A power station circulating water waste heat system

Abstract

The present invention discloses a power plant circulating water waste heat system, comprising: a condensing steam turbine with a generator, a condenser, a condensate pump, a circulating water pump, a suction well, a cooling tower, a heat pump system, an ORC system, and an expander with a permanent magnet motor. The above components are connected through a pipeline system to form a power plant circulating water waste heat system combining the heat pump system and the ORC system. The power plant circulating water waste heat system formed by combining the heat pump system and the ORC system not only solves the loss caused by the increase in the evaporation amount of the circulating water due to the rise in the circulating water temperature, but also reduces the temperature of the circulating water, improves the vacuum of the condenser, and also utilizes the waste heat of the circulating water to generate electricity, generating additional economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power generation, and particularly to a waste heat system for circulating water in a power station. Background Art

[0002] During the thermal power generation process in a power plant, after the steam does work in a condensing steam turbine, it becomes low-temperature steam and is discharged into the condenser for condensation and heat release. This part of the condensation heat is carried by the circulating water to the cooling tower and directly discharged into the atmosphere. The circulating water plays a role in maintaining the vacuum in the condenser and cooling the condensate in the overall unit cycle. However, due to the presence of non-condensable gases, the vacuum degree in the condenser decreases, and the temperature of the circulating water rises, especially in summer. Cooling through the cooling tower increases the evaporation rate of the circulating water, resulting in the largest makeup water volume, high water resource consumption, more load limit situations, and a high energy waste rate.

[0003] In order to reduce the energy waste rate, some enterprises have proposed waste heat recovery devices for circulating water. For example, a Chinese invention patent application with the patent application number 202122463045.0 discloses a waste heat recovery device for circulating water in a thermal power plant, including a box body. A hot water tank is fixedly installed on the top of the box body. An intake pipe is installed on one side of the box body. A delivery pipe is fixed between the top of the box body and the hot water tank. A heat conduction pipe is installed in the hot water tank. One end of the delivery pipe is connected to the heat conduction pipe. A hot gas discharge pipe is installed on the top of the hot water tank. The end of the heat conduction pipe away from the delivery pipe is connected to the hot gas discharge pipe. A piston is slidably installed in the box body. A check valve one is installed on the intake pipe. A check valve two is installed on the delivery pipe. A filter screen is installed at one end of the box body. A cleaning component for the filter screen is provided on the box body. A discharge port is opened at the bottom of the box body. A cover plate is connected to the discharge port by bolts. The discharge port is located below the filter screen and close to the intake pipe. During operation, circulating water is introduced into the hot water tank through a hot water pipe on one side of the hot water tank. The servo motor is started to drive the reciprocating lead screw one to rotate, driving the reciprocating plate to move back and forth and driving the connecting rod to move, so that the piston moves back and forth. When the piston moves towards the reciprocating lead screw, the intake pipe sucks in external air flow into the box body. The check valve one restricts the air flow to only enter the intake pipe from the outside. When the piston moves in the direction away from the reciprocating lead screw one, it pushes the air flow in the box body to be discharged into the heat conduction pipe through the delivery pipe. The check valve two restricts the air flow to only flow from the box body to the delivery pipe. The air flow enters the heat conduction pipe and exchanges heat with the circulating hot water outside the heat conduction pipe to preheat the air flow. The hot air flow is discharged through the hot gas discharge pipe and can be used for preheating the heating supply, reducing the consumption of the heating supply, recovering the waste heat of the circulating water, and improving the heat utilization rate.

[0004] However, due to seasonal limitations, this solution can only be used during the heating season. During the non - heating season, the system will stop operating, and the waste heat of the circulating water will still be discharged into the atmosphere, resulting in energy waste. In addition, due to the climate differences between the north and the south, in the south where there is no heating throughout the year, the utilization rate of the waste heat of the circulating water is basically zero. In the north, heating is only required in winter, and there is no need for heating in other seasons, so the utilization rate of the waste heat of the circulating water is not very high, and the energy waste rate is still relatively high. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a waste heat recovery system for power plant circulating water that combines a heat pump system and an ORC system. This system uses the heat pump system to absorb the waste heat of the circulating water to generate hot water, which is used as the heat source for the ORC system to generate electricity. It can effectively reduce the temperature of the circulating water, improve the vacuum degree of the condenser, save water resource consumption, increase additional power generation, and improve the overall efficiency of the unit.

[0006] To solve the problem of high energy waste rate, the technical solution adopted by the present invention is to effectively utilize the waste heat of the circulating water by combining a heat pump system and an ORC system to improve the energy utilization rate. A waste heat recovery system for power plant circulating water includes: a condensing steam turbine with a generator, a condenser, a condensate pump, a circulating water pump, a sump, a cooling tower, a heat pump system, an ORC system, and an expander with a permanent magnet motor. Among them, the condensing steam turbine doing external work to make the generator operate to generate current, and the expander doing external work to make the permanent magnet motor operate to generate current are both existing mature technologies. Therefore, the connection structure between the condensing steam turbine and the generator, and the connection structure between the expander and the permanent magnet motor will not be elaborated here.

