Gas-steam combined cycle water vapor heat-carrying type flue gas waste heat recovery heat supply system

Abstract

A steam heat-carrying type flue gas waste heat recovery heat supply system of a combustion-steam combined cycle belongs to the technical field of combustion-steam combined cycle and clean heat supply and comprises an intermediate water heat exchanger 23, a fresh air inlet device 25, a total heat air pre-heater 26, a fresh air superheater 27, a flue gas waste heat spray tower 35 (divided into a flue gas low-temperature spray section 33 and a flue gas high-temperature spray section 34) and the like. Flue gas at an outlet of a waste heat boiler is fed into a flue gas waste heat spraying tower 35 to be cooled and then returns to a chimney 10, medium water outlet water of a flue gas high-temperature spraying section 34 is fed into a medium water heat exchanger 23 to heat return water of a heat supply network, one path of medium water outlet water is returned for circulation, and the other path of medium water outlet water is fed into a total heat air pre-heater 26 to heat, humidify and superheat inlet gas of a gas turbine and then returns to a flue gas low-temperature spraying section 33. Humidified water vapor of gas turbine inlet gas reduces the oxygen content of the inlet gas, the water vapor serves as a heat-carrying medium, latent heat of vaporization and the energy grade of the latent heat of vaporization in smoke are improved, and then the outlet water temperature of intermediate water is increased so as to heat return water of a heat supply network.

Description

Technical Field

[0001] The utility model relates to a water vapor heat-carrying flue gas waste heat recovery and heating system for a combined combustion and steam cycle, belonging to the technical field of combined combustion and steam cycle and clean heating. Background Art

[0002] The combined cycle of combustion and steam uses natural gas to burn and drive gas turbines to generate electricity. Its high-temperature flue gas is sent to the waste heat boiler to generate high-parameter steam and drive the steam turbine to generate electricity. In view of the relatively high price of gas, the combined cycle of combustion and steam usually produces heat and power, and uses steam extraction from steam turbines for heating, including industrial steam supply and urban heating. In order to further improve energy utilization efficiency and reduce losses at both ends, in recent years, the systems in the northern heating areas have begun to recover the waste heat of steam from steam turbines and flue gas for heating. The former usually uses a condenser to heat the return water of the heat network and eliminate the loss at the cold end; the latter mostly uses an absorption heat pump or an electric compression heat pump to recover the waste heat of flue gas, achieving deep heat recovery (the flue gas temperature is reduced to about 30°C), which is used to heat the return water of the heat network and expand the heating capacity.

[0003] At present, the problems of flue gas waste heat recovery include: when using absorption heat pump, a large amount of steam turbine extraction is required for driving, and 1.5-2.0t / h of steam is usually required to recover 1MW of flue gas waste heat, which will greatly reduce the power generation and economic benefits of the combined cycle of combustion and steam, and seriously affect the flexibility of the operation of the cogeneration system; when using compression heat pump, a large amount of driving power is required, which greatly increases the operating energy consumption of the waste heat recovery system, seriously affects the online power and its economy. Therefore, the two commonly used heat pump waste heat recovery methods are not ideal flue gas waste heat recovery methods for the combined cycle of combustion and steam.

[0004] The series of patented technologies of "water vapor heat carrier flue gas waste heat recovery and deep coordinated treatment of pollutants" jointly developed by Tsinghua University and Beijing Tsinghua Tiangong Energy Technology Research Institute can be used for coal-fired boilers, gas boilers, biomass boilers and waste incinerators, etc., using combustion air full heat air preheater to replace heat pumps to achieve deep heat recovery of flue gas and near-zero emissions of pollutants. However, this technical method has not yet been applied to the combined cycle system of combustion and steam, and the technical and production management personnel of power plants generally oppose the use of this technical method. The main reasons are: it is generally believed that gas turbines usually have the highest power generation load and efficiency when the intake temperature is 10-15℃, and the increase in temperature will lead to a significant reduction in the load of the gas turbine and a decrease in efficiency; power plants generally reflect that their system's power generation in summer is obviously insufficient, so they firmly oppose heating the intake air to above 30-40℃ in winter.

