Household garbage incineration flue gas purification method

Abstract

The invention relates to the technical field of environmental protection, in particular to a household garbage incineration flue gas purification method. The method is characterized in that gaseous pollutants generated after municipal solid waste incineration are purified by adopting an injection-atomization fluidization method, a gas phase in fluidization is the gaseous pollutants and steam, a liquid phase in fluidization is an atomized aqueous solution, a solid phase in fluidization is Ca (OH) 2 solid particles and smoke dust, contact, mass transfer and heat transfer between the phases are greatly enhanced by strongly turbulent fluid, and the purification reaction rate is increased. Acid gas in the gaseous pollutants can adopt Ca (OH) 2 to generate corresponding alkaline earth metal halide, sulfate, sulfite, phosphate and carbonate, and organic gaseous pollutants and gaseous heavy metal in the gaseous pollutants are condensed on the surface of Ca (OH) 2 solid at a proper environment temperature to capture Ca (OH) 2 solid particles.

Description

Technical Field

[0001] The invention relates to the technical field of environmental protection, and in particular to a method for purifying flue gas from the incineration of domestic waste. Background Art

[0002] The disposal method of incineration of municipal solid waste makes pollutants develop in the direction of reduction, harmlessness and resource utilization. The gaseous pollutants generated after the incineration of organic carbon, organic sulfur, organic phosphorus, organic chloride, organic fluoride and inorganic compounds in municipal solid waste include CO2, SO2, SO3, P2O5, HF, HCl, Hg, Pb, Cd, dioxin, furan, smoke, etc., which can be roughly divided into several categories such as acid gas pollutants, organic gaseous pollutants, gaseous heavy metals, smoke, etc. The Chinese invention patent (patent number CN200410101859, patent name is a circulating fluidized bed boiler incineration garbage and tail gas purification integrated device) discloses a circulating fluidized bed boiler incineration garbage and tail gas purification integrated device, characterized in that it includes a circulating fluidized bed boiler furnace, a cyclone separator, a cooling tower and a bag filter. Its structural features are that a primary air inlet is arranged at the bottom of the furnace body, a garbage material and limestone powder removal agent inlet is arranged at the middle and lower part of the furnace body, and the upper side of the furnace body is connected to the cyclone separator through a flue. The lower part of the cyclone separator is connected to the material return mechanism, the bottom of the material return mechanism is connected to the bottom of the furnace body, and the top of the cyclone separator is connected to the bottom of the cooling tower through a flue. The cooling tower is built with multiple groups of water nozzles in the opposite direction of the flue gas flow, and the top of the cooling tower is connected to the bag filter through a bend flue, and an iron fly ash inlet and an activated carbon inlet are arranged on the bend flue. A purified air outlet connected to the induced draft fan is arranged on the upper side of the bag filter, and a vertically arranged filter material layer is built into the bag filter. In the above-mentioned integrated device, the bend flue is in the shape of a bend flue, and an iron fly ash inlet is arranged on the vertical section of the bend flue, and an activated carbon inlet is arranged on the parallel section of the bend flue. In the above-mentioned integrated device, two groups of water nozzles are arranged in the cooling tower. In the above-mentioned integrated device, the filter material layer adopts a membrane filter material.

[0003] Prior art A circulating fluidized bed boiler for incinerating garbage and purifying tail gas is an integrated device. A circulating fluidized bed boiler is used to incinerate garbage. Limestone is sprayed into the furnace to remove acidic gas. The main component of limestone is calcium carbonate. It is calcined in the furnace to generate calcium oxide and carbon dioxide gas. At this time, acidic gases such as SO2, SO3, P2O5, HF, and HCl are all in the state of gas molecules. At a high temperature of 650 to 750°C in the furnace, the acidic gas molecules move violently, and the van der Waals force between the molecules on the surface of the solid particles is correspondingly weakened, that is, the adsorption force of the solid-gas two-phase interface is weakened, that is, the gas molecules cannot diffuse through the solid surface and enter the internal voids of the solid to react with it. Moreover, due to the expansion of the gas volume, the molecular distance is greatly increased, and the collision probability of the gas-solid two-phase is greatly reduced. Therefore, it is difficult for calcium oxide solid to react with acidic gas under high temperature conditions in the furnace, and the technical route of spraying limestone into the furnace to purify acidic gas is not feasible. Summary of the invention