[0007] The specific connection relationships among the components are as follows: The exhaust steam outlet of the condensing steam turbine is connected to the steam inlet of the condenser through the first pipeline. At the condensate outlet of the condenser, there is a second pipeline with a condensate pump connected, and the second pipeline converges and is connected to the third pipeline. The water outlet of the sump is connected to the cooling water inlet of the condenser through the first circulation pipeline with a circulating pump. The cooling water outlet of the condenser is connected to the second circulation pipeline, the outlet of the second circulation pipeline is connected to the inlet of the cooling tower, and the outlet of the cooling tower is connected to the inlet of the sump through the third circulation pipeline. The low-pressure saturated steam outlet of the condensing steam turbine is connected to the saturated steam inlet of the heat pump system through the fourth pipeline, and the condensate outlet of the heat pump system is connected to the third pipeline through the fifth pipeline. There is a fourth circulation pipeline provided on the second circulation pipeline, and the outlet of the fourth circulation pipeline is connected to the circulating water inlet of the heat pump system. The circulating water outlet of the heat pump system is connected to the third circulation pipeline through the fifth circulation pipeline. The cold water inlet of the heat pump system is connected to the cold water outlet of the ORC system through the sixth pipeline, and the water outlet of the heating user return water pipe is connected to the sixth pipeline. The hot water outlet of the heat pump system is connected to the hot water inlet of the ORC system through the seventh pipeline, and the water inlet of the heating user supply water pipe is connected to the seventh pipeline. The working medium steam outlet of the ORC system is connected to the gas inlet of the expander through the eighth pipeline, and the liquid outlet of the expander is connected to the working medium liquid inlet of the ORC system through the ninth pipeline. At least one valve is installed respectively on the second pipeline, the third pipeline, the fourth pipeline, the fifth pipeline, the sixth pipeline, the seventh pipeline between the connection of the heating user supply water pipe and the outlet of the seventh pipeline, the heating user supply water pipe, the eighth pipeline, the ninth pipeline, the first circulation pipeline, and the second circulation pipeline.

[0008] The heat pump system uses high-grade thermal energy as power, recovers the heat of the low-temperature heat source, and produces hot water at a relatively high temperature for heating or meeting process requirements, etc. The specific structure of the heat pump system in this solution includes: a first condenser, a generator, a heat exchanger, an absorber, and a first evaporator; the steam inlet of the generator is the saturated steam inlet of the heat pump system, and a first heat pump system pipeline with a condensate pump is connected to the condensate outlet of the generator. The outlet of the first heat pump system pipeline is the condensate outlet of the heat pump system. The refrigerant vapor outlet of the generator is connected to the refrigerant vapor inlet of the first condenser through a second heat pump system pipeline. The concentrated refrigerant solution outlet of the generator is connected to the concentrated refrigerant inlet of the heat exchanger through a third heat pump system pipeline. The concentrated refrigerant outlet of the heat exchanger is connected to the spray pipe inlet of the absorber through a fourth heat pump system pipeline. The diluted refrigerant outlet of the heat exchanger is connected to the diluted refrigerant solution inlet of the generator through a fifth heat pump system pipeline; the low-temperature refrigerant vapor inlet of the absorber is connected to the low-temperature refrigerant vapor outlet of the first evaporator through a sixth heat pump system pipeline. The diluted refrigerant solution outlet of the absorber is connected to the diluted refrigerant inlet of the heat exchanger through a seventh heat pump system pipeline with a solution pump. The cold water inlet of the absorber is the cold water inlet of the heat pump system. The hot water outlet of the absorber is connected to the water inlet of the first condenser through an eighth heat pump system pipeline; the refrigerant solution outlet of the first evaporator is connected to the spray pipe inlet of the first evaporator through a ninth heat pump system pipeline with a first working fluid pump. The circulating water inlet of the first evaporator is the circulating water inlet of the heat pump system. The circulating water outlet of the first evaporator is the circulating water outlet of the heat pump system; the refrigerant solution outlet of the first condenser is connected to the refrigerant solution inlet on the first evaporator through a tenth heat pump system pipeline with a throttle valve. The hot water outlet of the first condenser is the hot water outlet of the heat pump system.

[0009] Furthermore, in the aforementioned waste heat system of power station circulating water, a water storage tank is provided on the first heat pump system pipeline between the condensate outlet of the generator and the condensate pump. During actual use, when it is necessary to supplement refrigerant to the heat pump system, a refrigerant storage tank can be provided on the ninth heat pump system pipeline between the refrigerant solution outlet of the first evaporator and the first working fluid pump. The purpose of supplementing refrigerant to the heat pump system is achieved by adding refrigerant to the refrigerant storage tank.

[0010] The Organic Rankine Cycle (ORC for short) is a Rankine cycle that uses low-boiling organic substances as the working fluid. The specific structure of the ORC system in this solution includes: a second evaporator, a second condenser, and a liquid storage tank; at the hot water inlet of the second evaporator, there is a first ORC system pipeline with a hot water pump connected. The inlet of the first ORC system pipeline is the hot water inlet of the ORC system. The cold water outlet of the second evaporator is the cold water outlet of the ORC system. The working fluid steam outlet of the second evaporator is the working fluid steam outlet of the ORC system. The working fluid solution inlet of the second evaporator is connected to the outlet of the liquid storage tank through a second ORC system pipeline with a second working fluid pump. The inlet of the liquid storage tank is connected to the working fluid outlet of the second condenser through a third ORC system pipeline. The working fluid inlet of the second condenser is the working fluid liquid inlet of the ORC system. An air inlet and an air outlet are also provided on the second condenser. At the air inlet of the second condenser, there is a fourth ORC system pipeline with a fan connected. The fan continuously inputs external air into the second condenser to cool the working fluid solution entering the second condenser by air cooling.

