WO2021128472A1 - 一种电解铝烟气半干法脱硫脱氟系统及方法 - Google Patents

一种电解铝烟气半干法脱硫脱氟系统及方法 Download PDF

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WO2021128472A1
WO2021128472A1 PCT/CN2020/070702 CN2020070702W WO2021128472A1 WO 2021128472 A1 WO2021128472 A1 WO 2021128472A1 CN 2020070702 W CN2020070702 W CN 2020070702W WO 2021128472 A1 WO2021128472 A1 WO 2021128472A1
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Prior art keywords
flue gas
electrolytic aluminum
defluorination
slaked lime
desulfurization
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English (en)
French (fr)
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朱廷钰
刘霄龙
刘法高
王雪
刘�文
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Institute of Process Engineering of CAS
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Institute of Process Engineering of CAS
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides
    • B01D53/508—Sulfur oxides by treating the gases with solids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/68—Halogens or halogen compounds
    • B01D53/685—Halogens or halogen compounds by treating the gases with solids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/40—Alkaline earth metal or magnesium compounds
    • B01D2251/404—Alkaline earth metal or magnesium compounds of calcium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/60—Inorganic bases or salts
    • B01D2251/604—Hydroxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/20—Halogens or halogen compounds
    • B01D2257/204—Inorganic halogen compounds
    • B01D2257/2047—Hydrofluoric acid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases

Definitions

  • the application belongs to the field of industrial waste gas treatment, and relates to a desulfurization and defluorination system and method, for example, to a semi-dry desulfurization and defluorination system and method for electrolytic aluminum flue gas.
  • Aluminum electrolysis produces about 15-40kg/t-Al of fluorine per ton of aluminum and 4-16kg/t-Al of sulfur dioxide.
  • the flue gas treatment methods of the electrolytic cell include wet purification and dry purification.
  • the dry purification is to use a gas collecting hood arranged on the upper part of the electrolytic tank to capture the flue gas into the purification facility, in the purification facility, the electrolytic raw material alumina is used to adsorb the hydrogen fluoride in the flue gas, and then the gas-solid separation is achieved through a bag filter.
  • the alumina after absorbing fluorine is returned to the electrolytic cell as raw material for electrolysis production, and the fluorine absorbed by the alumina replenishes the fluoride salt electrolyte required by the electrolysis process.
  • CN 208055476 U discloses a dry purification device for removing fluoride from electrolytic aluminum flue gas, which includes a flue gas inlet pipe.
  • One end of the flue gas inlet pipe is connected to the air inlet of the first exhaust fan.
  • the air outlet of the machine is connected to the left side wall of the reaction tank through a connecting pipe.
  • the outer surface of the reaction tank is fixedly sleeved with a first gear.
  • the reaction tank is installed on a bracket.
  • a motor is installed on the bracket. The spindle end of the motor is fixedly connected with The second gear, the upper end of the reaction tank is inlaid with an alumina material tank, and the bottom of the alumina material tank is equipped with a discharge pipe.
  • the bottom end of the discharge pipe penetrates the top wall of the reaction tank and is located inside the reaction tank, and the discharge pipe
  • a solenoid valve is installed on the upper side of the reaction tank, and an electric push rod is installed on the left side wall of the reaction
  • the concentration of sulfur dioxide in the flue gas can still reach 150-300 mg/Nm 3 and the concentration of fluoride is 2-6 mg/Nm 3 , which cannot meet the national ultra-low emission standards.
  • the above-mentioned purification device can only treat fluoride and dust in the alumina flue gas, and has no purification effect on sulfur dioxide.
  • CN 208130773 U discloses a high-efficiency and energy-saving electrolytic aluminum flue gas desulfurization device, which includes an electrolytic aluminum flue gas dry process system.
  • the electrolytic aluminum flue gas desulfurization device passes the flue gas processed by the electrolytic aluminum dry process system through a fan into a setting In the box with water, the SO 2 in the flue gas after the electrolytic aluminum dry process is absorbed by the water.
  • CN 107233793 A discloses an electrolytic aluminum flue gas desulfurization device and a desulfurization method. The method connects the flue gas from the electrolytic aluminum flue gas dry method system with a fluidized boiling box, and the flue gas from the fluidized boiling box Then it is discharged through the chimney.
  • CN 109589750 A discloses an economical desulfurization and defluorination process for aluminum electrolysis flue gas.
  • the process uses the electrolysis flue gas treated by a dry purification system to have the characteristics of low pollutant content, and generally SO 2 ⁇ 300mg/Nm 3.
  • HF ⁇ 3mg/Nm 3 a spray tower is built after the dry flue gas purification system.
  • the electrolytic aluminum flue gas is washed again with water in the spray tower. SO 2 , HF and water merge to make the flue gas
  • the pollutants are further removed, and the ultra-low emission indicators of SO 2 ⁇ 35mg/Nm 3 and HF ⁇ 0.3mg/Nm 3 in the flue gas are achieved.
  • CN 109224827 A discloses a zero-emission wet desulfurization system for electrolytic aluminum production system, which includes a limestone slurry supply system, a flue gas system, an SO 2 absorption system and a gypsum dehydration system.
  • the system can reduce pollutants such as hydrogen fluoride, asphalt rubber oil, particulate matter, and sulfur dioxide emitted during the production of electrolytic aluminum.
  • wet desulfurization will inevitably bring about cooling of electrolytic aluminum flue gas, and too low flue gas temperature is likely to cause sulfuric acid The corrosion of calcium and other substances on pipelines and subsequent production equipment is not conducive to continuous production.
  • the purpose of this application is to provide a semi-dry desulfurization and defluorination system and method for electrolytic aluminum flue gas.
  • the semi-dry desulfurization and defluorination system of electrolytic aluminum flue gas greatly reduces the particle size of hydrated lime by grinding hydrated lime.
  • the desulfurization and defluorination treatment can be completed by using less ultra-fine dry slaked lime powder; the addition of steam and ultra-fine dry slaked lime powder reduces the temperature drop of the electrolytic aluminum flue gas, and the addition of steam further improves the efficiency of the electrolytic aluminum flue gas.
  • the temperature not only makes the temperature of the flue gas meet the reaction temperature window of the circulating fluidized bed, but also overcomes the defect that the electrolytic aluminum flue gas blocks the gas-solid separation device after cooling.
  • the present application provides a semi-dry desulfurization and defluorination system for electrolytic aluminum flue gas.
  • the semi-dry desulfurization and defluorination system for electrolytic aluminum flue gas includes a slaked lime supply unit, an electrolytic aluminum flue gas transport unit, and a desulfurization and desulfurization system. Fluorine unit.
  • the slaked lime supply unit includes a grinding device, the desulfurization and defluorination unit includes a circulating fluidized bed, and the electrolytic aluminum transportation unit includes an electrolytic aluminum flue gas transportation pipeline and a steam transportation pipeline.
  • the grinding device is connected with the slaked lime feed inlet of the circulating fluidized bed; the electrolytic aluminum flue gas conveying pipe and the steam conveying pipe are connected with the air inlet of the circulating fluidized bed.
  • connection mode of the electrolytic aluminum flue gas delivery pipeline and the steam delivery pipeline and the air inlet of the circulating fluidized bed described in this application includes: the electrolytic aluminum flue gas delivery pipeline and the steam delivery pipeline are independently connected to the air inlet of the circulating fluidized bed. After the port connection or the electrolytic aluminum flue gas conveying pipe is connected with the steam conveying pipe, it is connected with the air inlet of the circulating fluidized bed.
