Desulfurization slurry flash evaporation injection pressurization air inlet humidification type flue gas waste heat recovery system

Abstract

The utility model discloses a desulfurization slurry flash evaporation injection pressurization air inlet humidification type flue gas waste heat recovery system, and belongs to the technical field of coal-fired boiler waste heat heat supply. According to the system, desulfurization slurry grading flash evaporation, injection pressurization and boiler inlet air heating and humidifying technologies are combined, flue gas deep waste heat recovery is achieved, desulfurization slurry is firstly fed into an injection flash evaporation tank to be subjected to negative pressure flash evaporation, flash steam is fed into a negative pressure ejector and is driven by heat supply steam to be pressurized into medium-pressure steam, and then heat supply network return water is heated; concentrated slurry is sent to a final-stage flash tank for final-stage negative pressure flash evaporation, flash evaporation steam heats intermediate water, and final-stage slurry is returned to a desulfurized water system; intermediate water is fed into a total heat air pre-heater to heat, humidify and overheat inlet air of the boiler and then is fed into the boiler, so that the content of water vapor in flue gas and the temperature of a desulfurization slurry outlet are increased; non-condensable gas with high SO2 content on the liquid level of final-stage condensed water is vacuumized by the ejector, so that the temperature of final-stage slurry is greatly reduced, the temperature of flue gas is greatly reduced, and the system is suitable for the scene that the temperature of return water of a heat supply network exceeds 50 DEG C.

Description

Technical Field

[0001] The utility model relates to a desulfurized slurry flash evaporation ejector pressurized air inlet humidifying type flue gas waste heat recovery system, belonging to the technical field of waste heat heating of coal-fired boilers. Background Technique

[0002] During the heat production process of boilers, a large amount of high-temperature flue gas is discharged. Recovering the waste heat of the flue gas can not only reduce the heat loss of the boiler, but also reduce the fuel consumption and pollutant emissions such as greenhouse gases, and improve the thermal efficiency of the boiler. The existing flue gas waste heat recovery systems mainly include three categories: (1) The first category is to use a shell-and-tube heat exchanger to realize the waste heat recovery of the flue gas, that is, to use a low-temperature economizer or an economizer, etc. An exchanger with a tubular structure or the like is installed on the outlet flue of the boiler to recover the waste heat of the flue gas and heat the boiler feed water or the heating return water. This method has a simple system and a relatively low total cost. The disadvantage is that the waste heat recovery rate is low, and it is affected by the changes in the inlet temperature of the heated water, the flue gas temperature, etc. Usually, the actual temperature difference is only about 20-30°C, which is about 1%-2% of the boiler heat output, and the latent heat of vaporization of the water vapor in the flue gas cannot be recovered. Therefore, deep heat recovery cannot be achieved. (2) The second category is to use the absorption heat pump flue gas deep recovery technology. The absorption heat pump is used to recover the waste heat of the flue gas and heat the network return water, etc. The flue gas temperature can be greatly reduced to about 30°C, and the waste heat recovery amount is equivalent to 8%-15% of the boiler heat output. Therefore, deep heat recovery can be achieved. However, the absorption heat pump needs to consume high-level heat sources such as steam to drive, and a large amount of acidic condensate will be generated in the flue gas, and an anti-corrosion heat exchanger needs to be used, and the equipment investment is relatively high. (3) The third category is the total heat exchange recovery technology based on air-flue gas. By humidifying the air, the dew point temperature of the flue gas is increased, and the condensation heat of the flue gas is recovered in the tail flue. This method has a simple system structure, does not require an additional driving heat source, and has a low investment cost. In recent years, the "steam-heat-carrying type boiler flue gas waste heat recovery" series of patented technologies jointly developed by Tsinghua University and Beijing Qingda Tiangong Energy Technology Research Institute (patent numbers CN104110675B, CN107166420A, CN206929794U, etc.) have been widely promoted and applied at present and have good application prospects. However, usually, the atmospheric pressure flue gas waste heat spray tower extracts heat from the flue gas by the intermediate water, and the size of the flue gas waste heat spray tower is very large, and a certain resistance will be increased on the flue gas side. If the outlet pressure margin of the original induced draft fan is insufficient, the fan needs to be replaced or a booster induced draft fan needs to be set up. The above situations will all cause an increase in cost, and sometimes the site does not have the implementation conditions.

