Combustion-steam combined cycle flue gas waste heat recovery heat supply system with total heat air pre-heater

Abstract

A combustion-steam combined cycle flue gas waste heat recovery heat supply system with a total heat air pre-heater belongs to the technical field of combustion-steam combined cycle and clean heat supply and comprises a conventional combustion-steam combined cycle power generation system and a heat supply system. Wherein the heat supply system comprises a condenser 14, a steam heater 15, a return water regulating valve 18, a flue gas heat exchange assembly 19, an intermediate water heat exchanger 23, an intermediate water pump 24, a fresh air inlet device 25, a total heat air pre-heater 26, a fresh air superheater 27, a hot air regulating valve 28 and an alkali adding device 36, and heat supply network return water heats intermediate water through the intermediate water heat exchanger 23; the medium water sprays, heats and humidifies the inlet air of the gas turbine in the total heat air pre-heater 26, and the inlet air is fed into the gas turbine; humidified steam improves the content of steam in smoke, the temperature of return water of a heat supply network is greatly improved in the smoke heat exchange assembly 19, and deep waste heat recovery is achieved. And heat supply network return water is supplied out after being heated by flue gas waste heat, dead steam waste heat and steam extraction of a steam turbine.

Description

Technical Field

[0001] The utility model relates to a combustion-steam combined cycle flue gas waste heat recovery heating system with a full-heat air preheater, belonging to the technical field of combustion-steam combined 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 cycle system of combustion and steam, expand heating capacity, improve thermal efficiency of the whole 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 and low-nitrogen combustion of flue gas.

[0007] The specific description of the utility model is: a conventional combustion-steam combined cycle power generation system and a heating system, wherein the conventional combustion-steam combined cycle power generation system includes 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, an air cooling island 13, a feed water pump 16 and wind and smoke pipes, water vapor pipes and cables connected to each other, characterized in that the heating system includes a condenser 14, a steam heater 15, a return water regulating valve 18, a flue gas heat exchange component 19, 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, and an alkali adding device 36, wherein the flue gas heat exchange component 19 includes a bypass flue gas valve 21 and a flue gas condenser 22; 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 communicated with the ambient air A, 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 communicated with the high-temperature water inlet R1, the water outlet of the fresh air superheater 27 is communicated with 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 air inlet of the compressor 3 through the cold air regulating valve 28. The air inlet device 4 is connected to the ambient air A, 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 smoke heat exchange component 19, the smoke outlet of the smoke condenser 22 in the smoke heat exchange component 19 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 spray water inlet of the full-heat air preheater 26 is connected to the low-temperature side outlet of the intermediate water heat exchanger 23, and the low-temperature side inlet of the intermediate water heat exchanger 23 is connected to the full-heat air preheater 26 through the intermediate water pump 24. The high temperature side inlet of the intermediate water heat exchanger 23 is connected to the inlet of the return water regulating valve 18 on the return water main pipe of the heat network return water H, the high temperature side outlet of the intermediate water heat exchanger 23 is connected to the water inlet of the flue gas condenser 22, the water outlet of the flue gas condenser 22 is connected to the outlet of the return water regulating valve 18, the condensate outlet of the flue gas condenser 22 is connected to the alkali outlet of the alkali adding device 36, and then connected to the make-up water inlet of the full heat air preheater 26, the outlet of the return water regulating valve 18 is also connected to the heat network return water inlet of the condenser 14, the heat network return water outlet of the condenser 14 is connected to the low temperature side inlet of the steam heater 15, and the low temperature side outlet of the steam heater 15 is connected to the water supply main pipe of the heat network supply water G;The steam inlet of the steam heater 15 is connected to the steam outlet of the steam turbine 12, the exhaust steam inlet of the condenser 14 is connected to the low-pressure exhaust port of the steam turbine 12 and the exhaust steam inlet of the air-cooling island 13, the condensate outlet of the condenser 14 is connected to the condensate outlet of the air-cooling island 13 and the condensate outlet of the steam heater 15, and is connected to the water inlet of the waste heat boiler 7 via the feed water pump 16.

[0008] The flue gas heat exchange component 19 also includes a flue gas recooler 20, wherein the smoke inlet of the flue gas recooler 20 is connected to the smoke outlet of the residual boiler outlet section 8, the smoke outlet of the flue gas recooler 20 is connected to the smoke inlet of the flue gas condenser 22, the water inlet of the flue gas recooler 20 is connected to the inlet of the return water regulating valve 18 on the return water mother pipe of the heat network return water H, and the water outlet of the flue gas recooler 20 is connected to the low temperature side inlet of the steam heater 15; the flue gas recooler 20 adopts a plate exchange structure or a fin tube bundle structure.

