Direct air-cooling unit cold end exhaust steam waste heat utilization system combined with absorption heat pump

Abstract

The invention discloses a direct air-cooling unit cold end exhaust steam waste heat utilization system combined with an absorption heat pump, comprising a steam turbine intermediate pressure cylinder, the steam turbine intermediate pressure cylinder is respectively connected to an absorption heat pump and a steam turbine low pressure cylinder through pipelines, an exhaust device is arranged below the steam turbine low pressure cylinder, a heat exchanger is connected to the bottom of the exhaust device, the heat exchanger and the absorption heat pump form a circulation loop through pipelines, the exhaust device side wall is connected to an exhaust pipe, the other end of the exhaust pipe is connected to an air cooling island, an absorption heat pump and a mechanical ventilation tower, the air cooling island is connected to the exhaust device through a condensate pipe, the absorption heat pump is connected to the condensate pipe through a pipe, the absorption heat pump is also connected to a heat network heater through a pipe to form a circulation loop, the heat network heater is also connected to the heat exchanger through a pipe, and the mechanical ventilation tower is also connected to the condensate pipe through a pipe. The invention solves the problem that the exhaust steam waste heat existing in the prior art cannot be effectively recycled and utilized, and the exhaust steam waste heat loss causes a significant reduction in the comprehensive utilization rate of energy.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal power generation, and relates to a direct air-cooling unit cold-end exhaust steam waste heat utilization system combined with an absorption heat pump. Background Art

[0002] Thermal power still ranks first in the energy mix, and air-cooled units account for more than 20% of thermal power units. The water-saving advantage makes them widely built in the arid and water-scarce areas in northwest my country, becoming the mainstay of electricity in these areas. Air-cooled units are mainly divided into two categories, direct air cooling and indirect air cooling. Both types of air-cooled units will eventually release heat to the air, so air-cooled units are severely affected by environmental conditions. Since the areas where direct air-cooled units are located have large temperature fluctuations throughout the year, extremely cold winters and high temperatures in summers, and poor operating conditions, the operating parameters of the units fluctuate widely, problems are prone to occur, and operation and maintenance are difficult.

[0003] At present, the cold end performance degradation phenomenon of steam turbine units using direct air cooling system is common, especially in summer, the units often limit the load increase due to over-temperature operation of fine treatment due to excessive back pressure. The load limit not only leads to a decrease in power plant revenue, but also puts it at risk of grid assessment. At the same time, the main factor affecting the performance of air-cooled units is the loss of cold source at the cold end. The existing methods to improve the performance of direct air-cooled cold ends mainly include adding peak cooling systems, expanding the capacity of air-cooled islands, and using the cooling margin of auxiliary machines to increase peak condensers. No matter which form is used, the exhaust steam waste heat cannot be effectively recycled and utilized, and the loss of exhaust steam waste heat causes a significant reduction in the comprehensive utilization rate of energy. Summary of the invention

[0004] The purpose of the present invention is to provide a direct air-cooling unit cold end exhaust steam waste heat utilization system combined with an absorption heat pump, which solves the problem in the prior art that the exhaust steam waste heat cannot be effectively recovered and utilized, and the loss of exhaust steam waste heat causes a significant reduction in the comprehensive energy utilization rate.

[0005] The technical solution adopted by the present invention is a direct air-cooled unit cold-end exhaust steam waste heat utilization system combined with an absorption heat pump, comprising a steam turbine intermediate-pressure cylinder, the exhaust port of the steam turbine intermediate-pressure cylinder is respectively connected to the absorption heat pump and the steam turbine low-pressure cylinder through pipelines, an exhaust device is arranged below the steam turbine low-pressure cylinder, the bottom of the exhaust device is connected to a heat exchanger through a pipeline, the heat exchanger and the absorption heat pump form a circulation loop through the pipeline, an exhaust pipe is connected to the top of the side wall of the exhaust device, the other end of the exhaust pipe is divided into three paths respectively connected to an air-cooled island, an absorption heat pump and a mechanical ventilation tower, the air-cooled island is also connected to the exhaust device through a condensate pipe, the absorption heat pump is also connected to the condensate pipe through a pipeline, the absorption heat pump is also connected to a heat network heater through a pipeline to form a circulation loop, the heat network heater is also connected to the heat exchanger through a pipeline, and the mechanical ventilation tower is also connected to the condensate pipe through a pipeline.

[0006] The present invention is also characterized in that

[0007] The exhaust gas from the intermediate pressure cylinder of the steam turbine enters the absorption heat pump through a pipeline, flows out of the absorption heat pump, and is connected to the deaerator through a pipeline.

[0008] The heat exchanger is also connected to a heater via a pipeline.