[0005] Therefore, it is necessary to fundamentally solve the above problems in order to more efficiently recover flue gas waste heat and expand heating capacity. Utility Model Content

[0006] The purpose and task of the utility model is to recover waste heat from the above-mentioned combined steam and combustion cycle system, expand heating capacity, improve thermal efficiency of the entire plant, further control flue gas pollutants and other problems, and adopt an air intake heating and humidification method with a full-heat air preheater to achieve deep waste heat recovery of flue gas, low-nitrogen combustion and near-zero pollutant emissions.

[0007] The specific description of the utility model is: a steam-heat-carrying flue gas waste heat recovery and heating system of a combined combustion and steam cycle, comprising a conventional combined combustion and steam cycle power generation system and a flue gas waste heat recovery and heating system, wherein the conventional combined combustion and steam cycle power generation system comprises a grid-connected device 1, a gas turbine generator 2, a compressor 3, a cold air inlet device 4, a gas cabinet 5, a gas turbine 6, a waste heat boiler 7, a waste boiler outlet section 8, a flexible connection 9, a chimney 10, a steam turbine generator 11, a steam turbine 12, a condenser 14, a feed water pump 16, a cooling tower 17 and wind and smoke pipes, water vapor pipes and cables connected to each other, characterized in that the flue gas waste heat recovery and heating system comprises an intermediate water heat exchange The device 23, the intermediate water pump 24, the fresh air inlet device 25, the full hot air preheater 26, the fresh air superheater 27, the hot air regulating valve 28, the bypass smoke outlet section 30, the smoke regulating valve 31, the bypass smoke return section 32, the smoke waste heat spray tower 35, and the alkali adding device 36, wherein the smoke waste heat spray tower 35 includes a smoke low temperature spray section 33 and a smoke high temperature spray section 34; wherein the lower lateral air inlet of the full hot air preheater 26 is connected to the fresh air inlet device 25, the air inlet of the fresh air inlet device 25 is communicated with the ambient air A, the middle part of the full hot air preheater 26 is a heat exchange zone structure for air and spray water, the air outlet of the full hot air preheater 26 is connected to the air inlet of the fresh air superheater 27, and the fresh air The water inlet of the fresh air superheater 27 is connected to the high-temperature water inlet R1, the water outlet of the fresh air superheater 27 is connected to the high-temperature water outlet R2, and the air outlet of the fresh air superheater 27 is connected to the air inlet of the compressor 3 through the hot air regulating valve 28; the air inlet of the compressor 3 is also connected to the ambient air A through the cold air inlet device 4, the high-pressure exhaust port of the compressor 3 is connected to the air inlet of the gas turbine 6, the gas inlet of the gas turbine 6 is connected to the gas supply port of the gas cabinet 5, the smoke exhaust port of the gas turbine 6 is connected to the high-temperature smoke inlet of the waste heat boiler 7, the low-temperature smoke outlet of the waste heat boiler 7 is connected to the smoke inlet of the bypass smoke outlet section 30, and the first smoke outlet of the bypass smoke outlet section 30 is connected to the smoke inlet of the smoke regulating valve 31. The smoke outlet of the smoke regulating valve 31 is connected to the first smoke inlet of the bypass smoke return section 32, the smoke outlet of the bypass smoke return section 32 is connected to the smoke inlet of the flexible connection 9, and the smoke outlet of the flexible connection 9 is connected to the smoke inlet of the chimney 10; the second smoke outlet of the bypass smoke outlet section 30 is connected to the lower smoke inlet of the smoke high-temperature spray section 34, the middle part of the smoke high-temperature spray section 34 is a heat exchange zone structure for smoke and high-temperature spray water, the smoke outlet of the smoke high-temperature spray section 34 is connected to the smoke inlet of the smoke low-temperature spray section 33, the middle part of the smoke low-temperature spray section 33 is a heat exchange zone structure for smoke and low-temperature spray water, and the smoke outlet of the smoke low-temperature spray section 33 is connected to the second smoke inlet of the bypass smoke return section 32;The waste hot water outlet of the flue gas high temperature spray section 34 is connected to the water inlet of the intermediate water pump 24, the water outlet of the intermediate water pump 24 is connected to the high temperature side water inlet of the intermediate water heat exchanger 23, the high temperature side water outlet of the intermediate water heat exchanger 23 is respectively connected to the high temperature spray water inlet of the flue gas high temperature spray section 34 and the spray water inlet of the full heat air preheater 26, the spray water outlet of the full heat air preheater 26 is connected to the low temperature spray water inlet of the flue gas low temperature spray section 33; the low temperature side water inlet of the intermediate water heat exchanger 23 is connected to the return water main pipe of the heat network return water H, and the low temperature side water outlet of the intermediate water heat exchanger 23 is connected to the water supply main pipe of the heat network supply water G. ;

