A circulating cooling system to prevent condenser inlet water temperature from being too cold

Abstract

The present invention discloses a circulating cooling system for preventing condenser inlet water from being overcooled, comprising a first condenser and a first cooling tower; the first cooling tower's water distribution area comprises a first inner zone and a first outer zone arranged inside and outside, the first inner zone being provided with a first inner zone water distribution gate; the cooling water outlet of the first condenser is connected to the first inner zone water distribution gate via a first return water pipe, the first return water pipe being further connected to a first return water override pipe, the first return water override pipe being connected to a water collection tank of the first cooling tower; the outlet channel of the first cooling tower is connected to the water supply pipe of the first condenser via a first circulating water pump; the first return water override pipe and the first return water pipe located behind the first return water override pipe are both provided with a first isolation valve. The circulating cooling system of the present invention can control the cooling tower outlet water temperature to be no less than 12°C, preventing the condenser pressure from being too low and posing a threat to the safe operation of the steam turbine.

Description

Technical Field

[0001] The invention relates to a circulating cooling system in a power plant or other production fields, and in particular to a circulating cooling system for preventing condenser inlet water from being overcooled. Background Art

[0002] A steam turbine is a key component of a thermal power plant, converting the thermal energy of steam into mechanical energy to drive a generator. Turbine exhaust pressure, also known as back pressure (kPa), refers to the absolute pressure behind the turbine's final blades. Condenser pressure refers to the absolute static pressure maintained within the steam passage 300mm above the first row of cooling tubes within the condenser casing. Generally, turbine back pressure can be considered equal to condenser pressure.

[0003] When the circulating water temperature entering the condenser decreases, the turbine back pressure decreases. The back pressure operating range of wet-cooled units is mostly between 3.0 kPa and 11.0 kPa. When the turbine back pressure is around 3.0 kPa, even if the back pressure is further reduced, the unit output cannot be increased. On the contrary, it may pose a threat to the safe operation of the turbine. However, when the condenser inlet water temperature is 12°C, the turbine back pressure is between 3.2 kPa and 3.5 kPa. Therefore, the design needs to consider controlling the condenser inlet water temperature above 12°C. In other words, in the circulating cooling system, the cooling tower outlet water temperature needs to be controlled to no less than 12°C.

[0004] In the existing technology, the main considerations are the freezing and antifreeze of cooling towers to prevent the civil structure and fillers of cooling towers from being damaged. The measures taken mainly include: 1. An antifreeze water spray pipe is set at the air inlet of the cooling tower. The hot water sprayed can melt the ice on the upper edge of the air inlet by the hot water to prevent a large amount of ice from forming; 2. Water distribution is carried out in different zones. In winter, the water density of the outer part of the tower filler is increased to prevent the filler from freezing; 3. A wind shield is set at the air inlet of the tower to reduce the entry of cold air and prevent the filler from freezing; 4. A bypass water pipe is set on the water inlet pipe of the cooling tower so that part or all of the circulating water does not go up the tower, but directly enters the collection pool to prevent the filler from freezing; 4. It is possible to consider stopping some towers in winter, and concentrating the circulating water into the running tower to increase the water density of the running tower.

[0005] The above measures are mainly used to prevent the cooling tower from freezing. Although they can also prevent the outlet water temperature from being too low, they lack a systematic design and cannot accurately achieve the goal of controlling the outlet water temperature of the cooling tower to not less than 12 degrees, making it difficult to ensure the safe operation of the turbine. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a circulating cooling system that prevents the condenser inlet water temperature from being too cold, which can solve the problem that the prior art cannot accurately control the cooling tower outlet water temperature to be no less than 12 degrees.

[0007] In order to achieve the above object, the present invention provides a circulating cooling system for preventing the condenser inlet water temperature from being overcooled, comprising a first condenser and a first cooling tower;

[0008] The water distribution area of ​​the first cooling tower includes a first inner area and a first outer area arranged inside and outside, and the first inner area is provided with a first inner area water distribution gate;

[0009] The cooling water outlet of the first condenser is connected to the first inner zone water distribution gate through a first return water pipe, and the first return water pipe is also connected to a first return water bypass pipe, and the first return water bypass pipe is connected to the water collection tank of the first cooling tower;

[0010] The outlet channel of the first cooling tower is connected to the water supply pipe of the first condenser through the first circulating water pump;

[0011] A first isolation valve is provided on the first return water bypass pipe and on the first return water pipe located at the rear side of the first return water bypass pipe.