[0004] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a method for purifying flue gas from the incineration of municipal solid waste, which is characterized by: using a jet-atomization fluidization method to purify gaseous pollutants generated after the incineration of municipal solid waste, the gas phase in the fluidization is gaseous pollutants and steam, the liquid phase is an atomized aqueous solution, and the solid phase is Ca(OH)2 solid particles and smoke dust, and the strongly turbulent fluid greatly enhances the contact, mass transfer and heat transfer between the phases, thereby increasing the purification reaction rate. The acidic gases in the gaseous pollutants can be converted into corresponding alkaline earth metal halides, sulfates, sulfites, phosphates and carbonates using Ca(OH)2, and the organic gaseous pollutants and gaseous heavy metals in the gaseous pollutants condense on the surface of the Ca(OH)2 solid at a suitable ambient temperature and are captured by the Ca(OH)2 solid particles.

[0005] Step 1: Recover waste heat to produce steam. The flue gas outlet temperature of municipal solid waste incinerators is generally high. Before entering the jet-atomized fluidized bed, a waste heat recovery flue is designed to cool the flue gas and recover the waste heat. Considering the dew point temperature of the pollutant SO2, the exhaust temperature of the waste heat recovery flue is designed to be 155-160°C. Three sets of independent evaporators are designed in the waste heat recovery flue along the flue gas flow direction. Because the heating temperature of each set of evaporators in the flue is different, the metal pipe wall of the evaporation heating surface cannot be sufficiently cooled, which will increase the temperature and cause the strength to decrease. , the water circulation must be normal, so each group of evaporators is designed with a lower header, a centralized water supply pipe, a centralized downcomer, a water-cooled wall, and an upper header. The water circulation adopts a natural circulation method. The steam-water mixture after the water-cooled wall is heated is introduced into the boiler drum through the upper header. The steam-water separator in the boiler drum separates the steam-water mixture. The fresh water and the circulating water are collected in the lower header through the centralized downcomer and then distributed to the water-cooled wall with uneven heating. The flue gas flows through the flue and collides with the water-cooled wall. The particles that lose kinetic energy are collected in the dust collecting chamber, and the particles adhering to the water-cooled wall are blown off into the dust collecting chamber by steam.

[0006] Step 2: Purification by spray-atomization fluidization method. Since the reaction rate of gas-solid phase is extremely low, the ambient temperature must be lowered to 80-90°C. The atomized aqueous solution is adsorbed on the surface of Ca(OH)2 solid particles to form a water film, which can be regarded as a film composed of aqueous solution. The water molecules destroy the Ca(OH)2 lattice on the crystal surface and produce a hydration reaction. Ca 2+ Cation and OH - When anions enter the aqueous solution, due to the polarity of water molecules, gaseous pollutants are also adsorbed and dissolved by the water film, among which H + With OH - Neutralization, Ca 2+ The cations associate with other halide anions and acid anions to form ion pairs. The above-mentioned calcium salts precipitate and cover the surface of solid particles after the aqueous solution is supersaturated, hindering the reaction from continuing. The solid particles need to be dragged by gas-liquid two-phase fluid to flow. The solid particles will fall off the covering calcium salt layer during mutual collision, exposing fresh Ca(OH)2 to continue the reaction. At the same time, the organic gaseous pollutants and gaseous heavy metals in the gaseous pollutants condense on the surface of the solid particles at an ambient temperature of 80-90°C and diffuse inward through their micropores. During the adsorption by the solid particles, complex physical adsorption and chemical adsorption processes occur. Physical adsorption is manifested as the release of adsorption heat, and chemical adsorption generates stable ionic compounds and molecular complexes. Under normal circumstances, organic gaseous pollutants and gaseous heavy metals can no longer be desorbed from solid particles, because desorption requires a temperature much higher than the ambient temperature to overcome the electrostatic force, covalent bond force, and intermolecular force in the solid phase.

