WO2014194564A1 - 用于从窑法磷酸工艺水化吸磷后的烟气中回收氟的设备及工艺 - Google Patents

用于从窑法磷酸工艺水化吸磷后的烟气中回收氟的设备及工艺 Download PDF

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Publication number
WO2014194564A1
WO2014194564A1 PCT/CN2013/081135 CN2013081135W WO2014194564A1 WO 2014194564 A1 WO2014194564 A1 WO 2014194564A1 CN 2013081135 W CN2013081135 W CN 2013081135W WO 2014194564 A1 WO2014194564 A1 WO 2014194564A1
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acid
tower
liquid
flue gas
fluorosilicic
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PCT/CN2013/081135
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English (en)
French (fr)
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侯拥和
魏世发
魏琛娟
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四川玖长科技有限公司
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Priority to RU2015144555A priority Critical patent/RU2638982C2/ru
Publication of WO2014194564A1 publication Critical patent/WO2014194564A1/zh
Priority to US14/958,811 priority patent/US10232312B2/en

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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
    • B01D53/68—Halogens or halogen compounds
    • 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
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/77—Liquid phase processes
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/19—Fluorine; Hydrogen fluoride
    • C01B7/20—Fluorine
    • 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
    • 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
    • B01D2257/206—Organic halogen compounds
    • B01D2257/2066—Fluorine
    • 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
    • B01D53/14—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 by absorption
    • B01D53/1406—Multiple stage absorption
    • 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
    • B01D53/14—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 by absorption
    • B01D53/1456—Removing acid components
    • 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
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/77—Liquid phase processes
    • B01D53/78—Liquid phase processes with gas-liquid contact
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/18—Phosphoric acid
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Definitions

  • the present invention relates to an apparatus and a process for recovering fluorine-containing substances from flue gas, and more particularly to an apparatus and process for recovering fluorine from flue gas after hydration and phosphorus absorption by a kiln process phosphoric acid process (KPA).
  • KPA kiln process phosphoric acid process
  • wet process phosphoric acid that is, the phosphate ore is decomposed by sulfuric acid to obtain dilute phosphoric acid and solid waste residue (referred to as phosphogypsum) mainly composed of CaS0 4 ⁇ ⁇ 3 ⁇ 40, and the dilute phosphoric acid is concentrated to obtain wet-process phosphoric acid containing about 54% of phosphoric acid.
  • the main disadvantages of this process are as follows: First, a large amount of sulfuric acid is consumed; second, the waste slag phosphogypsum cannot be effectively utilized, and the entrained sulfuric acid, phosphoric acid and soluble fluoride are all dissolved in water, and are naturally washed by rainwater, which is easy to wash. Serious pollution to the environment; Third, the product phosphoric acid has a high impurity content, generally only used to produce fertilizer; Fourth, in order to ensure the economical efficiency of the product, high-grade phosphate rock must be used.
  • the product yellow phosphorus is obtained, and the exhaust gas containing CO is ignited and burned at the outlet of the chimney, and is discharged into the atmosphere; the obtained heating is heated to about 80 ° C, and it is changed into a liquid phase, which is generated in the hydration tower and the introduced air.
  • the oxidative combustion reaction is carried out to obtain phosphoric anhydride P 2 0 5 , which is then absorbed by water to obtain phosphoric acid.
  • thermal process phosphoric acid consumes a lot of electric energy; Second, the gas separated from P 4 after being discharged from the submerged arc furnace is also entrained with a large amount of fluoride (presented by SiF ⁇ P HF) and a small amount of unprecipitated gas P. 4 , this will cause serious pollution to the atmospheric environment; Third, the gas containing a large amount of CO is directly burned and emptied, and energy is wasted; Fourth, in order to ensure the economical efficiency of production, high-grade phosphate ore is also required.
  • the method is to finely grind phosphate rock, silica and carbonaceous reducing agent (coke powder or pulverized coal) to 50% ⁇ 85%-325 mesh, add 1% bentonite ball, and dry preheat through chain dryer.
  • the pellets in the kiln reduction to control the maximum temperature of the solids is 1400 ° C ⁇ 1500 ° C, to adjust the pellet Ca0 / Si0 2 molar ratio of 0. 26 ⁇ 0.
  • the melting point of the pellet is higher than the carbothermal reduction temperature of the phosphate ore in the pellet, and the phosphorus is volatilized from the pellet in the form of phosphorus vapor, and then The central space of the kiln is oxidized into phosphorus pentoxide by the ventilating air, and the heat released by the oxidation is in turn supplied to the reduction reaction, and finally the kiln gas containing phosphorus pentoxide is hydrated and absorbed to obtain phosphoric acid.
  • the above-mentioned kiln phosphoric acid process idea shows a good industrial application prospect, because the principle is to use the carbothermal reduction of phosphate rock to form a gas, transfer the phosphorus in the phosphate ore to the gas phase of the rotary kiln, and utilize the gas.
  • the principle of solid separation makes the phosphorus and the remaining solid matter in the pellets separate well.
  • the P 4 gas transferred to the gas phase of the rotary kiln can react with the oxygen in the gas phase of the rotary kiln to generate P 2 0 5 , which is released.
  • the rotary kiln maintains the carbon-thermal reduction temperature of the phosphate rock, the primary energy source is used, and the combustible material produced by the carbothermal reduction of the phosphate rock and the CO can be subjected to a combustion exothermic reaction inside the rotary kiln, and is supplemented and supplied to maintain the carbon heat of the phosphate rock in the rotary kiln.
  • the energy required to reduce the temperature which is significantly reduced compared to the traditional thermal process phosphoric acid process.
  • Rotary kiln is the equipment whose kiln body runs at a certain speed (0.5 r/mir! ⁇ 3r/min). It has the advantage of continuously mechanically turning and mixing the solid materials sent into the kiln to ensure the solid materials in the kiln. The uniformity of heat is everywhere, but in turn the solid material in the kiln is also subject to the mechanical friction of the material movement. If the material strength is less than the mechanical friction, it will be easily destroyed.
  • the basic principle of the KPA process proposed by the US 0RC company is to finely grind phosphate rock, silica and carbonaceous reducing agent (coke powder or pulverized coal) to 50% ⁇ 85%-325 mesh to make pellets.
  • the material pellets used in the process are equipped with a reducing agent carbon, and the carbon undergoes a rapid oxidation reaction with oxygen in the air at a temperature of more than 350 ° C to be converted into C0 2 , if a conventional metallurgical industrial pellet is used on the grate machine.
  • high temperature consolidation 900 °C
  • the reduced carbon in the pellets is completely oxidized, and the reducing agent is lost in the rotary kiln pellets.
  • the pellets entering the kiln will be pulverized in large quantities due to the mechanical friction that can not withstand the movement of the ball in the rotary kiln.
  • Phosphate powder, silica powder and carbonaceous reducing agent which form pellets after pulverization will be separated, and the phosphate rock powder which is pulverized cannot be reduced due to intimate contact with the carbonaceous reducing agent. More seriously, once the phosphate rock is separated from the silica powder, its melting point will be drastically reduced to below 1250 °C.
  • This powdered phosphate rock passes through the high temperature reduction zone of the rotary kiln (the temperature of the layer is about 1300 °C). , all will change from the solid phase to the liquid phase, and then adhere to the rotary kiln lining to form the high temperature ring of the rotary kiln, hinder the normal movement of the material in the rotary kiln, and join Most of the material of the rotary kiln overflows from the rotary kiln at the feed end of the rotary kiln, and the high temperature reduction of phosphorus cannot be achieved, resulting in process failure. It can be seen that due to the inherent defects of the raw materials entering the kiln, the above-mentioned KPA technology has not been used for any industrialization, scale or commercial application.
  • the solid material zone in the lower part of the rotary kiln belongs to the reduction zone, and the upper part of the zone is the gas flow zone of the rotary kiln, which belongs to the oxidation zone, the feed ball.
  • the group is added from the end of the rotary kiln, and is discharged from the kiln head area of the rotary kiln by its own gravity and the frictional force of the rotary kiln.
  • the burner for burning the rotary kiln is installed in the rotary kiln head, and the combustion fumes generated by the kiln are
  • the tail fan is taken out, and the micro-negative pressure is maintained in the rotary kiln, and the air flow is opposite to the moving direction of the material. Since there is no mechanical isolation zone in the reduction zone (solid layer zone) of the rotary kiln and the oxidation zone (the gas flow zone above the solid layer of the rotary kiln), the ball exposed on the surface of the solid zone zone will be in the gas stream with the oxidation zone.
  • the white shell of 5 the thickness of the shell is generally 300 ⁇ m ⁇ 1000 ⁇ m, and the content of P 2 0 5 in the shell layer can be as high as 30% or more; this will cause the transfer ball to P 2 0 5 in the gas phase to not exceed 60%. , resulting in a yield of phosphate in P 205 is low,
  • the waste of mineral resources and the significant increase in the cost of phosphoric acid production have caused the above-mentioned KPA process to lose its commercial application and industrial promotion value.
  • Some researchers hope to isolate the reduction zone in the rotary kiln through the volatilized gas in the layer. Oxidation zones, but industrial tests conducted in rotary kiln with an inner diameter of 2 m have shown that the presence of P 2 0 5 -rich white shell on the pellet surface is still unavoidable.
  • phosphoric acid is produced according to the KPA process proposed by 0RC, which is still very difficult in large-scale industrial applications and practices.
  • Joseph A. Megy has proposed some improved technical methods for the KPA process (see US Pat. No. 7,910,080 B), which is to set the stop at the discharge end of the kiln head of the rotary kiln cylinder while maintaining the basic KPA process.
  • the material ring is used to increase the solid material filling rate of the rotary kiln.
  • by increasing the diameter of the rotary kiln to reduce the surface area-volume ratio of the material layer in the rotary kiln the probability of the material layer being exposed on the surface of the solid material layer is reduced.
  • the process also adds a portion of petroleum coke to the material entering the rotary kiln, in order to utilize the reducing gas generated by the volatilization of the volatiles in the petroleum coke to cover between the material layer and the oxidation zone of the rotary kiln.
