Novel anti-freezing system for direct air cooling unit after cylinder cutting of power plant

Abstract

A novel direct air cooling unit anti-freezing system after cylinder switching of a power plant comprises an intermediate-pressure cylinder, a steam exhaust pipeline of the intermediate-pressure cylinder is communicated with an inlet of an anti-freezing steam extraction pipeline, an outlet of the anti-freezing steam extraction pipeline is connected with a turbine condenser, the turbine condenser is communicated with a hot well, the hot well is connected with a DCS control cabinet through a hot well temperature measuring element, and the DCS control cabinet is connected with an electric control valve. The steam turbine condenser comprises a body drain flash tank and a steam turbine exhaust device, an outlet of the anti-freezing steam extraction pipeline is connected with an inlet of the body drain flash tank, and an outlet of the steam turbine exhaust device is connected with an inlet of the air cooling island main steam pipeline; a plurality of air cooling island steam branch pipes are arranged on the air cooling island device, inlets of the plurality of air cooling island steam branch pipes are respectively communicated with an outlet of the air cooling island main steam pipeline, and outlets of the plurality of air cooling island steam branch pipes are connected to the air cooling island device; during cylinder switching heat supply, a part of steam is extracted from the medium-pressure cylinder, the defect that the air cooling island is prone to frost crack due to insufficient steam inlet is overcome, the anti-freezing steam flow can be accurately controlled through the DCS control cabinet, the system is simple, and the manufacturing cost is low.

Description

Technical Field

[0001] The utility model belongs to the technical field of air cooling island antifreeze and auxiliary machine energy saving, and specifically relates to a novel antifreeze system for a direct air cooling unit after cylinder cutting in a power plant. Background Art

[0002] In order to meet the increasing demand for heating, some direct air-cooled units need to undergo low-pressure cylinder removal and transformation, leaving only a small amount of cooling steam to enter the low-pressure cylinder, and the remaining steam enters the heat network heater or directly supplies industrial steam to the outside through the exhaust steam of the medium-pressure cylinder. At this time, only the steam for cooling the low-pressure cylinder of the steam turbine enters the air-cooled island, and the steam volume is small. When encountering cold weather in the north, the air-cooled island may freeze and crack due to insufficient steam volume.

[0003] Patent application number 201911341713.3 discloses an air-cooling island antifreeze device for a direct air-cooled generator set after cylinder cutting and modification, and specifically discloses a temperature reduction valve group, a temperature reduction water pipe, a temperature reduction and pressure reduction device, an air-cooling island steam main pipe, an antifreeze steam main pipe, an air-cooling island and a plurality of air-cooling island steam branch pipes; the air-cooling island is provided with a plurality of air-cooling island steam branch pipes, and the plurality of air-cooling island steam branch pipes are respectively connected to the air-cooling island steam main pipe, the air-cooling island steam main pipe is connected to the antifreeze steam main pipe, a temperature reduction and pressure reduction device is provided on the antifreeze steam main pipe, the water inlet of the temperature reduction and pressure reduction device is connected to the temperature reduction water pipe, and a temperature reduction valve group is provided on the temperature reduction water pipe; in the above-mentioned patent, high-pressure steam generates low-temperature and low-pressure steam through the temperature reduction and pressure reduction device and the temperature reduction valve group to enter the air-cooling island, so as to make up for the problem of freezing and cracking of the air-cooling island caused by insufficient steam when the low-pressure cylinder of the steam turbine is cut off, but the steam inlet flow entering the air-cooling island cannot be accurately adjusted, and the cost of using the temperature reduction and pressure reduction device and the temperature reduction valve group is high.

[0004] To this end, the technical problem to be solved by the utility model is: in the above-mentioned patent, when the unit is in the cylinder cutting heating state, the high-pressure steam generates low-temperature and low-pressure steam through the temperature reducing and pressure reducing device and the temperature reducing valve group to enter the air cooling island, but the steam flow entering the air cooling island cannot be accurately adjusted, and the cost of using the temperature reducing and pressure reducing device and the temperature reducing valve group is high. Utility Model Content

[0005] In order to solve the technical problems in the above-mentioned patent that when the unit is in the cylinder cutting heating state, the high-pressure steam generates low-temperature and low-pressure steam through the temperature reducing and pressure reducing device and the temperature reducing valve group to enter the air cooling island, but the steam flow entering the air cooling island cannot be accurately adjusted, and the cost of using the temperature reducing and pressure reducing device and the temperature reducing valve group is high, the utility model provides a new antifreeze system for direct air cooling units after cylinder cutting in power plants.

