Steam turbines general specifications for overhaul norms and requirements.
General information. The main and auxiliary steam turbine mechanisms (turbine generators, turbopumps, turbofans) are operated on ships of the navy; all of them undergo annual surveys during which: external inspection, readiness for action, operation in action, serviceability of maneuvering and starting devices and devices remote control, as well as the serviceability of the mounted and drive mechanisms is checked.
Maintenance steam turbine includes scheduled preventive inspections (PPO) and repairs (PPR), adjustment and tuning of turbine elements, troubleshooting, checking equipment for compliance with technical specifications, restoring lost properties, as well as taking measures to preserve turbines when they are inactive.
Depending on the volume and nature of the work performed, maintenance is divided into daily, monthly and annual.
Daily maintenance includes the following main operations:
- visual inspection;
- removal of leaks of fuel, oil and water;
- removal of traces of corrosion;
- vibration measurement.
Dismantling and dismantling of turbines. According to the manufacturer's instructions, scheduled openings of the turbines are carried out. The purpose of opening turbines is to assess the technical condition of parts, clean their flow path from corrosion, carbon deposits and scale.
The dismantling of the turbine is started no earlier than 8-12 hours after it stops, that is, after cooling, when the temperature of the casing walls becomes equal to the ambient temperature (about 20 C).
If the turbine is dismantled for transportation to the workshop, then the following procedure for dismantling is observed:
- disconnect the turbine from the incoming steam;
- drain or pump out water from the condenser;
- pump out oil from the turbine or lower it, freeing the oil system;
- remove fittings and instrumentation;
- disconnect pipelines directly connected to the turbine, or interfering with its dismantling from the foundation;
- remove the turbine casing and insulation;
- disassemble handrails, remove platforms and shields;
- remove the quick-closing valve of the receiver and bypass valves;
- disengage the turbine rotor from the gearbox;
- start slings and fix them to the load-lifting device;
- give the foundation bolts and remove the turbine from the foundation. Undermining the stator cover is carried out with forcing bolts, and lifting
(lowering) it and the rotor are made with a special device. This device consists of four screw columns and lifting mechanisms. Rulers are fixed on the screw columns to control the lifting height of the stator cover or turbine rotor. When lifting the cover or rotor, every 100-150 mm make a stop and check the uniformity of their rise. The same is true when lowering them.
Defectoscopy and repair. Turbine flaw detection is performed in two stages: before opening and after opening during disassembly. Before opening the turbine, using standard instrumentation, the following are measured: axial run-up of the rotor in the thrust bearing, oil clearances in the bearings, clearances in the speed limiter.
Typical defects of a steam turbine include: deformation of the stator connector flanges, cracks and corrosion of the internal cavities of the stator; deformation and imbalance of the rotor; deformation of the working disks (weakening of their fit on the rotor shaft), cracks in the area of the keyways; erosive wear, mechanical and fatigue destruction of rotor blades; diaphragm deformation; erosion wear and mechanical damage to the nozzle apparatus and guide vanes; wear of rings of end and intermediate seals, bearings.
During the operation of the turbine, thermal deformations of parts mainly occur, caused by violations of the Rules technical operation.
Thermal deformations occur as a result of uneven heating of the turbine during its preparation for start-up and when it is stopped.
The operation of an unbalanced rotor causes vibration of the turbine, which can lead to blade and shroud breakage, to destruction of seals and bearings.
Steam turbine housing performed with a horizontal connector that divides it into two halves. The bottom half is the body and the top half is the lid.
The repair consists in restoring the density of the body parting plane due to warpage. Warping of the parting plane with gaps up to 0.15 mm is eliminated by scraping. After scraping is completed, the cover is put back in place and the presence of local gaps is checked with a probe, which should not be more than 0.05 mm. Cracks, fistulas and corrosion pits in the turbine housing are cut and repaired by welding and surfacing.
Steam turbine rotors. In the main turbines, the rotors are most often made of one-piece forged, while in the auxiliary turbines, the rotor is usually prefabricated, consisting of a turbine shaft and impeller.
The deformation of the rotor (bending), which does not exceed 0.2 mm, is removed by machining, up to 0.4 mm - by thermal straightening, and more than 0.4 mm - by thermomechanical straightening.
The cracked rotor is replaced. The wear of the necks is eliminated by grinding. The ovality and cone shape of the necks is allowed no more than 0.02 mm.
working disks. Cracked discs are replaced. The deformation of the discs is detected by end runout and, if it does not exceed 0.2 mm, it is eliminated by turning the end of the disc on the machine. With a larger amount of deformation, the disks are subjected to mechanical straightening or replacement. The weakening of the fit of the disk on the shaft is eliminated by chrome plating of its mounting hole.
Disc blades. Erosive wear is possible on the blades and, if it does not exceed 0.5-1.0 mm, then they are filed and polished by hand. In case of large damage, the blades are replaced. New blades are made at turbo-building plants. Before installing new blades, they are weighed.
In the presence of mechanical damage and separation of the band bandage of the working blades, it is replaced, for which the old bandage is removed.
Turbine diaphragms. Any diaphragm consists of two halves: upper and lower. The upper half of the diaphragm is installed in the housing cover, and the lower half is installed in the lower half of the turbine housing. The repair is associated with the elimination of distortion of the diaphragm. The warping of the diaphragm is determined on the plate with probe plates; for this, the diaphragm is placed with a rim on the side of the steam outlet on the plate and the presence of gaps between the rim and the plate is checked with a probe.
Warping is eliminated by grinding or scraping the end of the rim along the plate onto the paint. Then, along the scraped end of the diaphragm rim, a landing groove in the turbine housing is scraped from the side of the steam outlet. This is done to achieve a snug fit of the diaphragm to the body, in order to reduce steam leakage. If there are cracks on the rim of the diaphragm, it is replaced.
Labyrinth (end) seals. By design, labyrinth seals can be of a simple type, elastic fir-tree type, elastic comb type. When repairing seals, bushings and segments of labyrinth seals with damage are changed by setting radial and axial clearances in accordance with the repair specifications.
Support bearings in turbines can be sliding and rolling. Sleeve bearings are used in the main marine steam turbines. The repair of such bearings is similar to the repair of diesel bearings. The value of the adjusting oil clearance depends on the diameter of the rotor shaft neck. With a shaft neck diameter of up to 125 mm, the installation gap is 0.12-0.25 mm, and the maximum allowable gap is 0.18-0.35 mm. Rolling bearings (ball, roller) are installed in the turbines of auxiliary mechanisms and they are not subject to repair.
Static balancing of discs and rotors. One of the causes of turbine vibration is the imbalance of the rotating rotor and disks. Rotating parts may have one or more unbalanced masses. Depending on their location, static or dynamic unbalance of the masses is possible. Static imbalance can be determined statically, without rotating the part. Static balancing is the alignment of the center of gravity with its geometric axis of rotation. This is achieved by removing metal from the heavy part of the part or adding it to its light part. Before balancing, the radial runout of the rotor is checked, which should be no more than 0.02 mm. Static balancing of parts operating at a speed of up to 1000 min-1 is carried out in one stage, and at a higher speed - in two stages.
At the first stage, the part is balanced to its indifferent state, in which it stops in any position. This is achieved by determining the position of the heavy point, and then picking up and attaching a balancing weight from the opposite side.
After balancing the part on its light side, instead of a temporary load, a permanent load is fixed, or an appropriate amount of metal is removed from the heavy side and the balancing is completed.
The second stage of balancing is to eliminate the residual imbalance (imbalance) remaining due to the inertia of the part and the presence of friction between them and the supports. For this, the surface of the end face of the part is divided into six to eight equal parts. Then, the part with a temporary load is installed so that it is in a horizontal plane (point 1). At this point, the mass of the temporary load is increased until the part is out of balance and begins to rotate. After this operation, the load is removed and weighed on the scales. In the same sequence, work is performed for the remaining points of the part. Based on the data obtained, a curve is built, which, if balancing is performed accurately, should have the shape of a sinusoid. The maximum and minimum points are found on this curve. The maximum point of the curve corresponds to the light part of the part, and the minimum point corresponds to the hard part. The accuracy of static balancing is estimated by the inequality:
where To is the weight of the balancing load, g;
R- radius of installation of temporary cargo, mm;
G— weight of the rotor, kg;
Lst— the maximum allowable displacement of the center of gravity of the part from its axis of rotation, microns. The maximum allowable displacement of the center of gravity of the part is found from the diagram of the maximum allowable displacements of the center of gravity during static balancing, according to the passport data of the turbine or by the formula:
where n— rotor speed, s-1.
dynamic balancing. During dynamic balancing, all masses of the rotor are reduced to two masses lying in the same diametral plane, but on opposite sides of the axis of rotation. Dynamic unbalance can only be determined by the centrifugal forces that occur when the part rotates at a sufficient speed. The quality of dynamic balancing is estimated by the magnitude of the amplitude of the oscillations of the rotor at the critical frequency of its rotation. Balancing is carried out on a special stand in the factory. The stand has pendulum or swing type supports (types of stands 9V725, 9A736, MS901, DB 10, etc.). The turbine rotor is placed on two springy bearings mounted on the frame supports and connected to the electric motor. By rotating the turbine rotor with an electric motor, its critical speed is determined, while measuring in turn the maximum oscillation amplitudes of the rotor necks on each side. Then, each side of the rotor is marked around the circumference into 6-8 equal parts and the mass of the test load is calculated for each side. Balancing starts from the side of the bearing, which has a large oscillation amplitude. The second bearing is fixed. The test load is fixed at point 1 and the maximum amplitude of oscillations of the rotor neck is measured at the critical frequency of its rotation. Then the load is removed, fixed at point 2, and the operation is repeated. Based on the data obtained, a graph is built, according to which the maximum and minimum amplitudes and the average value of the amplitude are determined, and according to its value, the mass of the balancing load. The bearing with the larger oscillation amplitude is fixed, and the second one is released from the mounting. The balancing operation of the second side is repeated in the same sequence. The balancing results are evaluated according to the inequality:
where aoct— oscillation amplitude of the rotor ends, mm;
R— radius of fastening of the balancing weight, mm;
G- part of the mass of the rotor attributable to this support, kg;
Lct— allowable displacement of the center of gravity from the axis of rotation of the rotor during dynamic balancing, microns.
Turbine assembly includes centering of the rotor and diaphragms.
Rotor alignment. Before centering the rotor, slide bearings are adjusted along the beds and necks of the rotor. Then the rotor is centered relative to the axis of the bore for the holders of the end seals of the turbine. During the alignment of the rotor and diaphragms, a false shaft (technological shaft) is used, which is placed on bearings. Then the gaps between the shaft neck and the cylindrical surface under the seals are measured in the vertical and horizontal planes. Permissible displacement of the rotor axis relative to the axis of the bores for seals is allowed up to 0.05 mm. The equality of the gaps indicates good centering, and if not, then the centering of the rotor axis is performed.