  • the material pellets to be used are double-layer composite structure, and the inner layer is made of phosphate rock, silica (or lime, limestone, etc.) and carbonaceous reducing agent after being ground and mixed.
  • the outer layer is a layer of solid fuel containing more than 20% carbon on the inner layer pellet. The inner and outer layers of the pellet are added with a binder, and the pellet is dried and consolidated.
  • Pellet inner Ca0 / Si0 2 molar ratio may be less than 0.6 or greater than 6.5, the carbonaceous reducing agent is a reducing 1 ⁇ 3 times the theoretical amount of phosphate rock, the solid fuel pellet with an outer layer of the inner layer can amount
  • the mass of the pellet is 5% to 25%;
  • the binder added to the pellet and the outer layer may be asphalt, sodium humate, ammonium humate, water glass, sulfite pulp waste liquid, syrup, lignosulfonate 2% ⁇ 15% ( ⁇ ) ⁇
  • the pellet can be dried and consolidated, the consolidation temperature is 80 ° C ⁇ 600 ° C, and the consolidation time is 3 min ⁇ 120 min.
  • the above method proposed by the method uses a high temperature resistant wrapping material containing solid carbon on the pellet, and a binder is added during the wrapping so that the outer covering can adhere well to the inner pellet.
  • the double-layer composite pellets are dried and consolidated and sent to the rotary kiln.
  • the high temperature zone of the rotary kiln 300 ° C ⁇ 140 (about TC) can achieve the carbothermal reduction of phosphate ore.
  • the surface of the sphere is artificially coated with a coating layer containing a solid reducing agent (carbonaceous material), which can align its inner layer pellets with the gas oxidization zone containing 0 2 and P 2 0 5 in the upper part of the rotary kiln layer. Effective physical isolation.
  • the carbon in the coating layer can undergo a limited oxidation reaction with 0 2 in the oxidation zone (due to the time when the material ball is exposed on the surface of the rotary kiln layer in the industrial large rotary kiln) Shorter, less complete reaction, so that 0 2 can not be transferred to the inner pellet, ensuring that the reducing agent carbon in the inner pellet is not oxidized by the oxygen in the rotary kiln gas flow, so that P 2 0 5 in the phosphate rock the reduction process can be performed completely realized process P 2 0 5 in phosphate Reduction rate.
  • an upper kiln gas stream in the oxidation zone layers P 2 0 5 can not react with the carbon composite pellet surface layer and wrapping, thus preventing the formation of a phosphate or metaphosphate on the composite pellets
  • the salt compound eliminates the formation of P 2 0 5 white shell on the original KPA process sphere, ensuring that the process can obtain a higher P 2 O 5 yield.
  • the method is replaced by solid fuel or Partially replaced Gas or liquid fuel, which further reduces the production cost of phosphoric acid.
  • the concentration of P 2 0 5 in the kiln flue gas is relatively low, and the former flue gas volume of the same scale is 3 to 4 times that of the latter;
  • the kiln flue gas composition of the kiln method is complicated, fluorine, dust, 30 2 and other impurities. Therefore, if the conventional acid-recovering method of thermal phosphoric acid is still used, there are many problems: First, the amount of flue gas of the thermal phosphoric acid is small, and the flue gas flow rate of the corresponding equipment is low, if directly applied to the kiln process phosphoric acid process, The size of the equipment system can be quite large. The equipment system is not only complicated in structure, but also has high investment and operating costs.
  • the flue gas impurity content of the kiln method phosphoric acid is complicated, and the spray acid is more corrosive, and it is necessary to prevent acidity.
  • the clogging of equipment and pipelines by solid impurities requires further improvement of the acid collection process and equipment structure.
  • the kiln method phosphoric acid kiln flue gas also contains fluorine-containing substances harmful to human body (with SiF ⁇ P HF). Form exists), which needs to be recycled while avoiding environmental pollution.
  • the technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a structure with simple structure, reasonable layout, low investment cost, strong adaptability, high utilization rate of raw materials, reduced pollutant emission, and good fluorine recovery effect.
  • a device for recovering fluorine from a flue gas after phosphating a phosphorus in a kiln process phosphoric acid process, and a process for recovering fluorine by using the device is to overcome the deficiencies of the prior art and provide a structure with simple structure, reasonable layout, low investment cost, strong adaptability, high utilization rate of raw materials, reduced pollutant emission, and good fluorine recovery effect.
  • the technical solution proposed by the present invention is an apparatus for recovering fluorine from flue gas after phosphating phosphorus by a kiln process phosphoric acid process, the device comprising a first-stage fluorine absorption tower and a second-stage fluorine absorption tower.
  • the first-stage fluorine absorption tower and the second-stage fluorine absorption tower are both fluidized counter-current washing towers, and the first-stage fluorine absorption tower is mainly composed of a fluorosilicic acid washing tube and a fluorosilicic acid separation tank, and the fluorosilicate washing tube is
  • the inlet is connected to the flue gas conveying pipe after hydration
  • the outlet of the fluorosilicic acid washing pipe is connected to the middle of the fluorosilicic acid separation tank
  • the top of the fluorosilicic acid separation tank is provided with a flue gas outlet
  • the bottom is provided with fluorine silicon.
  • the secondary fluorine absorption tower is mainly composed of a secondary fluorosilicate washing tube and a secondary fluorosilicic acid separation tank, and the flue gas outlet of the first-stage fluorine absorption tower is connected to the secondary fluorosilicate washing tube through a pipeline,
  • the outlet of the fluorosilicic acid washing tube is connected to the middle of the secondary fluorosilicate separation tank, the top of the secondary fluorosilicate separation tank is provided with a defoaming layer and a flue gas outlet, and the bottom is provided with a fluorosilicic acid liquid outlet, the fluorine
  • the silicic acid solution outlet is connected to the nozzle in the secondary fluorosilicate washing tube and the fluorosilicic acid separating tank of the first-stage fluorine absorption tower through a circulating conveying pipe of the circulating pump.
  • the principle of fluorine absorption of the first-stage fluorine absorption tower and the second-stage fluorine absorption tower is mainly as follows: after hydration and phosphorus absorption in a reverse-flow type fluorosilicate washing tube
  • the flue gas collides with the upwardly sprayed circulating concentrated fluorosilicic acid solution, thereby forcing the liquid to radiate from the inside out to the pipe wall, thereby establishing a foam zone (foam column) at a certain height at the gas-liquid interface.
  • the foam column moves up and down along the pipe body according to the change of the relative momentum of the gas and liquid. As the gas contacts the continuously updated liquid surface, particle trapping and gas absorption occur in the foam zone, and heat is transferred accordingly.
  • the circulating transport pipeline in the secondary fluorine absorption tower is further provided with a fluorosilicic acid cooler, and the liquid outlet of the fluorosilicic acid cooler is divided into two paths, one way and the said The nozzles in the secondary fluorosilicate washing tube are in communication, and the other is in communication with the spray layer on the top of the secondary fluorosilicate separating tank.
  • the flue gas outlet of the secondary fluorine absorption tower is further connected to a tail suction tower, the tail suction tower is a spray empty tower, and the top of the tail suction tower is provided with smoke.
  • a spray layer is arranged on the upper side of the tower, and an alkali absorption liquid tank is arranged at the bottom, and the outlet of the alkali absorption liquid tank is connected to the spray layer in the tail suction tower through a circulation conveying pipe with a circulation pump.
  • the present invention also provides a process for recovering fluorine from flue gas after phosphating phosphorus by a kiln process phosphoric acid process using the apparatus of the present invention described above, comprising the steps of:
  • (1) Primary fluorine absorption First, the hydrated phosphorus-absorbing flue gas is sent to the fluorosilicic acid washing tube of the first-stage fluorine absorption tower, and the circulation of the flue gas from the top to the bottom and the nozzle from the bottom to the top is injected.
  • the fluorosilicic acid solution undergoes sufficient gas-liquid two-phase contact, and undergoes mass transfer heat transfer and chemical reaction (fluorine in the flue gas (mainly silicon tetrafluoride) reacts with water in the circulating fluorosilicic acid solution), the reaction Producing fluorosilicic acid, and the enthalpy in the flue gas is partially transferred to the water vapor through the moisture in the adiabatic evaporation cycle fluorosilicic acid solution;
  • fluorine in the flue gas mainly silicon tetrafluoride
  • the first-order fluorine absorption uses a circulating fluorosilicic acid solution having a mass concentration of 8% to 25% (more preferably 10% to 20%), and the circulating fluorosilicic acid
  • the temperature of the solution is from 25 ° C to 65 ° C (more preferably from 50 ° C to 65 ° C), and the spray liquid to gas ratio is controlled at 3 L/m 3 to 25 L/m 3 (more preferably 3 L/m 3 to 6 L/m).
  • the temperature of the circulating fluorosilicic acid solution used in the step (3) is 0.5% ⁇ 5%, and the temperature of the circulating fluorosilicic acid solution is 25 °C ⁇ 60 °C ( More preferably, the temperature is from 3 L/m 3 to 25 L/m 3 (more preferably from 3 L/m 3 to 6 L/m 3 ).
  • the circulating fluorosilicic acid solution entering the secondary fluorosilicate washing tube is subjected to cooling treatment by the fluorosilicic acid cooler, and the smoke treated by the step (3)
  • the temperature of the gas drops below 60 °C.
  • the hydrated phosphorus-absorbing flue gas is obtained by hydration absorption by a phosphoric acid system
  • the phosphoric acid system comprises a hydration tower, an acid circulation spray system, and a phosphoric acid mist trap.
  • the body of the hydration tower is a spray empty tower, the lower part of the hydration tower is provided with a flue gas inlet for the flue gas of the rotary kiln, and the top is provided with a flue gas outlet, and the hydration tower above the flue gas inlet a spray device is disposed in the cavity, the liquid inlet of the acid circulation spray system is disposed at the bottom of the hydration tower, and the liquid outlet of the acid circulation spray system is connected to the liquid inlet of the spray device
  • the acid liquid circulation spraying system is further provided with an acid liquid storage tank and a circulation pump;
  • the phosphoric acid mist trapping tower is a fluidized countercurrent scrubbing tower, which is mainly composed of a washing pipe and a separating tank.