[0008] The flue gas high temperature spraying section 34 is also provided with an alkali solution inlet, and the alkali solution inlet is connected to the alkali solution outlet of the alkali adding device 36 .

[0009] The full-heat air preheater 26, the flue gas low-temperature spray section 33, and the flue gas high-temperature spray section 34 can be arranged in an integrated manner or separately. The internal heat exchange zone is a countercurrent or cross-flow heat exchange structure composed of air and spray water arranged vertically or horizontally, in which a filler structure or an empty section structure is adopted inside.

[0010] The intermediate water heat exchanger 23 adopts a plate exchange structure.

[0011] The flue gas regulating valve 31 and the hot air regulating valve 28 both adopt an anti-corrosion and anti-condensation adjustable electric damper door structure with a high-efficiency flexible curved surface sealing structure on the wind side.

[0012] The main technical progress and innovations of the utility model include: first, a new mechanism of waste heat heating by a new combustion-steam combined cycle is realized, and the return water of the heat network is sent to the flue gas waste heat heat exchanger without a heat pump for preheating. The flue gas waste heat can be recovered to the maximum extent for heating without driving steam or electric energy, and the thermal efficiency of the whole plant is greatly improved; second, the most critical process flow of flue gas waste heat recovery is: the heat of the intermediate water in the low-temperature section of the flue gas is used to heat, humidify and superheat the intake air of the compressor in the full-heat air preheater, and then sent to the compressor and gas turbine for combustion and heat release to do work, and then enter the waste heat boiler to produce steam and do work. The flue gas carries a large amount of humidified water vapor and its latent heat of vaporization. , thereby increasing the flue gas enthalpy and its energy grade, and then increasing the intermediate water outlet temperature, which is beneficial to preheating the return water of the heat network; thirdly, the intermediate water replenishment adopts the flue gas condensate after adding alkali to neutralize, which has the effect of washing and cleaning the gas turbine intake air, avoiding the pollution and safety risks of particulate matter in the air; fourthly, the return water of the heat network recovers the waste heat of the flue gas for heating, which can expand the heating capacity and achieve the best energy utilization efficiency and its economic benefits; fifthly, the water vapor of the intake air humidification can be used as the main component of the high-energy gas driven by the gas turbine to do work, and can also reduce the oxygen content of the intake air, improve the combustion atmosphere in the combustion zone of the gas turbine, and reduce the generation of NOx The amount of flue gas is reduced, thereby reducing the content of major pollutants in flue gas, and therefore has important technical value for the operation and regulation of gas turbines and the entire combined cycle of combustion and steam. Sixth, the system thermal efficiency of the entire combined cycle of combustion and steam is increased by 10% to 15%, achieving a leapfrog technological advancement. Seventh, the operating energy consumption and operating costs of the flue gas waste heat recovery system are greatly reduced, and the operating economy of the entire combined cycle of combustion and steam cogeneration system is greatly improved. Eighth, condensate can be used for recycling and used for heating network water replenishment and as desalted water raw water, achieving water-saving benefits. Ninth, the overall emission concentration of flue gas pollutants is further reduced, and the substantial elimination of flue gas is achieved. Tenth, the combined cycle of combustion and steam As for the gas turbine power generation load and efficiency, although under full load operation, when the intake air temperature increases to, for example, 30-45°C, the gas turbine power generation load will decrease, but during winter heating operation, the gas turbine usually works at partial load, for example, it often runs in the load range of 50%-85%. At this time, when the intake air temperature increases, the gas turbine power generation load usually remains unchanged or increases slightly, and the compressor efficiency will be significantly improved (the maximum increase can reach 5%-6% or even higher), then the efficiency of the gas turbine + compressor overall unit will be significantly increased, so when the gas turbine load remains unchanged, its gas consumption will be reduced accordingly, so the thermal economy is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a system schematic diagram of the utility model.

