Combined cycle power plant power augmentation system and method

Abstract

The present application relates to power generation technology field, disclose a combined cycle unit power improving power generation system and method, the power generation system includes gas turbine, waste heat boiler, steam turbine and organic rankine cycle, waste heat boiler is connected with gas turbine, steam turbine is connected with waste heat boiler, organic rankine cycle is connected with steam turbine and waste heat boiler, the present application is coupled with waste heat boiler in combined cycle unit by organic rankine cycle, when gas turbine runs power generation, the flue gas discharged into waste heat boiler and working fluid water heat exchange, working fluid water is heated to steam, wherein the low temperature low pressure steam can be exchanged with the organic working medium in organic rankine cycle, the low temperature organic working medium is heated to high temperature high pressure organic working medium, and high temperature high pressure organic working medium is used to drive generator to run power generation, also heated the steam in waste heat boiler temperature is lower, so that its energy is efficiently utilized, steam and organic working medium jointly drive generator power generation further improves the efficiency of power generation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power generation, in particular to a combined cycle unit power increasing power generation system and method. BACKGROUND

[0002] The combined cycle power plant (CCPP) is mainly to pressurize the natural gas or other combustible gas through the gas compressor, mix and burn with the air sent to the combustion chamber, generate high-temperature and high-pressure gas, expand the gas through the gas turbine to do work, drive the gas turbine to rotate at high speed with the compressor and external load, and guide the exhaust gas discharged from the gas turbine to the waste heat boiler to generate high-temperature and high-pressure steam to drive the steam turbine, together with the gas turbine, to drive the generator to generate electricity.

[0003] In the prior art, the low-temperature working water is exchanged for high-temperature and high-pressure steam in the waste heat boiler in multiple stages. The steam generated in the low-temperature interval of the waste heat boiler has low temperature and pressure, which is not enough to efficiently drive the steam turbine to operate, so that part of the energy in the waste heat boiler cannot be fully used, resulting in low power generation efficiency. SUMMARY

[0004] Therefore, the present application provides a combined cycle unit power increasing power generation system and method to solve the problem that part of the energy in the waste heat boiler cannot be fully used, resulting in low power generation efficiency.

[0005] In a first aspect, the present application provides a combined cycle unit power increasing power generation system, comprising:

[0006] A gas turbine adapted to drive a generator to generate electricity;

[0007] A waste heat boiler connected with the gas turbine and adapted to recover heat in flue gas of the gas turbine;

[0008] A steam turbine connected with the waste heat boiler and adapted to drive a generator to generate electricity, and a circulation loop is formed between the waste heat boiler and the steam turbine;

[0009] An organic Rankine cycle connected with the steam turbine and the waste heat boiler and adapted to drive a generator to generate electricity.

[0010] Beneficial effects: By coupling the organic Rankine cycle with the waste heat boiler in the combined cycle unit, when the gas turbine operates to generate electricity, the exhaust flue gas enters the waste heat boiler to exchange heat with the working water, and the working water is heated into steam. The low-temperature and low-pressure steam can exchange heat with the organic working medium in the organic Rankine cycle, and the low-temperature organic working medium is heated into high-temperature and high-pressure organic working medium. The high-temperature and high-pressure organic working medium is used to drive the generator to operate to generate electricity, so that the energy of the low-temperature steam in the waste heat boiler can be fully utilized, and the efficiency of electricity generation is further improved by the organic working medium driving the generator to generate electricity.

[0011] In an alternative embodiment, the organic Rankine cycle comprises:

[0012] The first heat exchanger is connected with the steam turbine and the waste heat boiler.

[0013] The second heat exchanger is connected with the waste heat boiler and the steam turbine.

[0014] The expander is connected with the first heat exchanger and the waste heat boiler, and the expander is adapted to drive the generator to generate electricity.

[0015] The cooler is connected with the expander and the first heat exchanger, and a circulating medium is arranged in a circulating loop formed by the first heat exchanger, the expander and the cooler.

