A starting system and method based on the synergistic effect of double reduction and double exhaust of cold section

Abstract

This invention belongs to the field of thermal power generation technology, specifically relating to a startup system and method based on the synergistic effect of dual desuperheating and dual exhaust steam in the cold section. The invention establishes a first pair of air exhaust pipes and a second pair of air exhaust pipes before and after the low-temperature reheat steam pipeline (cold section) to the auxiliary steam desuperheating and pressure reducing device (dual desuperheating). Through the coordinated control of the first and second pairs of air exhaust (dual exhaust), both rapid startup of the unit without a start-up boiler and stable regulation of boiler-side pressure during startup can be achieved. This method significantly improves the unit startup speed while also warming up the auxiliary steam pipelines and avoiding damage to pipelines and supports due to excessive exhaust steam reaction force in the air exhaust pipes, effectively reducing the energy consumption and cost of unit startup.

Description

Technical Field

[0001] This invention belongs to the field of thermal power generation technology, specifically relating to a start-up system and method based on the synergistic effect of dual reduction and dual exhaust steam in the cold section. Background Technology

[0002] During the startup process of a conventional thermal power plant or a gas-fired combined cycle power plant, the first unit to be started usually requires a startup boiler (or purchased auxiliary steam) to provide auxiliary steam for the turbine shaft seals, enabling the unit to establish a vacuum. This allows the bypass system to discharge the initial steam into the condenser to stabilize and regulate the boiler-side pressure.

[0003] However, since the boiler and its supporting systems must be started before the unit can be started, the start-up time is extended and the initial investment, operation and maintenance costs are increased.

[0004] In addition, the boilers used for startup are usually small boilers, which have lower efficiency, higher energy consumption, and are relatively more difficult to control pollutant emissions.

[0005] Therefore, there is an urgent need for a start-up system and method that does not require a start-up boiler, can flexibly and stably adjust the boiler-side pressure during the initial start-up phase, and also takes into account pipe warming, in order to solve the above problems. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a start-up system and method based on the synergistic effect of dual reduction and dual exhaust steam in the cold section. The system utilizes the cold section steam of the main unit to achieve safe and economical start-up of the unit through dual exhaust steam synergistic regulation, which can improve the start-up speed of the unit, reduce the start-up energy consumption and cost of the unit, and at the same time take into account the warm-up of the pipeline.

[0007] To achieve the aforementioned objective, the present invention provides a start-up system based on the synergistic effect of dual reduction and dual exhaust in the cold section, comprising: The low-temperature reheat steam pipeline is connected to the first auxiliary steam pipeline; the first auxiliary steam pipeline is connected to the second auxiliary steam pipeline; the second auxiliary steam pipeline is connected to the auxiliary steam header pipeline; the first auxiliary steam pipeline is connected to the first air exhaust pipeline; the second auxiliary steam pipeline is connected to the second air exhaust pipeline; the first air exhaust pipeline and the second air exhaust pipeline are used to coordinately control and regulate the pressure on the boiler side by venting steam into the air during the startup process, thereby realizing the startup of the boiler unit without a start-up furnace and warming up the auxiliary steam header pipeline.

[0008] Preferably, it also includes an auxiliary steam desuperheater and pressure reducer; the auxiliary steam desuperheater and pressure reducer is installed at the connection between the first auxiliary steam pipeline and the second auxiliary steam pipeline.

[0009] Preferably, the inlet end of the first pair of air exhaust pipes is connected to the auxiliary steam double reduction pipe, the outlet end of the first pair of air exhaust pipes is open to the atmosphere, and a silencer is installed at the end of the outlet end. A first isolation valve, a pressure regulating valve and a second isolation valve are connected in series on the first pair of air exhaust pipes; a first condensate drain pipe is installed after the second isolation valve.

[0010] Preferably, the inlet end of the second pair of air exhaust pipes is connected to the auxiliary steam double reduction pipe, the outlet end of the second pair of air exhaust pipes is open to the atmosphere, a second silencer is installed at the end of the second pair of air exhaust pipes, and a second isolation valve, a shut-off valve and a second isolation valve are connected in series on the second pair of air exhaust pipes; a drain pipe is installed after the second isolation valve.