[0007] The injection-atomization fluidized bed is designed with Laval steam injection tube, screw feeder, overflow return feeder, riser, fluidized bed, and cyclone separator. The fluidized bed is composed of a jet chamber, a throat orifice plate, a diffusion chamber, and a fluidizing chamber from bottom to top, forming a venturi tube structure. The working steam is accelerated to the speed of sound through the Laval steam injection tube and sprayed into the jet chamber. The pressure energy is converted into kinetic energy, thereby forming a low pressure in the jet chamber, guiding the flue gas into the jet chamber to mix with the working steam. The throat orifice plate is designed with a central through hole with a larger diameter, and air distribution pipes with smaller diameters are evenly distributed along the circumferential direction. A water tank is designed in the throat orifice plate. The working steam enters the diffusion chamber through the central through hole, and the smoke enters the diffusion chamber through the air distribution pipe. The cold water in the water tank is sprayed into the air distribution pipe through the water injection hole of the air distribution pipe to mix with the flue gas and atomize. When the flue gas passes through the throat orifice plate, the temperature drops to 80-90°C, and Ca(OH)2 solid particles with a diameter of 4-8mm are fed into the diffusion chamber through the screw feeder. In the room, it is dragged by the gas-liquid two-phase fluid to flow. In the dense phase area below, the mixed fluid is mainly bubbling and circular flow, ensuring that the Ca(OH)2 crystals complete the chemical reaction with the participation of the aqueous solution. In the dilute phase area above, the fluid is in a fast flow state, including the central axial jet and the regular circulation flow around. The working steam completes the exchange of momentum and kinetic energy with the flue gas in the diffusion chamber and the fluidizing chamber, and finally the speed tends to be consistent to complete the fluidization process. Due to the heat exchange of the working steam, the fluid temperature rises to 110°C, and the water in the fluid absorbs heat and turns into water vapor. Because the pollutants in the discharged fluid after purification by the fluidized bed are particulate matter, the subsequent purification facilities should choose a gas-solid separator. The liquid water must be evaporated into steam in the gas phase to ensure the normal operation of the purification facilities.

[0008] After the fluid is separated into gas and solid by the cyclone separator, the separated gas fluid mainly includes nitrogen, water vapor and small-diameter particles. The small-diameter particles are further separated into gas and solid by the bag dust collector and discharged; the separated larger-diameter particles fill the riser and go down to the overflow return material device, and return to the fluidized bed through the overflow return material device. The overflow return material device is designed with an overflow weir plate, a fluidized loosening chamber, an air distribution plate, and a steam chamber. Since the fluidized bed body is a high-pressure area and the fluidized bed body is a low-pressure area, the two areas are separated by an overflow weir plate, and the larger-diameter particles are discharged. Two conditions are required for particles to overflow from the low-pressure area to the high-pressure area. The first is to fluidize the larger diameter particles, that is, to inject the working steam through the steam chamber through the air distribution plate into the fluidizing loosening chamber to mix with the larger diameter particles, dragging the larger diameter particles to flow, and the pressure energy of the working steam is converted into kinetic energy and energizes the larger diameter particles to overflow to the high-pressure area. The second is that the static pressure head formed by the larger diameter particles filled in the riser is sufficient to overcome the pressure difference between the high and low pressure areas, ensuring that the larger diameter particles are continuously transported into the fluidized bed.

[0009] Compared with the prior art, the present invention has at least the following advantages: the injection-atomization fluidization method is used to purify the flue gas from the incineration of urban domestic waste, and the gas-liquid-solid three-phase can fully transfer mass and heat, so that the flue gas purification reaction efficiency can be greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of the main structure of a method for purifying flue gas from the incineration of domestic waste according to the present invention.

[0011] Figure 2 It is a left-side structural schematic diagram of a method for purifying flue gas from incineration of domestic waste according to the present invention.

[0012] Figure 3 This is a schematic diagram of the AA cross-sectional structure of a method for purifying flue gas from domestic waste incineration according to the present invention.

[0013] Figure 4 It is a schematic diagram of the BB cross-sectional structure of a method for purifying flue gas from domestic waste incineration according to the present invention.

[0014] Figure 5 This is a schematic diagram of the C-sample structure of a method for purifying flue gas from the incineration of domestic waste according to the present invention.