[0009] The full-heat air preheater 26 is a countercurrent heat exchange structure composed of air and spray water arranged vertically or horizontally, wherein a filler structure or an empty section structure is adopted inside.

[0010] An external structure or an internal structure is adopted between the intermediate water heat exchanger 23 and the full-heat air preheater 26. When the intermediate water heat exchanger 23 is external to the full-heat air preheater 26, a plate exchange structure is adopted. When the intermediate water heat exchanger 23 is internally mounted in the full-heat air preheater 26, a plate exchange structure or a tube bundle heat exchange structure is adopted.

[0011] The flue gas condenser 22 adopts a plate exchange structure or a fin tube bundle structure.

[0012] The bypass flue gas valve 21 is arranged in parallel with the flue gas condenser 22 . When the flue gas recooler 20 is arranged, the bypass flue gas valve 21 is arranged in parallel with the flue gas recooler 20 .

[0013] The bypass smoke valve 21 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.

[0014] The main technical progress and innovations of the utility model include: first, a new mechanism of waste heat heating in a new combustion-steam combined cycle is realized. The return water from the heating network is first sent to a flue gas waste heat heat exchanger without a heat pump for preheating, and then enters the turbine exhaust steam condenser for preheating, and then is sent to the steam heater for peak-shaving heating before being sent to heat users, thereby recovering the main waste heat of the combustion-steam combined cycle to the greatest extent and maximizing the thermal efficiency of the entire plant; second, the most critical process flow for flue gas waste heat recovery is: deep cooling of the return water from the heating network is adopted, and the intermediate water is heated by the return water from the heating network, rather than by the flue gas condensate (low temperature section) heating the intermediate water, and the intermediate water uses the heat of the return water from the heating network to heat, humidify and superheat the intake air of the compressor in the full hot air preheater, and then is sent to The compressor and gas turbine perform combustion, release heat and perform work, and then enter the waste heat boiler to produce steam and perform work. The flue gas carries a large amount of humidified water vapor to preheat the return water of the heat network before being discharged; thirdly, the intermediate water replenishment adopts the flue gas condensate after neutralization with alkali, 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 undergoes the following preheating process: first cooling and cooling, then restoring the original temperature through heat exchange with the flue gas heat exchanger, and then continuing to heat and substantially recover the waste heat of the flue gas, and at the same time recovering the waste heat of the turbine exhaust steam, so as to realize the main reliance on waste heat for heating. When necessary, the steam turbine extraction is used for peak-shaving heating, which can achieve the best energy cascade utilization efficiency and its economic benefits; fifthly, the intake air heating Wet water vapor can be used as the main component of 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, reduce the amount of NOx generated, and thus reduce the content of major pollutants in the flue gas. Therefore, it has important technical value for the operation and regulation of the gas turbine and the entire combined cycle of fuel and steam. Sixth, it can increase the system thermal efficiency of the entire combined cycle of fuel and steam to 100% to 117%, achieving a leap-forward technological progress. Seventh, it can greatly reduce the operating energy consumption and operating costs of the flue gas waste heat recovery system, and greatly improve the operating economy of the entire combined cycle of fuel and steam cogeneration system. Eighth, condensate can be used for recovery and used for water replenishment in the heating network and as desalted water raw water, achieving water-saving benefits. Ninth, it can further reduce the flue gas. The overall emission concentration of pollutants can achieve substantial whitening of flue gas; tenth, as far as the power generation load and efficiency of the gas turbine in the combined cycle of combustion and steam are concerned, although under full-load operation, when the intake air temperature increases to, for example, 30-45°C, the power generation load of the gas turbine 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 power generation load of the gas turbine 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 overall operation of the gas turbine + compressor 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

[0015] Figure 1 It is a system schematic diagram of the utility model.

[0016] Figure 1 The part numbers and names are as follows.

[0017] 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, air cooling island 13, condenser 14, steam heater 15, feed water pump 16, return water regulating valve 18, flue gas heat exchange component 19, flue gas recooler 20, bypass flue gas valve 21, flue gas condenser 22, 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, alkali adding device 36, ambient air A, humidification outlet air A1, heating outlet air A2, process make-up water B, heating network water supply G, heating network return water H, subcooling return water H1, preheating return water H2, high temperature return water H3, high temperature inlet water R1, high temperature outlet water R2. DETAILED DESCRIPTION

[0018] Figure 1 It is a system schematic diagram of the utility model.

