CN210714796U - Back-pressure small steam turbine heat-regeneration steam extraction system - Google Patents

Abstract

The utility model relates to a steam turbine technical field especially relates to a little steam turbine of backpressure backheat steam extraction system, including little steam turbine, operating device and at least one first heater, operating device is connected with little steam turbine, and little steam turbine is equipped with at least one extraction opening, and extraction opening and first heater one-to-one just are linked together through the extraction pipeline, are equipped with the extraction valve on the extraction pipeline, and the extraction opening of little steam turbine is equipped with the female pipeline of steam extraction, is equipped with the branch road of steam extraction that leads to the steam extraction user on the female pipeline of steam extraction, is equipped with the extraction valve on the branch road of steam extraction. Through the cooperation regulation of the extraction valve on the extraction pipeline and the exhaust valve on the exhaust branch road, can realize nimble operation, adapt to little steam turbine start-up initial stage and various operating condition, guarantee system safety and stability ground operation, realize the adjustment to little steam turbine backpressure simultaneously, reach the purpose that furthest improves little steam turbine efficiency.

Description

Back-pressure small steam turbine heat-regeneration steam extraction system

Technical Field

The utility model relates to a steam turbine technical field especially relates to a little steam turbine of backpressure backheat steam extraction system.

Background

With the improvement of environmental awareness, thermal power generating sets are continuously developing towards high capacity and high parameter in order to reduce emissions and improve energy utilization efficiency. The higher inlet steam temperature increases the thermal efficiency of the main turbine, but at the same time it also gives rise to a problem in that the recuperative extraction temperature increases significantly. The excessive reheat extraction temperatures greatly increase the construction costs of the entire plant's piping, heaters, boilers, etc. And the regenerative steam extraction temperature exceeds the design requirement, the further improvement of the unit efficiency is not facilitated, and high-quality energy is wasted. According to the latest research at home and abroad, researchers have proposed that the regenerative steam extraction part on a main turbine is provided by a small turbine of a water supply pump, and the efficiency of the whole circulating system can be improved and the investment cost of a power station can be reduced by reasonably arranging the number of regenerative heaters, so that the system is called as a double-machine regenerative system.

A feed water pump turbine is one of main parts of a thermal power station thermodynamic cycle system, and especially plays an important role in a high-parameter and high-capacity ultra-supercritical unit. The thermal power station thermal cycle system mainly comprises a boiler, a steam turbine, a condenser, a regenerative heater, a deaerator, a water feeding pump and the like. Before the condensed water generated by the condenser is heated step by the regenerative system and is sent to the boiler, the water pressure is firstly increased by the water feeding pump, then high-temperature and high-pressure steam is generated in the boiler, and finally the steam enters the steam turbine to do work. The large-scale generating set is usually matched with a small steam turbine to drive a water feeding pump, and steam heat energy is directly used for doing work, so that the plant power consumption rate can be reduced. The working steam source of the small turbine of the feed water pump is usually from the extraction steam of the main turbine part.

According to the conventional million-supercritical unit, regenerative extraction steam is extracted from through flow of a main steam turbine, the superheat degree of the regenerative extraction steam is large, and particularly the regenerative level after reheating is carried out, so that the utilization efficiency of the whole cycle energy level is greatly reduced. After the double-machine regenerative system is adopted, high-temperature regenerative steam extraction is extracted from a small steam turbine for driving a water supply pump, the highest regenerative steam extraction temperature of the whole system does not exceed the high exhaust temperature, and the cycle energy level efficiency is greatly improved. By adopting the ultra-supercritical million units of the double-machine regenerative system, for the design of a steam turbine, when a main steam turbine with high parameters does not need to open a steam extraction opening on a cylinder for supplying a heater, the original steam extraction opening can be cancelled, and the cost of the cylinder can be obviously reduced. Meanwhile, because the extraction temperature is reduced, the pipeline and the regenerative heater do not need to use high-temperature resistant materials, and the manufacturing cost is obviously reduced. In addition, because a large amount of steam extraction from the intermediate pressure cylinder is not needed, the required amount of reheat steam is small, and the construction cost of the boiler is greatly reduced.