[0003] In recent years, in the second type of flue gas waste heat recovery method, a method of using desulfurized slurry flash evaporation + absorption heat pump has emerged. That is, instead of using a flue gas waste heat exchanger, the heat in the flue gas is taken out from the desulfurized slurry through a flash tank, and the flash steam is sent to the heat pump for waste heat recovery, and the return water of the heat network or other process water is heated, while the concentrated liquid returns to the desulfurized circulating water. Its advantages are: there is no need to transform the flue gas system, reducing the on-site implementation difficulty; the quality of the condensate water is good, which is convenient for recycling. However, the disadvantages are also very obvious: the flue gas temperature can usually only be reduced to 42 - 45°C, recovering about half of the flue gas waste heat, which does not belong to deep heat recovery and can only be regarded as a half-finished project. There is still a large amount of flue gas waste heat escaping from the flue gas. In the future, secondary transformation is still needed to achieve deep heat recovery. The cost calculated for the unit waste heat recovery amount is relatively high, and the investment payback period is long. The fundamental reason why it cannot reduce the flue gas temperature to the 30°C level and achieve deep heat recovery is as follows: First, the desulfurized slurry flash evaporation complete set of equipment is a vacuum equipment, its system integration is relatively complex, the guarantee requirements are high, and the lower the flash steam temperature, the larger the specific volume, the larger the equipment volume, and the higher the cost; Second, a large amount of non-condensable gases such as SO2 will escape during the desulfurized slurry flash evaporation process. The flash steam is sent to the absorption heat pump, and it is difficult to evacuate during the condensation heat release process in the horizontal evaporator of the heat pump. The absolute pressure during actual operation can only be maintained at about 7 - 8 kPa. It is very difficult to further improve the vacuum degree with the existing equipment and conditions, and it is impossible to further improve the vacuum degree like a normal condenser. Therefore, the saturation temperature of the flash steam can only be reduced to the 38 - 40°C level, resulting in the flue gas temperature can only be reduced to the 40 - 45°C level; Third, this technical method still belongs to the heat pump method in essence, only the heat extraction device is different. It still requires a large amount of driving steam, with high operating costs, deteriorating the thermal power flexibility adjustment problem of the power plant, and even sometimes seriously affecting the technical and economic benefits of the power plant.

[0004] If the return water temperature of the heat network is too high, the outlet temperature of the return water of the heat network heated by the conventional desulfurized slurry flash evaporation + absorption heat pump method is affected by the operating characteristics of the heat pump and usually will not be too high. This results in a relatively limited heating amount for the return water of the heat network, which will limit the waste heat recovery efficiency. Utility Model Content

[0005] The purpose and task of the present utility model are to construct a brand-new integrated flue gas waste heat recovery system to achieve deep flue gas waste heat recovery in view of the respective inherent technical limitations of the above-mentioned various flue gas waste heat recovery systems and their impacts on the economy of the power plant.

