Steam source switching system for water feeding pump turbine of thermal power generating unit

Abstract

The utility model provides a steam source switching system for a water feeding pump turbine of a thermal power generating unit, and relates to the technical field of thermal power generation. The system comprises an auxiliary steam header connected with a water feed pump turbine through a pipeline; the low-pressure steam extraction subunit is used for conveying low-pressure extracted steam to the auxiliary steam header and adjusting the flow of the low-pressure extracted steam; the cold re-extraction main unit is used for conveying cold re-extraction steam to the auxiliary steam header and coarsely adjusting the flow of the cold re-extraction steam; the cold re-extraction steam subunit is used for conveying cold re-extraction steam to the auxiliary steam header and finely adjusting the flow of the cold re-extraction steam; the auxiliary steam header is used for balancing the pressure of low-pressure extraction steam and / or cold re-extraction steam entering the auxiliary steam header to form mixed extraction steam and mixed drain water; and the low-pressure steam extraction main unit is used for conveying low-pressure extracted steam to the water feed pump turbine and adjusting the flow of the low-pressure extracted steam. The system solves the problem that in the prior art, after a thermal power generating unit cancels a high-pressure steam inlet pipe section entering a water feeding pump steam turbine, cold re-extraction steam entering an auxiliary steam header is likely to be excessive, and consequently the peak regulation response speed of the thermal power generating unit is low.

Description

Technical Field

[0001] The utility model relates to the technical field of thermal power generation, in particular to a steam source switching system for a feedwater pump steam turbine of a thermal power unit. Background Art

[0002] In the early stage of construction, the long-term peak-shaving operation state of 50% and below load was rarely considered in the early stage of construction of early thermal power units, resulting in the cancellation of the high-pressure steam inlet pipe section of the cold re-extraction steam source directly entering the feedwater pump turbine during the design optimization process. In the actual peak-shaving process, the cold re-extraction steam as a high-pressure steam source can only enter the auxiliary steam header first, and then enter the feedwater pump turbine and / or the auxiliary steam system of the thermal power unit after passing through the auxiliary steam header. At present, the steam flow rate designed in the pipeline for the cold re-extraction steam to enter the auxiliary steam header is relatively large. When supplementing the small-flow high-pressure steam source, the regulation characteristics of the electric valve at a small opening are poor. The cold re-extraction steam entering the auxiliary steam header is easy to exceed the amount. When the auxiliary steam header sends a small steam flow to other systems of the thermal power unit, it is very easy to cause the auxiliary steam header to be over-pressurized, causing safety risks. At the same time, it also greatly affects the switching of the high-pressure and low-pressure steam sources of the feedwater pump turbine, reducing the response speed of the unit during the peak-shaving process. Therefore, a device is urgently needed to solve at least one of the above problems. Utility Model Content

[0003] The purpose of the embodiment of the utility model is to provide a steam source switching system for a feedwater pump turbine of a thermal power unit, which is used to solve the problem in the prior art that after the high-pressure steam inlet pipe section entering the feedwater pump turbine of the thermal power unit is cancelled, the cold re-extraction steam entering the auxiliary steam header is easily excessive, thereby causing a slow peak-shaving response speed of the thermal power unit.

[0004] In order to achieve the above-mentioned purpose, the utility model provides a feedwater pump steam turbine steam source switching system for a thermal power unit, which is connected to the feedwater pump steam turbine. The feedwater pump steam turbine steam source switching system for a thermal power unit comprises:

[0005] The auxiliary steam header is connected to the feedwater pump turbine through a pipeline;

[0006] The low-pressure extraction steam subunit is used to transport the low-pressure extraction steam to the auxiliary steam header and adjust the flow rate of the low-pressure extraction steam entering the auxiliary steam header;

[0007] A cold re-extraction steam main unit, used for conveying cold re-extraction steam to the auxiliary steam header and roughly adjusting the flow rate of the cold re-extraction steam entering the auxiliary steam header;

[0008] A cold re-extraction steam sub-unit, used for conveying cold re-extraction steam to the auxiliary steam header and finely adjusting the flow rate of cold re-extraction steam entering the auxiliary steam header;

[0009] The auxiliary steam header is used to balance the pressure of the low-pressure extraction steam and / or cold re-extraction steam entering the auxiliary steam header to form mixed extraction steam and mixed drainage, and send the mixed extraction steam into the feedwater pump turbine.

[0010] The low-pressure extraction steam main unit is used to transport low-pressure extraction steam to the feedwater pump turbine and adjust the flow rate of low-pressure extraction steam entering the feedwater pump turbine.

[0011] Specifically, the feedwater pump turbine steam source switching system of the thermal power unit further includes: a drain unit connected to the auxiliary steam header and used for discharging mixed drain in the auxiliary steam header.