The Back pressure Extraction Steam Turbine (BEST Steam Turbine for short) for supplying the Back pressure Extraction Steam has obvious advantages in the aspects of saving energy, reducing cost and the like. However, the operation condition of the variable-speed steam turbine is more complex than that of a conventional steam turbine, the variable-speed steam turbine is a variable-speed steam turbine, and the variable-speed steam turbine has to be operated flexibly and can adapt to some unconventional fault conditions, such as the fault of a certain level of heater, so that the design and development of the variable-speed steam turbine have certain difficulty.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model is to provide a little steam turbine of backpressure backheat steam extraction system that can realize safety, stability, nimble operation to overcome prior art's above-mentioned defect.

In order to solve the technical problem, the utility model discloses a following technical scheme: the utility model provides a little steam turbine of backpressure backheat steam extraction system, includes little steam turbine, operating device and at least one first heater, and operating device is connected with little steam turbine, and little steam turbine is equipped with at least one extraction steam port, and extraction steam port and first heater one-to-one just are linked together through the extraction steam pipe way, are equipped with the extraction steam valve on the extraction steam pipe way, and the extraction steam port of little steam turbine is equipped with the female pipeline of steam extraction, is equipped with the exhaust branch road to the exhaust user on the female pipeline of steam extraction, is equipped with the exhaust steam valve on the exhaust branch road.

Preferably, the steam exhaust branch comprises a regenerative branch, an overflow branch and a steam exhaust bypass, wherein the exhaust pressure of the regenerative branch is sequentially reduced, the regenerative branch leads to the second heater, and the steam exhaust valve comprises a regenerative steam extraction valve arranged on the regenerative branch, an overflow valve arranged on the overflow branch and a steam exhaust bypass valve arranged on the steam exhaust bypass.

Preferably, the overflow branch leads to a third heater or is vented.

Preferably, the heating steam source of the third heater is provided by main turbine extraction steam.

Preferably, the exhaust gas bypass leads to a condenser or is evacuated.

Preferably, a first steam exhaust safety valve is arranged on the steam exhaust main pipeline.

Preferably, a mixing header is arranged on the steam exhaust main pipeline, and the steam exhaust branch is communicated with the mixing header.

Preferably, the mixing header is provided with a steam exhaust safety branch, and the steam exhaust safety branch is provided with a second steam exhaust safety valve.

Preferably, the steam-assisted steam generator further comprises an auxiliary steam source, wherein the auxiliary steam source is communicated with the steam exhaust main pipeline through a steam supplementing pipeline, and a steam supplementing valve is arranged on the steam supplementing pipeline.

Preferably, the steam extraction pipeline is provided with a steam extraction check valve, and the steam exhaust main pipeline is provided with a steam exhaust check valve.

Compared with the prior art, the utility model discloses the progress that has showing:

the utility model discloses a little steam turbine of backpressure backheat steam extraction system, set up the extraction pipeline on little steam turbine, provide backheat steam extraction for first heater, set up the exhaust branch road leading to the steam extraction user on little steam turbine exhaust main pipe, through the extraction valve on the extraction pipeline and the cooperation of the exhaust valve on the exhaust branch road and adjust, can realize nimble operation, adapt to little steam turbine start-up initial stage and various operating condition, guarantee system safety and stability moves, realize the adjustment to little steam turbine backpressure simultaneously, reach the purpose that the at utmost improves little steam turbine efficiency.

Drawings

Fig. 1 is a schematic structural diagram of a backheating steam extraction system of a backpressure small steam turbine according to an embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a first implementation manner of a backheating steam extraction system of a backpressure small steam turbine according to an embodiment of the present invention.

Fig. 3 is a schematic structural diagram of a second embodiment of a backheating steam extraction system of a backpressure small steam turbine according to an embodiment of the present invention.

Fig. 4 is a schematic structural diagram of a third embodiment of a backheating steam extraction system of a backpressure small steam turbine according to an embodiment of the present invention.

Fig. 5 is a schematic structural diagram of a fourth embodiment of a backheating steam extraction system of a backpressure small steam turbine according to an embodiment of the present invention.

Fig. 6 is a schematic structural diagram of a fifth implementation manner of the backheating steam extraction system of the small back pressure turbine according to the embodiment of the present invention.

