A steam turbine high back pressure heating and power generation system

Abstract

The present invention relates to a steam turbine high back pressure heating and power generation system, which comprises a heat network user, a condenser assembly, a mechanical cooling tower and at least two groups of direct air cooling assemblies, wherein the direct air cooling assembly comprises an air cooling unit, a circulating water pump, an air cooling island and a heat network peak shaving heater; the exhaust pipe of the low pressure cylinder is connected to the air cooling island, and the exhaust pipe of the low pressure cylinder is connected to the condenser assembly; the condenser assembly and the heat network user form a first circulating water loop, and the condenser assembly and the mechanical cooling tower form a second circulating water loop; the extraction pipe of the intermediate pressure cylinder is connected to the heat network peak shaving heater, and the heat network peak shaving heater can be selectively connected to the first circulating water loop; the condenser assembly comprises at least two surface condensers arranged in parallel, and the number of the surface condensers is not less than the number of the direct air cooling assemblies. The steam turbine high back pressure heating and power generation system can be combined with heat users to perform heat and power cogeneration, improve equipment utilization, effectively recover steam exhaust waste heat of the steam turbine and stabilize the back pressure of the air cooling unit.

Description

Technical Field

[0001] The invention relates to the technical field of heating in thermal power plants, and in particular to a steam turbine high back pressure heating and power generation cogeneration system. Background Art

[0002] With the acceleration of urbanization, the area of ​​centralized heating in northern China has grown rapidly. As the heat supply center of the city, thermal power plants play an extremely important role in the process of centralized heating in cities. The north of my country, especially the northwest, is rich in coal and short of water. There is a very large demand for heat in the cold season. Therefore, direct air-cooled heating units have strong functional adaptability in northern my country. Improving energy utilization and strengthening waste heat recovery are important measures to save energy, reduce carbon emissions and protect the environment.

[0003] At present, the direct air-cooled units of thermal power plants change the traditional steam extraction heating method in winter to high back pressure heating, which can improve the economic efficiency of the units and significantly reduce coal consumption. However, the high back pressure heating transformation of direct air-cooled units requires the addition of surface condensers, but surface condensers are only used during the winter heating period and are idle at other times, resulting in low equipment utilization.

[0004] In addition, direct air-cooling units have a high back pressure when operating in summer and their full-power capacity is limited, especially under high temperature and windy conditions, which can easily cause the back pressure of the air-cooling units to be unstable and the output to be insufficient.

[0005] Therefore, how to combine heat users for cogeneration, improve equipment utilization, effectively recover steam waste heat from turbines and stabilize the back pressure of air-cooled units is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0006] The purpose of the present invention is to provide a steam turbine high back pressure heating and power generation system, which can combine heat users to perform cogeneration, improve equipment utilization, effectively recover steam turbine exhaust heat and stabilize the back pressure of the air cooling unit.

[0007] In order to solve the above technical problems, the present invention provides a steam turbine high back pressure heating and power generation system, which includes a heat network user, a condenser assembly, a mechanical cooling tower and at least two groups of direct air cooling assemblies, the direct air cooling assembly includes an air cooling unit, a circulating water pump, an air cooling island and a heat network peak-shaving heater, each of the air cooling units includes a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder; the exhaust pipe of the low-pressure cylinder is connected to the air cooling island through a first control valve, and the exhaust pipe of the low-pressure cylinder is connected to the condenser assembly through a second control valve, the condenser assembly and each of the air cooling islands are connected in parallel; the condenser assembly is provided with a third control valve The pipeline of the valve forms a first circulating water loop with the user of the heating network, and the condenser assembly forms a second circulating water loop with the mechanical cooling tower through a pipeline provided with a fourth control valve. The mechanical cooling tower and the user of the heating network are connected in parallel, and the circulating water pump is provided on the return pipe side of the condenser assembly; the extraction steam of the intermediate pressure cylinder is connected to the peak-shaving heater of the heating network through an extraction steam regulating valve, and the peak-shaving heater of the heating network can be selectively connected to the first circulating water loop; the condenser assembly includes at least two surface condensers arranged in parallel, and the number of the surface condensers is not less than the number of the direct air cooling assembly.