  • the flue gas outlet of the hydrating tower is connected to the inlet of the washing pipe through a pipe, and the outlet of the washing pipe Connected to the middle of the separation tank, the top of the separation tank is provided with a flue gas outlet, and the bottom is provided with an acid outlet, and the acid outlet is connected to the nozzle in the washing tube through a circulating conveying pipe with a circulation pump;
  • the flue gas outlet of the phosphoric acid mist trapping tower is connected to the lower part of the defogging separation tower through a pipeline, and the defogging separation tower is provided with an on-line water washing device, and the top of the defogging separation tower is provided with a flue gas outlet to discharge water.
  • the flue gas after the phosphorus absorption is provided with an acid outlet at the bottom, and the acid liquid outlet is connected to the acid liquid inlet of the phosphoric acid mist trap tower through a pipeline.
  • the hydration tower is equipped with a cooling system, and the cooling system includes a and/or b in the following structure :
  • the outer wall of the cavity of the hydration tower is covered with a water cooling system
  • An acid cooler is disposed in the acid circulation spray system near the liquid inlet.
  • the upper part of the defogging separation tower is installed with a screen mist eliminator, and the lower part is designed as a phosphor droplet collecting structure similar to a cyclone, and the online water washing device is installed in the screen. Above the fog.
  • the shower device comprises at least two sprays at different heights of the vat chamber. a layer, and at least two spray layers comprise a dilute phosphoric acid spray layer and a concentrated phosphoric acid spray layer, the concentrated phosphoric acid spray layer is disposed above the dilute phosphoric acid spray layer; and the concentrated phosphoric acid spray layer of the liquid inlet tube
  • the acid liquid circulating spray system is connected, the liquid inlet pipe of the dilute phosphoric acid spray layer is connected with the circulating conveying pipe of the phosphoric acid mist collecting tower; the conveying pipe after the circulating pump in the acid liquid circulating spraying system It is connected to the acid inlet of the phosphoric acid mist trap through a tube.
  • the fluorine recovery device of the present invention greatly improves and optimizes the structure and connection relationship of the existing fluorine recovery device, so that the structure of the entire device is more simplified and reasonable, and can better match the hydration absorption of phosphoric acid.
  • the process route needs, and can adjust and optimize the integration performance of the equipment according to the specific requirements of the process, such as economy, environmental protection, investment cost, etc., and has stronger adaptability;
  • the fluorine recovery device of the invention greatly simplifies the system structure and reduces the investment, operation and maintenance costs of the device;
  • the device of the invention is fully applicable to the direct production of phosphoric acid in low-grade phosphate rock, and is of great significance for the effective utilization of a large number of low-grade phosphate rock in China.
  • FIG. 1 is a schematic structural view of a fluorine recovery apparatus according to a specific embodiment of the present invention.
  • FIG. 2 is a flow chart of a fluorine recovery process in a specific embodiment of the present invention.
  • FIG. 3 is a schematic view showing the structure of a phosphoric acid system in a specific embodiment of the present invention.
  • FIG. 4 is a schematic enlarged view showing the structure of a hydration tower of a phosphoric acid plant in an embodiment of the present invention.
  • Fig. 5 is a schematic enlarged view showing the structure of a phosphoric acid mist trapping tower of a phosphoric acid plant according to an embodiment of the present invention.
  • First-stage fluorine absorption tower 51, fluorosilicic acid washing tube; 52, fluorosilicic acid separation tank; 53, fluorosilicic acid liquid outlet; 54, fluorosilicic acid refining equipment; 6, secondary fluorine absorption tower; 61, secondary fluorosilicate washing tube; 62, secondary fluorosilicic acid separation Cans; 63, fluorosilicic acid cooler; 7, tail suction tower; 8, fan.
  • the first-stage fluorine absorption tower 5 is mainly composed of a fluorosilicic acid washing tube 51 and a fluorosilicic acid separation tank 52, and the inlet of the fluorosilicic acid washing tube 51 is connected to the conveying pipe of the hydrated phosphorus-absorbing flue gas, and the fluorosilicic acid washing tube
  • the outlet of 51 is connected to the middle of the fluorosilicic acid separation tank 52, the top of the fluorosilicic acid separation tank 52 is provided with a flue gas outlet 12, the bottom is provided with a fluorosilicic acid liquid outlet 53, and the fluorosilicic acid liquid outlet 53 is passed through a belt circulation pump.
  • the circulating conveying pipe of 2 is in communication with the nozzle 35 in the fluorosilicate washing pipe 51, and the fluorosilicic acid separating tank 52 serves as an acid circulation tank of the circulating conveying pipe.
  • the structure of the secondary fluorine absorption tower 6 in this embodiment is similar to that of the first-stage fluorine absorption tower 5.
  • the secondary fluorine absorption tower 6 is mainly composed of a secondary fluorosilicate washing tube 61 and a secondary fluorosilicate separation tank 62.
  • the flue gas outlet 12 of the fluorine absorption tower 5 is connected to the inlet of the secondary fluorosilicate washing tube 61 through a pipe, and the outlet of the second-stage fluorosilicate washing tube 61 is connected to the middle of the second-stage fluorosilicic acid separation tank 62, the secondary fluorine
  • the top of the silicic acid separation tank 62 is provided with a defoaming layer and a flue gas outlet 12, and the bottom is provided with a fluorosilicic acid liquid outlet 53, which passes through a circulating conveying pipe of the circulating pump 2 and a secondary fluorosilicic acid.
  • the nozzles 35 in the washing tube 61 are in communication.
  • the circulating transport pipeline of the secondary fluorine absorption tower 6 is further provided with a fluorosilicic acid cooler 63, a fluorosilicic acid cooler.
  • the inlet of 63 is connected to the circulation pump 2, and the outlet is divided into two paths, one is connected to the nozzle 35 in the secondary fluorosilicate washing pipe 61, and the other is connected to the spray layer on the top of the secondary fluorosilicate separation tank 62.
  • the secondary fluorosilicic acid separation tank 62 also serves as an acid circulation tank for the circulating conveying pipe.
  • the outlet of the circulation pump 2 of the secondary fluorine absorption tower 6 is also connected to the inlet of the fluorosilicic acid separation tank 52 of the primary fluorine absorption tower 5 through a branch pipe, whereby the fluorosilicic acid solution of the secondary fluorine absorption tower 6 can be removed.
  • the string is passed to the first-stage fluorine absorption tower 5.
  • the equipment for recovering fluorine in the present embodiment is finally connected with a tail suction tower 7, which is a spray empty tower, and the flue gas outlet 12 of the second-stage fluorine absorption tower 6 passes.
  • the pipe is in communication with the flue gas inlet 11 of the tail suction tower 7.
  • the top of the tail suction tower 7 is provided with a flue gas outlet 12, a spray layer is arranged above the tower, and an alkali absorption liquid tank (sodium hydroxide) is arranged at the bottom, and the alkali absorption liquid tank outlet passes through the circulating conveying pipeline with the circulation pump 2. It is connected with each spray layer in the tail suction tower 7, thereby forming an exhaust gas absorption circulating spray system.
  • the above-mentioned fluorosilicic acid liquid outlet 53 is additionally passed through a pipe with a feed pump and an external fluorosilicic acid refining device 54 (or a fluoride salt).
  • the processing apparatus is connected to the fluorosilicic acid refining apparatus 54 before being introduced into the fluorosilicic acid refining apparatus 54 by a filter press apparatus 21, and the overflow port of the filter press apparatus 21 is connected to the fluorosilicic acid refining apparatus 54 through a pipe.
  • the flue gas is further cooled to 50 ° C ⁇ 70 ° C by means of adiabatic evaporation of the water in the fluorosilicic acid solution and heat transfer to the circulating flu
  • (2)-stage gas-liquid separation The gas and liquid in the fluorosilicic acid washing tube 51 are all transferred to the fluorosilicic acid separation tank 52 for gas-liquid separation, and the separated gas passes through the flue gas of the first-stage fluorine absorption tower 5.
  • the outlet enters the secondary fluorosilicate washing tube 61 of the secondary fluorine absorption tower 6, and the separated liquid remains in the fluorosilicic acid separation tank 52 and is returned to the fluorosilicate washing tube 51 through the circulation conveying pipe with the circulation pump 2.
  • Secondary gas-liquid separation The gas and liquid in the secondary fluorosilicate washing tube 61 are all transferred to the secondary fluorosilicate separation tank 62 for gas-liquid separation, and the separated gas passes through the secondary fluorine absorption tower.
  • the flue gas outlet of 6 enters the subsequent tail suction tower 7 for treatment, and the separated liquid remains in the secondary fluorosilicate separation tank 62 and is returned to the secondary fluorosilicate washing tube 61 through the circulating conveying pipe with the circulation pump 2.
  • the circulating conveying pipe is provided with a fluorosilic acid cooler 63, and the circulating fluorosilicic acid solution entering the secondary fluorosilicate washing pipe 61 is subjected to cooling treatment by the fluorosilicic acid cooler 63; Part of the circulating fluorosilicic acid solution is directly discharged into the fluorosilicic acid separation tank 52 of the primary fluorine absorption tower 5;
  • the filter residue is silica gel, which is used as a by-product after washing and removing impurities.
  • the flue gas entering the subsequent tail suction tower 7 for treatment is in countercurrent contact with the downwardly circulated circulating absorption solution during the upward movement of the tail suction tower 7, and the bottom absorption tank of the tail suction tower 7 passes through the circulation pump 2 and each of the towers.
  • the spray layers are connected to form a circulating spray system; in order to maintain absorption
  • the absorption capacity of the liquid the pH value of the absorption liquid is kept above 8, and it is necessary to continuously add a dilute alkali solution (sodium hydroxide solution), and the absorption liquid is added by the dilute alkali solution and the P 2 0 5 , fluorine, etc. in the flue gas.
  • the absorption of impurities will accumulate and need to be continuously discharged for sewage treatment.
  • the treated water can be reused in the raw material process of kiln phosphoric acid; the remaining pollutants in the flue gas (P 2 0 5 , SiF 4 , dust, etc.) are sprayed.