[0011] The beneficial effects of the present invention are as follows: The power station circulating water waste heat system composed of the heat pump system and the ORC system not only solves the loss caused by the increase in the circulating water evaporation amount due to the rise in the circulating water temperature, but also reduces the temperature of the circulating water, improves the vacuum of the condenser, and generates additional economic benefits by using the waste heat of the circulating water for power generation. Description of the Drawings

[0012] Figure 1 It is a schematic flow diagram of a power station circulating water waste heat system described in the present invention.

[0013] Figure 2 It is Figure 1 A partial enlarged schematic flow diagram of the connection relationship between the condensing steam turbine with a generator, the condenser, the condensate pump, the circulating water pump, and the sump in

[0014] Figure 3 It is Figure 1 A partial enlarged schematic flow diagram of the connection relationship between the condensing steam turbine with a generator, the cooling tower, and the heat pump system in

[0015] Figure 4 It is Figure 1 A partial enlarged schematic flow diagram of the connection relationship between the heat pump system, the ORC system, and the expander with a permanent magnet motor in

[0016] Figure 5 It is a schematic flow diagram of the heat pump system.

[0017] Figure 6 It is Figure 5 A partial enlarged schematic flow diagram of the left half part.

[0018] Figure 7 is Figure 5 A partial enlarged process schematic diagram of the right half part.

[0019] Figure 8 It is a process schematic diagram of another embodiment of the heat pump system.

[0020] Figure 9 It is a process schematic diagram of the ORC system. Specific embodiments

[0021] The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0022] Embodiment 1

[0023] As Figure 1 , Figure 2 , Figure 3 and Figure 4 shown, a power plant circulating water waste heat system described in the present embodiment of the new type includes: a condensing steam turbine 11 with a generator 12, a condenser 13, a condensate pump 14, a circulating water pump 15, a sump 16, a cooling tower 18, a heat pump system 17, an ORC system 19, and an expander 20 with a permanent magnet motor 21. Among them, the heat pump system 17 uses high-grade heat energy as power to recover the heat of the low-temperature heat source and produce hot water at a higher temperature for heating or meeting process requirements. The Organic Rankine Cycle (ORC) is a Rankine cycle using low-boiling organic substances as the working fluid.

[0024] The above components are connected through a pipeline system to form a combined power plant circulating water waste heat system of the heat pump system and the ORC system. The specific connection relationship of the pipeline system is:

[0025] The exhaust steam 111 of the condensing steam turbine 11 is communicated with the steam inlet 131 of the condenser 13 through the first pipeline 31. A second pipeline 32 with a condensate pump 14 is connected at the condensate outlet 132 of the condenser 13, and the second pipeline 32 converges and is communicated with the third pipeline 33. The water outlet 161 of the sump 16 is communicated with the cooling water inlet 133 of the condenser 13 through the first circulation pipeline 41 with a circulating pump 15. The cooling water outlet 134 of the condenser 13 is communicated with the second circulation pipeline 42. The outlet of the second circulation pipeline 42 is communicated with the water inlet 181 of the cooling tower 18. The water outlet 182 of the cooling tower 18 is communicated with the water inlet 162 of the sump 16 through the third circulation pipeline 43. The low-pressure saturated steam outlet 112 of the condensing steam turbine 12 is communicated with the saturated steam inlet 171 of the heat pump system 17 through the fourth pipeline 34. The condensate outlet 172 of the heat pump system 17 is connected to the third pipeline 33 through the fifth pipeline 35. A fourth circulation pipeline 44 is provided on the second circulation pipeline 42, and the outlet of the fourth circulation pipeline 44 is communicated with the circulating water inlet 173 of the heat pump system 17. The circulating water outlet 174 of the heat pump system 17 is connected to the third circulation pipeline 43 through the fifth circulation pipeline 45. The cold water inlet 175 of the heat pump system 17 is communicated with the cold water outlet 191 of the ORC system 19 through the sixth pipeline 36. The water outlet of the heating user return pipe 47 is connected to the sixth pipeline 36. The hot water outlet 176 of the heat pump system 17 is communicated with the hot water inlet 192 of the ORC system 19 through the seventh pipeline 37. The water inlet of the heating user supply pipe 46 is connected to the seventh pipeline 37. The working fluid steam outlet 193 of the ORC system 19 is communicated with the gas inlet 201 of the expander 20 through the eighth pipeline 38. The liquid outlet 202 of the expander 20 is communicated with the working fluid liquid inlet 194 of the ORC system 19 through the ninth pipeline 39.

[0026] To facilitate the control of the on-off of each pipeline in the pipeline system, in this embodiment, at least one valve is installed respectively on the second pipeline 32, the third pipeline 33, the fourth pipeline 34, the fifth pipeline 35, the sixth pipeline 36, the section of the seventh pipeline 37 between the connection of the heating user supply pipe 46 and the outlet of the seventh pipeline 37, the heating user supply pipe 46, the eighth pipeline 38, the ninth pipeline 39, the first circulation pipeline 41, and the second circulation pipeline 42. The selection of each valve on the above-mentioned each pipeline is determined according to actual needs, and the specific models and types of the valves are not limited here.