[0008] The surface condenser acts as the primary heat exchanger of the heat network. By increasing the exhaust back pressure of the low-pressure cylinder, the high-temperature steam heat source of the low-pressure cylinder exhaust is used to heat the return water of the heat network (the water in the first circulating water loop) to provide heat to the users of the heat network. That is, the exhaust heat energy of the steam turbine is recovered to reduce or eliminate the air intake of the air-cooling island, thereby effectively reducing the cold source loss of the air-cooling unit, improving energy utilization, reducing coal consumption for power generation, and saving energy and protecting the environment.

[0009] Using surface condensers and mechanical cooling towers as summer peak coolers for the unit can achieve full peak load of the unit in summer and ensure safe summer operation. This not only improves equipment utilization, but also effectively reduces coal consumption for power generation of air-cooled units.

[0010] The steam turbine high back pressure heating and power generation system combines heat users to carry out cogeneration of heat and power, which can effectively recover the waste heat of steam turbine exhaust steam, reduce the cold end loss of thermal power plants, and achieve the effect of energy conservation and emission reduction.

[0011] In addition, each group of direct air-cooling components may have at least one surface condenser corresponding to it. At the same time, the direct air-cooling components may correspond to two or more surface condensers. When in use, single-machine operation can be realized, that is, each direct air-cooling component corresponds to one surface condenser, and the redundant surface condensers are used as backup. Dual-machine or multi-machine operation can also be realized, that is, each direct air-cooling component corresponds to at least two surface condensers. The operation is flexible, the load adjustment capability is strong, the system is simple, the maintenance is convenient, and the reliability is high.

[0012] Optionally, the number of the air cooling units and the number of the surface condensers are both two.

[0013] Optionally, the two second control valves are connected via a steam pipeline, the steam pipeline is connected to the two surface condensers respectively, and a steam isolation valve is provided between the connection point between the steam pipeline and the two surface condensers.

[0014] Optionally, each of the direct air cooling components also includes a steam exhaust device and a condensate pump. The condensate outlet of each surface condenser and the condensate outlet of the air cooling island are respectively connected to the steam exhaust device through a condensate pipeline, and the condensate pump is arranged between the steam exhaust device and the turbine heat recovery system.

[0015] Optionally, the condensate pipeline between the two exhaust devices is connected and provided with a condensate isolation valve, the condensate pipeline is connected with each of the surface condensers respectively, and the condensate isolation valves are respectively provided on both sides of the connection between the condensate pipeline and each of the surface condensers.

[0016] Optionally, the third control valve includes a first valve and a second valve arranged in parallel, and the second valve is connected in series with the heating network peak-shaving heater.

[0017] Optionally, the heating network users include short-distance users and long-distance users arranged in parallel.

[0018] Optionally, the air-cooling island includes at least two air-cooling heat exchangers arranged in parallel, and the first control valve is provided at the inlet of each of the air-cooling heat exchangers. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a steam turbine high back pressure heating and power generation system provided by an embodiment of the present invention;

[0020] Figure 2 yes Figure 1 A is an enlarged view of the middle image.

[0021] Attached Figure 1-2 In the figure, the reference numerals are described as follows:

[0022] 1-heating network user; 2-condenser assembly, 21-surface condenser; 3-mechanical cooling tower; 4-air-cooling unit; 5-circulating water pump; 6-air-cooling island, 61-air-cooling heat exchanger; 7-first control valve; 8-second control valve; 9-third control valve, 91-first valve, 92-second valve; 10-fourth control valve; 11-heating network peak-shaving heater; 12-extraction regulating valve; 13-steam pipeline; 14-steam isolation valve; 15-exhaust device; 16-condensate pump; 17-condensate pipeline; 18-condensate isolation valve. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0024] Please refer to Figure 1-2 , Figure 1 It is a structural schematic diagram of a steam turbine high back pressure heating and power generation system provided by an embodiment of the present invention; Figure 2 yes Figure 1 A is an enlarged view of the middle image.

