Fuel economy. The main purpose of the fuel oil economy

Scheme of fuel oil economy. Fuel oil can be the main fuel, reserve (for example, in winter time), emergency, kindling, when the main one is solid fuel burned in a pulverized state.

Rice. 5.6. Scheme of fuel oil facilities with ground fuel oil storage:
1 - railway tank car; 2 - overpass; 3 - portable drain tray; 4- drain chute; 5- outlet pipe; 6 - receiving container; 7- fuel oil storage; 8, 11 - fine filters; 9, 12 - pumps; 10 - filter coarse cleaning; 13 - heater; 14 - boiler burners; 15 - recirculation line

Fuel oil is delivered to the consumer by rail, oil tankers, pipelines (if oil refineries are located at short distances). The fuel oil facilities for the delivery of fuel oil by rail consists of the following structures and devices: a drain rack with an intermediate tank; oil storage facilities; oil pumping station; systems of fuel oil pipelines between fuel oil tanks, fuel oil pumping and boiler plants, devices for fuel oil heating; installations for receiving, storing and introducing liquid additives into fuel oil.
The scheme of fuel oil economy with ground oil storage is shown in fig. 5.6. From the railway tanks 1, located at the drain on the overpass 2, the fuel oil through the portable drain tray 3 enters the drain chute 4 and then through the discharge pipe 5 into the receiving tank 6. From it, the fuel oil is supplied through the fuel oil pipelines to the coarse filter 10 and pumps 9 through 8 fine filters are pumped into the fuel oil storage tank 7. From the fuel oil storage tank through fine filters 11 and heaters 13, fuel oil is supplied to the burners of 14 boiler units by pumps 12. Part of the heated fuel oil is sent through the recirculation line 15 to the fuel oil storage to heat up the fuel oil located there. Fuel oil recirculation is designed to prevent solidification of fuel oil in pipelines when its consumption decreases or stops.
When draining from a railway tank, fuel oil moves by gravity along open trays (chutes) into receiving tanks. Steam lines are laid along the bottom of the trays. Fuel oil is drained from the tanks through the lower drain device into the interrail troughs. Fuel oil from the receiving tanks is pumped by submersible oil pumps to the main storage tanks. The heating of fuel oil in the receiving and main tanks up to 70 °C is usually carried out by surface-type tubular heaters heated by steam. There is no steam in hot water boilers, so fuel oil is heated hot water with temperatures up to 150 °C.
To reduce the risk of bottom sediments and contamination of heating surfaces when long-term storage liquid additives such as VNIINP-102 and VNIINP-103 are added to the fuel oil.

Oil storage facilities. The stock of fuel oil is contained in tanks - oil storage tanks, which, as a rule, are at least two. The total capacity of the tanks is selected depending on the performance of the boiler house, distance and method of delivery (railway, pipeline, etc.). Apply a normal range of fuel oil storage facilities with a capacity of 100; 200; 500; 1000; 2000; 3000; 5000; 10,000 and 20,000 m3. Fuel oil storages are carried out on ground, semi-underground (buried) and underground. Reservoirs are basic, consumable and reserve. All of them must have the safety of fuel storage in terms of fire; complete tightness; incombustibility, durability, corrosion resistance against aggressive ground water; ease of maintenance and cleaning from sludge and sediments; the possibility of installing heating devices inside the tank and other technological equipment.
Fuel oil storage tanks are usually made of reinforced concrete or metal. The latter are used in the regions of the Far North and in seismically hazardous areas. Thermal insulation of metal storages is made of polyurethane sheathed metal sheets.

Pumps for pumping fuel oil. The greatest application for pumping fuel oil are gear and screw pumps. The gear pump diagram is shown in fig. 5.7, a. When the gears 2 rotate in the direction indicated by the arrows in the figure, the liquid enters the depressions formed by the gear teeth and the pump housing 4, and moves from the suction cavity 3 to the discharge cavity 1. For silent and smooth supply of the pumped liquid, the teeth of the gears are often oblique. The performance of gear pumps usually does not exceed 20 m3 / h, and the pressure is 12 MPa (1,200 m of water column).
In screw pumps (Fig. 5.7, b), fuel oil is supplied by squeezing it out with screw-threaded rotors. Screw pumps are silent compared to gear pumps and operate with a large number revolutions. The most common are three-screw pumps with a central driving rotor. When the helical rotors 5 rotate, fuel oil enters the opening cavity of the helical channel from the suction cavity 3. With further rotation of the rotors, this cavity closes and the fuel oil in it is transferred to the injection cavity 1. There the cavity opens, and the fuel oil is squeezed out by the protrusions of the screws of the rotors.


Rice. 5.7. Gear (a) and screw (b) pumps:
1 - injection cavity; 2 - gears; 3 - suction cavity; 4 - body; 5 - screw rotors

Oil heaters. Before combustion, fuel oil must be heated, for which a shell-and-tube heat exchanger designs of Giproneftemash (Fig. 5.8). The apparatus consists of three main parts: a body 6, a tube plate 10 with U-shaped tubes flared in it, and a cover. A flange is welded to the cylindrical body on one side, and an elliptical bottom on the other side. In the center of the body, two 9-segment type supports and branch pipes for supplying and discharging fuel oil moving in the annulus are welded on the outside. The tube plate with U-shaped tubes flared in it is a tube bundle 5, which can be removed from the body when disassembling the apparatus and reinserted after inspection and, if necessary, cleaning. The cover (junction box) consists of a cylindrical part, an elliptical bottom welded on one end and a flange welded on the other end. Branch pipes 2 with flanges are welded to the cylindrical part of the cover for connecting pipelines for supplying and discharging the coolant moving in the tube cavity. The lid also has a baffle J, which provides a two-way flow of coolant through the tubes of the apparatus.