[0012] Specifically, the drain unit includes: a drain pipe and a drain electric valve;

[0013] One end of the drain pipe is connected to the drain outlet of the auxiliary steam header, and the other end is connected to the drain recovery device, and the mixed drain is discharged to the drain recovery device through the drain pipe;

[0014] The drain electric valve is arranged on the drain pipe and is used to control the flow state of the mixed drain in the drain pipe.

[0015] Specifically, the feedwater pump turbine steam source switching system of the thermal power unit further includes: an auxiliary steam unit connected to the auxiliary steam header and used for delivering the mixed extraction steam to the steam-consuming equipment.

[0016] Specifically, the auxiliary steam unit includes: an auxiliary steam pipeline and an auxiliary steam electric valve;

[0017] One end of the auxiliary steam pipeline is connected to the auxiliary steam header, and the other end is connected to the steam-consuming equipment, and the mixed extraction steam is transported to the steam-consuming equipment through the auxiliary steam pipeline;

[0018] The auxiliary steam electric valve is arranged on the auxiliary steam pipeline, and is used to control the flow state of the mixed extraction steam in the auxiliary steam pipeline.

[0019] Specifically, the feedwater pump turbine steam source switching system of the thermal power unit also includes: a mixing regulating valve, which is arranged on the pipeline between the auxiliary steam header and the feedwater pump turbine and is used to adjust the flow rate of the mixed extraction steam entering the feedwater pump turbine.

[0020] Specifically, the low-pressure steam extraction main unit comprises: a low-pressure steam extraction main pipeline, a first check valve and a first regulating valve;

[0021] One end of the low-pressure steam extraction main pipeline is connected to the low-pressure steam extraction supply device, and the other end is connected to the feedwater pump steam turbine, and the low-pressure steam extraction is transported to the feedwater pump steam turbine through the low-pressure steam extraction main pipeline;

[0022] The first check valve is arranged on the low-pressure steam extraction main pipeline, and is used to control the flow direction of the low-pressure steam extraction in the low-pressure steam extraction main pipeline;

[0023] The first regulating valve is arranged on the low-pressure extraction steam main pipeline, and is used for regulating the flow rate of the low-pressure extraction steam entering the feedwater pump turbine.

[0024] Specifically, the low-pressure steam extraction sub-unit comprises: a low-pressure steam extraction sub-pipeline, a second check valve and a second regulating valve;

[0025] One end of the low-pressure steam extraction sub-pipeline is connected to the low-pressure steam extraction supply device, and the other end is connected to the auxiliary steam header, and the low-pressure steam extraction is transported to the auxiliary steam header through the low-pressure steam extraction sub-pipeline;

[0026] The second check valve is arranged on the low-pressure steam extraction sub-pipeline, and is used to control the flow direction of the low-pressure steam extraction in the low-pressure steam extraction sub-pipeline;

[0027] The second regulating valve is arranged on the low-pressure steam extraction sub-pipeline, and is used for regulating the flow rate of the low-pressure steam extraction entering the auxiliary steam header.

[0028] Specifically, the cold re-extraction steam main unit comprises: a cold re-extraction steam main pipeline and a third regulating valve;

[0029] One end of the cold re-extraction steam main pipeline is connected to the cold re-extraction steam supply device, and the other end is connected to the auxiliary steam header, and the cold re-extraction steam is transported to the auxiliary steam header through the cold re-extraction steam main pipeline;

[0030] The third regulating valve is arranged on the cold re-extraction steam main pipeline, and is used for regulating the flow rate of the cold re-extraction steam entering the auxiliary steam header.

[0031] Specifically, the cold re-extraction sub-unit comprises: a cold re-extraction sub-pipeline, a third check valve and a fourth regulating valve;

[0032] One end of the cold re-extraction steam sub-pipeline is connected to the cold re-extraction steam supply device, and the other end is connected to the auxiliary steam header, and the cold re-extraction steam is transported to the auxiliary steam header through the cold re-extraction steam sub-pipeline;

[0033] The third check valve is arranged on the cold re-extraction steam auxiliary sub-channel, and is used to control the flow direction of the cold re-extraction steam in the cold re-extraction steam sub-channel;

[0034] The fourth regulating valve is arranged on the cold re-extraction steam sub-pipeline, and is used for finely adjusting the flow rate of the cold re-extraction steam entering the auxiliary steam header.

