A system and method for utilizing exhaust steam of a gas-steam combined cycle unit

Abstract

The application discloses a kind of steam utilization system and operating method of gas steam combined cycle unit, including heat pump, condenser, heat user, regenerative heater, air heat exchanger, circulating water pump, heat network water pump, condensate pump and cooling water pump;Condenser is connected with heat pump by circulating water pipeline, and circulating water pump is connected on circulating water pipeline;Heat user is connected with heat pump by heat network water pipeline, and heat network water pump is connected on heat network water pipeline;Regenerative heater is connected with heat pump by condensate pipeline, and condensate pump is connected on condensate pipeline;Air heat exchanger is connected with heat pump by cooling water pipeline, and cooling water pump is connected on cooling water pipeline.Extract the heat of steam turbine exhaust steam by heat pump, heating in winter, provide heat source for heat user;Cooling in summer, reduce condenser inlet circulating water temperature and air temperature of compressor inlet, create favorable operating conditions for equipment.

Description

Technical Field

[0001] This invention belongs to the field of energy utilization technology for gas-fired steam combined cycle units, specifically relating to a waste steam utilization system and operation method for gas-fired steam combined cycle units. Background Technology

[0002] New energy power generation, especially gas-steam combined generator units, has been vigorously developed due to its many advantages such as environmental protection, low carbon emissions, and rapid start-up and shutdown. It plays a positive role in meeting the growing demand for electricity load, improving the power grid structure, and enhancing the reliability of power supply, thus becoming an important support for the new power system.

[0003] For gas turbines, the compressor consumes approximately 60% of the turbine's power output. During actual unit operation, the gas turbine's output power is affected by multiple operating parameters, with ambient temperature having a significant impact. For example, for a 128MW gas turbine, for every 1°C increase in ambient temperature during summer, the turbine's power generation will decrease by approximately 0.65%.

[0004] For steam turbines, high-temperature, high-pressure steam performs work within the turbine. The exhaust steam, having done work, needs to be condensed into water in the condenser for recycling. This process releases a significant amount of heat, resulting in heat loss, exceeding 50%. In summer, due to ambient temperature, the unit operates in a low-vacuum mode, reducing its economic efficiency. For example, in a combined cycle unit with a 128MW gas turbine and a 65MW steam turbine, for every 1°C increase in the condenser circulating water inlet temperature due to ambient temperature, the unit's vacuum decreases by approximately 0.5 kPa, and the steam turbine's power generation capacity decreases by approximately 0.67%.

[0005] Due to limitations in steam turbine manufacturing processes, heat loss of exhaust steam in the condenser is unavoidable. Furthermore, the uncontrollable natural environment, particularly high temperatures, increases compressor power consumption, reduces gas turbine output power, and simultaneously lowers condenser vacuum, decreasing the steam turbine's work capacity. These factors, combined with the influence of manufacturing processes and ambient temperature, increase the energy consumption for power generation in gas-fired steam combined cycle units. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned shortcomings in the prior art and to provide a reasonable and reliable waste steam utilization system and operation method for gas-steam combined cycle units, which can reduce power generation energy consumption.

[0007] The technical solution adopted by this invention to solve the above problems is: a waste steam utilization system for a gas-fired steam combined cycle unit, characterized in that it includes a lithium bromide absorption heat pump (hereinafter referred to as a heat pump), a condenser, a heat user, a regenerative heater, an air heat exchanger, a circulating water pump, a heating network water pump, a condensate pump, and a cooling water pump; the condenser is connected to the heat pump through a circulating water pipeline, and the circulating water pump is connected to the circulating water pipeline; the heat user is connected to the heat pump through a heating network water pipeline, and the heating network water pump is connected to the heating network water pipeline; the regenerative heater is connected to the heat pump through a condensate pipeline, and the condensate pump is connected to the condensate pipeline; the air heat exchanger is connected to the heat pump through a cooling water pipeline, and the cooling water pump is connected to the cooling water pipeline; The circulating water pipeline includes a main circulating water pipeline and circulating water sub-pipelines. Valves 2 and 4 are installed on the main circulating water pipeline, and valves 1 and 3 are installed on the circulating water sub-pipelines. The heating network water pipeline includes a main heating network water pipeline and heating network water sub-pipelines. Valves 6 and 8 are installed on the main heating network water pipeline, and valves 5 and 7 are installed on the heating network water sub-pipelines. The condensate pipeline includes a main condensate water pipeline and condensate water sub-pipelines. Valves 9, 10, and 11 are installed on the main condensate water pipeline. The cooling water pipeline includes a main cooling water pipeline and cooling water sub-pipelines. Valves 13 and 14 are installed on the main cooling water pipeline, and valve 12 is installed on the cooling water sub-pipelines. Valve 15 is installed on the steam inlet pipe of the heat pump.