  • the particle size of dry slaked lime powder is greatly reduced by grinding slaked lime, and the desulfurization and defluorination treatment can be completed by using less ultra-fine dry slaked lime powder; the addition of steam and ultra-fine dry slaked lime powder reduces electrolytic aluminum fume
  • the temperature drop of the gas and the addition of steam further increase the temperature of the electrolytic aluminum flue gas, which not only makes the flue gas temperature meet the reaction temperature window of the circulating fluidized bed, but also overcomes the defect that the electrolytic aluminum flue gas blocks the gas-solid separation device after cooling.
  • the grinding device includes a grinder and/or a ball mill.
  • the grinder and/or ball mill described in this application are common grinders and/or ball mills in the field, and those skilled in the art can select a grinding device with appropriate parameters according to the requirements for the particle size of the dry hydrated lime powder.
  • the gas-solid separation device of the circulating fluidized bed includes a bag filter and/or a cyclone separator, and may be a bag filter.
  • the bag filter has a high trapping efficiency, and the trapping efficiency for particles below 20 ⁇ m can reach more than 99%.
  • the bag filter is mainly composed of a filter bag, a bag holder and a shell.
  • the shell is composed of a box and a clean air chamber.
  • the cloth bag is installed on the partition between the box and the clean air chamber. After the dust-containing gas enters the box, the powder produces inertia, diffusion, adhesion, and static electricity to adhere to the surface of the filter cloth.
  • the clean gas passes through the pores of the filter cloth and is discharged from the clean air chamber.
  • the dust on the filter cloth is blown back or vibrated. The function is separated from the filter cloth and falls into the hopper.
  • the temperature of the electrolytic aluminum flue gas treated by the semi-dry method is relatively low, the calcium sulfate and/or calcium sulfite entrained in the electrolytic aluminum flue gas is likely to be deposited on the filter cloth, thereby affecting the dust removal efficiency of the bag filter.
  • the particle size of dry slaked lime powder is greatly reduced by grinding slaked lime, and the desulfurization and defluorination treatment can be completed by using less ultra-fine dry slaked lime powder; the addition of steam and ultra-fine dry slaked lime powder reduces electrolytic aluminum fume
  • the temperature drop of the gas and the addition of steam further increase the temperature of the electrolytic aluminum flue gas, which not only makes the flue gas temperature meet the reaction temperature window of the circulating fluidized bed, but also overcomes the defect that the electrolytic aluminum flue gas blocks the gas-solid separation device after cooling.
  • the electrolytic aluminum flue gas semi-dry desulfurization and defluorination system further includes a slaked lime batching unit arranged before the slaked lime supply unit.
  • the slaked lime batching unit includes a water supply device, a quicklime supply device, a digestion device, and a slaked lime storage device.
  • the water supply device and the quicklime supply device are independently connected to the inlet of the digestion device, and the outlet of the digestion device It is connected with the inlet of the slaked lime storage device, and the outlet of the slaked lime storage device is connected with the inlet of the slaked lime.
  • the water provided by the water supply device and the quicklime provided by the quicklime supply device are mixed in the digestion device to complete the digestion of the quicklime.
  • the digested slaked lime in the digestion device is transferred to the slaked lime storage device under the action of the conventional slurry conveying device in the field.
  • the water supply device, quicklime supply device, digestion device, and slaked lime storage device described in this application are all water supply devices, quicklime supply devices, digestion devices, and slaked lime storage devices commonly used by those skilled in the art.
  • the water supply device includes, but is not limited to, a water supply storage tank and a matching pump;
  • the quicklime supply device includes, but is not limited to, a quicklime storage tank and a matching belt conveyor;
  • the digestion device includes, but is not limited to, a digestion tank;
  • the slaked lime storage device includes but is not limited to a slaked lime storage tank.
  • the electrolytic aluminum flue gas semi-dry desulfurization and defluorination system further includes a flue gas discharge device arranged behind the gas-solid separation device.
  • the content of SO 2 and fluoride in the electrolytic aluminum flue gas is relatively low, and can be directly discharged through the flue gas discharge device.
  • the flue gas discharge device includes an induced draft fan and a chimney that are connected in sequence, and an air inlet of the induced draft fan is connected to an exhaust outlet of the gas-solid separation device.
  • the electrolytic aluminum flue gas treated by the semi-dry desulfurization and defluorination system is discharged into the chimney through the induced draft fan and discharged from the chimney.
  • the present application provides a method for desulfurization and defluorination using the electrolytic aluminum flue gas semi-dry desulfurization and defluorination system as described in the first aspect.
  • the method includes the following steps: , Make the ground ultrafine slaked lime dry powder powder and electrolytic aluminum flue gas perform semi-dry desulfurization and defluorination in a circulating fluidized bed to obtain desulfurization and defluorination gas.
  • the ultra-fine dry slaked lime powder described in this application is dry slaked lime powder with a particle size D90 of 500-1000 mesh.
  • the dry ultra-fine slaked lime powder and electrolytic aluminum flue gas are subjected to semi-dry desulfurization and defluorination in a circulating fluidized bed, specifically, ultra-fine slaked lime
  • the dry powder powder is pneumatically transported into the circulating fluidized bed. Under the action of steam, the temperature of the flue gas can be significantly increased, which coincides with the reaction temperature window of the circulating fluidized bed, and further mixes and reacts with the ultra-fine slaked lime powder powder. Removal of sulfur oxides and fluorides in the flue gas.
  • the solid precipitate formed by absorbing sulfur oxide and fluoride is discharged from the bottom of the circulating fluidized bed.
  • the desulfurization and defluorinating gas with some solid powder is separated in the gas-solid separation device of the circulating fluidized bed, and the gas is directly separated. After being discharged, the separated solid powder returns to the main body of the circulating fluidized bed to absorb sulfur oxides and fluorides again.
  • the concentration of SO 2 in the electrolytic aluminum flue gas is 150-300 mg/Nm 3 , for example, it may be 150 mg/Nm 3 , 180 mg/Nm 3 , 200 mg/Nm 3 , 210 mg/Nm 3 , 240 mg/Nm 3 , 250mg/Nm 3 , 270mg/Nm 3 , 280mg/Nm 3 or 300mg/Nm 3 , but not limited to the listed values, and other unlisted values within the numerical range are also applicable.
  • the concentration of fluoride in the electrolytic aluminum flue gas is 3-8 mg/Nm 3 , for example, 3 mg/Nm 3 , 4 mg/Nm 3 , 5 mg/Nm 3 , 6 mg/Nm 3 , 7 mg/Nm 3 Or 8mg/Nm 3 , but not limited to the listed values, and other unlisted values within the numerical range are also applicable.
  • the residence time of the electrolytic aluminum flue gas in the circulating fluidized bed is 3-8s, for example, it can be 3s, 4s, 5s, 6s, 7s or 8s, but it is not limited to the listed values, which are within the range of values. Other unlisted values are also applicable, and 4-6s can be selected.
  • the flue gas temperature of the electrolytic aluminum flue gas discharged from the circulating fluidized bed is 60-100°C, for example, 60°C, 70°C, 80°C, 90°C, or 100°C, but not limited to the listed values. Other unlisted values in the range also apply, and can be 70-90°C.
  • the particle size D90 of the ground ultrafine dry slaked lime powder powder is 500-1000 mesh, for example, 500 mesh, 600 mesh, 700 mesh, 800 mesh, 900 mesh, or 1000 mesh, but not limited to the listed ones. Values, other unlisted values in the value range are also applicable, and 800-1000 meshes can be selected.
  • the method includes the following steps: under the condition of passing steam, the grinded ultrafine slaked lime dry powder and electrolytic aluminum fume have a particle size D90 of 500-1000 mesh.
  • the gas is subjected to semi-dry desulfurization and defluorination in a circulating fluidized bed to obtain a desulfurized and defluorinated gas at a temperature of 60-100°C; wherein the residence time of electrolytic aluminum flue gas in the circulating fluidized bed is 3-8s.