[0012] As a preferred solution, a first closed return water channel is connected between the water outlet of the first cooling tower and the first circulating water pump.

[0013] As a preferred solution, it also includes a second condenser and a second cooling tower;

[0014] The water distribution area of ​​the second cooling tower includes a second inner area and a second outer area arranged inside and outside, and the second inner area is provided with a second inner area water distribution gate;

[0015] The cooling water outlet of the second condenser is connected to the second inner zone water distribution gate through a second return water pipe, and the second return water pipe is also connected to a second return water bypass pipe, and the second return water bypass pipe is connected to the water collection tank of the second cooling tower;

[0016] The outlet channel of the second cooling tower is connected to the water supply pipe of the second condenser through the second circulating water pump; the second return water bypass pipe and the second return water pipe located behind the second return water bypass pipe are both provided with a second isolation valve;

[0017] A return water connecting pipe is connected between the first return water pipe located in front of the first return water surpassing pipe and the second return water pipe located in front of the second return water surpassing pipe. A return water connecting pipe isolation valve is provided on the return water connecting pipe.

[0018] As a preferred solution, a second closed return water channel is connected between the water outlet of the second cooling tower and the second circulating water pump.

[0019] As a preferred solution, the water outlets of the first condenser and the second condenser are both connected to auxiliary machine cooling water systems, and each of the auxiliary machine cooling water systems is respectively connected to the corresponding first return water pipe or second return water pipe.

[0020] As a preferred solution, the tail end of the first return water bypass pipe and the tail end of the second return water bypass pipe are both connected to an energy dissipation mixing tank, and each of the energy dissipation mixing tanks is respectively connected to the corresponding water collection tank of the first cooling tower or the water collection tank of the second cooling tower.

[0021] As a preferred solution, the outlet of the water collecting tank of the first cooling tower and the outlet of the water collecting tank of the second cooling tower are both provided with a liquid level gauge and a thermometer.

[0022] As a preferred solution, it also includes a controller, which is electrically connected to the liquid level meter, the thermometer, the first isolation valve, the second isolation valve, the return water connecting pipe isolation valve, the first circulating water pump and the second circulating water pump.

[0023] As a preferred solution, the air inlets of the first cooling tower and the second cooling tower are both provided with windproof water curtain spray pipes.

[0024] As a preferred solution, the first circulating water pump and the second circulating water pump each include two water pumps arranged in parallel.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The circulating cooling system for preventing the condenser inlet water temperature from being too cold of the present invention includes a first condenser and a first cooling tower; the water distribution area of ​​the first cooling tower includes a first inner area and a first outer area arranged inside and outside, and the first inner area is provided with a first inner area water distribution gate for controlling whether the spray pipe on the first inner area distributes water, and for controlling whether the spray pipe on the first outer area distributes water; the cooling water outlet of the first condenser is connected to the first inner area water distribution gate through a first return water pipe, and the first return water pipe is also connected to a first return water bypass pipe, and the first return water bypass pipe is connected to the water collecting tank of the first cooling tower; the outlet channel of the first cooling tower is connected to the water supply pipe of the first condenser through a first circulating water pump, so that the water after cooling by the first cooling tower is discharged into the first condenser through the first circulating water pump; a first isolation valve is provided on the first return water bypass pipe and the first return water pipe located on the rear side of the first return water bypass pipe, and the first isolation valve is used to control the on-off of the first return water bypass pipe and the first return water pipe.

[0027] The circulating cooling system of the present application prevents the condenser inlet water temperature from being overcooled. The water discharged from the outlet of the first cooling tower can enter the first inner zone and the first outer zone of the first cooling tower through the first return water pipe, and then the outlet of the first cooling tower discharges the water into the first condenser through the first circulating water pump. In order to increase the inlet water temperature of the first condenser, the isolation valve on the first return water bypass pipe can be opened to allow a part of the hot water to enter the water collection tank directly without being cooled and mix with the cooled water to increase the outlet water temperature. At the same time, the water distribution gate in the inner zone of the first cooling tower can be closed, the water sprinkling density in the outer zone can be increased, and the water temperature in the water supply pipe of the first cooling tower can be detected. When the water temperature is lower than 12 degrees, the outlet water temperature of the water in the first cooling tower can be increased by opening the isolation valve on the first return water bypass pipe and closing the water distribution gate in the inner zone of the first cooling tower, so that the outlet water temperature of the first cooling tower is not lower than degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of a circulating cooling system for preventing the condenser inlet water temperature from being overcooled according to the present invention.