[0011] Preferably, the auxiliary steam header is connected to the steam supply pipeline of the turbine shaft sealing system.

[0012] Preferably, during startup, to prevent the exhaust steam reaction force from damaging the pipe support, the second pair of air exhaust pipes should be used first for air exhaust, and the first pair of air exhaust pipes should use intermittent air exhaust to assist the second pair of air exhaust pipes in regulating the pressure on the boiler side.

[0013] Preferably, the method of using the starting system based on the synergistic effect of dual reduction and dual exhaust in the cold section includes the following steps: 1) Pressure building phase After the boiler is ignited, the third isolation valve, the shut-off valve and the fourth isolation valve on the second pair of air exhaust pipeline are all in the open state. The isolation valve after the auxiliary steam double reduction and the isolation valve from the cold section to the auxiliary steam double reduction are also in the open state. Steam is delivered from the low-temperature reheat steam pipeline to the auxiliary steam desuperheater and pressure reducer to reduce steam parameters to the auxiliary steam parameters, and then delivered to the auxiliary steam header pipeline to warm up the auxiliary steam header pipeline. The second air vent pipe (after double reduction) is used to vent steam to the air and regulate the pressure on the boiler side. 2) Coordinated Regulation Phase As boiler-side steam parameters increase, the pressure in the low-temperature reheat steam pipeline rises. When the exhaust valve of the second pair of air exhaust pipes 200 is fully opened, it is still unable to suppress the pressure rise in the pipelines before the double-reduction steam reduction and on the boiler side. The first isolation valve on the first pair of air exhaust pipes opens automatically, and the first pair of air exhaust pipes cooperates with the second pair of air exhaust pipes to relieve pressure. 3) Switching Phase When the steam parameters of the low-temperature reheat steam pipeline meet the requirements for shaft seal steam supply, the first pair of air exhaust pipes and the second pair of air exhaust pipes are closed. The steam in the pipeline before the double desuperheating and depressurization of the cold section to the auxiliary steam is desuperheated and depressurized through the desuperheating and depressurization device of the cold section to the auxiliary steam. The steam is then supplied to the shaft seal through the pipeline after the double desuperheating and depressurization of the cold section to the auxiliary steam and the auxiliary steam main pipe to establish unit vacuum.

[0014] The beneficial effects of this invention are reflected in: (1) The system provided by the present invention leads out the first pair of air exhaust pipes and the second pair of air exhaust pipes before and after the cold section to the auxiliary steam double reduction. Through the synergistic effect of the double exhaust, it not only satisfies the stable regulation of the boiler side pressure during the start-up process, thereby realizing the start-up of the unit without a start-up boiler, but also completes the warm-up of the auxiliary steam pipes. At the same time, it effectively avoids the problem of excessive exhaust steam reaction force damaging the pipes and supports, significantly improving the start-up speed of the unit and reducing the energy consumption and cost of the unit start-up.

[0015] (2) The system provided by the present invention eliminates the need to start the boiler: it makes full use of the steam generated by the unit itself, saving investment, operation and maintenance costs and simplifying the system.

[0016] (3) The system pressure control provided by the present invention is more stable: through the two-level collaborative strategy of "main adjustment of the pipeline after double reduction + auxiliary adjustment of the pipeline before double reduction", the pressure regulation range is expanded, which can adapt to the wide range of changes in boiler steam production from zero to rated value during the start-up process.

[0017] (4) The system provided by the present invention has high safety: most of the exhaust tasks are assigned to the second pair of air exhaust pipes with lower parameters, and the high-pressure first pair of air exhaust pipes are only activated when necessary, and strict valve opening control is provided to effectively reduce the risk of excessive exhaust reaction force damaging the pipes and supports.

[0018] (5) The system provided by the present invention takes into account both pipe warming: the exhaust pipe after double reduction is used as a pipe warming channel, the process is reasonable and the start-up time is shortened. Attached Figure Description

[0019] Figure 1 This is a system framework diagram of the present invention.