[0006] The specific plan is as follows:

[0007] A novel antifreeze system for a power plant unit directly air-cooled after cylinder cutting, comprising an intermediate pressure cylinder, the exhaust pipe of the intermediate pressure cylinder is connected to the inlet of an antifreeze extraction pipe, the outlet of the antifreeze extraction pipe is connected to a steam turbine condenser, the steam turbine condenser is connected to a hot well, the hot well is connected to a DCS control cabinet through a hot well temperature measuring element, and the DCS control cabinet is connected to an electric regulating valve;

[0008] The steam turbine condenser comprises a main body drain expansion tank and a steam turbine exhaust device, the outlet of the antifreeze extraction pipeline is connected to the inlet of the main body drain expansion tank, and the outlet of the steam turbine exhaust device is connected to the inlet of the main steam pipeline of the air cooling island;

[0009] The air-cooling island device is provided with a plurality of air-cooling island steam branch pipes, the inlets of the plurality of air-cooling island steam branch pipes are respectively connected to the outlets of the air-cooling island main steam pipeline, and the outlets of the plurality of air-cooling island steam branch pipes are all connected to the air-cooling island device.

[0010] An electric stop valve is provided at one end of the antifreeze steam extraction pipeline on the steam inlet side.

[0011] An electric vacuum stop valve is provided on the antifreeze steam extraction pipeline on the steam inlet side of the main body drain expansion tank.

[0012] The antifreeze steam extraction pipeline is also provided with a flow meter and an electric regulating valve, and the flow meter and the electric regulating valve are both arranged on the antifreeze steam extraction pipeline between the electric stop valve and the electric vacuum stop valve.

[0013] The air-cooling island steam branch pipe is provided with an air-cooling island steam branch pipe electric regulating butterfly valve.

[0014] The beneficial effects of the utility model are:

[0015] The utility model extracts a part of steam from the intermediate pressure cylinder when the unit is in the cylinder cutting heating state, the steam enters the steam turbine exhaust device after the pressure is reduced and the volume is expanded to become a vacuum through the main body drain expansion tank, the steam is subjected to temperature and pressure reduction treatment by the steam turbine condenser, the treated steam enters the air cooling island device and is cooled into condensate, the temperature of the condensate from the air cooling island is detected in real time by the hot well temperature measuring element, and the temperature signal is transmitted to the DCS control cabinet, if the measured temperature value of the condensate from the air cooling island is lower than the preset value, the DCS control cabinet controls the valve opening of the electric regulating valve, thereby accurately adjusting the steam flow entering the air cooling island device, thereby preventing the air cooling island from freezing and cracking, the system is simple and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the antifreeze system of the utility model for the direct air-cooling unit after cylinder cutting in a power plant.

[0017] Among them, 1-intermediate pressure cylinder; 2-antifreeze extraction steam pipeline; 3-electric stop valve; 4-flow meter; 5-electric regulating valve; 6-electric vacuum stop valve; 7-body drain expansion tank; 8-turbine exhaust device; 9-air cooling island main steam pipeline; 10-air cooling island steam branch electric regulating butterfly valve; 11-air cooling island device; 12-air cooling island steam branch; 13-hot well; 14-hot well temperature measuring element; 15-DCS control cabinet DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the implementation of the utility model, not all of the implementation. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0019] like Figure 1 As shown, a novel antifreeze system for a direct air-cooled unit after cylinder cutting in a power plant comprises an intermediate pressure cylinder 1, the exhaust pipe of the intermediate pressure cylinder 1 is connected to the inlet of an antifreeze extraction pipe 2, the outlet of the antifreeze extraction pipe 2 is connected to a steam turbine condenser, the steam turbine condenser is connected to a hot well 13, the hot well 13 is connected to a DCS control cabinet 15 through a hot well temperature measuring element 14, and the DCS control cabinet 15 is connected to an electric regulating valve 5;

[0020] The steam turbine condenser comprises a main body drain expansion tank 7 and a steam turbine exhaust device 8, the outlet of the antifreeze extraction pipe 2 is connected to the inlet of the main body drain expansion tank 7, and the outlet of the steam turbine exhaust device 8 is connected to the inlet of the main steam pipe 9 of the air cooling island;

[0021] The air-cooling island device 11 is provided with a plurality of air-cooling island steam branch pipes 12 , the inlets of which are respectively connected to the outlets of the air-cooling island main steam pipeline 9 , and the outlets of which are all connected to the air-cooling island device 11 .