[0025] The embodiment of the present invention provides a steam turbine high back pressure heating and power generation system, such as Figure 1 and Figure 2 As shown, the steam turbine high back pressure heating and power generation system includes a heat network user 1, a condenser component 2, a mechanical cooling tower 3 and at least two groups of direct air cooling components. The direct air cooling components include an air cooling unit 4, a circulating water pump 5, an air cooling island 6 and a heat network peak-shaving heater 11. Each air cooling unit 4 includes a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder. The exhaust pipe of the low-pressure cylinder of the air-cooled unit 4 is connected to the air-cooled island 6 through the first control valve 7, and the exhaust pipe of the low-pressure cylinder is connected to the condenser assembly 2 through the second control valve 8, and the condenser assembly 2 and each air-cooled island 6 are connected in parallel; the condenser assembly 2 (each surface condenser 21 inside) forms a first circulating water loop with the heat network user 1 through a pipeline provided with a third control valve 9, and the condenser assembly 2 (each surface condenser 21 inside) forms a second circulating water loop with the mechanical cooling tower 3 through a pipeline provided with a fourth control valve 10, the mechanical cooling tower 3 and the heat network user 1 are connected in parallel, and a circulating water pump 5 is provided on the return pipe side of the condenser assembly 2; the extraction pipe of the medium-pressure cylinder is connected to the heat network peak-shaving heater 11 through the extraction regulating valve 12, and the heat network peak-shaving heater 11 can be selectively connected to the first circulating water loop.

[0026] In this embodiment, the condenser assembly 2 includes at least two surface condensers 21 arranged in parallel, and the number of surface condensers 21 is not less than the number of direct air cooling assemblies to ensure that at the same time, each group of direct air cooling assemblies can have at least one surface condenser 21 corresponding to it.

[0027] Specifically, in winter, when it is necessary to supply heat to the heating network user 1, the second control valve 8 is opened, and the low-pressure cylinder exhaust steam of the air-cooling unit 4 enters the surface condenser 21 and exchanges heat with the water inside it, and the surface condenser 21 is connected to the first circulating water loop, that is, the low-pressure cylinder exhaust steam enters the surface condenser 21 to heat the water in the first circulating water loop, and then supplies heat to the heating network user 1 in the first circulating water loop.

[0028] The specific heating situation can be adjusted according to the specific needs of the heating network user 1. For example, when the heat demand of the heating network user 1 is low, the first control valve 7 and the second control valve 8 are opened at the same time. At this time, a part of the low-pressure cylinder exhaust steam enters the surface condenser 21 to exchange heat with the water in the first circulating water loop, and the other part of the low-pressure cylinder exhaust steam enters the air-cooling island 6 for cooling. By adjusting the opening of the first control valve 7 and the second control valve 8, the amount of steam from the low-pressure cylinder exhaust steam entering the surface condenser 21 can be adjusted to meet the heating demand of the heating network user 1.

[0029] When the winter is cold and the heating demand of the heating network user 1 is high, and the high back pressure heating capacity of the unit cannot meet the heating demand of the heating network user 1, the heating network peak-shaving heater 11 is connected to the first circulating water loop. The heating network peak-shaving heater 11 heats the water inside it through the extraction steam of the medium-pressure cylinder to further increase the temperature of the water in the first circulating water loop to ensure that the heating demand of the heating network user 1 is met, that is, the heating network peak-shaving heater can play a heating peak-shaving function in the cold winter.

[0030] That is to say, in this embodiment, the surface condenser 21 of the condenser assembly 2 acts as a primary heat exchanger of the heat network, and increases the exhaust back pressure of the low-pressure cylinder and utilizes the steam heat source with a higher temperature of the exhaust steam of the low-pressure cylinder to heat the return water of the heat network (the water in the first circulating water loop) to provide heat to the heat network user 1, that is, to recover the exhaust steam heat energy of the steam turbine, thereby reducing the steam intake of the air-cooling island 6 or achieving zero air intake, thereby effectively reducing the cold source loss of the air-cooling unit 4, improving energy utilization, reducing coal consumption in power generation, and saving energy and protecting the environment.

[0031] When the heating network user 1 does not need heating, the exhaust steam of the low-pressure cylinder can be directly cooled through the air-cooling island 6. When the temperature is high in summer and the air-cooling island 6 cannot meet the cooling demand, the first control valve 7 and the fourth control valve 10 are opened and the third control valve 9 is closed. At this time, the first circulating water loop is disconnected and the second circulating water loop is connected. The mechanical cooling tower 3 is used to cool the water in the second circulating water loop, that is, the air-cooling island 6 and the surface condenser 21 are used to reduce the temperature of the exhaust steam from the low-pressure cylinder of the turbine, reduce the back pressure of the air-cooling unit 4 and ensure the stability of the back pressure of the air-cooling unit 4, thereby ensuring the safety and economy of the air-cooling unit 4.

