to a gap between coils of 0.5 mm. For PCs produced by Krasny Kotelshchik JSC, the spring precompression value is indicated in the table. P4.14 of Appendix 4.
4.8.2. Open shut-off valve (valve) 1 completely and valve 3 partially (see Fig. 1); by gradually opening valve 2, ensure that air and water are displaced from under the PC and the stand is warmed up.
4.8.3. Guided by the requirements of the table, use valves 2 and 3 to set the required response pressure under the PC.
4.8.4. By rotating the PC adjusting sleeve counterclockwise, loosen the compression of the spring until the PC is activated.
4.8.5. Check the pressure at which the PC closes. It should not be lower than 0.8 R slave. If the closing pressure is less than 0.8 R slave, then you should check the position of the upper adjusting sleeve (damper sleeve) and the alignment of the chassis; if the PC closes with a delay at a pressure below 0.8 R slave, then the upper bushing should be lifted by rotating counterclockwise.
4.8.6. Raise the pressure again until the PC activates. Record this pressure. If necessary, adjust the response pressure by tightening or loosening the spring.
4.8.7. If it is necessary to adjust several PCs directly at the installation site, after adjusting the PC, write down the spring tension value that ensures the PC operates at a given pressure, and then tighten the spring to the original value N 1 and adjust the next PC. After completing the adjustment of all PCs to the values recorded after adjusting each PC, close the adjusting sleeve with a cap and seal the screws securing the cap to the yoke.
4.8.8. When installed on a protected object, IPUs equipped with IR with a spring load, they are adjusted in the same order as PPK.
5. PROCEDURE AND TIMELINES FOR CHECKING SAFETY VALVES
5.1. Checking the proper operation of the PC by purging should be done at least once every 6 months. At power plants equipped with boilers running on coal dust, the operation of the PC should be checked once every 3 months.
5.2. On equipment that is put into operation periodically (expanders of ignition separators, ROU, BROU, etc.), before each putting them into operation by forced opening, the IR IPU should be opened and an entry should be made about this in the “Operation and Repair Log of Safety Devices”.
It is allowed not to pace the IR if the interval between switching on the protected equipment does not exceed 1 month.
5.3. Checking the PC by blowing is carried out according to a schedule (Form 2 of Appendix 5), which is drawn up annually for each workshop, agreed with the operation inspector and approved by the chief engineer of the power plant.
5.4. If the test is carried out by raising the pressure to the activation setpoint of the PC, then each PC is checked one by one.
If, due to operating conditions, it is not possible to increase the pressure to the set point for the activation of the pressure switch, then it is permissible to check the pressure switch by manual detonation at operating pressure.
5.5. The check is carried out by the shift supervisor or senior driver and foreman repair organization repairing PCs.
The shift supervisor makes an entry about the inspection carried out in the “Logbook of operation and repair of safety devices.”
6. RECOMMENDATIONS FOR MONITORING THE CONDITION AND ORGANIZING REPAIR OF SAFETY VALVES
6.1. Scheduled monitoring of the condition and repair of PCs must be carried out at least once every 4 years according to a schedule based on the possibility of shutting down the equipment on which they are installed.
6.2. Monitoring the condition of the PC includes disassembling, cleaning and defective parts, checking the tightness of the valve, and the condition of the seals of the piston drive of the GPC.
6.3. Monitoring the condition and repairing PCs should be carried out in a specialized fitting workshop on special stands. The workshop should be well lit, should have lifting mechanisms and compressed air supply. The location of the workshop should ensure convenient transportation of the PC to the installation site.
6.4. Monitoring the condition and repairing PCs should be carried out by a permanent repair team that has experience in repairing fittings and has studied the design features of PCs and their operating conditions.
The team must be provided with PC working drawings, operation manuals, repair forms, spare parts and materials.
6.5. Before fault detection, parts of disassembled valves are cleaned of dirt and washed in kerosene.
6.6. When inspecting the sealing surfaces of the seat and plate, pay attention to the absence of cracks, dents, marks and other damage. When subsequently installed at the workplace, the sealing surfaces of the valve parts must have a cleanliness of at least 0.16. The quality of the sealing surfaces of the seat and disc must ensure their mutual fit in a closed ring, the width of the surface of which is at least 80% of the width of the smaller sealing surface.
6.7. The ellipse of the jackets of the GPC piston drives and guides should not exceed 0.05 mm per diameter. The surfaces in contact with the piston seals must have a roughness of 0.32.
6.8. When inspecting the GPC drive piston, special attention should be paid to the condition of the stuffing box. The packing rings must be tightly pressed together. There should be no damage to the working surface of the rings. Before assembly, it should be well graphiteized.
6.9. It is necessary to check the condition of the coil springs, for which it is necessary: to visually inspect the condition of the surface for the presence of cracks, deep marks, hairlines; measure the height of the spring in a free state and compare it with the requirements of the drawing; check the deviation of the spring from perpendicularity.
6.10. The condition of the threads of all fasteners and adjusting screws must be checked; All parts with defective threads must be replaced.
6.11. Repair and restoration of PC parts should be carried out in accordance with the current instructions for repairing fittings.
6.12. Before assembling the PC, you should check that the parts comply with the dimensions specified in the form or working drawings.
6.13. When assembling fastening joints, the nuts must be tightened evenly, without distortion of the parts being connected. In assembled PCs, the ends of the studs must protrude above the surface of the nuts by at least 1 thread pitch.
6.14. Tightening the oil seals in the piston chambers of the hydraulic pump should ensure the tightness of the piston, but should not impede its free movement.
7. ORGANIZATION OF OPERATION OF SAFETY VALVES
7.1. Overall responsibility for the condition, operation, repair and inspection of the control devices rests with the head of the workshop on whose equipment they are installed.
7.2. By order of the workshop, the workshop manager appoints persons responsible for checking PCs, organizing their repairs, and maintaining technical documentation.
7.3. Each workshop must maintain a “Logbook of operation and repair of safety devices,” which must include the following sections:
7.3.1. Statement of PC response pressure (Form 1 of Appendix 5).
7.3.2. Schedule for checking the serviceability of the PC by purging (Form 2 of Appendix 5).
7.3.3. Information about PC repair (form 3 of Appendix 5).
7.3.4. Information on forced testing of boiler PCs (Form 4 of Appendix 5).
7.4. Each PC must have a factory passport of the established type. If the TPP does not have a manufacturer's passport for each PC, it is necessary to draw up an operational passport (according to Form 5 of Appendix 5). The passport must be signed by the workshop manager and approved by the chief engineer of the thermal power plant.
7.5. For each group of PCs of the same type, the workshop must have an instruction manual (operation manual) and an assembly drawing of the PC, and for the PPK, an additional drawing or passport of the spring.
8. TRANSPORTATION AND STORAGE
8.1. PCs must be transported to the installation site in an upright position.
8.2. When unloading the PC from any type of transport, dropping it from platforms, improper construction, or installing the PC on the ground without pads is not allowed.
8.3. Valves should be stored in an upright position on pads in a dry, enclosed area. The inlet and outlet pipes must be closed with plugs.
9. SAFETY REQUIREMENTS
9.1. Safety devices must be installed in such a way that personnel performing adjustments and testing have the ability to quickly evacuate in the event of unexpected releases of the medium through leaks in the exit of rods from caps and flange connections.
9.2. Safety devices must be operated at pressure and temperature not exceeding the values specified in the technical documentation.
9.3. It is prohibited to operate and test the PU in the absence of outlet pipes that protect personnel from burns.
When eliminating defects, use wrenches larger in size than the size of the turnkey fasteners.
9.5. When testing IR IPU and direct-acting valves, the valve lever should be lifted slowly, away from places where the medium may be released from the valves. Personnel testing valves must have personal protective equipment: overalls, safety glasses, headphones, etc.
9.6. Preservation and depreservation of valves should be carried out in accordance with the manufacturer’s instructions, using individual funds protection.