[0015] Figure 6 This is a schematic diagram of the D-scale structure of a method for purifying flue gas from the incineration of domestic waste according to the present invention.

[0016] Figure 7 This is a schematic diagram of the E-sample structure of a method for purifying flue gas from the incineration of domestic waste according to the present invention.

[0017] Ⅰ- Waste heat recovery flue Ⅱ- Injection-atomization fluidized bed Ⅲ- Bag filter 1-Lower header 2-Central water supply pipe 3-Central downcomer 4-Water cooling wall 5-Upper header 6-boiler drum 7-flue 8-dust chamber 9-Laval steam injection pipe 10-screw feeder 11-overflow return device 12-vertical pipe 13-fluidized bed 14-cyclone separator 15-jet chamber 16-throat orifice plate 17-diffusion chamber 18 - Fluidizing chamber 19 - Air distribution pipe 20 - Central through hole 21 - Water injection hole 22 - Water tank 23 - overflow weir plate 24 - fluidizing loosening chamber 25 - air distribution plate 26 - steam chamber. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0019] like Figure 1 , Figure 2, Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 As shown, a method for purifying flue gas from the incineration of municipal solid waste is characterized in that: the gaseous pollutants generated after the incineration of municipal solid waste are purified by the injection-atomization fluidization method, the gas phase in the fluidization is gaseous pollutants and steam, the liquid phase is an atomized aqueous solution, and the solid phase is Ca(OH)2 solid particles and smoke dust. The strongly turbulent fluid greatly enhances the contact, mass transfer and heat transfer between the phases, and improves the purification reaction rate. The acidic gas in the gaseous pollutants can be converted into corresponding alkaline earth metal halides, sulfates, sulfites, phosphates, and carbonates by using Ca(OH)2, and the organic gaseous pollutants and gaseous heavy metals in the gaseous pollutants condense on the surface of the Ca(OH)2 solid at a suitable ambient temperature and are captured by the Ca(OH)2 solid particles.

[0020] Step 1: Recover waste heat to produce steam. The flue gas outlet temperature of municipal solid waste incinerators is generally high. Before entering the injection-atomization fluidized bed II, a waste heat recovery flue I is designed to cool the flue gas and recover the waste heat. Considering the dew point temperature of the pollutant SO2, the exhaust temperature of the waste heat recovery flue I is designed to be 155-160°C. Three sets of independent evaporators are designed in the waste heat recovery flue I along the flue gas flow direction. Because the heating temperature of each set of evaporators in the flue 7 is different, the metal tube wall of the evaporation heating surface cannot be sufficiently cooled, which will increase the temperature and cause the strength to decrease. It is necessary to ensure that the water The circulation is normal, so each group of evaporators is designed with a lower header 1, a centralized water supply pipe 2, a centralized downcomer 3, a water-cooled wall 4, and an upper header 5. The water circulation adopts a natural circulation method. The steam-water mixture after the water-cooled wall 4 is heated is introduced into the boiler drum 6 through the upper header 5. The steam-water separator in the boiler drum 6 separates the steam-water mixture. The fresh water and the circulating water are collected into the lower header 1 through the centralized downcomer 3 and then distributed to the water-cooled wall 4 which is heated unevenly. The flue gas flows through the flue 7 and collides with the water-cooled wall 4. The particles that lose kinetic energy are collected in the dust collecting chamber 8. The particles adhering to the water-cooled wall 4 are blown off by steam into the dust collecting chamber 8.