[0014] Figure 1 The part numbers and names are as follows.

[0015] Grid-connected device 1, gas turbine generator 2, compressor 3, cold air inlet device 4, gas cabinet 5, gas turbine 6, waste heat boiler 7, waste heat boiler outlet section 8, flexible connection 9, chimney 10, steam turbine generator 11, steam turbine 12, condenser 14, feed water pump 16, cooling tower 17, intermediate water heat exchanger 23, intermediate water pump 24, fresh air inlet device 25, full heat air preheater 26, fresh air superheater 27, hot air regulating valve 28, bypass smoke outlet section 30, flue gas regulating valve 31, bypass smoke return section 32, flue gas low-temperature spray section 33, flue gas high-temperature spray section 34, flue gas waste heat spray tower 35, alkali adding device 36, ambient air A, humidification outlet air A1, heating outlet air A2, heating network water supply G, heating network return water H, high-temperature inlet water R1, and high-temperature outlet water R2. DETAILED DESCRIPTION

[0016] Figure 1 It is a system schematic diagram of the utility model.

[0017] The specific embodiments of the utility model are as follows: a steam-heated flue gas waste heat recovery and heating system of a combined combustion and steam cycle, comprising a conventional combined combustion and steam cycle power generation system and a flue gas waste heat recovery and heating system, wherein the conventional combined combustion and steam cycle power generation system comprises a grid-connected device 1, a gas turbine generator 2, a compressor 3, a cold air inlet device 4, a gas cabinet 5, a gas turbine 6, a waste heat boiler 7, a waste boiler outlet section 8, a flexible connection 9, a chimney 10, a steam turbine generator 11, a steam turbine 12, a condenser 14, a feed water pump 16, a cooling tower 17 and wind and smoke pipes, water vapor pipes and cables connected to each other, characterized in that the flue gas waste heat recovery and heating system comprises an intermediate water exchange Heater 23, intermediate water pump 24, fresh air inlet device 25, full hot air preheater 26, fresh air superheater 27, hot air regulating valve 28, bypass smoke outlet section 30, flue gas regulating valve 31, bypass smoke return section 32, flue gas waste heat spray tower 35, alkali adding device 36, wherein the flue gas waste heat spray tower 35 includes a flue gas low temperature spray section 33 and a flue gas high temperature spray section 34; wherein the lower lateral air inlet of the full hot air preheater 26 is connected to the fresh air inlet device 25, the air inlet of the fresh air inlet device 25 is communicated with the ambient air A, the middle part of the full hot air preheater 26 is a heat exchange zone structure for air and spray water, the air outlet of the full hot air preheater 26 is connected to the air inlet of the fresh air superheater 27, the fresh air The water inlet of the superheater 27 is connected to the high-temperature water inlet R1, the water outlet of the fresh air superheater 27 is connected to the high-temperature water outlet R2, and the air outlet of the fresh air superheater 27 is connected to the air inlet of the compressor 3 through the hot air regulating valve 28; the air inlet of the compressor 3 is also connected to the ambient air A through the cold air inlet device 4, the high-pressure exhaust port of the compressor 3 is connected to the air inlet of the gas turbine 6, the gas inlet of the gas turbine 6 is connected to the gas supply port of the gas cabinet 5, the smoke exhaust port of the gas turbine 6 is connected to the high-temperature smoke inlet of the waste heat boiler 7, the low-temperature smoke outlet of the waste heat boiler 7 is connected to the smoke inlet of the bypass smoke outlet section 30, and the first smoke outlet of the bypass smoke outlet section 30 is connected to the smoke inlet of the smoke regulating valve 31. The smoke outlet of the smoke regulating valve 31 is connected to the first smoke inlet of the bypass smoke return section 32, the smoke outlet of the bypass smoke return section 32 is connected to the smoke inlet of the flexible connection 9, and the smoke outlet of the flexible connection 9 is connected to the smoke inlet of the chimney 10; the second smoke outlet of the bypass smoke outlet section 30 is connected to the lower smoke inlet of the smoke high-temperature spray section 34, the middle part of the smoke high-temperature spray section 34 is a heat exchange zone structure for smoke and high-temperature spray water, the smoke outlet of the smoke high-temperature spray section 34 is connected to the smoke inlet of the smoke low-temperature spray section 33, the middle part of the smoke low-temperature spray section 33 is a heat exchange zone structure for smoke and low-temperature spray water, and the smoke outlet of the smoke low-temperature spray section 33 is connected to the second smoke inlet of the bypass smoke return section 32;The waste hot water outlet of the flue gas high temperature spray section 34 is connected to the water inlet of the intermediate water pump 24, the water outlet of the intermediate water pump 24 is connected to the high temperature side water inlet of the intermediate water heat exchanger 23, the high temperature side water outlet of the intermediate water heat exchanger 23 is respectively connected to the high temperature spray water inlet of the flue gas high temperature spray section 34 and the spray water inlet of the full heat air preheater 26, the spray water outlet of the full heat air preheater 26 is connected to the low temperature spray water inlet of the flue gas low temperature spray section 33; the low temperature side water inlet of the intermediate water heat exchanger 23 is connected to the return water main pipe of the heat network return water H, and the low temperature side water outlet of the intermediate water heat exchanger 23 is connected to the water supply main pipe of the heat network supply water G. ;