  • the method described in the present application further includes the step of discharging the obtained desulfurized and defluorinated gas through a chimney.
  • This application uses ground ultrafine slaked lime dry powder powder to perform semi-dry desulfurization and defluorination treatment on electrolytic aluminum flue gas, which greatly reduces the usage of dry slaked lime powder, thereby reducing the temperature drop of electrolytic aluminum flue gas, and overcomes The defect that the flue gas after desulfurization and defluorination treatment blocks the subsequent gas-solid separation device;
  • the electrolytic aluminum flue gas is mixed with steam, and then passed into the circulating fluidized bed for desulfurization and defluorination, which not only can ensure that the temperature of the electrolytic aluminum flue gas does not decrease, but also can improve the electrolytic aluminum flue gas and ultrafine
  • the contact effect of slaked lime powder powder improves the desulfurization and defluorination efficiency.
  • Figure 1 is a schematic structural diagram of a semi-dry desulfurization and defluorination system for electrolytic aluminum flue gas provided in Example 1;
  • Example 2 is a schematic diagram of the structure of the electrolytic aluminum flue gas semi-dry desulfurization and defluorination system provided in Example 2;
  • FIG. 3 is a schematic diagram of the structure of the electrolytic aluminum flue gas semi-dry desulfurization and defluorination system provided by Comparative Example 1.
  • This embodiment provides a semi-dry desulfurization and defluorination system for electrolytic aluminum flue gas.
  • the structure diagram of the semi-dry desulfurization and defluorination system for electrolytic aluminum flue gas is as shown in FIG. Gas delivery unit and desulfurization and defluorination unit.
  • the slaked lime supply unit includes a grinding device 1, the desulfurization and defluorination unit includes a circulating fluidized bed, and the electrolytic aluminum transportation unit includes an electrolytic aluminum flue gas transportation pipeline and a steam transportation pipeline.
  • the grinding device 1 is connected to the slaked lime feed inlet of the circulating fluidized bed; the electrolytic aluminum flue gas delivery pipeline and the steam delivery pipeline are respectively independently connected to the air inlet of the circulating fluidized bed.
  • the grinding device 1 is a grinder; the circulating fluidized bed includes a circulating fluidized bed body 21 and a gas-solid separation device 22, and the gas-solid separation device 22 is a bag filter.
  • the ground ultrafine slaked lime powder and electrolytic aluminum flue gas are semi-dry desulfurization and defluorination in the main body 21 of the circulating fluidized bed.
  • the ultra-fine slaked lime powder is pneumatically conveyed into the main body 21 of the circulating fluidized bed.
  • the temperature of the flue gas can be significantly increased, which is consistent with the reaction temperature window of the circulating fluidized bed, and is further compared with the ultra-fine slaked lime. Dry powder powder is mixed and reacted to remove sulfur oxides and fluorides in the flue gas.
  • the solid slag formed by absorbing sulfur oxides and fluorides is discharged from the bottom of the circulating fluidized bed, and the desulfurization and defluorinating gas with part of solid powder is separated in the gas-solid separation device 22 matched with the circulating fluidized bed. It is directly discharged outside, and the separated solid powder returns to the main body 21 of the circulating fluidized bed to absorb sulfur oxides and fluorides again.
  • This embodiment provides a semi-dry desulfurization and defluorination system for electrolytic aluminum flue gas.
  • the structure diagram of the semi-dry desulfurization and defluorination system for electrolytic aluminum flue gas is as shown in Figure 2, including a hydrated lime batching unit and a hydrated lime supply unit. , Electrolytic aluminum flue gas delivery unit, desulfurization and defluorination unit and flue gas discharge device.
  • the slaked lime batching unit includes a water supply device 3, a quicklime supply device 4, a digestion device 5, and a slaked lime storage device 6.
  • the water supply device 3 and the quicklime supply device 4 are independently connected to the feed inlet of the digestion device 5, and the digestion device 5
  • the outlet of the slaked lime storage device 6 is connected with the inlet of the slaked lime storage device 6, and the outlet of the slaked lime storage device 6 is connected with the inlet of the slaked lime supply.
  • the water supply device 3 includes a water supply storage tank and a matching pump; the quicklime supply device 4 includes a quicklime storage tank and a matching belt conveyor; the digestion device 5 includes a digestion tank; the slaked lime storage device 6 includes a slaked lime storage tank .
  • the water provided by the water supply device 3 and the quicklime provided by the quicklime supply device 4 are mixed in the digestion device 5 to complete the digestion of the quicklime, and the digested slaked lime slurry in the digestion device 5 is transferred to the slaked lime storage under the transportation of the slurry pump Device 6.
  • the slaked lime supply unit includes a grinding device 1, the desulfurization and defluorination unit includes a circulating fluidized bed, and the electrolytic aluminum transportation unit includes an electrolytic aluminum flue gas transportation pipeline and a steam transportation pipeline.
  • the grinding device 1 is connected to the slaked lime feed inlet of the circulating fluidized bed; the electrolytic aluminum flue gas delivery pipe is connected to the steam delivery pipe and then connected to the air inlet of the circulating fluidized bed.
  • the grinding device 1 is a grinder; the circulating fluidized bed includes a circulating fluidized bed body 21 and a gas-solid separation device 22, and the gas-solid separation device 22 is a bag filter.
  • the flue gas discharge device includes an induced draft fan 7 and a chimney 8 that are connected in sequence, and an air inlet of the induced draft fan 7 is connected to an exhaust outlet of the gas-solid separation device 22.
  • the electrolytic aluminum semi-dry desulfurization and defluorination system provided in this embodiment is used for desulfurization and defluorination
  • the water provided by the water supply device 3 and the quicklime provided by the quicklime supply device 4 are mixed in the digestion device 5 to complete the digestion of the quicklime.
  • the digested slaked lime slurry in the digestion device 5 is transferred to the slaked lime storage device 6 under the transportation of the slurry pump.
  • the slaked lime stored in the slaked lime storage device 6 is ground, and is subjected to semi-dry desulfurization and defluorination in the main body 21 of the circulating fluidized bed with electrolytic aluminum flue gas.
  • the ultra-fine slaked lime powder is pneumatically transported into the main body 21 of the circulating fluidized bed. Under the action of steam, the temperature of the flue gas is significantly increased, which is consistent with the reaction temperature window of the circulating fluidized bed, and is further compared with the ultra-fine slaked lime. Dry powder powder is mixed and reacted to remove sulfur oxides and fluorides in the flue gas.
  • the solid slag formed by absorbing sulfur oxides and fluorides is discharged from the bottom of the circulating fluidized bed, and the desulfurization and defluorinating gas with part of solid powder is separated in the gas-solid separation device 22 matched with the circulating fluidized bed. After being introduced into the chimney 8 by the induced draft fan 7, the separated solid powder is returned to the main body 21 of the circulating fluidized bed to absorb sulfur oxides and fluorides again.
  • This comparative example provides a semi-dry desulfurization and defluorination system for electrolytic aluminum flue gas.
  • the schematic structural diagram of the semi-dry desulfurization and defluorination system for electrolytic aluminum flue gas is shown in Figure 3, including a slaked lime supply unit and electrolytic aluminum fume Gas delivery unit and desulfurization and defluorination unit.
  • the slaked lime supply unit in this comparative example is only a slaked lime supply pipe, and the grinding device 1 is not provided, and the rest are the same as in Example 1.
  • the unground slaked lime powder and electrolytic aluminum flue gas are semi-dry desulfurization and defluorination in the main body 21 of the circulating fluidized bed.
  • the dry slaked lime powder is pneumatically conveyed into the main body 21 of the circulating fluidized bed.