[0016] Beneficial effects: By arranging the first heat exchanger, the working water output after driving the steam turbine still contains a lot of heat. The heat in the working water is used to exchange heat with the organic working medium in the organic Rankine cycle, so that the temperature of the low-temperature organic working medium is increased. The working water after heat exchange can be circulated into the waste heat boiler for heat exchange again. The second heat exchanger is arranged to exchange heat again between the low-temperature and low-pressure steam working medium generated in the waste heat boiler and the organic working medium after heat exchange in the first heat exchanger. The organic working medium after heat exchange drives the expander to operate, so as to drive the generator to generate electricity. The organic working medium enters the cooler from the expander to be cooled again, and participates in the circulation in the organic Rankine cycle. The reheat steam generated in the waste heat boiler can also be used to drive the expander together with the organic working medium. Therefore, the energy of the high-temperature and low-pressure steam generated in the waste heat boiler can be fully utilized to generate electricity, and the output of the waste heat boiler is increased.

[0017] In an alternative embodiment, the cooler comprises:

[0018] The air cooler is connected with the expander.

[0019] The cryogenic pump is connected with the air cooler and the first heat exchanger.

[0020] Beneficial effect: By setting the air cooler, the organic working medium output from the expander can be rapidly cooled, and the cooled organic working medium is input into the cryogenic pump for further cooling and cooling to participate in the cycle.

[0021] In an alternative embodiment, the power-increased power generation system of the combined cycle unit further comprises:

[0022] The third heat exchanger is connected with the second heat exchanger, the waste heat boiler and the steam turbine.

[0023] Beneficial effect: By setting the third heat exchanger, the heated steam in the second heat exchanger can be heated again and input into the steam turbine for operation and power generation or input into the waste heat boiler for further heat exchange, thereby increasing the temperature of the steam and fully utilizing the energy in the steam.

[0024] In an alternative embodiment, the organic Rankine cycle further comprises:

[0025] The fourth heat exchanger is connected with the second heat exchanger, the expander, the waste heat boiler and the third heat exchanger.

[0026] Beneficial effect: By setting the fourth heat exchanger, the steam in the waste heat boiler can be further heat-exchanged with the organic working medium, thereby further increasing the temperature and pressure of the organic working medium. The heat-exchanged steam can be input into the steam turbine for operation and power generation or input into the waste heat boiler for further heat exchange, thereby fully utilizing the energy in the steam.

[0027] In an alternative embodiment, the steam turbine comprises:

[0028] The high-pressure cylinder forms a circulation loop with the waste heat boiler;

[0029] The low-pressure cylinder is connected with the third heat exchanger and the first heat exchanger.

[0030] Beneficial effect: The high-temperature and high-pressure steam generated in the waste heat boiler can be used to drive the high-pressure cylinder to operate and generate power. The steam output from the high-pressure cylinder is input into the waste heat boiler for heat exchange. The heated steam in the third heat exchanger has a higher temperature and can be used to drive the low-pressure cylinder to operate and generate power, thereby fully utilizing the steam energy at different temperatures in the waste heat boiler for power generation.

[0031] In an alternative embodiment, the waste heat boiler comprises:

[0032] The fifth heat exchanger is connected with the first heat exchanger and the second heat exchanger;

[0033] The sixth heat exchanger is connected with the fourth heat exchanger;

[0034] The reheater is connected with the expander, the high-pressure cylinder and the third heat exchanger.

[0035] Beneficial effects: The flue gas output by the gas turbine exchanges heat with the reheater, the sixth heat exchanger and the fifth heat exchanger in the waste heat boiler in turn, the reheater exchanges heat with the flue gas at a higher temperature to generate steam at a higher temperature, which is used to drive the expander to operate to generate power, at the same time, the steam at a lower temperature in the high-pressure cylinder and the third heat exchanger returns to the reheater to exchange heat again, the flue gas after heat exchange continues to exchange heat with the fifth heat exchanger and the sixth heat exchanger, the steam at a lower temperature exchanges heat with the second heat exchanger and the fourth heat exchanger, and the working water in the first heat exchanger returns to the sixth heat exchanger to participate in the circulation, so that the heat in the flue gas is fully utilized to exchange heat with the working water, and the steam energy after heat exchange is further fully used for heat exchange of the organic Rankine cycle and power generation.

[0036] In an alternative embodiment, the waste heat boiler further comprises:

[0037] A superheater connected with the high-pressure cylinder.

[0038] Beneficial effects: By arranging the superheater, part of the heat in the flue gas can be absorbed, and the heat in the flue gas is exchanged with the working water to generate steam to drive the high-pressure cylinder to operate to generate power.

[0039] In an alternative embodiment, the waste heat boiler further comprises:

[0040] An economizer;

[0041] A steam drum connected with the economizer and the superheater.