Rice. 5.8. Shell-and-tube heat exchanger with U-shaped tubes designed by Giproneftemash:
1, 7 - bottom; 2 - branch pipes for inlet and outlet of the coolant; 3 - partition; 4 - flange; 5 - tube bundle; b - body; 8 - branch pipes for the supply and removal of fuel oil; 9 - support; 10 - tube board

For heating small quantities liquid fuel heaters have found a fairly wide application of "pipe in pipe" type heaters.
A sectional fuel heater of the PTS type is shown in fig. 5.9. The design of the steam sectional liquid fuel heater is a series of sections connected in series for steam and fuel using connecting tubes of the “Kalach” type with flanges. The heater section consists of three main parts: body, cover 11 and heating tube 7.
The body of the heater is made of two parallel pipes of the same diameter, to the ends of which a flange 9 is welded on one side. rectangular shape, and on the other hand, special pipes for mounting the fuel inlet 6 and outlet 3 valves, as well as flanges to ensure tightness when the fuel passes from one section to another. The housing has a fitting for installation safety device with increasing pressure. Cover 11 of the heater is welded, flanged to the body. The heating tube has a U-shape, equipped with longitudinal ribs 13 welded to the outer surface over the entire length of the straight part of the tube and designed to increase the heat transfer surface from the fuel side. Outside, the heater is closed with insulation 12.
The principle of operation of the heater is as follows. Fuel from the line through stop valve enters the annular space (between the body and the heating tube), washes the outer surface and the fins of the heating tube, heats up and passes through the cover to another section or through the valve to the outlet. Heating steam from the steam pipeline through the steam valve 4 enters heating tube; the heat of the steam is transferred to the fuel through the tube wall and fins, then the steam is condensed and in the form of condensate through valve 5 is removed from the heater to the feed water preparation system.


Rice. 5.9. Sectional fuel heater type PTS:
1 - movable support; 2 - fixed support; 3 - fuel outlet valve; 4 - steam valve; 5 - condensate outlet valve; 6 - fuel inlet valve; 7 - heating tube; 8 - heater housing; 9 - housing flange; 10 - bolt; 11 - cover; 12 - insulation; 13 - ribs of the heating tube;
A and B - fuel inlet and outlet; B - steam inlet; G - condensate outlet

The main purpose of the fuel oil economy of a CHP or boiler house is to ensure uninterrupted supply of heated and filtered fuel oil to the boilers in the required quantity and with the appropriate pressure and viscosity. The required amount of fuel oil is determined by the load of the boilers. The pressure in the fuel oil supply lines and its viscosity are determined by the modes of the nozzles.

The operation of boiler houses on fuel oil is carried out very rarely (during periods of limited consumption gas fuel), so its update is stretched to long time. During long-term storage, fuel oil gradually deteriorates its qualities and creates additional technical difficulties for the operating personnel.

Since fuel oil is quite expensive, large power plants run on gas, and liquid fuel - fuel oil is used as a backup. The operating mode of the fuel oil economy is provided as an emergency kindling, with gas supply limited, during emergency on the gas equipment kindling of boilers is carried out with fuel oil.

The fuel oil facility is intended for the following works:

acceptance of railway tanks with fuel oil;

warming up tank cars;

draining fuel oil from tanks;

fuel oil storage in tanks;

preparation and processing of fuel oil before supplying it to pumps and nozzles;

accounting for consumed fuel oil;

The fuel oil facility can operate in two modes - in cold or hot standby.

cold reserve- this is when the equipment of the fuel oil pumping station is stopped and only, depending on the duration of downtime, the internal circulation circuit is periodically switched on to maintain the temperature in the fuel oil tanks in the range from 300 C to 800 C.

Hot standby- fuel oil pipelines are filled with fuel oil and there is a constant flow of fuel oil heated to T = 750 to 800 C through the main pressure fuel oil pipeline, the oil ring of the boiler room, the recirculation (return) pipeline, depending on the selected scheme.

The choice of a fuel oil supply scheme for a boiler house depends on a number of local conditions: the relief of the territory, the capacity of the tanks, the method of supplying fuel oil from the fuel storage to the boiler nozzles, and others.

When heating fuel oil in an open supply tank, in order to avoid foaming, its temperature should not exceed 90C. The fuel oil supplied to the nozzles is heated in separate heaters. As a rule, it is recommended to supply fuel from storage tanks to nozzles with continuous circulation of fuel oil. At the same time, part of the fuel oil, not less than 50% of the consumption for all working boilers, returns to the tanks and serves to heat the fuel oil in them.

Fuel oil farms are distinguished by the method of fuel delivery.

Classification of fuel oil farms by purpose.

The main fuel oil facilities are built at thermal power plants, for which fuel oil is the main type of fuel burned, and gas is burned as a buffer fuel during its seasonal surpluses.

The reserve is created at thermal power plants, where the main fuel is gas, and fuel oil is burned during its absence (usually in winter).

Emergency fuel oil facilities are provided for at stations for which the main and only type of fuel is gas, and fuel oil is used only in the event of an emergency interruption of its supply.

There is a kindling fuel oil facility at all power plants that use solid fuels with a chamber combustion method. Fuel oil is used to kindle and illuminate the torch in the furnaces of boilers. In the case of installation of oil-fired peak hot water boilers at such power plants, their fuel oil economy is combined with the kindling one. At thermal power plants, three schemes are used for supplying liquid fuel to nozzles:

Dead-end, circulation and combined.

Scheme of fuel oil facilities with ground fuel oil storage:

1-railway tank; 2-trestle; 3-portable drain tray; 4-drain chute; 5-outlet pipe; 6-receiving capacity; 7-oil storage; 8, 11 fine filters; 9, 12-pumps; 10 coarse filter; 13-heater; 14 boiler burners; 15-line recirculation.