9.8. It is prohibited to operate the PU in the absence of the information specified in section. 7 of this Instruction and technical documentation.
Russian FederationRD
RD 153-34.1-26.304-98 Instructions for the organization of operation, procedure and timing of inspection of safety devices of boilers of thermal power plants
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RD 153-34.1-26.304-98
SO 34.26.304-98
INSTRUCTIONS
ON ORGANIZATION OF OPERATION, PROCEDURE AND TIMELINES FOR CHECKING SAFETY DEVICES OF BOILERS OF THERMAL POWER PLANTS
Date of introduction 1999-10-01
DEVELOPED by the Open Joint Stock Company "Company for setting up, improving technology and operating power plants and networks ORGRES"
PERFORMER V.B. Kakuzin
AGREED with Gosgortekhnadzor of Russia on December 25, 1997.
APPROVED by the Department of Development Strategy and Scientific and Technical Policy of RAO UES of Russia on January 22, 1998.
First Deputy Chief D.L. BERSENEV
1. GENERAL PROVISIONS
1.1. This Instruction applies to safety devices installed on thermal power plant boilers.
1.2. The instructions contain the basic requirements for the installation of safety devices and determine the procedure for their regulation, operation and maintenance.
Appendix 1 sets out the basic requirements for boiler safety devices contained in the rules of the Gosgortekhnadzor of Russia and GOST 24570-81, provides technical characteristics and design solutions for boiler safety devices, and recommendations for calculating the throughput of safety valves.
The purpose of the Instruction is to help improve the safety of operation of thermal power plant boilers.
1.3. When developing the Instructions, the guidelines of the Gosgortekhnadzor of Russia, , , , , and data on operating experience of safety devices of thermal power plant boilers were used.
1.4. With the publication of this Instruction, the "Instructions for organizing the operation, procedure and timing of testing pulse safety devices of boilers with operating steam pressure from 1.4 to 4.0 MPa (inclusive): RD 34.26.304-91" and "Instructions for organizing operation, procedure and timing of inspection of impulse safety devices of boilers with steam pressure above 4.0 MPa: RD 34.26.301-91".
1.5. The following abbreviations are adopted in the Instructions:
PU- safety device;
PC- direct acting safety valve;
RGPC- direct-acting lever-load safety valve;
PPK- direct acting spring safety valve;
IPU- impulse safety device;
Civil Procedure Code- main safety valve;
IR- pulse valve;
CHZEM- JSC "Chekhov Power Engineering Plant";
TKZ- PA "Krasny Kotelshchik".
1.6. The methodology for calculating the throughput capacity of boiler safety valves, forms of technical documentation for safety devices, basic terms and definitions, designs and technical characteristics of safety valves are given in Appendices 2-5.
2. BASIC REQUIREMENTS FOR PROTECTING BOILERS FROM INCREASING PRESSURE ABOVE THE ALLOWABLE VALUES
2.1. Each steam boiler must be equipped with at least two safety devices.
2.2. The following may be used as safety devices on boilers with pressures up to 4 MPa (40 kgf/cm) inclusive:
direct-acting lever-weight safety valves;
Direct acting spring safety valves.
2.3. Steam boilers with steam pressure over 4.0 MPa (40 kgf/cm) must be equipped only with pulse-safety devices with an electromagnetic drive.
2.4. The passage diameter (conditional) of direct-acting lever-weight and spring valves and pulse valves IPU must be at least 20 mm.
2.5. The nominal diameter of the tubes connecting the pulse valve to the IPU GPK must be at least 15 mm.
2.6. Safety devices must be installed:
a) in steam boilers with natural circulation without a superheater - on the upper drum or steam chamber;
b) in direct-flow steam boilers, as well as in boilers with forced circulation - on the outlet manifolds or the outlet steam pipeline;
c) in hot water boilers - on the output collectors or drum;
d) in intermediate superheaters, all safety devices are on the steam inlet side;
e) in water-switched economizers - at least one safety device at the water outlet and water inlet.
2.7. If the boiler has a non-switchable superheater, part of the safety valves with a capacity of at least 50% of the total capacity of all valves must be installed on the outlet manifold of the superheater.
2.8. On steam boilers with an operating pressure of more than 4.0 MPa (40 kgf/cm), pulse safety valves (indirect action) must be installed on the outlet manifold of a non-switchable superheater or on the steam line to the main shut-off valve, while in drum boilers for 50% of the valves total throughput, steam selection for pulses should be made from the boiler drum.
If there is an odd number of identical valves, it is allowed to select steam for pulses from the drum for no less than 1/3 and no more than 1/2 of the valves installed on the boiler.
On block installations, if valves are placed on the steam pipeline directly next to the turbines, it is allowed to use superheated steam for impulses of all valves, while for 50% of the valves an additional electrical impulse must be supplied from a contact pressure gauge connected to the boiler drum.
If there is an odd number of identical valves, it is allowed to supply an additional electrical impulse from a contact pressure gauge connected to the boiler drum for no less than 1/3 and no more than 1/2 of the valves.
2.9. In power units with intermediate steam superheating, safety valves with a capacity of at least the maximum amount of steam entering the intermediate superheater must be installed after the turbine high-pressure cylinder (HPC). If there is a shut-off valve behind the HPC, additional safety valves must be installed. These valves must be calculated taking into account both the total capacity of the pipelines connecting the reheater system with higher pressure sources that are not protected by their safety valves at the entrance to the reheat system, and possible steam leaks that may occur if the high pressure steam and steam pipes are damaged. gas-steam heat exchangers for regulating steam temperature.
2.10. The total capacity of the safety devices installed on the boiler must be at least the hourly steam output of the boiler.
Calculation of the throughput capacity of boiler safety devices according to GOST 24570-81 is given in Appendix 1.
2.11. Safety devices must protect boilers, superheaters and economizers from increasing their pressure by more than 10%. Exceeding the steam pressure when the safety valves are fully open by more than 10% of the calculated value can only be allowed if this is provided for in the strength calculations of the boiler, superheater, or economizer.
2.12. The design pressure of safety devices installed on cold reheat pipelines should be taken as the lowest design pressure for low-temperature elements of the reheat system.
2.13. Sampling of the medium from the branch pipe or pipeline connecting the safety device to the protected element is not allowed.
2.14. The installation of shut-off devices on the steam supply line to the safety valves and between the main and pulse valves is not allowed.
2.15. To control the operation of the IPU, it is recommended to use an electrical circuit developed by the Teploelektroproekt Institute (Fig. 1), which provides for pressing the plate to the seat at normal pressure in the boiler due to the constant flow of current around the winding of the closing electromagnet.
Fig.1. Electrical diagram of the IPU
Note - The diagram is made for one pair of IPCs
For IPU installed on boilers with a nominal excess pressure of 13.7 MPa (140 kgf/cm) and below, by decision of the chief engineer of the thermal power plant, operation of the IPU without constant current flowing around the winding of the closing electromagnet is allowed. In this case, the control circuit must ensure that the IR is closed using an electromagnet and turned off 20 s after the IR is closed.
The IR solenoid control circuit must be connected to a backup DC source.
In all cases, only return keys should be used in the control scheme.
2.16. Devices should be installed in the connecting pipes and supply pipelines to prevent sudden changes in wall temperature (thermal shocks) when the valve is activated.
2.17. The internal diameter of the supply pipe must be no less than the maximum internal diameter of the supply pipe of the safety valve. The pressure drop in the supply pipeline to direct-acting safety valves should not exceed 3% of the valve opening pressure. In the supply lines of safety valves controlled by auxiliary devices, the pressure drop should not exceed 15%.
2.18. Steam from safety valves must be vented to a safe location. The internal diameter of the outlet pipe must be no less than the largest internal diameter of the outlet pipe of the safety valve.