[0042] Beneficial effects: By arranging the economizer, the heat in the flue gas can be further absorbed, and the steam generated in the economizer is input into the superheater.

[0043] In a second aspect, the application also provides a power generation method for improving the power of a combined cycle unit, which adopts the power generation system for improving the power of a combined cycle unit described above, and the power generation method comprises:

[0044] Inputting a circulating medium into the organic Rankine cycle;

[0045] Starting the gas turbine to drive the generator to generate power, the gas turbine conveying flue gas into the waste heat boiler to exchange heat with the working water, the working water after heat exchange being heated to steam, the steam driving the steam turbine to operate to generate power;

[0046] The circulating medium exchanging heat with the steam in the waste heat boiler to form high-pressure gas driving the generator to generate power;

[0047] The high-pressure gas after power generation being condensed and liquefied to participate in the circulation again.

[0048] Because the combined cycle unit power generation method adopts the combined cycle unit power generation system for improving power, has the same effect with the combined cycle unit power generation system for improving power, here is not tedious. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0050] Figure 1 A schematic diagram of a combined cycle unit power generation system for improving power according to an embodiment of the present application;

[0051] Figure 2 A flow chart of a combined cycle unit power generation method for improving power according to an embodiment of the present application.

[0052] BRIEF DESCRIPTION OF DRAWINGS

[0053] 1, gas turbine;

[0054] 2, waste heat boiler; 201, fifth heat exchanger; 202, sixth heat exchanger; 203, reheater; 2031, first reheater; 2032, second reheater; 204, superheater; 2041, first superheater; 2042, second superheater; 205, coal economizer; 206, steam drum;

[0055] 3, steam turbine; 301, high pressure cylinder; 302, low pressure cylinder;

[0056] 4, organic Rankine cycle; 401, first heat exchanger; 402, second heat exchanger; 403, expander; 404, cooler; 4041, air cooler; 4042, cryogenic pump; 405, fourth heat exchanger; 406, storage tank;

[0057] 5, third heat exchanger;

[0058] 6, separator;

[0059] 7, generator. DETAILED DESCRIPTION

[0060] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of the present application.

[0061] The embodiments of the present application are described below with reference to the drawings. Figure 1 And Figure 2 The embodiments of the present application are described below with reference to the drawings.

[0062] According to the embodiments of the present application, in one aspect, a power generation system for improving power of a combined cycle unit is provided, which comprises a gas turbine 1, a waste heat boiler 2, a steam turbine 3 and an organic Rankine cycle 4. The gas turbine 1 is adapted to drive a generator 7 to generate power. The waste heat boiler 2 is connected with the gas turbine 1 and is adapted to recover heat in flue gas of the gas turbine 1. The steam turbine 3 is connected with the waste heat boiler 2 and is adapted to drive the generator 7 to generate power. A circulation loop is formed between the waste heat boiler 2 and the steam turbine 3. The organic Rankine cycle 4 is connected with the steam turbine 3 and the waste heat boiler 2 and is adapted to drive the generator 7 to generate power.

[0063] In the embodiments, the circulating working medium in the organic Rankine cycle 4 is not specifically limited. In order to meet the actual situation, the circulating working medium can be a high molecular weight organic fluid, such as butane, propane, ammonia, etc. Since the boiling point of the organic fluid is generally below 0℃, the organic fluid can be heated by a relatively low temperature to expand and do work to generate power. In the embodiments, the low-temperature steam in the steam turbine 3 and the waste heat boiler 2 is used to heat and vaporize the organic fluid to form heated organic vapor having thermodynamic energy, and the thermodynamic energy in the heated organic vapor is converted into mechanical energy operably coupled to a turbine in a closed loop system. In some other embodiments not shown, a low-temperature heat source such as geothermal energy can be used to heat the organic fluid to fully utilize the power generation capacity of the organic fluid in a low-temperature range.

[0064] Specifically, in the embodiments, the circulating working medium in the organic Rankine cycle 4 is liquid ammonia. Since the boiling point of liquid ammonia is -34℃, the liquid ammonia is easy to vaporize and expand after heat exchange. In the embodiments, the liquid ammonia can be stored in a storage tank 406, and a heat exchanger is arranged in the storage tank 406 to exchange heat between liquefied natural gas (LNG) input into the gas turbine 1 at about -170℃ and the liquid ammonia, so as to keep the liquid state of the ammonia and increase the temperature of the liquefied natural gas input into the gas turbine 1.

