A kind of power plant shutdown open cooling water system

Abstract

The utility model belongs to the technical field of power plant auxiliary machine cooling water system, especially relates to a thermal power plant shutdown open cooling water system. The system of the utility model includes open type circulating cooling water pipeline, open type circulating cooling water pipeline is connected between circulating water supply pipeline and circulating water return pipeline, and the open type circulating cooling water pipeline is connected with electric water filter and a plurality of closed circulating cooling water heat exchanger, further includes shutdown cooling water supply pipeline, shutdown cooling water supply pipeline is connected to circulating water supply pipeline, and the shutdown cooling water supply pipeline is installed with shutdown cooling water pump, and the circulating water supply pipeline is installed with circulating water pump, and the power of shutdown cooling water pump is less than the power of circulating water pump, the electric water filter and closed circulating cooling water heat exchanger are located in main plant house, and the connecting point of shutdown cooling water supply pipeline and circulating water supply pipeline is located outside main plant house. The utility model provides a thermal power plant shutdown open cooling water system, reduces pipeline length and valve quantity, thereby reduces initial investment, and under the background that peak regulation unit frequently starts and stops, the system is simple, and power plant operation maintenance cost is greatly reduced.

Description

Technical Field

[0001] This utility model belongs to the technical field of cooling water systems for auxiliary equipment in power plants, and specifically relates to a cooling water system for power plant shutdown and startup. Background Technology

[0002] In thermal power plants (including coal-fired units and gas-steam combined cycle units), the shutdown cooling water system is a key auxiliary system used to safely and efficiently reduce equipment temperature after the unit is shut down. Its main function is to remove residual heat after shutdown, prevent equipment damage caused by high temperature or thermal stress, and improve the flexibility of unit restart.

[0003] Power plant auxiliary equipment cooling water systems are divided into open-loop cooling water systems and closed-loop cooling water systems. Open-loop cooling water systems are generally connected from the circulating water system and are used to cool auxiliary equipment that does not have high requirements for water quality and to cool closed-loop cooling water heat exchangers; closed-loop cooling water systems are used to cool auxiliary equipment that has high requirements for water quality.

[0004] During normal operation, the cooling water source of the open cooling water system comes from the circulating water pipe. After being filtered by the electric water filter, it enters the closed-loop circulating cooling water heat exchanger as low-temperature water. It exchanges heat with the high-temperature water after the closed cooling water system has cooled the equipment. Then, the open cooling water that has absorbed heat returns to the circulating water system, while the cooled closed cooling water continues to cool the auxiliary equipment, thus completing the circulation of open and closed cooling water.

[0005] like Figure 2 As shown, when the unit is first shut down, only some auxiliary equipment (such as generators, bearings, and lubrication systems) requires continuous cooling to prevent high temperatures from causing lubricant deterioration or bearing wear. At this time, the closed-loop cooling water heat exchanger requires only a small amount of heat exchange. The cooling water source can be switched from circulating water to shutdown cooling water. This involves opening shutdown cooling water pump 14 and the eighth electric butterfly valve 15, and closing the second electric butterfly valve 3. The shutdown cooling water pressurized by shutdown cooling water pump 14 replaces the circulating water pressurized by circulating water pump 1 during normal operation to cool the closed-loop cooling water heat exchanger, and then returns to the cooling tower pool. Since the power and head of shutdown cooling water pump 14 are smaller than those of circulating water pump 1, a significant amount of plant power can be saved. However, the shutdown cooling water pump 14 is usually located in the plant area, while the interface between the shutdown cooling water and the start-up cooling water pipeline is in the main plant area. It is necessary to set up a water supply line and a return line from the plant area to the main plant area. The length of the pipeline on one side is relatively long (about several hundred meters), and electric butterfly valves need to be installed on both the water supply and return lines, which increases the initial investment and the intensity of operation and maintenance. Figure 2 In the middle, the shutdown cooling water supply pipeline is connected to the shutdown cooling water pump and the eighth electric butterfly valve 15, and the shutdown cooling water return pipeline is connected to the ninth electric butterfly valve 16. Utility Model Content

[0006] In order to solve the above-mentioned problems in the existing technology, the purpose of this utility model is to provide a cooling water system for power plant shutdown, which reduces pipeline length and number of valves, thereby reducing initial investment. In the context of frequent start-up and shutdown of peak-shaving units, the system is simple and greatly reduces the operation and maintenance costs of power plants.