From the railway tanks 1, located at the drain on the overpass 2, the fuel oil through the portable drain tray 3 enters the drain chute 4 and then through the discharge pipe 5 into the receiving tank 6. From it, the fuel oil is supplied through the fuel oil pipelines to the coarse filter 10 and pumps 9 through filters 8 are pumped into the oil storage tank 7. From the oil storage tank through fine filters 11 and heaters 13, fuel oil is supplied to the burners of 14 boiler units by pumps 12. Part of the heated fuel oil is sent through the recirculation line /5 to the fuel oil storage to heat up the fuel oil located there. Fuel oil recirculation is designed to prevent solidification of fuel oil in pipelines when its consumption decreases or stops. When draining from a railway tank, fuel oil moves by gravity along open trays (chutes) into receiving tanks. Steam lines are laid along the bottom of the trays. Fuel oil is drained from the tanks through the lower drain device into the interrail troughs. Fuel oil from the receiving tanks is pumped by submersible oil pumps to the main storage tanks. The heating of fuel oil in the receiving and main tanks up to 70°C is usually carried out by surface-type tubular heaters heated by steam. There is no steam in water-heating boiler houses; therefore, fuel oil is heated with hot water with a temperature of up to 150 ° C. To reduce the risk of bottom sediments and contamination of heating surfaces during long-term storage, liquid additives such as VNIINP-102 and VNIINP-103 are added to fuel oil.

Thermal diagram of a boiler room with steel hot water boilers

Thermal diagram of a boiler house with steel steam boilers

Thermal diagrams of boiler plants

On fig. 53 is a schematic thermal diagram of a heating and production boiler house with water tube boilers working on closed system heat supply. The thermal scheme is typical for boiler houses with boilers DKVR, KE, DE and other medium-pressure boilers with pre-boiler water treatment.

Rice. 53. Thermal diagram of a boiler room with steel steam boilers:

1 - boiler; 2 - main steam pipeline; 3 - reducing installation; 4 - steam-water heater; 5 – condensate cooler; 6 - jumper; 7 - network pump; 8 - condensate tank; 9 - condensate pump; 10 - make-up pump; 11 - deaerator; 12 - steam feed pump; 13 - feed pump with electric drive; 14 – vapor cooler; 15 – blowdown water cooler; 16 - HVO; 17 – raw water heater; 18 - purge well; 19 - raw water pump; 20 – continuous purge separator; 21 - economizer; 22, 23, 24 - pressure reducing valve; 25 - steam pipeline for own needs.

Steam from boilers 1 enters the main steam pipeline 2, from where it is sent to production to heat water in network installation(SU).

The CS consists of a steam-water heater, a condensate cooler 5 and a network pump 7 and a reduction unit 3. Water from the heating network with a design temperature of 70 0 C is first heated by condensate in the condensate cooler and then, finally, by steam in the steam-water heater and with design temperature 130-150 0 C enters heating network. The movement of water in the heating network and through the CS heat exchangers is produced by the network pump 7.

The CS receives steam from a reduction unit, which reduces the steam pressure to 0.6-0.7 MPa and maintains it constant when the steam flow rate changes. In order to avoid steam entering the heating network when the heater tubes are depressurized, the steam pressure must be 0.1-0.2 MPa lower than the network water pressure.

Having given up its heat to the network water, the steam in the installation turns into condensate, which has a pressure of 0.6-0.7 MPa and a temperature of 160-165 0 C. To prevent condensate from boiling in deaerator 11, the condensate is cooled in 5 to a temperature of 80-90 0 . To provide reliable operation SU the number of steam-water heaters, condensate coolers and network pumps is accepted at least two for each type of equipment.

Condensate from production is returned to the condensate tank 8, from where it is fed to the deaerator by a condensate pump 9.

Water losses in the boiler house and heating network are replenished with source water using a pump19.

Before entering the boilers raw water softened in chemical water treatment filters 16 (HVO) and released from corrosive gases in nutrient deaerator 11.

To prevent fogging of pipelines and equipment, the source water is heated with steam up to 15-20 0 C in the heat exchanger 17 before the cold water treatment plant.

In the deaerator 11, gases are released from boiling water at a temperature of 102-104 0 C and a pressure of 0.12 MPa. It is worth saying that steam from the auxiliary steam line 25 with a pressure of not more than 0.2 MPa is used to heat water.

Steam boilers are fed with water from a group feeding plant, including centrifugal pumps 13 electric and steam piston pumps 12. Pumps take water from the deaerator and supply it to the boilers through individual water feed economizers 21.

When the power supply to the boiler room is interrupted, water is supplied to the boilers by a steam pump, which is extremely important to prevent the failure of the boilers due to overheating of their heating surfaces (to cool the boilers).

The operation of steam boilers is accompanied by continuous blowing of their upper drums. To reduce heat losses with blowdown water, a blowdown separator 20 and a blowdown water cooler 15 are used. The pressure in the separator is maintained at a level of 0.17-0.2 MPa, which is significantly lower than the pressure in the boiler. For this reason, boiler water boils in the separator and steam is formed at a pressure of 0.17-0.2 MPa and with a temperature of 115-120 0 C. The steam is removed to the deaerator, and the water is cooled to 60-40 0 well 18. Periodic blowdown water also enters here. From the purge well, water is drained into the sewerage system of the facility. The temperature of the drained water is limited by local conditions and, as a rule, should not exceed 60 0 C.

Steel hot water boilers operate on water that has passed cold water treatment and deaeration. Due to the lack of steam in the boiler room, vacuum deaeration is used.

To protect the boilers from low-temperature gas corrosion, a network water recirculation system around the boilers is used, which provides heating of water up to 70 - 100 0 С at the boiler inlet by mixing it into the return network water hot water from boilers.

Rice. 54. Thermal diagram of a boiler room with steel hot water boilers:

1 – boiler; 2 - recirculation pump; 3 - jumper; 4 - supply pipeline; 5 - return pipeline; 7 – raw water pump; 8 - heater; 9 - HVO; 10 - heater; 11 - deaerator; 12 - transfer pump; 13 - storage tank; 14 - make-up pump.