2.19. The installation of a noise suppression device on the outlet pipeline should not cause a reduction in the capacity of the safety devices below the value required by safety conditions. When the outlet pipeline is equipped with a noise-attenuating device, a fitting for installing a pressure gauge must be provided immediately behind the valve.
2.20. The total resistance of the outlet pipelines, including the noise suppression device, must be calculated so that when the flow rate of the medium through it is equal to the maximum throughput of the safety device, the back pressure in the valve outlet pipe does not exceed 25% of the response pressure.
2.21. The outlet pipelines of safety devices must be protected from freezing and equipped with drains to drain condensate that accumulates in them. Installation of shut-off devices on drains is not permitted.
2.22. The riser (a vertical pipeline through which the medium is discharged into the atmosphere) must be securely fastened. In this case, the static and dynamic loads that arise when the main valve operates must be taken into account.
2.23. Temperature expansion compensation must be ensured in the safety valve pipelines. The fastening of the body and pipeline of safety valves must be designed taking into account static loads and dynamic forces that arise when the safety valves operate.
3. INSTRUCTIONS FOR INSTALLATION OF SAFETY DEVICES
3.1. Valve storage rules
3.1.1. Safety devices must be stored in places that prevent moisture and dirt from entering the internal cavities of the valves, corrosion and mechanical damage to parts.
3.1.2. Pulse valves with an electromagnetic drive must be stored in dry, enclosed areas free of dust and vapors that could cause destruction of the electromagnet windings.
3.1.3. The valves have a shelf life of no more than two years from the date of shipment from the manufacturer. If longer storage is required, the products must be re-preserved.
3.1.4. Loading, transporting and unloading of valves must be carried out in compliance with precautions to ensure they are not broken or damaged.
3.1.5. Subject to the above transportation and storage rules, the presence of plugs and the absence of external damage, the valves can be installed in the workplace without revision.
3.1.6. If transportation and storage rules are not followed, the valves should be inspected before installation. The issue of compliance of the storage conditions for valves with the requirements of the normative and technical documentation should be decided by a commission of representatives of the operational and repair departments of the thermal power plant and the installation organization.
3.1.7. When inspecting valves, you should check:
condition of the sealing surfaces of the valve.
After inspection, the sealing surfaces should have cleanliness = 0.32;
condition of gaskets;
condition of the seal packing of the servomotor piston.
If necessary, install new packing from pre-compressed rings. Based on the CHZEM tests, a combined seal consisting of a set of rings can be recommended for installation in the GPC servo drive chamber: two packages of rings made of graphite and metal foil and several rings made of thermally expanded graphite. (The seal is manufactured and supplied by JSC Unikhimtek, 167607, Moscow, Michurinsky Prospect, 31, building 5);
the condition of the piston working jacket in contact with the stuffing box; traces of possible corrosion damage to the shirt must be eliminated;
condition of the threads of fasteners (absence of nicks, burrs, chipping of threads);
condition and elasticity of springs.
After assembly, you should check the ease of movement of the moving parts and compliance of the valve stroke with the requirements of the drawing.
3.2. Placement and installation
3.2.1. Impulse safety devices must be installed in enclosed spaces.
The valves may be operated under the following environmental limits:
when using valves intended for delivery to countries with a temperate climate: temperature - +40 °C and relative humidity - up to 80% at a temperature of 20 °C;
when using valves intended for delivery to countries with tropical climates; temperature - +40 °C;
relative humidity - 80% at temperatures up to 27 °C.
3.2.2. The products included in the IPU kit must be installed in places that allow for their maintenance and repair, as well as assembly and disassembly on site without cutting out from the pipeline.
3.2.3. Installation of valves and connecting pipelines must be carried out according to working drawings developed by the design organization.
3.2.4. The main safety valve is welded to the fitting of the manifold or steam line with the stem strictly vertically upward. Deviation of the rod axis from the vertical is allowed no more than 0.2 mm per 100 mm of valve height. When welding a valve into a pipeline, it is necessary to prevent burr, splashes, and scale from entering their cavity and pipelines. After welding, the welds are subject to heat treatment in accordance with the requirements of the current instructions for the installation of pipeline equipment.
3.2.5. The main safety valves are attached with the paws available in the design of the products to a support, which must absorb the reactive forces that arise when the IPU is triggered. The exhaust pipes of the valves must also be securely fastened. In this case, any additional stress must be eliminated in the connection between the exhaust and the connecting flanges of the exhaust pipes. Constant drainage must be organized from the lowest point.
3.2.6. Pulse valves for fresh steam and reheat steam produced by LMZ, mounted on a special frame, must be installed on sites that are convenient for maintenance and protected from dust and moisture.
3.2.7. The pulse valve must be installed on the frame so that its stem is strictly vertical in two mutually perpendicular planes. The IR lever with a load and an electromagnet core suspended on it should not have distortions in the vertical and horizontal planes. To avoid jamming when opening the IR, the lower electromagnet must be located relative to the IR so that the centers of the holes in the core and lever are on the same vertical; the electromagnets must be located on the frame so that the axes of the cores are strictly vertical and located in a plane passing through the axes of the rod and the IR lever.
3.2.8. To ensure a tight fit of the IR plate on the saddle, the bar on which the clamp of the upper electromagnet rests must be welded so that the gap between the lower plane of the lever and the clamp is at least 5 mm.
3.2.9. When selecting pulses on an IR and an electric contact pressure gauge (ECM) from the same element on which the GPC is installed, the pulse sampling points must be at such a distance from the GPC that when it is triggered, the disturbance of the steam flow does not affect the operation of the IR and ECM (at least 2 m). The length of the impulse lines between the impulse and main valves should not exceed 15 m.
3.2.10. Electrical contact pressure gauges must be installed at the boiler service level. The permissible maximum ambient temperature in the ECM installation area should not exceed 60 °C. The shut-off valve on the medium supply line to the ECM must be open and sealed during operation.
4. PREPARATION OF VALVES FOR OPERATION
4.1. The compliance of the installed valves with the requirements of the design documentation and Section 3 is checked.
4.2. The tightness of the valve fasteners, the condition and quality of fit of the supporting surfaces of the prism of lever-load valves are checked: the lever and the prism must mate across the entire width of the lever.
4.3. The compliance of the actual stroke value of the hydraulic pump with the instructions of the technical documentation is checked (see Appendix 5).
4.4. In the GPK, reheat steam is moved by moving the adjusting nut along the stem to ensure a gap between its lower end and the upper end of the support disk, equal to the valve stroke.
4.5. For the reheat steam generator set produced by ChZEM, the screw of the throttle valve built into the cover is turned out by 0.7-1.0 turns,
4.6. The condition of the electromagnet cores is checked. They must be cleaned of old grease, rust, dust, washed with gasoline, ground and rubbed with dry graphite. The rod at the junction with the core and the core itself should not have distortions. The movement of the cores must be free.
4.7. The position of the damper screw of the electromagnets is checked. This screw should be screwed in so that it protrudes above the end of the electromagnet housing by approximately 1.5-2.0 mm. If the screw is completely screwed in, then when the armature rises, a vacuum is created under it, and with the electrical circuit de-energized, it is almost impossible to adjust the valve to operate at a given pressure. Over-tightening the screw will cause the core to move violently as it retracts, causing the sealing surfaces of the impulse valves to break.
5. ADJUSTING SAFETY DEVICES TO ACTIVATE AT A SET PRESSURE
5.1. Adjustment of safety devices to operate at a given pressure is carried out:
after installation of the boiler is completed;
after major repairs, if safety valves were replaced or overhauled (complete disassembly, grooving of sealing surfaces, replacement of chassis parts, etc.), and for PPK - in case of spring replacement.
5.2. To adjust the valves, a pressure gauge with an accuracy class of 1.0, tested in the laboratory using a standard pressure gauge, must be installed in close proximity to them.
5.3. Safety valves are regulated at the valve installation site by raising the pressure in the boiler to the response pressure.