[0065] By coupling the organic Rankine cycle 4 with the waste heat boiler 2 in the combined cycle unit, when the gas turbine 1 operates to generate electricity, the exhaust flue gas enters the waste heat boiler 2 to exchange heat with the working water, and the working water is heated to steam, wherein the low-temperature and low-pressure steam can exchange heat with the organic working medium in the organic Rankine cycle 4 to heat the low-temperature organic working medium to high-temperature and high-pressure organic working medium, and the high-temperature and high-pressure organic working medium is used to drive the generator 7 to operate to generate electricity, so that the energy of the low-temperature steam in the waste heat boiler 2 is fully utilized, and the organic working medium drives the generator 7 to generate electricity, further improving the efficiency of electricity generation.

[0066] In one embodiment, the organic Rankine cycle 4 comprises a first heat exchanger 401, a second heat exchanger 402, an expander 403 and a cooler 404, the first heat exchanger 401 is connected with the steam turbine 3 and the waste heat boiler 2, the second heat exchanger 402 is connected with the waste heat boiler 2 and the steam turbine 3, the expander 403 is connected with the first heat exchanger 401 and the waste heat boiler 2, the expander 403 is suitable for driving the generator 7 to generate electricity, and the cooler 404 is connected with the expander 403 and the first heat exchanger 401, a circulating loop is formed between the first heat exchanger 401, the expander 403 and the cooler 404, and a circulating medium is arranged in the circulating loop.

[0067] By arranging the first heat exchanger 401, the working water output after driving the steam turbine 3 still contains a lot of heat, and the heat in the working water is used to exchange heat with the organic working medium in the organic Rankine cycle 4 to increase the temperature of the low-temperature organic working medium to about 40℃, and the working water after heat exchange can be recycled into the waste heat boiler 2 for heat exchange again, and the second heat exchanger 402 arranged can exchange heat again between the low-temperature and low-pressure steam working medium of about 250℃ and 5bar generated in the waste heat boiler 2 and the organic working medium after heat exchange in the first heat exchanger 401, the organic working medium after heat exchange drives the expander 403 to operate, thereby driving the generator 7 to generate electricity, and the organic working medium enters the cooler 404 from the expander 403 to be cooled again, participates in the circulation in the organic Rankine cycle 4, and the reheat steam generated in the waste heat boiler 2 can also be used to drive the expander 403 to operate, so that the energy of the high-temperature and low-pressure steam generated in the waste heat boiler 2 can be fully utilized to generate electricity, and the output of the waste heat boiler is increased.

[0068] In one embodiment, the cooler 404 comprises an air cooler 4041 and a deep cooling pump 4042, the air cooler 4041 is connected with the expander 403, and the deep cooling pump 4042 is connected with the air cooler 4041 and the first heat exchanger 401.

[0069] By arranging the air cooler 4041, the organic working medium output from the expander 403 can be rapidly cooled, and the cooled organic working medium is input into the deep cooling pump 4042 for further cooling and participating in the circulation.

[0070] In one embodiment, the combined cycle unit power increasing power generation system further comprises a third heat exchanger 5 connected with the second heat exchanger 402, the waste heat boiler 2 and the steam turbine 3. By arranging the third heat exchanger 5, the steam after heat exchange in the second heat exchanger 402 can be heated again and then input into the steam turbine 3 to generate power or input into the waste heat boiler 2 to be heat exchanged again, so that the energy in the steam can be fully utilized.

[0071] In the embodiment, the third heat exchanger 5 is not limited, and can be an electric heater or a heater using solar energy or geothermal energy. The temperature of the steam after heat exchange in the second heat exchanger 402 is reduced to about 200℃, and the steam can be heated to about 320℃ by the third heat exchanger 5 and then used to drive the steam turbine 3.

[0072] In one embodiment, the organic Rankine cycle 4 further comprises a fourth heat exchanger 405 connected with the second heat exchanger 402, the expander 403, the waste heat boiler 2 and the third heat exchanger 5.

[0073] By arranging the fourth heat exchanger 405, the steam at about 320℃ and 40bar in the waste heat boiler 2 can be heat exchanged with the organic working medium to about 300℃, so as to further increase the temperature and pressure of the organic working medium. The temperature of the steam after heat exchange is reduced to about 300℃, and the steam can be heated again in the third heat exchanger 5 and then input into the steam turbine 3 to generate power or input into the waste heat boiler 2 to be heated to about 400℃ and 40bar to be heat exchanged again to generate super-saturated steam, so that the energy in the steam can be fully utilized.