[0008] Furthermore, the circulating water pump is installed on the main circulating water pipeline, the heating network water pump is installed on the main heating network water pipeline, the condensate pump is installed on the condensate water pipeline, and the cooling water pump is installed on the main cooling water pipeline.

[0009] Furthermore, the driving steam for the heat pump comes from steam extracted from the steam turbine; the condenser cools the exhaust steam from the steam turbine using circulating water as the cooling medium, and the circulating water pump can send the circulating water into the condenser; the high-temperature water for the heat users comes from the heat pump, and the heating network water pump can send the heating network water to the heat users; the regenerative heater uses steam extracted from the steam turbine to heat the condensate, and the condensate pump can send the water condensed from the exhaust steam into the heat pump; the air heat exchanger uses cooling water to reduce the temperature of the air entering the compressor, and the cooling water pump can send the cooling water into the air heat exchanger.

[0010] Furthermore, the heat from the exhaust steam of the steam turbine is released to the circulating water in the condenser. The heated circulating water enters the heat pump through the circulating water pipeline, where it releases heat. The cooled circulating water then re-enters the condenser. The return water from the heat users enters the heat pump through the heating network water pipeline, where it absorbs heat and is then supplied to the heat users. The water condensed from the exhaust steam of the steam turbine in the condenser enters the heat pump through the condensate pipeline, where it absorbs heat and is then fed into the regenerative heater. The inlet air of the air heat exchanger exchanges heat with the cooling water in the air heat exchanger. The heated cooling water enters the heat pump through the cooling water pipeline, where it absorbs heat and is then fed back into the air heat exchanger. The driving steam source of the heat pump releases heat within the heat pump, and the condensed water returns to the regenerative heater.

[0011] The operation method is as follows: During winter operation, heat is extracted from the exhaust steam using a heat pump and released to the heating network water for use by heat users; the exhaust steam of the steam turbine is fully utilized with no heat loss; according to the first law of thermodynamics, the steam turbine efficiency can theoretically reach 100%.

[0012] During summer operation, the heat pump extracts heat from the exhaust steam and releases it to the water condensed from the exhaust steam; this reduces the steam consumption of the regenerator and increases the steam's work capacity; at the same time, the temperature of the circulating water at the condenser inlet is reduced, which improves the unit's vacuum and increases the unit's output; the heat pump is used to cool the cooling water, and heat is extracted from the air through the cooling water medium, which reduces the temperature of the air entering the compressor, reduces the compressor's power consumption, and increases the gas turbine's output power.

[0013] When the heat pump stops running, the system can revert to its original operating mode.

[0014] Winter operation procedure: ① Open valves 1, 2, and 4, close valve 3, start the circulating water pump to introduce circulating water into the system, and close valve 1 after the circulating water pipeline is full of water; ② Open valves 5, 6, and 8, close valve 7, start the heating network water pump to introduce heating network water into the system, and close valve 5 after the heating network water pipeline is full of water; ③ Open valve 9, close valves 10 and 11, start the condensate pump, and prevent condensate from entering the heat pump; ④ Close valve 12, stop the cooling water pump, and prevent cooling water from entering the heat pump; ⑤ Open valve 15, and the heat pump will start operation.

[0015] Summer Operation Procedure: ① Open valves 1, 2, and 4, close valve 3, start the circulating water pump to introduce circulating water into the system, and close valve 1 after the circulating water pipeline is full of water; ② Close valves 5 and 7 to stop the heating network water pump; ③ Close valve 9, open valves 10 and 11 to start the condensate pump, and the condensate will enter the heat pump; ④ Open valves 12, 13, and 14 to start the cooling water pump and introduce cooling water into the system, and close valve 12 after the cooling water pipeline is full of water; ⑤ Open valve 15 to put the heat pump into operation.

[0016] Heat pump shutdown procedure: ① Close valve 15 to shut down the heat pump; ② Open valves 1 and 3, close valves 2 and 4, start the circulating water pump, and enter the circulating water system operation mode; ③ Open valves 5 and 7, close valves 6 and 8, start the heating network water pump, and enter the heating network water system operation mode; ④ Open valve 9, close valves 10 and 11, start the condensate pump, and enter the condensate system operation mode; ⑤ Close valve 12 to shut down the cooling water pump.