[0027] The circulating water circulation route is as follows: The water flowing out from the circulating water outlet 174 of the heat pump system 17 and the water flowing out from the water outlet 182 of the cooling tower 18 converge and enter the suction well 16. The water in the suction well 16 is pumped into the condenser 13 by the circulating water pump 15. After indirectly exchanging heat and absorbing heat with the low-temperature and low-pressure steam entering the condenser 13, it flows out from the cooling water outlet 134 of the condenser 13 into the second circulation pipeline 42. The second circulation pipeline 42 is divided into two paths: one path flows back into the cooling tower 18 for cooling, and one path flows into the circulating water inlet 173 of the heat pump system 17 through the fourth circulation pipeline 44 and serves as a heat source for the heat pump system 7.

[0028] The low-temperature and low-pressure steam route of the condensing steam turbine 11 is as follows: The low-temperature and low-pressure steam enters the condenser 13 through the exhaust outlet 111 of the condensing steam turbine 11, the first pipeline 31, and the steam inlet 131 of the condenser 13. After indirectly exchanging heat and releasing heat with the circulating water entering the condenser 13, it flows out from the condensate outlet 132 of the condenser 13 and is transported outward to the area where the boiler is located through the third pipeline 33.

[0029] When the system is mainly for heating, the low-temperature saturated steam of the condensing steam turbine 11 enters the heat pump system 17 through the low-temperature saturated steam outlet 112 of the condensing steam turbine 11, the fourth pipeline 34, and the saturated steam inlet 171 of the heat pump system 17. After heating the water entering the heat pump system 17 from the heating user return pipe 47 and the sixth pipeline 36, it is transported outward to the area where the boiler is located through the condensate outlet 172 of the heat pump system 17, the fifth pipeline 35, and the third pipeline 33. The water entering the heat pump system 17 absorbs heat and is transported outward to the heating users through the hot water outlet 176 of the heat pump system 17, the seventh pipeline 37, and the heating user supply pipe 46.

[0030] When the system is mainly for power generation, the low-temperature saturated steam of the condensing steam turbine 11 enters the heat pump system 17 through the low-temperature saturated steam outlet 112 of the condensing steam turbine 11, the fourth pipeline 34, and the saturated steam inlet 171 of the heat pump system 17. After heating the water entering the heat pump system 17 from the heating user return pipe 47 and the sixth pipeline 36, it is transported outward to the area where the boiler is located through the condensate outlet 172 of the heat pump system 17, the fifth pipeline 35, and the third pipeline 33. The water entering the heat pump system 17 absorbs heat and enters the ORC system 19 through the hot water outlet 176 of the heat pump system 17, the seventh pipeline 37, and the hot water inlet 192 of the ORC system 19, serving as the heat source for the ORC system 19 to drive the expander 20.

[0031] In summary, the overall process route of the system is that the condensing steam turbine 11 extracts air as the driving heat source of the heat pump system 17, absorbs the heat of the circulating water to generate hot water for winter heating or ORC system power generation. The ORC system uses the hot water generated by the heat pump system 17 as a heat source to complete the system cycle, drive the expander 20 to rotate, and then drive the permanent magnet motor 21 to generate electricity, completing the process flow of the entire system.

[0032] When the power station circulating water waste heat system composed of the above-mentioned heat pump system 17 and the ORC system 19 is applied to the southern occasions where there is no heating throughout the year, the system is mainly used for power generation, and the electric energy generated by the generator 12 and the permanent magnet motor 21 can be fully incorporated into the power grid, or partially incorporated into the power grid and partially used for other purposes. When the power station circulating water waste heat system composed of the above-mentioned heat pump system 17 and the ORC system 19 is applied to the northern occasions where heating is required in winter and no heating is required in other seasons, when it is in winter, the system is mainly used for heating, at this time, the heat pump system 17 is the main system for heating, and the ORC system 19 only maintains the minimum load operation, that is, to meet the power consumption of its own pump. When it is in the season when heating is not required, the system is mainly used for power generation, and the heat pump system 17 and the ORC system 19 work together. The hot water generated by the heat pump system 17 absorbing the heat energy of the circulating water is used as the heat source of the ORC system 19, and the expander 20 works to make the permanent magnet motor 21 generate electric energy.

[0033] The power plant circulating water waste heat system jointly constituted by the heat pump system 17 and the ORC system 19 not only solves the loss caused by the increase in circulating water temperature leading to the increase in circulating water evaporation, but also reduces the temperature of the circulating water, increases the vacuum of the condenser 13, and uses the circulating water waste heat to generate electricity, generating additional economic benefits.

[0034] Embodiment 2

[0035] This embodiment is based on the second embodiment and further describes the heat pump system 17. Figure 5 , Figure 6 and Figure 7 As shown, the specific structure of the heat pump system 17 described in this embodiment includes: a first condenser 55, a generator 51, a heat exchanger 52, an absorber 53, and a first evaporator 54.

