Backpressure reducing system of indirect air cooling unit and power generation system

Abstract

The invention relates to the technical field of power plant energy conservation, in particular to an indirect air cooling unit back pressure reducing system and a power generation system. Circulating water is arranged in the first cooling module and the second cooling module and exchanges heat with high-temperature steam of the heat removal module through the condenser, and the high-temperature circulating water after heat exchange flows into the first cooling module and the second cooling module to be cooled and then is put into the condenser again to exchange heat. And the second cooling module exchanges heat with part of the circulating water through the refrigerant, exchanges heat with the condensed water of the heat removal module again after heat exchange, and exchanges heat with the circulating water again. The heat exchanger has the beneficial effects that circulating water enters the evaporator through the shunting part to exchange heat with a refrigerant, so that the outlet water temperature of the circulating water is reduced. Meanwhile, refrigerant in the condenser is used for releasing heat to heat condensed water at an outlet of the condenser, the supercooling degree of the condensed water is reduced, and the economical efficiency of the whole thermodynamic system is improved.

Description

Technical Field

[0001] The invention relates to the technical field of power plant energy saving, in particular to a back pressure reduction system of an indirect air cooling unit and a power generation system. Background Art

[0002] Indirect air-cooled units circulate water during the high temperature period in summer, and the water temperature out of the tower is high, which affects the operating performance of the condenser, which in turn causes the unit's operating vacuum to be low, restricting the unit's load-carrying capacity. In short, the cold end system consisting of the air-cooling tower, surface condenser and auxiliary systems has poor operating performance, causing the unit's operating back pressure to be high, and the unit's load-carrying capacity is limited during the high temperature period in summer. The high temperature period in summer coincides with the period when the grid load demand is high, but the operating performance of the cold end system is low, affecting the unit's load-carrying capacity. The contradiction between the unit's power generation and the grid demand becomes increasingly obvious, the unit's operating coal consumption rate increases, the unit's operating economy decreases, and the operating cost increases. Summary of the invention

[0003] In view of the above existing technical problems, the present invention is proposed.

[0004] To solve the above technical problems, the present invention provides the following technical solutions: a back pressure reduction system for an indirect air-cooling unit, comprising a heat rejection module, a first cooling module, and a second cooling module; there is circulating water in the first cooling module and the second cooling module, and the circulating water flows through the condenser to exchange heat with the high-temperature steam of the heat rejection module, and the high-temperature circulating water after the heat exchange flows into the first cooling module and the second cooling module to cool down, and then is re-entered into the condenser for heat exchange; after the second cooling module exchanges heat with part of the circulating water through the refrigerant, the refrigerant after heat exchange is again exchanged with the condensed water of the heat rejection module, and then exchanges heat with the circulating water again.

[0005] As a preferred solution of the back pressure reduction system of the indirect air-cooling unit of the present invention, the heat removal module includes a steam turbine, and the steam turbine discharges high-temperature steam.

[0006] As a preferred solution of the back pressure reduction system of the indirect air cooling unit of the present invention, wherein: the first cooling module includes an indirect air cooling tower, and the indirect air cooling tower is used to cool condensed water.

[0007] As a preferred solution of the back pressure reduction system of the indirect air cooling unit of the present invention, the second cooling module includes an evaporator, a compressor connected to the evaporator, and a condenser connected to the compressor.

[0008] As a preferred solution of the back pressure reduction system of the indirect air-cooling unit of the present invention, the turbine exhaust pipeline is connected to the condenser air inlet pipeline, and the high-temperature circulating water enters the indirect air-cooling tower for cooling and then flows back into the condenser for heat exchange with the high-temperature steam exhausted from the turbine.

[0009] As a preferred solution of the back pressure reduction system of the indirect air-cooling unit of the present invention, the high-temperature circulating water circulating in the condenser is also diverted to the evaporator. The evaporator contains refrigerant. The circulating water after heat exchange in the condenser exchanges heat with the refrigerant and then combines with the circulating water after cooling in the indirect air-cooling tower and flows into the condenser for heat exchange.

[0010] As a preferred solution of the back pressure reduction system of the indirect air-cooling unit of the present invention, the refrigerant enters the condenser after being pressurized by the compressor, and the condensed water of the high-temperature steam discharged from the turbine enters the condenser after heat exchange with the refrigerant and enters the condensate system after heat exchange with the refrigerant.

[0011] As a preferred solution of the back pressure reduction system of the indirect air cooling unit of the present invention, the refrigerant exchanges heat with the condensed water and then re-enters the evaporator to exchange heat with the high-temperature circulating water.