The boilers are connected in parallel to the supply 4 and return 5 mains of the heating network (Fig. 54). Chilled water with a temperature of 70 0 C is taken from the return line by network pumps 6 and pumped through the boilers. Water heated in boilers with a temperature of 150 0 С is supplied to consumers through the supply pipeline. When the temperature of the return network water drops to values ​​at which a low-temperature gas corrosion in the tail heating surfaces of the boilers, part of the hot water is supplied to the inlet to the boilers with the help of a recirculation pump 9.

To control the temperature of the direct network water, bypass line 3 is used, through which the cooled return network water mixed with hot water.

In large boilers, for example, of the PTVM type, each boiler receives water from its mains pump and has individual systems recycling and mixing. In such cases, one backup network pump common to all boilers is additionally installed.

Losses and leaks of water from the heating network are compensated by softened and deaerated water, which is supplied by the make-up pump 14 to the suction manifold of the network pumps.

For the preparation of make-up water, raw water is used, which is supplied to the boiler room by a pump 7. Before the water softening filters 9 and before the deaerator 11, the water is initially heated with hot water from the boilers in heat exchangers 8 and 10. 6 - 9 0 C, which is extremely important for its intensive boiling at a temperature of 70 0 C at a pressure of 0.03 MPa. The vacuum in the deaerator is created by water jet ejectors.

When operating the boiler open system heat supply in thermal scheme tanks are switched on - hot water accumulators and pumps pumping deaerated water into these tanks.

Very often, in boiler houses burning fuel oil, steam is used to heat fuel oil and deaerate water, which is generated in steam boilers installed in boiler rooms. The use of steam makes it possible to increase the reliability of the operation of deaerators and increase the intensity of fuel oil heating compared to hot water used for these purposes.

17. Fuel economy of boiler houses

17.1. Fuel economy of solid fuel boiler houses

Storage and supply of coal to the boiler room. Coal is delivered to the supply warehouse by rail or by car. In the warehouse, coal is stored in stacks, the height of which depends on the grade of coal. For hard coal the height of the stacks is limited to 6-7 meters. Coals prone to spontaneous combustion are stored in stacks no more than 4 m high. Passages for vehicles are left between the stacks. Warehouses are equipped with fire extinguishers to fight fires.

The supply of coal to the boiler room and to the boilers depends on the method of burning coal and is carried out manually (carts, wheelbarrows, trolleys) or using various mechanisms (forklifts, bulldozers, belt conveyors, lifts, etc.).

Boilers with semi-mechanical and mechanical furnaces are equipped with individual bunkers, from which coal is fed to the coal feeders into the furnace. Delivery of coal to the bunkers is carried out in most cases by a bucket elevator (Fig. 55).

Rice. 55. Scheme of fuel supply with a bucket lift:

1 - crusher; 2 - bucket; 3 - vertical guides; 4 - horizontal guides; 5 – bucket tippers; 10 - winch.

Ladle 2 is mounted on a trolley, which moves along rails with the help of a traction rope and an electric winch 10. The ladle is loaded with crushed coal coming from crusher 1, rises to the level of boiler bins and moves along horizontal guides 4 to the corresponding boiler bin. The bucket is unloaded into the bunker by tilting it. The capacity of the bucket is 0.5 - 1.5 m 3, and the capacity of the boiler hopper is designed for a supply of coal for 10 - 18 hours of operation.

Fuel supply systems with belt conveyors are also used.

The fuel oil farm consists of a warehouse and a system for supplying fuel oil to the nozzles. Fuel oil enters the warehouse in road or rail tanks and is drained into a receiving tank 3 (Fig. 57). To heat fuel oil in railway tanks, steam is used, which is directly introduced into the volume of fuel oil through a heating device. The fuel oil heating temperature depends on its brand and is 30-40 0 C. From the receiving tank, fuel oil is pumped into fuel storage tanks 5 equipped with steam heating.

Fig.57. Principal circulation diagram of the fuel oil economy:

1 - railway tank; 2 - drain tray; 3 - receiving container; 4 - transfer pumps; 5 – fuel storage tanks; 6- ventilation pipes reservoirs; 7 - coarse filter; 10 - fuel pumps; 11- bypass line; 12- heater; 13 - fine filter; 14 - pressure line; 15 - return line; 16 - bypass valves; 17 - boiler nozzles; 18 - boilers

Fuel oil is supplied to the nozzles 17 according to the circulation scheme, when more fuel oil is supplied to the boilers than is burned, and the excess fuel oil is returned to the tanks. The constant movement of fuel oil through all fuel oil pipelines eliminates solidification of fuel oil in temporarily non-operating sections of fuel oil pipelines and ensures quick activation of backup boilers. At the same time, a jet of hot fuel oil returning to the tank intensively heats the fuel oil and erodes the bottom sediments in the tank.

On the way to the nozzles, the fuel oil is heated in heater 12 to a temperature that is extremely important for high-quality atomization. Considering the dependence on the brand of fuel oil, this temperature reaches 80 - 120 0 C. To avoid clogging of the nozzles, fuel oil is cleaned of mechanical impurities in coarse filters 7 and fine filters 13. The filters have the same design and differ from each other in the mesh size of the filter mesh.

For pumping fuel oil and its supply to the nozzles, gear, rotary-tooth and rock pumps are used. Pumps together with fuel oil heaters and filters are installed in separate building, called mazutonasosnaya.

Control nutrition

1. Commodity nomenclature and product range.

2. Kіlkіsnі аnd аkіsnі indicators of nomenclature and assortment of products.

3. Assortment concept and її warehousing.

4. Basic procedures for molding assortment.

5. Perevagi і nedolіki standardizatsії and diferentsіacії product.

6. The essence of the commodity policy.

7. Marketing strategies of diversification.

Oil farms are divided into:

1. basic. The main fuel oil economy is intended for the operation of a thermal power plant or a boiler house only on fuel oil, fuel oil and gas or fuel oil as a reserve fuel.

2. kindling. Kindling fuel oil facilities are used for boilers operating on solid fuels(pulverized coal), for kindling boilers and highlighting the torch in the furnace; they apply only to TPPs.