[0017] Compared with existing technologies, this invention has the following advantages and effects: the system is simple, reliable, and low in manufacturing cost. By extracting heat from the exhaust steam of the steam turbine using a heat pump, it provides heating for users in winter and cooling in summer, reducing the temperature of the condenser inlet circulating water and the compressor inlet air, creating favorable operating conditions for the equipment. Applying this invention solves the problem of heat loss from the exhaust steam of the steam turbine caused by the production process, as well as the problems of decreased steam turbine work capacity and increased compressor power consumption due to ambient temperature, thus reducing energy consumption and possessing high practical value. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the system of the present invention.

[0019] In the diagram: 1. Heat pump; 2. Condenser; 3. Heat user; 4. Regenerative heater; 5. Air heat exchanger; 6. Circulating water pump; 7. Heat network water pump; 8. Condensate pump; 9. Cooling water pump; 10. Valve 1; 11. Valve 2; 12. Valve 3; 13. Valve 4; 14. Valve 5; 15. Valve 6; 15. Valve 7; 16. Valve 8; 17. Valve 9; 18. Valve 10; 19. Valve 11; 20. Valve 12; 21. Valve 13; 22. Valve 14; 23. Valve 15; 24. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are explanations of the present invention, but the present invention is not limited to the following embodiments.

[0021] See Figure 1A waste steam utilization system for a gas-fired steam combined cycle unit includes a heat pump 1, a condenser 2, a heat user 3, a regenerative heater 4, an air heat exchanger 5, a circulating water pump 6, a heating network water pump 7, a condensate pump 8, and a cooling water pump 9. The condenser 2 is connected to the heat pump 1 via a circulating water pipeline, and the circulating water pump 6 is connected to the circulating water pipeline. The heat user 3 is connected to the heat pump 1 via a heating network water pipeline, and the heating network water pump 7 is connected to the heating network water pipeline. The regenerative heater 4 is connected to the heat pump 1 via a condensate pipeline, and the condensate pump 8 is connected to the condensate pipeline. The air heat exchanger 5 is connected to the heat pump 1 via a cooling water pipeline, and the cooling water pump 9 is connected to the cooling water pipeline.

[0022] Specifically, the circulating water pipeline includes a main circulating water pipeline and circulating water sub-pipelines. Valves 2.11 and 4.13 are installed on the main circulating water pipeline, and valves 1.10 and 3.12 are installed on the circulating water sub-pipelines. The heating network water pipeline includes a main heating network water pipeline and heating network sub-pipelines. Valves 6.15 and 8.17 are installed on the main heating network water pipeline, and valves 5.14 and 7.16 are installed on the heating network sub-pipelines. The condensate pipeline includes a main condensate water pipeline and condensate sub-pipelines. Valves 9.18, 10.19, and 11.20 are installed on the main condensate water pipeline. The cooling water pipeline includes a main cooling water pipeline and cooling water sub-pipelines. Valves 13.22 and 14.23 are installed on the main cooling water pipeline, and valve 12.21 is installed on the cooling water sub-pipelines. Valve 15.24 is installed on the steam inlet pipe of heat pump 1. Circulating water pump 6 is installed on the main circulating water line, heating network water pump 7 is installed on the main heating network water line, condensate pump 8 is installed on the condensate water line, and cooling water pump 9 is installed on the main cooling water line.

[0023] Specifically, the driving steam for heat pump 1 comes from steam extracted from the steam turbine; condenser 2 cools the exhaust steam from the steam turbine using circulating water as the cooling medium, and circulating water pump 6 can send the circulating water into condenser 2; the high-temperature water for heat user 3 comes from heat pump 1, and heating network water pump 7 can send heating network water into heat user 3; regenerative heater 4 uses steam extracted from the steam turbine to heat condensate, and condensate pump 8 can send the water condensed from the exhaust steam into heat pump 1; air heat exchanger 5 uses cooling water to reduce the temperature of the air entering the compressor, and cooling water pump 9 can send cooling water into air heat exchanger 5.