[0036] The steam inlet 511 of the generator 51 is the saturated steam inlet 171 of the heat pump system 17. A first heat pump system pipeline 61 with a condensate pump 56 is connected at the condensate outlet 512 of the generator 51, and the outlet of the first heat pump system pipeline 61 is the condensate outlet 172 of the heat pump system 17. The refrigerant vapor outlet 513 of the generator 51 is communicated with the refrigerant vapor inlet 551 of the first condenser 55 through a second heat pump system pipeline 62. The concentrated refrigerant solution outlet 512 of the generator 51 is communicated with the concentrated refrigerant inlet 521 of the heat exchanger 52 through a third heat pump system pipeline 63. The concentrated refrigerant outlet 522 of the heat exchanger 52 is communicated with the spray pipe inlet 531 of the absorber 53 through a fourth heat pump system pipeline 64. The diluted refrigerant outlet 523 of the heat exchanger 52 is communicated with the diluted refrigerant solution inlet 515 of the generator 51 through a fifth heat pump system pipeline 65. The low-temperature refrigerant vapor inlet 532 of the absorber 53 is communicated with the low-temperature refrigerant vapor outlet 541 of the first evaporator 54 through a sixth heat pump system pipeline 66. The diluted refrigerant solution outlet 533 of the absorber 53 is communicated with the diluted refrigerant inlet 524 of the heat exchanger 52 through a seventh heat pump system pipeline 67 with a solution pump 58. The cold water inlet 534 of the absorber 53 is the cold water inlet 175 of the heat pump system 17. The hot water outlet 535 of the absorber 53 is communicated with the water inlet 552 of the first condenser 55 through an eighth heat pump system pipeline 68. The refrigerant solution outlet 546 of the first evaporator 54 is communicated with the refrigerant solution inlet 542 of the spray pipe of the first evaporator 54 through a ninth heat pump system pipeline 69 with a first working medium pump 57. The circulating water inlet 543 of the first evaporator 54 is the circulating water inlet 173 of the heat pump system 17. The circulating water outlet 544 of the first evaporator 54 is the circulating water outlet 174 of the heat pump system 17. The refrigerant solution outlet 553 of the first condenser 55 is communicated with the refrigerant solution inlet 545 on the first evaporator 54 through a tenth heat pump system pipeline 610 with a throttle valve 59. The hot water outlet 554 of the first condenser 55 is the hot water outlet 176 of the heat pump system 17.

[0037] The saturated steam enters the generator 51 through the steam outlet 112 of the saturated condensing steam turbine 11, the fourth pipeline 34, and the steam inlet 511 of the generator 51. After releasing heat through indirect heat exchange with the refrigerant solution in the generator 51, it is output through the condensate pump 56 and the first heat pump system pipeline 61.

[0038] The refrigerant solution in the generator 51 absorbs heat through indirect heat exchange with the saturated steam entering the generator 51, generating refrigerant vapor. The refrigerant vapor enters the first condenser 55 through the refrigerant vapor outlet 513 of the generator 51, the second heat pump system pipeline 62, and the refrigerant vapor inlet 551 of the first condenser 55. At this time, the refrigerant solution in the generator 51 becomes a concentrated refrigerant solution due to partial evaporation. The concentrated refrigerant solution enters the heat exchanger 52 through the concentrated refrigerant solution outlet 512 of the generator 51, the third heat pump system pipeline 63, and the concentrated refrigerant inlet 521 of the heat exchanger 52. After indirect heat exchange with the diluted refrigerant solution entering the heat exchanger 52, it passes through the concentrated refrigerant outlet 522 of the heat exchanger 52, the fourth heat pump system pipeline 64, and the spray pipe inlet 531 of the absorber 53 to enter the spray pipe of the absorber 53. The concentrated refrigerant solution sprayed from the spray pipe of the absorber 53 and the low-temperature refrigerant vapor entering through the low-temperature refrigerant vapor inlet 532 of the absorber 53 together undergo indirect heat exchange with the cold water entering the absorber 53 to form a diluted refrigerant solution. The diluted refrigerant solution, under the action of the solution pump 58, enters the heat exchanger 52 through the diluted refrigerant solution outlet 533 of the absorber 53, the seventh heat pump system pipeline 67, and the diluted refrigerant inlet 524 of the heat exchanger 52. After indirect heat exchange with the concentrated refrigerant solution entering the heat exchanger 52, it returns to the generator 51 through the diluted refrigerant outlet 523 of the heat exchanger 52, the fifth heat pump system pipeline 65, and the diluted refrigerant solution inlet 515 of the generator 51.

[0039] The cold water entering the absorber 53 through the cold water inlet 534 of the absorber 53 absorbs heat through indirect heat exchange with the concentrated refrigerant solution sprayed from the spray pipe of the absorber 53 and the low-temperature refrigerant vapor entering through the low-temperature refrigerant vapor inlet 532 of the absorber 53, and then enters the first condenser 55 through the hot water outlet 535 of the absorber 53, the eighth heat pump system pipeline 68, and the water inlet 552 of the first condenser 55. After absorbing heat through indirect heat exchange with the refrigerant vapor entering the first condenser 55 through the refrigerant vapor outlet 513 of the generator 51, the second heat pump system pipeline 62, and the refrigerant vapor inlet 551 of the first condenser 55, it is output from the hot water outlet 554 of the first condenser 55.