[0006] The specific description of the present utility model is: A desulfurized slurry flash evaporation ejector pressurized air inlet humidifying flue gas waste heat recovery system, which consists of an original boiler and auxiliary machine subsystem, a desulfurized slurry staged flash evaporation and heating process water subsystem, and a combustion-supporting air heating and humidifying subsystem. The original boiler and auxiliary machine subsystem includes a boiler body 4, an air preheater 5, a forced draft fan 6, a dust collector 7, an induced draft fan 8, an original desulfurization tower 1, an original flue gas inlet pipe 2, and an original slurry pump 3. It is characterized in that the desulfurized slurry staged flash evaporation and heating process water subsystem includes an ejector flash evaporation tank 11, an ejector 15, an ejector heater 16, a vacuum pump 18, a final stage flash evaporation tank 31, an intermediate water heater 36, and connecting pipelines and components. The combustion-supporting air heating and humidifying subsystem includes a total heat air preheater 40, a fresh air superheater 41, an intermediate water pump 42, and connecting pipelines and components. Among them, the slurry inlet of the ejector flash evaporation tank 11 is connected to the waste heat slurry outlet of the bottom desulfurization slurry tank of the original desulfurization tower 1 through a waste heat slurry pump 10. The concentrated slurry outlet of the ejector flash evaporation tank 11 is connected to the slurry inlet of the final stage flash evaporation tank 31. The final stage concentrated slurry outlet of the final stage flash evaporation tank 31 is connected to the inlet of the original slurry pump 3. Inside the upper part of the ejector flash evaporation tank 11, there are a flash steam ejector demister 12 and an ejector washing spray layer 13. Its flash steam outlet is connected to the low-pressure steam inlet pipe 15b of the ejector 15. The high-pressure steam inlet pipe 15a of the ejector 15 is communicated with the steam supply pipe of the heating steam Q through an ejector regulating valve 14. The medium-pressure exhaust pipe 15c of the ejector 15 is connected to the steam inlet of the ejector heater 16. The condensate outlet of the ejector heater 16 is connected to the inlet of the ejector condensate pump 17. The outlet of the ejector condensate pump 17 is respectively connected to the inlets of the ejector washing spray layer 13 and the final stage washing spray layer 33, and is communicated with the outlet pipe of the ejector external discharged condensate W. The low-temperature water inlet of the ejector heater 16 is communicated with the incoming water pipe of the heat network return water H1, and is connected to the low-temperature water outlet of the ejector heater 16 through a valve. The low-temperature water outlet of the ejector heater 16 is communicated with the return water pipe of the heat network return water H2. Inside the upper part of the final stage flash evaporation tank 31, there are a flash steam final stage demister 32 and a final stage washing spray layer 33. Its flash steam outlet is connected to the steam inlet of the intermediate water heater 36 through a final stage connecting pipe 35. The condensate outlet of the intermediate water heater 36 is connected to the inlet of the intermediate water condensate pump 37. The outlet of the intermediate water condensate pump 37 is respectively connected to the low-temperature water outlet of the intermediate water heater 36, the spray water inlet of the total heat air preheater 40, and the outlet pipe of the intermediate external discharged condensate W2. The low-temperature water inlet of the intermediate water heater 36 is connected to the bottom water tank of the total heat air preheater 40 through an intermediate water pump 42. The outlet of the intermediate water non-condensable gas S2 of the intermediate water heater 36 is connected to the low-pressure steam inlet pipe 15b of the ejector 15. The outlet of the ejector non-condensable gas S1 of the ejector heater 16 is connected to the air inlet of the vacuum pump 18. The exhaust outlet of the vacuum pump 18 is communicated with the original flue gas inlet pipe 2 of the original desulfurization tower 1.An air inlet for ambient air A0 is provided at the lower part of the total heat air preheater 40, and an air outlet for humidified air A1 is provided at the top of the total heat air preheater 40. The air outlet for humidified air A1 is connected to the air inlet of the fresh air superheater 41. The air outlet of the fresh air superheater 41 is connected to the air inlet of the forced draft fan 6 through a connecting pipe for superheated air A2. The air outlet of the forced draft fan 6 communicates with the furnace of the boiler body 4 through the air inlet side of the air preheater 5; the flue gas side outlet of the air preheater 5 is connected to the original flue gas inlet pipe 2 through the dust collector 7 and the induced draft fan 8. The upstream of the original flue gas inlet pipe 2 is the inlet of the original flue gas Y1, and the downstream is the flue gas inlet of the original desulfurization tower 1. The top of the original desulfurization tower 1 is the outlet of the clean flue gas Y2; the circulating liquid outlet of the desulfurization slurry pool at the bottom of the original desulfurization tower 1 communicates with the inlet of the original slurry pump 3, the water inlet pipe of the desulfurization make-up water B, and the outlet of the final concentrated slurry of the final flash tank 31 respectively. The outlet of the original slurry pump 3 is connected to the circulating slurry inlet of the original desulfurization tower 1, and the blowdown port of the desulfurization slurry pool at the bottom of the original desulfurization tower 1 communicates with the drain pipe of the desulfurization wastewater P.;

[0007] The ejector heater 16 and the intermediate water heater 36 respectively adopt a vertical tubular heat exchange structure, with a condensate hot well provided at the bottom and a non-condensable gas discharge port provided above the liquid level of the hot well.