[0024] Specifically, the heat from the exhaust steam of the steam turbine is released to the circulating water in condenser 2. The heated circulating water enters heat pump 1 through the circulating water pipeline, where it releases heat. The cooled circulating water then re-enters condenser 2. The return water from heat user 3 enters heat pump 1 through the heating network water pipeline, where it absorbs heat. The heated hot water is then supplied to heat user 3. The water condensed from the exhaust steam of the steam turbine in condenser 2 enters heat pump 1 through the condensate pipeline, where it absorbs heat. The heated condensate then enters regenerative heater 4. The inlet air of air heat exchanger 5 exchanges heat with cooling water in air heat exchanger 5. The heated cooling water enters heat pump 1 through the cooling water pipeline, where it absorbs heat. The cooled water then re-enters air heat exchanger 5. The driving steam source of heat pump 1 releases heat in heat pump 1, and the condensed water returns to regenerative heater 4.

[0025] The operation method is as follows: During winter operation: ① Open valve 10, valve 21, and valve 43, close valve 312, and start circulating water pump 6 to introduce circulating water into the system. After the circulating water pipeline is full of water, close valve 10; ② Open valve 514, valve 615, and valve 817, close valve 716, and start heating network water pump 7 to introduce heating network water into the system. After the heating network water pipeline is full of water, close valve 514; ③ Open valve 918, close valve 1019 and valve 1120, and start condensate pump 8. Condensate will not enter heat pump 1; ④ Close valve 1221 and stop cooling water pump 9. Cooling water will not enter heat pump 1; ⑤ Open valve 1524 to start heat pump 1.

[0026] During summer operation: ① Open valve 10, valve 21, and valve 43, close valve 312, start circulating water pump 6 to introduce circulating water into the system, and close valve 10 after the circulating water pipeline is full of water; ② Close valve 514 and valve 716, and stop heating network water pump 7; ③ Close valve 918, open valve 1019 and valve 1120, start condensate pump 8, and condensate enters heat pump 1; ④ Open valve 1221, valve 1322, and valve 1423, start cooling water pump 9, and introduce cooling water into the system, and close valve 1221 after the cooling water pipeline is full of water; ⑤ Open valve 1524, and heat pump 1 is put into operation.

[0027] When heat pump 1 is shut down: ① Close valve 15 24 to shut down heat pump 1; ② Open valve 1 10 and valve 3 12, close valve 2 11 and valve 4 13, and start circulating water pump 6 to enter the circulating water source system operation mode; ③ Open valve 5 14 and valve 7 16, close valve 6 15 and valve 8 17, and start heating network water pump 7 to enter the heating network source system operation mode; ④ Open valve 9 18, close valve 10 19 and valve 11 20, and start condensate pump 8 to enter the condensate source system operation mode; ⑤ Close valve 12 21 to shut down cooling water pump 9.

[0028] Any content not described in detail in this specification is prior art known to those skilled in the art.

[0029] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the scope of protection of the present invention. Any modifications and refinements made by those skilled in the art without departing from the concept and scope of the present invention shall fall within the scope of protection of the present invention.