  • the leaching liquid is absorbed, and the flue gas is further washed and purified to meet the national emission standard, and then discharged to the chimney through the induced draft fan.
  • the flue gas after hydration and phosphorus absorption is obtained by hydration absorption of a phosphoric acid system as shown in FIG. 3 to FIG. 5, and the phosphoric acid system includes a hydration tower 1, an acid circulation spray system, The phosphoric acid mist collecting tower 3 and the defogging separation tower 4.
  • the body of the hydration tower 1 of the present embodiment is a spray empty tower, the lower part of the hydration tower 1 is provided with a flue gas inlet 11 for discharging kiln flue gas, and the top is provided with a flue gas outlet 12 after hydration absorption, smoke
  • a sprinkler device 13 is disposed in the cavity of the hydration tower 1 above the gas inlet 11, and the liquid inlet 14 of the acid circulation sprinkler system is disposed at the bottom of the hydration tower 1, and the liquid outlet 15 of the acid circulation sprinkler system
  • the acid inlet tank 16 and the circulation pump 2 are also connected to the inlet pipe of the sprinkler device 13, and the acid circulation sprinkler system.
  • the outer wall of the chamber of the hydration tower 1 of the present embodiment is covered with a water cooling system 17, and the cooling water in the water cooling system 17 is taken in and out.
  • an acid cooler 18 is disposed in the acid circulation spray system near the liquid inlet port 14; the outlet of the acid cooler 18 is connected to the inlet of the acid liquid storage tank 16, and the outlet of the acid liquid storage tank 16
  • the circulation pump 2 is connected to the inlet pipe of the shower device 13, thereby forming an acid circulation shower system.
  • the phosphoric acid mist trapping tower 3 of the present embodiment is a high-efficiency fluidized countercurrent scrubbing tower, which is mainly composed of a washing pipe 31 and a separating tank 32.
  • the flue gas outlet 12 of the hydrating tower 1 passes through the inlet of the pipe and the washing pipe 31.
  • the outlet of the washing tube 31 is connected to the middle of the separation tank 32, the top of the separation tank 32 is provided with a flue gas outlet 12, and the bottom is provided with an acid outlet 33, which passes through a circulating conveying pipe of the circulating pump 2
  • the separator 35 is in communication with the nozzle 35 in the washing tube 31 (see Fig. 5), and serves as an acid circulation tank for circulating the conveying pipe in the phosphoric acid mist collecting tower 3.
  • the spraying device 13 of the hydration tower 1 in this embodiment is provided with three spray layers at different heights of the liquefaction tower 1, and three
  • the spray layer comprises a dilute phosphoric acid spray layer 25 and two concentrated phosphoric acid spray layers 24 (see Figure 4), and two concentrated phosphoric acid spray layers 24 are disposed above the dilute phosphoric acid spray layer 25;
  • the liquid inlet pipe of the layer 24 is in communication with the acid circulating spray system of the hydration tower 1, and the inlet pipe of the dilute phosphoric acid spray layer 25 is connected to the circulating conveying pipe of the phosphoric acid mist collecting tower 3, so that the first realization is achieved.
  • the acid liquid in the phosphoric acid mist collecting tower 3 is sent to the hydration tower 1. Further, on the conveying pipe after circulating the pump 2 in the above-mentioned acid liquid circulating spray system, it is connected to the acid liquid inlet 34 of the phosphoric acid mist collecting tower 3 through a pipe.
  • the branch pipe is provided with a packing filtering device 22, and the acid inlet of the packing filtering device 22 is connected to the acid circulating spraying system through the branch pipe, and the filtrate outlet of the packing filtering device 22 is Divided into three ways, all the way to the acid liquid inlet 34 of the phosphoric acid mist collecting tower 3, one way to the external phosphoric acid refining device 23, the other way to the acid liquid storage tank 16; the bottom outlet of the packing filter device 22 passes
  • the pipe is connected to the feed port of the filter press device 21, and the overflow port of the filter press device 21 is passed through the pipe and the acid circulation spray system.
  • the acid liquid storage tank 16 is connected to fully realize the recovery and utilization of phosphoric acid, thereby ensuring high yield of phosphoric acid.
  • the flue gas outlet 12 of the phosphoric acid mist collecting tower 3 is connected to the lower portion of the defogging separation tower 4 through a pipe, and the flue gas outlet 12 is disposed at the top of the defogging separation tower 4 to discharge the hydrated phosphorus.
  • the gas is provided with an acid outlet 33 at the bottom, and the acid outlet 33 is connected to the acid inlet 34 of the phosphoric acid mist collecting tower 3 through a pipe.
  • the defogging separation tower 4 is provided with an in-line water rinsing device 41, and the water added by the in-line water rinsing device 41 can simultaneously serve as hydration for the entire hydration absorption phosphoric acid process, and is gradually returned to the upstream phosphorous mist trapping tower 3 through a pipeline. And in the hydration tower 1.
  • the upper portion of the defogging separation tower 4 is provided with a screen mist eliminator 42, and the lower portion is designed as a phosphor droplet collecting structure similar to a cyclone.
  • the on-line water rinsing device 41 is installed above the screen demister 42.
  • the flue gas containing P 2 0 5 and fluorine (specially, the kiln flue gas above 500 ° C in the KPA kiln process phosphoric acid process, containing P 2 0 5 80 g/Nm 3 ) is imported from the flue gas in the lower part of the hydration tower 1 11 into the tower, before the circulation pump 2 of the acid circulation spray system is turned on, so that the concentrated phosphoric acid solution in the hydration tower 1 is sprayed through the upper and middle two layers of concentrated phosphoric acid spray layer 24, the uppermost layer of concentrated phosphoric acid spray Part of the nozzle of layer 24 is sprayed obliquely downward to the inner wall of the tower, and the other nozzles are sprayed vertically downward.
  • fluorine specially, the kiln flue gas above 500 ° C in the KPA kiln process phosphoric acid process, containing P 2 0 5 80 g/Nm 3
  • the nozzles of the middle and lower spray layers are sprayed vertically downward, and the concentrated phosphoric acid solution sprayed and the P containing the tower 205 and fluorine full contact countercurrently the flue gas, heat and mass transfer for generating the concentrated acid phosphate P 205 and the flue gas in the spray water chemical reaction to generate more than half of the phosphoric acid to be absorbed into the
  • the spray liquid, the rest of the phosphoric acid mist is kept in the gas phase, and the fluorine in the flue gas (such as SiF ⁇ P HF, etc.) is difficult to be absorbed into the spray liquid under concentrated phosphoric acid and higher temperature conditions;
  • the temperature of the circulating concentrated phosphoric acid solution of the effluent column 1 is raised to 70 ° C to 95 ° C.
  • the mass concentration of the concentrated phosphoric acid solution sprayed in the spray can be selected from the range of 60% to 90% (in this embodiment, a phosphoric acid solution having a concentration of 70% to 85%), the hydration tower
  • the temperature of the inlet of the concentrated phosphoric acid solution is controlled to 50 ° C ⁇ 8 (TC, the spray liquid to gas ratio is controlled at 3 L / m 3 ⁇ 20 L / m 3 .
  • TC the spray liquid to gas ratio
  • the phosphoric acid mist cannot be settled in the hydration tower 1 and is taken out of the hydration tower 1 along with the flue gas.
  • the hydration tower 1 has the dual functions of cooling flue gas and hydration absorption P 2 0 5 , among which mainly occurs.
  • the chemical reaction is as follows.
  • the concentrated phosphoric acid solution sprayed down in the hydration tower 1 finally enters the acid circulation spray system through the liquid inlet 14 and then flows into the acid cooler 18, and the structure of the acid cooler 18 is a stainless steel tube arranged in a stirring tank.
  • the heat exchanger plate is formed into a circulating cooling water, and the phosphoric acid solution entering the acid cooler 18 is forced to form a forced convection heat transfer on the heat exchange plate to improve the heat transfer efficiency and heat the concentrated phosphoric acid.
  • the heat of the circulating concentrated phosphoric acid solution is continuously transferred by the cooling water.
  • the gas phase material i.e., flue gas
  • the gas phase material discharged from the flue gas outlet 12 at the top of the hydration tower 1 enters the washing tube 31 of the phosphoric acid mist collecting tower 3, which is a fluidized countercurrent washing tower, which is in the washing tube 31.
  • the dilute phosphoric acid solution is sprayed downward and upward, and the dilute phosphoric acid solution forms a strong turbulent region in the gas-liquid interface region after colliding with the high-speed flue gas flow from the top to the bottom, and a stable foam is established after the fluid momentum reaches equilibrium.
  • Zone foam column
  • the flue gas passes through the foam zone, and is in contact with a large surface of the continuously updated phosphoric acid solution liquid surface.
  • the phosphorous mist trapping tower of the invention can greatly reduce the power head loss of the equipment and reduce the energy consumption of the acid collecting device under the same demisting effect.
  • the acid solution circulating in the phosphoric acid mist collecting tower 3 is a dilute phosphoric acid solution having a mass concentration of 10% to 50%, and the gas and liquid in the washing tube 31 enter the separation tank 32 in the lower portion of the column for gas-liquid separation, circulating acid. The liquid falls into the bottom of the separation tank 32.
  • the separation tank 32 of the tower also serves as a circulating acid tank, and the dilute phosphoric acid solution at the bottom is sent back to the washing tube 31 through the circulation pump 2 or the dilute phosphoric acid spray of the acid to the hydration tower 1 as needed. In layer 25.
  • the flue gas discharged from the flue gas outlet 12 in the phosphoric acid mist trap tower 3 is further introduced into the defogging separation tower 4 for further gas-liquid separation to further remove the phosphoric acid mist in the flue gas, and the lower portion of the defogging separation tower is designed Similar to the cyclone trapping structure 43 of the cyclone dust collector, the grown phosphoric acid droplets are collected from the flue gas by centrifugal force, and a screen demister 42 is installed in the upper part of the defogging separation tower, and the flue gas is Phosphorus droplets that have not yet grown up are further captured to ensure the direct yield of the device to P 2 0 5 ; the flue gas after the phosphating phosphorus removal by the defogging separation tower 4 is sent to the fluorine recovery equipment for fluorine recovery. deal with.