[0035] The utility model provides a steam source switching system for a feedwater pump turbine of a thermal power unit, wherein a low-pressure steam extraction main unit transmits low-pressure extraction steam to the feedwater pump turbine and adjusts the flow rate of the low-pressure extraction steam sent to the feedwater pump turbine, a low-pressure steam extraction sub-unit transmits low-pressure extraction steam to an auxiliary steam header and adjusts the flow rate of the low-pressure extraction steam sent to the auxiliary steam header, a cold re-extraction main unit transmits cold re-extraction steam to the auxiliary steam header and roughly adjusts the flow rate of the cold re-extraction steam sent to the auxiliary steam header, and a cold re-extraction sub-unit transmits cold re-extraction steam to the auxiliary steam header and finely adjusts the flow rate of the cold re-extraction steam sent to the auxiliary steam header, so that the steam volume of the cold re-extraction steam entering the auxiliary steam header is controlled, that is, the steam volume of the cold re-extraction steam as a high-pressure steam source entering the auxiliary steam header can be accurately controlled. , avoiding excessive cold re-extraction steam entering the auxiliary steam header, and also making the proportion of cold re-extraction steam in the final mixed extraction steam be accurately controlled, so that the mixed extraction steam formed by low-pressure extraction steam and cold re-extraction steam can assist the thermal power unit to quickly and stably perform peak regulation. By controlling the low-pressure extraction main unit, the low-pressure extraction sub-unit, the cold re-extraction main unit and the cold re-extraction sub-unit to transport low-pressure extraction steam and cold re-extraction steam to the feedwater pump turbine, the thermal power unit can adapt to the steam demand of different load sections, solving the problem in the prior art that the cold re-extraction steam entering the auxiliary steam header after the thermal power unit cancels the high-pressure steam inlet pipe section entering the feedwater pump turbine is prone to excessive cold re-extraction, thereby resulting in slow peak regulation response speed of the thermal power unit.

[0036] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are used to provide a further understanding of the embodiments of the present utility model and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present utility model, but do not constitute a limitation on the embodiments of the present utility model. In the accompanying drawings:

[0038] Figure 1 It is a schematic layout diagram of a steam source switching system for a feedwater pump turbine of a thermal power unit provided by an embodiment of the utility model.

[0039] Description of Reference Numerals

[0040] 1-first check valve; 2-first regulating valve; 3-feedwater pump turbine; 4-second check valve; 5-second regulating valve; 6-auxiliary steam header; 7-third regulating valve; 8-mixing regulating valve; 9-third check valve; 10-fourth regulating valve; 11-drain electric valve; 12-auxiliary steam electric valve; 13-low-pressure steam extraction main unit; 14-low-pressure steam extraction sub-unit; 15-cold re-extraction main unit; 16-cold re-extraction sub-unit. DETAILED DESCRIPTION

[0041] The specific implementation of the embodiment of the utility model is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the utility model, and is not used to limit the embodiment of the utility model.

[0042] Figure 1 This is a schematic diagram of the layout of the steam source switching system for the feedwater pump and steam turbine of a thermal power unit. Figure 1 As shown, the utility model provides a feedwater pump steam turbine steam source switching system for a thermal power unit, which is connected to the feedwater pump steam turbine 3. The feedwater pump steam turbine steam source switching system for a thermal power unit includes:

[0043] The auxiliary steam header 6 is connected to the feedwater pump turbine 3 through a pipeline;

[0044] The low-pressure extraction steam subunit 14 is used to transport the low-pressure extraction steam to the auxiliary steam header 6 and adjust the flow rate of the low-pressure extraction steam entering the auxiliary steam header 6;

[0045] The cold re-extraction steam main unit 15 is used to transport the cold re-extraction steam to the auxiliary steam header 6 and roughly adjust the flow rate of the cold re-extraction steam entering the auxiliary steam header 6;

[0046] The cold re-extraction steam sub-unit 16 is used to transport the cold re-extraction steam to the auxiliary steam header 6 and finely adjust the flow rate of the cold re-extraction steam entering the auxiliary steam header 6;

[0047] The auxiliary steam header 6 is used to balance the pressure of the low-pressure extraction steam and / or cold re-extraction steam entering the auxiliary steam header 6 to form mixed extraction steam and mixed drainage, and send the mixed extraction steam to the feedwater pump turbine 3;

[0048] The low-pressure extraction steam main unit 13 is used to transport the low-pressure extraction steam to the feedwater pump steam turbine 3 and adjust the flow rate of the low-pressure extraction steam entering the feedwater pump steam turbine 3.