[0009] A condensate pump is provided on the pipeline between the bottom of the exhaust device and the heat exchanger.

[0010] The heat exchanger is connected to the absorption heat pump through pipeline G1. Pipeline G1 is divided into two pipelines G2 and G3 through the absorption heat pump, which are respectively connected to the heat exchanger and the heat network heater. A second circulation pump is arranged on pipeline G1, and a first valve and a second valve are arranged on pipeline G2 and pipeline G3 respectively.

[0011] The absorption heat pump is connected to the condensate pipe via a pipe G4, and a third circulation pump is provided on the pipe G4.

[0012] An exhaust pipe is connected to the top of the side wall of the exhaust device. The other end of the exhaust pipe is divided into three pipes, namely pipe G5, pipe G6, and pipe G7. The other ends of pipe G5, pipe G6, and pipe G7 are respectively connected to the air cooling island, absorption heat pump and mechanical ventilation tower. The fourth valve and the third valve are respectively provided on pipe G6 and pipe G7.

[0013] The mechanical ventilation tower is connected to the condensate pipe through a pipeline G8, and a first circulation pump is arranged on the pipeline G8.

[0014] The heating network heater is connected to the pipeline G1 through the pipeline G9 at a position on the side of the second circulation pump close to the absorption heat pump.

[0015] The beneficial effects of the present invention are:

[0016] The air-cooled unit of the present invention can reduce back pressure in summer conditions and improve the unit's load-bearing capacity in summer. At the same time, the waste heat of exhaust steam is recovered and utilized to heat condensate, thereby reducing the unit's cold source loss and improving the thermal efficiency of the heat recovery system of the condensate system. The air-cooled unit adopts an absorption heat pump waste heat utilization system in winter conditions, and the cold source loss is minimized, which can not only improve the thermal efficiency of the heat recovery system of the condensate system, but also improve the heating capacity of the air-cooled unit. Therefore, this system greatly improves the overall economy and safety of the unit, reduces the pressure of power grid assessment, and maximizes the comprehensive benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the cold-end exhaust steam waste heat utilization system of a direct air-cooling unit combined with an absorption heat pump according to the present invention.

[0018] In the figure, 1. intermediate pressure cylinder of steam turbine, 2. absorption heat pump, 3. low pressure cylinder of steam turbine, 4. exhaust device, 5. heat exchanger, 6. exhaust pipe, 7. first circulation pump, 8. air cooling island, 9. condensate pipe, 10. heating network heater, 11. mechanical ventilation tower, 12. deaerator, 13. heater, 14. condensate pump, 15. second circulation pump, 16. first valve, 17. second valve, 18. third circulation pump, 19. fourth valve, 20. third valve. DETAILED DESCRIPTION

[0019] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] The present invention is combined with an absorption heat pump direct air cooling unit cold end exhaust steam waste heat utilization system, the structure of which is as follows Figure 1 As shown, it includes a steam turbine intermediate pressure cylinder 1, the exhaust port of the steam turbine intermediate pressure cylinder 1 is connected to the absorption heat pump 2 and the steam turbine low pressure cylinder 3 through pipelines, an exhaust device 4 is arranged below the steam turbine low pressure cylinder 3, the bottom of the exhaust device 4 is connected to the heat exchanger 5 through a pipeline, the heat exchanger 5 and the absorption heat pump 2 form a circulation loop through the pipeline, an exhaust pipe 6 is connected to the upper side wall of the exhaust device 4, the other end of the exhaust pipe 6 is divided into three paths respectively connected to the air cooling island 8, the absorption heat pump 2 and the mechanical ventilation tower 11, the air cooling island 8 is also connected to the exhaust device 4 through a condensate pipe 9, the absorption heat pump 2 is also connected to the condensate pipe 9 through a pipeline, the absorption heat pump 2 is also connected to the heat network heater 10 through a pipeline to form a circulation loop, the heat network heater 10 is also connected to the heat exchanger 5 through a pipeline, and the mechanical ventilation tower 11 is also connected to the condensate pipe 9 through a pipeline.

[0021] The exhaust gas from the intermediate pressure cylinder 1 of the steam turbine enters the absorption heat pump 2 through a pipeline, flows out through the absorption heat pump 2, and is connected to the deaerator 12 through a pipeline.

[0022] The heat exchanger 5 is also connected to a heater 13 via a pipeline.

[0023] A condensate pump 14 is provided on the pipeline between the bottom of the exhaust device 4 and the heat exchanger 5 .