Wherein the reference numerals are as follows:

1. small steam turbine 2 and working mechanism

3. First heater 4, admission valve

41. Main steam valve 42, steam inlet regulating valve

5. Steam extraction valve 6, steam extraction check valve

7. Steam exhaust check valve 8 and second heater

9. Backheating steam extraction valve 10 and overflow valve

101. Overflow shutoff valve 102, overflow regulating valve

11. Exhaust bypass valve 12, third heater

13. Condenser 14 and regenerative steam extraction check valve

15. Overflow check valve 16 and first steam exhaust safety valve

17. Mixing header 18 and second exhaust safety valve

19. Auxiliary steam source 20 and steam supplementing valve

201. Steam compensation shutoff valve 202 and steam compensation regulating valve

21. Steam supplementing check valve 100 and steam supply pipeline

200. Steam extraction pipeline 300 and steam exhaust main pipeline

400. Regenerative branch 500 and overflow branch

600. Exhaust bypass 700 and exhaust safety branch

800. Steam supplementing pipeline 900 and main turbine steam extraction pipeline

Detailed Description

The following describes the present invention in further detail with reference to the accompanying drawings. These embodiments are provided only for illustrating the present invention and are not intended to limit the present invention.

In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.

As shown in fig. 1 to 6, the present invention provides an embodiment of a regenerative steam extraction system for a back pressure small steam turbine. Referring to fig. 1 and 2, the regenerative steam extraction system of the back pressure small turbine of the present embodiment includes a small turbine 1, a working mechanism 2, and a first heater 3.

Wherein, the steam inlet of the small turbine 1 is communicated with the steam supply pipeline 100, the steam is introduced into the small turbine 1 through the steam supply pipeline 100, and the steam introduced into the small turbine 1 through the steam supply pipeline 100 can be from a boiler or a main turbine. The steam supply pipeline 100 is provided with a steam inlet valve 4 for controlling the on-off and flow of the steam supply pipeline 100. The steam inlet valve 4 may include a main steam valve 41 and a steam inlet regulating valve 42, the opening or closing of the main steam valve 41 controls the on-off of the steam supply pipeline 100, and the opening of the steam inlet regulating valve 42 controls the flow rate of the steam supplied to the steam supply pipeline 100.

The working mechanism 2 is connected with the rotor of the small steam turbine 1, and the steam drives the rotor of the small steam turbine 1 to rotate when flowing in the small steam turbine 1, so that power can be provided for the working mechanism 2, and the working mechanism 2 is driven to operate. The working mechanism 2 is mainly a feed water pump and may also comprise a generator or other driven equipment.

The small steam turbine 1 is provided with a steam extraction opening, the steam extraction opening on the small steam turbine 1 is communicated with the first heater 3 through a steam extraction pipeline 200, the steam extraction of the small steam turbine 1 is introduced into the first heater 3 through the steam extraction pipeline 200 to heat water, heat and working media can be recycled, and the circulation efficiency is improved. Compared with the extraction of the regenerative extraction steam from the through flow of the main steam turbine, the extraction of the regenerative extraction steam from the small steam turbine 1 can avoid the high degree of superheat of the regenerative extraction steam, and the cycle energy level efficiency is greatly improved. The steam extraction pipeline 200 is provided with a steam extraction valve 5, and the on-off of the steam extraction pipeline 200 can be controlled by opening or closing the steam extraction valve 5. The extraction valve 5 may take the form of a shut-off valve, which may be, but is not limited to, a stop valve, gate valve or butterfly valve. Preferably, the extraction conduit 200 may be provided with an extraction check valve 6 for preventing the extraction steam from flowing back along the extraction conduit 200 into the small steam turbine 1.

The number of the first heaters 3 may be plural, the plural first heaters 3 may be arranged step by step in the feed water flow direction and sequentially communicated, and the pressure of each stage of the first heaters 3 increases step by step along the feed water flow direction. Correspondingly, the small steam turbine 1 may be provided with a plurality of steam extraction ports, all the steam extraction ports are sequentially arranged on the small steam turbine 1 at intervals along the steam flow direction, all the steam extraction ports correspond to all the first heaters 3 one to one, and each steam extraction port is communicated with the corresponding first heater 3 through one steam extraction pipeline 200, so that along the steam flow direction in the small steam turbine 1, the pressure at each steam extraction port is gradually reduced, and the steam inlet pressure of each first heater 3 is also gradually reduced. Each steam extraction pipeline 200 is provided with a steam extraction valve 5 and a steam extraction check valve 6. The number of the first heaters 3 is not limited, for example, in the embodiment, three first heaters 3 are provided, three steam extraction ports corresponding to the three first heaters 3 are provided on the small steam turbine 1, and the pressures of the three first heaters 3 are increased step by step along the feed water flow direction.