[0021] Step 2: Purification by spray-atomization fluidization method. Since the reaction rate of gas-solid phase is extremely low, the ambient temperature must be lowered to 80-90°C. The atomized aqueous solution is adsorbed on the surface of Ca(OH)2 solid particles to form a water film, which can be regarded as a film composed of aqueous solution. The water molecules destroy the Ca(OH)2 lattice on the crystal surface and produce a hydration reaction. Ca 2+ Cation and OH - When anions enter the aqueous solution, due to the polarity of water molecules, gaseous pollutants are also adsorbed and dissolved by the water film, among which H + With OH - Neutralization, Ca 2+The cations associate with other halide anions and acid anions to form ion pairs. The above-mentioned calcium salts precipitate and cover the surface of solid particles after the aqueous solution is supersaturated, hindering the reaction from continuing. The solid particles need to be dragged by gas-liquid two-phase fluid to flow. The solid particles will fall off the covering calcium salt layer during mutual collision, exposing fresh Ca(OH)2 to continue the reaction. At the same time, the organic gaseous pollutants and gaseous heavy metals in the gaseous pollutants condense on the surface of the solid particles at an ambient temperature of 80-90°C and diffuse inward through their micropores. During the adsorption by the solid particles, complex physical adsorption and chemical adsorption processes occur. Physical adsorption is manifested as the release of adsorption heat, and chemical adsorption generates stable ionic compounds and molecular complexes. Under normal circumstances, organic gaseous pollutants and gaseous heavy metals can no longer be desorbed from solid particles, because desorption requires a temperature much higher than the ambient temperature to overcome the electrostatic force, covalent bond force, and intermolecular force in the solid phase.

[0022] The spray-atomization fluidized bed is designed with a Laval steam spray pipe 9, a screw feeder 10, an overflow return device 11, a vertical pipe 12, a fluidized bed body 13, and a cyclone separator 14. The fluidized bed 13 is composed of a jet chamber 15, a throat orifice plate 16, a diffusion chamber 17, and a fluidizing chamber 18 from bottom to top, forming a venturi tube structure. The working steam is accelerated to the speed of sound through the Laval steam jet pipe 9 and sprayed into the jet chamber 15. The pressure energy is converted into kinetic energy, thereby forming a low pressure in the jet chamber 15, guiding the flue gas into the jet chamber 15 and mixing with the working steam. The throat orifice plate 16 is designed with a central through hole 20 with a larger diameter, and gas distribution pipes 19 with smaller diameters are uniformly distributed along the circumferential direction. A water tank 22 is designed in the throat orifice plate 16. The working steam enters the diffusion chamber 17 through the central through hole 20, and the smoke enters the diffusion chamber 17 through the gas distribution pipe 19. The cold water in the water tank is sprayed into the gas distribution pipe 19 through the water injection hole 21 of the gas distribution pipe 19 and mixed with the flue gas to be atomized. When the flue gas passes through the throat orifice plate 16, the temperature drops to 80-90°C, and the Ca(OH) )2 Solid particles are fed into the diffusion chamber 17 through the screw feeder 10 and are dragged by the gas-liquid two-phase fluid to flow. In the dense phase area below, the mixed fluid is mainly bubbling and circular flow, ensuring that the Ca(OH)2 crystals complete the chemical reaction with the participation of the aqueous solution. In the dilute phase area above, the fluid is in a fast flow state, including a central axial jet and a regular circulating flow around. The working steam completes the exchange of momentum and kinetic energy with the flue gas in the diffusion chamber 17 and the fluidizing chamber 18, and finally the speed tends to be consistent to complete the fluidization process. Due to the heat exchange effect of the working steam, the fluid temperature rises to 110°C, and the water in the fluid absorbs heat and turns into water vapor. Because the pollutants in the discharged fluid after purification by the fluidized bed are particulate matter, the subsequent purification facilities should select a gas-solid separator, and the liquid water must be evaporated into steam in the gas phase to ensure the normal operation of the purification facilities.

[0023] After the fluid is separated into gas and solid by the cyclone separator 14, the separated gas fluid mainly includes nitrogen, water vapor and small-diameter particles. The small-diameter particles are further separated into gas and solid by the bag filter III and then discharged; the separated larger-diameter particles fill the riser 12 and go down to the overflow return device 11, and return to the fluidized bed 13 through the overflow return device 11. The overflow return device 11 is designed with an overflow weir plate 23, a fluidized loosening chamber 24, an air distribution plate 25, and a steam chamber 26. Since the fluidized bed 13 is a high-pressure area and the outside of the fluidized bed 13 is a low-pressure area, an overflow weir plate 25 is used between the two areas. 3, the overflow of larger diameter particles from the low pressure area to the high pressure area requires two conditions: first, the larger diameter particles are fluidized, that is, the working steam is injected into the fluidizing loosening chamber 24 through the steam chamber 26 through the air distribution plate 25 to mix with the larger diameter particles, dragging the larger diameter particles to flow, and the pressure energy of the working steam is converted into kinetic energy and energizes the larger diameter particles to overflow to the high pressure area; second, the static pressure head formed by the larger diameter particles filled in the riser 12 is sufficient to overcome the pressure difference between the high and low pressure areas, ensuring that the larger diameter particles are continuously transported into the fluidized bed 13.