Turbine shutdown. Before laying the rotor, its necks and bearings are lubricated with clean oil. Then the rotor is placed on bearings and the cover is lowered. After crimping the cover, the ease of rotation of the rotor is checked. To seal the separation planes of the turbine, operating at pressures above 3.5 MPa and temperatures up to 420 ° C, “Sealant” paste or other mastics are used. At the same time, the threads of nuts, studs and simple bolts are coated with a thin layer of graphite, and tight bolts are lubricated with mercury ointment.
Turbine testing after repair. The repaired turbomechanisms should be tested first at the SRZ stand, then mooring and sea trials should be carried out. In the absence of stands at the shipyard, turbomechanisms are subjected only to mooring and sea trials. Mooring tests consist of run-in, adjustment and testing of turbomechanisms according to the program of bench tests.
All preparations for the trial run of the turbine plant (checking the operation of valves, heating the turbine and steam pipelines, lubrication system, etc.) are carried out in full accordance with the "Rules for the maintenance and care of marine steam turbines". In addition, the lubrication system and bearings are pumped with hot oil at a temperature of 40-50 C using a lubrication pump. To clean the lubrication system from contamination, temporary filters made of copper mesh and gauze, etc. are installed in front of the bearings. They are periodically opened, washed and put back in place. Pump the oil until there is no sediment on the filters. After pumping, the oil is drained from the supply tank, the tank is cleaned and filled with fresh oil.
Before starting, the turbine is rotated with a barring device, while carefully listening with a stethoscope to the location of the bearings of the turbine and gearbox, the area of the flow path, seals and gears. In the absence of any remarks, the turbine rotor is rotated with steam, bringing its rotation to a frequency of 30-50 min -1, and the steam is immediately blocked. The secondary start-up of the turbine is carried out if no malfunctions are found during cranking.
With any extraneous sound in the turbine, it is immediately stopped, inspected, the causes of malfunctions are identified and measures are taken to eliminate them.
The operation of the turbomechanism at idle is checked with a gradual increase in the turbine rotor speed to the nominal value and, at the same time, the operation of the speed controller, quick-closing valve, vacuum condenser, etc.
During sea trials, the technical and economic indicators of the turbomechanism are determined in all operating modes.
It must be organized in strict accordance with the requirements of the manufacturer's instructions, the rules of technical operation, fire safety and safety precautions when servicing the thermal mechanical equipment of power plants and networks, by specialists trained for this work.
At each power plant, in accordance with the above materials, local operating instructions for turbines are developed outlining the rules for starting, stopping, shutting down, possible malfunctions on the equipment of the turbine unit and the procedure for their prevention and elimination, which are mandatory for maintenance personnel.
Problems that prevent the turbine from starting.
Despite the differences in turbine designs, schemes, auxiliary equipment, there is a common
all the list of defects and malfunctions that must be eliminated before start-up.
Turbine start is prohibited:
- in the absence or malfunction of the main instruments that control the flow of the thermal process in the turbine and its mechanical condition (pressure gauges, thermometers, vibrometers, tachometers, etc.);
- in case of a faulty, i.e. the oil tank must be inspected (oil level, pointer
level), oil coolers, oil pipelines, etc.;
- in case of a fault in all circuits that stop the supply of steam to the turbine. The entire protection chain is checked from sensors to actuators (axial shift relay, vacuum relay, safety switch, atmospheric valves, shut-off and control valves, shut-off valves on steam pipelines of live steam, selections);
- in case of a fault;
- with a faulty turning device. Supplying steam to a stationary rotor can cause it to bend.
Turbine startup preparation.
The turbine start-up technology depends on its temperature state. If the temperature of the turbine metal (high pressure casing) is below 150 °C, then it is considered that the start-up is carried out from a cold state. It takes at least three days after its stop.
Starting from a hot state corresponds to a turbine temperature of 400 ° C and above.
At intermediate value temperature is considered to be cold start.
The basic principle of the launch is to be carried out at the maximum possible speed according to the conditions of reliability (do no harm).
The main feature of the start-up of a non-block turbine (TPP with cross-links) is the use of steam with nominal parameters.
The start-up of the turbine consists of three stages: preparatory, a turnaround period with bringing the speed to full (3000 rpm) and synchronization (connection to the network) and subsequent loading.
During the preparatory period, the general condition of all equipment of the turbine plant, the absence of unfinished work, the serviceability of instruments and alarms are checked. Heating of the steam pipeline and bypass pipes lasts 1-1.5 hours. At the same time, the water supply to the condenser is prepared. The operation of all oil pumps is checked (except for the HMN - on the turbine shaft), the starting oil pump is left in operation and the barring device is turned on. The protection and regulation systems are checked with the main steam valve (MSV) closed and the absence of steam pressure in front of the shut-off valve. Vacuum starts. the control mechanism is brought to the minimum position, the automatic safety device is cocked, the drains of the turbine housing are opened.
Turbine thrust.
The impetus of the rotor (bringing it into rotation) is produced either by opening the first control valve, or by the GPZ bypass with fully open control valves.
The turbine is maintained at low speeds (500-700), thermal expansions are checked, seals, housings, bearings are tapped with a stethoscope, instrument readings for oil, temperature, pressure, relative expansions.
The critical frequencies of the shafting must be passed quickly and after inspecting all the elements of the turbine and in the absence of deviations from the norms, you can go for a U-turn, constantly listening to the turbine. In this case, the temperature difference between the top and bottom of the cylinder should not exceed 30-35 °C, between the flange and the stud - no more than 20-30 °C. Upon reaching 3000 rpm, the turbine is inspected, the protection and control systems are checked, manual and remote shutdown of the turbine is tested. The control mechanism checks the smoothness of movement of the control valves, checks the operation of the automatic safety device by supplying oil to the strikers, and if necessary (it is required by the rules) and increasing the number of revolutions.
If there are no comments, the signal “Attention! Ready". After the generator is connected to the network, the turbine is loaded according to the instructions.
Starting turbines with backpressure.
Parameters are subject to special control, the deviation of which beyond the permissible limits threatens the reliable operation of the turbine - this is the relative elongation of the rotor and its axial shift, the vibrational state of the unit.
The parameters of fresh steam, after and inside the turbine, oil in the control system and lubrication are constantly monitored, preventing heating of the bearings, and the operation of seals.
The operating instructions define the vacuum, temperature feed water, cooling water heating, temperature difference in the condenser and subcooling of the condensate, as the economical operation of the turbine depends on this. It has been established that the deterioration of the operation of regenerative heaters and the undercooling of feed water by 1 °C leads to an increase specific consumption heat by 0.01%.
The flow part of the turbine is prone to drifting with salts contained in the steam. Salt drift, in addition to reducing efficiency, worsens the reliability of the blade apparatus and the turbine as a whole. To clean the flow part, washing with wet steam is carried out. But this is a very responsible, and therefore undesirable operation.
Normal operation of the turbine is unthinkable without careful monitoring, maintenance and regular checks of protection and regulation systems, therefore, a constant thorough inspection of the nodes and elements of regulation, protection, steam distribution bodies is necessary, paying attention to oil leaks, fasteners, locking devices; move stop and control valves.
According to the PTE, within the time limits established by the instructions, the strikers of the safety machine should be regularly tested by pouring oil and increasing the turbine speed, and the tightness of stop, control and check valves should be checked. Moreover, it is necessary after installation, before and after major repairs. The stop and control valves may not be completely tight, but closing them together should prevent the rotor from turning.
Turbine stop.
When shutting down the turbine to hot standby, it is desirable to keep the temperature of the metal as high as possible. Shutdown with cooldown is carried out when the turbine is put into a long-term reserve or for major and current repairs.
Before the shutdown, at the direction of the station shift supervisor, according to the instructions, the turbine is unloaded with the controlled extraction and regeneration turned off.
Having reduced the load to 10-15% of the nominal one and having received permission, by acting on the shutdown button, the steam supply to the turbine is stopped. From this point on, the turbine is rotated by the electrical network, i.e. generator is running in engine mode. In order to avoid heating the tail of the turbine, it is necessary to quickly make sure that the shut-off, control and check valves on the extraction lines are closed, and the wattmeter indicates negative power, because. the generator consumes power from the network during this period. After that, the generator is disconnected from the network.
If, due to leaky valves, their freezing, or for other reasons, steam enters the turbine and there is a load on the unit according to the wattmeter, then it is strictly forbidden to disconnect the generator from the network, since the steam entering the turbine may be sufficient to accelerate it.
It is urgently necessary to close the main steam valve (GPP), its bypass, tighten the valves on the extractions, it is possible to tap the valves, make sure that steam does not enter the turbine, and only then the generator is disconnected from the network.
When unloading the turbine, it is necessary to carefully monitor the relative contraction of the rotor, avoiding dangerous limits.
After the turbine is switched to idle, all the tests necessary according to the instructions are carried out. After the turbogenerator is disconnected from the network, the rotor begins to run, at which the rotational speed decreases from the nominal to zero. This rotation occurs due to the inertia of the shafting. It should be noted that the weight of the rotating parts of the T-175 turbine, together with the generator and exciter rotors, is 155 tons.
Rotor runout is an important operational indicator that allows you to judge the condition of the unit.
Be sure to remove the run-out curve - the dependence of the speed on time. Depending on the power, the overrun is 20-40 minutes. With a deviation of 2-3 minutes, you need to look for the cause and eliminate it.
After the rotor stops, the barring device (VPU) is immediately turned on, which should work until the temperature of the turbine metal drops below 200 °C.
During and after the coastdown, all other operations are performed for oil, circulating water, etc. according to instructions.
Turbine emergency stop.
In case of occurrence on the turbine unit emergency it is necessary to act in accordance with the emergency instructions, which defines a list of possible emergency situations and measures to eliminate them.
When eliminating an emergency, you need to carefully monitor the main indicators of the turbine:
— frequency of rotation, load;
are the live steam parameters and ;
— vacuum in the condenser;
— vibration of the turbine unit;
- axial shift of the rotor and the position of the rotors relative to their housings;
— oil level in the oil tank and its pressure in control and lubrication systems, oil temperature at the inlet and outlet of the bearings, etc.
The emergency instruction defines the methods of emergency shutdown depending on emergency circumstances - without vacuum breakdown and with vacuum breakdown, when atmospheric air is let in into the turbine exhaust and condenser by opening the valve.
The emergency shutdown of the turbine unit is carried out by immediately stopping the supply of fresh steam to the turbine with the emergency stop button or by remotely acting on the electromagnetic switch, and, after making sure that the turbine is turned off and does not carry a load, a signal is sent to the main control panel “Attention! The car is in danger! After that, the generator is disconnected from the network. Be sure to close the main steam valve (GPZ), its bypass and valves at the selections.