  • the electrolytic aluminum flue gas is significantly increased in temperature under the action of steam, which coincides with the reaction temperature window of the circulating fluidized bed, and further mixes and reacts with the dry slaked lime powder. , To remove sulfur oxides and fluorides in the flue gas.
  • the solid slag formed by absorbing sulfur oxides and fluorides is discharged from the bottom of the circulating fluidized bed, and the desulfurization and defluorinating gas with part of solid powder is separated in the gas-solid separation device 22 matched with the circulating fluidized bed. After being introduced into the chimney 8 by the induced draft fan 7, the separated solid powder is returned to the main body 21 of the circulating fluidized bed to absorb sulfur oxides and fluorides again.
  • This application example provides a method for desulfurizing and defluorinating electrolytic aluminum flue gas by applying the electrolytic aluminum flue gas semi-dry desulfurization and defluorination system provided in Example 1.
  • the SO 2 concentration in the electrolytic aluminum flue gas is 190 mg/Nm 3.
  • the fluoride concentration is 5.5 mg/Nm 3 , and the method includes the following steps:
  • the residence time of electrolytic aluminum flue gas in the circulating fluidized bed is 5s.
  • the flue gas analyzer MRU MGA6 uses the flue gas analyzer MRU MGA6 to test the SO 2 concentration in the desulfurization and defluorination gas and the concentration of fluoride.
  • the concentration of SO 2 in the desulfurization and defluorination gas is 11mg/Nm 3
  • the concentration of fluoride is 0.09mg/Nm 3 .
  • This application example provides a method for desulfurizing and defluorinating electrolytic aluminum flue gas by applying the electrolytic aluminum flue gas semi-dry desulfurization and defluorination system provided in Example 1.
  • the SO 2 concentration in the electrolytic aluminum flue gas is 190 mg/Nm 3.
  • the fluoride concentration is 5.5 mg/Nm 3 , and the method includes the following steps:
  • the ultra-fine slaked lime powder powder with a particle size of D90 of 600 mesh and electrolytic aluminum flue gas are subjected to semi-dry desulfurization and defluorination in a circulating fluidized bed to obtain desulfurization and defluorination at a temperature of 70°C.
  • the residence time of electrolytic aluminum flue gas in the circulating fluidized bed is 6s.
  • the flue gas analyzer MRU MGA6 uses the flue gas analyzer MRU MGA6 to test the SO 2 concentration in the desulfurization and defluorination gas and the concentration of fluoride.
  • the concentration of SO 2 in the desulfurization and defluorination gas is 13mg/Nm 3
  • the concentration of fluoride is 0.12mg/Nm 3 .
  • This application example provides a method for desulfurizing and defluorinating electrolytic aluminum flue gas by applying the electrolytic aluminum flue gas semi-dry desulfurization and defluorination system provided in Example 1.
  • the SO 2 concentration in the electrolytic aluminum flue gas is 190 mg/m 3.
  • the fluoride concentration is 5.5 mg/m 3 , and the method includes the following steps:
  • the residence time of electrolytic aluminum flue gas in the circulating fluidized bed is 4s.
  • the flue gas analyzer MRU MGA6 uses the flue gas analyzer MRU MGA6 to test the SO 2 concentration in the desulfurization and defluorination gas and the concentration of fluoride.
  • the concentration of SO 2 in the desulfurization and defluorination gas is 5mg/Nm 3
  • the concentration of fluoride is 0.01mg/Nm 3 .
  • This application example provides a method for desulfurizing and defluorinating electrolytic aluminum flue gas by applying the electrolytic aluminum flue gas semi-dry desulfurization and defluorination system provided in Example 1.
  • the SO 2 concentration in the electrolytic aluminum flue gas is 190 mg/m 3.
  • the fluoride concentration is 5.5 mg/m 3 , and the method includes the following steps:
  • the ultra-fine slaked lime powder powder with a particle size of D90 of 500 mesh and electrolytic aluminum flue gas are subjected to semi-dry desulfurization and defluorination in a circulating fluidized bed to obtain desulfurization and defluorination at a temperature of 60°C.
  • the residence time of electrolytic aluminum flue gas in the circulating fluidized bed is 8s.
  • the flue gas analyzer MRU MGA6 uses the flue gas analyzer MRU MGA6 to test the concentration of SO 2 in the desulfurization and defluorination gas and the concentration of fluoride.
  • the concentration of SO 2 in the desulfurization and defluorination gas is 16mg/Nm 3
  • the concentration of fluoride is 0.15mg/Nm 3 .
  • This application example provides a method for desulfurizing and defluorinating electrolytic aluminum flue gas by applying the electrolytic aluminum flue gas semi-dry desulfurization and defluorination system provided in Example 1.
  • the SO 2 concentration in the electrolytic aluminum flue gas is 190 mg/m 3.
  • the fluoride concentration is 5.5 mg/m 3 , and the method includes the following steps:
  • the residence time of electrolytic aluminum flue gas in the circulating fluidized bed is 3s.
  • the flue gas analyzer MRU MGA6 uses the flue gas analyzer MRU MGA6 to test the concentration of SO 2 in the desulfurization and defluorination gas and the concentration of fluoride.
  • the concentration of SO 2 in the desulfurization and defluorination gas is 6mg/Nm 3
  • the concentration of fluoride is 0.02mg/Nm 3 .
  • This application example provides a method for desulfurizing and defluorinating electrolytic aluminum flue gas using the electrolytic aluminum flue gas semi-dry desulfurization and defluorination system provided in Example 2.
  • the SO 2 concentration in the electrolytic aluminum flue gas is 190 mg/Nm 3.
  • the fluoride concentration is 5.5 mg/Nm 3 , and the method includes the following steps:
  • the residence time of electrolytic aluminum flue gas in the circulating fluidized bed is 5s.
  • the flue gas analyzer MRU MGA6 uses the flue gas analyzer MRU MGA6 to test the SO 2 concentration in the desulfurization and defluorination gas and the concentration of fluoride.
  • the concentration of SO 2 in the desulfurization and defluorination gas is 11mg/Nm 3
  • the concentration of fluoride is 0.09mg/Nm 3 .
  • This comparative application example provides a method for desulfurizing and defluorinating electrolytic aluminum flue gas using the electrolytic aluminum flue gas semi-dry desulfurization and defluorination system provided in Comparative Example 1.
  • the SO 2 concentration in the electrolytic aluminum flue gas is 190 mg/ Nm 3
  • the fluoride concentration is 5.5 mg/Nm 3
  • the method includes the following steps:
  • the unground slaked lime powder and electrolytic aluminum flue gas are subjected to semi-dry desulfurization and defluorination in a circulating fluidized bed to obtain desulfurization and defluorination gas at a temperature of 80°C; among them, electrolytic aluminum flue gas
  • the residence time of gas in the circulating fluidized bed is 5s.
  • the concentration of the fluorine gas desulfurization and SO 2 was 32mg / Nm 3, the concentration of fluoride was 0.53mg / Nm 3 .
  • the particle size of the dry slaked lime powder is relatively large, and it cannot effectively absorb SO 2 and fluoride when the amount of the dry slaked lime powder is small.
  • this application uses the ground ultrafine dry slaked lime powder to perform semi-dry desulfurization and defluorination treatment on electrolytic aluminum flue gas, which greatly reduces the amount of dry slaked lime powder used, thereby reducing the temperature drop of the electrolytic aluminum flue gas.
  • this application mixes the electrolytic aluminum flue gas with steam and then passes it into the circulating fluidized bed for desulfurization and defluorination, which can not only ensure the electrolysis
  • the temperature of the aluminum flue gas does not decrease, and the contact effect between the electrolytic aluminum flue gas and the ultra-fine slaked lime powder powder is improved, and the desulfurization and defluorination efficiency is improved, so that the SO 2 concentration in the desulfurization and defluorination gas is as low as 5 mg/Nm 3 .