The steam outlet of the small steam turbine 1 is provided with a steam outlet main pipeline 300, the steam outlet main pipeline 300 is provided with a steam outlet branch leading to a steam outlet user, and the steam outlet branch is provided with a steam outlet valve. The exhaust user refers to the final place where the small turbine 1 exhausts, and may be the atmosphere where the small turbine 1 exhausts directly, or may be a mechanism that can recover the exhaust steam or the exhaust heat of the small turbine 1, such as a condenser that can condense the exhaust steam into condensed water, a heater that can recover the exhaust heat, and the like. The on-off of the steam exhaust branch can be controlled by opening or closing the steam exhaust valve. Preferably, the steam exhaust main pipe 300 may be provided with a steam exhaust check valve 7 for preventing the steam exhaust from flowing back into the small steam turbine 1 from the steam exhaust main pipe 300.

Preferably, the steam exhaust branch may include a regenerative branch 400, an overflow branch 500, and a steam exhaust bypass 600, where the steam exhaust pressure is sequentially reduced, the steam exhaust valve includes a regenerative steam extraction valve 9 disposed on the regenerative branch 400, an overflow valve 10 disposed on the overflow branch 500, and a steam exhaust bypass valve 11 disposed on the steam exhaust bypass 600, and the steam exhaust user may include a second heater 8, a third heater 12, and a condenser 13.

The regenerative branch 400 is connected to the second heater 8, and is configured to introduce a portion of exhaust steam in the exhaust steam main pipe 300 of the small steam turbine 1 into the second heater 8 to heat the feed water, so that the pressure of the second heater 8 is lower than that of the first heater 3, and the second heater 8 can serve as a water supply stage of the first heater 3, that is, the water outlet side of the second heater 8 can be communicated with the water inlet side of the first heater 3. The on-off of the regenerative branch 400 can be controlled by opening or closing the regenerative steam extraction valve 9 on the regenerative branch 400. The regenerative steam extraction valve 9 may take the form of, but is not limited to, a shutoff valve, such as a stop valve, gate valve or butterfly valve. Preferably, a regenerative steam extraction check valve 14 may be disposed on the regenerative branch 400 for backflow of the exhaust steam from the regenerative branch 400 into the exhaust steam main pipe 300.

The overflow branch 500 may lead to the third heater 12, and a part of the exhaust steam in the exhaust steam main pipe 300 of the small steam turbine 1 may be introduced into the third heater 12 through the overflow branch 500 as needed, so as to achieve the purpose of adjusting the pressure of the exhaust steam main pipe 300, that is, the purpose of adjusting the back pressure (exhaust steam pressure) of the small steam turbine 1. The pressure of the third heater 12 is lower than that of the second heater 8, and the third heater 12 can be used as a water supply stage of the second heater 8, that is, the water outlet side of the third heater 12 can be communicated with the water inlet side of the second heater 8. Preferably, the heating steam source of the third heater 12 is provided by the main steam turbine extraction steam, under normal working condition, the overflow branch 500 is disconnected, and the third heater 12 can work normally under the heat provided by the main steam turbine extraction steam; under the fault working condition, the overflow branch 500 can be opened, and the function of adjusting the back pressure of the small steam turbine 1 is achieved. The overflow branch 500 may not be led to the third heater 12, but may be directly evacuated, and the purpose of adjusting the back pressure of the small steam turbine 1 may also be achieved by switching on and off the overflow branch 500. The on-off of the overflow branch 500 can be controlled by opening or closing the overflow valve 10 on the overflow branch 500, and meanwhile, the overflow amount of the overflow branch 500 can be adjusted by adjusting the opening degree of the overflow valve 10, so as to control the back pressure of the small steam turbine 1. Preferably, the overflow valve 10 is a shut-off regulating valve, the overflow valve 10 may be a valve having both shut-off and opening regulating functions, or the overflow valve 10 may be a valve group formed by connecting an overflow shut-off valve 101 and an overflow regulating valve 102 in series, the on-off of the overflow branch 500 is controlled by opening or closing the overflow shut-off valve 101, and the overflow amount of the overflow branch 500 is controlled by regulating the opening of the overflow regulating valve 102. The overflow shutoff valve 101 may be in the form of, but is not limited to, a shut-off valve, a gate valve, or a butterfly valve, for example. Preferably, the overflow branch 500 may be provided with an overflow check valve 15 for preventing the exhaust steam from flowing back from the overflow branch 500 into the exhaust steam main pipe 300.