Schemes of fuel oil economy, depending on the fuel pressure in front of the boiler nozzles, are divided into two-stage - with pumps and fuel oil pumping of the first and second rise, and single-stage - with one stage of pumps. AT two-stage schemes pumping fuel oil through the boiler house is carried out by pumps of the second lift. The task of the first lift pumps is to pump fuel from the main tanks through heaters and fine filters to the suction of the second lift pumps, as well as supply fuel through the recirculation line to the main tanks. In single-stage schemes, pumping fuel from the main tanks through fine filters and heaters through the boiler room with recirculation back to the main tanks is carried out by one stage of pumps.

A fuel oil pipeline scheme is also used with a two-stage fuel oil pumping station with a dedicated recirculation circuit with recirculation pumps and pumping fuel oil from the main tanks through the heaters after recirculation pumps back to the main tanks. Single stage circuits are used in industrial boiler houses and thermal power plants with a capacity of less than 250 MW.

Fuel preparation schemes depend on the method of supplying fuel oil, the power of power plants or boilers, and the properties of the fuel.

In the complex of facilities and devices for fuel oil management of the boiler house industrial enterprise includes:

1. receiving and draining devices;

2. oil storage facilities (receiving and main tanks);

3. fuel oil pumping station (with pumps, heaters, filters);

4. steam and oil pipelines;

5. installations for receiving, storing and introducing liquid additives;

6. fire extinguishing system.

The fuel oil facility is intended to perform the following main operations:

1. railway reception. or tank trucks with fuel oil;

2. warming up tank cars;

3. draining fuel oil from tanks;

4. fuel oil storage in tanks;

5. preparation and processing of fuel oil before supplying it to pumps and nozzles;

6. fuel oil supply to nozzles;

7. Accounting for consumed fuel.

Fuel oil economy of heating boiler houses

Fuel oil economy - a set of devices that provide acceptance, storage and supply required amount fuel oil to the boiler room and preparing it for burning in boiler furnaces. Fuel oil can be the main fuel, reserve (for example, in winter), emergency, kindling, when the main one is solid fuel burned in a pulverized state.

The main elements of the fuel oil economy are: a receiving device, fuel oil storage, fuel oil additive tank, supply tank, coarse and fine filters, fuel oil heaters, condensate coolers, pipeline systems (fuel oil pipelines, steam and condensate pipelines, drainage pipeline), pumps for various purposes. Fuel oil is delivered to the consumer by rail, oil tankers, pipelines (if oil refineries are located at short distances). Fuel oil delivered in rail and truck tanks is heated to a temperature of 30-60 ° C, depending on its brand. For this purpose, dry saturated or slightly superheated steam with a pressure of 5-6 kgf / cm 2 is most often used, supplied directly to the tank. It is also possible to use portable coil heaters for this purpose, which eliminates the flooding of fuel oil. The fuel oil drained from the tank must pass through a special filter that prevents mechanical impurities from entering the fuel oil storage. The sites where the drains are located must have hard covers with a drain to divert spilled fuel oil to the local treatment plant. The fuel oil facilities for the delivery of fuel oil by rail consists of the following structures and devices: a drain rack with an intermediate tank; oil storage facilities; oil pumping station; fuel oil pipeline systems between fuel oil tanks, fuel oil pumping and boiler plants, devices for fuel oil heating; installations for receiving, storing and introducing liquid additives into fuel oil. The scheme of the fuel oil economy with a ground fuel oil storage is shown in Figure 1. From the railway tanks 1, which are located at the overpass 2 when draining, fuel oil flows through a portable drain tray 3 into a drain chute 4 and then through a discharge pipe 5 into a receiving tank 6. From it, fuel oil fuel oil pipelines are fed into the coarse filter 10 and pumped through pumps 9 through the filters 8 by the race cleaning is pumped into the fuel oil storage tank 7. From the fuel oil storage tank through fine filters 11 and heaters 13 pumps 12 fuel oil is supplied to the burners of 14 boiler units. Part of the heated fuel oil is sent through the recirculation line 15 to the fuel oil storage to heat up the fuel oil located there. Fuel oil recirculation is designed to prevent solidification of fuel oil in pipelines when its consumption decreases or stops.

Fig.1. Scheme of fuel oil facilities with ground fuel oil storage: 1-railway tank; 2-trestle; 3-portable drain tray; 4-drain chute; 5-outlet pipe; 6-receiving capacity; 7-oil storage; 8, 11 fine filters; 9, 12-pumps; 10 coarse filter; 13-heater; 14 boiler burners; 15-line recirculation.

When draining from a railway tank, fuel oil moves by gravity along open trays (chutes) into receiving tanks. Steam lines are laid along the bottom of the trays. Fuel oil is drained from the tanks through the lower drain device into the interrail troughs. Fuel oil from receiving tanks is pumped by submersible oil pumps to the main storage tanks - oil storage tanks, which, as a rule, are at least two. The total capacity of the tanks is selected depending on the performance of the boiler house, distance and method of delivery (railway, pipeline, etc.). Apply a normal range of fuel oil storage facilities with a capacity of 100; 200; 500; 1000; 2000; 3000; 5000; 10,000 and 20,000 m 3. Fuel oil storage facilities are ground, semi-underground (buried) and underground. Reservoirs are basic, consumable and reserve. All of them must have the safety of fuel storage in terms of fire; complete tightness; incombustibility, durability, corrosion resistance against the impact of aggressive groundwater; ease of maintenance and cleaning from sludge and sediments; the possibility of installing heating devices and other technological equipment inside the tank. Fuel oil storage tanks are usually made of reinforced concrete or metal. The latter are used in the regions of the Far North and in seismically hazardous areas. Thermal insulation of metal storages is made of polyurethane sheathed with metal sheets. Reservoirs and tanks must be vented to the atmosphere and have sumps to collect water.