[0012] As a preferred solution of the back pressure reduction system of the indirect air cooling unit of the present invention, a booster pump is arranged between the evaporator water inlet pipeline and the high-temperature circulating water pipeline, and a throttle valve is arranged between the condenser and the evaporator.

[0013] The present invention also provides the following technical solution: a power generation system, including an indirect air-cooling unit back pressure reduction system.

[0014] The beneficial effects of the indirect air-cooling unit back pressure reduction system of the present invention are: by diverting part of the circulating water into the evaporator for heat exchange with the refrigerant, the heat load entering the intercooling tower is reduced, thereby reducing the circulating water outlet temperature, thereby achieving the purpose of reducing the unit back pressure and increasing the turbine output. At the same time, the refrigerant in the condenser releases heat to heat the condensate at the condenser outlet, reduce the supercooling of the condensate, and improve the economy of the entire thermal system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0016] Figure 1 It is an overall schematic diagram of the back pressure reduction system of the indirect air cooling unit in the present invention.

[0017] In the figure: 100, heat rejection module; 101, steam turbine; 102, condensate pump; 103, generator; 200, first cooling module; 201, indirect air cooling tower; 300, second cooling module; 301, evaporator; 302, compressor; 303, condenser; 301a, booster pump; 303a, throttle valve; 400, condenser; 400a, circulating water pump. DETAILED DESCRIPTION

[0018] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0019] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0020] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0021] Example 1 Reference Figure 1 , which is the first embodiment of the present invention, and provides a back pressure reduction system for an indirect air-cooling unit, including a heat rejection module 100, a first cooling module 200, and a second cooling module 300; there is circulating water in the first cooling module 200 and the second cooling module 300, and the circulating water flows through the condenser 400 to exchange heat with the high-temperature steam of the heat rejection module 100, and the high-temperature circulating water after heat exchange flows into the first cooling module 200 and the second cooling module 300 to cool down, and then is re-entered into the condenser 400 for heat exchange; after the second cooling module 300 exchanges heat with part of the circulating water through the refrigerant, the refrigerant after heat exchange is heat-exchanged with the condensed water of the heat rejection module 100 again, and then exchanges heat with the circulating water again.

[0022] Preferably, the heat removal module 100 generates high-temperature steam during operation, and the high-temperature steam loses heat to form condensed water after heat exchange with the circulating water in the first cooling module 200 and the second cooling module 300 in the condenser 400.

[0023] Furthermore, the circulating water after heat exchange receives heat from the heat rejection module 100, becomes high-temperature circulating water, and is then diverted to flow into the first cooling module 200 and the second cooling module 300 respectively. The high-temperature circulating water undergoes heat exchange in different ways in their respective modules, and then becomes cooled circulating water again to participate in the heat exchange work of the heat rejection module 100.

[0024] The high-temperature circulating water flowing through the first cooling module 200 exchanges heat through contact with cold air; the high-temperature circulating water flowing through the second cooling module 300 absorbs heat from the high-temperature circulating water through the refrigerant.

[0025] After being cooled by the first cooling module 200 and the second cooling module 300 , the cooled circulating water is collected through pipelines and re-enters the heat exchange between the condenser 400 and the heat exhaust module 100 .

[0026] In addition, after the high-temperature steam discharged from the heat removal module 100 is heat exchanged with the circulating water in the condenser 400, the high-temperature steam releases heat and condenses into condensed water. At this time, the low-temperature condensed water cannot directly participate in the condensed water system. For example, if it participates in the combustion of the boiler to release steam to supply the heat removal module 100 for power generation of the generator 103, the above-mentioned refrigerant stores a large amount of heat inside at this time. After the low-temperature condensed water is heat exchanged with the refrigerant carrying a large amount of heat, the temperature of the low-temperature condensed water increases and it can return to the condensed water system. Moreover, the heat of the refrigerant at this time is consumed and can return to the refrigeration process of the high-temperature circulating water.

[0027] In summary, by diverting the high-temperature circulating water, part of the circulating water enters the second cooling module 300 to exchange heat with the refrigerant, reducing the heat load entering the first cooling module 200 and thus reducing the circulating water outlet temperature, thereby achieving the purpose of reducing the back pressure of the unit and increasing the output of the steam turbine 101. At the same time, the refrigerant is used to release heat to heat the condensed water discharged from the heat exhaust module 100 through the condenser 400, reducing the supercooling of the condensed water and improving the economy of the entire thermal system.

[0028] Example 2 Reference Figure 1 , which is the second embodiment of the present invention, and this embodiment further provides a back pressure reduction system for an indirect air cooling unit.