The exhaust bypass 600 can lead to the condenser 13, and part of the exhaust steam in the exhaust steam main pipe 300 of the small steam turbine 1 can be introduced into the condenser 13 through the exhaust bypass 600 to be condensed to form condensed water. The exhaust gas bypass 600 may not be routed to the condenser 13, but may be directly evacuated. The opening or closing of the exhaust bypass valve 11 on the exhaust bypass 600 can control the on-off of the exhaust bypass 600, and the exhaust bypass valve 11 can be a shut-off valve, which can be a stop valve, a gate valve or a butterfly valve, for example. In the starting stage, the steam extraction pipeline 200, the regenerative branch 400 and the overflow branch 500 can be disconnected, the steam exhaust bypass 600 can be opened, after the small steam turbine 1 is fully loaded with a certain load, the regenerative branch 400 and each stage of steam extraction pipelines 200 are opened step by step, and the steam exhaust bypass 600 is disconnected, so that the small steam turbine 1 operates under the normal working condition, and the small steam turbine 1 can be stably started.

To ensure the operation safety, the steam exhaust main pipe 300 may be provided with a first steam exhaust safety valve 16.

In this embodiment, preferably, the steam exhaust main pipe 300 may be provided with a mixing header 17, and the steam exhaust branch is communicated with the mixing header 17. The exhaust steam main pipe 300 sends the exhaust steam at the exhaust steam outlet of the small steam turbine 1 into the mixing header 17, the regenerative branch 400, the overflow branch 500 and the exhaust steam bypass 600 are all communicated with the mixing header 17, and the exhaust steam in the mixing header 17 can be respectively exhausted through the regenerative branch 400, the overflow branch 500 and the exhaust steam bypass 600. Preferably, the mixing header 17 is provided with a steam exhaust safety branch 700, and the steam exhaust safety branch 700 is provided with a second steam exhaust safety valve 18.

Further, the backheating steam extraction system of the back pressure small turbine of the embodiment further includes an auxiliary steam source 19, the auxiliary steam source 19 is communicated with the steam exhaust main pipe 300 through a steam supplementing pipe 800, and the steam supplementing valve 20 is arranged on the steam supplementing pipe 800. The steam pressure of the auxiliary steam source 19 is higher than the conventional backpressure of the small steam turbine 1, so that when the steam supplementing pipeline 800 is opened, the auxiliary steam in the auxiliary steam source 19 can be sent into the steam exhaust main pipeline 300, and the purpose of increasing the pressure of the steam exhaust main pipeline 300 is achieved. When the mixed header 17 is arranged on the steam exhaust main pipeline 300, the steam supplementing pipeline 800 is communicated with the mixed header 17. The on-off of the steam supplementing pipeline 800 can be controlled by opening or closing the steam supplementing valve 20, and meanwhile, the auxiliary steam flow in the steam supplementing pipeline 800 can be adjusted by adjusting the opening of the steam supplementing valve 20 so as to control the pressure of the steam exhaust main pipeline 300. Preferably, the steam supplementing valve 20 is a shut-off regulating valve, the steam supplementing valve 20 may be a valve having both shut-off and opening regulating functions, the steam supplementing valve 20 may also be a valve group formed by connecting a steam supplementing shut-off valve 201 and a steam supplementing regulating valve 202 in series, the on-off of the steam supplementing pipeline 800 is controlled by opening or closing the steam supplementing shut-off valve 201, and the auxiliary steam flow in the steam supplementing pipeline 800 is controlled by regulating the opening of the steam supplementing regulating valve 202. The make-up shutoff valve 201 may be in the form of, but is not limited to, a shut-off valve, a gate valve, or a butterfly valve, for example. Preferably, the steam supply pipe 800 may be provided with a steam supply check valve 21 for preventing the exhaust steam and the auxiliary steam from flowing back into the auxiliary steam source 19 from the steam supply pipe 800.