[0074] In one embodiment, the steam turbine 3 comprises a high-pressure cylinder 301 and a low-pressure cylinder 302. The high-pressure cylinder 301 and the waste heat boiler 2 form a circulation loop, and the low-pressure cylinder 302 is connected with the third heat exchanger 5 and the first heat exchanger 401.

[0075] The high-temperature and high-pressure steam generated in the waste heat boiler 2 can be used to drive the high-pressure cylinder 301 to generate power. The steam output from the high-pressure cylinder 301 is input into the waste heat boiler 2 again to be heat exchanged. The steam heated in the third heat exchanger 5 has a temperature of about 320℃ and can be used to drive the low-pressure cylinder 302 to generate power, so that the steam energy at different temperatures in the waste heat boiler 2 can be fully utilized to generate power.

[0076] In one embodiment, the waste heat boiler 2 comprises a fifth heat exchanger 201, a sixth heat exchanger 202 and a reheater 203. The fifth heat exchanger 201 is connected with the first heat exchanger 401 and the second heat exchanger 402. The sixth heat exchanger 202 is connected with the fourth heat exchanger 405. The reheater 203 is connected with the expander 403, the high-pressure cylinder 301 and the third heat exchanger 5.

[0077] The flue gas output by the gas turbine 1 exchanges heat with the reheater 203, the sixth heat exchanger 202 and the fifth heat exchanger 201 in the waste heat boiler 2 in sequence. The reheater 203 exchanges heat with the flue gas at a higher temperature to generate steam at a higher temperature, which is used to drive the expander 403 to operate to generate power. Meanwhile, the steam at a lower temperature in the high-pressure cylinder 301 and the third heat exchanger 5 returns to the reheater 203 again to exchange heat. The flue gas after heat exchange continues to exchange heat with the fifth heat exchanger 201 and the sixth heat exchanger 202 to generate steam at a lower temperature, which exchanges heat with the second heat exchanger 402 and the fourth heat exchanger 405. The working water in the first heat exchanger 401 returns to the sixth heat exchanger 202 to participate in the circulation, so that the heat in the flue gas is fully utilized to exchange heat with the working water, and the energy of the steam after heat exchange is further fully utilized to exchange heat with the organic Rankine cycle 4 and generate power.

[0078] In the embodiment, the reheater 203 is arranged on the side of the flue gas inlet in the waste heat boiler 2, and the fifth heat exchanger 201 is arranged on the side away from the gas turbine 1 in the waste heat boiler 2. The flue gas at about 600℃ after combustion of the gas turbine 1 exchanges heat with the working water in the waste heat boiler 2 in sequence with the reheater 203, the sixth heat exchanger 202 and the fifth heat exchanger 201. The temperature of the flue gas after heat exchange gradually decreases, so that the steam output by the reheater 203 after heat exchange is at about 580℃, which is used to drive the expander 403 to work, and further drive the generator 7 to operate to generate power. The steam output by the sixth heat exchanger 202 after heat exchange is at about 320℃ and has a pressure of 40 bar. The steam output by the fifth heat exchanger 201 after heat exchange is at about 250℃ and has a pressure of about 5 bar.

[0079] The reheater 203 includes the first reheater 2031 and the second reheater 2032 connected in series. The first reheater 2031 is connected with the high-pressure cylinder 301 and the third heat exchanger. The second reheater 2032 is connected with the expander 403. The second reheater 2032 outputs high-temperature steam at about 580℃ after heat exchange with the flue gas.

[0080] In one embodiment, the waste heat boiler 2 further includes the superheater 204 connected with the high-pressure cylinder 301. The superheater 204 includes the first superheater 2041 and the second superheater 2042 connected in series. The first superheater 2041 is arranged close to the sixth heat exchanger 202. The second superheater 2042 is arranged between the first reheater 2031 and the second reheater 2032. The second superheater 2042 is connected with the high-pressure cylinder 301.