  • the P 2 0 5 in the flue gas needs to consume water, and in the process of cooling the flue gas, part of the water is evaporated from the sprayed acid solution, so the hydration absorption process needs to continuously replenish water, the process of this embodiment
  • the amount of water that needs to be replenished in the system is all replenished from the flue gas outlet 12 of the defogging separation tower 4, and the in-line water washing device 41 serves not only as a water replenishing device but also as a flushing device for the upper screen demisters of the defogging separation tower 4. .
  • the bottom liquid of the defogging separation tower 4 is returned to the phosphoric acid mist collecting tower 3 through the acid liquid inlet 34 of the phosphoric acid mist collecting tower 3, so the phosphoric acid mist is trapped.
  • the concentration of circulating acid in the tower 3 will gradually decrease.
  • the hydration tower 1 continuously absorbs P 2 0 5 in the flue gas, and the circulating acid concentration will gradually increase.
  • the hydration tower 1 and The circulating acid liquid system of the phosphoric acid mist trapping tower 3 needs to carry out string acid to maintain the stability of the respective circulating acid liquid concentrations, and the acid of the hydrating tower 1 string to the phosphoric acid mist collecting tower 3 is clarified and filtered in the packing filtering device 22.
  • the acid of the phosphoric acid mist collecting tower 3 to the hydrating tower 1 is directly taken out from the outlet of the circulating pump 2 of the phosphoric acid mist collecting tower 3, and the excess phosphoric acid in the process system is corresponding (corresponding to The acid balance of the material balance is also taken out from the supernatant outlet of the packing filter device 22 and then enters the refining process, adding activated carbon, diatomaceous earth and strontium.
  • the salt, the color of the crude phosphoric acid and the so 4 2 - were removed and then filtered through a plate and frame filter press to obtain a concentrated phosphoric acid product.

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Abstract

本发明公开了一种用于从窑法磷酸工艺水化吸磷后的烟气中回收氟的设备及工艺，该设备包括一、二级氟吸收塔，且均为流态化逆流式洗涤塔，一级氟吸收塔主要由氟硅酸洗涤管和氟硅酸分离罐组成，分离罐顶部设有烟气出口，底部的氟硅酸液出口通过循环输送管道与氟硅酸洗涤管相连通；二级氟吸收塔的主体结构与一级氟吸收塔类似，二级氟硅酸分离罐的顶部设有除沫层和烟气出口，底部的氟硅酸液出口通过循环输送管道与二级氟硅酸洗涤管内的喷嘴和一级氟吸收塔的氟硅酸分离罐相连通。本发明的氟回收工艺依次包括一级氟吸收、一级气液分离、二级氟吸收、二级气液分离等多个操作。本发明具有结构简单、投资成本低、原料利用率高、氟回收效果好等优点。

Description

用于从窑法磷酸工艺水化吸磷后的烟气中回收氟的设备及工艺
【技术领域】
本发明涉及一种从烟气中回收含氟物质的设备及工艺方法， 尤其涉及一种从窑法磷酸工 艺 （KPA) 的水化吸磷后的烟气中回收氟的设备及工艺。
【背景技术】
目前世界上工业生产磷酸的方法主要有两种。 （1 ) 湿法制磷酸： 即利用硫酸分解磷矿石 得到稀磷酸和以 CaS04 · η¾0为主体的固体废渣（简称磷石膏），将稀磷酸浓缩得到含磷酸 54% 左右的湿法磷酸。 这种工艺的主要缺点： 一是要耗用大量的硫酸； 二是废渣磷石膏无法得到 有效的利用， 其中夹带的硫酸、 磷酸和可溶性氟化物均溶于水， 自然堆放后被雨水冲刷， 容 易对环境造成严重污染； 三是产品磷酸的杂质含量较高， 一般只用于生产肥料； 四是为保证 产品的经济性， 必须使用高品位磷矿。 （2 ) 热法制磷酸： 即首先将将磷矿石、 硅石、 碳质固 体还原剂置于一台矿热电炉中， 用电短路形成电弧的能量， 将炉内温度加热到 1300°C以上， 将磷矿石中的磷以 形式还原出来， 同时碳质固体还原剂被转化为 C0， 将排出矿热炉的 P4 和 CO为主的气体用水洗涤降温， P4被冷却成固体与气相分离， 得到产品黄磷， 含 CO的废气 在烟囱出口点火燃烧后排入大气； 将得到的 加热到 80°C左右， 使其变为液相， 将其在水化 塔中与通入的空气发生氧化燃烧反应， 得到磷酸酐 P205， 再用水吸收得到磷酸。 热法制磷酸 的主要缺点： 一是要耗费大量的电能； 二是排出矿热炉后分离了 P4的气体还夹带有大量的氟 化物（以 SiF^P HF存在）和少量未沉淀的气体 P4， 这将对大气环境造成严重污染； 三是含大 量 CO的气体直接燃烧排空， 能源浪费很大； 四是为了保证生产的经济性， 同样需要使用高品 位磷矿石。
为了克服电能紧张、 硫铁矿资源不足和高品位磷矿石逐年减少对磷酸生产的影响， 八十 年代初美国 Occidental Research Corporation ( 0RC) 提出采用 KPA法， 即用回转窑生产 磷酸的方法（简称窑法磷酸工艺） （参见 Frederic Ledar and Won C. Park等， New Process for Technical-Grade Phosphoric Acid, Ind. Eng. Chem. Process Des. Devl985, 24, 688-697)， 并进行了 0. 84m (内） X 9. 14m回转窑中试装置的中间试验 （参见 US4389384号美国专利文 献）。 该方法是将磷矿石、 硅石和碳质还原剂（焦粉或煤粉）细磨到 50%〜85%— 325目， 配加 1%的膨润土造球， 经链式干燥机干燥预热后送入窑头燃烧天然气的回转窑中， 球团在窑内还 原， 控制最高固体温度为 1400°C〜1500°C， 调整球团 Ca0/Si02摩尔比为 0. 26〜0. 55， 使球团 熔点高于球团中磷矿石的碳热还原温度， 磷以磷蒸气的形式从球团中还原挥发出来， 然后在 窑的中部空间被通入的空气氧化成五氧化二磷， 氧化放出来的热反过来又供给还原反应， 最 后将含有五氧化二磷的窑气水化吸收即制得磷酸。