Further shutdown operations are carried out in the usual way.
Vacuum breakdown is performed when it is necessary to accelerate the stop of the rotor, for example, with a sharp decrease in the oil level, with water hammer in the turbine, sudden strong vibration, with a sharp axial shift of the rotor, etc.
When stopping without breaking the vacuum, the rotor of the K-200-130 turbine stops in 32–35 minutes, and when the vacuum breaks, it takes 15 minutes, but during this operation, the exhaust pipe heats up due to a sharp increase in the density of the medium, which leads to the braking of the rotor. Therefore, the shutdown of the turbine with a breakdown of the vacuum is carried out only in cases specified by the emergency instructions.
n1.doc
Ministry of Education Russian FederationGOU Ural State Technical University - UPI
V. N. Rodin, A. G. Sharapov, B. E. Murmansky, Yu. A. Sakhnin, V. V. Lebedev, M. A: Kadnikov, L. A. Zhuchenko
REPAIR OF STEAM TURBINES
Tutorial
Under the general editorship of Yu. M. Brodov V. N. Rodin
Yekaterinburg 2002
SYMBOLS AND ABBREVIATIONS
TPP - thermal power plant
NPP - nuclear power plant
PPR - scheduled preventive maintenance
NTD - normative and technical documentation
PTE - rules of technical operation
STOIR - maintenance and repair system
SAR - automatic control system
ERP - energy repair company
CCR - centralized repair shop
RMU - mechanical repair department
RD - guiding document
OPPR - department of preparation and carrying out repairs
KIP - instrumentation
LMZ - Leningrad Mechanical Plant
HTZ - Kharkov Turbine Works
TMZ - Turbo engine plant
VTI - All-Union Thermal Engineering Institute
HPC - high pressure cylinder
TsSD - medium pressure cylinder
LPC - low pressure cylinder
HDPE - low pressure heater
PVD - high pressure heater
KTZ - Kaluga Turbine Works
MPD - magnetic particle flaw detection
UT - ultrasonic testing
Central Design Bureau "Energoprogress" - Central Design Bureau "Energoprogress"
VPU - barring device
RVD - high pressure rotor
RSD - medium pressure rotor
RND - low pressure rotor
HP - part of the high pressure
HR - part of the average pressure
LPH - low pressure part
TV K - eddy current control
CD - color flaw detection
QCD - department of technical control
TU - technical conditions
MFL - metal-fluoroplastic tape
LFV - low frequency vibration
GPZ - main steam valve
ZAB - spool of automatic safety device
Efficiency - efficiency factor
KOS - solenoid check valve
WTO - reducing heat treatment
HERE. - tons of reference fuel
H.H. - idling
FOREWORD
Energy, as a basic industry, determines the "health" of the country's economy as a whole. The state of affairs in this branch of industry has become more complicated in recent years. This is determined by a number of factors:
underloading of equipment, which, as a rule, leads to the need to operate turbines (and other TPP equipment) in modes that do not correspond to maximum efficiency;
a sharp reduction in the commissioning of new capacities at TPPs;
moral and physical old age almost 60% of power equipment;
limited supplies and a sharp increase in the cost of fuel for thermal power plants;
lack of funds for the modernization of equipment and others.
In the blocks of special disciplines of standards and curricula of most energy and power engineering specialties of universities, the discipline "Repair of steam turbines", unfortunately, is absent. In a number of fundamental textbooks and manuals on steam turbines, practically no attention is paid to the issues of their repair. A number of publications do not reflect the current state of the issue. Undoubtedly, publications are very useful for studying the issue under consideration, however, these works (in essence, monographs) do not have an educational focus. Meanwhile, in recent years, a number of directive and methodological materials have appeared that regulate the repair of thermal power plants and, in particular, the repair of steam turbines.
The textbook "Repair of steam turbines" offered to the attention of readers is designed for university students studying in the following specialties: 10.14.00 - Gas turbine, steam turbine installations and engines, 10.05.00 - Thermal power plants, 10.10.00 - Nuclear power plants and installations. The manual can also be used in the system of retraining and advanced training of engineering and technical personnel of TPPs and NPPs.
basic principles of turbine repair organization;
reliability indicators, characteristic damage to turbines and the causes of their occurrence;
standard designs and materials of steam turbine parts;
the main operations performed in the repair of all major parts of steam turbines. Issues of alignment, normalization of thermal expansions and vibration state are covered
In conclusion, the directions of development are given, which, according to the authors, will further improve the efficiency of the entire system of repair of steam turbines as a whole.
When working on the manual, the authors widely used modern scientific and technical literature on thermal power plants and nuclear power plants, steam turbines and steam turbine installations, as well as individual materials from turbine plants, JSC "ORGRES" and a number of repair energy enterprises.
The structure and methodology for presenting the material of the textbook were developed by Yu. M. Brodov.
The general version of the textbook was made by Yu. M. Brodov and V. N. Rodin.
Chapter 1 was written by V. N. Rodin, chapters 2 and 12 by B. E. Murmansky, chapters 3; 4; 5; 6; 7; nine; I - A. G. Sharapov and B. E. Murmansky, chapter 8 - L. A. Zhuchenko and A. G. Sharapov, chapter 10 - A. G. Sharapov, chapter 13 - V. V. Lebedev and M. A Kadnikov, chapter 14 - Yu. A. Sakhnin.
Comments on the tutorial would be greatly appreciated and should beedit at the address: 620002, Yekaterinburg, K-2, st. Mira, 19 USTU-UPI, TeploenergeFaculty of Physics, Department "Turbines and Engines". At the same address, this study guide can be ordered.
Chapter 1
REPAIR ORGANIZATION OF TURBINES
1.1. SYSTEM OF MAINTENANCE AND REPAIR OF EQUIPMENT OF POWER PLANTS. BASIC CONCEPTS AND PROVISIONS
Reliable energy supply to consumers is the key to the well-being of any state. This is especially true in our country with harsh climatic conditions, so uninterrupted and reliable performance power plants is the most important task of energy production.
To solve this problem in the power industry, maintenance and repair measures were developed that ensured long-term maintenance of equipment in working condition at the best economic indicators its work and the least possible unscheduled shutdowns for repairs. This system is based on scheduled preventive maintenance (PPR).
PPR systemis a set of measures for planning, preparing, organizing, monitoring and accounting for various types of maintenance and repair of power equipment, carried out according to a pre-planned plan based on a typical scope of repair work, ensuring trouble-free, safe and economical operation of power equipment of enterprises with minimal repair and operating costs. The essence of the PPR system is that after a predetermined operating time, the need for equipment for repair is satisfied by a planned procedure, by carrying out scheduled inspections, tests and repairs, the alternation and frequency of which are determined by the purpose of the equipment, the requirements for its safety and reliability, design features, maintainability and conditions operation.
The PPR system is built in such a way that each previous event is preventive in relation to the next one. According to distinguish between maintenance and repair of equipment.
Maintenance- a set of operations to maintain the operability or serviceability of the product when used for its intended purpose. It provides for the maintenance of equipment: inspections, systematic monitoring of good condition, control of operating modes, compliance with operating rules, manufacturer's instructions and local operating instructions, elimination of minor malfunctions that do not require equipment shutdown, adjustment, and so on. Maintenance of the operating equipment of power plants includes the implementation of a set of measures for inspection, control, lubrication, adjustment, which do not require the withdrawal of equipment for current repairs.
Maintenance (inspections, checks and tests, adjustment, lubrication, flushing, cleaning) makes it possible to increase the warranty time of the equipment until the next current repair, to reduce the volume of current repairs.
Repair- a set of operations to restore the serviceability or performance of products and restore the resources of products or their components. Maintenance, in turn, prevents the need to schedule more frequent overhauls. This organization of scheduled repairs and maintenance operations makes it possible to constantly maintain equipment in a trouble-free condition at minimal cost and without additional unplanned downtime for repairs.
Along with improving the reliability and security of power supply, the most important task of repair maintenance is to improve or, in extreme cases, stabilize the technical and economic performance of equipment. As a rule, this is achieved by stopping the equipment and opening its basic elements (boiler furnaces and convective surfaces heating, flow parts and bearings of turbines).
It should be noted that the problems of reliability and efficiency of operation of TPP equipment are so interrelated that it is difficult to separate them from one another.
For turbine equipment during operation, first of all, the technical and economic condition of the flow path is controlled, including:
salt drift of blades and nozzle devices that cannot be eliminated by washing under load or at idle (silicon, iron, calcium, magnesium oxide, etc.); there are cases when, as a result of skidding, the turbine power for 10 ... 15 days decreased by 25%.
an increase in clearances in the flow path leads to a decrease in efficiency, for example, an increase in the radial clearance in seals from 0.4 to 0.6 mm causes an increase in steam leakage by 50%.
During repairs, an important role is played by pressure testing and elimination of air suction points, as well as the use of various progressive seal designs in rotating air heaters. The repair personnel must monitor, together with the operating personnel, air suction and, if possible, ensure their elimination not only during repairs, but also on operating equipment. Thus, a decrease (deterioration) in vacuum by 1% for a 500 MW power unit leads to fuel overrun by approximately 2 tons of fuel equivalent. t/h, which is 14 thousand tce. tons / year, or in 2001 prices 10 million rubles.
The efficiency of a turbine, boiler, and ancillary equipment is usually determined by rapid tests. The purpose of these tests is not only to assess the quality of repairs, but also to regularly monitor the operation of the equipment during the overhaul period of operation. An analysis of the test results allows one to reasonably judge whether the unit should be stopped (or, if possible, individual elements of the installation should be turned off). When making decisions, the possible costs of shutdown and subsequent start-up, restoration work, possible undersupply of electricity and heat are compared with losses caused by the operation of equipment with reduced efficiency. Express tests also determine the time during which equipment is allowed to operate with reduced efficiency.
In general, maintenance and repair of equipment involves the implementation of a set of works aimed at ensuring the good condition of the equipment, its reliable and economical operation, carried out at regular intervals and in sequence.
Repair cycle- the smallest repeated intervals of time or operating time of the product, during which, in a certain sequence, in accordance with the requirements of regulatory and technical documentation, all established species repair (running time of power equipment, expressed in years of calendar time between two scheduled overhauls, and for newly commissioned equipment - running time from commissioning to the first scheduled overhaul).
The structure of the repair cycle determines the sequence of various types of repairs and maintenance of equipment within one repair cycle.
All repairs of equipment are divided (classified) into several types depending on the degree of preparedness, the amount of work performed and the method of repair.
Unscheduled repairs- repairs carried out without prior appointment. Unscheduled repairs are performed when equipment defects occur, leading to its failure.
Scheduled repairs- repair, which is carried out in accordance with the requirements of regulatory and technical documentation (NTD). Scheduled repair of equipment is based on the study and analysis of the resource of parts and assemblies with the establishment of technically and economically sound standards.