[0018] The flue gas high temperature spraying section 34 is also provided with an alkali solution inlet, and the alkali solution inlet is connected to the alkali solution outlet of the alkali adding device 36 .

[0019] The full-heat air preheater 26, the flue gas low-temperature spray section 33, and the flue gas high-temperature spray section 34 can be arranged in an integrated manner or separately. The internal heat exchange zone is a countercurrent or cross-flow heat exchange structure composed of air and spray water arranged vertically or horizontally, in which a filler structure or an empty section structure is adopted inside.

[0020] The intermediate water heat exchanger 23 adopts a plate exchange structure.

[0021] The flue gas regulating valve 31 and the hot air regulating valve 28 both adopt an anti-corrosion and anti-condensation adjustable electric damper door structure with a high-efficiency flexible curved surface sealing structure on the wind side.

[0022] It should be noted that the utility model proposes a new flue gas waste heat recovery method for a combined cycle of combustion and steam and a system process for heating the waste heat of heat network return water to expand the heating capacity. The above specific implementation method is only one of the implementation forms. Any other similar simple deformation implementation methods, such as using different heat exchange structures and their simple deformations; or simply adding or reducing equipment, or adjusting the order of equipment in the process; or performing deformation methods that ordinary professionals can think of, etc., or applying this technical method with the same or similar structure to different types of gas or oil, gas turbines or internal combustion engines with different structures, and other similar applications, all fall within the protection scope of the utility model.