[0020] Figure labels and descriptions: 1. First isolation valve; 2. Pressure regulating valve; 3. Second isolation valve; 4. First silencer; 5. Third isolation valve; 6. Isolation valve; 7. Fourth isolation valve; 8. Second silencer; 100. First exhaust pipe; 101. First drain pipe; 200. Second exhaust pipe for air; 102. Second drain pipe; 300. Pipeline from the cold section to the auxiliary steam before the double pressure reduction; 301. Isolation valve from the cold section to the auxiliary steam before the double pressure reduction; 302. Cold section to the auxiliary steam desuperheater and pressure reducer; 303. Isolation valve from the cold section to the auxiliary steam after the double pressure reduction; 400. Pipeline from the cold section to the auxiliary steam after double reduction; 500, Low-temperature reheat steam pipeline; 600, Auxiliary steam main pipeline. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 like Figure 1 As shown, this invention provides a start-up system and operating method based on the synergistic effect of dual reduction and dual exhaust steam in the cold section. It includes: The system sequentially forms a series of low-temperature reheat steam pipeline 500, a pipeline 300 from the cold section to the auxiliary steam before the double reduction, a pipeline 400 from the cold section to the auxiliary steam after the double reduction, and an auxiliary steam main pipeline 600.

[0023] The first auxiliary steam pipeline 300 is connected to the second auxiliary steam pipeline 400; the second auxiliary steam pipeline 400 is connected to the auxiliary steam header pipeline 600; the first auxiliary steam pipeline 300 is connected to the first air exhaust pipeline 100; the second auxiliary steam pipeline 400 is connected to the second air exhaust pipeline 200; the first air exhaust pipeline 100 and the second air exhaust pipeline 200 are used to coordinately control and regulate the pressure on the boiler side during startup by exhausting steam into the air, thereby realizing the startup of the boiler unit without a start-up furnace, and warming up the auxiliary steam header pipeline 600.

[0024] In practical use, the first pair of air vent pipes 100 and the second pair of air vent pipes 200 are used to regulate and control the pressure on the boiler side during the boiler pressurization process. The first pair of air vent pipes 100 and the second pair of air vent pipes 200 function similarly to vent valves. When the boiler side pressure is detected to be too high, air is released through these two vent pipes to control the pressure and ensure production safety.

[0025] A cold section to auxiliary steam double reduction front isolation valve 301 is installed on the cold section to auxiliary steam double reduction front pipeline 300; a cold section to auxiliary steam double reduction rear isolation valve 303 is installed on the cold section to auxiliary steam double reduction rear pipeline 400; a cold section to auxiliary steam desuperheating and pressure reducing device 302 is installed at the connection between the cold section to auxiliary steam double reduction front pipeline 300 and the cold section to auxiliary steam double reduction rear pipeline 400.

[0026] The isolation valve 303 after the cold section to auxiliary steam double desuperheater and the isolation valve 301 before the cold section to auxiliary steam double desuperheater are used to isolate the cold section to auxiliary steam desuperheater and pressure reducer 302. In actual use, auxiliary steam is not always required in all operating conditions. For example, isolation is also required when 302 needs maintenance.

[0027] In practical applications, steam can flow out from the low-temperature reheat steam pipeline 500, pass through the cold section to the auxiliary steam double reduction pipeline 300 and the cold section to the auxiliary steam double reduction pipeline 400, and then be transported to the auxiliary steam main pipeline 600 to warm up the auxiliary steam main pipeline 600.

[0028] That is, the steam in the auxiliary steam header 600 comes from the low-temperature reheat steam pipeline 500. Since the steam pressure, temperature and other parameters in the low-temperature reheat steam pipeline 500 are relatively high, it needs to be reduced to the auxiliary steam parameters through the cold section to the auxiliary steam desuperheater and pressure reducer 302 so that the steam can be used.

[0029] The first pair of air exhaust pipes 100 are connected in series with a first isolation valve 1, a pressure regulating valve 2, a second isolation valve 3 and a silencer 4, and a drain pipe 101 is installed after the second isolation valve 3.

[0030] The first isolation valve 1 is used to control the start and stop of the first air exhaust pipe 100, the silencer 4 is used to silence the air during exhaust and reduce noise, and the pressure regulating valve 2 is used to control the exhaust back pressure.