Adjustment of spring safety valves can be done on a steam bench with operating parameters, followed by a control check on the boiler.
5.4. The actuation of the valves during adjustment is determined by:
for IPU - at the moment of activation of the GPC, accompanied by impact and loud noise;
for direct-acting full-lift valves - by a sharp pop observed when the spool reaches the top position.
For all types of safety devices, operation is controlled by the beginning of the pressure drop on the pressure gauge.
5.5. Before adjusting the safety devices, you must:
5.5.1. Make sure that all installation, repair and adjustment work is stopped on the systems in which the steam pressure necessary for regulation will be created, on the safety devices themselves and on their exhaust pipelines.
5.5.2. Check the reliability of disconnecting systems in which pressure will increase from adjacent systems.
5.5.3. Remove all bystanders from the valve adjustment area.
5.5.4. Ensure good lighting of PU installation workplaces, service areas and adjacent passages.
5.5.5. Establish two-way communication between valve adjustment points and the control panel.
5.5.6. Conduct instruction for shift and adjustment personnel involved in valve adjustment work.
Personnel must be well aware of the design features of the PUs being adjusted and the requirements of the instructions for their operation.
5.6. Direct-acting lever-load valves are adjusted in the following sequence:
5.6.1. The weights on the valve levers are moved to their extreme position.
5.6.2. In the protected object (drum, superheater), a pressure is established that is 10% higher than the calculated (permitted) one.
5.6.3. The weight on one of the valves is slowly moved towards the body until the valve is activated.
5.6.4. After closing the valve, the position of the weight is fixed with a locking screw.
5.6.5. The pressure in the protected object rises again and the pressure value at which the valve operates is checked. If it differs from that set in paragraph 5.6.2, the position of the weight on the lever is adjusted and the correct operation of the valve is re-checked.
5.6.6. After the adjustment is completed, the position of the weight on the lever is finally fixed with a locking screw. To prevent uncontrolled movement of the load, the screw is sealed.
5.6.7. An additional weight is installed on the lever of the adjusted valve and the remaining valves are adjusted in the same sequence.
5.6.8. After completing the adjustment of all valves in the protected object, the operating pressure is established. Additional weights are removed from the levers. A record is made in the Maintenance and Operation Log of safety devices about the readiness of the valves for operation.
5.7. Adjustment of direct acting spring safety valves:
5.7.1. The protective cap is removed and the height of the spring tension is checked (Table 6).
5.7.2. In the protected object, the pressure value is set in accordance with clause 5.6.2.
5.7.3. By turning the adjusting sleeve counterclockwise, the compression of the spring is reduced to the position at which the valve will operate.
5.7.4. The pressure in the boiler rises again and the pressure value at which the valve operates is checked. If it differs from that set according to clause 5.6.2, then the spring compression is adjusted and the valve is re-checked for operation. At the same time, the pressure at which the valve closes is monitored. The difference between the actuation pressure and the closing pressure should be no more than 0.3 MPa (3.0 kgf/cm). If this value is greater or less, then the position of the upper adjusting sleeve must be adjusted.
For this:
For TKZ valves, unscrew the locking screw located above the cover and turn the damper bushing counterclockwise to reduce the drop or clockwise to increase the drop;
For the PPK and SPPK valves of the Blagoveshchensk Valve Plant, the pressure difference between the actuation and closing pressures can be adjusted by changing the position of the upper adjusting sleeve, which is accessed through a hole closed with a plug on the side surface of the body.
5.7.5. The height of the spring in the adjusted position is recorded in the Journal of Repair and Operation of Safety Devices and it is compressed to a value so that the remaining valves can be adjusted. After completing the adjustment of all valves, the spring height recorded in the log in the adjusted position is set on each valve. To prevent unauthorized changes in the spring tension, a protective cap is installed on the valve, covering the adjusting sleeve and the end of the lever. The bolts securing the protective cap are sealed.
5.7.6. After the adjustment is completed, a record is made in the Maintenance and Operation Log of safety devices indicating that the valves are ready for operation.
5.8. Pulse safety devices with IR, equipped with an electromagnetic drive, are regulated to operate both from electromagnets and when the electromagnets are de-energized.
5.9. To ensure that the IPU is triggered by electromagnets, the ECM is configured:
5.9.1. The ECM readings are compared with the readings of a standard pressure gauge with a class of 1.0%.
5.9.2. The ECM is adjusted to turn on the opening electromagnet;
Where is the correction for water column pressure
Here is the density of water, kg/m;
Difference between the elevations of the place where the impulse line is connected to the protected object and the place where the ECM is installed, m.
5.9.3. The ECM is adjusted to turn on the closing electromagnet:
5.9.4. The limits of IR operation are marked on the ECM scale.
5.10. Adjusting the IR to operate at a given pressure with de-energized electromagnets is carried out in the same sequence as adjusting direct-acting lever-load valves:
5.10.1. The weights on the IR levers are moved to their extreme position.
5.10.2. The pressure in the boiler drum rises to the IPU response set point (); on one of the IR loads connected to the boiler drum, the load moves towards the lever to a position at which the IPU is triggered. In this position, the load is fixed to the lever with a screw. After this, the pressure in the drum rises again and it is checked at what pressure the IPU is triggered. If necessary, the position of the load on the lever is adjusted. After adjustment, the weights on the lever are secured with a screw and sealed.
If more than one IR is connected to the boiler drum, an additional weight is installed on the lever of the adjusted valve to allow adjustment of the remaining IR connected to the drum.
5.10.3. A pressure equal to the response pressure of the IPU behind the boiler () is set in front of the GPC. In the manner prescribed in clause 5.10.2, it is regulated for the operation of the IPU, in which the steam on the IR is taken behind the boiler.
5.10.4. After the adjustment is completed, the pressure behind the boiler is reduced to nominal and additional weights are removed from the IR levers.
5.11. Voltage is supplied to the electrical control circuits of the IPU. The valve control keys are set to the "Automatic" position.
5.12. The steam pressure behind the boiler is increased to the value at which the IPU should operate, and the opening of the gas pumps of all IPUs, the impulse to open which is taken behind the boiler, is checked locally.
When adjusting the IPU on drum boilers, the IPU control keys, triggered by a pulse behind the boiler, are set to the “Closed” position and the pressure in the drum rises to the IPU actuation set point. The operation of the GPK IPU, operating on an impulse from the drum, is checked locally.
5.13. Pulse-safety devices for reheat steam, which do not have shut-off elements behind them, are configured to operate after installation during the boiler firing for steam density. The procedure for setting the valves is the same as when setting the fresh steam valves installed behind the boiler (section 5.10.3).
If there is a need to adjust the reheat steam pulse valves after repairs, it can be done on a special stand. In this case, the valve is considered adjusted when the rise of the rod by the stroke value is recorded.
5.14. After checking the operation of the IPU, the control keys of all IPUs must be in the “Automatic” position.
5.15. After adjusting the safety devices, the shift supervisor must make an appropriate entry in the Maintenance and Operation Log of the safety devices.
6. PROCEDURE AND TIMELINES FOR CHECKING VALVES
6.1. Checking the proper operation of safety devices should be carried out:
when the boiler is stopped for scheduled repairs;
during boiler operation:
on pulverized coal boilers - once every 3 months;
on gas-oil boilers - once every 6 months.
During specified time intervals, the inspection should be timed to coincide with scheduled boiler shutdowns.
On boilers that are put into operation periodically, the check should be carried out during startup, if more than 3 or 6 months have passed, respectively, since the previous check.
6.2. Checking of the fresh steam IPU and reheat steam IPU, equipped with an electromagnetic drive, must be done remotely from the control panel with on-site response control, and the reheat steam IPU, which does not have an electromagnetic drive, by manually detonating the pulse valve at a unit load of at least 50% of the nominal load.
6.3. Testing of direct-acting safety valves is carried out at operating pressure in the boiler by alternately forcibly detonating each valve.