Claims

1. A steam-heated flue gas waste heat recovery and heating system for a combined combustion and steam cycle, comprising a conventional combined combustion and steam cycle power generation system and a flue gas waste heat recovery and heating system, wherein the conventional combined combustion and steam cycle power generation system comprises a grid-connected device (1), a gas turbine generator (2), a compressor (3), a cold air inlet device (4), a gas cabinet (5), a gas turbine (6), a waste heat boiler (7), a waste heat boiler outlet section (8), a flexible connection (9), a chimney (10), a steam turbine generator (11), a steam turbine (12), a condenser (14), a feed water pump (16), a cooling tower (17) and wind and smoke ducts, water vapor ducts and cables connected thereto, characterized in that The flue gas waste heat recovery and heating system comprises an intermediate water heat exchanger (23), an intermediate water pump (24), a fresh air inlet device (25), a full-heat air preheater (26), a fresh air superheater (27), a hot air regulating valve (28), a bypass smoke outlet section (30), a flue gas regulating valve (31), a bypass smoke return section (32), a flue gas waste heat spray tower (35), and an alkali adding device (36), wherein the flue gas waste heat spray tower (35) comprises a flue gas low-temperature spray section (33) and a flue gas high-temperature spray section (34); wherein the lower lateral air inlet of the full-heat air preheater (26) is connected to the fresh air inlet device (25), the air inlet of the fresh air inlet device (25) is in communication with the ambient air (A), and the middle part of the full-heat air preheater (26) is an air inlet. The heat exchange zone structure of the air and the spray water is as follows: the air outlet of the full-heat air preheater (26) is connected to the air inlet of the fresh air superheater (27), the water inlet of the fresh air superheater (27) is connected to the high-temperature water inlet (R1), the water outlet of the fresh air superheater (27) is connected to the high-temperature water outlet (R2), and the air outlet of the fresh air superheater (27) is connected to the air inlet of the compressor (3) through the hot air regulating valve (28); the air inlet of the compressor (3) is also connected to the ambient air (A) through the cold air inlet device (4), the high-pressure exhaust port of the compressor (3) is connected to the air inlet of the gas turbine (6), the gas inlet of the gas turbine (6) is connected to the gas supply port of the gas cabinet (5), and the smoke outlet of the gas turbine (6) is connected to the high-temperature exhaust port of the waste heat boiler (7). The flue gas inlet is connected, the low-temperature flue gas outlet of the waste heat boiler (7) is connected to the smoke inlet of the bypass smoke outlet section (30), the first smoke outlet of the bypass smoke outlet section (30) is connected to the smoke inlet of the smoke regulating valve (31), the smoke outlet of the smoke regulating valve (31) is connected to the first smoke inlet of the bypass smoke return section (32), the smoke outlet of the bypass smoke return section (32) is connected to the smoke inlet of the flexible connection (9), and the smoke outlet of the flexible connection (9) is connected to the smoke inlet of the chimney (10); the second smoke outlet of the bypass smoke outlet section (30) is connected to the lower smoke inlet of the flue gas high-temperature spray section (34), the middle part of the flue gas high-temperature spray section (34) is a heat exchange zone structure for flue gas and high-temperature spray water, the smoke outlet of the flue gas high-temperature spray section (34) is connected to the smoke inlet of the flue gas low-temperature spray section (34), and the flue gas high-temperature spray section (34) is connected to the flue gas low-temperature spray section (34). The middle part of the flue gas low-temperature spray section (33) is a heat exchange zone structure for flue gas and low-temperature spray water, and the smoke outlet of the flue gas low-temperature spray section (33) is connected to the second smoke inlet of the bypass smoke return section (32); the waste hot water outlet of the flue gas high-temperature spray section (34) is connected to the water inlet of the intermediate water pump (24), the water outlet of the intermediate water pump (24) is connected to the high-temperature side water inlet of the intermediate water heat exchanger (23), the high-temperature side water outlet of the intermediate water heat exchanger (23) is respectively connected to the high-temperature spray water inlet of the flue gas high-temperature spray section (34) and the spray water inlet of the full-heat air preheater (26), and the spray water outlet of the full-heat air preheater (26) is connected to the low-temperature spray water inlet of the flue gas low-temperature spray section (33);The low-temperature side water inlet of the intermediate water heat exchanger (23) is connected to the return water main pipe of the heat network return water (H), and the low-temperature side water outlet of the intermediate water heat exchanger (23) is connected to the water supply main pipe of the heat network supply water (G). ; 2. The steam heat carrier type flue gas waste heat recovery and heating system of the combined cycle of combustion and steam as claimed in claim 1 is characterized in that The flue gas high temperature spray section (34) is also provided with an alkali solution inlet, and the alkali solution inlet is connected to the alkali solution outlet of the alkali adding device (36).

3. The steam heat carrier type flue gas waste heat recovery and heating system of the combustion-steam combined cycle according to claim 1 is characterized in that The full-heat air preheater (26), the flue gas low-temperature spray section (33), and the flue gas high-temperature spray section (34) can be arranged in an integrated manner or separately, and the internal heat exchange area is a countercurrent or cross-flow heat exchange structure composed of air and spray water arranged vertically or horizontally, wherein a filler structure or an empty section structure is used inside.

4. The steam heat carrier flue gas waste heat recovery and heating system of the combined combustion and steam cycle according to claim 1 is characterized in that The intermediate water heat exchanger (23) adopts a plate exchange structure.

5. The steam heat carrier type flue gas waste heat recovery and heating system of the combustion-steam combined cycle according to claim 1 is characterized in that The flue gas regulating valve (31) and the hot air regulating valve (28) both adopt an anti-corrosion and anti-condensation adjustable electric damper door structure with a high-efficiency flexible curved surface sealing structure on the wind side.

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