[0049] The utility model provides a feedwater pump steam turbine steam source switching system for a thermal power unit. In the case that the feedwater pump steam turbine 3 has no high-pressure steam source pipe section, the low-pressure extraction steam is transmitted to the feedwater pump steam turbine 3 through the low-pressure extraction main unit 13 and the flow rate of the low-pressure extraction steam sent to the feedwater pump steam turbine 3 is adjusted. The low-pressure extraction steam serves as the low-pressure steam source of the feedwater pump steam turbine 3. The low-pressure extraction steam sub-unit 14 transmits the low-pressure extraction steam to the auxiliary steam header 6 and adjusts the flow rate of the low-pressure extraction steam entering the auxiliary steam header 6. The cold re-extraction steam main unit 15 transmits the cold re-extraction steam to the auxiliary steam header 6 and roughly adjusts the flow rate of the cold re-extraction steam sent to the auxiliary steam header 6. The cold re-extraction steam sub-unit 16 transmits the cold re-extraction steam to the auxiliary steam header 6 and finely adjusts the flow rate of the cold re-extraction steam sent to the auxiliary steam header 6. The cold re-extraction steam serves as the high-pressure steam source. The auxiliary steam header 6 performs pressure balance on the incoming low-pressure extraction steam and the cold re-extraction steam. After the pressure balance, the low-pressure extraction steam is High-pressure extraction steam and cold re-extraction steam become mixed extraction steam and enter the feedwater pump steam turbine 3. The flow rate of cold re-extraction steam entering the auxiliary steam header 6 can be accurately controlled through coarse adjustment and fine adjustment, thereby avoiding excessive cold re-extraction steam entering the auxiliary steam header, and also making the occupancy of cold re-extraction steam in the finally formed mixed extraction steam be accurately controlled. In practical applications, the low-pressure extraction steam main unit 13, the low-pressure extraction steam sub-unit 14, the cold re-extraction steam main unit 15 and the cold re-extraction steam sub-unit 16 are controlled according to the actual load of the thermal power unit to finally deliver the low-pressure extraction steam and cold re-extraction steam to the feedwater pump steam turbine 3, which can enable the thermal power unit to quickly respond to the steam demand when the load changes, and solves the problem in the prior art that the cold re-extraction steam entering the auxiliary steam header after the thermal power unit cancels the high-pressure steam inlet pipe section entering the feedwater pump steam turbine is prone to excessive, thereby resulting in a slow peak-shaving response speed of the thermal power unit.

[0050] When the pressure of low-pressure extraction steam and cold re-extraction steam is balanced in the auxiliary steam header 6, mixed drain will also be generated. In order to avoid the mixed drain occupying the storage capacity of the mixed extraction steam, the steam source switching system of the feed water pump turbine of the thermal power unit also includes: a drain unit, which is connected to the auxiliary steam header 6 and is used to discharge the mixed drain in the auxiliary steam header 6.

[0051] The drain unit comprises: a drain pipe and a drain electric valve 11;

[0052] One end of the drain pipe is connected to the drain outlet of the auxiliary steam header 6, and the other end is connected to the drain recovery device, and the mixed drain is discharged to the drain recovery device through the drain pipe;

[0053] The drain electric valve 11 is arranged on the drain pipe, and is used to control the flow state of the mixed drain in the drain pipe.

[0054] like Figure 1As shown, a drain pipe is connected to the drain outlet of the auxiliary steam header 6, and the drain pipe is also connected to a drain recovery device. A drain electric valve 11 is arranged on the drain pipe. When the drain electric valve 11 is opened, the mixed drain can be discharged from the auxiliary steam header 6, and flows through the drain outlet and the drain pipe of the auxiliary steam header 6 into the drain recovery device. When the drain electric valve 11 is closed, the mixed drain cannot flow in the drain pipe, and the mixed drain cannot be discharged from the auxiliary steam header 6.

[0055] In order to improve the utilization rate of the mixed extraction steam, the feedwater pump turbine steam source switching system of the thermal power unit further includes: an auxiliary steam unit connected to the auxiliary steam header 6 and used for conveying the mixed extraction steam to the steam-consuming equipment.

[0056] The auxiliary steam unit comprises: an auxiliary steam pipeline and an auxiliary steam electric valve 12;

[0057] One end of the auxiliary steam pipeline is connected to the auxiliary steam header 6, and the other end is connected to the steam-consuming equipment, and the mixed extraction steam is transported to the steam-consuming equipment through the auxiliary steam pipeline;

[0058] The auxiliary steam electric valve 12 is arranged on the auxiliary steam pipeline, and is used to control the flow state of the mixed extraction steam in the auxiliary steam pipeline.

[0059] The low-pressure extraction steam and the cold re-extraction steam are pressure-balanced by the auxiliary steam manifold 6 to form mixed extraction steam, which is transported as auxiliary steam to other steam-consuming equipment in the thermal power unit through the auxiliary steam pipeline, thereby improving energy utilization. An auxiliary steam electric valve 12 is arranged on the auxiliary steam pipeline. When the auxiliary steam electric valve 12 is opened, the mixed extraction steam can be discharged from the auxiliary steam manifold 6 and enter other steam-consuming equipment in the thermal power unit through the auxiliary steam pipeline. When the auxiliary steam electric valve 12 is closed, the mixed extraction steam cannot enter other steam-consuming equipment through the auxiliary steam pipeline.

[0060] In order to control the amount of mixed extraction steam entering the feedwater pump steam turbine 3, the feedwater pump steam turbine steam source switching system of the thermal power unit further includes: a mixed regulating valve 8, which is arranged on the pipeline between the auxiliary steam header 6 and the feedwater pump steam turbine 3, and is used to adjust the flow of mixed extraction steam entering the feedwater pump steam turbine 3. A pipeline is arranged between the outlet of the mixed extraction steam of the auxiliary steam header 6 and the air inlet of the feedwater pump steam turbine 3, and the mixed regulating valve 8 arranged on the pipeline between the auxiliary steam header 6 and the feedwater pump steam turbine 3 is used to adjust the flow of mixed extraction steam entering the feedwater pump steam turbine 3 through the pipeline, thereby accurately controlling the steam consumption of the thermal power unit during the peak load regulation process.