[0029] In the figure, 1. first condenser; 2. first cooling tower; 21. first inner zone; 22. first outer zone; 3. first return water pipe; 4. first return water bypass pipe; 5. first circulating water pump; 6. first isolating valve; 7. first closed return water flow channel; 8. second condenser; 9. second cooling tower; 91. second inner zone; 92. second outer zone; 10. second return water pipe; 11. second return water bypass pipe; 12. second circulating water pump; 13. return water connecting pipe; 14. return water connecting pipe isolating valve; 15. second isolating valve; 16. second closed return water flow channel; 17. windproof water curtain spray pipe; 18. auxiliary machine cooling water system; 19. thermometer; 20. liquid level gauge. DETAILED DESCRIPTION

[0030] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0031] In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. It should be understood that the terms "first", "second", etc. are used in the present invention to describe various information, but such information should not be limited to these terms, which are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, "first" information may also be referred to as "second" information, and similarly, "second" information may also be referred to as "first" information.

[0032] The preferred embodiment of the circulating cooling system for preventing the condenser inlet water temperature from being too cold of the present invention is specifically referred to Figure 1 As shown, it includes a first condenser 1 and a first cooling tower 2; the water distribution area of ​​the first cooling tower 2 includes a first inner area 21 and a first outer area 22 arranged inside and outside, and a first inner area water distribution gate is provided on the first inner area 21 to control whether the spray pipe on the first inner area 21 distributes water. A water collecting tank is provided at the bottom of the first cooling tower 2, and the water collecting tank is provided with a thermometer 19 and a liquid level gauge 20; the cooling water outlet of the first condenser 1 is connected to the first inner area water distribution gate through a first return water pipe 3, and the first return water pipe 3 is also connected to The first return water bypass pipe 4 is connected to the water collecting tank of the first cooling tower 2; the outlet channel of the first cooling tower 2 is connected to the water supply pipe of the first condenser 1 through the first circulating water pump 5, so that the water cooled by the first cooling tower 2 is discharged into the first condenser 1 through the first circulating water pump 5; the first return water bypass pipe 4 and the first return water pipe 3 located on the rear side of the first return water bypass pipe 4 are both provided with a first isolation valve 6, and the first isolation valve 6 is used to control the on-off of the first return water bypass pipe 4 and the first return water pipe 3.

[0033] The circulating cooling system of the present application for preventing the condenser inlet water temperature from being overcooled, the water discharged from the outlet of the first cooling tower 2 can enter the first inner zone 21 and the first outer zone 22 of the first cooling tower 2 through the first return water pipe 3, and then the outlet of the first cooling tower 2 discharges the water into the first condenser 1 through the first circulating water pump 5. In order to increase the inlet water temperature of the first condenser 1, the isolation valve on the first return water bypass pipe 4 can be opened to allow a part of the hot water to directly enter the water collection tank without being cooled and mix with the cooled water to increase the outlet water temperature. At the same time, the water distribution gate in the inner zone of the first cooling tower 2 can be closed, the water sprinkling density in the outer zone can be increased, and the water temperature in the water supply pipe of the first cooling tower 2 can be detected. When the water temperature is lower than 12 degrees, the outlet water temperature of the water in the first cooling tower 2 can be increased by opening the isolation valve on the first return water bypass pipe 4 and closing the water distribution gate in the inner zone of the first cooling tower 2, or the windproof water curtain spray pipe 17 can be activated to block the amount of cold air entering the cooling tower, so that the outlet water temperature of the first cooling tower 2 is not lower than 12 degrees.

[0034] Among them, a first closed return water channel 7 is connected between the water outlet of the first cooling tower 2 and the first circulating water pump 5. The provision of the first closed return water channel 7 can reduce heat loss of water at the outlet of the first cooling tower 2 to increase the water temperature.

