A boiler flue gas heat comprehensive utilization white smoke removal device and method

Abstract

The application discloses a boiler flue gas heat comprehensive utilization white smoke removing device and method, belongs to the boiler and white smoke removing technical field, including white smoke removing system, white smoke removing system and refrigeration system, air cooling system and reheating system are connected, white smoke removing system includes boiler device, boiler device and air preheater intercommunication, air preheater and bag-type dust collector intercommunication, bag-type dust collector and induced draft fan intercommunication, induced draft fan and desulfurizing tower intercommunication, desulfurizing tower and chimney intercommunication.The application adopts the above-mentioned boiler flue gas heat comprehensive utilization white smoke removing device and method, through air cooling and cold water cooling two ways, the water vapor in flue gas is condensed down;firstly, the flue gas after desulfurizing tower is warmed by circulating water backwater, then the boiler blowdown water with higher temperature is used;the hot air after secondary warming by air condenser and air preheater is sent into the air supply fan inlet, which can improve the air supply fan inlet air temperature.

Description

Technical Field

[0001] This invention relates to the field of boiler and flue gas desulfurization technology, and in particular to a desulfurization device and method for comprehensive utilization of boiler flue gas heat. Background Technology

[0002] Coal-fired boilers are generally equipped with flue gas desulfurization devices. After the flue gas is treated, it is vented to the chimney. Wet flue gas desulfurization is a widely used desulfurization process. The clean flue gas emitted after wet desulfurization is generally in a saturated state. The state of the flue gas changes from high temperature and low humidity to low temperature and high humidity. During this process, the sensible heat of the flue gas cooling is converted into the latent heat of water vapor in the flue gas. When the flue gas with high humidity is emitted into the environment, the water vapor in the flue gas is easy to condense and produce "white smoke". It will also carry soluble salts and other substances in the flue gas into the atmosphere, which seriously affects the environmental quality. Based on the mechanism of wet plume formation and dissipation, to eliminate wet plume, it is necessary to change the initial state point of the wet flue gas when it is discharged from the chimney, and to keep the wet flue gas in an unsaturated state as much as possible during the diffusion process in the ambient air. One way to solve this problem is to install a flue gas heating device at the end of the chimney. After heating the flue gas, although the flue gas can be transformed into an unsaturated state, the actual water vapor in the flue gas is not reduced. Phase change condensation + MGGH flue gas reheat technology can also be used. Phase change condensers generally use circulating water to cool the flue gas to achieve the purpose of condensation and dehydration, but the effect is often not ideal. The MGGH system uses hot water as a heat transfer medium to transfer the heat of the flue gas before the desulfurization tower to the flue gas after the desulfurization tower, but the flue gas temperature is too low, which is not conducive to the operation of the desulfurization device. At the same time, the heat of the flue gas is not effectively utilized, making the operation uneconomical.

[0003] The primary air fan and forced draft fan of the boiler draw air directly from the atmosphere. The temperature of the inlet air will change with the ambient temperature. Especially when the ambient temperature drops in winter, the boiler operating conditions will deteriorate. A large amount of cold air will directly enter the coal mill and air preheater. The lower inlet air temperature of the air preheater will aggravate the blockage of the air preheater and reduce the overall operating efficiency of the boiler.

[0004] The periodic and continuous blowdowns of the boiler unit are collected in the blowdown expansion tank and then transported to the boiler circulating water for reuse by the recycling water pump. The temperature of the blowdowns is generally high, and their direct entry into the circulating water system is equivalent to increasing the cooling load of the circulating water. Summary of the Invention

[0005] The purpose of this invention is to provide a de-whitening device and method for comprehensive utilization of boiler flue gas heat. By using both air cooling and cold water cooling, water vapor in the flue gas is condensed. After the water vapor condenses and precipitates, it is then captured by a demister, significantly reducing the moisture content of the flue gas and thus reducing and eliminating the "white smoke" problem. This reduces pollutant emissions and efficiently recovers and utilizes condensate from the flue gas. Furthermore, air cooling alone is sufficient in winter, achieving both energy saving and white smoke removal. First, the flue gas after the desulfurization tower is heated by circulating water return, and then the flue gas temperature is further increased by passing it through the higher-temperature boiler wastewater. This reduces the load on the circulating water cooling tower and, with the increased flue gas temperature, enhances the white smoke removal effect and slows down corrosion in the flue. The hot air, after being heated twice by the air condenser and air preheater, is then sent to the inlet of the blower, increasing the blower inlet air temperature and raising the wall temperature of the boiler air preheater heat exchange tubes. This temperature increase particularly improves the boiler's winter operating conditions, reduces air preheater blockage, and enhances the boiler's economic efficiency.