[0024] The heat exchanger 5 is connected to the absorption heat pump 2 through the pipeline G1. After passing through the absorption heat pump 2, the pipeline G1 is divided into two pipelines G2 and G3, which are respectively connected to the heat exchanger 5 and the heat network heater 10. A second circulation pump 15 is arranged on the pipeline G1, and a first valve 16 and a second valve 17 are respectively arranged on the pipeline G2 and the pipeline G3.

[0025] The absorption heat pump 2 is connected to the condensate pipe 9 via a pipe G4, and a third circulation pump 18 is provided on the pipe G4.

[0026] The exhaust pipe 6 is connected to the upper side wall of the exhaust device 4. The other end of the exhaust pipe 6 is divided into three pipes, namely pipe G5, pipe G6, and pipe G7. The other ends of pipe G5, pipe G6, and pipe G7 are respectively connected to the air cooling island 8, the absorption heat pump 2, and the mechanical ventilation tower 11. The fourth valve 19 and the third valve 20 are respectively provided on the pipe G6 and the pipe G7.

[0027] The mechanical ventilation tower 11 is connected to the condensate pipe 9 via a pipeline G8, and a first circulation pump 7 is provided on the pipeline G8.

[0028] The heating network heater 10 is connected to the pipeline G1 at a position on the side of the second circulation pump 15 close to the absorption heat pump 2 through the pipeline G9.

[0029] The working process of the present invention is:

[0030] In the summer operation of the air-cooling unit, the second valve 17 is closed and the heating network heater 10 is not put into use. Part of the exhaust steam from the intermediate pressure cylinder 1 of the steam turbine flows to the low pressure cylinder 3 of the steam turbine, and the other part flows to the absorption heat pump 2 as the intermediate exhaust steam, and serves as the driving steam of the absorption heat pump 2. After passing through the absorption heat pump 2, it becomes a steam drain and flows to the deaerator 12; the low pressure cylinder 3 of the steam turbine exhausts steam to the upper exhaust device 4, and the exhaust steam is divided into three parts through the exhaust pipe 6. The first part of the exhaust steam flows to the absorption heat pump 2 through the fourth valve 19, and serves as the low temperature heat source of the absorption heat pump 2. After cooling, it flows to the third circulating pump 18 and then flows to the condensate pipe 9. The flow rate of this part of the exhaust steam needs to be heat matched with the flow rate of the condensate; the second part of the exhaust steam flows to the mechanical ventilation tower 11 through the third valve 20, and becomes condensate after cooling, and flows to the condensate pipe 9 through the first circulating pump 7; the third part of the exhaust steam flows to the air cooling island 8, and flows to the condensate pipe 9 after cooling; the cold end back pressure can be adjusted by adjusting the flow rate of the second part of the exhaust steam. The circulating water of the absorption heat pump 2 flows to the heat exchanger 5 through the first valve 16 to heat the condensed water. After the circulating water flows through the heat exchanger 5, it flows back to the absorption heat pump 2 through the second circulating pump 15. The condensed water flows to the heat exchanger 5 through the condensed water pump 14, and flows to the low-temperature heater 13 after being heated.

[0031] In winter operation of air-cooled units, the third valve 20 is closed and the mechanical ventilation tower 11 is not put into use. Part of the exhaust steam from the intermediate pressure cylinder 1 of the steam turbine flows to the low pressure cylinder 3 of the steam turbine, and the other part flows to the absorption heat pump 2 as the intermediate exhaust steam, and serves as the driving steam of the absorption heat pump 2. After passing through the absorption heat pump 2, it becomes a steam drain and flows to the deaerator 12; the low pressure cylinder 3 of the steam turbine exhausts steam to the upper exhaust device 4, and the exhaust steam is divided into two parts through the exhaust pipe 6. The first part of the exhaust steam flows to the absorption heat pump 2 through the fourth valve 19, and serves as the low temperature heat source of the absorption heat pump 2. After cooling, it flows to the third circulation pump 18 and then to the condensate pipe 9. This part of the exhaust steam flow needs to be heat matched with the condensate flow and the heat network water flow; the second part of the exhaust steam flows to the air cooling island 8, and flows to the condensate pipe 9 after cooling. The circulating water of the absorption heat pump 2 is divided into two parts. One part of the circulating water flows to the heat exchanger 5 through the first valve 16 to heat the condensed water. After passing through the heat exchanger, the circulating water flows back to the absorption heat pump through the circulating pump 2; the other part of the circulating water flows to the heating network heater through the valve 2, heats the heating network water, flows to the second circulating pump 15 and flows back to the absorption heat pump 2. The heating network water is heated by the heating network heater and flows to the peak heating network heater. The condensed water flows to the heat exchanger 5 through the condensed water pump 14, and flows to the low-temperature heater after being heated.