In this embodiment, the pressure of the steam exhaust main pipe 300 (or the mixing header 17) can be adjusted by the steam supplement valve 20 on the steam supplement pipe 800 and the steam exhaust valve on the steam exhaust branch together, so that the back pressure of the small steam turbine 1 can be indirectly adjusted.

In this embodiment, the first heater 3 may be a regenerative heater or a deaerator, the second heater 8 may be a regenerative heater or a deaerator, and the third heater 12 may be a regenerative heater or a deaerator.

Next, a preferred embodiment of the regenerative steam extraction system of the low back pressure turbine according to the present embodiment will be described with reference to fig. 2 to 6.

Fig. 2 shows a first embodiment of the regenerative steam extraction system of the low back pressure turbine of the present embodiment. In the first embodiment, the steam inlet of the small turbine 1 is communicated with the steam supply pipeline 100, the steam supply pipeline 100 is provided with the main steam valve 41 and the steam inlet regulating valve 42, the operating mechanism 2 is a water supply pump, and the water supply pump is connected with the small turbine 1. The first heaters 3 are three, the pressure of the three first heaters 3 is gradually increased along the water supply flow direction, three steam extraction ports are arranged on the small steam turbine 1, each steam extraction port is communicated with the corresponding first heater 3 through a steam extraction pipeline 200, and each steam extraction pipeline 200 is provided with a steam extraction valve 5 and a steam extraction check valve 6. The mixed steam collecting box 17 is arranged on the steam exhaust main pipeline 300 of the small steam turbine 1, the first steam exhaust safety valve 16 and the steam exhaust check valve 7 are arranged on the steam exhaust main pipeline 300 at the upstream of the mixed steam collecting box 17, the steam exhaust safety branch 700 is arranged on the mixed steam collecting box 17, and the second steam exhaust safety valve 18 is arranged on the steam exhaust safety branch 700. The heat return branch 400, the overflow branch 500 and the steam exhaust bypass 600 are all communicated with the mixing header 17. The regenerative branch 400 is communicated with the second heater 8, and a regenerative steam extraction valve 9 and a regenerative steam extraction check valve 14 are arranged on the regenerative branch 400. The overflow branch 500 is connected to the third heater 12, the overflow shutoff valve 101, the overflow regulating valve 102 and the overflow check valve 15 are arranged on the overflow branch 500, and the main turbine extraction steam pipeline 900 sends the main turbine extraction steam to the third heater 12. The exhaust bypass 600 leads to the condenser 13, and the exhaust bypass 600 is provided with an exhaust bypass valve 11. The auxiliary steam source 19 is communicated with the mixing header 17 through a steam supplementing pipeline 800, and a steam supplementing shutoff valve 201, a steam supplementing regulating valve 202 and a steam supplementing check valve 21 are arranged on the steam supplementing pipeline 800.

The working principle of the first implementation mode of the back-pressure small steam turbine regenerative steam extraction system in the embodiment is as follows: at the starting stage of the small steam turbine 1, the steam extraction valves 5 on the steam extraction pipelines 200 are all closed, the regenerative steam extraction valve 9 on the regenerative branch 400 is closed, the overflow shutoff valve 101 and the overflow regulating valve 102 on the overflow branch 500 are all closed, the steam compensation shutoff valve 201 and the steam compensation regulating valve 202 on the steam compensation pipeline 800 are all closed, the steam exhaust bypass valve 11 on the steam exhaust bypass 600 is opened, the main steam valve 41 and the steam inlet regulating valve 42 on the steam supply pipeline 100 are opened, so that all the steam discharged from the small steam turbine 1 at the starting initial stage is discharged into the condenser 13 through the steam exhaust bypass 600, and at this time, the small steam turbine 1 operates in a condensing mode. When the small turbine 1 rises to a set load, the exhaust bypass valve 11 on the exhaust bypass 600 is closed, and the regenerative steam extraction valve 9 on the regenerative branch 400 and the steam extraction valve 5 on each steam extraction pipeline 200 are sequentially opened step by step, so that the second heater 8 and each first heater 3 are sequentially put into operation step by step from low to high in pressing force, and the small turbine 1 enters normal working condition operation. During the operation of the small steam turbine 1, the following operations may be performed according to actual conditions.