  • the concentration of the compound is as low as 0.01 mg/Nm 3 .

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Abstract

提供一种电解铝烟气半干法脱硫脱氟系统及方法，所述系统包括消石灰供料单元、电解铝烟气输送单元与脱硫脱氟单元；消石灰供料单元包括研磨装置（1），脱硫脱氟单元包括循环流化床，电解铝输送单元包括电解铝烟气输送管道以及蒸汽输送管道；研磨装置（1）与循环流化床的消石灰供料入口连接；电解铝烟气输送管道与蒸汽输送管道与循环流化床的进气口连接。

Description

一种电解铝烟气半干法脱硫脱氟系统及方法 技术领域
本申请属于工业废气治理领域，涉及一种脱硫脱氟系统及方法，例如涉及一种电解铝烟气半干法脱硫脱氟系统及方法。
背景技术
随着科技的不断进步，铝电解工艺日趋成熟，全世界原铝的产量有了大幅度的增长。但是同时铝材也是生产过程中环境污染最大的金属材料之一。铝电解生产过程中散发有害气体(氟化氢和二氧化硫)以及粉尘(含氟粉尘、氧化铝和碳粉)等有害物质，如果这些废弃物得不到有效处理，将产生严重的环境和生态问题，因此，铝工业产生的环境问题一直受到人们的广泛关注。
铝电解生产每吨铝排氟约为15-40kg/t-Al，二氧化硫4-16kg/t-Al，为降低烟气中污染物的排放浓度，因此，在常规的电解铝生产工艺中，铝电解槽烟气治理方法包括湿法净化与干法净化两种方法。
所述干法净化是利用设置于电解槽上部的集气罩捕集烟气进入净化设施，在净化设施中利用电解原料氧化铝吸附烟气中的氟化氢，再通过布袋除尘器实现气固分离，达到净化烟气，同时去除气态氟和固态氟的目的，吸附氟之后的氧化铝作为电解生产的原料返回电解槽使用，氧化铝吸附的氟回补了电解过程所需要的氟化盐电解质。
例如，CN 208055476 U公开了一种电解铝烟气除氟化物干法净化装置，包括烟气进管，所述烟气进管的一端贯通连接于第一抽风机的进风口处，第一抽风机的出风口处通过连接管连接于反应罐的左侧壁，反应罐的外表面固定套接有第一齿轮，反应罐安装在支架上，支架上安装有电机，电机的主轴端固定连 接有第二齿轮，反应罐的上端面镶嵌有氧化铝料罐，氧化铝料罐的底部安装有出料管，出料管的底端贯穿反应罐的顶壁位于反应罐的内部，且出料管上安装有电磁阀，反应罐的左侧壁安装有电动推杆，电动推杆的活塞杆顶端位于反应罐内且端头处固定连接与存料管的左侧壁。
氧化铝电解烟气经上述净化装置处理后，烟气中二氧化硫的浓度仍能够达到150-300mg/Nm 3且氟化物的浓度为2-6mg/Nm 3，无法达到国家超低排放标准。且上述净化装置仅能对氧化铝烟气中的氟化物和粉尘进行处理，对二氧化硫没有净化效果。
CN 208130773 U公开了一种高效率节能电解铝烟气脱硫装置，包括电解铝烟气干法系统，所述电解铝烟气脱硫装置通过风机将电解铝干法系统处理后的烟气通入设置有水的箱体内，通过水对电解铝干法处理后的烟气中的SO 2进行吸收。
CN 107233793 A公开了一种电解铝烟气脱硫装置及脱硫方法，该方法将电解铝烟气干法系统出来的烟气与流态化沸腾箱体连接，流态化沸腾箱体出来的烟气再通过烟囱排出。
CN 109589750 A公开了一种铝电解烟气的经济型脱硫、去氟工艺，所述工艺利用经干法净化系统处理后的电解烟气具有污染物含量低的特点，一般SO 2<300mg/Nm 3，HF<3mg/Nm 3，在干法烟气净化系统后建设喷淋塔，电解铝烟气在喷淋塔内经过水的再次洗涤，SO 2、HF与水融合，使烟气中的污染物进一步脱除，实现了烟气中SO 2≤35mg/Nm 3、HF≤0.3mg/Nm 3的超低排放指标。
然而CN 208130773 U、CN 107233793 A以及CN 109589750 A公开的技术方案均为添加脱硫装置进行脱硫，提高了脱硫成本，不利于工业化推广。
湿法电解铝烟气净化方法主要为石灰石膏法，该方法存在着水的二次污染和设备腐蚀问题。例如CN 109224827 A公开了一种电解铝生产系统烟气趋零排放湿法脱硫系统，包括石灰石浆料供浆系统、烟气系统、SO 2吸收系统和石膏脱水系统。该系统能够减少电解铝生产过程中排放的氟化氢、沥青胶油、颗粒物以及二氧化硫等污染物，但由于湿法脱硫必定会带来电解铝烟气的降温，而过低的烟气温度容易造成硫酸钙等物质对管道以及后续生产设备的腐蚀，不利于持续生产。
因此，提供一种效率高、无二次污染、操作简单、能够同时去除氟化物与硫氧化物的电解铝烟气半干法脱硫脱氟系统及方法，对于降低电解铝烟气对环境的污染以及提高企业的经济效益具有重要的意义。
发明内容
以下是对本文详细描述的主题的概述。本概述并非是为了限制权利要求的保护范围。
本申请的目的在于提供一种电解铝烟气半干法脱硫脱氟系统及方法，所述电解铝烟气半干法脱硫脱氟系统通过对消石灰进行研磨，大大降低了消石灰干粉粉末粒径，使用较少的超细消石灰干粉粉末即可完成脱硫脱氟处理；通过蒸汽与超细消石灰干粉粉末的添加，降低了电解铝烟气的温降，且蒸汽的添加进一步提高了电解铝烟气的温度，不仅使烟气温度符合循环流化床反应温度窗口，而且克服了降温后电解铝烟气堵塞气固分离装置的缺陷。
为达到此申请目的，本申请采用以下技术方案：
第一方面，本申请提供了一种电解铝烟气半干法脱硫脱氟系统，所述电解铝烟气半干法脱硫脱氟系统包括消石灰供料单元、电解铝烟气输送单元以及脱 硫脱氟单元。
所述消石灰供料单元包括研磨装置，所述脱硫脱氟单元包括循环流化床，所述电解铝输送单元包括电解铝烟气输送管道以及蒸汽输送管道。
所述研磨装置与循环流化床的消石灰供料入口连接；所述电解铝烟气输送管道与蒸汽输送管道与循环流化床的进气口连接。
本申请所述电解铝烟气输送管道与蒸汽输送管道与循环流化床的进气口连接的连接方式包括：电解铝烟气输送管道与蒸汽输送管道分别独立地与循环流化床的进气口连接或电解铝烟气输送管道与蒸汽输送管道连接后，再与循环流化床的进气口连接。
本申请通过对消石灰进行研磨，大大降低了消石灰干粉粉末粒径，使用较少的超细消石灰干粉粉末即可完成脱硫脱氟处理；通过蒸汽与超细消石灰干粉粉末的添加，降低了电解铝烟气的温降，且蒸汽的添加进一步提高了电解铝烟气的温度，不仅使烟气温度符合循环流化床反应温度窗口，而且克服了降温后电解铝烟气堵塞气固分离装置的缺陷。
可选地，所述研磨装置包括研磨机和/或球磨机。
本申请所述研磨机和/或球磨机为本领域常用的研磨机和/或球磨机，本领域技术人员可根据对消石灰干粉粉末粒径的要求，选择合适参数的研磨装置。