[0029] Preferably, all the high-temperature circulating water after heat exchange is passed into the second cooling module 300 for cooling.

[0030] In winter, the ambient temperature drops, especially at night or in cold areas, the temperature may drop below freezing, which may cause the circulating water in the first cooling module 200 to be at risk of freezing. At this time, the circulating water flow rate is smaller in winter and can all enter the second cooling module 300 for cooling, which can also solve the anti-freezing problem of the first cooling module 200.

[0031] Example 3 Reference Figure 1 , which is the third embodiment of the present invention, and this embodiment further provides a back pressure reduction system for an indirect air-cooling unit, including: a heat removal module 100 includes a steam turbine 101, and the steam turbine 101 discharges high-temperature steam.

[0032] The first cooling module 200 includes an indirect air cooling tower 201, and the indirect air cooling tower 201 is used to cool condensed water.

[0033] Preferably, the outlet water pipeline of the indirect air-cooling tower 201 is connected to the condenser 400, and is used to transport the cooled circulating water to the condenser 400. A circulating water pump 400a is provided between the high-temperature circulating water pipeline of the condenser 400 (the high-temperature circulating water pipeline refers to the pipeline for transporting circulating water into the indirect air-cooling tower 201 that flows out after heat exchange with the high-temperature steam discharged from the condenser 400 and the turbine 101) and the water inlet of the indirect air-cooling tower 201, and is used to stably transport the high-temperature circulating water to the indirect air-cooling tower 201 for heat exchange and cooling.

[0034] Preferably, the steam turbine 101 provides power to the generator 103, so that the generator 103 generates electricity.

[0035] The second cooling module 300 includes an evaporator 301 , a compressor 302 connected to the evaporator 301 , and a condenser 303 connected to the compressor 302 .

[0036] Preferably, the water inlet pipeline of the evaporator 301 is connected to the high-temperature circulating water pipeline of the condenser 400, diverting the high-temperature circulating water that originally only enters the indirect air-cooling tower 201, reducing the heat load of the indirect air-cooling tower 201, and thus reducing the outlet water temperature of the indirect air-cooling tower 201.

[0037] The exhaust pipeline of the steam turbine 101 is connected to the air inlet pipeline of the condenser 400 . The high-temperature circulating water enters the indirect air cooling tower 201 for cooling and then flows back into the condenser 400 to exchange heat with the high-temperature steam exhausted from the steam turbine 101 .

[0038] Preferably, the high-temperature steam exhausted from the steam turbine 101 is condensed water through heat exchange in the condenser 400 , and the condensed water pipeline is directly connected to the water inlet pipeline of the condenser 303 .

[0039] The high-temperature circulating water in the condenser 400 is also diverted to the evaporator 301. The evaporator 301 contains refrigerant. The circulating water after heat exchange in the condenser 400 exchanges heat with the refrigerant, and then combines with the circulating water after cooling in the indirect air-cooling tower 201 and flows into the condenser 400 for heat exchange.

[0040] Preferably, the refrigerant can be R22 or R245fa.

[0041] The refrigerant is pressurized by the compressor 302 and enters the condenser 303. The condensed water of the high-temperature steam discharged from the turbine 101 enters the condenser 303 after heat exchange with the refrigerant through the condenser 400 and enters the condensed water system.

[0042] After the refrigerant exchanges heat with the condensed water, it re-enters the evaporator 301 to exchange heat with the high-temperature circulating water.

[0043] A booster pump 301 a is provided between the water inlet pipeline of the evaporator 301 and the high-temperature circulating water pipeline, and a throttle valve 303 a is provided between the condenser 303 and the evaporator 301 .

[0044] In summary, the exhaust steam of the steam turbine 101 enters the condenser 400 and is cooled by the circulating water. A part of the circulating water from the condenser 400 enters the evaporator 301 through the booster pump 301a and is cooled by the refrigerant, and the other part enters the indirect air cooling tower 201 for cooling. The two streams of circulating water after cooling merge and enter the condenser 400 again. The exhaust steam of the steam turbine 101 is condensed into condensed water through the condenser 400. The condensed water enters the condenser 303 through the condensate pump 102 to exchange heat with the refrigerant, and the heated condensed water returns to the condensate system again. The refrigerant is pressurized by the compressor 302 and enters the condenser 303 to exchange heat with the condensed water. The condensed refrigerant is throttled by the throttle valve 303a in turn and enters the cold side of the evaporator 301, the purpose of which is to cool the circulating water. Finally, the refrigerant returns to the compressor 302. The waste heat of the circulating water is utilized, the vacuum degree of the condenser is improved, the supercooling degree of the condensed water is reduced, and the economy of the entire thermal system is improved. The heat of circulating water is recovered by utilizing the principle of heat absorption by refrigerant evaporation, thereby reducing the temperature of circulating water entering the condenser 400, increasing the vacuum degree of the condenser 400, reducing the back pressure of the steam turbine 101, and increasing the output of the steam turbine 101. The condensed water is heated by utilizing the principle of heat release by refrigerant condensation, thereby reducing the supercooling degree of the condensed water and the oxygen content in the condensed water, improving the thermal economic performance of the unit, improving the energy efficiency of the system, and realizing the cascade utilization of energy.