[0040] The refrigerant vapor entering the first condenser 55 exchanges heat indirectly with the water entering the first condenser 55 through the water inlet 552 of the first condenser 55 and releases heat to form a refrigerant solution. The refrigerant solution enters the first evaporator 54 through the refrigerant solution outlet 553 of the first condenser 55, the tenth heat pump system pipeline 610, and the refrigerant gas solution inlet 545 on the first evaporator 54. The circulating water enters the first evaporator 54 through the circulating water inlet 543 of the first evaporator 54, exchanges heat indirectly with the refrigerant solution sprayed from the spray pipe of the first evaporator 54 and the refrigerant solution in the first evaporator 54, and releases heat, and then is output from the circulating water outlet 544 of the first evaporator 54. A part of the refrigerant solution that absorbs heat by indirectly exchanging heat with the circulating water entering the first evaporator 54 through the circulating water inlet 543 of the first evaporator 54 evaporates to form refrigerant vapor. The refrigerant vapor enters the absorber 53 through the low-temperature refrigerant vapor outlet 541 of the first evaporator 54 and the low-temperature refrigerant vapor inlet 532 of the absorber 53.

[0041] In this process, the low-temperature refrigerant solution output from the refrigerant solution outlet 553 of the first condenser 55 enters the first evaporator 54, absorbs heat and evaporates to form low-temperature refrigerant vapor and enters the absorber 53. The low-temperature refrigerant vapor entering the absorber 53 is sprayed and absorbed by the concentrated refrigerant solution in the absorber 53 and becomes a diluted refrigerant solution. The diluted refrigerant solution is sent to the generator 51 by the solution pump 58 after passing through the heat exchanger 52. The diluted refrigerant solution sent to the generator 51 is heated and concentrated by the saturated steam entering through the steam inlet 511 of the generator 51 to generate high-pressure refrigerant vapor. At the same time, the concentration of the diluted refrigerant solution increases to become a concentrated refrigerant solution. The concentrated refrigerant solution returns to the absorber 53 after passing through the heat exchanger 52, and the generated high-pressure refrigerant vapor enters the first condenser 55 to release heat and form a low-temperature refrigerant solution. The low-temperature refrigerant solution enters the first evaporator 54, and the above cycle is repeated during the operation of the system.

[0042] In the above cycle, the cold water inlet 534 of the absorber 53 is the cold water inlet 175 of the heat pump system 17, and the hot water outlet 554 of the first condenser 55 is the hot water outlet 176 of the heat pump system 17. As shown in Figure 1 Combined, the cold water enters the absorber 53 through the heating user return pipe 47, the sixth pipeline 36, and the cold water inlet 534 of the absorber 53. After being heated in the first stage by the absorber 53, it enters the first condenser 55 through the eighth heat pump system pipeline 68 and the water inlet 552 of the first condenser 55. After being heated in the second stage by the first condenser 55, it is output from the hot water outlet 554 of the first condenser 55. The output hot water can be sent for heating or to the ORC system 19 as the heat source for driving the expander 20 in the ORC system 19.

[0043] In the above cycle, the steam inlet 511 of the generator 51 is the saturated steam inlet 172 of the heat pump system 17, and the outlet of the first heat pump system pipeline 61 is the condensate outlet 172 of the heat pump system 17. Combining Figure 1 As shown, the low-temperature saturated steam of the condensing steam turbine 11 enters the generator 51 through the low-temperature saturated steam outlet 112, the fourth pipeline 34, and the steam inlet 511 of the generator 51. After indirectly exchanging heat and releasing heat with the refrigerant solution in the generator 51, it is output through the drain pump 56 and the first heat pump system pipeline 61, and the output condensate is output through the third pipeline 33.

[0044] Among them, the circulating water inlet 543 of the first evaporator 54 is the circulating water inlet 173 of the heat pump system 17, and the circulating water outlet 544 of the first evaporator 54 is the circulating water outlet 174 of the heat pump system 17. A part of the surplus hot water output from the second circulating pipeline 42 returns to the cooling tower 18, and the other part enters the circulating water inlet 543 of the first evaporator 54 to form a part of the circulating water. After releasing heat through the first evaporator 54, it is output from the circulating water outlet 544 of the first evaporator 54 and the fifth circulating pipeline 45. The circulating water output from the fifth circulating pipeline 45 converges with the cold water output from the cooling tower 18 and then enters the condenser 13 through the suction well 16 and the circulating water pump 15 to form a cycle.

[0045] Embodiment Three

[0046] Based on Embodiment Two, a water storage tank 510 is provided on the first heat pump system pipeline 61 between the condensate outlet 512 of the generator 51 and the drain pump 56. During actual use, when refrigerant needs to be replenished into the heat pump system 17, a refrigerant storage tank 520 can be provided on the ninth heat pump system pipeline 69 between the refrigerant solution outlet 546 of the first evaporator 54 and the first working medium pump 57. The purpose of replenishing refrigerant into the heat pump system 19 can be achieved by adding refrigerant to the refrigerant storage tank 520, as Figure 8 shown.

[0047] Embodiment Four

[0048] This embodiment elaborates on the ORC system 19 based on Embodiment One or Embodiment Two or Embodiment Three.