[0032] The present invention combines the cold-end exhaust steam waste heat utilization system of the direct air-cooled unit with an absorption heat pump. The air-cooled unit can reduce the back pressure in summer conditions and improve the unit's summer load-bearing capacity. At the same time, the exhaust steam waste heat is recovered and utilized to heat condensate, thereby reducing the unit's cold source loss and improving the thermal efficiency of the heat recovery system of the condensate system. The air-cooled unit adopts the absorption heat pump waste heat utilization system in winter conditions, and the cold source loss is minimized, which can not only improve the thermal efficiency of the heat recovery system of the condensate system, but also improve the heating capacity of the air-cooled unit. Therefore, this system greatly improves the overall economy and safety of the unit, reduces the assessment pressure of the power grid, and maximizes the comprehensive benefits.

Claims

1. A direct air-cooling unit cold end exhaust steam waste heat utilization system combined with an absorption heat pump, characterized in that: The invention comprises a steam turbine intermediate pressure cylinder (1), wherein the exhaust port of the steam turbine intermediate pressure cylinder (1) is connected to an absorption heat pump (2) and a steam turbine low pressure cylinder (3) through pipelines, respectively; an exhaust device (4) is arranged below the steam turbine low pressure cylinder (3); the bottom of the exhaust device (4) is connected to a heat exchanger (5) through a pipeline; the heat exchanger (5) and the absorption heat pump (2) form a circulation loop through the pipeline; an exhaust pipe (6) is connected to the top of the side wall of the exhaust device (4); the other end of the exhaust pipe (6) is divided into three paths respectively connected to An air-cooling island (8), an absorption heat pump (2) and a mechanical ventilation tower (11) are connected; the air-cooling island (8) is also connected to the exhaust device (4) via a condensate pipe (9); the absorption heat pump (2) is also connected to the condensate pipe (9) via a pipeline; the absorption heat pump (2) is also connected to a heat network heater (10) via a pipeline to form a circulation loop; the heat network heater (10) is also connected to the heat exchanger (5) via a pipeline; and the mechanical ventilation tower (11) is also connected to the condensate pipe (9) via a pipeline; The heat exchanger (5) is connected to the absorption heat pump (2) via a pipeline G1, and the pipeline G1 is divided into two pipelines G2 and G3 through the absorption heat pump (2), which are respectively connected to the heat exchanger (5) and the heat network heater (10), and a second circulation pump (15) is provided on the pipeline G1, and a first valve (16) and a second valve (17) are provided on the pipeline G2 and the pipeline G3 respectively; The heating network heater (10) is connected to the pipeline G1 via the pipeline G9 at a position on the side of the second circulation pump (15) close to the absorption heat pump (2).

2. The direct air cooling unit cold end exhaust steam waste heat utilization system combined with an absorption heat pump according to claim 1 is characterized in that: The exhaust gas of the steam turbine intermediate pressure cylinder (1) enters the absorption heat pump (2) through a pipeline, then flows out of the absorption heat pump (2) and is connected to the deaerator (12) through a pipeline.

3. The direct air cooling unit cold end exhaust steam waste heat utilization system combined with an absorption heat pump according to claim 1, characterized in that: The heat exchanger (5) is also connected to a heater (13) via a pipeline.

4. The direct air cooling unit cold end exhaust steam waste heat utilization system combined with an absorption heat pump according to claim 1, characterized in that: A condensate pump (14) is provided on the pipeline between the bottom of the steam exhaust device (4) and the heat exchanger (5).

5. The direct air cooling unit cold end exhaust steam waste heat utilization system combined with an absorption heat pump according to claim 1, characterized in that: The absorption heat pump (2) is connected to the condensate water pipe (9) via a pipeline, and a third circulation pump (18) is provided on the pipeline between the absorption heat pump (2) and the condensate water pipe (9).

6. The direct air cooling unit cold end exhaust steam waste heat utilization system combined with an absorption heat pump according to claim 5, characterized in that: The exhaust pipe (6) is connected to the upper side wall of the exhaust device (4); the other end of the exhaust pipe (6) is divided into three pipes, namely pipe G5, pipe G6 and pipe G7; the other ends of the pipes G5, G6 and G7 are respectively connected to the air cooling island (8), the absorption heat pump (2) and the mechanical ventilation tower (11); the pipes G6 and G7 are respectively provided with a fourth valve (19) and a third valve (20).

7. The direct air cooling unit cold end exhaust steam waste heat utilization system combined with an absorption heat pump according to claim 1, characterized in that: The mechanical ventilation tower (11) is connected to the condensate pipe (9) via a pipeline G8, and a first circulation pump (7) is provided on the pipeline G8.

Images