The planned repair of a steam turbine is divided into three main types: capital, medium and current.
Overhaul- repairs performed to restore serviceability and restore a full or close to full life of equipment with the replacement or restoration of any of its parts, including basic ones.
Overhaul is the most voluminous and complex type of repair, when it is performed, all bearings, all cylinders are opened, the shaft line and the flow part of the turbine are disassembled. If a major overhaul is carried out in accordance with a standard technological process, then it is called typical overhaul. If a major overhaul is carried out by means different from the standard ones, then such a repair refers to specialized repair with the name of a derived type from a typical overhaul.
If a major typical or major specialized repair is performed on a steam turbine that has been in operation for more than 50 thousand hours, then such repairs are divided into three categories of complexity; the most complex repairs are in the third category. The categorization of repairs is usually applied to turbines of power units with a capacity of 150 to 800 MW.
The categorization of repairs according to the degree of complexity is aimed at compensating for labor and financial costs due to the wear and tear of turbine parts and the formation of new defects in them along with those that appear during each repair.
Maintenance- repair performed to ensure or restore the operability of equipment, and consisting in the replacement and (or) restoration separate parts.
The current repair of a steam turbine is the least voluminous; during its execution, bearings can be opened or one or two control valves can be disassembled, and an automatic shutter valve can be opened. For block turbines, current repairs are divided into two categories of complexity: the first and second (the most complex repairs have the second category).
Medium repair- repairs carried out in the amount established in the NTD, to restore serviceability and partial restoration of the equipment resource with the replacement or restoration of individual components and monitoring their technical condition.
The average repair of a steam turbine differs from the overhaul and current one in that its nomenclature partially includes the volumes of both overhaul and current repairs. When performing a medium repair, one of the turbine cylinders can be opened and the shafting of the turbine unit can be partially disassembled, the stop valve can also be opened and a partial repair of the control valves and units of the flow path of the opened cylinder can be performed.
All types of repairs are united by the following features: cyclicality, duration, volume, financial costs.
cyclicality- this is the frequency of one or another type of repair on a scale of years, for example, between the next and previous major repairs, no more than 5 ... should not exceed 2 years. An increase in the cycle time between repairs is desirable, but in some cases this leads to a significant increase in the number of defects.
Duration repair for each main type based on standard works is directive and approved by the "Rules for the organization of maintenance and repair of equipment, buildings and structures of power plants and networks" . The duration of the repair is defined as a value on the scale of calendar days, for example, for steam turbines, depending on the capacity, a typical overhaul is from 35 to 90 days, the average is from 18 to 36 days, and the current one is from 8 to 12 days.
Important issues are the duration of the repair and its financing. The duration of the turbine repair is a serious problem, especially when the expected scope of work is not confirmed by the state of the turbine or when additional work occurs, the duration of which can reach 30 ... 50% of the directive.
Volume of work are also defined as a typical set of technological operations, the total duration of which corresponds to the directive duration of the type of repair; in the Rules, this is called "nomenclature and scope of work for the overhaul (or other type) of turbine repair" and then there is a listing of the names of work and the elements to which they are directed.
Derived names of repairs from all main types of repairs differ in the volume and duration of the work. The most unpredictable in terms of volume and timing are emergency repairs; they are characterized by such factors as the suddenness of an emergency shutdown, the unpreparedness for repair of material, technical and labor resources, the ambiguity of the reasons for the failure and the volume of defects that caused the shutdown of the turbine unit.
When performing repair work can be used various methods, including :
aggregate repair method- an impersonal repair method, in which faulty units are replaced with new or pre-repaired ones;
factory repair method- repair of transportable equipment or its individual components at repair enterprises based on the use of advanced technologies and developed specialization.
Repair of equipment is carried out in accordance with the requirements of regulatory, technical and technological documentation, which include industry standards, technical specifications for repairs, repair manuals, PTE, guidelines, norms, rules, instructions, performance characteristics, repair drawings, etc. .
At the current stage of development of the electric power industry, characterized by a low rate of renewal of fixed production assets, the priority of equipment repair and the need to develop a new approach to financing repairs and technical re-equipment are increasing.
The reduction in the use of the installed capacity of power plants has led to additional wear and tear of equipment and an increase in the share of the repair component in the cost of generated energy. The problem of maintaining the efficiency of energy supply has increased, in the solution of which the leading role belongs to the repair industry.
The existing power repair production, previously based on preventive maintenance with the regulation of repair cycles, has ceased to meet economic interests. The previously operating PPR system was formed to carry out repairs in the conditions of a minimum reserve of energy capacities. Currently, there has been a decrease in the annual operating time of equipment and an increase in the duration of its downtime.
In order to reform the current system of maintenance and repair, it was proposed to change the system of preventive maintenance and switch to a repair cycle with an assigned overhaul life by type of equipment. The new maintenance and repair system (STOIR) allows you to increase the calendar duration of the overhaul campaign and reduce the average annual repair costs. Under the new system assigned overhaul life between overhauls is taken equal to the base value of the total operating time for the repair cycle in the base period and is a standard.
Taking into account the current regulations at power plants, standards for overhaul resources for the main equipment of power plants have been developed. The change in the PPR system is due to the changed operating conditions.
Both the one and the other equipment maintenance system provide for three types of repairs: major, medium and current. These three types of repairs constitute a unified maintenance system aimed at maintaining the equipment in working condition, ensuring its reliability and the required efficiency. The duration of equipment downtime in all types of repairs is strictly regulated. The issue of increasing the downtime of equipment in repair, if it is necessary to perform above-standard work, is considered each time individually.
In many countries, the system of repair of power equipment "on condition", which allows to significantly reduce the cost of repair maintenance, is used. But this system involves the use of methods and hardware that allow with the necessary frequency (and continuously for a number of parameters) to monitor the current technical condition of the equipment.
Various organizations in the USSR, and later in Russia, developed systems for monitoring and diagnosing the state of individual turbine units, attempts were made to create on powerful turbine units complex systems diagnostics. These works require significant financial costs, but, according to the experience of operating similar systems abroad, they quickly pay off.
1.2. VOLUME AND SEQUENCE OF OPERATIONS DURING REPAIR
The administrative documents define the nomenclature and standard scopes of repair work for each type of the main equipment of the TPP.
So, for example, when performing a major overhaul of a turbine, the following is carried out:
Inspection and inspection of cylinder bodies, nozzles, diaphragms and diaphragm cages, seal cages, end seal housings, end and diaphragm seals, devices for heating flanges and casing studs, rotor blades and bandages, impeller disks, shaft necks, support and thrust bearings , bearing housings, oil seals, rotor coupling halves, etc.
Elimination of detected defects.
Repair of cylinder body parts, including metal inspection of cylinder bodies, replacement of diaphragms if necessary, scraping of planes of horizontal connectors of cylinder bodies and diaphragms, ensuring alignment of parts of the flow part and end seals and ensuring gaps in the flow part in accordance with the standards.
Repair of the rotors, including checking the deflection of the rotors, if necessary, replacing the wire bands or the stage as a whole, grinding the necks and thrust disks, dynamic balancing of the rotors and correcting the alignment of the rotor on the coupling halves.
Repair of bearings, including, if necessary, replacement of thrust bearing pads, replacement or refilling of thrust bearing shells, replacement of sealing ridges of oil seals, scraping of the plane of the horizontal separation of cylinder bodies.
Repair of couplings, including checking and correcting fracture and displacement of axes when mating coupling halves (pendulum and knee), scraping the ends of coupling halves, machining holes for connecting bolts.
Testing and characterization of the control system (ACS), fault detection and repair of control and protection units, adjustment of the ACS before starting the turbine are carried out. Also, fault detection and elimination of defects in the oil system are carried out: cleaning of oil tanks, filters and oil pipelines, oil coolers, as well as checking the density of the oil system.
1.3. FEATURES OF ORGANIZATION OF EQUIPMENT REPAIR AT TPP AND POWER REPAIR ENTERPRISE
Repair of TPP equipment is carried out by TPP specialists (economic method), specialized energy repair units of the energy pool (system economic method) or third-party specialized energy repair enterprises (ERP). In table. As an example, Table 1.1 shows data for 2000 (from the official website of RAO "UES of Russia") on the distribution of repair work between its own repair personnel and contractors for the energy systems of the Ural region.
Table 1.1
The ratio of repair work performed by own and involved repair personnel in some power systems of the Urals
The director, Chief Engineer, heads of workshops and departments, senior foremen, just foremen, engineers of departments and laboratories. On fig. 1.1, one of the possible repair management schemes is shown only in the scope of repair of individual parts of the main equipment, in contrast to the actual scheme, which also includes the organization of equipment operation. All heads of the main divisions, as a rule, have two deputies: one deputy for operation, the other for repair. The director decides on financial issues of repairs, and the chief engineer on technical ones, receiving information from his deputy for repairs and from the heads of workshops.
For thermal power plants whose main task is to produce energy, it is not economically feasible to carry out maintenance and repair of equipment in full on their own. It is most advisable to involve specialized organizations (sections) for this.
Repair maintenance of the equipment of boiler and turbine shops at TPPs is carried out, as a rule, by the centralized repair shop (CCR), which is a specialized unit capable of repairing equipment in the required amount. The CCR has material and technical means, including: warehouses of property and spare parts, office rooms equipped with communications equipment, workshops, a mechanical repair section (RMU), lifting mechanisms, and welding equipment. CCR can partially or completely repair boilers, pumps, elements of the regeneration system and vacuum system, chemical plant equipment, fittings, pipelines, electric drives, elements gas facilities, machine tools, vehicles. The CCR is also involved in the repair of the network water recirculation system, maintenance of repair of coastal pumping stations.
From the one shown in Fig. 1.2 of the approximate scheme of the organization of the CCR, it can be seen that the repair in the engine room is also divided into separate operations, the implementation of which is carried out by specialized units, groups and brigades: "flowers" - they repair the cylinders and the flow path of the turbine, "controllers" - repair the components of the automatic control system and steam distribution; oil facilities repair specialists repair the oil tank and oil pipelines, filters, oil coolers and oil pumps, "generator workers" repair the generator and exciter.
Repair of power equipment is a whole complex of parallellazy and intersecting works, therefore, during its repair, all divisions, links,groups, teams interact with each other. For a clear implementation of the complex operationwalkie-talkies, organizing the interaction of individual repair units, determiningterms of financing and delivery of spare parts before the start of repairs is being developedschedule for its implementation. A network model of the equipment repair schedule is usually developed (Fig. 1.3). This model determines the sequence of work and possible dates start and end of major repair operations. For convenient use in repair, the network model is performed on a daily scale (the principles of building network models are presented in Section 1.5).
Own maintenance personnel of power plants performs maintenance of equipment, part of the scope of repair work during scheduled repairs, emergency recovery work; specialized repair companies, as a rule, are involved in major and medium repairs of equipment, as well as its modernization.