[0035] Furthermore, in a specific embodiment of the present application, a second condenser 8 and a second cooling tower 9 are further included; the water distribution area of ​​the second cooling tower 9 includes a second inner zone 91 and a second outer zone 92 arranged inside and outside, and a second inner zone water distribution gate is provided on the second inner zone 91 to control whether the spray pipe on the second inner zone 91 distributes water, and a water collection tank is provided at the bottom of the first cooling tower 2; in a specific embodiment of the present application, the specific structures of the first cooling tower 2 and the second cooling tower 9 can be the same or different. The cooling water outlet of the second condenser 8 is connected to the second inner zone water distribution gate through a second return water pipe 10, and a second return water bypass pipe 11 is also connected to the second return water bypass pipe 11, and the second return water bypass pipe 11 is connected to the water collection tank of the second cooling tower 9; the outlet channel of the second cooling tower 9 is connected to the water supply pipe of the second condenser 8 through a second circulating water pump 12; a second isolation valve 15 is provided on the second return water bypass pipe 11 and on the second return water bypass pipe 10 located behind the second return water bypass pipe 11. A return water connecting pipe 13 is connected between the first return water pipe 3 located in front of the first return water bypass pipe 4 and the second return water pipe 10 located in front of the second return water bypass pipe 11 . A return water connecting pipe isolating valve 14 is provided on the return water connecting pipe 13 .

[0036] The outlet channel of the second cooling tower 9 is connected to the water supply pipe of the second condenser 8 through the second circulating water pump 12, so that the water after cooling by the second cooling tower 9 is discharged into the second condenser 8 through the second circulating water pump 12; a second isolation valve 15 is provided on the second return water bypass pipe 11 and the second return water pipe 10 located on the rear side of the second return water bypass pipe 11. The second isolation valve 15 is used to control the on-off of the second return water bypass pipe 11 and the second return water pipe 10. The return water connecting pipe 13 is used to connect the first return water pipe 3 and the second return water pipe 10. The return water connecting pipe isolation valve 14 is used to control the on-off of the return water connecting pipe 13.

[0037] In order to increase the return water temperature of the first condenser 1 and the second condenser 8, close the isolation valve on the first return water pipe 3 or the second return water pipe 10, open the return water connecting pipe isolation valve 14, so that the circulating water of the first condenser 1 and the second condenser 8 can flow back to the first cooling tower 2 or the second cooling tower 9, increase the water spraying density, and improve the water temperature out of the tower.

[0038] In order to further increase the return water temperature of the first condenser 1 and the second condenser 8, the first circulating water pump 5 and the second circulating water pump 12 each include two water pumps arranged in parallel. In this way, in winter, when the first condenser 1 and the second condenser 8 are in steam extraction operation, the two water pumps of the first circulating water pump 5 and the second circulating water pump 12 realize variable frequency operation of one water pump corresponding to one condenser (that is, a total of two circulating water pumps are in operation), reducing the amount of circulating water, increasing the temperature rise of circulating water, and increasing the water temperature out of the tower.

[0039] In a further embodiment of the present application, a second closed return water channel 16 is connected between the water outlet of the second cooling tower 9 and the second circulating water pump 12. The provision of the second closed return water channel 16 can reduce the heat loss of the water at the outlet of the second cooling tower 9 to increase the water temperature.

[0040] The water outlets of the first condenser 1 and the second condenser 8 are both connected to the auxiliary machine cooling water system 18 , and each auxiliary machine cooling water system 18 is connected to the corresponding first return water pipe 3 or second return water pipe 10 .

[0041] In the present application, the tail ends of the first return water bypass pipe 4 and the tail ends of the second return water bypass pipe 11 are both connected to energy dissipation mixing tanks, and each energy dissipation mixing tank is respectively connected to the corresponding water collection tank of the first cooling tower 2 or the water collection tank of the second cooling tower 9.

[0042] Among them, the air inlets of the first cooling tower 2 and the second cooling tower 9 are both provided with windproof water curtain spray pipes 17, which form hot water curtains at the water inlets of the cooling towers, reduce the cold wind entering the cooling towers, and increase the water temperature out of the towers.

[0043] In a specific embodiment of the present application, the outlet of the water collection tank of the first cooling tower 2 and the outlet of the water collection tank of the second cooling tower 9 are both provided with a liquid level gauge and a thermometer. When the water temperature is too low, the inner area water distribution gate or the isolation valve on the return water override pipe can be opened or the windproof water curtain spray pipe can be activated.