上述的窑法磷酸工艺思路显示了一种良好的工业应用前景， 因其原理是利用磷矿的碳热 还原形成 气体， 将磷矿石中的磷转移到回转窑的气相当中， 并利用气固分离原理使磷与料 球中的其余固体物质很好的进行分离， 转移到回转窑气相中的 P4气体可与回转窑气相中的氧 发生氧化放热反应生成 P205， 放出的热则供给料球中磷矿石的碳热还原 （吸热反应）， 最后将 出回转窑的含 P205的窑气水化吸收， 可获得洁净度远高于湿法磷酸的工业磷酸。 由于回转窑 维持磷矿碳热还原温度使用的是初级能源，同时磷矿碳热还原产生的可燃物质 与 CO在回转 窑内部即可进行燃烧放热反应， 补充提供给维持回转窑磷矿碳热还原温度所需能量， 这与传 统的热法制磷酸工艺相比， 其能耗得到大幅度降低。
然而， 我们的研究表明， 上述的窑法磷酸工艺在规模化的工业应用及实践中很难实现， 其主要缺陷在于：
1、 回转窑是窑体以一定速度（0. 5r/mir！〜 3r/min )运转的设备， 其优点是可以连续对送 入窑内的固体物料进行机械翻转、 混合， 保证窑内固体物料各处受热的均匀性， 但反过来窑 内固体物料亦须承受物料运动的机械摩擦力， 如果物料强度小于受到的机械摩擦力将很容易 被破坏。 美国 0RC公司提出的 KPA工艺基本原理是将磷矿石、 硅石和碳质还原剂 （焦粉或煤 粉） 细磨到 50%〜85%— 325 目后制成球团， 这三种物质必须紧密地共聚一体， 才能在混合物 中 Ca0/Si02摩尔比为 0. 26〜0. 55 的条件下， 实现混合物料在磷矿石的碳热还原温度下不熔 化， 同时， 磷矿的碳还原才能得以顺利进行。 但工艺使用的物料球团中配入了还原剂碳， 碳 在大于 350 °C温度下会与空气中的氧发生快速的氧化反应转变成 C02， 如果采用传统冶金工业 球团在链篦机上高温固结的方法 （ 900 °C )， 则球团中的还原碳会被全部氧化， 入回转窑球 团则流失了还原剂， 磷的碳热还原反应自然也无法进行， 导致工艺失败。 如果仅通过添加膨 润土作球团粘结剂在 300 °C以下进行干燥脱水， 则球团抗压强度仅为 10KN/个球左右， 落下强 度 1次 /米； 因为膨润土的作用机理主要是利用其物质结构中的层间水来调节球团干燥过程 中的水分释放速率， 提高球团在干燥过程中的爆裂温度， 其本身对提高球团强度并无显著作 用。 将这种球团送入回转窑后、 且在回转窑温度值达到 900 °C温度前， 由于承受不住回转窑 内料球运动所受到的机械摩擦力， 入窑的球团将大量粉化， 粉化后组成球团的磷矿粉、 硅石 粉和碳质还原剂等将分离， 粉化后的磷矿粉由于不能与碳质还原剂紧密接触， 将导致磷不能 被还原。 更为严重的是， 磷矿粉一旦与硅石粉分开， 其熔点将急剧降低到 1250 °C以下， 这种 粉状磷矿通过回转窑的高温还原区 （料层温度为 1300 °C左右） 时， 将全部由固相变成液相， 进而粘附在回转窑窑衬上形成回转窑的高温结圈， 阻碍物料在回转窑内的正常运动， 使加入 回转窑的大部分物料从回转窑加料端溢出回转窑， 无法实现磷的高温还原， 导致工艺失败。 可见， 由于入窑原料存在固有缺陷， 至今未见上述的 KPA技术进行过任何工业化、 规模化或 商业化的应用。
2、对于上述配碳磷矿球团的 KPA工艺而言， 在回转窑内料层下部的固体料层区属于还原 带， 料层上部则是回转窑的气流区， 属于氧化带， 进料球团从回转窑窑尾加入， 依靠其自身 重力和回转窑旋转的摩擦力从回转窑的窑头区排出， 回转窑燃烧燃料的烧嘴安装在回转窑窑 头， 产生的燃烧烟气则由窑尾的风机引出， 回转窑内维持微负压， 气流与物料的运动方向相 反。 由于在回转窑的还原带 （固体料层区） 和氧化带 （回转窑固体料层上部的气流区） 无机 械隔离区， 因此， 暴露在固体料层区表面的料球将与氧化带气流中的 、 （¾发生对流传质； 这一方面会使料球中的还原剂碳在料球被气流传热加热到磷矿石碳还原温度前被部分氧化 掉， 致使料球在回转窑还原带由于碳质还原剂的缺乏， 而得不到充分还原； 更为严重的是， 在回转窑高温区暴露于料层表面的料球， 会与窑气中已经还原生成的 P205发生进一步的化学 反应， 生成偏磷酸钙、 磷酸钙及其他的偏磷酸盐或磷酸盐， 进而导致已被还原到气相中的磷 又重新返回料球，并在料球表面形成一层富含 P205的白壳，壳层厚度一般在 300 μ m〜1000 μ m， 壳层中 P205含量可高达 30%以上； 这样会致使料球转移到气相中的 P205不超过 60%， 造成磷矿 中 P205的收率偏低， 进而造成矿产资源的浪费及磷酸生产成本的大幅度上升， 使上述的 KPA 工艺丧失商业应用和工业推广价值。 有研究人员寄望通过料层中挥发出的气体来隔离回转窑 中的还原带与氧化带， 但在内径 2m的回转窑中进行的工业试验表明， 球团表面出现富含 P205 的白壳现象仍是不可避免的。
鉴于上述提及的技术缺陷， 按照 0RC公司所提出的 KPA工艺来生产磷酸， 这在规模化的 工业应用及实践中还存在很大困难。
Joseph A. Megy对 KPA工艺提出过一些改进的技术方法 （参见 US7910080B号美国专利文 献）， 即在维持 KPA基本工艺方法不变的前提下， 通过在回转窑筒体的窑头泄料端设置挡料圈 以提高回转窑的固体物料填充率， 与此同时， 通过增大回转窑的直径以减少回转窑内料层的 表面积-体积比， 降低料层物料暴露在固体料层表面的几率， 以缩短料球中还原剂碳被回转窑 窑气中的 氧化的时间， 减少料球到达回转窑还原带前的还原剂碳的烧损， 同时减少回转窑 高温区中料球表面磷酸盐或偏磷酸盐的生成。 另外， 该工艺还通过在入回转窑的物料中加入 部分石油焦， 以希望利用石油焦中挥发分受热挥发产生的还原性气体， 使其覆盖在料层与回 转窑气流氧化区之间， 以进一步阻止回转窑气流中 、 P205与料球反应的几率， 以保证工艺的 正常进行。 然而， 提高回转窑的填充率将使料球在回转窑内承受更大的机械摩擦力， 进而将 造成料球在回转窑内更大比例的粉化， 形成更多的小于磷矿碳热还原温度的低熔点物质， 使 回转窑高温结圈更加迅速和严重， 从而更早造成工艺的失败。 而添加少量的石油焦产生的挥 发分不足以产生足够的气体， 难以在回转窑固体料层与回转窑内气流区之间形成有效的隔离 层， 若加入量过大， 则出回转窑物料中将夹带有大量的燃料， 这会导致在后续工艺的渣球冷 却机中， 剩余燃料将与冷却渣球的空气相遇并迅速燃烧， 燃烧放出的大量热量不仅增加了出 回转窑高温渣球冷却的难度， 而且又大大提高了工艺的生产成本， 使工艺的商业化、 规模化 运用变得不可实现。
鉴于上述问题， 我们经过反复研究， 曾提出过一种克服上述问题的解决方案 （参见 CN1026403C, CN1040199C 号中国专利文献）， 即采用一种双层复合球团直接还原磷矿石生产 磷酸的工艺， 具体技术解决方案是： 先将磷矿石与配入物料制成球团， 在回转窑内， 球团中 的 P205被还原成磷蒸气并挥发， 在料层上方， 磷蒸气被引入炉内的空气氧化成 P205气体， 然 后在水化装置中被吸收制得磷酸。 该技术方案的最大特点在于： 配入的物料球团采用双层复 合结构， 其内层是由磷矿石、 硅石 （或石灰、 石灰石等） 和碳质还原剂经磨碎、 混匀后造球 而成， 其外层是在内层球团上再裹上一层含碳量大于 20%的固体燃料， 球团的内、 外层配料 时添加粘结剂， 球团采用干燥固结。 球团内层 Ca0/Si02摩尔比可以小于 0. 6或大于 6. 5， 碳 质还原剂为还原磷矿石理论量的 1〜3倍，球团外层固体燃料配量可以为内层球团质量的 5%〜 25%； 球团内、 外层添加的粘结剂可以是沥青、 腐植酸钠、 腐植酸铵、 水玻璃、 亚硫酸盐纸浆 废液、糖浆、木质素磺酸盐中的一种或多种的组合，其添加量为被添加物料重量的 0. 2%〜15% (干基）。 该球团可以采用干燥固结， 固结温度为 80°C〜600°C， 固结时间为 3min〜120min。
我们提出的上述方法采用在球团上裹一层含固体碳的耐高温包裹料，包裹时添加粘结剂， 以使外层包裹料能良好地附着在内层球团上。 将这种双层复合球团经干燥固结后送入回转窑 中， 在回转窑高温带 （1300°C〜140(TC左右） 可以很好地实现磷矿石的碳热还原。 由于在料 球表面人为包覆了一层含固体还原剂 （碳质物料） 的包裹层， 该包裹层可将其内层球团与回 转窑料层上部的含 02和 P205的气流氧化区进行有效地物理隔离。 当这种复合球团在回转窑固 体料层中随回转窑的旋转运动上升到回转窑固体料层表面， 并与回转窑固体料层上部的含 02 和 P205的气流氧化区接触发生对流传质时， 包裹层中的碳便可与氧化区中的 02发生有限的氧 化反应 （因在工业大型回转窑中料球暴露在回转窑料层表面的时间较短， 反应不完全）， 使 02不能传递到内层球团， 保证了内层球团中的还原剂碳不被回转窑气流中的氧所氧化， 使磷 矿石中 P205的还原过程能进行彻底， 实现了工艺过程中磷矿 P205的高还原率。 另一方面， 回 转窑料层上部气流氧化区中的 P205也不可能与复合球团表层包裹层中的碳反应， 因而阻止了 在复合球团上形成磷酸盐或偏磷酸盐化合物， 消除了原有 KPA工艺料球上富含 P205白壳的生 成， 确保了工艺可获得较高的 P2O5收率。 与此同时， 该方法中以固体燃料取代或部分取代了 气体或液体燃料， 这可进一步降低磷酸的生产成本。