[0049] As Figure 9As shown, the specific structure of the ORC system 19 described in this embodiment includes: a second evaporator 71, a second condenser 72 and a liquid storage tank 73. A first ORC system pipeline 81 with a hot water pump 74 is connected to the hot water inlet 711 of the second evaporator 71, the inlet of the first ORC system pipeline 81 is the hot water inlet 192 of the ORC system 19, the cold water outlet 712 of the second evaporator 71 is the cold water outlet 191 of the ORC system 19, the working fluid steam outlet 713 of the second evaporator 17 is the working fluid steam outlet 193 of the ORC system 19, the working fluid solution inlet 714 of the second evaporator 71 is connected to the outlet 731 of the liquid storage tank 73 through the second ORC system pipeline 82 with a second working fluid pump 75, and the outlet 731 of the liquid storage tank 73 is connected to the outlet 732 of the liquid storage tank 73. The inlet 732 is connected to the working fluid outlet 721 of the second condenser 72 through the third ORC system pipeline 83. The working fluid inlet 722 of the second condenser 72 is the working fluid liquid inlet 194 of the ORC system 19. The second condenser 72 adopts an air cooling method: an air inlet 723 and an air outlet 724 are provided on the second condenser 72. A fourth ORC system pipeline 84 with a fan 76 is connected to the air inlet 723 of the second condenser 72. The outside air is continuously input into the second condenser 72 through the fan 76, and the working fluid solution entering the second condenser 72 is air-cooled.

[0050] The liquid working medium in the liquid storage tank 73 is pressurized by the second working medium pump 75 and enters the second evaporator 71. The liquid working medium absorbs heat at a constant pressure in the second evaporator 71 (this process includes preheating process, isothermal evaporation process and superheating process), and becomes superheated steam with a certain temperature and pressure, that is, high-temperature and high-pressure gaseous working medium. The high-temperature and high-pressure gaseous working medium enters the expander 20 to do work, and the exhaust gas generated enters the second condenser 72 to complete the isobaric condensation process (air cooling). At this point, the system completes a cycle. The expander 20 does work and converts heat into mechanical work output. The mechanical work is converted into electrical energy through the permanent magnet motor 21. The generated electrical energy can be fully incorporated into the power grid, or partially incorporated into the power grid and partially used for other purposes.

[0051] As shown in Table 1, Table 2 and Table 3 below, the relevant parameters of the condensing steam turbine 11, the condenser 13 and the cooling tower 18 are respectively given. Before the circulating water waste heat system is set, due to the presence of non-condensable gas in the condenser 13 and the high temperature in summer, the vacuum degree of the condenser 13 is reduced and the circulating water outlet temperature is increased. The average temperature in summer is 35°C, and the highest is 43.2°C. The cooling of the cooling tower 18 increases the evaporation of the circulating water, resulting in an increase in the amount of water replenishment, reaching 42,000 tons / day in summer, and the load limit situation increases.

[0052] Table 1 Condensing steam turbine related parameters

[0053] Name Relevant Parameters Model Unit N600-16.77 / 538 / 538 Unit Type Subcritical, Condensing Power Rated: 600MW Speed 3000 r / min Exhaust Pressure 4.9 kPa

[0054] Table 2 Condenser-related Parameter Table

[0055] Name Relevant Parameters Model Model N-38000-4 Type Double Shell, Double Back Pressure, Double Inlet and Double Outlet Cooling Area <![CDATA[38000m 2 > Cooling Water Quantity 69680 t / h Average Back Pressure 0.0049 MPa Cooling Water Temperature 20°C (maximum 33°C) Condensate Pump Flow <![CDATA[1721.3m 3 / h]]>

[0056] Table 3 Cooling Tower-related Parameter Table

[0057] Name Relevant Parameters Cooling Area <![CDATA[6500m 2 > Tower Height 132.5m Inlet Tower Water Temperature 39.91℃ Outlet Tower Water Temperature 29.89℃

[0058] Table 4 Related Performance Parameter Table of Heat Pump System

[0059]

[0060] Table 5 Related Parameter Table of Combined Cycle with R123 as Working Fluid

[0061]

[0062] Taking the relevant parameters in Table 4 and Table 5 as examples: The annual power generation of the previous year is calculated based on 7000 hours of operation in the south in a year. The power generation efficiency is the ratio of the power generation of the system to the power generation of the power plant. The mechanical efficiency of the expander is taken as 0.75.

[0063] Economic benefits: 53120 tons of standard coal are saved throughout the year. Calculated at 1000 yuan per ton of standard coal, a total of 53,120,000 yuan is saved. The evaporation of circulating water is reduced by 2 million tons, saving a total of 2 million yuan. Among them, the boiler efficiency is calculated at 55%.

[0064] It can be seen from the above calculation data that this combined cycle can effectively reduce the temperature of the circulating water at the inlet of Condenser 13, improve the vacuum degree of Condenser 13, save the consumption of water resources, and increase the additional power generation. While saving natural resources, the economic benefits are remarkable.

[0065] The above description is only the preferred embodiment of the present invention, and it is not intended to limit the present invention in any other form. Any modification or equivalent change made according to the technical essence of the present invention still belongs to the scope of protection required by the present invention.