More than 30 ERPs have been created in Russia, the largest of which are Lenenergoremont, Mos-energoremont, Rostovenergoremont, Sibenergoremont, Uralenergoremont and others. The organizational structure of an energy repair enterprise (using the structure of Uralenergoremont as an example, Fig. 1.4) consists of management and workshops, the name of the workshops indicates the type of their activity.
Rice. 1.2. Approximate scheme of the organization of the CCR
For example, the boiler shop repairs boilers, the electrical shop repairs transformers and batteries, the control and automation shop repairs the SART of steam turbines and steam boiler automation systems, the generator shop repairs electric generators and engines, and the turbine shop repairs the flow path of turbines. A modern ERP, as a rule, has its own production base, equipped with mechanical equipment, cranes, and vehicles.
Turbine repair shop usually ranks second in the ERP in terms of the number of employees after the boiler shop; it also consists of a management group and production sites. In the workshop management group there is a chief and his two deputies, one of whom organizes repairs, and the other deals with preparations for repairs. The turbine repair workshop (turbine workshop) has a number of production sites. Usually these sections are based on TPPs within their service region. The section of the turbine repair shop at a thermal power plant, as a rule, consists of a work manager, a group of foremen subordinate to him and senior foremen, as well as a team of workers (locksmiths, welders, turners). When the overhaul of the turbine begins at the TPP, the head of the turbine repair shop sends a group of specialists there to carry out repair work, which must work together with the personnel of the site available at the TPP. In this case, as a rule, a specialist from the traveling engineering and technical staff is appointed as the repair manager.
When a major overhaul of equipment is carried out at a TPP where there is no ERP production site, traveling (line) personnel of the workshop with a manager are sent there. If there are not enough traveling personnel to perform a specific amount of repairs, workers from other permanent production sites based at other TPPs (as a rule, from their own region) are involved in it.
The management of the TPP and the ERP will agree on all issues of repair, including the appointment of an equipment repair manager (usually he is appointed from among the specialists of the general contracting (general) organization, i.e. ERP).
As a rule, an experienced specialist in the position of senior foreman or lead engineer is appointed as the repair manager. Repair operations managers are also appointed only experienced professionals in a position not lower than the master. If young specialists are involved in the repair, then by order of the head of the workshop they are appointed as assistants to specialist mentors, that is, foremen and senior foremen who manage the key repair operations.
As a rule, the TPP’s own personnel and several contractors are involved in the overhaul of equipment, therefore, a repair manager is appointed from the TPP, who decides on the interaction of all contractors; under his leadership, daily ongoing meetings are held, and once a week meetings are held with the chief engineer of the TPP (the person who is personally responsible for the condition of the equipment in accordance with the current RD). If failures occur in the repair, which lead to a disruption in the normal course of work, the heads of workshops and chief engineers of contracting organizations take part in the meetings.
1.4. PREPARATION FOR EQUIPMENT REPAIR
At TPPs, the preparation for repairs is carried out by specialists from the Department for the preparation and implementation of repairs (OPPR) and the centralized repair shop. Their tasks include: planning repairs, collecting and analyzing information on new developments in measures to improve the reliability and efficiency of equipment, timely distribution of orders for spare parts and materials, organizing the delivery and storage of spare parts and materials, preparing documentation for repairs, providing training and retraining of specialists, conducting inspections to assess the operation of equipment and ensure safety during repairs.
During periods between overhauls, the CCR is engaged in routine maintenance of equipment, training of its specialists, replenishment of its resources with materials and tools, repairs of machine tools, lifting mechanisms and other repair equipment.
The equipment repair schedule is coordinated with higher organizations (energy system management, dispatch control).
One of the most important tasks in preparing for repairs of TPP equipment is the preparation and implementation of a comprehensive schedule for the preparation of repairs. A comprehensive schedule for preparing for repairs should be developed for a period of at least 5 years. A comprehensive plan usually includes the following sections: development of design documentation, manufacture and purchase of repair tools, training of specialists, construction volumes, repair of equipment, repair of machine park, repair of vehicles, social and domestic issues.
The long-term comprehensive plan for the preparation for repairs is a document that defines the main direction of activity of the TPP repair departments to improve repair services and prepare for repairs. When preparing the plan, the availability of funds at the TPP necessary to carry out repairs is determined, as well as the need to purchase tools, technologies, materials, and more.
A distinction should be made between means of repair and resources of repair.
Repair Tools- this is a set of products, devices and various equipment, as well as various materials with which repairs are carried out; These include:
standard tools manufactured by machine-building enterprises or firms and purchased by repair enterprises in the amount of annual need (keys, drills, milling cutters, hammers, sledgehammers, etc.);
standard pneumatic and power tools manufactured by factories such as "Pnevmostroymash" and "Elektromash";
standard metalworking machines manufactured by machine-building plants in Russia and foreign countries;
fixtures manufactured by machine-building plants under contracts with repair enterprises;
fixtures designed and manufactured by the repair enterprises themselves under contracts between themselves;
fixtures manufactured by factories and supplied to installation sites along with the main equipment.
Under repair resources should be understood as a set of means that determine "how to make repairs"; these include information:
about the design features of the equipment;
repair technologies;
designs and technical capabilities repair equipment;
in the order of development and execution of financial and technical documents;
rules for organizing repairs at thermal power plants and the customer's internal regulations;
safety regulations;
rules for drawing up timesheets and documents for the write-off of products and materials;
features of work with repair personnel in the preparation and conduct of a repair company.
1.5. MAIN PROVISIONS OF REPAIR WORKS PLANNING
During the repair of TPP equipment, the following main features are characteristic:
The dynamism of the repair work, which is manifested in the need for a high pace, the involvement of a significant number of repair personnel on a wide front in parallel ongoing work, the continuous flow of information about newly identified equipment defects and changes in volume (repair work is inherent in the probabilistic nature of the planned scope of work and the strict certainty of the timing set of works).
Numerous technological links and dependencies between various works for the repair of individual units within the repaired equipment, as well as between the nodes of each unit.
The non-standard nature of many repair processes (each repair differs from the previous one in its scope and conditions of work).
Various restrictions in material and human resources. During the period of work, it is quite often necessary to divert personnel and material resources for the urgent needs of the existing production.
Tight deadlines for repairs.
Process Modeling overhaul allows you to simulate the process of repairing equipment, obtain and analyze the relevant indicators and, on this basis, make decisions aimed at optimizing the volume and timing of work.
Linear model- this is a sequential (and parallel, if the works are independent) set of all works, which allows you to determine the duration of the entire complex of works by counting horizontally, and the calendar need for personnel, equipment and materials by counting vertically. The linear graph obtained as a whole (Fig. 1.5) is a graphical model of the problem being solved and belongs to the group of analog models. The linear modeling method is used in the repair of relatively simple equipment or in the production of small amounts of work (for example, current repairs) on complex equipment.
Linear models are not able to reflect the main properties of the modeled repair system, since they lack connections that determine the dependence of one work on another. In the event of any change in the situation during the course of work, the linear model ceases to reflect the real course of events and it is impossible to make significant changes to it. In this case, the linear model must be rebuilt. Linear models cannot be used as a management tool in the production of complex work packages.
Rice. 1.5. Line Chart Example
network model- this is a special type of operating model that provides, with any required accuracy of detail, a display of the composition and interrelationships of the entire complex of works in time. The network model lends itself to mathematical analysis, allows you to determine a real schedule, solve problems of rational use of resources, evaluate the effectiveness of managers' decisions even before they are transferred for execution, evaluate the actual state of the work package, predict the future state, and timely detect bottlenecks.
The components of the network model are a network graph, which is a graphical display technological process repairs, and information about the progress of repairs.
The main elements of the network diagram are the work (segments) and events (circles).
There are three types of work:
actual work- work that requires time and resources (labor, material, energy and others);
expectation- a process that requires only time;
fictitious job- dependence that does not require time and resources; a fictitious job is used to depict objectively existing technological dependencies between jobs.
Dummy work is shown as a dotted arrow.
Event in the network model is the result of performing specific work. For example, if we consider "scaffolding" as a work, then the result of this work will be the event "scaffolding completed". An event can be simple or complex, depending on the results of one, two, or more of incoming works, and can also not only reflect the facts of the completion of the works included in it, but also determine the possibility of starting one or more outgoing works.
An event, unlike work, has no duration; its characteristic is the time of completion.
By location and roles in the network event model are divided into the following:
origin event, the commission of which means the possibility of starting the implementation of a complex of works; it has none incoming work;
end event, the commission of which means the end of the implementation of the complex of works; it has none outgoing work;
intermediate event the completion of which means the end of all the work included in it and the possibility of starting the execution of all the outgoing work.
Network models that have one final event are called single-purpose.
The main feature of the complex of repair works is the presence of a work execution system. In this regard, there is a concept precedence and immediate precedence. If the jobs are not linked by a precedence condition, then they are independent (parallel), so when depicting the repair process in network models, only works that are interconnected by a precedence condition can be displayed sequentially (in a chain).
The primary information about the repair work of the network model is the amount of work expressed in natural units. According to the volume of work, on the basis of the norms, the labor intensity of work in man-hours (man-hours) can be determined, and knowing the optimal composition of the link, it is possible to determine the duration of the work.
Basic rules for building a network diagram
The schedule should clearly show the technological sequence of work.
Examples of displaying such a sequence are given below.
Example 2. After completing the work "laying the high pressure hose into the cylinder" and "laying the RSD into the cylinder", you can start the work "aligning the rotors" - this dependence is shown below:
Example 1 After "stopping and cooling down the turbine", you can start "disassembling the insulation" of the cylinders - this dependence is depicted as follows:
Example 3 To start the work "opening the HPC cover" it is necessary to complete the work "disassembly of the fasteners of the horizontal HPC connector" and "disassembly of the HPD-RSD coupling", and to "check the alignment of HPS-RSD" it is enough to complete the work "Disassembly of the HPS-RSD coupling" - this dependence is shown below:
There should be no cycles in the network schedules for the repair of power equipment, for the cycles testify to the distortion of the relationship between the works, since each of these works comes before itself. An example of such a loop is shown below:
Network diagrams should not contain errors like:
deadlocks of the first kind- the presence of events that are not initial and do not have incoming works:
deadlocks of the second kind- the presence of events that are not final and do not have outgoing work:
All network events must be numbered. The following requirements apply to event numbering:
The numbering must be done sequentially, by numbers of the natural series, starting from one;
The end event number of each job must be greater than the start event number; fulfillment of this requirement is achieved by the fact that the event is assigned a number only after the initial events of all the works included in it are numbered; 
In a network diagram, each event can only be displayed once. Each number can only be assigned to one specific event. Likewise, each job in a network diagram can only be shown once, and each code can only be assigned to one job. If, for technological reasons, two or more jobs have common start and end events, then in order to exclude the same designation of jobs, an additional event and a dummy job are introduced:
Building network repair models is a rather laborious task, therefore, in recent years, a number of works have been carried out to create computer programs designed to build network graphs.