6.4. The inspection of safety devices is carried out by the shift supervisor (senior boiler operator) according to a schedule that is drawn up annually for each boiler based on the requirements of this Instruction, agreed with the operation inspector and approved by the chief engineer of the power plant. After the inspection, the shift supervisor makes an entry in the Maintenance and Operation Log of safety devices.
7. RECOMMENDATIONS FOR MONITORING THE CONDITION AND ORGANIZING REPAIR OF VALVES
7.1. Scheduled condition monitoring (inspection) and repair of safety valves are carried out simultaneously with the equipment on which they are installed.
7.2. Monitoring the condition of safety valves includes disassembling, cleaning and defective parts, checking the tightness of the valve, and the condition of the seal packing of the servo drive.
7.3. Condition monitoring and repair of valves must be carried out in a specialized valve workshop on special stands. The workshop must be equipped with lifting mechanisms, well lit, and have a compressed air supply. The location of the workshop should ensure convenient transportation of the valves to the installation site.
7.4. Monitoring the condition and repairing valves must be carried out by a repair team that has experience in repairing valves and has studied the design features of valves and the principle of their operation. The team must be provided with working drawings of the valves, repair forms, spare parts and materials for their quick, high-quality repair.
7.5. In the workshop, valves are disassembled and parts are defective. Before fault detection, parts are cleaned of dirt and washed in kerosene.
7.6. When inspecting the sealing surfaces of the valve seat and plate parts, pay attention to their condition (absence of cracks, dents, marks and other defects). During subsequent assembly, the sealing surfaces must have a roughness of =0.16. The quality of the sealing surfaces of the seat and plate must ensure their mutual contact, which ensures the mating of these surfaces along a closed ring, the width of which is not less than 80% of the width of the smaller sealing surface.
7.7. When inspecting the jackets of the servo drive piston chamber and guides, pay attention that the ellipse of these parts does not exceed 0.05 mm per diameter. The roughness of surfaces in contact with the stuffing box must correspond to cleanliness class = 0.32.
7.8. When inspecting the servo piston, special attention should be paid to the condition of the stuffing box. The rings must be tightly compressed together. There should be no damage to the working surface of the rings. Before assembling the valve, it should be well graphiteized.
7.9. The condition of the threads of all fasteners and adjusting screws must be checked. All parts with defective threads must be replaced.
7.10. You should check the condition of the coil springs, for which you should visually check the condition of the surface for cracks and deep scratches, measure the height of the spring in a free state and compare it with the requirements of the drawing, check the deviation of the spring axis from the perpendicular.
7.11. Repair and restoration of valve parts should be carried out in accordance with the current instructions for the repair of valves.
7.12. Before assembling the valves, check that the dimensions of the parts correspond to the dimensions specified in the form or working drawings.
7.13. Tightening the stuffing box rings in the piston chambers of the gas-piston chamber should ensure the tightness of the piston, but not impede its free movement.
8. ORGANIZATION OF OPERATION
8.1. Overall responsibility for the technical condition, inspection and maintenance of safety devices rests with the head of the boiler-turbine (boiler) shop on whose equipment they are installed.
8.2. The workshop order appoints persons responsible for checking valves, organizing their repair and maintenance, and maintaining technical documentation.
8.3. In the workshop, for each boiler, a log of repair and operation of safety devices installed on the boiler must be kept.
8.4. Each valve installed on the boiler must have a passport containing the following data:
valve manufacturer;
valve brand, type or drawing number;
nominal diameter;
serial number of the product;
operating parameters: pressure and temperature;
opening pressure range;
flow coefficient equal to 0.9 of the coefficient obtained on the basis of the valve tests;
calculated flow area;
for spring safety valves - the characteristics of the spring;
data on materials of main parts;
certificate of acceptance and conservation.
8.5. For each group of valves of the same type there must be: an assembly drawing, technical description and operating instructions.
9. SAFETY REQUIREMENTS
9.1. It is prohibited to operate safety devices in the absence of the documentation specified in paragraphs 8.4, 8.5.
9.2. It is prohibited to operate valves at pressures and temperatures higher than those specified in the technical documentation for the valves.
9.3. It is prohibited to operate and test safety valves in the absence of outlet pipes that protect personnel from burns when the valves operate.
9.4. Pulse valves and direct-acting valves must be located in such a way that during adjustment and testing there is no possibility of burns to operating personnel.
9.5. It is not allowed to repair valve defects if there is pressure in the objects to which they are connected.
9.6. When repairing valves, it is prohibited to use wrenches whose jaw size does not correspond to the size of the fasteners.
9.7. All types of repair and maintenance work must be carried out in strict compliance with fire safety regulations.
9.8. When the power plant is located in a residential area, the exhausts of the gas-processing complex IPU must be equipped with noise-attenuating devices that reduce the noise level when the IPU is activated to sanitary permissible standards.
Annex 1
REQUIREMENTS FOR BOILER SAFETY VALVES
1. The valves must open automatically at the specified pressure without fail.
2. In the open position, the valves should operate steadily, without vibration or pulsation.
3. Requirements for direct acting valves:
3.1. The design of a lever-load or spring safety valve must include a device for checking the proper operation of the valve during boiler operation by forcing the valve to open.
The possibility of forced opening must be ensured at 80% of the opening pressure.
3.2. The difference between the response pressure (full opening) and the beginning of the valve opening should not exceed 5% of the response pressure.
3.3. Safety valve springs must be protected from direct heat and direct exposure to the working environment.
When the valve is fully opened, the possibility of contact between the coils of the spring must be excluded.
3.4. The design of the safety valve should not allow arbitrary changes in its adjustment during operation. The RGPC must have a device on the lever that prevents the movement of the load. For PPK, the screw that regulates the spring tension must be closed with a cap, and the screws securing the cap must be sealed.
4. Requirements for IPU:
4.1. The design of the main safety valves must have a device that softens the shock when they open and close.
4.2. The design of the safety device must ensure that the functions of protection against overpressure are maintained in the event of failure of any control or regulatory body of the boiler.
4.3. The design of the safety device must allow it to be controlled manually or remotely.
4.4. The design of the device must ensure its automatic closing at a pressure of at least 95% of the operating pressure in the boiler.
Appendix 2
METHOD FOR CALCULATING THE CAPACITY OF BOILER SAFETY VALVES
1. The total capacity of all safety devices installed on the boiler must meet the following requirements:
for steam boilers
for hot water boilers
Where is the number of safety valves installed on the protected system;
Capacity of individual safety valves, kg/h;
Nominal steam output of the boiler, kg/h;
Nominal heating capacity of the hot water boiler, J/kg (kcal/kg);
Heat of evaporation, J/kg (kcal/kg).
Calculation of the throughput capacity of safety valves of hot water boilers can be carried out taking into account the ratio of steam and water in the steam-water mixture passing through the safety valve when it is activated
2. The capacity of the safety valve is determined by the formula;
For pressure in MPa;
For pressure in kgf/cm,
where is the valve capacity, kg/h;
The calculated cross-sectional area of the valve, equal to the smallest free cross-sectional area in the flow part, mm (must be indicated in the valve passport);
Steam consumption coefficient related to the calculated cross-sectional area (must be indicated by the factory in the valve passport or in the assembly drawing);
Maximum excess pressure in front of the safety valve, which should be no more than 1.1 design pressure, MPa (kgf/cm);
A coefficient that takes into account the physical and chemical properties of steam at operating parameters in front of the safety valve.
The values of this coefficient are selected from Tables 1 and 2 or determined using formulas.
At pressure in kgf/cm:
Where is the adiabatic exponent equal to:
1.135 - for saturated steam;
1.31 - for superheated steam;
Maximum excess pressure in front of the safety valve, kgf/cm;
Specific volume of steam in front of the safety valve, m/kg.