[0061] In one embodiment, Figure 1 As shown, the low-pressure steam extraction main unit 13 includes: a low-pressure steam extraction main pipeline, a first check valve 1 and a first regulating valve 2;

[0062] One end of the low-pressure steam extraction main pipeline is connected to the low-pressure steam extraction supply device, and the other end is connected to the feedwater pump steam turbine 3, and the low-pressure steam extraction is transported to the feedwater pump steam turbine 3 through the low-pressure steam extraction main pipeline;

[0063] The first check valve 1 is arranged on the low-pressure steam extraction main pipeline, and is used to control the flow direction of the low-pressure steam extraction in the low-pressure steam extraction main pipeline;

[0064] The first regulating valve 2 is arranged on the low-pressure extraction steam main pipeline, and is used to adjust the flow rate of the low-pressure extraction steam entering the feedwater pump turbine 3.

[0065] The low-pressure steam extraction sub-unit 14 comprises: a low-pressure steam extraction sub-pipeline, a second check valve 4 and a second regulating valve 5;

[0066] One end of the low-pressure steam extraction sub-pipeline is connected to the low-pressure steam extraction supply device, and the other end is connected to the auxiliary steam header 6, and the low-pressure steam extraction is transported to the auxiliary steam header 6 through the low-pressure steam extraction sub-pipeline;

[0067] The second check valve 4 is arranged on the low-pressure steam extraction sub-pipeline, and is used to control the flow direction of the low-pressure steam extraction in the low-pressure steam extraction sub-pipeline;

[0068] The second regulating valve 5 is arranged on the low-pressure steam extraction sub-pipeline, and is used to adjust the flow rate of the low-pressure steam extraction entering the auxiliary steam header 6 .

[0069] The cold re-extraction main unit 15 comprises: a cold re-extraction main pipeline and a third regulating valve 7;

[0070] One end of the cold re-extraction steam main pipeline is connected to the cold re-extraction steam supply device, and the other end is connected to the auxiliary steam header 6, and the cold re-extraction steam is transported to the auxiliary steam header 6 through the cold re-extraction steam main pipeline;

[0071] The third regulating valve 7 is arranged on the cold re-extraction steam main pipeline, and is used for roughly adjusting the flow rate of the cold re-extraction steam entering the auxiliary steam header 6 .

[0072] The cold re-extraction sub-unit 16 comprises: a cold re-extraction sub-pipeline, a third check valve 9 and a fourth regulating valve 10;

[0073] One end of the cold re-extraction steam sub-pipeline is connected to the cold re-extraction steam supply device, and the other end is connected to the auxiliary steam header 6, and the cold re-extraction steam is transported to the auxiliary steam header 6 through the cold re-extraction steam sub-pipeline;

[0074] The third check valve 9 is arranged on the cold re-extraction steam sub-pipeline, and is used to control the flow direction of the cold re-extraction steam in the cold re-extraction steam sub-pipeline;

[0075] The fourth regulating valve 10 is arranged on the cold re-extraction steam sub-pipeline, and is used for finely adjusting the flow rate of the cold re-extraction steam entering the auxiliary steam header 6 .

[0076] The following is an explanation of the working status of each unit in the feedwater pump turbine steam source switching system of the thermal power unit at different load stages:

[0077] When the thermal power unit is working in the medium and high load section, the low-pressure extraction steam can meet the steam demand of the feedwater pump turbine and other steam-consuming equipment. At this time, the first regulating valve 2, the second regulating valve 5 and the auxiliary steam electric valve 12 are all opened. In this way, the low-pressure extraction steam delivered by the low-pressure extraction main unit 13 is delivered to the feedwater pump turbine 3, and the low-pressure extraction steam delivered by the low-pressure extraction sub-unit 14 first enters the auxiliary steam header 6. The low-pressure extraction steam is processed by the balanced pressure of the auxiliary steam header 6 to become mixed extraction steam, and then the mixed extraction steam is The steam is delivered to the feedwater pump steam turbine 3 and other steam-consuming equipment of the thermal power unit. At this time, the driving steam source of the feedwater pump steam turbine 3 mainly comes from the low-pressure extraction steam delivered by the low-pressure extraction steam main unit 13 and the low-pressure extraction steam sub-unit 14. The first check valve 1 arranged on the low-pressure extraction steam main pipeline can prevent the low-pressure extraction steam flowing to the feedwater pump steam turbine 3 from flowing back, and the second check valve 4 arranged on the low-pressure extraction steam sub-pipeline can prevent the low-pressure extraction steam flowing to the auxiliary steam manifold 6 from flowing back.