[0019] The specific embodiments of the utility model are as follows: a conventional combustion-steam combined cycle power generation system and a heating system, wherein the conventional combustion-steam combined cycle power generation system includes 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, an air cooling island 13, a feed water pump 16 and wind and smoke pipes, water vapor pipes and cables connected to each other, characterized in that the heating system includes a condenser 14, a steam heater 15, a return water regulating valve 18, a flue gas heat exchange component 19, an intermediate water heat exchanger 23, an intermediate water pump 24, a fresh air inlet device 25, full-heat air preheater 26, fresh air superheater 27, hot air regulating valve 28, alkali adding device 36, wherein the flue gas heat exchange component 19 includes a bypass flue gas valve 21 and a flue gas condenser 22; 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 communicated with the ambient air A, 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 communicated with the high-temperature water inlet R1, the water outlet of the fresh air superheater 27 is communicated with 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 air inlet of the compressor 3 through the hot air regulating valve 28. The cold air inlet device 4 is connected to the ambient air A, 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 smoke heat exchange component 19, the smoke outlet of the smoke condenser 22 in the smoke heat exchange component 19 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 spray water inlet of the full heat air preheater 26 is connected to the low-temperature side outlet of the intermediate water heat exchanger 23, and the low-temperature side inlet of the intermediate water heat exchanger 23 is connected to the full heat air preheater 2 through the intermediate water pump 24. 6, the high temperature side inlet of the intermediate water heat exchanger 23 is connected to the inlet of the return water regulating valve 18 on the return water mother pipe of the heat network return water H, the high temperature side outlet of the intermediate water heat exchanger 23 is connected to the water inlet of the flue gas condenser 22, the water outlet of the flue gas condenser 22 is connected to the outlet of the return water regulating valve 18, the condensate outlet of the flue gas condenser 22 is connected to the alkali outlet of the alkali adding device 36, and then connected to the make-up water inlet of the full heat air preheater 26, the outlet of the return water regulating valve 18 is also connected to the heat network return water inlet of the condenser 14, the heat network return water outlet of the condenser 14 is connected to the low temperature side inlet of the steam heater 15, and the low temperature side outlet of the steam heater 15 is connected to the water supply mother pipe of the heat network supply water G;The steam inlet of the steam heater 15 is connected to the steam outlet of the steam turbine 12, the exhaust steam inlet of the condenser 14 is connected to the low-pressure exhaust port of the steam turbine 12 and the exhaust steam inlet of the air-cooling island 13, the condensate outlet of the condenser 14 is connected to the condensate outlet of the air-cooling island 13 and the condensate outlet of the steam heater 15, and is connected to the water inlet of the waste heat boiler 7 via the feed water pump 16.

[0020] The flue gas heat exchange component 19 also includes a flue gas recooler 20, wherein the smoke inlet of the flue gas recooler 20 is connected to the smoke outlet of the residual boiler outlet section 8, the smoke outlet of the flue gas recooler 20 is connected to the smoke inlet of the flue gas condenser 22, the water inlet of the flue gas recooler 20 is connected to the inlet of the return water regulating valve 18 on the return water mother pipe of the heat network return water H, and the water outlet of the flue gas recooler 20 is connected to the low temperature side inlet of the steam heater 15; the flue gas recooler 20 adopts a plate exchange structure or a fin tube bundle structure.

[0021] The full-heat air preheater 26 is a countercurrent heat exchange structure composed of air and spray water arranged vertically or horizontally, wherein a filler structure or an empty section structure is adopted inside.

[0022] An external structure or an internal structure is adopted between the intermediate water heat exchanger 23 and the full-heat air preheater 26. When the intermediate water heat exchanger 23 is external to the full-heat air preheater 26, a plate exchange structure is adopted. When the intermediate water heat exchanger 23 is internally mounted in the full-heat air preheater 26, a plate exchange structure or a tube bundle heat exchange structure is adopted.

[0023] The flue gas condenser 22 adopts a plate exchange structure or a fin tube bundle structure.

[0024] The bypass flue gas valve 21 is arranged in parallel with the flue gas condenser 22 . When the flue gas recooler 20 is arranged, the bypass flue gas valve 21 is arranged in parallel with the flue gas recooler 20 .

[0025] The bypass smoke valve 21 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.