[0031] A third isolation valve 5, a shut-off valve 6, a fourth isolation valve 7, and a second silencer 8 are connected in series on the second pair of air exhaust pipes 200. A condensate drain pipe 201 is installed after the fourth isolation valve 7.

[0032] Example 2 The unit's start-up process without a starter boiler is as follows: 1) Pressure building stage: After the boiler is ignited, the third isolation valve 5, the isolation valve 6 and the fourth isolation valve 7 on the second pair of air exhaust pipe 200 are all in the open state. The isolation valve 303 after the auxiliary steam double reduction and the isolation valve 301 from the cold section to the auxiliary steam double reduction are also in the open state. Steam from the low temperature reheat steam pipe 500 is de-heated and de-pressurized by the auxiliary steam desuperheater and pressure reducer 302 to reduce the steam parameters to the auxiliary steam parameters, and then it is delivered to the auxiliary steam header pipe 600 to warm up the auxiliary steam header pipe 600.

[0033] By utilizing the second air vent pipe 200 (after double reduction) for air venting, the pressure on the boiler side can be adjusted and controlled during the boiler pressurization process.

[0034] 2) Coordinated Regulation Stage: As boiler-side steam parameters increase, the pressure in the low-temperature reheat steam pipeline rises to 500. When the exhaust valve of the second pair of air exhaust pipes 200 is fully open but still cannot suppress the pressure rise of the pipe 300 before the double reduction, the first isolation valve 1 on the first pair of air exhaust pipes 100 automatically opens, and the first pair of air exhaust pipes 100 (before the double reduction) performs coordinated pressure relief on the second pair of air exhaust pipes 200 to ensure that the exhaust return force of the pipe is within the allowable range of the pipe support.

[0035] 3) Switching phase: When the steam parameters of the low-temperature reheat steam pipeline 500 meet the requirements for shaft seal steam supply, the air exhaust pipeline is gradually closed; that is, the first air exhaust pipeline 100 (before double reduction) and the second air exhaust pipeline 200 are closed; since the auxiliary steam header pipeline 600 is connected to the steam supply pipeline of the turbine shaft seal system, the cold section steam is de-cooled and de-pressurized through the cold section to the auxiliary steam de-cooling and de-pressurizing device 302, and then used for shaft seal steam supply through the auxiliary steam header pipeline 600, thereby establishing unit vacuum.

[0036] The specific process is as follows: the steam parameters of the low-temperature reheat steam pipeline 500 do not meet the requirements and the parameters are gradually increasing. At this time, the steam is regulated by the coordinated exhaust of the first pair of air exhaust pipelines 100 and the second pair of air exhaust pipelines 200. When the low-temperature reheat steam pipeline 500 meets the requirements, both the first isolation valve 1 and the second isolation valve 5 are closed. Steam flows from the low-temperature reheat steam pipeline 500 through the first auxiliary steam pipeline 300 and the second auxiliary steam pipeline 400 into the auxiliary steam header pipeline 600. The auxiliary steam header pipeline 600 is connected to the shaft seal steam supply pipeline. Opening the valve on the auxiliary steam header pipeline 600 that connects to the shaft seal steam supply pipeline allows steam to be supplied to the shaft seal via the auxiliary steam pipeline. Only after the shaft seal has steam can the unit establish a shaft seal. At this time, the vacuum pump must be turned on to establish a vacuum in the unit.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A starting system based on the synergistic effect of dual reduction and dual exhaust in the cold section, characterized in that, It includes a low-temperature reheat steam pipeline (500), which is connected to a first auxiliary steam pipeline (300); the first auxiliary steam pipeline (300) is connected to a second auxiliary steam pipeline (400); the second auxiliary steam pipeline (400) is connected to an auxiliary steam header pipeline (600); the first auxiliary steam pipeline (300) is connected to a first air exhaust pipeline (100); the second auxiliary steam pipeline (400) is connected to a second air exhaust pipeline (200); the first air exhaust pipeline (100) and the second air exhaust pipeline (200) are used to coordinately control and regulate the pressure on the boiler side by air exhaust during the start-up process, and to warm up the auxiliary steam header pipeline (600).