[0006] To achieve the above objectives, the present invention provides a desulfurization device for comprehensive utilization of boiler flue gas heat, comprising a desulfurization system connected to a refrigeration system, an air-cooling system and a reheat system. The desulfurization system includes a boiler unit connected to an air preheater, which is connected to a bag filter, which is connected to an induced draft fan, which is connected to a desulfurization tower, which is connected to a chimney.

[0007] Preferably, the refrigeration system includes a refrigeration unit, which is connected to a chilled water circulating pump and a hot water cooler, respectively. The chilled water circulating pump is connected to a chilled water condenser, the chilled water condenser is connected to the refrigeration unit, the hot water cooler is connected to a hot water tank, the hot water tank is connected to a hot water circulating pump, and the hot water circulating pump is connected to the refrigeration unit.

[0008] Preferably, the air-cooled system includes a blower, the blower is connected to an air condenser, the air condenser is connected to an air cooler, the air cooler is connected to a blower, and the blower is connected to an air preheater.

[0009] Preferably, the reheat system includes a circulating water reheater and a wastewater reheater, wherein the circulating water reheater is connected to the chiller unit and the circulating water device respectively, and the wastewater reheater is connected to the boiler unit and the circulating water device respectively.

[0010] Preferably, the heat transfer water cooler and the air cooler are installed between the induced draft fan and the desulfurization tower according to the direction of boiler flue gas flow. The heat transfer water cooler is connected to both the induced draft fan and the air cooler, and the air cooler is connected to the desulfurization tower.

[0011] Preferably, the desulfurization tower is equipped with a concentration section, an absorption section, and a water washing section. The concentration section is located at the bottom of the desulfurization tower, and the absorption section is located between the concentration section and the water washing section. The desulfurization tower above the water washing section is equipped with a ridge demister, an air condenser, a cold water condenser, and a wire mesh demister. The air condenser and the cold water condenser are located between the ridge demister and the wire mesh demister, the cold water condenser is located above the air condenser, and the wire mesh demister is located above the cold water condenser.

[0012] Preferably, the circulating water reheater and the wastewater reheater are installed between the desulfurization tower and the chimney in the direction of boiler flue gas flow. The circulating water reheater is connected to the desulfurization tower and the wastewater reheater respectively, and the wastewater reheater is connected to the chimney.

[0013] Preferably, the boiler unit is connected to the hot water tank, the desulfurization tower is connected to the water circulation tank, and the air cooler is equipped with an air cooler branch line.

[0014] This invention provides a method for removing whitening gas by comprehensively utilizing the heat of boiler flue gas. The method, using the aforementioned device for removing whitening gas by comprehensively utilizing the heat of boiler flue gas, specifically includes the following steps: S1. The hot flue gas from the boiler unit passes through the air preheater and the bag filter in sequence before being drawn into the induced draft fan. The flue gas after the induced draft fan first passes through the hot water cooler, then through the air cooler, and is then sent to the desulfurization tower. S2. The heat transfer water from the refrigeration unit is heated by flue gas and then enters the hot water tank. It is then sent back to the generator of the refrigeration unit for circulation by the heat transfer water circulation pump. S3. After entering the desulfurization tower, the flue gas passes through the concentration section, absorption section, water washing section, and ridge demister, and then enters the air condenser and cold water condenser. The blower sends the air to the air condenser to pre-cool the flue gas, and then the heated air is sent to the air cooler at the inlet of the desulfurization tower for heat exchange. S4. After being further heated, the air is sent to the boiler blower inlet and then enters the boiler unit. The cold water pumped by the cold water circulation pump further cools the flue gas in the cold water condenser and then returns to the refrigeration unit. The condensed liquid flows into the water circulation tank and is used as makeup water for the desulfurization tower. S5. After passing through the wire mesh demister, the flue gas is sent out of the desulfurization tower. The flue gas exiting the desulfurization tower first passes through the circulating water reheater. The circulating water with a higher temperature from the refrigeration unit heats the flue gas in the circulating water reheater. The cooled circulating water returns to the circulating water device and then passes through the boiler wastewater reheater. The boiler wastewater with a higher temperature further heats the flue gas in the wastewater reheater. The cooled boiler wastewater is sent to the circulating water device as makeup water and finally sent to the chimney for venting.