[0026] 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 waste heat with heat network return water to expand 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 water replenishment methods; 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 combined cycle flue gas waste heat recovery and heating system with a full-heat air preheater, comprising a conventional combined cycle power generation system and a heating system, wherein the conventional combined 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), an air cooling island (13), a feed water pump (16), and wind and smoke ducts, water and steam ducts and cables connected thereto, characterized in that The heating system comprises a condenser (14), a steam heater (15), a return water regulating valve (18), a flue gas heat exchange component (19), 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), and an alkali adding device (36), wherein the flue gas heat exchange component (19) comprises a bypass flue gas valve (21) and a flue gas condenser (22); 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 communicated with the ambient air (A), and the full-heat air preheater (26) is connected to the fresh air inlet device (25), and the fresh air inlet device (25) is communicated with the ambient air (A). The air outlet of the fresh air superheater (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) via the hot air regulating valve (28); the air inlet of the compressor (3) is also connected to the ambient air (A) via 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 exhaust port of the gas turbine (6) is connected to the waste heat boiler ( The high-temperature flue gas inlet of the waste heat boiler (7) is connected to the high-temperature flue gas inlet of the flue gas heat exchange component (19), the low-temperature flue gas outlet of the waste heat boiler (7) is connected to the smoke inlet of the flue gas heat exchange component (19), the smoke outlet of the flue gas condenser (22) in the flue gas heat exchange component (19) 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 spray water inlet of the full-heat air preheater (26) is connected to the low-temperature side outlet of the intermediate water heat exchanger (23), the low-temperature side inlet of the intermediate water heat exchanger (23) is connected to the spray water outlet of the full-heat air preheater (26) through the intermediate water pump (24), and the high-temperature side inlet of the intermediate water heat exchanger (23) is connected to the return water on the return water main pipe of the heat network return water (H). The inlet of the water regulating valve (18) is connected, the high temperature side outlet of the intermediate water heat exchanger (23) is connected to the water inlet of the flue gas condenser (22), the water outlet of the flue gas condenser (22) is connected to the outlet of the return water regulating valve (18), the condensate outlet of the flue gas condenser (22) is connected to the alkali liquid outlet of the alkali adding device (36), and then connected to the make-up water inlet of the full heat air preheater (26), the outlet of the return water regulating valve (18) is also connected to the heat network return water inlet of the condenser (14), the heat network return water outlet of the condenser (14) is connected to the low temperature side inlet of the steam heater (15), and the low temperature side outlet of the steam heater (15) is connected to the water supply main pipe of the heat network water supply (G);The steam inlet of the steam heater (15) is connected to the steam outlet of the steam turbine (12), the exhaust steam inlet of the condenser (14) is connected to the low-pressure exhaust port of the steam turbine (12) and to the exhaust steam inlet of the air cooling island (13), the condensate outlet of the condenser (14) is connected to the condensate outlet of the air cooling island (13) and the condensate outlet of the steam heater (15), and is connected to the water inlet of the waste heat boiler (7) via the feed water pump (16).

2. The combustion-steam combined cycle flue gas waste heat recovery heating system with full-heat air preheater according to claim 1 is characterized in that The flue gas heat exchange component (19) further comprises a flue gas recooler (20), wherein a smoke inlet of the flue gas recooler (20) is connected to a smoke outlet of a residual boiler outlet section (8), a smoke outlet of the flue gas recooler (20) is connected to a smoke inlet of a flue gas condenser (22), a water inlet of the flue gas recooler (20) is connected to an inlet of a return water regulating valve (18) on a return water main pipe of a heat network return water (H), and a water outlet of the flue gas recooler (20) is connected to a low temperature side inlet of a steam heater (15); the flue gas recooler (20) adopts a plate exchange structure or a fin tube bundle structure.

3. The combustion-steam combined cycle flue gas waste heat recovery heating system with full-heat air preheater as claimed in claim 1, characterized in that The full-heat air preheater (26) is a countercurrent heat exchange structure composed of air and spray water arranged vertically or horizontally, wherein a filler structure or an empty section structure is adopted inside.

4. The combustion-steam combined cycle flue gas waste heat recovery heating system with full-heat air preheater as claimed in claim 1, characterized in that The intermediate water heat exchanger (23) and the full-heat air preheater (26) are connected by an external structure or a built-in structure. When the intermediate water heat exchanger (23) is external to the full-heat air preheater (26), a plate heat exchange structure is adopted. When the intermediate water heat exchanger (23) is built into the full-heat air preheater (26), a plate heat exchange structure or a tube bundle heat exchange structure is adopted.

5. The combustion-steam combined cycle flue gas waste heat recovery heating system with full-heat air preheater as claimed in claim 1, characterized in that The flue gas condenser (22) adopts a plate exchange structure or a fin tube bundle structure.

6. The combustion-steam combined cycle flue gas waste heat recovery heating system with full-heat air preheater as claimed in claim 1, characterized in that The bypass flue gas valve (21) is arranged in parallel with the flue gas condenser (22); when a flue gas recooler (20) is provided, the bypass flue gas valve (21) is arranged in parallel with the flue gas recooler (20).

7. The combustion-steam combined cycle flue gas waste heat recovery heating system with full-heat air preheater as claimed in claim 1, characterized in that The bypass smoke valve (21) and the hot air regulating valve (28) both adopt an anti-corrosion and anti-condensation adjustable electric damper door structure with an air-side high-efficiency flexible curved surface sealing structure.

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