[0007] The technical solution adopted in this utility model is as follows: A shutdown cooling water system for a thermal power plant includes an open-loop circulating cooling water pipeline connected between a circulating water supply pipeline and a circulating water return pipeline. An electric water filter and several closed-loop circulating cooling water heat exchangers are connected to the open-loop circulating cooling water pipeline. The system also includes a shutdown cooling water supply pipeline connected to the circulating water supply pipeline. A shutdown cooling water pump is installed on the shutdown cooling water supply pipeline, and a circulating water pump is installed on the circulating water supply pipeline. The power of the shutdown cooling water pump is less than that of the circulating water pump. The electric water filter and the closed-loop circulating cooling water heat exchangers are located inside the main plant building, while the connection point between the shutdown cooling water supply pipeline and the circulating water supply pipeline is located outside the main plant building.

[0008] This invention, based on the original technical solution, eliminates the shutdown cooling water return pipeline and its electric butterfly valve, as well as the electric butterfly valve on the shutdown cooling water supply pipeline. The original shutdown cooling water interface in the main plant building is moved to the circulating water supply pipeline at the outlet of the circulating water pump; this interface is much closer to the shutdown cooling water pump (less than a few tens of meters). The circulating water supply pipeline serves as the shutdown cooling water container, supplying shutdown cooling water to the closed-loop circulating cooling water heat exchanger during shutdown. After cooling, the water returns to the cooling tower via a large-diameter circulating return pipeline.

[0009] During normal operation, the circulating water pump is turned on to supply water to the open cooling water system, cooling the closed-loop circulating cooling water heat exchanger. When shutting down, the electric butterfly valves on the circulating water pump and the circulating water supply pipeline are closed, and the shutdown cooling water pump is turned on to supply water to the open cooling water system, cooling the closed-loop circulating cooling water heat exchanger. After cooling, the shutdown cooling water is transported to the cooling tower through a large-diameter circulating return water pipeline.

[0010] This invention directly delivers shutdown cooling water to the cooling tower via a large-diameter circulating return water pipeline after unit shutdown, thus eliminating the need for the shutdown cooling water return water pipeline and its associated electric butterfly valve. The original shutdown cooling water inlet in the main plant building is relocated to the circulating water supply pipeline at the outlet of the circulating water pump. This inlet is closer to the shutdown cooling water pump, reducing pipeline length. Furthermore, water is supplied via the circulating water supply pipeline during normal operation or via the shutdown cooling water supply pipeline during shutdown, with the cooling water flow controlled by an electric butterfly valve on the open circulating cooling water pipeline, eliminating the need for an electric butterfly valve on the shutdown cooling water supply pipeline. This invention reduces pipeline length and the number of valves by changing the system inlet method, reducing initial investment. Moreover, given the frequent start-ups and shutdowns of peak-shaving units, the system is simple and significantly reduces power plant operation and maintenance costs.

[0011] As a preferred embodiment of this utility model, the two ends of the circulating water supply pipeline are respectively connected to the condenser and the forebay of the circulating water pump house, and the two ends of the circulating water return pipeline are connected to the condenser and the cooling tower water pool, which is more suitable for thermal power plants that adopt a secondary circulation cooling scheme.

[0012] As a preferred embodiment of this utility model, one end of the shutdown cooling water supply pipeline is connected to the forebay of the circulating water pump house, and the forebay of the circulating water pump house is connected to the cooling tower water pool through a return water ditch. The water source for the shutdown cooling water supply pipeline is taken from the cooling tower water pool from the forebay of the circulating water pump house. When the system is shut down, the shutdown cooling water is supplied to the operating cooling water system to cool the closed-loop circulating cooling water heat exchanger. After cooling, the shutdown cooling water is transported to the cooling tower through a large-diameter circulating return water pipeline to achieve water circulation.

[0013] As a preferred embodiment of this utility model, a first electric butterfly valve is also connected to the circulating water supply pipeline. One end of the shutdown cooling water supply pipeline and one end of the open circulating cooling water pipeline are both connected between the circulating water pump and the first electric butterfly valve on the circulating water supply pipeline. When the system is shut down, the circulating water pump and the first electric butterfly valve are closed, and the shutdown cooling water pump is turned on, supplying water from the shutdown cooling water to the open cooling water system.