1.6. MAIN DOCUMENTS USED IN THE PROCESS OF PREPARATION AND REPAIR OF EQUIPMENT
When preparing and carrying out the repair of power equipment, a large number of different documents are used, including: administrative, financial, economic, design, technological, repair, safety documents and others.
Before starting the repair, it is necessary to prepare the relevant administrative and financial documents: orders, contracts, acts on the readiness of equipment for repair, a statement of equipment defects, a statement of the scope of work, estimates for the production of work, certificates of inspection of lifting mechanisms.
In the event that a contractor is involved in the repair, it prepares a contract for the repair and an estimate of the cost of the repair work. The drafted contract determines the status of the contractor, the cost of repairs, responsibilities parties regarding the order the content of seconded personnel and the procedure for mutual settlements. The compiled estimate lists all works related to the repair, their names, quantity, prices, indicates all the coefficients and additions related to the price rate for the period of conclusion of the repair agreement. To estimate the cost of work, as a rule, price lists and reference books, time standards, statements of the amount of work, tariff guides. For certain types of work, a special cost estimate is drawn up; in the case of determining the cost of work on the calculation, reference books of time standards for these types of work are used.
After the contract and the estimate are signed by the customer and the executor, all subsequent documents that determine the financial support for the repair, including (enlarged):
statements for the purchase of tools;
statements for the purchase of materials and spare parts;
statements for the issuance of overalls, soap, gloves;
statements for the issuance of travel allowance (daily allowance, hotel payment, transport payment, etc.);
waybills for transportation of means of repair;
power of attorney for material values;
payment requirements.
Technical conditions for repairs- a regulatory and technical document containing technical requirements, indicators and standards that a particular product must satisfy after a major overhaul.
Overhaul Guide- a regulatory and technical document containing instructions on the organization and technology of repair, technical requirements, indicators and standards that a particular product must satisfy after a major overhaul.
Repair drawings- drawings intended for the repair of parts, assembly units, assembly and control of the repaired product, the manufacture of additional parts and parts with repair dimensions.
Measurement map- a technological control document designed to record the results of measuring controlled parameters with the indication of the signatures of the operation performer, the work manager and the controlling person.
In addition, the archive stores equipment drawings, a set of documents for the technological process of equipment repair, technological instructions for individual special repair operations.
At the TPP, the archive should also store documentation of previously completed equipment repairs. These documents are completed according to the station numbers of the equipment; they are stored in the repair preparation department, partly with the head of the turbine shop, and also with the head of the CCR. The collection and storage of these documents allows you to constantly accumulate information about repairs, which serves as a sort of "medical history" of the equipment.
Before starting the repair of equipment in the ERP shop, a list of employees and persons responsible for the performance of work is developed; an order is issued and approved on the appointment of a repair manager and a list of employees indicating their positions and qualifications.
The appointed repair manager draws up a list of documents required for work. It must contain: financial forms (estimates, acts of form No. 2, additional agreements, time sheets), work time forms, line chart forms, granary books for journaling (technical and shift tasks), lists of persons responsible for orders -tolerances, and forms for the write-off of materials and tools.
During the repair, it is necessary to document the condition of the main equipment and its parts, draw up protocols on the control of the metal of the equipment and spare parts, review the repair schedule if it is necessary to clarify the condition of the equipment, draw up technical solutions for repairs with the elimination of equipment defects by non-standard methods.
The head of the repair in the process of its implementation develops and draws up the following main documents:
an act on the identified defects during the inspection of equipment elements during disassembly (second assessment of the condition of the equipment);
an act to justify a change in the repair deadline, depending on the identified defects;
minutes of meetings on the most important problems of repair, for example: shoveling steps, remounting supports, replacing the rotor, etc.;
updated work schedule due to changes in the scope of work;
financial documents: an additional agreement to the contract and an additional estimate, current acts of acceptance of work performed;
requests for new spare parts and assemblies for the customer: rotor blades, disks, clips, diaphragms, etc.;
acts of node acceptance of equipment from repair;
technical solutions for non-standard work using non-standard technology;
In addition, the manager organizes the maintenance of journals: the issuance of tasks, technical records, safety briefings at the workplace, the availability of tools, fixtures and materials, time sheets, sheets for the issuance of mittens, napkins and others.
Upon completion of the repair, also under the guidance of ERP and TPP specialists, the following are developed and formalized:
acceptance certificates from the repair of the main components of the equipment;
protocols for closing cylinders;
protocol for handing over the oil tank for cleanliness;
equipment assembly forms;
protocols for the density of the vacuum system;
protocols of hydraulic tests;
act of pressure testing of the generator and its seals;
list of main parameters and technical condition;
an act for balancing the shafting of a turbine unit;
linear schedules for the completion of work;
collection of forms and reporting documents;
acts on the write-off of spare parts and materials used for repairs.
1.7. MAIN METAL CONTROL METHODS USED IN TURBINE REPAIRS
In the process of repair of turbine units, a large amount of work is carried out to control the metal, while using a combination of various physical methods of non-destructive testing. Their application does not create any residual changes in the product under test. These methods detect cracks, internal cavities, zones of friability, lack of penetration in welds, and similar violations of the continuity and uniformity of materials. The following methods are most common: visual inspection, ultrasonic flaw detection, magnetic particle flaw detection, eddy current testing.
Method of magnetic-powder flaw detection is based on the fact that particles of a ferromagnetic substance, placed on a magnetized surface, accumulate in the zone of inhomogeneity of the medium.
When conducting flaw detection, the surface of a magnetized product is sprinkled with dry ferromagnetic powder (fine iron or steel filings) or poured with a liquid in which fine ferromagnetic powder is in suspension ("magnetic suspension"); at the same time, in those places where cracks reach the surface of the product (although they are invisible due to their small opening) or come close enough to it, the powder accumulates especially intensively, forming easily noticeable rollers corresponding to the shape of the crack.
As applied to parts made of ferromagnetic materials, the method is highly sensitive and makes it possible to detect various defects on the surface of the part.
Method of ultrasonic flaw detection is based on the ability of the energy of ultrasonic vibrations to propagate with small losses in a homogeneous elastic medium and be reflected from discontinuities in this medium.
There are two main methods of ultrasonic testing - the through sounding method and the reflection method. When carrying out flaw detection, an ultrasonic beam is introduced into the sample and the indicator measures the intensity of vibrations that have passed through the sample or reflected from inhomogeneities located inside the sample. The defect is determined either by a decrease in the energy transmitted through the sample, or by the energy reflected from the defect.
The benefits of ultrasonic testing include:
high sensitivity, allowing to detect small defects;
large penetrating power, allowing you to control large-sized products;
the possibility of determining the coordinates and dimensions of the defect.
Eddy current control method (eddy current method) is based on the fact that eddy currents are induced in a test sample placed in an alternating magnetic field.
When testing metal, an alternating magnetic field is created using electromagnetic coils various shapes(in the form of a probe, in the form of a fork, and others). In the absence of the test object, the empty test coil has a characteristic impedance. If the test object is placed in the electromagnetic field of the coil, then it will change under the influence of the eddy current field. If there are inhomogeneities in the sample material, this will affect the change magnetic field coils. This method can determine the presence of cracks, their depth and size.
When repairing turbines, in addition to the methods described above, in some cases X-ray flaw detection, luminescent flaw detection and other methods are also used.
1.8. TOOL USED IN REPAIR WORK
To perform equipment repairs, a large number of metalwork and measuring tools are used, as well as special devices. Availability and quality necessary tool determines the productivity of labor during repairs. Lack of tools causes frequent downtime.
A set of metalwork and universal tools, which is necessary for the repair of turbines, includes:
cutting tool- cutters, drills, taps, dies, reamers, countersinks, files, trihedral, semicircular and flat scrapers, hacksaws and so on.;
impact cutting- chisels, kreytsmessel, center punches and others;
abrasive- grinding wheels, skins;
mounting- screwdrivers, wrenches, socket, cap and sliding keys, wrenches, wire cutters, pliers, steel, lead and copper sledgehammers, metalwork hammers, lead hammers, copper punches, barbs, scribers, steel brushes, metalwork vise, clamps.
When repairing a turbine, work is performed that requires measurements with high accuracy (up to 0.01 mm). Such accuracy is necessary when determining the degree of wear of parts, when measuring radial and end clearances using centering devices, checking clearances in keyed joints, as well as when assembling a turbine and its components.
For measuring linear dimensions or gaps lamellar and wedge probes, thread gauges, templates, gauges, test prisms, calipers, micrometers are used. Micrometers are also used to measure the outer dimensions of parts.
To measure the internal dimensions of parts or distances between planes, accurately measuring the diameters of bores in turbine cylinders, and also use a micrometer inside gauge to determine the dimensions of the keyways.
When checking the flatness of surfaces calibration plates are used different sizes, such as 300x300 and 500x500.
For measuring slopes when installing foundation frames, aligning cylinders and bearing housings in the longitudinal and transverse directions, as well as for measuring slopes on the necks of the rotors, use the Geological Exploration level or electronic levels.
To measure elevations of parts use a hydrostatic level with micrometer heads.
For measuring load values dynamometers are used on the supports of bearing housings and turbine cylinders.
For measuring beats shaft, thrust disk, end and radial surfaces of couplings, dial gauges are used. In addition, it is convenient to measure the linear movements of parts with them: the run-up of the rotor in the thrust bearing, the stroke of the control spools, and so on.
To mechanize the production of labor-intensive work, a universal and specialized tool with pneumatic and electric drives is used:
pneumatic wrenches for loosening and bolting cylinders, bearing caps;
devices with an electric drive for rotating the rotors at low speeds, used when grinding the rotor necks, turning the bandages of the blades after shoveling, turning the ridges of the labyrinth seals, and so on;
electric grinders for cutting bandage wire when re-blading and drilling blade rivets in discs;
electrically driven mechanical reamers and special self-tightening reamers for reaming holes for blade rivets;
portable radial drilling machines for drilling and ribbed holes;
manual portable grinders with flexible rollers for driving steel cutters or abrasive wheels for filing planar surfaces;
pneumatic grinders, electric scrapers and manual scrapers with removable plates for scraping horizontal cylinder connectors, grinding disks and diaphragms.
For carrying out a number of works during the repair, an electric welding machine and a gas-cutting unit are used.
Flamethrowers are used to heat the parts during the operation of their attachment and removal.
When performing work, production tools and technological equipment are used. The set of tools of production necessary for the implementation of the technological process is called technological equipment.
Technological equipment- means of technological equipment, supplementing technological equipment to perform a certain part of the technological process. An example of technological equipment are: cutting tools, fixtures, calibers and more.