[0008] The ejector 15 adopts a high-efficiency wide-range negative pressure ejector structure with an internal flow cross-sectional area adjusted in an almost equal proportion.

[0009] The beneficial effects of the present utility model are as follows.

[0010] (1) Heat is taken from the desulfurization slurry without adding a flue gas waste heat exchanger and its flue gas resistance; at the same time, the waste heat in the low-temperature section of the flue gas enters the flue gas in the form of the latent heat of vaporization of water vapor through the way of humidifying the boiler inlet air through the final flash and the intermediate water system, increasing the water vapor content, energy grade and desulfurization slurry temperature of the flue gas. Thus, the return water of the heat network can be heated by the ejector heat pump composed of the ejector through flash evaporation, and the flue gas temperature can be reduced to the 30°C level, fundamentally avoiding the inherent disadvantages of the existing desulfurization slurry flash evaporation + absorption heat pump technology method, and the maximum waste heat recovery can reach more than 2 times.

[0011] (2) An ejector heat pump system is composed of equipment components such as the ejector flash tank 11, the ejector 15, and the ejector heater 16 to recover a part of the desulfurization slurry waste heat. The ejector 15 adopts a high-efficiency wide-range negative pressure ejector structure with an internal flow cross-sectional area adjusted in an almost equal proportion, so that the ejector heat pump can flexibly adapt to the changes in technical conditions such as the inlet and outlet temperatures, pressures, and flows on the desulfurization slurry flash evaporation side and the heat network return water heating side, and always maintain a very high system energy efficiency ratio.

[0012] (3) A large amount of SO2 and the like are contained in the non-condensable gas of the intermediate water heater 36. Instead of setting up a dedicated vacuum pump, it is directly extracted by the ejector 15, which can maintain a very high vacuum degree (reduced to the absolute pressure level of 2-4 kPa when necessary). Therefore, the last-stage flash tank 31 can achieve a very high vacuum degree, which is beneficial to significantly reducing the temperature of the desulfurization slurry, and then significantly reducing the flue gas temperature, realizing extremely deep flue gas waste heat recovery, and recovering the flue gas waste heat to the greatest extent.

[0013] (4) The steam side pressure of the ejector heater 16 is relatively high, so the technical requirements for the vacuum pump 18 for extracting non-condensable gas are reduced; at the same time, the ejector heater 16 and the intermediate water heater 36 respectively adopt a vertical tube-and-shell heat exchange structure, which is also beneficial to improving the extraction of non-condensable gas by the vacuum pump 18 and maintaining a higher vacuum degree.

[0014] (5) Using the condensate of the flash steam to wash the demister in each flash tank can maintain a higher demisting effect and replenish water to the desulfurization slurry to replace part or all of the original desulfurization water replenishment B. The latter's water replenishment source is often wastewater with a very high chloride ion content. After replacing it with the condensate of the flash steam, it can help significantly reduce the external discharge flow of the desulfurization wastewater P, and greatly reduce the secondary pollution and operation and maintenance costs caused by it, and improve the operation effect of the desulfurization system.

[0015] (6) This patent can be widely applied to the flue gas waste heat recovery and heating system of thermal power plants and boiler houses, promoting the realization of the comprehensive technical and economic benefits of energy conservation and environmental protection integration. Brief Description of the Drawings

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

[0017] Figure 1 The numbers and names of each component in it are as follows.

[0018] Original desulfurization tower 1, original flue gas inlet pipe 2, original slurry pump 3, boiler body 4, air preheater 5, forced draft fan 6, dust collector 7, induced draft fan 8, waste heat slurry pump 10, ejector flash tank 11, flash steam ejector demister 12, ejector washing spray layer 13, ejector regulating valve 14, ejector 15, high-pressure steam inlet pipe 15a, low-pressure steam inlet pipe 15b, medium-pressure exhaust pipe 15c, ejector heater 16, ejector condensate pump 17, vacuum pump 18, final flash tank 31, final flash steam demister 32, final washing spray layer 33, final connecting pipe 35, intermediate water heater 36, intermediate water condensate pump 37, total heat air preheater 40, fresh air superheater 41, intermediate water pump 42, ambient air A0, humidified air A1, superheated air A2, desulfurization make-up water B, return water from heat supply network H1, return water discharged from heat supply network H2, desulfurization wastewater P, heating steam Q, ejector non-condensable gas S1, intermediate water non-condensable gas S2, ejector externally discharged condensate W, intermediate water externally discharged condensate W2, original flue gas Y1, clean flue gas Y2. Specific implementation mode

[0019] Figure 1 It is a system schematic diagram and an embodiment of the present utility model.