At pressure in MPa:
Table 1
Coefficient valuesfor saturated steam
table 2
Coefficient valuesfor superheated steam
Steam pressure, MPa (kgf/cm) | Coefficient at steam temperature, °C |
||||||||
To calculate the capacity of safety valves of power plants with fresh steam parameters:
13.7 MPa and 560 °C = 0.4;
25.0 MPa and 550 °C = 0.423.
The formula for determining valve capacity should only be used if:
For pressure in MPa;
For pressure in kgf/cm,
where is the maximum excess pressure behind the boiler in the space into which steam flows from the boiler (when flowing into the atmosphere = 0),
Critical pressure ratio.
For saturated steam =0.577.
For superheated steam =0.546.
Appendix 3
FORMS
TECHNICAL DOCUMENTATION ON BOILER SAFETY DEVICES, WHICH SHOULD BE MAINTAINED AT TPP
Statement
response pressure of boiler safety devices in the________ workshop
Boiler safety device inspection schedule
Boiler number | Established inspection frequency | Approximate timing for checking valves |
||||||||||||||||||||||||
Data
on scheduled and emergency repairs of boiler safety valves
Boiler N ____________
Appendix 4
BASIC TERMS AND DEFINITIONS
Based on the operating conditions of TPP boilers, taking into account the terms and definitions contained in various materials of the Gosgortekhnadzor of Russia, GOST and technical literature, the following terms and definitions are adopted in this Instruction.
1. Working pressure - the maximum internal excess pressure that occurs during the normal course of the working process without taking into account hydrostatic pressure and without taking into account the permissible short-term increase in pressure during the operation of safety devices.
2. Design pressure - excess pressure at which the strength of the boiler elements was calculated. For TPP boilers, the design pressure is usually equal to the operating pressure.
3. Permissible pressure - the maximum excess pressure allowed by accepted standards in the protected element of the boiler when the medium is discharged from it through a safety device
Safety devices must be selected and adjusted in such a way that the pressure in the boiler (drum) cannot rise above .
4. Opening pressure is the excess pressure at the valve inlet, at which the force aimed at opening the valve is balanced by the force holding the shut-off element on the seat.
Depending on the design of the valve and the dynamics of the process. But due to the rapidity of the actuation process, it is almost impossible to determine the number of lifting safety valves and IPUs when adjusting them.
5. Full opening pressure (operation pressure) - the maximum excess pressure that is established in front of the PC when it is fully opened. It should not exceed .
6. Closing pressure - excess pressure at which, after actuation, the shut-off element is seated on the seat.
For direct acting safety valves. An IPU with an electromagnetic drive must have at least .
7. Capacity - the maximum mass flow rate of steam that can be discharged through a fully open valve at response parameters.
Appendix 5
DESIGNS AND TECHNICAL CHARACTERISTICS OF BOILER SAFETY VALVES
1. Live steam impulse safety devices
1.1. Main safety valves
To protect boilers from increased pressure on fresh steam pipelines, GPC series 392-175/95-0, 392-175/95-0-01, 875-125-0 and 1029-200/250-0 are used. On old power plants with parameters of 9.8 MPa, 540 °C, valves of the 530 series are installed, and on blocks of 500 and 800 MW - series E-2929, which are currently out of production. At the same time, for newly designed boilers with parameters of 9.8 MPa, 540 °C and 13.7 MPa, 560 °C, the plant has developed a new valve design 1203-150/200-0, and for the possibility of replacing exhausted valves of the 530 series , which had a two-way steam outlet, valve 1202-150/150-0 is produced.
The technical characteristics of the produced ChZEM GPK are given in Table 3.
Table 3
Technical characteristics of the main safety valves IPU boilers
Valve designation | Nominal diameter, mm | Steam operating parameters | Smallest flow area, mm | Coef- | Steam consumption at operating parameters, t/h | The course of the class | Mas- |
||||
entrance- | You- | Pressure | Tempe- | for other | on the raft | ||||||
Fresh steam valves |
|||||||||||
1203-150/200-0-01 | |||||||||||
Reheat steam valves |
|||||||||||
111-250/400-0-01 | |||||||||||
Valves of series 392 and 875 (Fig. 2) consist of the following main components and parts: connecting inlet pipe 1, connected to the pipeline by welding; housing 2 with a chamber in which the servo drive 6 is located; plates 4 and saddles 3, making up the shutter assembly; lower 5 and upper 7 rods; hydraulic damper unit 8, in the housing of which a piston and spring are located.
Fig.2. 392 and 875 series main relief valves:
1 - connecting pipe; 2 - body; 3 - saddle; 4 - plate; 5 - lower rod; 6 - servo drive unit; 7 - upper rod; 8 - hydraulic damper chamber; 9 - housing cover; 10 - damper piston; 11 - damper chamber cover
The steam supply in the valve is carried out to the spool. Pressing it against the seat with pressure from the working medium increases the tightness of the valve. Pressing the plate to the seat in the absence of pressure under it is ensured by a spiral spring placed in the damper chamber.
The valve of the 1029-200/250-0 series (Fig. 3) is fundamentally designed like the valves of the 392 and 875 series. The only difference is the presence of a throttle grille in the body and the removal of steam through two oppositely directed outlet pipes.
Fig.3. 1029 Series Main Safety Valve
The valves work as follows:
when the PC is opened, steam flows through the impulse tube into the chamber above the servo piston, creating pressure on it equal to the pressure on the spool. But since the area of the piston, which is affected by steam pressure, exceeds the similar area of the spool, a shifting force arises, moving the spool down and thereby opening the discharge of steam from the object. When the pulse valve is closed, the access of steam to the servo chamber is stopped, and the steam present in it is discharged through the drain hole into the atmosphere.
In this case, the pressure in the chamber above the piston drops and due to the action of the medium pressure on the spool and the force of the spiral spring, the valve closes.
To prevent shocks when opening and closing the valve, its design includes a hydraulic damper in the form of a chamber located in the yoke coaxially with the servo drive chamber. The damper chamber contains a piston, which is connected to the spool using rods; According to the factory instructions, water or some other liquid of similar viscosity is poured or supplied into the chamber. When the valve opens, liquid flowing through small holes in the damper piston slows down the movement of the valve running gear and thereby softens the shock. When moving the valve running part towards closing, a similar process occurs in the opposite direction*. The valve seat is removable and is located between the connecting pipe and the body. The seat is sealed with comb metal gaskets. There is a hole in the side of the seat connected to the drainage system, into which the condensate that accumulates in the valve body after its operation is drained. To avoid vibration of the spool and breakage of the rod, guide ribs are welded into the connecting pipe.
________________
* As the operating experience of a number of thermal power plants has shown, the valves operate without shock even in the absence of liquid in the damper chamber due to the presence of an air cushion under and above the piston.
The peculiarity of the valves of the 1202 and 1203 series (Fig. 4 and 5) is that in them the connecting pipe is made integral with the body and there is no hydraulic damper, the role of which is played by the throttle 8 installed in the cover on the line connecting the above-piston chamber with the atmosphere.
Fig.4. 1202 series main relief valve:
1 - body; 2 - saddle; 3 - plate; 4 - servo drive unit; 5 - lower rod; 6 - upper rod; 7 - spring; 8 - throttle
Fig.5. 1203 Series Main Safety Valve
Just like the valves discussed above, valves of the 1203 and 1202 series operate on the principle of “loading”: when the IR is opened, the working medium is supplied to the above-piston chamber and, when a pressure in it reaches equal to , it begins to move the piston down, opening the discharge of the medium into the atmosphere.
The main parts of fresh steam valves are made of the following materials: body parts - steel 20KhMFL or 15KhMFL (540 °C), rods - steel 25Kh2M1F, spiral spring - steel 50KhFA.
The sealing surfaces of the valve parts are deposited with TsN-6 electrodes. Pressed rings made of asbestos-graphite cord grades AG and AGI are used as stuffing box packing. At a number of thermal power plants, a combined packing is used to seal the piston, including rings made of thermally expanded graphite, metal foil and foil made of thermally expanded graphite. The packing was developed by UNICHIMTEK and was successfully tested at ChZEM stands.