1.9. SELF-CHECK QUESTIONS
What is the purpose of organizing a system for maintenance and repair of TPP equipment?
What is a PPR system?
Define the terms "maintenance" and "repair".
List the main indicators of operational control over the technical and economic condition of the turbine flow path.
What is Express Testing? How are they carried out?
Define the terms "repair cycle" and "repair cycle structure".
What is the fundamental difference between unscheduled and scheduled turbine repairs?
What are the main differences in the types of repairs between capital, medium and current.
What and how are the volume and duration of repairs determined?
What repair methods do you know?
Who are the leaders and responsible persons in the repair of turbines at TPPs?
Who at the TPP is preparing for repairs?
What is the purpose of modeling the repair process? What is a linear model of the repair process?
What is a network model? Explain the term "network diagram as an integral part of the network model".
List the main elements and basic rules for building a repair network schedule.
List the main documents that must be completed before the repair begins.
What documents and by whom are issued upon completion of the repair?
List and classification of tools used in the repair of turbines. What is technological equipment?
The operating parameters of the steam turbine control system must comply with the state standards of Russia and the technical conditions for the supply of turbines.
The degree of uneven regulation of steam pressure in controlled extractions and back pressure must meet the requirements of the consumer, agreed with the turbine manufacturer, and prevent the operation of safety valves (devices).
All checks and tests of the turbine regulation and protection system against overspeed must be carried out in accordance with the instructions of the turbine manufacturers and the current guidelines.
The automatic safety device should operate when the turbine rotor speed increases by 10 - 12% above the nominal value or up to the value specified by the manufacturer.
When the automatic safety device is triggered, the following must be closed:
stop, regulating (stop-regulating) valves of live steam and reheat steam;
stop (cut-off), control and check valves, as well as control diaphragms and steam extraction dampers;
shut-off valves on steam pipelines for communication with third-party steam sources.
The turbine protection system against increasing the rotor speed (including all its elements) must be tested by increasing the speed above the nominal in the following cases:
a) after installation of the turbine;
b) after a major overhaul;
c) before testing the control system by load shedding with the generator disconnected from the network;
d) at start-up after disassembly of the automatic safety device;
e) during start-up after a long (more than 3 months) idle time of the turbine if it is not possible to check the operation of the strikers of the automatic safety device and all protection circuits (with an impact on the executive bodies) without increasing the speed above the nominal one;
f) at start-up after the turbine has been idle for more than 1 month. if it is not possible to check the operation of the strikers of the automatic safety device and all protection circuits (with an impact on the executive bodies) without increasing the speed above the nominal value;
g) at start-up after dismantling the control system or its individual components;
h) during scheduled tests (at least once every 4 months).
In cases "g" and "h" it is allowed to test the protection without increasing the speed above the nominal one (in the range specified by the turbine manufacturer), but with a mandatory check of the operation of all protection circuits.
Testing the protection of the turbine by increasing the speed of rotation should be carried out under the guidance of the foreman or his deputy.
The tightness of the live steam stop and control valves shall be checked by a separate test for each group.
The density criterion is the turbine rotor speed, which is set after the check valves are completely closed at full (nominal) or partial steam pressure in front of these valves. The permissible value of the speed is determined by the manufacturer's instructions or current guidelines, and for turbines, the criteria, the verification of which is not specified in the manufacturer's instructions or current guidelines, should not be higher than 50% of the nominal at nominal parameters before the checked valves and the nominal pressure of the exhaust gas. pair.
With the simultaneous closing of all stop and control valves and the nominal parameters of live steam and backpressure (vacuum), the passage of steam through them should not cause rotation of the turbine rotor.
Checking the tightness of the valves should be carried out after the installation of the turbine, before testing the safety switch by increasing the speed, before shutting down the turbine for a major overhaul, when starting after it, but at least once a year. If during the operation of the turbine signs of a decrease in the density of valves are detected, an extraordinary check of their density should be carried out.
Stop and control valves of live steam, stop (cut-off) and control valves (diaphragms) of steam extractions, cut-off valves on steam pipelines for communication with third-party steam sources should be displaced: at full speed - before starting the turbine and in cases stipulated by the manufacturer's instructions; for part of the stroke - daily during the operation of the turbine.
When pacing the valves at full speed, the smoothness of their stroke and landing should be checked.
The tightness of the check valves of controlled extractions and the operation of the safety valves of these extractions must be checked at least once a year and before testing the turbine for load shedding.
Check valves of controlled heating steam extractions that are not connected with the extractions of other turbines, ROU and other sources of steam may not be tested for density, unless there are special instructions from the manufacturer.
The landing of check valves of all extractions must be checked before each start-up and when the turbine is stopped, and during normal operation periodically according to a schedule determined by the technical manager of the power plant, but at least once every 4 months.
If the check valve fails, the operation of the turbine with the corresponding steam extraction is not allowed.
Checking the closing time of the shut-off (protective, shut-off) valves, as well as taking the characteristics of the control system on a stopped turbine and when it is idling, should be carried out:
after installation of the turbine;
immediately before and after the overhaul of the turbine or the repair of the main components of the control or steam distribution system.
Tests of the turbine control system by instantaneous load shedding corresponding to the maximum steam flow must be carried out: 
upon acceptance of turbines into operation after installation;
after reconstruction, which changes the dynamic characteristic of the turbine unit or the static and dynamic characteristics of the control system.
If deviations in the actual characteristics of control and protection from the standard values are detected, the valve closing time is extended beyond that specified by the manufacturer or in local regulations, or the deterioration of their tightness, the causes of these deviations must be determined and eliminated.
The operation of turbines with the power limiter put into operation is allowed as a temporary measure only under the conditions of the mechanical condition of the turbine plant with the permission of the technical manager of the power plant. In this case, the turbine load must be lower than the limiter setting by at least 5%.
Shut-off valves installed on the lines of the lubrication system, regulation and seals of the generator, the erroneous switching of which can lead to a shutdown or damage to the equipment, must be sealed in the working position.
Before starting the turbine after a medium or major overhaul, the serviceability and readiness to turn on the main and auxiliary equipment, instrumentation, remote and automatic control devices, technological protection devices, interlocks, information and operational communications should be checked. Any faults identified must be corrected.
Before starting the turbine from a cold state (after it has been in standby for more than 3 days), the following must be checked: serviceability and readiness to turn on the equipment and instrumentation, as well as the operability of remote and automatic control devices, technological protection devices, interlocks, information and operational communications; passing technological protection commands to all actuating devices; serviceability and readiness to turn on those facilities and equipment on which repairs were carried out during the downtime. Faults identified in this case must be eliminated before start-up.
The start-up of the turbine should be supervised by the shift supervisor of the shop or a senior driver, and after a major or medium repair, the head of the shop or his deputy.
Turbine start is not allowed in the following cases:
deviations of indicators of thermal and mechanical conditions of the turbine from the permissible values regulated by the turbine manufacturer;
malfunction of at least one of the protections acting to stop the turbine;
the presence of defects in the control and steam distribution system, which can lead to turbine acceleration;
malfunctions of one of the oil pumps for lubrication, regulation, generator seals or automatic switching devices (ATS);
oil quality deviations from the standards for operating oils or oil temperature drops below the limit set by the manufacturer;
deviations in the quality of live steam in terms of chemical composition from the norms.
Without turning on the barring device, steam supply to the turbine seals, hot water and steam discharge into the condenser, steam supply to warm the turbine are not allowed. The conditions for supplying steam to a turbine that does not have a barring device are determined by local instructions. 
The discharge of the working medium from the boiler or steam pipelines into the condenser and the supply of steam to the turbine for its start-up must be carried out at the steam pressure in the condenser specified in the instructions or other documents of the turbine manufacturers, but not higher than 0.6 (60 kPa).
When operating turbine units, the root-mean-square values of vibration velocity of bearing supports should not exceed 4.5 mm·s -1 .
If the standard value of vibration is exceeded, measures must be taken to reduce it within a period of not more than 30 days.
If the vibration exceeds 7.1 mm s -1, it is not allowed to operate the turbine units for more than 7 days, and if the vibration is 11.2 mm s -1, the turbine must be turned off by the protection action or manually.
The turbine should be immediately stopped if, under steady state conditions, there is a simultaneous sudden change in the rotational frequency vibration of two supports of one rotor, or adjacent supports, or two vibration components of one support by 1 mm s -1 or more from any initial level.
The turbine must be unloaded and stopped if within 13 days there will be a smooth increase in any component of the vibration of one of the bearing supports by 2 mm·s -1 .
Operation of the turbine unit with low-frequency vibration is unacceptable. When a low-frequency vibration exceeding 1 mm·s -1 occurs, measures must be taken to eliminate it.
Temporarily, before equipping with the necessary equipment, it is allowed to control vibration by the range of vibration displacement. At the same time, long-term operation is allowed with an oscillation span of up to 30 microns at a rotation frequency of 3000 and up to 50 microns at a rotation frequency of 1500; a change in vibration by 12 mm s -1 is equivalent to a change in the amplitude of oscillations by 1020 microns at a rotation frequency of 3000 and 2040 microns at a rotation frequency of 1500.
Vibration of turbine units with a capacity of 50 MW or more should be measured and recorded using stationary equipment for continuous vibration monitoring of bearing supports that meets state standards.
To monitor the state of the turbine flow path and its salt entrainment, at least once a month, the values of steam pressure in the control stages of the turbine should be checked at close to nominal steam flow rates through the controlled compartments.
The increase in pressure in the control stages compared to the nominal at a given steam flow rate should be no more than 10%. In this case, the pressure should not exceed the limit values set by the manufacturer.
When the limiting pressure values are reached in the control stages due to salt drift, the flow path of the turbine must be flushed or cleaned. The method of flushing or cleaning should be selected based on the composition and nature of the deposits and local conditions.
During operation, the efficiency of the turbine plant must be constantly monitored by systematic analysis of indicators characterizing the operation of the equipment.
To identify the reasons for the decrease in the efficiency of the turbine plant, to evaluate the effectiveness of repairs, operational (express) tests of the equipment should be carried out.