可选地，所述循环流化床的气固分离装置包括布袋除尘器和/或旋风分离器，可选为布袋除尘器。
布袋除尘器具有较高的捕集效率，对于20μm以下的粒子的捕集效率可达99％以上。布袋除尘器主要由滤袋、袋架和壳体组成，壳体由箱体和净气室组成，布袋安装在箱体与净气室中间的隔板上。含尘气体进入箱体后，粉体产生惯性、 扩散、粘附、静电作用附着在滤布表面，清洁气体穿过滤布的孔隙从净气室排出，滤布上的粉尘通过反吹或振击作用脱离滤布而堕入料斗中。
若经半干法处理的电解铝烟气的温度较低，则容易使电解铝烟气中夹带的硫酸钙和/或亚硫酸钙沉积在滤布上，从而影响布袋除尘器的除尘效率。本申请通过对消石灰进行研磨，大大降低了消石灰干粉粉末粒径，使用较少的超细消石灰干粉粉末即可完成脱硫脱氟处理；通过蒸汽与超细消石灰干粉粉末的添加，降低了电解铝烟气的温降，且蒸汽的添加进一步提高了电解铝烟气的温度，不仅使烟气温度符合循环流化床反应温度窗口，而且克服了降温后电解铝烟气堵塞气固分离装置的缺陷。
可选地，所述电解铝烟气半干法脱硫脱氟系统还包括设置于消石灰供料单元之前的消石灰配料单元。
可选地，所述消石灰配料单元包括供水装置、生石灰供给装置、消化装置以及消石灰存储装置，所述供水装置与生石灰供给装置分别独立地与消化装置的进料口连接，消化装置的出料口与消石灰存储装置的进料口连接，消石灰存储装置的出料口与消石灰供料入口连接。
由供水装置提供的水与生石灰供给装置提供的生石灰在消化装置内混合，从而完成生石灰的消化，在消化装置内完成消化的消石灰在本领域常规浆料输送装置的作用下转移至消石灰存储装置。
本申请所述供水装置、生石灰供给装置、消化装置以及消石灰存储装置均为本领域技术人员常用的供水装置、生石灰供给装置、消化装置以及消石灰存储装置。例如，所述供水装置包括但不限于供水储罐以及配套的泵；所述生石灰供给装置包括但不限于生石灰储罐以及配套的皮带传送装置；所述消化装置 包括但不限于消化罐；所述消石灰存储装置包括但不限于消石灰储罐。
可选地，所述电解铝烟气半干法脱硫脱氟系统还包括设置于气固分离装置后的烟气排放装置。
经过半干法脱硫脱氟系统后的电解铝烟气中的SO 2含量以及氟化物含量较低，可经过烟气排放装置直接排放。
可选地，所述烟气排放装置包括依次连接的引风机与烟囱，所述引风机的引风口与气固分离装置的排气口连接。
经过半干法脱硫脱氟系统处理后的电解铝烟气经引风机排入烟囱，并从烟囱外排。
第二方面，本申请提供了一种应用如第一方面所述的电解铝烟气半干法脱硫脱氟系统进行脱硫脱氟的方法，所述方法包括如下步骤：在通入蒸汽的条件下，使研磨后的超细消石灰干粉粉末与电解铝烟气在循环流化床内进行半干法脱硫脱氟，得到脱硫脱氟气。
本申请所述超细消石灰干粉为粒径D90为500-1000目的消石灰干粉，超细消石灰干粉粉末与电解铝烟气在循环流化床内进行半干法脱硫脱氟，具体地，超细消石灰干粉粉末由气力输送到循环流化床内，电解铝烟气在蒸汽的作用下，烟气温度得以明显提升，与循环流化床反应温度窗口相吻合，进一步与超细消石灰干粉粉末混合反应，去除烟气中的硫氧化物以及氟化物。
吸收硫氧化物以及氟化物形成的固体沉淀由循环流化床的底部外排，夹带有部分固体粉末的脱硫脱氟气在循环流化床配套的气固分离装置内进行气固分离，气体直接进行外排，分离后的固体粉末返回循环流化床主体再次对硫氧化物以及氟化物进行吸收。
可选地，所述电解铝烟气中SO 2的浓度为150-300mg/Nm 3，例如可以是150mg/Nm 3、180mg/Nm 3、200mg/Nm 3、210mg/Nm 3、240mg/Nm 3、250mg/Nm 3、270mg/Nm 3、280mg/Nm 3或300mg/Nm 3，但不限于所列举的数值，数值范围内其它未列举的数值同样适用。
可选地，所述电解铝烟气中氟化物的浓度为3-8mg/Nm 3，例如可以是3mg/Nm 3、4mg/Nm 3、5mg/Nm 3、6mg/Nm 3、7mg/Nm 3或8mg/Nm 3，但不限于所列举的数值，数值范围内其它未列举的数值同样适用。
可选地，所述电解铝烟气在循环流化床内的停留时间为3-8s，例如可以是3s、4s、5s、6s、7s或8s，但不限于所列举的数值，数值范围内其它未列举的数值同样适用，可选为4-6s。
可选地，电解铝烟气排出循环流化床的烟气温度为60-100℃，例如可以是60℃、70℃、80℃、90℃或100℃，但不限于所列举的数值，数值范围内其它未列举的数值同样适用，可选为70-90℃。
可选地，所述研磨后的超细消石灰干粉粉末粒径D90为500-1000目，例如可以是500目、600目、700目、800目、900目或1000目，但不限于所列举的数值，数值范围内其它未列举的数值同样适用，可选为800-1000目。
作为本申请第二方面所述方法的可选技术方案，所述方法包括如下步骤：通入蒸汽的条件下，使研磨后的粒径D90为500-1000目的超细消石灰干粉粉末与电解铝烟气在循环流化床内进行半干法脱硫脱氟，得到温度为60-100℃的脱硫脱氟气；其中，电解铝烟气在循环流化床内的停留时间为3-8s。
进一步可选地，本申请所述方法还包括将得到的脱硫脱氟气经过烟囱外排的步骤。
相对于相关技术，本申请具有以下有益效果：
(1)本申请利用经过研磨的超细消石灰干粉粉末对电解铝烟气进行半干法脱硫脱氟处理，大大降低了消石灰干粉的使用量，从而降低了电解铝烟气的温降情况，克服了经过脱硫脱氟处理后的烟气堵塞后续气固分离装置的缺陷；
(2)本申请通过将电解铝烟气与蒸汽混合，然后再通入循环流化床进行脱硫脱氟，不仅能够保证电解铝烟气温度不发生降低，还能够提高电解铝烟气与超细消石灰干粉粉末的接触效果，提高了脱硫脱氟效率。
在阅读并理解了详细描述和附图后，可以明白其他方面。
附图说明
图1为实施例1提供的电解铝烟气半干法脱硫脱氟系统的结构示意图；
图2为实施例2提供的电解铝烟气半干法脱硫脱氟系统的结构示意图；
图3为对比例1提供的电解铝烟气半干法脱硫脱氟系统的结构示意图。
其中：1，研磨装置；21，循环流化床主体；22，气固分离装置；3，供水装置；4，生石灰供给装置；5，消化装置；6，消石灰存储装置；7，引风机；8烟囱。
具体实施方式
下面通过具体实施方式来进一步说明本申请的技术方案。本领域技术人员应该明了，所述实施例仅仅是帮助理解本申请，不应视为对本申请的具体限制。
实施例1
本实施例提供了一种电解铝烟气半干法脱硫脱氟系统，所述电解铝烟气半干法脱硫脱氟系统的结构示意图如图1所述，包括消石灰供料单元、电解铝烟气输送单元以及脱硫脱氟单元。