1.2. Pulse valves
All fresh steam IPUs manufactured by ChZEM are equipped with pulse valves of the 586 series. Technical characteristics of the valves are given in Table 4, and the design solution is shown in Fig. 6. The valve body is angular, with a flange connection between the body and the cover. A filter is mounted at the inlet of the valve, designed to capture foreign particles contained in the steam. The valve is driven by an electromagnetic drive, which is mounted on the same frame as the valve. To ensure that the valve operates when the voltage in the electromagnet power supply system disappears, a weight is suspended on the valve lever, by moving which you can adjust the valve to operate at the required pressure.
Table 4
Technical characteristics of pulse valves for fresh steam and reheat steam
Valve designation (drawing number) | Conditional passage, mm | Work Environment Settings | Test pressure during testing, MPa | Weight, kg |
||
Pressure, MPa | Tempe- | for strength | on density | |||
586-20-EMF-03 | ||||||
586-20-EMF-04 | ||||||
Fig.6. Fresh steam pulse valve:
A- valve design; b- installation diagram of the valve on the frame together with electromagnets
To ensure minimal inertia of the IPU operation, pulse valves should be installed as close as possible to the main valve.
2. Pulse-safety devices for reheating steam
2.1. Main safety valves
GPK ChZEM and LMZ 250/400 mm are installed on the cold reheating pipelines of boilers. The technical characteristics of the valves are given in Table 3, the design solution of the ChZEM reheat valve is shown in Fig. 7. The main components and parts of the valve are: bore type 1 body, connected to the pipeline by welding; a shutter assembly consisting of a seat 2 and a plate 3, connected via a thread to the rod 4; glass 5 with a servo drive, the main element of which is a piston 6 sealed with an stuffing box; spring load unit, consisting of two successively arranged spiral springs 7, the required compression of which is carried out by screw 8; throttle valve 9, designed to dampen the shock when closing the valve by regulating the rate of steam removal from the above-piston chamber. The seat is installed between the body and the glass on grooved gaskets and is crimped when tightening the cover fasteners. Centering of the spool in the seat is ensured by guide ribs welded to the spool.
Fig.7*. Main reheat steam safety valves of series 111 and 694:
1 - body; 2 - saddle; 3 - plate; 4 - rod; 5 - glass; 6 - servo piston; 7 - spring; 8 - adjusting screw; 9 - throttle valve; A - steam input from the pulse valve; B - release of steam into the atmosphere
* The quality of the drawing in electronic version corresponds to the quality of the drawing shown in the paper original. - Database manufacturer's note.
The main parts of the valves are made of the following materials: body and cover - steel 20GSL, upper and lower rods - steel 38ХМУА, spring - steel 50ХФА, stuffing box - cord AG or AGI. The sealing surfaces of the factory-made valve parts are welded with TsT-1 electrodes. The operating principle of the valve is the same as that of fresh steam valves. The main difference is the way the shock is damped when the valve closes. In the HPC reheat steam, the degree of shock damping is adjusted by changing the position of the throttle needle and tightening the spiral spring.
The main safety valves, intended for installation on the hot reheat line, series 694 differ from the cold reheat valves of the 111 series described above in the material of the body parts. The body and cover of these valves are made of 20ХМФЛ steel.
The GPKs supplied for installation on the cold reheat line, manufactured by LMZ (Fig. 8), are similar to the ChZEM series 111 valves, although they have three fundamental differences:
The servo piston is sealed using cast iron piston rings;
the valves are equipped with a limit switch, which allows information about the position of the shut-off element to be transmitted to the control panel;
There is no throttling device on the steam discharge line from the above-piston chamber, which eliminates the possibility of adjusting the degree of shock damping or valve closing and, in many cases, contributes to the occurrence of a pulsating mode of operation of the valves.
Fig.8. Main safety valve for reheat steam, designed by LMZ
2.2. Pulse valves
Lever-load valves 25 mm series 112 are used as pulse valves IPU ChZEM of the reheating system (Fig. 9, Table 4). The main parts of the valve: body 1, seat 2, spool 3, rod 4, sleeve 5, lever 6, weight 7. The seat is removable, installed in the body and, together with the body, in the connecting pipe. The spool is located in the inner cylindrical bore of the seat, the wall of which plays the role of a guide. The rod transmits force to the spool through the ball, which prevents the valve from skewing when the valve closes. The valve is set to operate by moving a weight on the lever and then locking it in a given position.
1 - body; 2 - plate; 3 - rod; 4 - guide sleeve; 5 - lifting sleeve; 6 - spring, 7 - pressure threaded bushing; 8 - cap; 9 - lever
Spring valves, full lift. They have a cast corner housing and are installed only in a vertical position in places with an ambient temperature not exceeding +60 °C. When the pressure of the medium under the valve increases, the plate 2 is pressed away from the seat, and the steam flow, flowing at high speed through the gap between the plate and the guide sleeve 4, has a dynamic effect on the lifting sleeve 5 and causes a sharp rise of the plate to a given height. By changing the position of the lifting sleeve relative to the guide sleeve, it is possible to find its optimal position, which ensures both sufficiently rapid opening of the valve and its closing with a minimal decrease in pressure relative to the operating pressure in the protected system. To ensure that when the valve opens, a minimum release of steam into the surrounding space is made in the valve cover, a labyrinth seal is made, consisting of alternating aluminum and paronite rings. Setting the valve to operate at a given pressure is carried out by changing the degree of tightening of spring 6 using a pressure threaded bushing 7. The pressure bushing is closed by a cap 8, secured with two screws. A control wire is passed through the screw heads, the ends of which are sealed.
To check the operation of the valves during operation of the equipment, a lever 9 is provided on the valve.
Technical characteristics of the valves, overall and connecting dimensions are given in Table 5.
Table 5
Technical characteristics of spring safety valves, old releases produced by PA "Krasny Kotelshchik"
Spring data | |||||||||||
Class code | Dia- | Working pressure | Maxi- | Coef- | Name- | Serial number of spring detail drawing | Dia- | External | Free spring height | Pressure | Mas- |
Version 1 | |||||||||||
Version 2 | |||||||||||
Version 3 | |||||||||||
3,5-4,5 (35-15)* | |||||||||||
Version 1 | |||||||||||
Version 2 | |||||||||||
Version 3 | |||||||||||
K-211947 | |||||||||||
K-211817 |
* Corresponds to the original. - Database manufacturer's note
The valve is currently available with a welded body. The technical characteristics of the valves and the springs installed on them are given in Tables 6 and 7.
Table 6
Technical characteristics of spring safety valves produced by Krasny Kotelshchik Production Association
Inlet flange | Outlet flange | Limit parameters of operating conditions | ||||||||||||
Class code | Us- | Conditions | Us- | Conditions | Wednesday | Working pressure, MPa/kgf/cm | Tempe- | Design diameter, mm | Opening start pressure, MPa**/kgf/cm | Designation | Spring designation | You- | Mas- | Coef- |
4.95±0.1/49.5±1 | ||||||||||||||
4.95±0.1/49.5±1 | ||||||||||||||
*Lower temperature is the limit for higher pressure. ** Limit of factory tests of valves for detonation. |
Table 7
Technical characteristics of springs installed on valves of the Krasny Kotelshchik Production Association
Geometric dimensions | ||||||||||
Spring designation | External | Dia- | Spring height at free | Step on- | Number of turns | Spring force at working deformation, kgf (N) | Working deformation | Expand | Weight, kg |
|
| (ST SEV 1711-79). Safety valves for steam and hot water boilers. Technical requirements.. - Database manufacturer's note. 8. Gurevich D.F., Shpakov O.N. Handbook of pipeline fittings designer. - L.: Mechanical Engineering, 1987. 9. Power fittings for thermal power plants and nuclear power plants. Industry catalog directory. - M.: TsNIITEITyazhmash, 1991. |
ADJUSTING SAFETY DEVICES TO ACTIVATE AT A SET PRESSURE
5.1. Adjustment of safety devices to operate at a given pressure is carried out:
after installation of the boiler is completed;
after major repairs, if safety valves were replaced or overhauled (complete disassembly, grooving of sealing surfaces, replacement of chassis parts, etc.), and for PPK - in case of spring replacement.