For pumping fuel oil in heating boilers, gear and screw pumps are most commonly used. When the gears 2 rotate in the direction indicated by the arrows in Figure 2, the liquid enters the depressions formed by the gear teeth and the pump housing 4, and moves from the suction cavity 3 to the discharge cavity 1. For silent and smooth supply of the pumped liquid, the teeth of the gears are often made oblique. The performance of gear pumps usually does not exceed 20 m 3 / h, and the pressure is 12 MPa (1,200 m of water column).

Fig. 2. Gear (a) and screw (b) pumps: 1-injection cavity; 2 gears; 3-suction cavity; 4-body; 5 screw rotors.

In screw pumps, fuel oil is supplied by squeezing it out with screw-threaded rotors. Screw pumps are silent compared to gear pumps and operate at high speeds. The most common are three-screw pumps with a central driving rotor. When the helical rotors 5 rotate, fuel oil enters the opening cavity of the helical channel from the suction cavity 3. With further rotation of the rotors, this cavity closes and the fuel oil in it is transferred to the injection cavity 1. There the cavity opens, and the fuel oil is squeezed out by the protrusions of the screws of the rotors.

To ensure heating of fuel oil in the storage, which is necessary for the normal operation of fuel oil pumps, the following methods are used: installation of immersion-type steam heaters in the lower part of the tank; local mine, section or electric heaters; portable heaters. In addition to heating in storage facilities, fuel oil is heated in fuel oil pipelines and in front of nozzles.

At present, fuel oil heaters are used in boiler houses - surface heat exchangers with countercurrent movement of media, with a tubular heat exchange surface, with compensation for thermal elongation due to non-rigid structures. For example, a shell-and-tube heat exchanger designed by Giproneftemash is used. The apparatus consists of three main parts: a body 6, a tube plate 10 with U-shaped tubes flared in it, and a cover. A flange is welded to the cylindrical body on one side, and an elliptical bottom 1 on the other side. In the center of the fuel oil heater body, two supports 9 of the segment type and branch pipes 8 are welded on the outside for supplying and discharging fuel oil moving in the annulus.

The tube plate in the heater with U-shaped tubes flared in it is a tube bundle 5, which can be removed from the fuel oil heater housing when disassembling the apparatus and reinserted after inspection and, if necessary, cleaning. The cover (junction box) consists of a cylindrical part, an elliptical bottom welded on one end and a flange welded on the other end. Branch pipes 2 with flanges are welded to the cylindrical part of the heater cover for connecting pipelines for supplying and discharging the coolant moving in the tube cavity. The cover is also provided with a partition 3, which provides a two-way flow of the coolant through the tubes of the apparatus.

Fig. 3. Shell-and-tube heat exchanger with U-tubes designed by Giproneftemash: 1.7-bottom; 2 branch pipes for inlet and outlet of the coolant; 3-partition; 4-flange; 5-tube bundle; 6-body; 8 branch pipes for the supply and removal of fuel oil; 9-support; 10-tube board.

For heating small amounts of liquid fuel, heaters of the "pipe in pipe" type are widely used.

Fig. 4. Sectional fuel heater type PTS: 1-support movable; 2-support fixed; 3-valve fuel outlet; 4-steam valve; 5-valve for condensate outlet; b-fuel inlet valve; 7-heating tube; 8-heater housing; 9-body flange; 10-bolt; 11-cover; 12-insulation; 13-ribs of the heating tube; A and B - fuel inlet and outlet; V-inlet steam; G-condensate outlet.

The operating principle of the fuel oil heater is as follows. Fuel from the line through the shut-off valve enters the annular space (between the body and the heating tube), washes the outer surface and the fins of the heating tube, heats up and passes through the cover to another section or through the valve to the outlet. The heating steam from the steam pipeline through the steam valve 4 enters the heating tube; through the wall of the heater tube and the fin, the heat of the steam is transferred to the fuel, then the steam is condensed and in the form of condensate through valve 5 is removed from the heater to the feed water preparation system.

During long-term operation at a number of enterprises, serious shortcomings in the operation of these heaters have been identified, which include:

the impossibility of using these heaters on high-viscosity fuel oils with HC ° >100 with a heating temperature of up to 120-135 °C;

an increased rate of deposits on the inner surface of pipes with a decrease in thermal power (the heat transfer coefficient decreases, according to CKTI estimates, to 70%);

difficulties associated with cleaning the inner surface of pipes from deposits of oxidized products of fuel oil polymerization at steam temperatures on the wall above 120 °C;

relatively low speeds fuel oil movements (0.2-0.5 m/s);

low hydraulic density (both for steam and fuel oil) does not allow reuse of heating steam condensate in technological scheme boiler room, which, after cooling, is discharged through treatment facilities into the sewer;

watering of fuel oil due to the possible ingress of steam or condensate into the fuel in cases of fistulas in pipe system heaters.

To supply fuel oil to boilers, three schemes are used: circulating (when using high-viscosity fuel oil, when the boiler house works constantly on fuel oil and for a short time on gas); dead-end (when burning low-viscosity fuel oils, when the boiler house operates at stable loads exceeding the average); combined (during the operation of the boiler house at variable loads and frequent transitions from gas fuel to fuel oil). Regulation of fuel oil supply (pressure) is carried out using a valve with an impulse according to the performance of the boilers or the steam pressure in the boiler. In the circulation scheme, fuel oil is taken from the lower part of the tank, pumped through a remote heater to the boiler room, and then to the tank. This improves the heating of fuel oil and reduces the deposition of impurities in the tank. Piston and screw pumps are used for pumping fuel oil. Fuel oil pipelines from storages to the boiler house and recirculating fuel oil pipeline are laid in trenches or tunnels together with steam pipelines and covered with general insulation. Steam lines must have reliable condensate drainage. To ensure the fuel oil pressure in front of the nozzle is about 20 kgf / cm 2, special pumps are used (gear, vane, screw, plunger).