所述消石灰供料单元包括研磨装置1，所述脱硫脱氟单元包括循环流化床，所述电解铝输送单元包括电解铝烟气输送管道以及蒸汽输送管道。
所述研磨装置1与循环流化床的消石灰供料入口连接；所述电解铝烟气输送管道与蒸汽输送管道分别独立地与循环流化床的进气口连接。
所述研磨装置1为研磨机；所述循环流化床包括循环流化床主体21以及气固分离装置22，所述气固分离装置22为布袋除尘器。
应用本实施例提供的电解铝半干法脱硫脱氟系统进行脱硫脱氟时，经过研磨的超细消石灰干粉粉末与电解铝烟气在循环流化床主体21内进行半干法脱硫脱氟。超细消石灰干粉粉末由气力输送到循环流化床主体21内，电解铝烟气在蒸汽的作用下，烟气温度得以明显提升，与循环流化床反应温度窗口相吻合，进一步与超细消石灰干粉粉末混合反应，去除烟气中的硫氧化物以及氟化物。
吸收硫氧化物以及氟化物形成的固渣由循环流化床的底部外排，夹带有部分固体粉末的脱硫脱氟气在循环流化床配套的气固分离装置22内进行气固分离，气体直接进行外排，分离后的固体粉末返回循环流化床主体21再次对硫氧化物以及氟化物进行吸收。
实施例2
本实施例提供了一种电解铝烟气半干法脱硫脱氟系统，所述电解铝烟气半干法脱硫脱氟系统的结构示意图如图2所述，包括消石灰配料单元、消石灰供料单元、电解铝烟气输送单元、脱硫脱氟单元以及烟气排放装置。
所述消石灰配料单元包括供水装置3、生石灰供给装置4、消化装置5以及消石灰存储装置6，所述供水装置3与生石灰供给装置4分别独立地与消化装置5的进料口连接，消化装置5的出料口与消石灰存储装置6的进料口连接，消石 灰存储装置6的出料口与消石灰供料入口连接。
所述供水装置3包括供水储罐以及配套的泵；所述生石灰供给装置4包括生石灰储罐以及配套的皮带传送装置；所述消化装置5包括消化罐；所述消石灰存储装置6包括消石灰储罐。
由供水装置3提供的水与生石灰供给装置4提供的生石灰在消化装置5内混合，从而完成生石灰的消化，在消化装置5内完成消化的消石灰浆料在浆料泵的输送下转移至消石灰存储装置6。
所述消石灰供料单元包括研磨装置1，所述脱硫脱氟单元包括循环流化床，所述电解铝输送单元包括电解铝烟气输送管道以及蒸汽输送管道。
所述研磨装置1与循环流化床的消石灰供料入口连接；所述电解铝烟气输送管道与蒸汽输送管道连接后再与循环流化床的进气口连接。
所述研磨装置1为研磨机；所述循环流化床包括循环流化床主体21以及气固分离装置22，所述气固分离装置22为布袋除尘器。
所述烟气排放装置包括依次连接的引风机7与烟囱8，所述引风机7的引风口与气固分离装置22的排气口连接。
应用本实施例提供的电解铝半干法脱硫脱氟系统进行脱硫脱氟时，由供水装置3提供的水与生石灰供给装置4提供的生石灰在消化装置5内混合，从而完成生石灰的消化，在消化装置5内完成消化的消石灰浆料在浆料泵的输送下转移至消石灰存储装置6。
然后，存储在消石灰存储装置6内的消石灰经过研磨后，与电解铝烟气在循环流化床主体21内进行半干法脱硫脱氟。超细消石灰干粉粉末由气力输送到循环流化床主体21内，电解铝烟气在蒸汽的作用下，烟气温度得以明显提升， 与循环流化床反应温度窗口相吻合，进一步与超细消石灰干粉粉末混合反应，去除烟气中的硫氧化物以及氟化物。
吸收硫氧化物以及氟化物形成的固渣由循环流化床的底部外排，夹带有部分固体粉末的脱硫脱氟气在循环流化床配套的气固分离装置22内进行气固分离，气体由引风机7引入烟囱8后进行外排，分离后的固体粉末返回循环流化床主体21再次对硫氧化物以及氟化物进行吸收。
对比例1
本对比例提供了一种电解铝烟气半干法脱硫脱氟系统，所述电解铝烟气半干法脱硫脱氟系统的结构示意图如图3所述，包括消石灰供料单元、电解铝烟气输送单元以及脱硫脱氟单元。
与实施例1相比，本对比例所述消石灰供料单元仅为消石灰供料管道，并没有设置研磨装置1，其余均与实施例1相同。
应用本对比例提供的电解铝半干法脱硫脱氟系统进行脱硫脱氟时，未经过研磨的消石灰干粉粉末与电解铝烟气在循环流化床主体21内进行半干法脱硫脱氟。消石灰干粉粉末由气力输送到循环流化床主体21内，电解铝烟气在蒸汽的作用下，烟气温度得以明显提升，与循环流化床反应温度窗口相吻合，进一步与消石灰干粉粉末混合反应，去除烟气中的硫氧化物以及氟化物。
吸收硫氧化物以及氟化物形成的固渣由循环流化床的底部外排，夹带有部分固体粉末的脱硫脱氟气在循环流化床配套的气固分离装置22内进行气固分离，气体由引风机7引入烟囱8后进行外排，分离后的固体粉末返回循环流化床主体21再次对硫氧化物以及氟化物进行吸收。
应用例1
本应用例提供了一种应用实施例1提供的电解铝烟气半干法脱硫脱氟系统对电解铝烟气进行脱硫脱氟的方法，所述电解铝烟气中SO 2浓度为190mg/Nm 3，氟化物浓度为5.5mg/Nm 3，所述方法包括如下步骤：
通入蒸汽的条件下，使研磨后的粒径D90为700目的超细消石灰干粉粉末与电解铝烟气在循环流化床内进行半干法脱硫脱氟，得到温度为80℃的脱硫脱氟气；其中，电解铝烟气在循环流化床内的停留时间为5s。
使用烟气分析仪MRU MGA6对脱硫脱氟气中的SO 2浓度以及氟化物的浓度进行测试，脱硫脱氟气中SO 2的浓度为11mg/Nm 3，氟化物的浓度为0.09mg/Nm 3。
应用例2
本应用例提供了一种应用实施例1提供的电解铝烟气半干法脱硫脱氟系统对电解铝烟气进行脱硫脱氟的方法，所述电解铝烟气中SO 2浓度为190mg/Nm 3，氟化物浓度为5.5mg/Nm 3，所述方法包括如下步骤：
通入蒸汽的条件下，使研磨后的粒径D90为600目的超细消石灰干粉粉末与电解铝烟气在循环流化床内进行半干法脱硫脱氟，得到温度为70℃的脱硫脱氟气；其中，电解铝烟气在循环流化床内的停留时间为6s。
使用烟气分析仪MRU MGA6对脱硫脱氟气中的SO 2浓度以及氟化物的浓度进行测试，脱硫脱氟气中SO 2的浓度为13mg/Nm 3，氟化物的浓度为0.12mg/Nm 3。
应用例3
本应用例提供了一种应用实施例1提供的电解铝烟气半干法脱硫脱氟系统对电解铝烟气进行脱硫脱氟的方法，所述电解铝烟气中SO 2浓度为190mg/m 3，氟化物浓度为5.5mg/m 3，所述方法包括如下步骤：
通入蒸汽的条件下，使研磨后的粒径D90为800目的超细消石灰干粉粉末 与电解铝烟气在循环流化床内进行半干法脱硫脱氟，得到温度为90℃的脱硫脱氟气；其中，电解铝烟气在循环流化床内的停留时间为4s。