[0081] The first superheater 2041 uses the flue gas with a lower temperature to exchange heat with the working medium water to generate steam, which is input into the second superheater 2042, and then exchanges heat with the flue gas with a higher temperature to generate high-temperature and high-pressure steam, which drives the high-pressure cylinder 301 to operate and further drives the generator 7 to generate electricity. The first superheater 2041 arranged downstream of the first reheater 2031 and the second superheater 2042 arranged downstream of the second reheater 2032 can absorb part of the heat in the flue gas, so as to avoid damage to the reheater 203 due to the excessively large temperature difference between the inside and outside of the reheater 203 when the gas turbine 1 starts.

[0082] By arranging the superheater 204, part of the heat in the flue gas can be absorbed, and the heat in the flue gas is exchanged with the working medium water to generate steam, which drives the high-pressure cylinder 301 to operate and generate electricity, thereby avoiding damage to the downstream reheater 203 in the waste heat boiler 2 caused by the flue gas with excessively high temperature.

[0083] In an embodiment, the waste heat boiler 2 further comprises an economizer 205 and a steam drum 206, and the steam drum 206 is connected with the economizer 205 and the superheater 204. By arranging the economizer 205, the heat in the flue gas can be further absorbed, and the steam generated in the economizer 205 is input into the superheater 204.

[0084] According to the embodiment of the present application, in another aspect, a power generation method for improving the power of a combined cycle unit is also provided, which uses the power generation system for improving the power of the combined cycle unit in the embodiment. The power generation method comprises:

[0085] The circulating medium is input into the organic Rankine cycle 4;

[0086] Specifically, in the embodiment, the renewable energy can be used to cool, pressurize and liquefy the ammonia gas for storage, and then the liquid ammonia is used as the circulating medium of the organic Rankine cycle 4.

[0087] The gas turbine 1 is started to drive the generator 7 to generate electricity, and the gas turbine 1 delivers the flue gas to the waste heat boiler 2 to exchange heat with the working medium water, and the working medium water after heat exchange is heated to generate steam, which drives the steam turbine 3 to operate and generate electricity;

[0088] The circulating medium exchanges heat with the steam in the waste heat boiler 2 to form high-pressure gas, which drives the generator 7 to generate electricity;

[0089] The high-pressure gas after electricity generation is condensed and liquefied to participate in the circulation again.

[0090] Specifically, the gas turbine 1 is started at the same time as the organic Rankine cycle 4, the organic cycle medium can be used as the cold end cooling condensate water of the combined cycle power plant, the low-temperature steam output from the low-pressure cylinder 302 is exchanged with liquid ammonia, the low-temperature steam is cooled to condensate water and returned to the waste heat boiler 2 for heat exchange, the liquid ammonia is exchanged with the high-temperature and high-pressure steam output from the reheater 203 of the waste heat boiler 2 in the first heat exchanger 401, the second heat exchanger 402 and the fourth heat exchanger 405, and the high-temperature and high-pressure ammonia gas is mixed with the high-temperature and high-pressure steam to enter the expander 403 to generate power, the same pressure is formed as the "ammonia gas-steam" mixed power generation working medium, the ammonia gas is cooled by the cooler 404 and returned to the storage tank 406 for storage, and the water vapor is recovered as condensate water.

[0091] When the power generation capacity needs to be increased due to peak regulation, the power generated by the expander 403 driving the generator 7 can be used as the power source of the third heat exchanger 5, so that the low-temperature and low-pressure steam after heat exchange is heated and input into the low-pressure cylinder 302 to operate and generate power, and the medium-temperature and medium-pressure steam is heated and returned to the first reheater 2031 for heat exchange, thereby improving the output power of the unit.

[0092] When the required amount of ammonia is insufficient, the first heat exchanger 401, the second heat exchanger 402 and the fourth heat exchanger 405 are closed, the heating of ammonia in the organic Rankine cycle 4 is stopped, and the third heat exchanger 5 is switched to be heated by electricity to continuously heat the low-pressure and medium-pressure steam, thereby meeting the need to increase the power generation capacity of the unit.