此外， 我们提出的上述方法中在造球时还加入了有机粘结剂， 这可使复合球团在干燥脱 水后 （低于球团中碳氧化温度）， 仍可以达到 200kN/个球以上的抗压强度和 10次 /米以上的 落下强度， 因此， 该复合球团可以抵抗在回转窑内受到的机械摩擦力而不被粉碎， 克服了原 有 KPA工艺存在的球团强度差等缺陷， 也克服了球团中碳在回转窑预热带过早氧化的现象， 使复合球团在窑内不出现粉化， 进而避免了粉料造成的回转窑高温结圈致使工艺失败， 保证 了工艺能在设定的条件下顺利进行。
然而， 在我们后续的研究过程中， 又发现了一系列新的技术问题， 这其中就有部分技术 问题体现在窑法磷酸工艺的水化吸磷及氟回收阶段。 窑法磷酸的水化收酸工艺以前主要是借 鉴热法磷酸收酸的方法， 但窑法磷酸的出窑烟气与热法磷酸黄磷燃烧后的烟气存在很大的不 同： 其一， 出窑烟气中 P205的浓度较低， 相同规模产量的烟气量前者是后者的 3〜4倍； 其二， 窑法磷酸的出窑烟气成分复杂， 含氟、 尘、 302等杂质。 因此， 如果仍旧沿用传统的热法磷酸 的收酸方法则会存在较多问题： 首先， 热法磷酸的烟气量小， 相应设备的烟气流速低， 如果 直接套用到窑法磷酸工艺上， 则设备***的尺寸会相当庞大， 该设备***不仅结构复杂， 而 且投资和运行成本均较高； 其次， 窑法磷酸的烟气杂质含量复杂， 喷淋酸的腐蚀性更强， 要 防止酸中固体杂质对设备和管道的堵塞， 其收酸工艺和设备结构都需要做进一步的改进； 更 重要的是， 窑法磷酸出窑烟气还含有对人体有害的含氟物质 （以 SiF^P HF形态存在）， 这需 要加以回收利用， 同时避免对环境的污染。
因此， 为了降低窑法磷酸工艺的生产成本和运行费用， 保证产品磷酸质量， 充分利用资 源， 避免环境污染， 对窑法磷酸工艺的氟回收设备及氟回收工艺还需要本领域技术人员进行 更深入的研究， 以提出更切合实际的解决方案。
【发明内容】
本发明要解决的技术问题是克服现有技术的不足， 提供一种结构简单、 布局合理、 投资 成本低、 适应性强、 原料利用率高、 可减少污染物排放、 氟回收效果好的用于从窑法磷酸工 艺水化吸磷后的烟气中回收氟的设备， 以及利用该设备回收氟的工艺方法。
为解决上述技术问题， 本发明提出的技术方案为一种用于从窑法磷酸工艺水化吸磷后的 烟气中回收氟的设备， 该设备包括一级氟吸收塔和二级氟吸收塔， 所述一级氟吸收塔和二级 氟吸收塔均为流态化逆流式洗涤塔，一级氟吸收塔主要由氟硅酸洗涤管和氟硅酸分离罐组成， 氟硅酸洗涤管的进口连通至水化吸磷后的烟气的输送管道， 氟硅酸洗涤管的出口连通至氟硅 酸分离罐的中部， 氟硅酸分离罐的顶部设有烟气出口， 底部设有氟硅酸液出口， 该氟硅酸液 出口通过一带循环泵的循环输送管道与所述氟硅酸洗涤管内的喷嘴相连通； 所述二级氟吸收塔主要由二级氟硅酸洗涤管和二级氟硅酸分离罐组成， 所述一级氟吸收 塔的烟气出口通过管道连接至二级氟硅酸洗涤管， 二级氟硅酸洗涤管的出口连通至二级氟硅 酸分离罐的中部， 二级氟硅酸分离罐的顶部设有除沫层和烟气出口， 底部设有氟硅酸液出口， 该氟硅酸液出口通过一带循环泵的循环输送管道与二级氟硅酸洗涤管内的喷嘴和一级氟吸收 塔的氟硅酸分离罐相连通。
上述的回收氟的设备中， 所述一级氟吸收塔和二级氟吸收塔的吸氟原理主要表现为： 在 逆喷式的氟硅酸洗涤管中向下流动的水化吸磷后的烟气与向上喷射的循环浓氟硅酸溶液相 撞， 从而迫使液体呈辐射状自里向外射向管壁， 这样在气-液界面处建立起一定高度的泡沫区 (泡沫柱）， 该泡沫柱根据气液的相对动量的变化沿管体上下移动， 由于气体与大面积不断更 新的液体表面接触， 在泡沫区发生粒子的捕集及气体的吸收， 并相应进行热量的传递。
上述的回收氟的设备中， 优选的， 所述二级氟吸收塔中的循环输送管道上还设有氟硅酸 冷却器， 氟硅酸冷却器的出液口分成两路， 一路与所述二级氟硅酸洗涤管内的喷嘴相连通， 另一路与二级氟硅酸分离罐顶部的喷淋层连通。
上述的回收氟的设备中， 优选的， 所述二级氟吸收塔的烟气出口还连接至一尾吸塔， 该 尾吸塔为一喷淋空塔， 尾吸塔的顶部设有烟气出口， 塔内上方设有喷淋层， 底部设有碱吸收 液箱， 该碱吸收液箱的出口通过带循环泵的循环输送管道与尾吸塔内的喷淋层相连通。
作为一个总的技术构思， 本发明还提供一种用上述本发明的设备从窑法磷酸工艺水化吸 磷后的烟气中回收氟的工艺， 包括以下步骤：
( 1 )一级氟吸收： 先将水化吸磷后的烟气输送至所述一级氟吸收塔的氟硅酸洗涤管， 烟 气自上而下与喷嘴自下而上喷入的循环氟硅酸溶液发生充分的气液两相接触， 并进行传质传 热和化学反应（烟气中的氟（主要是四氟化硅）与循环氟硅酸溶液中的水发生反应）， 反应生 成氟硅酸，同时烟气中的热焓通过绝热蒸发循环氟硅酸溶液中的水分被部分转移到水蒸气中；
( 2 )一级气液分离： 所述氟硅酸洗涤管中的气体和液体全部转移至氟硅酸分离罐中进行 气液分离， 分离后的气体通过一级氟吸收塔的烟气出口进入所述二级氟吸收塔的二级氟硅酸 洗涤管中， 分离后的液体留存于氟硅酸分离罐中并通过带循环泵的循环输送管道回送至氟硅 酸洗涤管中进行上述步骤 （1 ) 的操作；
( 3 )二级氟吸收： 进入二级氟硅酸洗涤管中的烟气自上而下与喷嘴自下而上喷入的循环 氟硅酸溶液发生充分的气液两相接触， 并进行传质传热和化学反应， 反应生成氟硅酸， 同时 烟气中的热焓通过热量传递部分转移到循环氟硅酸溶液中；
( 4)二级气液分离： 所述二级氟硅酸洗涤管中的气体和液体全部转移至二级氟硅酸分离 罐中进行气液分离，分离后的气体通过二级氟吸收塔的烟气出口进入后续的尾吸塔进行处理， 分离后的液体留存于二级氟硅酸分离罐中， 部分通过循环泵回送至二级氟硅酸洗涤管中进行 上述步骤 （3 ) 的操作， 部分输送到一级氟吸收塔的氟硅酸分离罐中；
( 5 )所述一级氟吸收塔中的氟硅酸溶液会不断增加， 多出的氟硅酸溶液经过滤去硅胶后 后作为副产的氟硅酸产品。
上述的工艺中， 优选的， 所述步骤（1 ) 中， 一级氟吸收采用的循环氟硅酸溶液的质量浓 度为 8%〜25%(更优选 10%〜20%)，循环氟硅酸溶液的温度为 25 °C〜65 °C (更优选 50 °C〜65 °C )， 喷淋液气比控制在 3L/m3〜25L/m3 (更优选 3L/m3〜6L/m3 ) ; 所述步骤 （3 ) 中， 二级氟吸收采 用的循环氟硅酸溶液的质量浓度为 0. 5%〜5%， 循环氟硅酸溶液的温度为 25 °C〜60 °C (更优选 45 °C〜60 °C )， 喷淋液气比控制在 3L/m3〜25L/m3 (更优选 3L/m3〜6L/m3)。
上述的工艺中， 优选的， 所述步骤（3 ) 中， 进入二级氟硅酸洗涤管的循环氟硅酸溶液经 过了氟硅酸冷却器的冷却处理， 经步骤 （3 ) 处理后的烟气的温度降至 60 °C以下。
上述的工艺中， 优选的， 所述水化吸磷后的烟气是通过一制磷酸***水化吸收后获得， 所述制磷酸***包括水化塔、 酸液循环喷淋***、 磷酸雾捕集塔和除雾分离塔；
所述水化塔的本体为一喷淋空塔， 所述水化塔的下部设有出回转窑烟气的烟气进口， 顶 部设有烟气出口， 所述烟气进口上方的水化塔容腔中设有喷淋装置， 所述酸液循环喷淋*** 的进液口设于水化塔的底部， 酸液循环喷淋***的出液口连接至所述喷淋装置的进液管， 所 述酸液循环喷淋***中还设有酸液储液槽和循环泵；
所述磷酸雾捕集塔为流态化逆流式洗涤塔， 其主要由洗涤管和分离罐组成， 所述水化塔 的烟气出口通过管道与该洗涤管的进口相连通， 洗涤管的出口连通至分离罐的中部， 分离罐 的顶部设有烟气出口， 底部设有酸液出口， 该酸液出口通过一带循环泵的循环输送管道与洗 涤管内的喷嘴相连通；
所述磷酸雾捕集塔的烟气出口通过管道与所述除雾分离塔的下部相连通， 除雾分离塔中 设在线水冲洗装置， 除雾分离塔的顶部设有烟气出口以排出水化吸磷后的烟气， 底部设有酸 液出口， 该酸液出口通过管道与磷酸雾捕集塔的酸液进口相连通。
上述的工艺中， 优选的， 所述水化塔配备有冷却***， 所述冷却***包括以下结构中的 a禾口 /或 b :
a， 所述水化塔的容腔外壁包覆设有水冷***；
b， 所述酸液循环喷淋***中靠近其进液口的位置设有酸冷器。
上述的工艺中， 优选的， 所述除雾分离塔的上部安装有丝网除雾器， 下部设计成类似旋 风除尘器的磷酸液滴收捕结构， 所述在线水冲洗装置安装在丝网除雾器上方。
上述的工艺中， 优选的， 所述喷淋装置包括至少两个位于水化塔容腔不同高度处的喷淋 层， 且至少两个的喷淋层中包含稀磷酸喷淋层和浓磷酸喷淋层， 浓磷酸喷淋层设于稀磷酸喷 淋层上方； 所述浓磷酸喷淋层的进液管与所述酸液循环喷淋***相连通， 所述稀磷酸喷淋层 的进液管与磷酸雾捕集塔的循环输送管道相连通； 所述酸液循环喷淋***中循环泵后的输送 管道上通过一支管与所述磷酸雾捕集塔的酸液进口相连通。
与现有技术相比， 本发明的优点在于：
( 1 )本发明的回收氟的设备对现有的回收氟的设备的结构和连接关系做了大量改进和优 化， 使得整个设备的结构更加简化、 合理， 能更好地配合水化吸收磷酸的工艺路线需要， 并 可根据工艺过程对经济性、 环保性、 投资成本等具体要求调整和优化设备的集成性能， 具有 更强的适应性；
( 2 )在实现相同功能和达到相同效果的前提下， 本发明的回收氟的设备大幅简化了*** 结构， 降低了设备的投资、 运行和维护费用；