Problems of fuel oil preparation for combustion

According to the existing traditional technology for preparation for combustion and transportation, the temperature of fuel oil in tanks is in the range of 80-95 ° C and is maintained by local heating by steam heaters located on the bottom of the fuel oil tank. Then, with the help of recirculation heating by remote heaters, heated fuel oil, with the required viscosity, is fed into the boiler room to the boilers. The remaining fuel oil is fed through the recirculation line back to the fuel oil tanks. The spreading of turbulent submerged jets in the tank and the accompanying eddy currents ensure the mixing of fuel oil in the tanks and uniform temperature distribution in the volume of the tanks. At the same time, due to repeated pumping of fuel oil, a coarse water-fuel mixture (emulsion) is obtained, the quality of which does not meet the requirements for combustion conditions. The low quality of the fuel mixture leads to pulsating combustion of fuel oil in the boiler furnace. On the other hand, the technology used for the preparation of fuel oil stored in tanks with a variable moisture content does not allow to properly ensure the high-quality process of settling and removing water from fuel oil to a moisture content that provides conditions for economical and environmentally friendly operation of boilers. Another problem that significantly affects the economic efficiency of the boiler house is that in existing schemes fuel oil facilities of boiler houses, the spent steam condensate from remote oil heaters and those located in tanks after cooling with water from the city water supply system to the required temperature (40 ° C) is discharged into the industrial rain sewerage system and, after cleaning, into the city sewer. Current cleaning methods Wastewater from petroleum products are expensive and not always effective. This is especially true for the treatment of water heavily polluted with oil products, which may appear during breaks or fistulas in fuel oil heaters. Therefore, the return of oil-contaminated condensate to the feed circuit of steam boilers can lead to their failure to operate. The loss of condensate from the fuel oil heaters leads to the need to supplement the boiler circuit with chemically treated make-up water and additional fuel.

Fuel oil combustion.

Modern methods of industrial combustion of fuel oil in boiler furnaces are based on flare combustion of finely atomized fuel at obligatory condition its preliminary heating and forced spraying with the help of nozzles. For spraying oil on heating boilers most commonly used nozzles with mechanical or steam spray, as well as combined steam-mechanical spray. Mechanical nozzles require high pressure and even under these conditions cannot provide a wide range of load control. Steam spray nozzles require steam flow, which is difficult to achieve in a boiler room with hot water boilers. In recent years, rotary nozzles have appeared on the Russian market, devoid of such disadvantages as design complexity and noise in operation. One of these samples is the nozzles of the company "ZAAKE" (Bremen, Germany). They can burn any liquid fuel oil, including fuel oils of grades 40 and 100, residues of heavy mineral oils, tar, etc. They do not require thorough filtering of the fuel oil. However, all of the above nozzles do not provide flame stability when burning heavily watered fuel oil, the completeness of combustion of coarse fractions that accumulate in bottom sediments during long-term storage of fuel oil. It is not possible to solve these problems by improving the design of the injectors.

A significant disadvantage of operating oil-fired boilers is the contamination of the heating surfaces of the boiler, which causes a deterioration in heat transfer conditions compared to operation on gas. The excess air coefficient is also somewhat higher, which leads to a decrease in the efficiency of the boiler. In boiler houses, where fuel oil is a reserve (emergency) fuel, short-flame burners GMGM are most widely used. Fuel oil is supplied to the spray head, in which are installed: a distribution washer with one row of holes, fuel and steam swirlers, each having three tangential channels. The washer and swirlers are attached with a union nut. The number and diameter of holes in the distribution washer are as follows: in burners GMG-1.5M and GMG-2M-8 with a diameter of 2.5, in burners GMG-4M and GMG-5M - 12 with a diameter of 3 mm. Fuel oil passes through the holes of the washer, enters the swirler chamber through the channels and exits the nozzle, spraying due to centrifugal force. If the required thermal power is within 70-100% of the nominal one, it is possible to work without steam supply, since the mechanical atomization of fuel oil is sufficient. When the heat power is below 70% of the nominal steam is supplied with a pressure of 1.5-2 kgf/cm 2 , which passes through the channels of the steam swirler and participates in the spraying of fuel oil in a swirling flow.

When burning fuel oil, it is necessary to ensure that carbon deposits, resinous and other deposits do not accumulate on the inner surfaces of the nozzles, which worsen the conditions for spraying fuel oil, which causes incomplete combustion. The presence of such deposits can be judged by the appearance of flying drops - “stars” in the furnace. Therefore, the nozzles should be periodically removed from the burners, cleaned of deposits and flushed with solar oil or other light fuel.

Devices and methods for combustion and purification of fuel oil.

Along with organizational and financial reasons for the unsatisfactory state of heat supply systems, there are serious technical reasons. Currently, there is no rational and economically feasible method of high-quality atomization of fuel oil without a spraying agent that meets modern requirements. Regulatory documents regulating the operating modes of thermal power plants were developed decades ago, during a period of relatively cheap fuel. It is likely that the low efficiency of equipment for burning fuel oil (mechanical nozzles) and the energy consumption of the existing technology for burning fuel oil is due to the time of development. At present, according to some reports, branch research institutes are not working in this direction. With a growing shortage of gas, with an increase in the share of fuel oil in the total fuel balance, with an increase in the cost of fuel oil, it is necessary to improve the technology of its combustion and introduce the latest developments. Combustion of fuel oil with the conditional absence of chemical underburning, heat loss due to moisture evaporation of watered fuel, etc. cannot be justified with today's views on energy saving and saving energy resources.

It should be emphasized that the proposed method of fuel oil spraying using cavitation effects is new in the design theory and in the practice of operating TPPs, which, according to some reports, has no analogues in Russia.

The nozzle is designed for high-quality mechanical atomization and combustion of fuel oil in power boilers and settings. The cavitation nozzle is a modern technique that has no analogues in Russia. Distinctive features of this development in comparison with traditional mechanical nozzles are its high efficiency, reliability and ease of maintenance.