5.2. To adjust the valves, a pressure gauge with an accuracy class of 1.0, tested in the laboratory using a standard pressure gauge, must be installed in close proximity to them.
5.3. Safety valves are regulated at the valve installation site by raising the pressure in the boiler to the response pressure.
Adjustment of spring safety valves can be done on a steam bench with operating parameters, followed by a control check on the boiler.
5.4. The actuation of the valves during adjustment is determined by:
for IPU - at the moment of activation of the GPC, accompanied by impact and loud noise;
for direct-acting full-lift valves - by a sharp pop observed when the spool reaches the top position.
For all types of safety devices, operation is controlled by the beginning of the pressure drop on the pressure gauge.
5.5. Before adjusting the safety devices, you must:
5.5.1. Make sure that all installation, repair and adjustment work is stopped on the systems in which the steam pressure necessary for regulation will be created, on the safety devices themselves and on their exhaust pipelines.
5.5.2. Check the reliability of disconnecting systems in which pressure will increase from adjacent systems.
5.5.3. Remove all bystanders from the valve adjustment area.
5.5.4. Ensure good lighting of PU installation workplaces, service areas and adjacent passages.
5.5.5. Establish two-way communication between valve adjustment points and the control panel.
5.5.6. Conduct instruction for shift and adjustment personnel involved in valve adjustment work.
Personnel must be well aware of the design features of the PUs being adjusted and the requirements of the instructions for their operation.
5.6. Direct-acting lever-load valves are adjusted in the following sequence:
5.6.1. The weights on the valve levers are moved to their extreme position.
5.6.2. In the protected object (drum, superheater), a pressure is established that is 10% higher than the calculated (permitted) one.
5.6.3. The weight on one of the valves is slowly moved towards the body until the valve is activated.
5.6.4. After closing the valve, the position of the weight is fixed with a locking screw.
5.6.5. The pressure in the protected object rises again and the pressure value at which the valve operates is checked. If it differs from that set in paragraph 5.6.2, the position of the weight on the lever is adjusted and the correct operation of the valve is re-checked.
5.6.6. After the adjustment is completed, the position of the weight on the lever is finally fixed with a locking screw. To prevent uncontrolled movement of the load, the screw is sealed.
5.6.7. An additional weight is installed on the lever of the adjusted valve and the remaining valves are adjusted in the same sequence.
5.6.8. After completing the adjustment of all valves in the protected object, the operating pressure is established. Additional weights are removed from the levers. A record is made in the Maintenance and Operation Log of safety devices about the readiness of the valves for operation.
5.7. Adjustment of direct acting spring safety valves:
5.7.1. The protective cap is removed and the spring tension is checked h 1 (Table 6).
5.7.2. The pressure value in the protected object is set in accordance with clause 5.6.2.
5.7.3. By turning the adjusting sleeve counterclockwise, the compression of the spring is reduced to the position at which the valve will operate.
5.7.4. The pressure in the boiler rises again and the pressure value at which the valve operates is checked. If it differs from that set according to clause 5.6.2, then the spring compression is adjusted and the valve is re-checked for operation. At the same time, the pressure at which the valve closes is monitored. The difference between the actuation pressure and the closing pressure should be no more than 0.3 MPa (3.0 kgf/cm2). If this value is greater or less, then the position of the upper adjusting sleeve must be adjusted.
For this:
For TKZ valves, unscrew the locking screw located above the cover and turn the damper bushing counterclockwise to reduce the drop or clockwise to increase the drop;
For the PPK and SPPK valves of the Blagoveshchensk Valve Plant, the pressure difference between the actuation and closing pressures can be adjusted by changing the position of the upper adjusting sleeve, which is accessed through a hole closed with a plug on the side surface of the body.
5.7.5. The height of the spring in the adjusted position is recorded in the Journal of Repair and Operation of Safety Devices and it is compressed to the value h 1 to be able to adjust the remaining valves. After completing the adjustment of all valves, the spring height recorded in the log in the adjusted position is set on each valve. To prevent unauthorized changes in the spring tension, a protective cap is installed on the valve, covering the adjusting sleeve and the end of the lever. The bolts securing the protective cap are sealed.
5.7.6. After the adjustment is completed, a record is made in the Maintenance and Operation Log of safety devices indicating that the valves are ready for operation.
5.8. Pulse safety devices with IR, equipped with an electromagnetic drive, are regulated to operate both from electromagnets and when the electromagnets are de-energized.
5.9. To ensure that the IPU is triggered by electromagnets, the ECM is configured:
5.9.1. The ECM readings are compared with the readings of a standard pressure gauge with a class of 1.0%.
5.9.2. The ECM is adjusted to turn on the opening electromagnet:
Where h- correction for water column pressure
h= ρ D N· 10-5 MPa,
here ρ is the density of water, kg/m3;
D N- difference in marks between the place where the impulse line is connected to the protected object and the place where the ECM is installed, m.
5.9.3. The ECM is adjusted to turn on the closing electromagnet:
R zekm = 0.95 R p + h MPa.
5.9.4. The limits of IR operation are marked on the ECM scale.
5.10. Adjusting the IR to operate at a given pressure with de-energized electromagnets is carried out in the same sequence as adjusting direct-acting lever-load valves:
5.10.1. The weights on the IR levers are moved to their extreme position.
5.10.2. The pressure in the boiler drum rises to the IPU response set point ( R Wed = 1,1 R b); on one of the IR loads connected to the boiler drum, the load moves towards the lever to a position at which the IPU is triggered. In this position, the load is fixed to the lever with a screw. After this, the pressure in the drum rises again and it is checked at what pressure the IPU is triggered. If necessary, the position of the load on the lever is adjusted. After adjustment, the weights on the lever are secured with a screw and sealed.
If more than one IR is connected to the boiler drum, an additional weight is installed on the lever of the adjusted valve to allow adjustment of the remaining IR connected to the drum.
5.10.3. A pressure equal to the response pressure of the IPU behind the boiler ( R Wed = 1,1 R R) . In the manner prescribed in clause 5.10.2, it is regulated for the operation of the IPU, in which the steam on the IR is taken from the boiler.
5.10.4. After the adjustment is completed, the pressure behind the boiler is reduced to nominal and additional weights are removed from the IR levers.
5.11. Voltage is supplied to the electrical control circuits of the IPU. The valve control keys are set to the “Automatic” position.
5.12. The steam pressure behind the boiler is increased to the value at which the IPU should operate, and the opening of the gas pumps of all IPUs, the impulse to open which is taken behind the boiler, is checked locally.
When adjusting the IPU on drum boilers, the IPU control keys, triggered by a pulse behind the boiler, are set to the “Closed” position and the pressure in the drum rises to the IPU actuation set point. The operation of the GPK IPU, operating on an impulse from the drum, is checked locally.
5.13. Pulse-safety devices for reheat steam, which do not have shut-off elements behind them, are configured to operate after installation during the boiler firing for steam density. The procedure for setting the valves is the same as when setting the fresh steam valves installed behind the boiler (section 5.10.3).
If there is a need to adjust the reheat steam pulse valves after repairs, it can be done on a special stand. In this case, the valve is considered adjusted when the rise of the rod by the stroke value is recorded.
5.14. After checking the operation of the IPU, the control keys of all IPUs must be in the “Automatic” position.
5.15. After adjusting the safety devices, the shift supervisor must make an appropriate entry in the Maintenance and Operation Log of the safety devices.