2. The starting system based on the synergistic effect of dual reduction and dual exhaust in the cold section according to claim 1, characterized in that, It also includes an auxiliary steam desuperheater and pressure reducer (302); the auxiliary steam desuperheater and pressure reducer (302) is installed at the connection between the first auxiliary steam pipeline (300) and the second auxiliary steam pipeline (400).

3. The starting system based on the synergistic effect of dual reduction and dual exhaust in the cold section according to claim 1, characterized in that, The inlet end of the first pair of air exhaust pipes (100) is connected to the auxiliary steam double reduction pipe (300). The outlet end of the first pair of air exhaust pipes (100) is open to the atmosphere, and a silencer (4) is installed at the end of the outlet end. The first pair of air exhaust pipes (100) is connected in series with a first isolation valve (1), a pressure regulating valve (2) and a second isolation valve (3). A first drain pipe (101) is installed after the second isolation valve (3).

4. The starting system based on the synergistic effect of dual reduction and dual exhaust in the cold section according to claim 1, characterized in that, The inlet end of the second pair of air exhaust pipes (200) is connected to the auxiliary steam double reduction pipe (400), the outlet end of the second pair of air exhaust pipes (200) is open to the atmosphere, a silencer (8) is installed at the end of the second pair of air exhaust pipes (200), and a third isolation valve (5), a shut-off valve (6) and a fourth isolation valve (7) are connected in series on the pipeline of the second pair of air exhaust pipes (200); a drain pipe (201) is installed after the fourth isolation valve (7).

5. A starting system based on the synergistic effect of dual reduction and dual exhaust in the cold section according to claim 1, characterized in that, The auxiliary steam header (600) is connected to the steam supply pipeline of the turbine shaft sealing system.

6. A starting system based on the synergistic effect of dual reduction and dual exhaust in the cold section according to claim 1, characterized in that, During startup, the second air exhaust pipe (200) exhausts steam into the air; the first air exhaust pipe (100) assists the second air exhaust pipe (200) in regulating the pressure on the boiler side by intermittently exhausting steam into the air.

7. The operation method of a start-up system based on the synergistic effect of dual reduction and dual exhaust steam in the cold section according to any one of claims 1-6, characterized in that, Includes the following steps: 1) Pressure building phase After the boiler is ignited, the third isolation valve (5), the shut-off valve (6) and the fourth isolation valve (7) on the second pair of air exhaust pipes (200) are all in the open state, and the isolation valve (303) after the auxiliary steam double reduction and the isolation valve (301) from the cold section to the auxiliary steam double reduction are also in the open state; Steam is delivered from the low-temperature reheat steam pipeline (500) through the auxiliary steam desuperheater and pressure reducer (302) to reduce the steam parameters to the auxiliary steam parameters, and then sent to the auxiliary steam header pipeline (600) to warm up the auxiliary steam header pipeline (600). The second air exhaust pipeline (200) is used to exhaust steam into the air and regulate and control the pressure on the boiler side. 2) Coordinated Regulation Phase As the boiler-side steam parameters increase, the pressure in the low-temperature reheat steam pipeline (500) rises. When the exhaust valve of the second pair of air exhaust pipeline (200) is fully open, it is still unable to suppress the pressure rise in the pipeline (300) from the cold section to the auxiliary steam double reduction section and the boiler side. The first isolation valve (1) on the first pair of air exhaust pipes (100) opens automatically, and the first pair of air exhaust pipes (100) cooperates with the second pair of air exhaust pipes (200) to relieve pressure. 3) Switching phase When the steam parameters of the low-temperature reheat steam pipeline (500) meet the requirements for shaft seal steam supply, the first pair of air exhaust pipelines (100) and the second pair of air exhaust pipelines (200) are closed. The steam in the cold section to auxiliary steam desuperheating and pressure reducing device (302) is desuperheated and pressure reduced in the cold section to auxiliary steam double desuperheating pipeline (300). The steam is then supplied to the shaft seal through the cold section to auxiliary steam double desuperheating pipeline (400) and the auxiliary steam main pipeline (600) to establish unit vacuum.

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