High reliability is achieved due to the simplicity of design and the use of materials designed for many years of long-term operation. All maintenance of the nozzle consists only in periodic monitoring of the condition of the parts. Therefore, the use of "Freza" will allow the consumer to simultaneously solve two problems - energy saving and resource.

The principle of operation of the cavitation nozzle.

The nozzle consists of a body, a nozzle, a swirler and a base. The main element of the Frez nozzle is the cavitator, which is a cylindrical body equipped with profiled channels of a special dependence.

When fuel oil is pumped under pressure through the cavitator, a vortex flow is formed in it, in which, under the action of variable pressures in places of fuel inhomogeneities, its breaks occur, which leads to the appearance of tiny bubbles. With the subsequent collapse of the bubbles, sharp pressure jumps occur (the absolute value of the pressure depends on the forces of the surface tension of the liquid and other factors), transverse components of the flow velocity, significant shear stresses of the flow, and a significant local increase in temperature are formed. The continuous formation and collapse of bubbles in the liquid, known as the phenomenon of cavitation, leads to the breaking of oil chains (clusters), the generation of high-frequency oscillations and the instability of the fuel film in front of the nozzle hole. The viscosity of the fuel, due to the breaking of molecular chains and local temperature increases, decreases sharply, and the water contained in the fuel, under the influence of cavitation, partially dissociates into hydrogen (ideal fuel) and oxygen, and partially forms a water-oil emulsion with the fuel. When leaving the nozzle hole, the unstable pulsating gas-oil film instantly falls apart into tiny droplets, inside which there is the smallest particle of water, hydrogen or oxygen. Departing to the area low pressures the gas expands with an explosion, and the water instantly warms up and explodes, which leads to secondary fine crushing of fuel oil to a level of 40 ... 60 microns. The best results are achieved with a dispersion of water particles from 3 to 8 microns. Combustion of fuel oil and hydrogen in the presence of water vapor and active oxygen takes place at extremely low air excesses, without guaranteed underburning of fuel with a combustion efficiency close to one, which leads to fuel savings during combustion. The reduction in the specific consumption of fuel oil can theoretically reach 2.5 ... 3.0% or more, which is hundreds of millions of rubles.

Today, when energy conservation has been introduced into the rank of state policy in all countries of the world, it is necessary to improve the technology of fuel oil combustion at TPPs and boiler houses in every possible way, it is necessary to modernize and improve existing equipment.

Given the compactness, reliability and simplicity of design, cavitation nozzles for mechanical atomization of fuel oil in the burners of boiler units are superior to any other known devices and methods of fuel combustion in terms of the combination of economic and operational parameters.

The use of nozzles "Frez" will allow:

1. Reduce specific consumption fuel oil by 0.5 ... 1.0% and up to 1.5% at low loads in comparison with mechanical nozzles GRFM.

2. Will provide a range of boiler load regulation from 50 to 100%.

3. Reduce excess air in the furnace;

4. Reduce the drift of the heating surfaces of the boiler;

5. Increase efficiency. boiler;

6. To increase the reliability and safety of operation of the boiler unit when burning low-grade fuel oil.

The unit is designed to extract water and mechanical impurities from fuel oils. This process occurs due to the separation of the mixture into 3 phases based on their density difference using different ranges of high speeds and torques. The raw material (contaminated product) is fed through the pipe of the feed mechanism into the rotating part of the screw conveyor, where, under the action of centrifugal force, it is separated into a purified product and sediment. The purified fuel oil is removed from the cylindrical part of the rotor, and the sediment, due to the difference in the speeds of the screw and the rotor, enters the conical part, where it is dehydrated. The dewatered sludge is discharged at the narrow end of the cone through dedicated ports and can be discharged directly into dump trucks or waste containers using a conveyor. The decanter and pump are controlled from the built-in control panel. The centrifuge and pump are explosion-proof. The rest of the water in the purified fuel oil is not more than 1.5%. The rest of mechanical impurities - no more than 1%. The unit is mounted on a solid metal frame.

The technical, technological and organizational-technical measures for the storage and use of the supplied low-grade liquid fuel used today in boiler houses not only do not meet the level of modern requirements for economic and environmental indicators, but also exacerbate them due to:

increased sludge formation with a sharp increase thermal resistance on heating surfaces;

increased coking of fuel oil;

reducing the quality of its spraying;

deterioration in the functioning of burners;

reducing the quality of the fuel combustion process in boiler furnaces;

decrease in reliability, maneuverability of the boiler unit performance and reduction of its overhaul life as a whole;

significant losses of fuel, electricity and water.

Improving the operation of fuel oil facilities in new economic conditions requires an integrated approach to the introduction of new equipment and technologies for storage, preparation for the combustion of fuel oil and its accounting.

This is achieved through the use of such technologies that would provide the required level of heating, filtration, homogenization, pressure and consistency of the quality of fuel oil supplied to combustion, as well as instrumental control of fuel consumption and intake with minimal operating costs. These technologies include:

"cold" storage of fuel oil with the allocation of a heated zone in the volume of the tank along the suction line;

multi-stage preparation of fuel oil to obtain a high-quality fuel (water-fuel) mixture (emulsion) by dispersing the fuel with water (or oily water) and fuel components contained in it;

circulating heating of fuel oil with increased speeds in remote heaters - homogenizers, multiple filtration on filters - heaters;

technology closed circuit fuel oil heating with condensate return to the boiler cycle.

It is necessary to develop a hardware-software complex of measuring devices that allow, taking into account the dynamics of changes in the properties of incoming and consumed fuel oil, to automatically determine its mass.

The energy development strategy of Russia until 2020 provides not only for an increase in oil production, but also a simultaneous increase in the depth of its processing, which will lead to a deterioration in the quality of fuel oil.

federal state autonomous

educational institution

higher professional education

"SIBERIAN FEDERAL UNIVERSITY"

Polytechnical Institute

Department: "T and GGD"

OIL MANAGEMENT OF BOILERS

Student TE 07-05 __________ Golubeva E.A.