Claims

1. A method for purifying flue gas from the incineration of domestic waste, characterized in that: Step 1: Recover waste heat to produce steam. The flue gas outlet temperature of municipal solid waste incinerators is generally high. Before entering the jet-atomized fluidized bed, a waste heat recovery flue is designed to cool the flue gas and recover the waste heat. Considering the dew point temperature of the pollutant SO2, the exhaust temperature of the waste heat recovery flue is designed to be 155-160°C. Three sets of independent evaporators are designed in the waste heat recovery flue along the flue gas flow direction. Because the heating temperature of each set of evaporators in the flue is different, the metal pipe wall of the evaporation heating surface cannot be sufficiently cooled, which will increase the temperature and cause the strength to decrease. Water circulation must be ensured. Normal, so each group of evaporators is designed with a lower header, a centralized water supply pipe, a centralized downcomer, a water-cooled wall, and an upper header. The water circulation adopts a natural circulation method. The steam-water mixture after the water-cooled wall is heated is introduced into the boiler drum through the upper header. The steam-water separator in the boiler drum separates the steam-water mixture. The fresh water and the circulating water are collected in the lower header through the centralized downcomer and then distributed to the water-cooled wall with uneven heating. The flue gas flows through the flue and collides with the water-cooled wall. The particles that lose kinetic energy are collected in the dust collecting chamber. The particles adhering to the water-cooled wall are blown off by steam to the dust collecting chamber; Step 2, purification by spray-atomization fluidization method, The spray-atomization fluidized bed is designed with Laval steam injection pipe, screw feeder, overflow return feeder, vertical pipe, fluidized bed body, cyclone separator. The working steam is accelerated to the speed of sound through the Laval steam injection pipe and injected into the jet chamber. The pressure energy is converted into kinetic energy, thereby forming a low pressure in the jet chamber, guiding the flue gas into the jet chamber to mix with the working steam. The throat orifice plate is designed with a central through hole with a larger diameter, and air distribution pipes with smaller diameters are evenly distributed along the circumferential direction. A water tank is designed in the throat orifice plate. The working steam enters the diffusion chamber through the central through hole, and the extracted flue gas enters the diffusion chamber through the air distribution pipe. In the diffusion chamber, cold water in the water tank is sprayed into the air distribution pipe through the water injection hole of the air distribution pipe to mix with the flue gas and atomize. When the flue gas passes through the throat orifice plate, the temperature drops to 80-90°C. Ca(OH)2 solid particles with a diameter of 4-8mm are sent into the diffusion chamber through a screw feeder and are dragged by the gas-liquid two-phase fluid. The working steam completes the exchange of momentum and kinetic energy with the flue gas in the diffusion chamber and the fluidizing chamber, and finally the speed tends to be consistent to complete the fluidization process. Due to the heat exchange of the working steam, the fluid temperature rises to 110°C, and the water in the fluid absorbs heat and turns into water vapor. After the fluid is separated into gas and solid by the cyclone separator, the separated gas fluid mainly includes nitrogen, water vapor and small-diameter particles. The small-diameter particles are further separated into gas and solid by the bag dust collector and then discharged; the separated larger-diameter particles fill the riser and go down to the overflow return device, and return to the fluidized bed through the overflow return device. The overflow return device is designed with an overflow weir plate, a fluidized loosening chamber, an air distribution plate and a steam chamber. Since the inside of the fluidized bed is a high-pressure area and the outside of the fluidized bed is a low-pressure area, the two areas are separated by an overflow weir plate.