[0014] As a preferred embodiment of this utility model, a second electric butterfly valve and a third electric butterfly valve are connected to the open circulating cooling water pipeline. The second electric butterfly valve is located at the inlet end of the electric water filter, and the third electric butterfly valve is located at the outlet end of the electric water filter.

[0015] As a preferred embodiment of this utility model, the number of closed-loop cooling water heat exchangers is two, namely a first closed-loop cooling water heat exchanger and a second closed-loop cooling water heat exchanger, which are connected in parallel.

[0016] After being filtered by an electric water filter, the cooling water enters the closed-loop cooling water heat exchanger as low-temperature water. It exchanges heat with the high-temperature water after the closed-loop cooling water system has cooled the equipment. The heat-absorbing open-loop cooling water then returns to the circulating water system, while the cooled closed-loop cooling water continues to cool the auxiliary equipment, thus completing the circulation of open-loop and closed-loop cooling water.

[0017] As a preferred embodiment of this utility model, the inlet end of the first closed-loop cooling water heat exchanger is connected to a fourth electric butterfly valve, and the outlet end of the first closed-loop cooling water heat exchanger is connected to a first adjustable electric butterfly valve.

[0018] As a preferred embodiment of this utility model, the inlet end of the second closed-loop cooling water heat exchanger is connected to a fifth electric butterfly valve, and the outlet end of the first closed-loop cooling water heat exchanger is connected to a second adjustable electric butterfly valve.

[0019] As a preferred embodiment of this utility model, a sixth electric butterfly valve is also connected to the open circulating cooling water pipeline, and the sixth electric butterfly valve is located in a section of the open circulating cooling water pipeline near the circulating water return pipeline.

[0020] As a preferred embodiment of this utility model, a seventh electric butterfly valve is connected to the circulating water return pipeline.

[0021] The beneficial effects of this utility model are as follows: This invention directly delivers shutdown cooling water to the cooling tower via a large-diameter circulating return water pipeline after unit shutdown, thus eliminating the need for the shutdown cooling water return water pipeline and its associated electric butterfly valve. The original shutdown cooling water inlet in the main plant building is relocated to the circulating water supply pipeline at the outlet of the circulating water pump. This inlet is closer to the shutdown cooling water pump, reducing pipeline length. Furthermore, water is supplied via the circulating water supply pipeline during normal operation or via the shutdown cooling water supply pipeline during shutdown, with the cooling water flow controlled by an electric butterfly valve on the open circulating cooling water pipeline, eliminating the need for an electric butterfly valve on the shutdown cooling water supply pipeline. This invention reduces pipeline length and the number of valves by changing the system inlet method, reducing initial investment. Moreover, given the frequent start-ups and shutdowns of peak-shaving units, the system is simple and significantly reduces power plant operation and maintenance costs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of a traditional open-loop cooling water system.

[0023] In the diagram: 1-Circulating water pump; 2-First electric butterfly valve; 3-Second electric butterfly valve; 4-Electric water filter; 5-Third electric butterfly valve; 6-Fourth electric butterfly valve; 7-First closed-loop circulating cooling water heat exchanger; 8-First adjustable electric butterfly valve; 9-Fifth electric butterfly valve; 10-Second closed-loop circulating cooling water heat exchanger; 11-Second adjustable electric butterfly valve; 12-Sixth electric butterfly valve; 13-Seventh electric butterfly valve; 14-Stop cooling water pump; 15-Eighth electric butterfly valve; 16-Ninth electric butterfly valve. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0026] like Figure 1 As shown, the power plant shutdown cooling water system of this embodiment includes an open circulating cooling water pipeline connected between the circulating water supply pipeline and the circulating water return pipeline. An electric water filter 4 and several closed circulating cooling water heat exchangers are connected to the open circulating cooling water pipeline. It also includes a shutdown cooling water supply pipeline connected to the circulating water supply pipeline. A shutdown cooling water pump 14 is installed on the shutdown cooling water supply pipeline, and a circulating water pump 1 is installed on the circulating water supply pipeline. The power of the shutdown cooling water pump 14 is less than that of the circulating water pump 1. The electric water filter 4 and the closed circulating cooling water heat exchangers are located inside the main plant building, while the connection point between the shutdown cooling water supply pipeline and the circulating water supply pipeline is located outside the main plant building.