[0032] That is to say, by using the surface condenser 21 and the mechanical cooling tower 3 as the summer peak cooler of the unit, the unit can achieve full peak load in summer and ensure safe summer operation, which not only improves the equipment utilization rate, but also effectively reduces the coal consumption of the air-cooled unit 4 for power generation.

[0033] The steam turbine high back pressure heating and power generation system combines heat users to carry out cogeneration of heat and power, which can effectively recover the waste heat of steam turbine exhaust steam, reduce the cold end loss of thermal power plants, and achieve the effect of energy conservation and emission reduction.

[0034] In addition, each group of direct air-cooling components may have at least one surface condenser 21 corresponding to it. Specifically, when each group of direct air-cooling components operates in correspondence with one surface condenser 21 (i.e., single-machine operation mode), the redundant surface condenser 21 serves as a backup; or at the same time, each group of direct air-cooling components may also correspond to two or more surface condensers 21 (i.e., dual-machine or multi-machine operation mode), with flexible operation, strong load adjustment capability, simple system, convenient maintenance and high reliability.

[0035] In the above embodiment, the number of air-cooling units 4 (direct cooling components) and the number of surface condensers 21 are both two. Of course, in this embodiment, the number of air-cooling units 4 and the number of surface condensers 21 can also be set to three or more, and the two numbers can be the same or different, which is not required here. As long as all air-cooling units 4 are operated at the same time, each air-cooling unit 4 can have at least one surface condenser 21 corresponding to it. Setting the number of air-cooling units 4 (direct cooling components) and the number of surface condensers 21 to two can meet the current use requirements of thermal power plants and is beneficial to the layout of the site.

[0036] In the above embodiment, the two second control valves 8 are connected through the steam pipeline 13, the steam pipeline 13 is respectively connected to the two surface condensers 21, and a steam isolation valve 14 is provided between the connection point between the steam pipeline 13 and the two surface condensers 21. In other words, the pipelines connecting the exhaust steam of the two low-pressure cylinders and the condenser assembly 2 are connected, wherein a second control valve 8 is provided between each low-pressure cylinder exhaust steam and the condenser assembly 2, a steam isolation valve 14 is provided between the two second control valves 8, and the steam pipeline 13 between the steam isolation valve 14 and the second control valve 8 is connected to the surface condenser 21. At this time, there are three operating conditions. One operating condition is that when the steam isolation valve 14 is closed and the two second control valves 8 are opened, the two air-cooling units 4 respectively operate corresponding to one surface condenser 21; the other two operating conditions are that when one second control valve 8 is closed and the other second control valve 8 is opened, if the steam isolation valve 14 is opened, one air-cooling unit 4 operates corresponding to two surface condensers 21 at the same time, and if the steam isolation valve 14 is closed, one air-cooling unit 4 operates corresponding to one surface condenser 21, and the other surface condenser 21 is used as a standby.

[0037] Of course, in this embodiment, the steam pipeline 13 between the two second control valves 8 can also be set to be disconnected. In this case, the exhaust steam of each low-pressure cylinder is separately connected to the two surface condensers 21 through the steam pipeline 13 and corresponding valves are set for control. The scheme of connecting the steam pipeline 13 between the two second control valves 8 can simplify the overall structure, facilitate operation, and has good flexibility.

[0038] In the above embodiment, each direct air cooling component also includes a steam exhaust device 15 and a condensate pump 16. The condensate outlet of each surface condenser 21 and the condensate outlet of the air cooling island 6 are respectively connected to the steam exhaust device 15 through a condensate pipeline 17. The condensate pump 16 is arranged between the steam exhaust device 15 and the turbine heat recovery system.

[0039] In the above embodiment, the condensate pipeline 17 between the two exhaust devices 15 is connected and provided with a condensate isolation valve 18, the condensate pipeline 17 is connected with each surface condenser 21, and condensate isolation valves 18 are provided on both sides of the connection between the condensate pipeline 17 and each surface condenser 21. Figure 2 As shown, the two exhaust devices 15 are connected through a condensate pipe 17, wherein the condensate pipe 17 is connected to the two surface condensers 21, that is, two connecting points, the outside of the two connecting points and between the two connecting points are provided with condensate isolation valves 18 (that is, there are three condensate isolation valves 18 in total), so as to adapt to the above three operating conditions. Compared with the structure with multiple condensate pipes 17, this structural setting can simplify the overall structure, facilitate operation, and has good flexibility.