[0022] When the unit is in the cylinder cutting heating state, the utility model extracts a part of steam from the intermediate pressure cylinder 1, and the steam enters the turbine exhaust device 8 after the steam is reduced in pressure and expanded in volume to become a vacuum through the main body drain expansion tank 7, and the steam is cooled and reduced in pressure by the turbine condenser, and the treated steam enters the air cooling island device to be cooled into condensate, and the temperature of the condensate from the air cooling island is detected in real time by the hot well temperature measuring element 14, and the temperature signal is transmitted to the DCS control cabinet 15. If the measured temperature value of the condensate from the air cooling island is lower than the preset value, the DCS control cabinet 15 controls the valve opening of the electric regulating valve 5, so as to accurately adjust the steam flow entering the air cooling island device 11, thereby preventing the air cooling island from freezing and cracking, and the system is simple and the cost is low.

[0023] An electric stop valve 3 is provided at one end of the steam inlet side of the antifreeze steam extraction pipeline 2, and the transmission of steam in the antifreeze steam extraction pipeline 2 is controlled by switching the electric stop valve 3, that is, the opening and closing of the air-cooling island antifreeze steam extraction system is controlled.

[0024] An electric vacuum stop valve 6 is provided on the antifreeze steam extraction pipeline 2 on the steam inlet side of the main body hydrophobic expansion tank 7. Since the steam in front of the electric vacuum stop valve 6 is positive pressure steam and the condenser is a vacuum environment, the electric vacuum stop valve 6 is provided in front of the condenser to isolate the vacuum environment from the external environment, so that the vacuum environment is not polluted by the external environment.

[0025] The antifreeze steam extraction pipeline 2 is also provided with a flow meter 4 and an electric regulating valve 5, and the flow meter 4 and the electric regulating valve 5 are both arranged on the antifreeze steam extraction pipeline 2 between the electric stop valve 3 and the electric vacuum stop valve 6; the antifreeze steam extraction amount entering the air-cooling island device can be monitored in real time through the flow meter 4; the temperature of the condensate from the air-cooling island is detected by the hot well temperature measuring element 14, and the temperature signal is transmitted to the DCS control cabinet 15. If the measured temperature value of the condensate from the air-cooling island is lower than the preset value, the DCS control cabinet 15 controls the valve opening of the electric regulating valve 5, and then accurately adjusts the steam flow flowing through the antifreeze steam extraction pipeline 2, thereby adjusting the steam flow entering the main steam pipeline 9 of the air-cooling island to prevent the air-cooling island from freezing and cracking.

[0026] In the utility model, the steam turbine condenser is used to create a relatively high vacuum at the exhaust port of the steam turbine, so that the steam expands to the minimum pressure in the steam turbine, increases the available enthalpy drop of the steam in the steam turbine, and improves the cycle thermal efficiency. The steam is reduced in pressure and expanded in volume to become a vacuum through the main body hydrophobic expansion tank 7 and then enters the steam turbine exhaust device 8, thereby reducing the temperature and pressure of the steam.

[0027] The air-cooling island steam branch pipe 12 is provided with an air-cooling island steam branch pipe electric regulating butterfly valve 10, and the air-cooling island steam branch pipe electric regulating butterfly valve 10 can adjust the steam flow from the air-cooling island steam branch pipe 12 into the air-cooling island.

[0028] The air-cooling island device 11 is composed of a plurality of air-cooling units, each of which is connected to the air-cooling island main steam pipeline 9 via an air-cooling island steam branch pipe 12, so as to ensure that steam is provided to each air-cooling unit.