[0078] When the load of the thermal power unit drops to 40%, a high-pressure cold source is required to participate in the peak regulation of the unit. At this time, the fourth regulating valve 10 is gradually opened, and the valve core opening of the fourth regulating valve 10 is gradually increased, so that the flow rate of the cold re-extraction steam delivered by the cold re-extraction sub-unit 16 into the auxiliary steam header 6 is gradually increased. At this time, the drain electric valve 11 is opened synchronously, and the drain electric valve 11 is closed after the mixed drain accumulated in the auxiliary steam header 6 is emptied, and then the mixing regulating valve 8 is opened. In this way, the cold re-extraction steam as a high-pressure steam source is pressure-balanced after the auxiliary steam header 6 to become mixed extraction steam and enter the feed water pump turbine 3. At this time, the driving steam source of the feed water pump turbine 3 mainly comes from the cold re-extraction steam delivered by the cold re-extraction sub-unit 16.

[0079] When the load of the thermal power unit drops to 30%, the first regulating valve 2, the second regulating valve 5, the fourth regulating valve 10, the auxiliary steam electric valve 12 and the mixing regulating valve 8 are all opened. At this time, the low-pressure extraction steam delivered by the low-pressure extraction main unit 13 is sent to the feedwater pump turbine 3, the low-pressure extraction steam delivered by the low-pressure extraction sub-unit 14 enters the auxiliary steam header 6, and the cold re-extraction steam delivered by the cold re-extraction sub-unit 16 enters the auxiliary steam header 6. The low-pressure extraction steam and the cold re-extraction steam are processed by the auxiliary steam header 6 to balance the pressure and become For mixed extraction steam, the mixed extraction steam enters the feedwater pump steam turbine 3 and other steam-consuming equipment, and the flow rate of the mixed extraction steam entering the feedwater pump steam turbine 3 is adjusted by the mixing regulating valve 8. At this time, the driving steam source of the feedwater pump steam turbine 3 mainly comes from the low-pressure extraction steam delivered by the low-pressure extraction main unit 13 and the low-pressure extraction sub-unit 14, and the cold re-extraction steam delivered by the cold re-extraction sub-unit 16. The third check valve 9 arranged on the cold re-extraction sub-pipeline can prevent the cold re-extraction steam from flowing back to the auxiliary steam manifold 6.

[0080] When the load of the thermal power unit continues to decrease to the first load, the first load is lower than 30% of the load, the third regulating valve 7 and the fourth regulating valve 10 are opened, and when the flow of the cold re-extraction steam entering the auxiliary steam header 6 through the cold re-extraction steam main pipeline reaches the maximum flow of the cold re-extraction steam entering the auxiliary steam header 6 through the cold re-extraction steam sub-pipeline, the fourth regulating valve 10 is closed. At this time, the driving steam source of the feedwater pump turbine 3 mainly comes from the cold re-extraction steam delivered by the cold re-extraction steam main unit 15 and the cold re-extraction steam sub-unit 16.

[0081] When the load of the thermal power unit continues to decrease to the second load, the second load is lower than the first load, the first regulating valve 2, the second regulating valve 5, the third regulating valve 7, the mixing regulating valve 8 and the auxiliary steam electric valve 12 are all opened, the low-pressure extraction steam delivered by the low-pressure extraction main unit 13 is sent to the feedwater pump turbine 3, the low-pressure extraction steam delivered by the low-pressure extraction sub-unit 14 enters the auxiliary steam header 6, and the cold re-extraction steam delivered by the cold re-extraction main unit 15 is sent to the auxiliary steam header 6. The auxiliary steam header 6 balances the pressures of the incoming low-pressure extraction steam and the cold re-extraction steam to form a mixed extraction steam, which enters the feedwater pump turbine 3 after the flow rate is adjusted by the mixing regulating valve 8. At this time, the driving steam source of the feedwater pump turbine 3 mainly comes from the low-pressure extraction steam delivered by the low-pressure extraction main unit 13 and the low-pressure extraction sub-unit 14 and the cold re-extraction steam delivered by the cold re-extraction main unit 15. At the same time, the auxiliary steam header 6 can also deliver the mixed extraction steam as auxiliary steam to other steam-consuming equipment of the thermal power unit.

[0082] When the load of the thermal power unit continues to decrease to the third load, the third load is lower than the second load, and the third regulating valve 7, the mixing regulating valve 8 and the auxiliary steam electric valve 12 are all opened. At this time, the cold re-extraction steam transported by the cold re-extraction main unit 14 enters the auxiliary steam manifold 6. After the pressure is balanced in the auxiliary steam manifold 6, the cold re-extraction steam becomes mixed extraction steam and is transported to the feed water pump turbine 3 and other steam-consuming equipment respectively. At this time, the driving air source of the feed water pump turbine 3 mainly comes from the cold re-extraction steam transported by the cold re-extraction main unit 15.