[0020] The specific embodiments of the present utility model are as follows.

[0021] Specific description of an embodiment of the present utility model: A desulfurized slurry flash evaporation ejector pressurized air inlet humidifying flue gas waste heat recovery system is composed of an original boiler and auxiliary machine subsystem, a desulfurized slurry grading flash evaporation and heating process water subsystem, and a combustion-supporting air heating and humidifying subsystem. The original boiler and auxiliary machine subsystem includes a boiler body 4, an air preheater 5, a forced draft fan 6, a dust collector 7, an induced draft fan 8, an original desulfurization tower 1, an original flue gas inlet pipe 2, and an original slurry pump 3. It is characterized in that the desulfurized slurry grading flash evaporation and heating process water subsystem includes an ejector flash evaporation tank 11, an ejector 15, an ejector heater 16, a vacuum pump 18, a final stage flash evaporation tank 31, an intermediate water heater 36, and connecting pipelines and components. The combustion-supporting air heating and humidifying subsystem includes a total heat air preheater 40, a fresh air superheater 41, an intermediate water pump 42, and connecting pipelines and components. Among them, the slurry inlet of the ejector flash evaporation tank 11 is connected to the waste heat slurry outlet of the bottom desulfurization slurry pool of the original desulfurization tower 1 through a waste heat slurry pump 10. The concentrated slurry outlet of the ejector flash evaporation tank 11 is connected to the slurry inlet of the final stage flash evaporation tank 31. The final stage concentrated slurry outlet of the final stage flash evaporation tank 31 is connected to the inlet of the original slurry pump 3. Inside the upper part of the ejector flash evaporation tank 11, there is a flash steam ejector demister 12 and an ejector washing spray layer 13. Its flash steam outlet is connected to the low-pressure steam inlet pipe 15b of the ejector 15. The high-pressure steam inlet pipe 15a of the ejector 15 is communicated with the steam supply pipe of the heating steam Q through an ejector regulating valve 14. The medium-pressure exhaust pipe 15c of the ejector 15 is connected to the steam inlet of the ejector heater 16. The condensate outlet of the ejector heater 16 is connected to the inlet of the ejector condensate pump 17. The outlet of the ejector condensate pump 17 is respectively connected to the inlets of the ejector washing spray layer 13 and the final stage washing spray layer 33, and is communicated with the outlet pipe of the ejector external discharged condensate W. The low-temperature water inlet of the ejector heater 16 is communicated with the incoming water pipe of the heat network return water H1 and is connected to the low-temperature water outlet of the ejector heater 16 through a valve. The low-temperature water outlet of the ejector heater 16 is communicated with the return water pipe of the heat network return water H2. Inside the upper part of the final stage flash evaporation tank 31, there is a flash steam final stage demister 32 and a final stage washing spray layer 33. Its flash steam outlet is connected to the steam inlet of the intermediate water heater 36 through a final stage connecting pipe 35. The condensate outlet of the intermediate water heater 36 is connected to the inlet of the intermediate water condensate pump 37. The outlet of the intermediate water condensate pump 37 is respectively connected to the low-temperature water outlet of the intermediate water heater 36, the spray water inlet of the total heat air preheater 40, and the outlet pipe of the intermediate external discharged condensate W2. The low-temperature water inlet of the intermediate water heater 36 is connected to the bottom water tank of the total heat air preheater 40 through an intermediate water pump 42. The outlet of the intermediate water non-condensable gas S2 of the intermediate water heater 36 is connected to the low-pressure steam inlet pipe 15b of the ejector 15. The outlet of the ejector non-condensable gas S1 of the ejector heater 16 is connected to the air inlet of the vacuum pump 18. The exhaust outlet of the vacuum pump 18 is communicated with the original flue gas inlet pipe 2 of the original desulfurization tower 1.An air inlet for ambient air A0 is provided at the lower part of the total heat air preheater 40, and an air outlet for humidified air A1 is provided at the top of the total heat air preheater 40. The air outlet for humidified air A1 is connected to the air inlet of the fresh air superheater 41. The air outlet of the fresh air superheater 41 is connected to the air inlet of the forced draft fan 6 through a connecting pipe for superheated air A2. The air outlet of the forced draft fan 6 communicates with the furnace of the boiler body 4 through the air inlet side of the air preheater 5. The flue gas side outlet of the air preheater 5 is connected to the original flue gas inlet pipe 2 through the dust collector 7 and the induced draft fan 8. The upstream of the original flue gas inlet pipe 2 is the inlet of the original flue gas Y1, and the downstream is the flue gas inlet of the original desulfurization tower 1. The top of the original desulfurization tower 1 is the outlet of the clean flue gas Y2. The circulating liquid outlet of the desulfurization slurry pool at the bottom of the original desulfurization tower 1 communicates with the inlet of the original slurry pump 3, the water inlet pipe of the desulfurization make-up water B, and the outlet of the final-stage concentrated slurry of the final-stage flash tank 31 respectively. The outlet of the original slurry pump 3 is connected to the circulating slurry inlet of the original desulfurization tower 1. The blowdown port of the desulfurization slurry pool at the bottom of the original desulfurization tower 1 communicates with the drain pipe of the desulfurization wastewater P.;