2. The method for purifying flue gas from incineration of domestic waste according to claim 1, characterized in that: The spray-atomization fluidization method is used to purify the gaseous pollutants generated after the incineration of urban domestic waste. The gas phase in the fluidization is gaseous pollutants and steam, the liquid phase is atomized aqueous solution, and the solid phase is Ca(OH)2 solid particles and smoke. The strongly turbulent fluid greatly enhances the contact, mass transfer and heat transfer between the phases, and improves the purification reaction rate. The acidic gases in the gaseous pollutants can be converted into corresponding alkaline earth metal halides, sulfates, sulfites, phosphates, and carbonates using Ca(OH)2. The organic gaseous pollutants and gaseous heavy metals in the gaseous pollutants condense on the surface of the Ca(OH)2 solid at a suitable ambient temperature and are captured by the Ca(OH)2 solid particles.

3. A method for purifying flue gas from incineration of domestic waste according to claim 1, characterized in that: The reaction rate of the gas-solid two-phase is extremely low, and the ambient temperature must be reduced to 80-90°C. The atomized aqueous solution is adsorbed on the surface of the Ca(OH)2 solid particles to form a water film, which can be regarded as a thin film composed of aqueous solution. The water molecules destroy the Ca(OH)2 lattice on the crystal surface and produce a hydration reaction. Ca 2+ Cation and OH - When anions enter the aqueous solution, due to the polarity of water molecules, gaseous pollutants are also adsorbed and dissolved by the water film, among which H + With OH - Neutralization, Ca 2+ The cations associate with other halide anions and acid anions to form ion pairs. After the aqueous solution is supersaturated, the above-mentioned calcium salts precipitate and cover the surface of the solid particles, hindering the continued reaction. The gas-liquid two-phase fluid is required to drag the solid particles to flow. The solid particles will fall off the covering calcium salt layer during mutual collisions, exposing fresh Ca(OH)2 to continue the reaction.

4. A method for purifying flue gas from incineration of domestic waste according to claim 1, characterized in that: Organic gaseous pollutants and gaseous heavy metals in gaseous pollutants condense on the surface of solid particles at an ambient temperature of 80 to 90°C and diffuse inward through their micropores. During adsorption by solid particles, complex physical adsorption and chemical adsorption processes occur. Physical adsorption is manifested as the release of adsorption heat, while chemical adsorption generates stable ionic compounds and molecular complexes. Under normal circumstances, organic gaseous pollutants and gaseous heavy metals can no longer be desorbed from solid particles, because desorption requires a temperature much higher than the ambient temperature to overcome the electrostatic force, covalent bond force, and intermolecular force in the solid phase.

5. A method for purifying flue gas from incineration of domestic waste according to claim 1, characterized in that: The fluidized bed is composed of a jet chamber, a throat orifice plate, a diffusion chamber, and a fluidizing chamber from bottom to top, forming a venturi tube structure.

6. A method for purifying flue gas from incineration of domestic waste according to claim 1, characterized in that: In the dense phase area below, the mixed fluid mainly flows in the form of bubbling and circular flow, ensuring that the Ca(OH)2 crystals complete the chemical reaction with the participation of the aqueous solution. In the dilute phase area above, the fluid flows rapidly, including the central axial jet and regular circulating flow around it.

7. A method for purifying flue gas from incineration of domestic waste according to claim 1, characterized in that: Because the pollutants in the discharge fluid after purification by the fluidized bed are particulate matter, the subsequent purification facilities should use a gas-solid separator, and the liquid water must be evaporated into steam in the gas phase to ensure the normal operation of the purification facilities.

8. The method for purifying flue gas from incineration of domestic waste according to claim 1, characterized in that: Two conditions are required for larger diameter particles to overflow from the low-pressure area to the high-pressure area. First, the larger diameter particles should be fluidized, that is, the working steam is injected into the fluidizing loosening chamber through the steam chamber through the air distribution plate to mix with the larger diameter particles, dragging the larger diameter particles to flow. The pressure energy of the working steam is converted into kinetic energy and energizes the larger diameter particles to overflow to the high-pressure area. Second, the static pressure head formed by the larger diameter particles filled in the riser is sufficient to overcome the pressure difference between the high and low pressure areas, ensuring that the larger diameter particles are continuously transported into the fluidized bed.

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