[0040] In the above embodiment, the third control valve 9 includes a first valve 91 and a second valve 92 arranged in parallel, and the second valve 92 is connected in series with the heating network peak-shaving heater 11. When the first valve 91 is opened and the second valve 92 is closed, the heating network peak-shaving heater 11 is not connected to the first circulating water loop. When the first valve 91 is closed and the second valve 92 is opened, the heating network peak-shaving heater 11 is connected to the first circulating water loop to further heat the heating network water supply. Specifically, the opening and closing conditions of the first valve 91 and the second valve 92, that is, the opening degree, can be set according to the needs of the heating network user 1, and the adjustability is good.

[0041] In the above embodiment, the heating network user 1 includes short-distance users and long-distance users arranged in parallel, wherein the heating conditions of the short-distance users and the long-distance users can be adjusted by respectively setting the opening of the control valves, and the long-distance users can also be heated by the heating network peak-shaving heater 11 to ensure the heating needs of the long-distance users, which can be set according to specific circumstances.

[0042] In the above embodiment, the air-cooling island 6 includes at least two air-cooling heat exchangers 61 arranged in parallel, and a first control valve 7 is provided at the inlet of each air-cooling heat exchanger 61. When the air-cooling island 6 is used to cool the exhaust gas of the low-pressure cylinder of the turbine, the number of air-cooling heat exchangers 61 to be opened can be selected according to the specific situation.

[0043] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A steam turbine high back pressure heating and power generation system, characterized in that: It includes heat network users, condenser components, mechanical cooling towers and at least two sets of direct air cooling components. The direct air cooling components include air cooling units, circulating water pumps, air cooling islands and heat network peak load heaters. Each air cooling unit includes a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder. The exhaust pipe of the low-pressure cylinder is connected to the air-cooling island through the first control valve, and the exhaust pipe of the low-pressure cylinder is connected to the condenser assembly through the second control valve, and the condenser assembly and each air-cooling island are connected in parallel; The condenser assembly forms a first circulating water loop with the heat network user through a pipeline provided with a third control valve, and the condenser assembly forms a second circulating water loop with the mechanical cooling tower through a pipeline provided with a fourth control valve. The mechanical cooling tower and the heat network user are connected in parallel, and a circulating water pump is provided on the return pipe side of the condenser assembly; The steam extraction pipe of the intermediate pressure cylinder is connected to the peak-shaving heater of the heat network through the steam extraction regulating valve, and the peak-shaving heater of the heat network can be selectively connected to the first circulating water loop; The condenser assembly includes at least two surface condensers arranged in parallel, and the number of the surface condensers is not less than the number of the direct air cooling assemblies; The number of air-cooling units and surface condensers are both two; The two second control valves are connected via a steam pipeline, the steam pipeline is connected to two surface condensers respectively, and a steam isolation valve is provided between the connection point between the steam pipeline and the two surface condensers.

2. The steam turbine high back pressure heating and power generation system according to claim 1, characterized in that: Each of the direct air-cooling components also includes a steam exhaust device and a condensate pump. The condensate outlet of each surface condenser and the condensate outlet of the air-cooling island are respectively connected to the steam exhaust device through a condensate pipeline. The condensate pump is arranged between the steam exhaust device and the turbine heat recovery system.

3. The steam turbine high back pressure heating and power generation system according to claim 2, characterized in that: The condensate pipeline between the two exhaust devices is connected and is provided with a condensate isolation valve. The condensate pipeline is connected with each of the surface condensers respectively, and the condensate isolation valves are respectively provided on both sides of the connection between the condensate pipeline and each of the surface condensers.

4. The steam turbine high back pressure heating and power generation system according to claim 1, characterized in that: The third control valve includes a first valve and a second valve arranged in parallel, and the second valve is connected in series with the heating network peak-shaving heater.

5. The steam turbine high back pressure heating and power generation system according to claim 4, characterized in that: The heating network users include short-distance users and long-distance users arranged in parallel.

6. The steam turbine high back pressure heating and power generation system according to any one of claims 1 to 5, characterized in that: The air-cooling island includes at least two air-cooling heat exchangers arranged in parallel, and the first control valve is provided at the inlet of each of the air-cooling heat exchangers.

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