[0027] Based on the original technical solution, this utility model eliminates the shutdown cooling water return pipeline and its electric butterfly valve, as well as the electric butterfly valve on the shutdown cooling water supply pipeline. The shutdown cooling water interface, originally located in the main plant building, is moved to the circulating water supply pipeline at the outlet of circulating water pump 1. This interface is much closer to the shutdown cooling water pump 14 (less than a few tens of meters away). The circulating water supply pipeline is used as a shutdown cooling water container, supplying shutdown cooling water to the closed-loop circulating cooling water heat exchanger during shutdown. After cooling, the water returns to the cooling tower via a large-diameter circulating return pipeline.

[0028] During normal operation, circulating water pump 1 is turned on to supply water to the open cooling water system, cooling the closed-loop circulating cooling water heat exchanger. During shutdown, circulating water pump 1 and the electric butterfly valve on the circulating water supply pipeline are closed, and shutdown cooling water pump 14 is turned on to supply water to the open cooling water system, cooling the closed-loop circulating cooling water heat exchanger. After cooling, the shutdown cooling water is transported to the cooling tower through a large-diameter circulating return water pipeline.

[0029] This invention directly delivers shutdown cooling water to the cooling tower via a large-diameter circulating return water pipeline after shutdown, thus eliminating the need for the shutdown cooling water return water pipeline and its associated electric butterfly valve. The original shutdown cooling water interface in the main plant building is relocated to the circulating water supply pipeline at the outlet of circulating water pump 1. This interface is closer to the shutdown cooling water pump 14, reducing pipeline length. Furthermore, water is supplied via the circulating water supply pipeline during normal operation or during shutdown via the shutdown cooling water supply pipeline, with the cooling water flow controlled by an electric butterfly valve on the open circulating cooling water pipeline, eliminating the need for an electric butterfly valve on the shutdown cooling water supply pipeline. This invention reduces pipeline length and the number of valves by changing the system inlet method, reducing initial investment. Moreover, given the frequent start-ups and shutdowns of peak-shaving units, the system is simple and significantly reduces power plant operation and maintenance costs.

[0030] The circulating water supply pipeline connects to the condenser and the circulating water pump house forebay at both ends, while the circulating water return pipeline connects to the condenser and the cooling tower water pool at both ends, making it more suitable for thermal power plants employing a secondary circulation cooling scheme. One end of the shutdown cooling water supply pipeline connects to the circulating water pump house forebay, which is connected to the cooling tower water pool via a return water ditch. The water source for the shutdown cooling water supply pipeline is taken from the cooling tower water pool from the circulating water pump house forebay. During shutdown, the shutdown cooling water supplies water to the operating cooling water system to cool the closed-loop circulating cooling water heat exchanger. After cooling, the shutdown cooling water is transported to the cooling tower through a large-diameter circulating return water pipeline, achieving water circulation.

[0031] The circulating water supply pipeline is also connected to a first electric butterfly valve 2. One end of the shutdown cooling water supply pipeline and one end of the open circulating cooling water pipeline are both connected between the circulating water pump 1 and the first electric butterfly valve 2 on the circulating water supply pipeline. When the system is shut down, the circulating water pump 1 and the first electric butterfly valve 2 are closed, and the shutdown cooling water pump 14 is turned on, so that the shutdown cooling water supplies water to the open cooling water system.

[0032] The open circulating cooling water pipeline is connected to a second electric butterfly valve 3 and a third electric butterfly valve 5. The second electric butterfly valve 3 is located at the inlet end of the electric water filter 4, and the third electric butterfly valve 5 is located at the outlet end of the electric water filter 4.

[0033] Specifically, there are two closed-loop cooling water heat exchangers, namely a first closed-loop cooling water heat exchanger 7 and a second closed-loop cooling water heat exchanger 10, which are connected in parallel.

[0034] After being filtered by the electric water filter 4, the cooling water enters the closed-loop cooling water heat exchanger as low-temperature water, where it exchanges heat with the high-temperature water after the closed-loop cooling water system has cooled the equipment. The heat-absorbing open-loop cooling water then returns to the circulating water system, while the cooled closed-loop cooling water continues to cool the auxiliary equipment, thus completing the circulation of open-loop and closed-loop cooling water.