[0015] Therefore, the present invention employs the above-mentioned desulfurization device and method for comprehensive utilization of boiler flue gas heat, which has the following beneficial effects: 1) By using both air cooling and cold water cooling, the water vapor in the flue gas is condensed. After the water vapor in the flue gas condenses and precipitates, it is then captured by a demister, which greatly reduces the moisture content of the flue gas, thereby reducing and eliminating the "white smoke" problem. On the one hand, it reduces the emission of pollutants and the condensate in the flue gas is efficiently recycled. On the other hand, only air cooling is needed in winter, which takes into account both energy saving and white smoke removal. 2) First, the flue gas after the desulfurization tower is heated by circulating water return water, and then the wastewater is discharged through the boiler at a higher temperature to further increase the flue gas temperature. On the one hand, this can reduce the load on the circulating water cooling tower, and on the other hand, the desulfurization effect will be more obvious after the flue gas temperature of the chimney is increased, and the corrosion in the flue can also be slowed down. 3) The hot air, which has been heated twice by the air condenser and air preheater, is sent to the inlet of the blower. This can increase the inlet air temperature of the blower and the wall temperature of the heat exchange tubes of the boiler air preheater. Increasing the air temperature can especially improve the operating conditions of the boiler in winter, reduce the blockage rate of the air preheater, and improve the economic efficiency of boiler operation.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is a flowchart of a method for de-whitening through comprehensive utilization of boiler flue gas heat according to the present invention.

[0018] Figure Labels 1. Baghouse dust collector; 2. Air preheater; 3. Blower; 4. Sewage discharge pipeline; 5. Circulating water reheater; 6. Wastewater reheater; 7. Cold water condenser; 8. Air condenser; 9. Blower; 10. Cold water circulating pump; 11. Refrigeration unit; 12. Desulfurization tower; 13. Air cooler; 14. Heat medium water cooler; 15. Exhaust fan; 16. Heat medium water circulating pump; 17. Air cooler bypass line. Detailed Implementation

[0019] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0021] Example 1 This invention provides a desulfurization device for comprehensive utilization of boiler flue gas heat, including a desulfurization system connected to a refrigeration system, an air-cooling system, and a reheat system. The desulfurization system includes a boiler unit connected to an air preheater 2. The air preheater 2 utilizes the waste heat of the high-temperature flue gas from the boiler to heat the combustion air, improving boiler combustion efficiency, reducing the initial flue gas temperature, and cooling and reducing the load on subsequent equipment. The hot air, after being heated twice by the air condenser 8 and the air preheater 2, is sent to the inlet of the blower 3, which can increase the inlet air temperature of the blower 3 and the wall temperature of the heat exchange tubes in the air preheater inside the boiler. After the air temperature is increased, the boiler's operating conditions in winter are particularly improved, the air preheater blockage rate is reduced, and the economic efficiency of boiler operation is improved. The air preheater 2 is connected to a bag filter 1, which filters dust particles in the flue gas, achieving preliminary purification of the flue gas and preventing dust from abrading subsequent heat exchange equipment and clogging the packing of the desulfurization tower 12. The bag filter 1 is connected to the induced draft fan 15, which is connected to the desulfurization tower 12. The desulfurization tower 12 is connected to the chimney and the water circulation tank. The induced draft fan 15 overcomes the system resistance and drives the flue gas to pass sequentially through the heat transfer medium water cooler 14, the air cooler 13, the desulfurization tower 12, the circulating water reheater 5, and the wastewater reheater 6, and finally exits from the chimney.

[0022] The desulfurization tower 12 is internally equipped with a concentration section, an absorption section, and a washing section. The concentration section is located at the bottom of the tower, and the absorption section is located between the concentration section and the washing section. The concentration section is the bottom high-concentration slurry contact zone, where high-temperature flue gas evaporates the water in the slurry to achieve slurry concentration and simultaneously cools the flue gas. The absorption section is the core desulfurization zone, where acidic pollutants such as SO2 and SO3 are removed from the flue gas through countercurrent contact of the desulfurization slurry. The washing section washes away slurry droplets and residual pollutants entrained in the flue gas and further cools it. Above the washing section, the desulfurization tower 12 is equipped with a ridge demister, an air condenser 8, a cold water condenser 7, and a wire mesh demister. The air condenser 8 and the cold water condenser 7 are located between the ridge demister and the wire mesh demister, with the cold water condenser 7 above the air condenser 8 and the wire mesh demister above the cold water condenser 7. The ridge demister initially removes large-diameter droplets entrained in the flue gas to prevent scaling and corrosion of subsequent equipment. The wire mesh demister precisely removes tiny droplets and condensate remaining in the flue gas, ensuring that the flue gas entering the reheat system is dry and free of droplets, thus preventing droplets from corroding the reheater or being carried into the chimney.