Claims

1. A waste heat system for power plant circulating water, comprising: A condensing steam turbine with a generator, a condenser, a condensate pump, a circulating water pump, a suction well, a cooling tower and a heat pump system; characterized in that: the exhaust gas outlet of the condensing steam turbine is communicated with the steam inlet of the condenser through a first pipeline, a second pipeline with a condensate pump is connected at the condensate outlet of the condenser, and the second pipeline converges and is communicated with a third pipeline; the water outlet of the suction well is communicated with the cooling water inlet of the condenser through a first circulating pipeline with a circulating water pump, the cooling water outlet of the condenser is communicated with a second circulating pipeline, the outlet of the second circulating pipeline is communicated with the inlet of the cooling tower, and the outlet of the cooling tower is communicated with the inlet of the suction well through a third circulating pipeline; the low-pressure saturated steam outlet of the condensing steam turbine is communicated with the saturated steam inlet of the heat pump system through a fourth pipeline, and the condensate outlet of the heat pump system is connected to the third pipeline through a fifth pipeline; a fourth circulating pipeline is arranged on the second circulating pipeline, and the outlet of the fourth circulating pipeline is communicated with the circulating water inlet of the heat pump system, and the circulating water outlet of the heat pump system is connected to the third circulating pipeline through a fifth circulating pipeline; the power station circulating water waste heat system further includes: an ORC system, an expander with a permanent magnet motor; the cold water inlet of the heat pump system is communicated with the cold water outlet of the ORC system through a sixth pipeline, the water outlet of the heating user return water pipe is connected to the sixth pipeline, the hot water outlet of the heat pump system is communicated with the hot water inlet of the ORC system through a seventh pipeline, and the water inlet of the heating user supply water pipe is connected to the seventh pipeline; the working medium steam outlet of the ORC system is communicated with the gas inlet of the expander through an eighth pipeline, and the liquid outlet of the expander is communicated with the working medium liquid inlet of the ORC system through a ninth pipeline; at least one valve is installed respectively on the second pipeline, the third pipeline, the fourth pipeline, the fifth pipeline, the sixth pipeline, the seventh pipeline between the connection of the heating user supply water pipe to the outlet of the seventh pipeline, the heating user supply water pipe, the eighth pipeline, the ninth pipeline, the first circulating pipeline and the second circulating pipeline.

2. The waste heat system of the power station circulating water according to claim 1, characterized in that: The described heat pump system includes: a first condenser, a generator, a heat exchanger, an absorber, and a first evaporator; the steam inlet of the generator is the saturated steam inlet of the heat pump system, a first heat pump system pipeline with a condensate pump is connected at the condensate outlet of the generator, the outlet of the first heat pump system pipeline is the condensate outlet of the heat pump system, the refrigerant vapor outlet of the generator is communicated with the refrigerant vapor inlet of the first condenser through a second heat pump system pipeline, the concentrated refrigerant solution outlet of the generator is communicated with the concentrated refrigerant inlet of the heat exchanger through a third heat pump system pipeline, the concentrated refrigerant outlet of the heat exchanger is communicated with the spray pipe inlet of the absorber through a fourth heat pump system pipeline, the diluted refrigerant outlet of the heat exchanger is communicated with the diluted refrigerant solution inlet of the generator through a fifth heat pump system pipeline; the low-temperature refrigerant vapor inlet of the absorber is communicated with the low-temperature refrigerant vapor outlet of the first evaporator through a sixth heat pump system pipeline, the diluted refrigerant solution outlet of the absorber is communicated with the diluted refrigerant inlet of the heat exchanger through a seventh heat pump system pipeline with a solution pump, the cold water inlet of the absorber is the cold water inlet of the heat pump system, the hot water outlet of the absorber is communicated with the water inlet of the first condenser through an eighth heat pump system pipeline; the refrigerant solution outlet of the first evaporator is communicated with the spray pipe inlet of the first evaporator through a ninth heat pump system pipeline with a first working fluid pump, the circulating water inlet of the first evaporator is the circulating water inlet of the heat pump system, the circulating water outlet of the first evaporator is the circulating water outlet of the heat pump system; the refrigerant solution outlet of the first condenser is communicated with the refrigerant solution inlet on the first evaporator through a tenth heat pump system pipeline with a throttle valve, the hot water outlet of the first condenser is the hot water outlet of the heat pump system.

3. The waste heat system of the power station circulating water according to claim 2, characterized in that: A water storage tank is provided on the first heat pump system pipeline between the condensate outlet of the generator and the condensate pump.

4. A waste heat system for power plant circulating water according to claim 2 or 3, characterized in that: A refrigerant liquid storage tank is provided on the ninth heat pump system pipeline between the refrigerant solution outlet of the first evaporator and the first working fluid pump.

5. A waste heat system for power station circulating water according to claim 1 or 2, characterized in that: The refrigerant in the heat pump system is lithium bromide solution.

6. The waste heat system of the power station circulating water according to claim 1 or 2, characterized in that: The described ORC system includes: a second evaporator, a second condenser, and a liquid storage tank; a first ORC system pipeline with a hot water pump is connected at the hot water inlet of the second evaporator, the inlet of the first ORC system pipeline is the hot water inlet of the ORC system, the cold water outlet of the second evaporator is the cold water outlet of the ORC system, the working fluid vapor outlet of the second evaporator is the working fluid vapor outlet of the ORC system, the working fluid solution inlet of the second evaporator is communicated with the outlet of the liquid storage tank through a second ORC system pipeline with a second working fluid pump, the inlet of the liquid storage tank is communicated with the working fluid outlet of the second condenser through a third ORC system pipeline, the working fluid inlet of the second condenser is the working fluid liquid inlet of the ORC system, an air inlet and an air outlet are further provided on the second condenser, and a fourth ORC system pipeline with a fan is connected at the air inlet of the second condenser.

7. A waste heat system for power station circulating water according to claim 1, characterized in that: The working fluid in the ORC system is R123 solution.

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