[0093] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A power generation system for increasing power of a combined cycle unit, characterized by, The application relates to a combined cycle unit power increasing power generation system and a power generation method. The combined cycle unit power increasing power generation system comprises a gas turbine (1) adapted to drive a generator (7) to generate power; a waste heat boiler (2) connected with the gas turbine (1) and adapted to recover heat in flue gas of the gas turbine (1); a steam turbine (3) connected with the waste heat boiler (2) and adapted to drive the generator (7) to generate power, wherein a circulating loop is formed between the waste heat boiler (2) and the steam turbine (3), and the steam turbine (3) comprises a high-pressure cylinder (301) and a low-pressure cylinder (302), and a circulating loop is formed between the high-pressure cylinder (301) and the waste heat boiler (2); an organic Rankine cycle (4) connected with the steam turbine (3) and the waste heat boiler (2) and adapted to drive the generator (7) to generate power, wherein the organic Rankine cycle (4) comprises a first heat exchanger (401), a second heat exchanger (402), an expander (403), a cooler (404) and a fourth heat exchanger (405), the first heat exchanger (401) is connected with the steam turbine (3) and the waste heat boiler (2), the second heat exchanger (402) is connected with the waste heat boiler (2) and the steam turbine (3), the expander (403) is connected with the first heat exchanger (401) and the waste heat boiler (2), the expander (403) is adapted to drive the generator (7) to generate power, the cooler (404) is connected with the expander (403) and the first heat exchanger (401), a circulating loop is formed between the first heat exchanger (401), the expander (403) and the cooler (404), and a circulating medium is arranged in the circulating loop, and the fourth heat exchanger (405) is connected with the second heat exchanger (402), the expander (403), the waste heat boiler (2) and a third heat exchanger (5); and the third heat exchanger (5) is connected with the second heat exchanger (402), the waste heat boiler (2) and the steam turbine (3), and the low-pressure cylinder (302) is connected with the third heat exchanger (5) and the first heat exchanger (401). The cooler (404) comprises an air cooler (4041) connected with the expander (403) and a cryogenic pump (4042) connected with the air cooler (4041) and the first heat exchanger (401). The waste heat boiler (2) comprises a fifth heat exchanger (201) connected with the first heat exchanger (401) and the second heat exchanger (402), a sixth heat exchanger (202) connected with the fourth heat exchanger (405), and a reheater (203) connected with the expander (403), the high-pressure cylinder (301) and the third heat exchanger (5). The waste heat boiler (2) further comprises a superheater (204) connected with the high-pressure cylinder (301). The waste heat boiler (2) further comprises an economizer (205) and a steam drum (206) connected with the economizer (205) and the superheater (204).

2. The power-increasing power generation system for a combined cycle unit according to claim 1, characterized by, The power generation method comprises the following steps: The combined cycle unit power increasing power generation system and the power generation method have the advantages that the organic Rankine cycle is arranged in the steam turbine, the waste heat boiler and the third heat exchanger, the expander is connected with the first heat exchanger and the waste heat boiler, the circulating loop is formed between the first heat exchanger, the expander and the cooler, the circulating medium is arranged in the circulating loop, the fourth heat exchanger is connected with the second heat exchanger, the expander, the waste heat boiler and the third heat exchanger, the third heat exchanger is connected with the second heat exchanger, the waste heat boiler and the steam turbine, the low-pressure cylinder is connected with the third heat exchanger and the first heat exchanger, the waste heat boiler is connected with the first heat exchanger and the second heat exchanger, the reheater is connected with the expander, the high-pressure cylinder and the third heat exchanger, the superheater is connected with the high-pressure cylinder, the economizer is arranged in the waste heat boiler, and the steam drum is connected with the economizer and the superheater, so that the waste heat of the steam turbine and the waste heat of the flue gas of the gas turbine are recovered, the waste heat is used to drive the expander to generate power, the power generation efficiency is improved, the waste heat is effectively utilized, the waste heat is recovered, the power generation efficiency is improved, the waste heat is effectively utilized, and the power generation cost is reduced. ​ 3. The power-increasing power generation system for a combined cycle unit according to claim 1, characterized by, ​ ​ ​ ​ 4. The power-increasing power generation system for a combined cycle unit according to claim 3, characterized by, ​ ​ 5. The power-increasing power generation system for a combined cycle unit according to claim 4, characterized by, ​ ​ ​ 6. A method of increasing power generation in a combined cycle unit, the method comprising: ​ Inputting circulating medium into the organic Rankine cycle (4); Starting the gas turbine (1) to drive the generator (7) to generate electricity, and the gas turbine (1) delivers flue gas to the waste heat boiler (2) to exchange heat with working water, and the working water after heat exchange is heated to steam, and the steam drives the steam turbine (3) to operate to generate electricity; The circulating medium exchanges heat with the steam in the waste heat boiler (2) to form high-pressure gas to drive the generator (7) to generate electricity; The high-pressure gas after electricity generation is condensed and liquefied to participate in the cycle again.

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