When the opening degree of the steam inlet regulating valve 42 on the steam supply pipeline 100 is small and the throttling phenomenon is serious, the back pressure of the small steam turbine 1 needs to be properly increased, at this time, the steam supply shutoff valve 201 and the steam supply regulating valve 202 on the steam supply pipeline 800 can be opened, so that auxiliary steam in the auxiliary steam source 19 enters the mixing header 17, the pressure of the mixing header 17 is increased, and the back pressure of the small steam turbine 1 is also increased. By adjusting the opening of the steam supply regulating valve 202, the auxiliary steam flow entering the mixing header 17 can be controlled, so that the pressure of the mixing header 17, namely the back pressure of the small steam turbine 1, can be controlled.

When the back pressure of the small steam turbine 1 is higher and needs to be reduced, the overflow shutoff valve 101 and the overflow regulating valve 102 on the overflow branch 500 can be opened, the pressure of the mixing header 17 can be reduced by overflowing the overflow branch 500, and then the back pressure of the small steam turbine 1 is also reduced. By adjusting the opening of the relief valve 102, the pressure of the mixing header 17, that is, the back pressure of the small steam turbine 1 can be controlled.

When the second heater 8 has a fault, the regenerative steam extraction valve 9 on the regenerative branch 400 can be closed, the exhaust bypass valve 11 on the exhaust bypass 600 can be opened, and at this time, the exhaust steam of the small steam turbine 1 is discharged into the condenser 13 through the exhaust bypass 600.

When the small turbine 1 needs to further increase the output power under the full load condition, the pressure of the mixing header 17 can be properly reduced, and the back pressure of the small turbine 1 is reduced, so that the output power of the small turbine 1 can be increased to a certain extent. At this time, the overflow shutoff valve 101 and the overflow regulating valve 102 of the overflow branch 500 may be opened, or the exhaust bypass valve 11 of the exhaust bypass 600 may be opened, so that the pressure of the mixing header 17 may be reduced.

When the small steam turbine 1 needs to change the load quickly, the steam inlet amount can be adjusted by adjusting the opening degree of the steam inlet adjusting valve 42 on the steam supply pipeline 100, meanwhile, the back pressure of the small steam turbine 1 can be reduced by taking the adjustment of the back pressure of the small steam turbine 1 as an auxiliary means, the output power of the small steam turbine 1 can be improved, the back pressure of the small steam turbine 1 can be improved, the output power of the small steam turbine 1 can be reduced, and therefore the operation load of the small steam turbine 1 can be adjusted quickly in an auxiliary mode.

Therefore, according to the first embodiment of the regenerative steam extraction system of the back pressure small steam turbine of the embodiment, the steam supplementing pipeline 800, the overflow branch 500 and the steam exhaust bypass 600 are arranged on the steam exhaust side of the small steam turbine 1, so that a set of complete steam supplementing, overflowing and bypassing system is formed, and flexible operation can be realized by matching and adjusting the steam supplementing valve 20 (the steam supplementing shutoff valve 201 and the steam supplementing adjusting valve 202), the overflow valve 10 (the overflow shutoff valve 101 and the overflow adjusting valve 102) and the steam exhaust bypass valve 11, so that the system is adapted to the initial starting stage and various operation conditions of the small steam turbine 1, safe and stable operation of the system is ensured, adjustment of the back pressure of the small steam turbine 1 is realized, and the purpose of improving the efficiency of the small steam turbine 1 to the maximum extent is achieved.

Fig. 3 shows a second embodiment of the regenerative steam extraction system of the low back pressure turbine according to this embodiment. The second embodiment is basically the same as the first embodiment, and the same parts are not described again, but the difference is that in the second embodiment, the auxiliary steam source 19, the steam supply pipeline 800, the steam supply shutoff valve 201, the steam supply regulating valve 202, and the steam supply check valve 21 are not provided, so that the second embodiment can realize the regulating function of reducing the back pressure of the small steam turbine 1, but cannot realize the regulating function of increasing the back pressure of the small steam turbine 1.

Fig. 4 shows a third embodiment of the regenerative steam extraction system of the low back pressure turbine according to this embodiment. The third embodiment is substantially the same as the first embodiment, and the same parts are not described again, except that in the third embodiment, the exhaust bypass 600 is not communicated with the condenser 13, but is directly exhausted.

As shown in fig. 5, a fourth embodiment of the regenerative steam extraction system of the low back pressure turbine of the present embodiment is shown. The fourth embodiment is substantially the same as the first embodiment, and the description of the same parts is omitted, except that in the fourth embodiment, the overflow branch 500 is not led to the third heater 12, but directly exhausted.