[0023] The refrigeration system includes a refrigeration unit 11, which produces low-temperature chilled water to provide refrigerant for the heat transfer medium water cooler 14 and the chilled water condenser 7, achieving deep cooling and dehumidification of the flue gas. Simultaneously, the generated condensation heat can be recovered through a circulating water system for use in the reheat system. The refrigeration unit 11 is connected to both the chilled water circulation pump 10 and the heat transfer medium water cooler 14. The chilled water circulation pump 10 is connected to the chilled water condenser 7, and the chilled water condenser 7 is connected to the refrigeration unit 11. The chilled water circulation pump 10 provides circulation power for the low-temperature chilled water produced by the refrigeration unit 11, delivering the chilled water to the chilled water condenser 7. After heat exchange with the flue gas in the desulfurization tower 12, the water flows back to the refrigeration unit 11, achieving a closed-loop cycle and ensuring a stable supply of cold water. The chilled water condenser 7 is the final deep dehumidification and heat exchange component for the flue gas in the desulfurization tower 12. Utilizing the low-temperature chilled water provided by the refrigeration unit 11, it lowers the flue gas temperature below the dew point, causing most of the water vapor to condense and precipitate, which is crucial for ensuring effective desulfurization.

[0024] The heat transfer water cooler 14 is connected to the hot water tank, which is connected to the heat transfer water circulation pump 16, which is connected to the refrigeration unit 11. The heat transfer water cooler 14 uses the chilled water from the refrigeration system as the refrigerant to perform a first deep cooling of the medium-temperature flue gas at the outlet of the induced draft fan 15, causing partial condensation of water vapor in the flue gas, recovering the condensate, and reducing the moisture content of the flue gas. Simultaneously, it provides heat exchange conditions on the heat source side for the refrigeration system. The hot water tank stores the hot water recovered by the heat transfer water cooler 14 and the boiler unit, providing a stable driving heat source for the refrigeration unit 11, while also buffering heat to ensure continuous and stable operation of the refrigeration unit 11. The heat transfer water circulation pump 16 provides circulation power for the heat transfer water in the hot water tank, transporting the hot water to the refrigeration unit 11. After heat exchange, the hot water flows back to the hot water tank, achieving a closed-loop circulation and ensuring a stable heat source supply for the refrigeration unit 11. The boiler unit is connected to the hot water tank, and another route of boiler wastewater is sent to the hot water tank via the drain pipe 4 as makeup water for the heat transfer water circulation system.

[0025] The heat transfer water cooler 14 and the air cooler 13 are installed between the induced draft fan 15 and the desulfurization tower 12 according to the direction of boiler flue gas flow. The heat transfer water cooler 14 is connected to the induced draft fan 15 and the air cooler 13 respectively, and the air cooler 13 is connected to the desulfurization tower 12.

[0026] The air-cooling system includes a blower 9, which provides cold air power to the entire system, delivering ambient air to various heat exchange devices as a refrigerant for cooling and dehumidification. The blower 9 is connected to an air condenser 8, which uses cold air to deeply cool and dehumidify the desulfurized wet flue gas, serving as a pre-treatment stage for the refrigeration system's condenser and reducing the refrigeration system load. The air condenser 8 is connected to an air cooler 13, transferring the absorbed heat to the flue gas side for energy recovery. The air cooler 13 is connected to a blower 3, which has a bypass line 17. The blower 3 is also connected to an air preheater 2. The air cooler 13 uses cold air to pre-cool and dehumidify the flue gas, reducing the moisture content of the flue gas entering the desulfurization tower 12, reducing the condensation load within the tower. The air, after absorbing heat from the flue gas, is delivered by the blower 3 to the air preheater 2, where it is heated and used as boiler combustion air, achieving heat recovery and utilization. The blower 3 delivers the air that has absorbed heat in the air cooler 13 to the air preheater 2, where it is further heated and then sent to the boiler unit as combustion air to improve the boiler's combustion efficiency and achieve energy cascade utilization.