[0044] The circulating cooling system for preventing the condenser inlet water temperature from being too cold can control the outlet water temperature of the cooling tower to be no less than 12° C., thereby preventing the condenser pressure from being too low and posing a threat to the safe operation of the turbine.

[0045] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A circulating cooling system for preventing condenser inlet water from being overcooled, characterized in that: including a first condenser and a first cooling tower; The water distribution area of ​​the first cooling tower includes a first inner area and a first outer area arranged inside and outside, and the first inner area is provided with a first inner area water distribution gate; The cooling water outlet of the first condenser is connected to the first inner zone water distribution gate through a first return water pipe, and the first return water pipe is also connected to a first return water bypass pipe, and the first return water bypass pipe is connected to the water collection tank of the first cooling tower; The outlet channel of the first cooling tower is connected to the water supply pipe of the first condenser through the first circulating water pump; A first isolation valve is provided on the first return water bypass pipe and on the first return water pipe located behind the first return water bypass pipe; In order to increase the inlet water temperature of the first condenser, the first isolation valve on the first return water bypass pipe is opened to allow a portion of hot water to enter the water collection tank directly without being cooled and mix with the cooled water, thereby increasing the outlet water temperature. At the same time, the first inner zone water distribution gate on the first inner zone is closed to increase the water spraying density in the outer zone.

2. The circulating cooling system for preventing condenser inlet water from being overcooled according to claim 1, characterized in that: A first closed water return channel is connected between the water outlet of the first cooling tower and the first circulating water pump.

3. The circulating cooling system for preventing condenser inlet water from being overcooled according to claim 1, characterized in that: Also included is a second condenser and a second cooling tower; The water distribution area of ​​the second cooling tower includes a second inner area and a second outer area arranged inside and outside, and the second inner area is provided with a second inner area water distribution gate; The cooling water outlet of the second condenser is connected to the second inner zone water distribution gate through a second return water pipe, and the second return water pipe is also connected to a second return water bypass pipe, and the second return water bypass pipe is connected to the water collection tank of the second cooling tower; The outlet channel of the second cooling tower is connected to the water supply pipe of the second condenser through the second circulating water pump; the second return water bypass pipe and the second return water pipe located behind the second return water bypass pipe are both provided with a second isolation valve; A return water connecting pipe is connected between the first return water pipe located in front of the first return water surpassing pipe and the second return water pipe located in front of the second return water surpassing pipe. A return water connecting pipe isolation valve is provided on the return water connecting pipe.

4. The circulating cooling system for preventing condenser inlet water from being overcooled according to claim 3, characterized in that: A second closed water return channel is connected between the water outlet of the second cooling tower and the second circulating water pump.

5. The circulating cooling system for preventing condenser inlet water from being overcooled according to claim 3, characterized in that: The water outlets of the first condenser and the second condenser are both connected to auxiliary machine cooling water systems, and each of the auxiliary machine cooling water systems is respectively connected to the corresponding first return water pipe or second return water pipe.

6. The circulating cooling system for preventing condenser inlet water from being overcooled according to claim 3, characterized in that: The tail end of the first return water bypass pipe and the tail end of the second return water bypass pipe are both connected to an energy dissipation mixing tank, and each energy dissipation mixing tank is respectively connected to the corresponding water collection tank of the first cooling tower or the water collection tank of the second cooling tower.

7. The circulating cooling system for preventing condenser inlet water from being overcooled according to claim 3, characterized in that: The outlet of the water collecting tank of the first cooling tower and the outlet of the water collecting tank of the second cooling tower are both provided with a liquid level gauge and a thermometer.

8. The circulating cooling system for preventing condenser inlet water from being overcooled according to claim 7, characterized in that: It also includes a controller, which is electrically connected to the liquid level meter, the thermometer, the first isolation valve, the second isolation valve, the return water connecting pipe isolation valve, the first circulating water pump and the second circulating water pump.

9. The circulating cooling system for preventing condenser inlet water from being overcooled according to claim 3, characterized in that: The air inlets of the first cooling tower and the second cooling tower are both provided with windproof water curtain spray pipes.

10. The circulating cooling system for preventing condenser inlet water from being overcooled according to claim 3, characterized in that: The first circulating water pump and the second circulating water pump each include two water pumps arranged in parallel.

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