使用烟气分析仪MRU MGA6对脱硫脱氟气中的SO 2浓度以及氟化物的浓度进行测试，脱硫脱氟气中SO 2的浓度为5mg/Nm 3，氟化物的浓度为0.01mg/Nm 3。
应用例4
本应用例提供了一种应用实施例1提供的电解铝烟气半干法脱硫脱氟系统对电解铝烟气进行脱硫脱氟的方法，所述电解铝烟气中SO 2浓度为190mg/m 3，氟化物浓度为5.5mg/m 3，所述方法包括如下步骤：
通入蒸汽的条件下，使研磨后的粒径D90为500目的超细消石灰干粉粉末与电解铝烟气在循环流化床内进行半干法脱硫脱氟，得到温度为60℃的脱硫脱氟气；其中，电解铝烟气在循环流化床内的停留时间为8s。
使用烟气分析仪MRU MGA6对脱硫脱氟气中的SO 2浓度以及氟化物的浓度进行测试，脱硫脱氟气中SO 2的浓度为16mg/Nm 3，氟化物的浓度为0.15mg/Nm 3。
应用例5
本应用例提供了一种应用实施例1提供的电解铝烟气半干法脱硫脱氟系统对电解铝烟气进行脱硫脱氟的方法，所述电解铝烟气中SO 2浓度为190mg/m 3，氟化物浓度为5.5mg/m 3，所述方法包括如下步骤：
通入蒸汽的条件下，使研磨后的粒径D90为1000目的超细消石灰干粉粉末与电解铝烟气在循环流化床内进行半干法脱硫脱氟，得到温度为100℃的脱硫脱氟气；其中，电解铝烟气在循环流化床内的停留时间为3s。
使用烟气分析仪MRU MGA6对脱硫脱氟气中的SO 2浓度以及氟化物的浓度进行测试，脱硫脱氟气中SO 2的浓度为6mg/Nm 3，氟化物的浓度为0.02mg/Nm 3。
应用例6
本应用例提供了一种应用实施例2提供的电解铝烟气半干法脱硫脱氟系统对电解铝烟气进行脱硫脱氟的方法，所述电解铝烟气中SO 2浓度为190mg/Nm 3，氟化物浓度为5.5mg/Nm 3，所述方法包括如下步骤：
通入蒸汽的条件下，使研磨后的粒径D90为700目的超细消石灰干粉粉末与电解铝烟气在循环流化床内进行半干法脱硫脱氟，得到温度为80℃的脱硫脱氟气；其中，电解铝烟气在循环流化床内的停留时间为5s。
使用烟气分析仪MRU MGA6对脱硫脱氟气中的SO 2浓度以及氟化物的浓度进行测试，脱硫脱氟气中SO 2的浓度为11mg/Nm 3，氟化物的浓度为0.09mg/Nm 3。
对比应用例1
本对比应用例提供了一种应用对比例1提供的电解铝烟气半干法脱硫脱氟系统对电解铝烟气进行脱硫脱氟的方法，所述电解铝烟气中SO 2浓度为190mg/Nm 3，氟化物浓度为5.5mg/Nm 3，所述方法包括如下步骤：
通入蒸汽的条件下，使未经研磨的消石灰干粉粉末与电解铝烟气在循环流化床内进行半干法脱硫脱氟，得到温度为80℃的脱硫脱氟气；其中，电解铝烟气在循环流化床内的停留时间为5s。
使用烟气分析仪MRU MGA6对脱硫脱氟气中的SO 2浓度以及氟化物的浓度进行测试，脱硫脱氟气中SO 2的浓度为32mg/Nm 3，氟化物的浓度为0.53mg/Nm 3。
由于消石灰干粉粉末未经过研磨，消石灰干粉粉末粒径较大，在消石灰干粉用量较小的情况下无法对SO 2以及氟化物进行有效吸收。
综上所述，本申请利用经过研磨的超细消石灰干粉粉末对电解铝烟气进行半干法脱硫脱氟处理，大大降低了消石灰干粉的使用量，从而降低了电解铝烟 气的温降情况，克服了经过脱硫脱氟处理后的烟气堵塞后续气固分离装置的缺陷；本申请通过将电解铝烟气与蒸汽混合，然后再通入循环流化床进行脱硫脱氟，不仅能够保证电解铝烟气温度不发生降低，还能够提高电解铝烟气与超细消石灰干粉粉末的接触效果，提高了脱硫脱氟效率，使脱硫脱氟气中SO 2的浓度低至5mg/Nm 3，氟化物的浓度低至0.01mg/Nm 3。
申请人声明，以上所述仅为本申请的具体实施方式，但本申请的保护范围并不局限于此。

Claims (11)

  1. 一种电解铝烟气半干法脱硫脱氟系统，其中，所述电解铝烟气半干法脱硫脱氟系统包括消石灰供料单元、电解铝烟气输送单元以及脱硫脱氟单元；
    所述消石灰供料单元包括研磨装置，所述脱硫脱氟单元包括循环流化床，所述电解铝输送单元包括电解铝烟气输送管道以及蒸汽输送管道；
    所述研磨装置与循环流化床的消石灰供料入口连接；所述电解铝烟气输送管道与蒸汽输送管道与循环流化床的进气口连接。
  2. 根据权利要求1所述的电解铝烟气半干法脱硫脱氟系统，其中，所述研磨装置包括研磨机和/或球磨机。
  3. 根据权利要求1或2所述的电解铝烟气半干法脱硫脱氟系统，其中，所述循环流化床的气固分离装置包括布袋除尘器和/或旋风分离器，可选为布袋除尘器。
  4. 根据权利要求1-3任一项所述的电解铝烟气半干法脱硫脱氟系统，其中，所述电解铝烟气半干法脱硫脱氟系统还包括设置于消石灰供料单元之前的消石灰配料单元；
    可选地，所述消石灰配料单元包括供水装置、生石灰供给装置、消化装置以及消石灰存储装置，所述供水装置与生石灰供给装置分别独立地与消化装置的进料口连接，消化装置的出料口与消石灰存储装置的进料口连接，消石灰存储装置的出料口与消石灰供料入口连接。
  5. 根据权利要求3所述的电解铝烟气半干法脱硫脱氟系统，其中，所述电解铝烟气半干法脱硫脱氟系统还包括设置于气固分离装置后的烟气排放装置。
  6. 根据权利要求5所述的电解铝烟气半干法脱硫脱氟系统，其中，所述烟气排放装置包括依次连接的引风机与烟囱，所述引风机的引风口与气固分离装 置的排气口连接。
  7. 一种应用如权利要求1-6任一项所述的电解铝烟气半干法脱硫脱氟系统进行脱硫脱氟的方法，其中，所述方法包括如下步骤：在通入蒸汽的条件下，使研磨后的超细消石灰干粉粉末与电解铝烟气在循环流化床内进行半干法脱硫脱氟，得到脱硫脱氟气。
  8. 根据权利要求7所述的方法，其中，所述电解铝烟气排出循环流化床的温度为60-100℃，可选为70-90℃。
  9. 根据权利要求7或8所述的方法，其中，所述研磨后的超细消石灰干粉粉末粒径D90为500-1000目，可选为800-1000目。
  10. 根据权利要求7-9任一项所述的方法，其中，所述电解铝烟气在循环流化床内的停留时间为3-8s，可选为4-6s。
  11. 根据权利要求7-10任一项所述的方法，其中，所述方法包括如下步骤：通入蒸汽的条件下，使研磨后的粒径D90为500-1000目的超细消石灰干粉粉末与电解铝烟气在循环流化床内进行半干法脱硫脱氟，得到温度为60-100℃的脱硫脱氟气；其中，电解铝烟气在循环流化床内的停留时间为3-8s。
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