[0083] When the load of the thermal power unit continues to decrease to the fourth load, the fourth load is lower than the third load, and the third regulating valve 7, the fourth regulating valve 10, the mixing regulating valve 8 and the auxiliary steam electric valve 12 are all opened. At this time, the cold re-extraction steam delivered by the cold re-extraction main unit 15 and the cold re-extraction sub-unit 16 forms mixed extraction steam after the pressure is balanced in the auxiliary steam manifold 6. The mixed extraction steam enters the feedwater pump turbine 3 and other steam-consuming equipment, and the flow rate of the mixed extraction steam entering the feedwater pump turbine 3 is adjusted by the mixing regulating valve 8. At this time, the driving steam source of the feedwater pump turbine 3 mainly comes from the cold re-extraction steam delivered by the cold re-extraction main unit 15 and the cold re-extraction sub-unit 16.

[0084] The utility model provides a steam source switching system for a feedwater pump turbine of a thermal power unit, wherein a low-pressure steam extraction main unit transmits low-pressure extraction steam to the feedwater pump turbine and adjusts the flow rate of the low-pressure extraction steam sent to the feedwater pump turbine, a low-pressure steam extraction sub-unit transmits low-pressure extraction steam to an auxiliary steam header and adjusts the flow rate of the low-pressure extraction steam sent to the auxiliary steam header, a cold re-extraction main unit transmits cold re-extraction steam to the auxiliary steam header and roughly adjusts the flow rate of the cold re-extraction steam sent to the auxiliary steam header, and a cold re-extraction sub-unit transmits cold re-extraction steam to the auxiliary steam header and finely adjusts the flow rate of the cold re-extraction steam sent to the auxiliary steam header, so that the steam volume of the cold re-extraction steam entering the auxiliary steam header is controlled, that is, the steam volume of the cold re-extraction steam as a high-pressure steam source entering the auxiliary steam header can be accurately controlled. , avoiding excessive cold re-extraction steam entering the auxiliary steam header, and also making the proportion of cold re-extraction steam in the final mixed extraction steam be accurately controlled, so that the mixed extraction steam formed by low-pressure extraction steam and cold re-extraction steam can assist the thermal power unit to quickly and stably perform peak regulation. By controlling the low-pressure extraction main unit, the low-pressure extraction sub-unit, the cold re-extraction main unit and the cold re-extraction sub-unit to transport low-pressure extraction steam and cold re-extraction steam to the feedwater pump turbine, the thermal power unit can adapt to the steam demand of different load sections, solving the problem in the prior art that the cold re-extraction steam entering the auxiliary steam header after the thermal power unit cancels the high-pressure steam inlet pipe section entering the feedwater pump turbine is prone to excessive cold re-extraction, thereby resulting in slow peak regulation response speed of the thermal power unit.

[0085] The optional implementation modes of the embodiments of the utility model are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the utility model are not limited to the specific details in the above implementation modes. Within the technical concept of the embodiments of the utility model, the technical scheme of the embodiments of the utility model can be subjected to various simple modifications, and these simple modifications all belong to the protection scope of the embodiments of the utility model.

[0086] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the utility model will not further describe various possible combinations.

[0087] In addition, various implementations of the embodiments of the present utility model can also be arbitrarily combined, as long as they do not violate the concept of the embodiments of the present utility model, they should also be regarded as the contents disclosed in the embodiments of the present utility model.

Claims

1. A feedwater pump steam turbine steam source switching system for a thermal power unit, connected to a feedwater pump steam turbine (3), characterized in that: The feedwater pump steam turbine steam source switching system of the thermal power unit comprises: An auxiliary steam header (6) is connected to the feedwater pump steam turbine (3) through a pipeline; A low-pressure extraction steam subunit (14), used for conveying low-pressure extraction steam to the auxiliary steam header (6) and adjusting the flow rate of the low-pressure extraction steam entering the auxiliary steam header (6); A cold re-extraction steam main unit (15) is used to transport the cold re-extraction steam to the auxiliary steam header (6) and roughly adjust the flow rate of the cold re-extraction steam entering the auxiliary steam header (6); a cold re-extraction steam sub-unit (16), used for conveying the cold re-extraction steam to the auxiliary steam header (6) and finely adjusting the flow rate of the cold re-extraction steam entering the auxiliary steam header (6); The auxiliary steam header (6) is used to balance the pressure of the low-pressure extraction steam and / or cold re-extraction steam entering the auxiliary steam header (6) to form mixed extraction steam and mixed drainage, and to send the mixed extraction steam to the feedwater pump turbine (3); The low-pressure extraction steam main unit (13) is used to transport the low-pressure extraction steam to the feedwater pump steam turbine (3) and adjust the flow rate of the low-pressure extraction steam entering the feedwater pump steam turbine (3).

2. The feedwater pump steam turbine steam source switching system for a thermal power unit according to claim 1, characterized in that: The feedwater pump turbine steam source switching system for a thermal power unit further comprises: a drain unit connected to the auxiliary steam header (6) and used for discharging mixed drain in the auxiliary steam header (6).