Fig. 6 shows a fifth embodiment of the regenerative steam extraction system of the low back pressure turbine according to this embodiment. The fifth embodiment is substantially the same as the first embodiment, and the same parts are not described again, except that in the fifth embodiment, the steam exhaust main pipe 300 is not provided with the mixing header 17, and the heat recovery branch 400, the overflow branch 500, the steam exhaust bypass 600, and the steam supply pipe 800 are directly communicated with the steam exhaust main pipe 300.

To sum up, the back pressure small steam turbine regenerative steam extraction system of this embodiment sets up extraction pipeline 200 on small steam turbine 1, provides regenerative steam extraction for first heater 3, sets up the exhaust branch to the exhaust user on small steam turbine 1 exhaust main pipe 300, adjusts through the cooperation of extraction valve 5 on extraction pipeline 200 and the exhaust valve on the exhaust branch, can realize nimble operation, adapts to small steam turbine 1 and starts initial stage and various operating condition, guarantees that the system operates safely and stably, realizes the adjustment to small steam turbine 1 back pressure simultaneously, reaches the purpose that the at utmost improves small steam turbine 1 efficiency.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of modifications and replacements can be made without departing from the technical principle of the present invention, and these modifications and replacements should also be regarded as the protection scope of the present invention.

Claims (10)

1. The utility model provides a little steam turbine of backpressure backheat steam extraction system, its characterized in that, includes little steam turbine (1), operating device (2) and at least one first heater (3), operating device (2) with little steam turbine (1) is connected, little steam turbine (1) is equipped with at least one extraction steam port, the extraction steam port with first heater (3) one-to-one and be linked together through extraction steam pipe way (200), be equipped with extraction steam valve (5) on extraction steam pipe way (200), the extraction steam port of little steam turbine (1) is equipped with exhaust steam main pipe way (300), be equipped with the exhaust steam branch way to the exhaust user on exhaust steam main pipe way (300), be equipped with the exhaust steam valve on the exhaust branch way.

2. The back pressure small steam turbine regenerative steam extraction system according to claim 1, characterized in that the steam exhaust branch comprises a regenerative branch (400) in which the steam exhaust pressure is reduced in sequence, an overflow branch (500) and a steam exhaust bypass (600), the regenerative branch (400) leads to the second heater (8), and the steam exhaust valve comprises a regenerative steam extraction valve (9) arranged on the regenerative branch (400), an overflow valve (10) arranged on the overflow branch (500) and a steam exhaust bypass valve (11) arranged on the steam exhaust bypass (600).

3. The regenerative steam extraction system of a low back pressure turbine according to claim 2, wherein the overflow branch (500) is routed to a third heater (12) or vented.

4. The regenerative steam extraction system of a low back pressure turbine as claimed in claim 3, wherein the source of heated steam for the third heater (12) is provided by a main turbine extraction.

5. The backpressure steam turbine regenerative steam extraction system according to claim 2, wherein the exhaust bypass (600) leads to a condenser (13) or is exhausted.

6. The regenerative steam extraction system of a low back pressure turbine as claimed in claim 1, wherein the steam exhaust main pipe (300) is provided with a first steam exhaust safety valve (16).

7. The regenerative steam extraction system of the back pressure small turbine according to claim 1, wherein a mixing header tank (17) is arranged on the steam exhaust main pipe (300), and the steam exhaust branch is communicated with the mixing header tank (17).

8. The regenerative steam extraction system of the back pressure small turbine according to claim 7, wherein the mixing header (17) is provided with a steam discharge safety branch (700), and the steam discharge safety branch (700) is provided with a second steam discharge safety valve (18).

9. The backpressure small steam turbine regenerative steam extraction system according to claim 1, further comprising an auxiliary steam source (19), wherein the auxiliary steam source (19) is communicated with the steam exhaust main pipeline (300) through a steam supplementing pipeline (800), and a steam supplementing valve (20) is arranged on the steam supplementing pipeline (800).

10. The regenerative steam extraction system of the back pressure small turbine according to claim 1, wherein the steam extraction pipeline (200) is provided with a steam extraction check valve (6), and the steam exhaust main pipeline (300) is provided with a steam exhaust check valve (7).

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