[0029] The specific working process of the utility model is:

[0030] When the unit is cut off from the cylinder for heating in winter, the electric stop valve 3 is opened to open the air-cooling island antifreeze extraction system, that is, part of the steam from the medium-pressure cylinder 1 enters the antifreeze extraction pipeline 2 through the pipeline, and the steam enters the main body drain expansion tank 7 after passing through the electric stop valve 3, the flow meter 4, the electric regulating valve 5, and the electric vacuum stop valve 6 in sequence. The steam is reduced in pressure and expanded in volume to become a vacuum through the main body drain expansion tank 7 and then enters the turbine exhaust device 8. The steam from the turbine exhaust device 8 enters the air-cooling island steam through the air-cooling island main steam pipeline 9. In the steam branch pipe 12, the steam enters the air cooling device 11 through the air cooling island steam branch pipe 12, and the steam is cooled into condensed water in the air cooling island device 11. In this process, the hot well temperature measuring element 14 detects the condensed water temperature from the air cooling island in real time, and transmits the temperature signal to the DCS control cabinet 15. If the measured temperature value of the condensed water in the air cooling island is lower than the preset value, the DCS control cabinet 15 controls the valve opening of the electric regulating valve 5, and then accurately adjusts the steam flow flowing through the antifreeze extraction steam pipeline 2, thereby adjusting the steam flow entering the main steam pipeline 9 of the air cooling island;

[0031] When the unit operates normally, the exhaust steam load increases, multiple rows of air cooling units are opened, and the electric stop valve 3 is closed, thereby closing the air cooling island antifreeze extraction steam system.

[0032] When the unit of the utility model cuts off the cylinders to provide heating in winter, there is no need to isolate the air-cooling island. It only needs to extract a part of the steam from the medium-pressure cylinder and enter the air-cooling island through the condenser to avoid freezing and cracking of the air-cooling island due to the small amount of steam entering the low-pressure cylinder after the cylinder cuts off. That is, the steam entering the air-cooling island is cooled into condensed water, and the condensed water enters the hot well through the pipeline. The temperature of the condensed water from the air-cooling island is measured by the set hot well temperature measuring element 14. If the measured temperature value is lower than the preset value, the valve opening of the electric regulating valve 5 is controlled by the DCS control cabinet 15 to accurately control the steam flow entering the air-cooling island, so as to meet the minimum freezing flow of the air-cooling island. The utility model can accurately adjust the antifreeze steam flow entering the air-cooling island, and the system is simple, reliable and economical.

[0033] The technical means disclosed in the solution of the utility model are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical solutions composed of any combination of the above technical features. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the utility model, and these improvements and modifications are also regarded as the protection scope of the utility model.

Claims

1. A new type of antifreeze system for air-cooled units directly after cylinder cutting in power plants, characterized by: It comprises an intermediate pressure cylinder (1), the exhaust pipe of the intermediate pressure cylinder (1) is connected to the inlet of the antifreeze extraction pipe (2), the outlet of the antifreeze extraction pipe (2) is connected to the steam turbine condenser, the steam turbine condenser is connected to the hot well (13), the hot well (13) is connected to the DCS control cabinet (15) via the hot well temperature measuring element (14), and the DCS control cabinet (15) is connected to the electric regulating valve (5); The steam turbine condenser comprises a main body drain expansion tank (7) and a steam turbine exhaust device (8), the outlet of the antifreeze extraction pipe (2) is connected to the inlet of the main body drain expansion tank (7), and the outlet of the steam turbine exhaust device (8) is connected to the inlet of the main steam pipe (9) of the air cooling island; The air-cooling island device (11) is provided with a plurality of air-cooling island steam branch pipes (12), the inlets of the plurality of air-cooling island steam branch pipes (12) are respectively connected to the outlets of the air-cooling island main steam pipeline (9), and the outlets of the plurality of air-cooling island steam branch pipes (12) are all connected to the air-cooling island device (11).

2. The novel antifreeze system for air-cooled units after cylinder cutting in power plants according to claim 1 is characterized by: An electric stop valve (3) is provided at one end of the antifreeze steam extraction pipeline (2) on the steam inlet side.

3. The novel antifreeze system for air-cooled units after cylinder cutting in power plants according to claim 1 is characterized by: An electric vacuum stop valve (6) is provided on the antifreeze steam extraction pipeline (2) on the steam inlet side of the main body drain expansion tank (7).

4. The novel antifreeze system for air-cooled units after cylinder cutting in power plants according to claim 1 is characterized by: The antifreeze steam extraction pipeline (2) is also provided with a flow meter (4) and an electric regulating valve (5), and the flow meter (4) and the electric regulating valve (5) are both arranged on the antifreeze steam extraction pipeline (2) between the electric stop valve (3) and the electric vacuum stop valve (6).

5. The novel antifreeze system for air-cooled units after cylinder cutting in power plants according to claim 1 is characterized in that: The air-cooling island steam branch pipe (12) is provided with an air-cooling island steam branch pipe electric regulating butterfly valve (10).

Images