Claims

1. An operation method for a waste steam utilization system of a gas-fired combined cycle unit, wherein the waste steam utilization system of the gas-fired combined cycle unit includes a heat pump (1), a condenser (2), a heat user (3), a regenerative heater (4), an air heat exchanger (5), a circulating water pump (6), a heating network water pump (7), a condensate pump (8), and a cooling water pump (9); the condenser (2) is connected to the heat pump (1) through a circulating water pipeline, and the circulating water pump (6) is connected to the circulating water pipeline; the heat user (3) is connected to the heat user through a heating network water pipeline. The circuit is connected to the heat pump (1), and the heating network water pump (7) is connected to the heating network water pipeline; the regenerating heater (4) is connected to the heat pump (1) through the condensate pipeline, and the condensate pump (8) is connected to the condensate pipeline; the air heat exchanger (5) is connected to the heat pump (1) through the cooling water pipeline, and the cooling water pump (9) is connected to the cooling water pipeline; the circulating water pipeline includes a main circulating water pipeline and a secondary circulating water pipeline, and valves two (11) and four (13) are installed on the main circulating water pipeline, and the secondary circulating water pipeline... Valves 1 (10) and 3 (12) are installed on the pipelines respectively; the heating network water pipeline includes the main heating network water pipeline and the heating network water branch pipelines, valves 6 (15) and 8 (17) are installed on the main heating network water pipeline, and valves 5 (14) and 7 (16) are installed on the water branch pipelines respectively; the condensate pipeline includes the main condensate pipeline and the condensate water branch pipelines, and valves 9 (18), 10 (19) and 11 (20) are installed on the main condensate pipeline; the cooling water pipeline includes the cooling... The cooling water main pipeline and the cooling water pipeline are equipped with valves thirteen (22) and fourteen (23) on the cooling water main pipeline and valve twelfth (21) on the cooling water pipeline; valve fifteen (24) is installed on the steam inlet pipeline of the heat pump (1); the circulating water pump (6) is installed on the circulating water main pipeline, the heating network water pump (7) is installed on the heating network water main pipeline, the condensate pump (8) is installed on the condensate pipeline, and the cooling water pump (9) is installed on the cooling water main pipeline. The features are: During winter operation: ① Open valve 1 (10), valve 2 (11), and valve 4 (13), close valve 3 (12), start the circulating water pump (6) to introduce circulating water into the system, and close valve 1 (10) after the circulating water pipeline is full of water; ② Open valve 5 (14), valve 6 (15), and valve 8 (17), close valve 7 (16), start the heating network water pump (7) to introduce heating network water into the system, and close valve 5 (14) after the heating network water pipeline is full of water; ③ Open valve 9 (18), and close valve 10 (19) and valve 11 (20). ① Turn on the condensate pump (8), and the condensate will not enter the heat pump (1); ② Close valve 12 (21) and stop the cooling water pump (9), and the cooling water will not enter the heat pump (1); ③ Open valve 15 (24) and the heat pump (1) will be put into operation; During summer operation: ① Open valve 1 (10), valve 2 (11), and valve 4 (13), close valve 3 (12), turn on the circulating water pump (6) to introduce circulating water into the system, and close valve 1 (10) after the circulating water pipeline is full of water; ② Close valve 5 (14) and valve 7 (16) to stop the heating network water pump. (7); ③ Close valve nine (18), open valve ten (19) and valve eleven (20), start condensate pump (8), and condensate enters heat pump (1); ④ Open valve twelve (21), valve thirteen (22), and valve fourteen (23), start cooling water pump (9), introduce cooling water into the system, and close valve twelve (21) after the cooling water pipeline is full of water; ⑤ Open valve fifteen (24), and heat pump (1) is put into operation; When heat pump (1) is out of operation: ① Close valve fifteen (24), and heat pump (1) is out of operation; ② Open valve one ( 10) and valve three (12), close valve two (11) and valve four (13), start circulating water pump (6), and start circulating water system operation mode; ③ open valve five (14) and valve seven (16), close valve six (15) and valve eight (17), start heating network water pump (7), and start heating network water system operation mode; ④ open valve nine (18), close valve ten (19) and valve eleven (20), start condensate pump (8), and start condensate system operation mode; ⑤ close valve twelve (21), and cooling water pump (9) exits operation.

2. The operation method of the waste steam utilization system of the gas-fired steam combined cycle unit according to claim 1, characterized in that, The driving steam of the heat pump (1) comes from the steam turbine extraction steam; the condenser (2) cools the exhaust steam of the steam turbine, and the cooling medium is circulating water. The circulating water pump (6) can send the circulating water into the condenser (2); the high-temperature water of the heat user (3) comes from the heat pump (1), and the heating network water pump (7) can send the heating network water into the heat user (3); the regenerative heater (4) uses the steam turbine extraction steam to heat the condensate, and the condensate pump (8) can send the water condensed from the exhaust steam into the heat pump (1); the air heat exchanger (5) reduces the temperature of the air entering the compressor by cooling water, and the cooling water pump (9) can send the cooling water into the air heat exchanger (5).

3. The operation method of the waste steam utilization system of a gas-fired combined cycle unit according to claim 1 or 2, characterized in that, The heat from the exhaust steam of the steam turbine is released to the circulating water in the condenser (2). The heated circulating water enters the heat pump (1) through the circulating water pipeline, where it releases heat. The cooled circulating water then re-enters the condenser (2). The return water from the heat user (3) enters the heat pump (1) through the heating network water pipeline, where it absorbs heat. The heated hot water is then supplied to the heat user (3). The water condensed from the exhaust steam of the steam turbine in the condenser (2) enters the heat pump (2) through the condensate pipeline. 1) Heat is absorbed in the heat pump (1), and the heated condensate enters the regenerator (4); the inlet air of the air heat exchanger (5) exchanges heat with the cooling water in the air heat exchanger (5), and the heated cooling water enters the heat pump (1) through the cooling water pipeline, absorbs heat in the heat pump (1), and the cooled water re-enters the air heat exchanger (5); the driving steam source of the heat pump (1) releases heat in the heat pump (1), and the condensed water returns to the regenerator (4).

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