The turbine must be immediately stopped (switched off) by the personnel in the event of a failure in the operation of the protections or in their absence in the following cases: 
increasing the rotor speed in excess of the setpoint for the operation of the automatic safety device;
impermissible axial shift of the rotor;
unacceptable change in the position of the rotors relative to the cylinders;
unacceptable decrease in oil pressure (fire-resistant liquid) in the lubrication system;
unacceptable lowering of the oil level in the oil tank;
unacceptable increase in oil temperature at the drain from any bearing, bearings of the generator shaft seals, any block of the thrust bearing of the turbine unit;
ignition of oil and hydrogen on the turbine unit;
unacceptable decrease in the oil-hydrogen pressure drop in the turbogenerator shaft seal system;
inadmissible lowering of the oil level in the damper tank of the oil supply system for the turbine generator shaft seals;
shutdown of all oil pumps of the hydrogen cooling system of the turbogenerator (for non-injector schemes of oil supply to seals);
shutdown of the turbogenerator due to internal damage;
unacceptable increase in pressure in the condenser;
unacceptable pressure drop in the last stage of backpressure turbines;
sudden increase in vibration of the turbine unit;
the appearance of metallic sounds and unusual noises inside the turbine or turbogenerator;
appearance of sparks or smoke from the bearings and end seals of the turbine or turbogenerator;
unacceptable decrease in the temperature of live steam or steam after reheating;
the occurrence of hydraulic shocks in the live steam pipelines, reheating or in the turbine;
detection of a rupture or a through crack in non-switchable sections of oil pipelines and pipelines of the steam-water path, steam distribution units;
stopping the flow of cooling water through the stator of the turbogenerator;
unacceptable reduction in cooling water consumption for gas coolers;
power failure on remote and automatic control or on all instrumentation;
the occurrence of an all-round fire on the contact rings of the rotor of the turbogenerator, auxiliary generator or exciter collector;
failure of the software and hardware complex of the automated process control system, leading to the impossibility of controlling or monitoring all the equipment of the turbine plant.
The need to break the vacuum when turning off the turbine must be determined by local regulations in accordance with the manufacturer's instructions. 
The local regulations must give clear indications of unacceptable deviations in the values of the controlled values for the unit.
The turbine must be unloaded and stopped within the period determined by the technical manager of the power plant (with notification of the power system dispatcher), in the following cases:
jamming of stop valves of live steam or steam after reheating;
jamming of control valves or breakage of their stems; sticking of rotary diaphragms or check valves of selections;
malfunctions in the control system;
violation of the normal operation of auxiliary equipment, circuits and communications of the installation, if the elimination of the causes of the violation is impossible without stopping the turbine;
increase in the vibration of supports above 7.1 mm·s -1 ;
identifying a malfunction of technological protections that affect equipment shutdown;
detection of oil leaks from bearings, pipelines and fittings that create a fire hazard;
detection of fistulas in sections of pipelines of the steam-water path that are not disconnected for repair;
deviations in the quality of fresh steam in terms of chemical composition from the norms;
detection of an unacceptable hydrogen concentration in the bearing housings, current conductors, oil tank, as well as an excess of hydrogen leakage from the turbogenerator housing.
For each turbine, the duration of the rotor run-out must be determined during shutdown with normal pressure of the exhaust steam and during shutdown with a breakdown of the vacuum. When changing this duration, the reasons for the deviation must be identified and eliminated. The duration of the run-down must be controlled during all shutdowns of the turbine set.
When the turbine is taken into reserve for a period of 7 days or more, measures must be taken to preserve the equipment of the turbine plant.
Thermal testing of steam turbines should be carried out.
REPAIR OF STEAM TURBINES
BRIEF DESCRIPTION OF THE COURSE: The course of the program provides for advanced training of working personnel involved in the technical operation of the main and auxiliary equipment of turbine units.
The course of study is calculated for vocational school repairmen of 3,4,5,6 categories according to ETKS, as well as for management staff (shift supervisors, vocational school repair foremen).
Course duration learning 40 hours
GOALS: To increase the level of theoretical knowledge and practical skills of students.
FORMS OF TRAINING: Lectures, active participation of students in the learning process, debates, solving situational problems.
PARTICIPANTS:. vocational school repairmen of 3,4,5,6 categories according to ETKS, as well as management staff (shift supervisors, vocational school repair foremen).
SUMMARIZING: At the end of the course, students are surveyed and tested.
Lesson topic | Lesson objective | Area of study | learning techniques | Means of education | Continue value, in minutes |
|
Psychological testing for the level of logical and mathematical thinking | Determine the level of logical and mathematical thinking of each student | cognitive | Psychological tests | Handouts, test forms. | ||
REPAIR OF CYLINDER BODIES | TYPICAL DESIGNS AND BASIC MATERIALS: (Types of cylinders, Applied materials, Mounting units). Typical cylinder defects and their causes. Cylinder opening. MAIN OPERATIONS PERFORMED DURING REPAIR OF CYLINDERS: (Inspection, Metal control, Checking the warping of cylinders, determining corrections for centering the flow path, Determining the magnitude of vertical displacements of the flow path parts when tightening the body flanges, Determining and correcting the reaction of the cylinder supports Eliminating defects). CONTROL ASSEMBLY CLOSE ASSEMBLY AND SEALING OF FLANGED CONNECTIONS OF CONNECTED PIPING | Cognitive | Lecture, debate | Handout | ||
REPAIR OF DIAPHRAGM AND CLAMPS | STANDARD DESIGNS AND BASIC MATERIALS. CHARACTERISTIC DEFECTS OF DIAPHRAGM AND CAGES AND THE REASONS FOR THEIR APPEARANCE. MAIN OPERATIONS PERFORMED DURING REPAIR OF DIAPHRAGM AND CLAMPS: (Disassembly and revision, elimination of defects, Assembly and alignment ). | Cognitive | Handout | |||
SEAL REPAIR | TYPICAL DESIGNS AND BASIC MATERIALS CHARACTERISTIC SEALING DEFECTS AND REASONS FOR THEIR APPEARANCE. MAIN OPERATIONS PERFORMED WHEN REPAIRING SEALS: (Inspection, Checking and adjusting radial clearances, Fitting the linear size of the ring of seal segments, Replacing the antennae of the seals installed in the rotor, Adjusting axial clearances, Restoring clearances in shroud seals) | Cognitive | Handout | |||
REPAIR OF BEARINGS | REPAIR OF SUPPORT BEARINGS: Typical designs and basic materials of thrust bearings) Typical defects of thrust bearings and their causes. The main operations performed during the repair of thrust bearings: (Opening of bearing housings, their revision and repair, Revision of liners, Checking tightness and clearances). Movement of bearings when centering rotors Closing of bearing housings. | Cognitive | Handout | |||
REPAIR OF BEARINGS | REPAIR OF THRUST BEARINGS. Typical designs and basic materials of thrust bearings. Characteristic defects of the thrust part of bearings and their causes. Revision and repair. Control assembly of the support-thrust bearing. CHECKING THE ROTOR AXIS RUN. REFILLING OF THE BABBIT SHELLS OF THE SUPPORT BEARINGS AND THE SHOE OF THE THORST BEARINGS. SPRAYING THE BORINGS OF THE INSERTS. Oil Seal Repair | Cognitive | Lecture, debate | Handout | ||
REPAIR OF ROTORS | TYPICAL DESIGNS AND BASIC MATERIALS CHARACTERISTIC DEFECTS OF ROTORS AND REASONS FOR THEIR APPEARANCE. DISASSEMBLY, CHECK OF BATTLE AND REMOVAL OF ROTORS. MAIN OPERATIONS TO BE PERFORMED WHEN REPAIRING ROTORS: ( revision, Metal control, Elimination of defects). LAYING THE ROTORS INTO THE CYLINDER. | Cognitive | Lecture, debate | Handout | ||
REPAIR OF WORKING BLADES. | TYPICAL DESIGNS AND MAIN MATERIALS OF WORKING BLADES. CHARACTERISTIC DAMAGES OF WORKING BLADES AND REASONS FOR THEIR APPEARANCE. THE MAIN OPERATIONS CARRIED OUT DURING REPAIR OF WORKING BLADES: (Inspection, Metal control, Repair and restoration, Reblading of the impeller, Installation of connections). | Cognitive | Lecture, debate | Handout | ||
REPAIR OF COUPLINGS OF ROTORS | TYPICAL DESIGNS AND MAIN MATERIALS OF COUPLINGS. CHARACTERISTIC DEFECTS OF COUPLINGS AND THE REASONS FOR THEIR APPEARANCE. MAIN OPERATIONS TO BE CARRIED OUT DURING REPAIR OF COUPLINGS: (Disassembly and revision, Metal control, Features of removal and fitting of half-couplings, Elimination of defects, Features of repair of spring couplings). ASSEMBLY OF THE CLUTCH AFTER REPAIR. "PENDULUM" CHECK OF ROTORS. | Cognitive | Lecture, debate | Handout | ||
TURBINE ALIGNMENT | Centering tasks. Carrying out measurements of centering on the coupling halves. Determining the position of the rotor relative to the turbine stator. Calculation of the alignment of a pair of rotors. Features of alignment of two rotors with three thrust bearings. Methods for calculating the alignment of the turbine shafting. | cognitive, | Lecture, exchange of experience | Handout | ||
NORMALIZATION OF THERMAL EXPANSIONS OF TURBINES | DEVICE AND OPERATION OF THE THERMAL EXPANSION SYSTEM. MAIN CAUSES OF DISTURBANCE OF THE NORMAL OPERATION OF THE THERMAL EXPANSION SYSTEM. METHODS FOR NORMALIZING THERMAL EXPANSIONS. THE MAIN OPERATIONS FOR THE NORMALIZATION OF THERMAL EXPANSIONS CARRIED OUT DURING TURBINE REPAIR. | cognitive, | Lecture, exchange of experience | Handout | ||
NORMALIZATION OF THE VIBRATION STATE OF THE TURBO UNIT | MAIN CAUSES OF VIBRATION. VIBRATION AS ONE OF THE CRITERIA FOR ASSESSING THE STATE AND QUALITY OF TURBINE REPAIR. THE MAIN DEFECTS AFFECTING THE CHANGE OF THE VIBRATION STATE OF THE TURBINE AND THEIR SIGNS. METHODS FOR NORMALIZATION OF TURBO UNIT VIBRATION PARAMETERS. | Cognitive | Lecture, exchange of experience | Handout | ||
REPAIR AND ADJUSTMENT OF AUTOMATIC REGULATION AND STEAM DISTRIBUTION SYSTEMS | What documents and in what period should be drawn up and approved for the repair of the ATS and steam distribution before the start of the repair. What work is performed during the repair of ATS and in preparation for it. ATS repair documentation. General requirements for ATS. Removal of characteristics of steam distribution. Removing the characteristics of ATS. | Cognitive | Lecture, exchange of experience | Handout | ||
Repair of the cam distribution mechanism: (Main defects of the cam distribution mechanisms) Repair of control valves: (Inspection of the stem and valve, Inspection of the bearings of the lever and rollers). Steam distribution materials. | Handout | Lecture, exchange of experience | Handout | |||
REPAIR OF ELEMENTS OF THE STEAM DISTRIBUTION SYSTEM | SERVO MOTORS. General requirements for servomotors. The most common defects in servomotors with one-way fluid supply. The main defects of servomotors with two-way fluid supply. | Handout | Lecture, exchange of experience | Handout | ||
TESTING | ||||||
APPENDICES TO THE PROGRAM:
1. Application. Presentation material used in training.
2. Application. Tutorial.