[0027] The reheat system includes a circulating water reheater 5 and a wastewater reheater 6. The circulating water reheater 5 is connected to both the refrigeration unit 11 and the circulating water system. The high-temperature circulating water from the refrigeration unit 11 heats the flue gas in the circulating water reheater 5, raising the flue gas temperature above the dew point to prevent subsequent pipe corrosion, recovering the condensation waste heat of the refrigeration system, and reducing the overall energy consumption of the system. The wastewater reheater 6 is connected to both the boiler unit and the circulating water system. The wastewater reheater 6 uses the high-temperature wastewater discharged from the boiler unit as a heat source to reheat the flue gas a second time, further increasing the flue gas temperature so that it has sufficient elevation at the chimney outlet, making it less likely to mix with cold air and form white water mist. This recovers the waste heat of the boiler wastewater, realizing waste heat utilization, while simultaneously reducing the wastewater discharge temperature and reducing thermal pollution.

[0028] The circulating water reheater 5 and the wastewater reheater 6 are installed between the desulfurization tower 12 and the chimney in the direction of boiler flue gas flow. The circulating water reheater 5 is connected to the desulfurization tower 12 and the wastewater reheater 6 respectively, and the wastewater reheater 6 is connected to the chimney.

[0029] like Figure 1 As shown, this invention provides a method for removing whitening gas by comprehensively utilizing the heat of boiler flue gas. The method, using the aforementioned device for removing whitening gas by comprehensively utilizing the heat of boiler flue gas, specifically includes the following steps: S1. The hot flue gas from the boiler unit passes through the air preheater and the bag filter in sequence before being drawn into the induced draft fan. The flue gas after the induced draft fan first passes through the hot water cooler, then through the air cooler, and is then sent to the desulfurization tower. S2. The heat transfer water from the refrigeration unit is heated by flue gas and then enters the hot water tank. It is then sent back to the generator of the refrigeration unit for circulation by the heat transfer water circulation pump. S3. After entering the desulfurization tower, the flue gas passes through the concentration section, absorption section, water washing section, and ridge demister, and then enters the air condenser and cold water condenser. The blower sends the air to the air condenser to pre-cool the flue gas, and then the heated air is sent to the air cooler at the inlet of the desulfurization tower for heat exchange. S4. After being further heated, the air is sent to the boiler blower inlet and then enters the boiler unit. The cold water pumped by the cold water circulation pump further cools the flue gas in the cold water condenser and then returns to the refrigeration unit. The condensed liquid flows into the water circulation tank and is used as makeup water for the desulfurization tower. S5. After passing through the wire mesh demister, the flue gas is sent out of the desulfurization tower. The flue gas exiting the desulfurization tower first passes through the circulating water reheater. The circulating water with a higher temperature from the refrigeration unit heats the flue gas in the circulating water reheater. The cooled circulating water returns to the circulating water device and then passes through the boiler wastewater reheater. The boiler wastewater with a higher temperature further heats the flue gas in the wastewater reheater. The cooled boiler wastewater is sent to the circulating water device as makeup water and finally sent to the chimney for venting.

[0030] Therefore, this invention employs the aforementioned de-whitening device and method for comprehensive utilization of boiler flue gas heat. Through both air cooling and cold water cooling, water vapor in the flue gas condenses. After the water vapor condenses and precipitates, it is then captured by a demister, significantly reducing the moisture content of the flue gas and thus reducing and eliminating the "white smoke" problem. This reduces pollutant emissions and efficiently recovers and utilizes the condensate in the flue gas. Furthermore, air cooling is sufficient in winter, achieving both energy saving and whitening removal. Firstly, the desulfurization tower is circulated with recycled water. The flue gas is heated and then passed through the boiler wastewater at a higher temperature, further increasing the flue gas temperature. This reduces the load on the circulating water cooling tower and improves the whitening effect of the flue gas after the flue gas temperature is increased, while also slowing down corrosion in the flue. The hot air, which has been heated twice by the air condenser and air preheater, is then sent to the inlet of the blower, which increases the inlet air temperature of the blower and the wall temperature of the heat exchange tubes in the boiler air preheater. This increase in air temperature is particularly beneficial for improving the boiler's operating conditions in winter, reducing the rate of air preheater blockage, and improving the economic efficiency of boiler operation.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A desulfurization device for comprehensive utilization of boiler flue gas heat, characterized in that: It includes a whitening system, which is connected to a refrigeration system, an air-cooling system, and a reheating system. The whitening system includes a boiler unit, which is connected to an air preheater, which is connected to a bag filter, which is connected to an induced draft fan, which is connected to a desulfurization tower, and the desulfurization tower is connected to a chimney.