[0035] The inlet end of the first closed-loop cooling water heat exchanger 7 is connected to a fourth electric butterfly valve 6, and the outlet end of the first closed-loop cooling water heat exchanger 7 is connected to a first adjustable electric butterfly valve 8.

[0036] The inlet end of the second closed-loop cooling water heat exchanger 10 is connected to a fifth electric butterfly valve 9, and the outlet end of the first closed-loop cooling water heat exchanger 7 is connected to a second adjustable electric butterfly valve 11.

[0037] The open circulating cooling water pipeline is also connected to a sixth electric butterfly valve 12, which is located in a section of the open circulating cooling water pipeline near the circulating water return pipeline.

[0038] The circulating water return pipeline is connected to a seventh electric butterfly valve 13.

[0039] This utility model is not limited to the above-mentioned optional embodiments. Anyone can derive other forms of products under the guidance of this utility model. However, regardless of any changes made in its shape or structure, any technical solution that falls within the scope of the claims of this utility model shall be protected by this utility model.

Claims

1. A cooling water start-up system for power plant shutdown, characterized in that: It includes an open circulating cooling water pipeline, which is connected between the circulating water supply pipeline and the circulating water return pipeline. An electric water filter (4) and several closed circulating cooling water heat exchangers are connected to the open circulating cooling water pipeline. It also includes a shutdown cooling water supply pipeline, which is connected to the circulating water supply pipeline. A shutdown cooling water pump (14) is installed on the shutdown cooling water supply pipeline, and a circulating water pump (1) is installed on the circulating water supply pipeline. The power of the shutdown cooling water pump (14) is smaller than that of the circulating water pump (1). The electric water filter (4) and the closed circulating cooling water heat exchangers are located inside the main plant building, and the connection point between the shutdown cooling water supply pipeline and the circulating water supply pipeline is located outside the main plant building.

2. The cooling water start-up system for power plant shutdown according to claim 1, characterized in that: The circulating water supply pipeline is connected to the condenser and the circulating water pump room forebay at both ends, and the circulating water return pipeline is connected to the condenser and the cooling tower water pool at both ends.

3. A cooling water start-up system for power plant shutdown as described in claim 2, characterized in that: One end of the shutdown cooling water supply pipeline is connected to the forebay of the circulating water pump house, and the forebay of the circulating water pump house is connected to the cooling tower water pool through a return water ditch.

4. A cooling water start-up system for power plant shutdown as described in claim 1, characterized in that: The circulating water supply pipeline is also connected to a first electric butterfly valve (2). One end of the shutdown cooling water supply pipeline and one end of the open circulating cooling water pipeline are both connected between the circulating water pump (1) and the first electric butterfly valve (2) on the circulating water supply pipeline.

5. A cooling water start-up system for power plant shutdown as described in claim 1, characterized in that: The open circulating cooling water pipeline is connected to a second electric butterfly valve (3) and a third electric butterfly valve (5). The second electric butterfly valve (3) is located at the inlet end of the electric water filter (4), and the third electric butterfly valve (5) is located at the outlet end of the electric water filter (4).

6. A cooling water start-up system for power plant shutdown as described in claim 1, characterized in that: The number of closed-loop cooling water heat exchangers is two, namely a first closed-loop cooling water heat exchanger (7) and a second closed-loop cooling water heat exchanger (10), which are connected in parallel.

7. A cooling water start-up system for power plant shutdown as described in claim 6, characterized in that: The inlet end of the first closed-loop cooling water heat exchanger (7) is connected to a fourth electric butterfly valve (6), and the outlet end of the first closed-loop cooling water heat exchanger (7) is connected to a first adjustable electric butterfly valve (8).

8. A cooling water start-up system for power plant shutdown as described in claim 6, characterized in that: The inlet end of the second closed-loop cooling water heat exchanger (10) is connected to a fifth electric butterfly valve (9), and the outlet end of the first closed-loop cooling water heat exchanger (7) is connected to a second adjustable electric butterfly valve (11).

9. A cooling water start-up system for power plant shutdown as described in claim 1, characterized in that: The open circulating cooling water pipeline is also connected to a sixth electric butterfly valve (12), which is located in a section of the open circulating cooling water pipeline near the circulating water return pipeline.

10. A cooling water start-up system for power plant shutdown according to claim 1, characterized in that: The circulating water return pipeline is connected to a seventh electric butterfly valve (13).

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