[0022] The ejector heater 16 and the intermediate water heater 36 respectively adopt a vertical tube-type heat exchange structure, with a condensate hot well provided at the bottom and a non-condensable gas discharge port provided above the liquid level of the hot well.

[0023] The ejector 15 adopts a high-efficiency wide-range negative pressure ejector structure with an internal flow cross-sectional area adjusted in an approximately equal proportion.

[0024] It should be noted that the present utility model is based on key technologies such as multi-stage flash evaporation of desulfurization slurry, heating and humidifying of boiler inlet air, pressurized heat exchange of flash steam by an ejector heat pump, and vacuum extraction by an ejector, and proposes a complete set of new integrated systems and operation strategies for extremely deep flue gas waste heat recovery by flash evaporation of desulfurization slurry. According to this overall solution, there can be different specific implementation measures and specific implementation devices with different structures. The above specific implementation manners are only one of them. Any other similar simple deformed implementation manners, such as simple deformations of flash steam and heat exchangers and simple adjustments of pipelines, or simple changes in vacuum extraction methods and condensate recovery and utilization methods, etc., all fall within the protection scope of the present utility model.

Claims

1. A flue gas waste heat recovery system with flash evaporation, injection, pressurized air inlet and humidification of desulfurized slurry, which is composed of an original boiler and auxiliary subsystem, a desulfurized slurry graded flash evaporation and heating process water subsystem and a combustion air heating and humidification subsystem. The original boiler and auxiliary subsystem include a boiler body (4), an air preheater (5), a blower (6), a dust collector (7), an induced draft fan (8), an original desulfurization tower (1), an original flue gas inlet pipe (2) and an original slurry pump (3), characterized in that: The desulfurization slurry graded flash evaporation and heating process water subsystem comprises an ejector flash evaporator (11), an ejector (15), an ejector heater (16), a vacuum pump (18), a final flash evaporator (31), an intermediate water heater (36) and connecting pipelines and components; the combustion air heating and humidification subsystem comprises a full-heat air preheater (40), a fresh air superheater (41), an intermediate water pump (42) and connecting pipelines and components, wherein the slurry inlet of the ejector flash evaporator (11) is connected to the waste heat slurry outlet of the desulfurization slurry pool at the bottom of the original desulfurization tower (1) through a waste heat slurry pump (10), the concentrated slurry outlet of the ejector flash evaporator (11) is connected to the slurry inlet of the final flash evaporator (31), and the final flash evaporator (31) is connected to the slurry outlet of the final flash evaporator (31). The outlet of the final concentrated slurry of the tank (31) is connected to the inlet of the raw slurry pump (3); the upper part of the interior of the ejector flash tank (11) is provided with a flash steam ejector demister (12) and an ejector washing spray layer (13); the flash steam outlet is connected to the low-pressure steam inlet pipe (15b) of the ejector (15); the high-pressure steam inlet pipe (15a) of the ejector (15) is connected to the steam supply pipe of the heating steam (Q) via the ejector regulating valve (14); the medium-pressure exhaust pipe (15c) of the ejector (15) is connected to the steam inlet of the ejector heater (16); the condensate outlet of the ejector heater (16) is connected to the inlet of the ejector condensate pump (17); the outlets of the ejector condensate pump (17) are respectively connected to the ejector washing spray layer (13 ) is connected to the inlet of the final washing spray layer (33), and is communicated with the outlet pipe of the ejector condensate (W); the low-temperature water inlet of the ejector heater (16) is communicated with the water inlet pipe of the return water (H1) of the heating network, and is