2. The desulfurization device for comprehensive utilization of boiler flue gas heat according to claim 1, characterized in that: The refrigeration system includes a refrigeration unit, which is connected to a chilled water circulating pump and a hot water cooler. The chilled water circulating pump is connected to a chilled water condenser, the chilled water condenser is connected to the refrigeration unit, the hot water cooler is connected to a hot water tank, the hot water tank is connected to a hot water circulating pump, and the hot water circulating pump is connected to the refrigeration unit.

3. The desulfurization device for comprehensive utilization of boiler flue gas heat according to claim 2, characterized in that: The air-cooled system includes a blower, which is connected to an air condenser, which is connected to an air cooler, which is connected to a blower, and the blower is connected to an air preheater.

4. The desulfurization device for comprehensive utilization of boiler flue gas heat according to claim 3, characterized in that: The reheat system includes a circulating water reheater and a wastewater reheater. The circulating water reheater is connected to the chiller unit and the circulating water system, respectively, and the wastewater reheater is connected to the boiler unit and the circulating water system, respectively.

5. The desulfurization device for comprehensive utilization of boiler flue gas heat according to claim 4, characterized in that: The heat transfer water cooler and the air cooler are installed between the induced draft fan and the desulfurization tower according to the direction of boiler flue gas flow. The heat transfer water cooler is connected to the induced draft fan and the air cooler respectively, and the air cooler is connected to the desulfurization tower.

6. The desulfurization device for comprehensive utilization of boiler flue gas heat according to claim 5, characterized in that: The desulfurization tower is equipped with a concentration section, an absorption section, and a water washing section. The concentration section is located at the bottom of the desulfurization tower, and the absorption section is located between the concentration section and the water washing section. The desulfurization tower above the water washing section is equipped with a ridge demister, an air condenser, a cold water condenser, and a wire mesh demister. The air condenser and the cold water condenser are located between the ridge demister and the wire mesh demister, the cold water condenser is located above the air condenser, and the wire mesh demister is located above the cold water condenser.

7. A desulfurization device for comprehensive utilization of boiler flue gas heat according to claim 6, characterized in that: The circulating water reheater and the wastewater reheater are installed between the desulfurization tower and the chimney according to the direction of boiler flue gas flow. The circulating water reheater is connected to the desulfurization tower and the wastewater reheater respectively, and the wastewater reheater is connected to the chimney.

8. A desulfurization device for comprehensive utilization of boiler flue gas heat according to claim 7, characterized in that: The boiler unit is connected to the hot water tank, the desulfurization tower is connected to the water circulation tank, and the air cooler is equipped with an air cooler branch line.

9. A method for removing whitening gas from boiler flue gas by comprehensively utilizing heat, using the whitening device for comprehensively utilizing heat from boiler flue gas according to any one of claims 1-8, characterized in that: Specifically, the following steps are included: S1. The hot flue gas from the boiler unit passes through the air preheater and the bag filter in sequence before being drawn into the induced draft fan. The flue gas after the induced draft fan first passes through the hot water cooler, then through the air cooler, and is then sent to the desulfurization tower. S2. The heat transfer water from the refrigeration unit is heated by flue gas and then enters the hot water tank. It is then sent back to the generator of the refrigeration unit for circulation by the heat transfer water circulation pump. S3. After entering the desulfurization tower, the flue gas passes through the concentration section, absorption section, water washing section, and ridge demister, and then enters the air condenser and cold water condenser. The blower sends the air to the air condenser to pre-cool the flue gas, and then the heated air is sent to the air cooler at the inlet of the desulfurization tower for heat exchange. S4. After being further heated, the air is sent to the boiler blower inlet and then enters the boiler unit. The cold water pumped by the cold water circulation pump further cools the flue gas in the cold water condenser and then returns to the refrigeration unit. The condensed liquid flows into the water circulation tank and is used as makeup water for the desulfurization tower. S5. After passing through the wire mesh demister, the flue gas is sent out of the desulfurization tower. The flue gas exiting the desulfurization tower first passes through the circulating water reheater. The circulating water with a higher temperature from the refrigeration unit heats the flue gas in the circulating water reheater. The cooled circulating water returns to the circulating water device and then passes through the boiler wastewater reheater. The boiler wastewater with a higher temperature further heats the flue gas in the wastewater reheater. The cooled boiler wastewater is sent to the circulating water device as makeup water and finally sent to the chimney for venting.

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