[0045] Example 4 Reference Figure 1 , which is the fourth embodiment of the present invention, provides a power generation system, including an indirect air-cooling unit back pressure reduction system.

[0046] In the power generation system, an indirect air-cooled unit back pressure reduction system is used. By diverting part of the circulating water into the evaporator 301 for heat exchange with the refrigerant, the heat load is reduced and the circulating water outlet temperature is reduced, thereby increasing the vacuum degree of the condenser 400 and increasing the output of the turbine 101. At the same time, the condensate is heated by utilizing the heat release principle of the refrigerant condensation to reduce the degree of subcooling and improve the economy of the thermal system, thus achieving the goal of reducing the back pressure of the unit and improving the power generation efficiency and economy.

[0047] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A back pressure reduction system for an indirect air cooling unit, characterized in that: include, A heat removal module (100), a first cooling module (200), and a second cooling module (300); There is circulating water in the first cooling module (200) and the second cooling module (300), and the circulating water flows through the condenser (400) to exchange heat with the high-temperature steam of the heat exhaust module (100), and the high-temperature circulating water after the heat exchange flows into the first cooling module (200) and the second cooling module (300) to cool down, and then is re-entered into the condenser (400) for heat exchange; After the second cooling module (300) exchanges heat with part of the circulating water through the refrigerant, the refrigerant after the heat exchange exchanges heat with the condensed water of the heat exhaust module (100) again, and then exchanges heat with the circulating water again.

2. The back pressure reduction system for an indirect air cooling unit according to claim 1, characterized in that: The heat exhaust module (100) comprises a steam turbine (101), and the steam turbine (101) exhausts high-temperature steam.

3. The back pressure reduction system for an indirect air cooling unit according to claim 2, characterized in that: The first cooling module (200) comprises an indirect air cooling tower (201), and the indirect air cooling tower (201) is used to cool condensed water.

4. The back pressure reduction system for an indirect air cooling unit according to claim 3, characterized in that: The second cooling module (300) comprises an evaporator (301), a compressor (302) connected to the evaporator (301), and a condenser (303) connected to the compressor (302).

5. The back pressure reduction system for an indirect air cooling unit according to claim 4, characterized in that: The exhaust pipeline of the steam turbine (101) is connected to the air inlet pipeline of the condenser (400), and the high-temperature circulating water enters the indirect air cooling tower (201) for cooling and then flows back into the condenser (400) for heat exchange with the high-temperature steam exhausted from the steam turbine (101).

6. The back pressure reduction system for an indirect air cooling unit according to claim 5, characterized in that: The high-temperature circulating water in the condenser (400) is also diverted to the evaporator (301). The evaporator (301) contains refrigerant. The circulating water after heat exchange in the condenser (400) exchanges heat with the refrigerant and then combines with the circulating water after cooling in the indirect air cooling tower (201) to flow into the condenser (400) for heat exchange.

7. The back pressure reduction system for an indirect air cooling unit according to claim 6, characterized in that: The refrigerant is pressurized by the compressor (302) and enters the condenser (303). The high-temperature steam discharged from the turbine (101) is condensed water after heat exchange in the condenser (400) and enters the condenser (303) to exchange heat with the refrigerant and then enter the condensate system.

8. The back pressure reduction system for an indirect air cooling unit according to claim 7, characterized in that: After the refrigerant exchanges heat with the condensed water, it re-enters the evaporator (301) to exchange heat with the high-temperature circulating water.

9. The back pressure reduction system for an indirect air cooling unit according to claim 8, characterized in that: A booster pump (301a) is provided between the water inlet pipeline of the evaporator (301) and the high-temperature circulating water pipeline, and a throttle valve (303a) is provided between the condenser (303) and the evaporator (301).

10. A power generation system, characterized in that: It comprises the back pressure reduction system of the indirect air cooling unit as described in any one of claims 1 to 9.

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