3. The feedwater pump steam turbine steam source switching system for a thermal power unit according to claim 2, characterized in that: The drain unit comprises: a drain pipe and a drain electric valve (11); One end of the drain pipe is connected to the drain outlet of the auxiliary steam header (6), and the other end is connected to a drain recovery device, and the mixed drain is discharged to the drain recovery device through the drain pipe; The drain electric valve (11) is arranged on the drain pipe and is used to control the flow state of the mixed drain in the drain pipe.

4. The feedwater pump steam turbine steam source switching system for a thermal power unit according to claim 1, characterized in that: The steam source switching system for the feedwater pump turbine of the thermal power unit further comprises: an auxiliary steam unit connected to the auxiliary steam header (6) and used for delivering the mixed extraction steam to the steam-using equipment.

5. The feedwater pump steam turbine steam source switching system for a thermal power unit according to claim 4, characterized in that: The auxiliary steam unit comprises: an auxiliary steam pipeline and an auxiliary steam electric valve (12); One end of the auxiliary steam pipeline is connected to the auxiliary steam header (6), and the other end is connected to the steam-consuming equipment, and the mixed extraction steam is transported to the steam-consuming equipment through the auxiliary steam pipeline; The auxiliary steam electric valve (12) is arranged on the auxiliary steam pipeline and is used to control the flow state of the mixed extraction steam in the auxiliary steam pipeline.

6. The feedwater pump steam turbine steam source switching system for a thermal power unit according to claim 1, characterized in that: The feedwater pump steam turbine steam source switching system of the thermal power unit further comprises: a mixing regulating valve (8) arranged on a pipeline between the auxiliary steam header (6) and the feedwater pump steam turbine (3) and used for regulating the flow of mixed extraction steam entering the feedwater pump steam turbine (3).

7. The feedwater pump steam turbine steam source switching system for a thermal power unit according to claim 1, characterized in that: The low-pressure steam extraction main unit (13) comprises: a low-pressure steam extraction main pipeline, a first check valve (1) and a first regulating valve (2); One end of the low-pressure steam extraction main pipeline is connected to the low-pressure steam extraction supply device, and the other end is connected to the feedwater pump steam turbine (3), and the low-pressure steam extraction is transported to the feedwater pump steam turbine (3) through the low-pressure steam extraction main pipeline; The first check valve (1) is arranged on the low-pressure steam extraction main pipeline and is used to control the flow direction of the low-pressure steam extraction in the low-pressure steam extraction main pipeline; The first regulating valve (2) is arranged on the low-pressure steam extraction main pipeline, and is used to regulate the steam entering the supply The flow rate of low-pressure extraction steam from the pump-turbine (3).

8. The feedwater pump steam turbine steam source switching system for a thermal power unit according to claim 1, characterized in that: The low-pressure steam extraction sub-unit (14) comprises: a low-pressure steam extraction sub-pipeline, a second check valve (4) and a second regulating valve (5); One end of the low-pressure steam extraction sub-pipeline is connected to a low-pressure steam extraction supply device, and the other end is connected to the auxiliary steam header (6), and the low-pressure steam extraction is transported to the auxiliary steam header (6) through the low-pressure steam extraction sub-pipeline; The second check valve (4) is arranged on the low-pressure steam extraction sub-pipeline and is used to control the flow direction of the low-pressure steam extraction in the low-pressure steam extraction sub-pipeline; The second regulating valve (5) is arranged on the low-pressure steam extraction sub-pipeline and is used to adjust the flow rate of the low-pressure steam extraction entering the auxiliary steam header (6).

9. The feedwater pump steam turbine steam source switching system for a thermal power unit according to claim 1, characterized in that: The cold re-extraction steam main unit (15) comprises: a cold re-extraction steam main pipeline and a third regulating valve (7); One end of the cold re-extraction steam main pipeline is connected to the cold re-extraction steam supply device, and the other end is connected to the auxiliary steam header (6), and the cold re-extraction steam is transported to the auxiliary steam header (6) through the cold re-extraction steam main pipeline; The third regulating valve (7) is arranged on the cold re-extraction steam main pipeline and is used for roughly adjusting the flow rate of the cold re-extraction steam entering the auxiliary steam header (6).

10. The feedwater pump steam turbine steam source switching system for a thermal power unit according to claim 1, characterized in that: The cold re-extraction sub-unit (16) comprises: a cold re-extraction sub-pipeline, a third check valve (9) and a fourth regulating valve (10); One end of the cold re-extraction steam sub-pipeline is connected to the cold re-extraction steam supply device, and the other end is connected to the auxiliary steam header (6), and the cold re-extraction steam is transported to the auxiliary steam header (6) through the cold re-extraction steam sub-pipeline; The third check valve (9) is arranged on the cold re-extraction steam sub-pipeline and is used to control the flow direction of the cold re-extraction steam in the cold re-extraction steam sub-pipeline; The fourth regulating valve (10) is arranged on the cold re-extraction steam sub-pipeline and is used for finely adjusting the flow rate of the cold re-extraction steam entering the auxiliary steam header (6).

Images