connected to the low-temperature water outlet of the ejector heater (16) through a valve, and the low-temperature water outlet of the ejector heater (16) is communicated with the return water pipe of the heating network (H2); the flash steam final demister (32) and the final washing spray layer (33) are arranged on the upper part of the interior of the final flash tank (31), and the flash steam outlet is connected to the steam inlet of the intermediate water heater (36) through the final connecting pipe (35), and the condensate outlet of the intermediate water heater (36) is connected to the intermediate water condensate pump (37) The inlet of the intermediate water condensate pump (37) is connected to the inlet of the intermediate water heater (36), the outlet of the intermediate water condensate pump (37) is respectively connected to the low-temperature water outlet of the intermediate water heater (36), the spray water inlet of the full-heat air preheater (40) and the outlet pipe of the intermediate external condensate water (W2); the low-temperature water inlet of the intermediate water heater (36) is connected to the tower bottom water pool of the full-heat air preheater (40) through the intermediate water pump (42); the outlet of the intermediate water non-condensable gas (S2) of the intermediate water heater (36) is connected to the low-pressure steam inlet pipe (15b) of the ejector (15); the outlet of the ejector non-condensable gas (S1) of the ejector heater (16) is connected to the air inlet of the vacuum pump (18), and the exhaust port of the vacuum pump (18) is connected to the original flue gas inlet pipe (2) of the original desulfurization tower (1);An air inlet for ambient air (A0) is provided at the bottom of the full-heat air preheater (40), and an air outlet for humidified air (A1) is provided at the top of the full-heat air preheater (40). The air outlet of the humidified air (A1) is connected to the air inlet of the fresh air superheater (41), and the air outlet of the fresh air superheater (41) is connected to the air inlet of the blower (6) through a connecting pipe for superheated air (A2). The air outlet of the blower (6) is connected to the furnace of the boiler body (4) through the air inlet side of the air preheater (5); the exhaust side outlet of the air preheater (5) is connected to the original flue gas inlet pipe (2) through a dust collector (7) and an induced draft fan (8). The original flue gas inlet pipe (2) is connected to the original flue gas (Y1), the upstream of the original flue gas inlet pipe (2) is the inlet of the original flue gas (Y1), the downstream is the inlet of the original desulfurization tower (1), and the top of the original desulfurization tower (1) is the outlet of the clean flue gas (Y2); the circulating liquid outlet of the desulfurization slurry pool at the bottom of the original desulfurization tower (1) is respectively connected to the inlet of the original slurry pump (3), the water inlet pipe of the desulfurization makeup water (B) and the final concentrated slurry outlet of the final flash tank (31), the outlet of the original slurry pump (3) is connected to the circulating slurry inlet of the original desulfurization tower (1), and the sewage outlet of the desulfurization slurry pool at the bottom of the original desulfurization tower (1) is connected to the drainage pipe of the desulfurization wastewater (P).

2. A desulfurization slurry flash evaporation injection pressurized air inlet humidification flue gas waste heat recovery system as claimed in claim 1, characterized in that The ejector heater (16) and the intermediate water heater (36) respectively adopt a vertical tube-in-tube heat exchange structure, a condensate water hot well is provided at the bottom, and a non-condensable gas discharge port is provided above the hot well liquid surface.

3. A desulfurization slurry flash injection pressurized air inlet humidification flue gas waste heat recovery system as claimed in claim 1, characterized in that The ejector (15) adopts a high-efficiency wide-range negative pressure ejector structure in which the internal flow cross-sectional area is adjusted in nearly equal proportion.

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