( 3 )本发明优选的技术方案中通过对水化吸磷后的烟气原料制备来源进行优化限定， 可 以实现窑法磷酸工艺出窑烟气中 P205和氟的同时回收， 实现水化吸收磷和回收氟前后工序的 有效配合， 进而得到价值较高的主产品磷酸和副产品氟硅酸， 使得原料资源得到了更充分的 利用， 提高了窑法磷酸工艺的经济效益；
( 4)本发明优选的技术方案几乎实现了工艺过程废气、 废料、 废液的零排放， 使得整个 工艺的环保性大大提高；
( 5 )本发明的设备完全可适用于低品位磷矿直接生产磷酸， 对于我国大量低品位磷矿的 有效利用具有十分重要的意义。
【附图说明】
图 1为本发明具体实施方式中氟回收设备的结构示意图。
图 2为本发明具体实施方式中氟回收工艺的流程图。
图 3为本发明具体实施方式中制磷酸***的结构示意图。
图 4为本发明具体实施方式中制磷酸设备的水化塔结构示意放大图。
图 5为本发明具体实施方式中制磷酸设备的磷酸雾捕集塔结构示意放大图。
图例说明：
1、 水化塔； 11、 烟气进口； 12、 烟气出口； 13、 喷淋装置； 14、 进液口； 15、 出液口； 16、 酸液储液槽； 17、 水冷***； 18、 酸冷器； 2、 循环泵； 21、 压滤装置； 22、 填料过滤装 置； 23、 磷酸精制设备； 24、 浓磷酸喷淋层； 25、 稀磷酸喷淋层； 3、 磷酸雾捕集塔； 31、 洗 涤管； 32、 分离罐； 33、 酸液出口； 34、 酸液进口； 35、 喷嘴； 4、 除雾分离塔； 41、 在线水 冲洗装置； 42、 丝网除雾器； 43、 磷酸液滴收捕结构； 5、 一级氟吸收塔； 51、 氟硅酸洗涤管； 52、 氟硅酸分离罐； 53、 氟硅酸液出口； 54、 氟硅酸精制设备； 6、 二级氟吸收塔； 61、 二级 氟硅酸洗涤管； 62、 二级氟硅酸分离罐； 63、 氟硅酸冷却器； 7、 尾吸塔； 8、 风机。
【具体实施方式】
以下结合说明书附图和具体优选的实施例对本发明作进一步描述， 但并不因此而限制本 发明的保护范围。
实施例：
一种如图 1所示本发明的用于从窑法磷酸工艺水化吸磷后的烟气中回收氟的设备， 包括 一级氟吸收塔 5和二级氟吸收塔 6。 一级氟吸收塔 5和二级氟吸收塔 6均采用流态化逆流式 洗涤塔。 一级氟吸收塔 5主要由氟硅酸洗涤管 51和氟硅酸分离罐 52组成， 氟硅酸洗涤管 51 的进口连通至水化吸磷后的烟气的输送管道， 氟硅酸洗涤管 51 的出口连通至氟硅酸分离罐 52的中部， 氟硅酸分离罐 52的顶部设有烟气出口 12， 底部设有氟硅酸液出口 53， 该氟硅酸 液出口 53通过一带循环泵 2的循环输送管道与氟硅酸洗涤管 51内的喷嘴 35相连通，氟硅酸 分离罐 52则兼做循环输送管道的酸循环槽。
本实施例中二级氟吸收塔 6的结构与一级氟吸收塔 5相似， 二级氟吸收塔 6主要由二级 氟硅酸洗涤管 61和二级氟硅酸分离罐 62组成，一级氟吸收塔 5的烟气出口 12通过管道与二 级氟硅酸洗涤管 61的进口连通，二级氟硅酸洗涤管 61的出口连通至二级氟硅酸分离罐 62的 中部， 二级氟硅酸分离罐 62的顶部设有除沫层和烟气出口 12， 底部设有氟硅酸液出口 53， 该氟硅酸液出口 53通过一带循环泵 2的循环输送管道与二级氟硅酸洗涤管 61内的喷嘴 35相 连通。
本实施例中， 二级氟吸收塔 6的循环输送管道上还设有氟硅酸冷却器 63， 氟硅酸冷却器
63的进口与循环泵 2相连， 出口则分成两路， 一路与二级氟硅酸洗涤管 61内的喷嘴 35相连 通， 另一路与二级氟硅酸分离罐 62顶部的喷淋层连通， 二级氟硅酸分离罐 62同样兼做循环 输送管道的酸循环槽。 二级氟吸收塔 6的循环泵 2出口还通过支管与一级氟吸收塔 5的氟硅 酸分离罐 52的进液口相连， 借此可将二级氟吸收塔 6多余的氟硅酸溶液串至一级氟吸收塔 5 内。
为实现全部污染物的达标排放， 在本实施例回收氟的设备最后还连接有尾吸塔 7， 该尾 吸塔 7为一喷淋空塔， 二级氟吸收塔 6的烟气出口 12通过管道与尾吸塔 7的烟气进口 11相 连通。 尾吸塔 7的顶部设有烟气出口 12， 塔内上方设有喷淋层， 底部设有碱吸收液箱 （氢氧 化钠）， 该碱吸收液箱出口通过带循环泵 2的循环输送管道与尾吸塔 7内各喷淋层相连， 进而 形成一个尾气吸收循环喷淋***。
上述的氟硅酸液出口 53另外通过带给料泵的管道与外部的氟硅酸精制设备 54 (或氟盐 加工设备） 连接， 在进入氟硅酸精制设备 54之前可通过压滤装置 21先进行压滤处理， 压滤 装置 21的溢流口再通过管道连接至氟硅酸精制设备 54。
一种如图 2所示用上述设备从窑法磷酸工艺水化吸磷后的烟气中回收氟的工艺， 包括以 下步骤：
( 1 ) 一级氟吸收： 先将水化吸磷后的烟气输送至一级氟吸收塔 5的氟硅酸洗涤管 51， 烟气中大部分的氟（主要是四氟化硅）自上而下与喷嘴 35自下而上喷入的循环氟硅酸溶液（质 量浓度为 10%〜20%， 温度为 25°C〜65°C， 喷淋液气比控制在 3L/m3〜25L/m3 ) 发生充分的气 液两相接触， 并进行传质传热和化学反应， 反应生成氟硅酸， 同时烟气中的热焓通过热量传 递大部分转移到循环氟硅酸溶液中； 烟气通过绝热蒸发循环氟硅酸溶液中的水分和传热给循 环氟硅酸溶液的方式被进一步降温到 50°C〜70°C ;
( 2 )—级气液分离： 在氟硅酸洗涤管 51中的气体和液体全部转移至氟硅酸分离罐 52中 进行气液分离， 分离后的气体通过一级氟吸收塔 5的烟气出口进入二级氟吸收塔 6的二级氟 硅酸洗涤管 61中， 分离后的液体留存于氟硅酸分离罐 52中并通过带循环泵 2的循环输送管 道回送至氟硅酸洗涤管 51中进行上述步骤 （1 ) 的操作；
( 3 ) 二级氟吸收： 进入二级氟硅酸洗涤管 61中的烟气 （剩余的绝大部分的含氟物质， 主要是四氟化硅） 自上而下与喷嘴 35 自下而上喷入的循环氟硅酸溶液 （质量浓度为 0. 5%〜 5%， 温度为 25°C〜60°C， 喷淋液气比控制在 3L/m3〜25L/m3 )发生充分的气液两相接触， 并进 行传质传热和化学反应， 反应生成氟硅酸， 同时烟气中的热焓通过热量传递部分转移到循环 氟硅酸溶液中； 经步骤 （3 ) 处理后的烟气的温度进一步降至 60°C以下；
( 4) 二级气液分离： 在二级氟硅酸洗涤管 61中的气体和液体全部转移至二级氟硅酸分 离罐 62中进行气液分离， 分离后的气体通过二级氟吸收塔 6的烟气出口进入后续的尾吸塔 7 进行处理，分离后的液体留存于二级氟硅酸分离罐 62中通过带循环泵 2的循环输送管道回送 至二级氟硅酸洗涤管 61中进行上述步骤 （3 ) 的操作， 该循环输送管道安装有氟硅酸冷却器 63， 进入二级氟硅酸洗涤管 61的循环氟硅酸溶液经过了氟硅酸冷却器 63的冷却处理； 多余 部分的循环氟硅酸溶液则直接排放到一级氟吸收塔 5的氟硅酸分离罐 52中；
( 5 ) 一级氟吸收塔 5和二级氟吸收塔 6中的循环氟硅酸溶液因吸收烟气中的氟有累积， 二级氟吸收塔 6中多余的循环氟硅酸溶液排放至一级氟吸收塔 5中， 最终一级氟吸收塔 5中 多余的循环氟硅酸溶液经给料泵送至压滤装置 21进行压滤，滤液去氟硅酸精制工序精制成氟 硅酸成品或加工成氟盐产品； 滤渣为硅胶， 洗净除杂后作为副产品。 进入后续尾吸塔 7进行 处理的烟气在尾吸塔 7的向上运动过程中与向下喷淋的循环吸收溶液进行逆流接触， 尾吸塔 7底部吸收液箱通过循环泵 2与塔内各喷淋层相连， 形成一个循环喷淋***； 为了保持吸收 液的吸收能力， 吸收液的 PH值保持在 8以上， 需要不断加入稀的碱溶液 （氢氧化钠溶液）， 而吸收液因稀的碱溶液的加入和烟气中 P205、 氟等杂质的吸收会有累积， 需要不断排出进行 污水处理， 处理回收的水可回用到窑法磷酸的原料工序； 烟气中剩余的污染物 （P205、 SiF4、 粉尘等） 被喷淋液吸收， 烟气得到进一步的洗涤净化， 达到国家排放标准， 然后通过引风机 排至烟囱排放。
上述工艺中， 水化吸磷后的烟气是通过一如图 3〜图 5所示的制磷酸***水化吸收后获 得， 该制磷酸***包括水化塔 1、 酸液循环喷淋***、 磷酸雾捕集塔 3和除雾分离塔 4。
本实施例的水化塔 1的本体为一喷淋空塔，水化塔 1的下部设有出窑烟气的烟气进口 11， 顶部设有经水化吸收后的烟气出口 12，烟气进口 11上方的水化塔 1容腔中设有喷淋装置 13， 酸液循环喷淋***的进液口 14设于水化塔 1的底部， 酸液循环喷淋***的出液口 15连接至 喷淋装置 13的进液管， 酸液循环喷淋***中还设有酸液储液槽 16和循环泵 2。 本实施例水 化塔 1的容腔外壁包覆设有水冷*** 17， 且水冷*** 17中的冷却水采用下进上出的方式。 另外， 在酸液循环喷淋***中靠近其进液口 14的位置设有酸冷器 18; 酸冷器 18的出口与酸 液储液槽 16的进口相连， 酸液储液槽 16的出口通过循环泵 2与喷淋装置 13的进液管相连， 进而形成一个酸液循环喷淋***。
本实施例的磷酸雾捕集塔 3为一个高效流态化逆流式洗涤塔，其主要由洗涤管 31和分离 罐 32组成， 水化塔 1的烟气出口 12通过管道与洗涤管 31的进口相连通， 洗涤管 31的出口 连通至分离罐 32的中部， 分离罐 32的顶部设有烟气出口 12， 底部设有酸液出口 33， 该酸液 出口 33通过一带循环泵 2的循环输送管道与洗涤管 31内的喷嘴 35相连通 （参见图 5)， 分 离罐 32同时作为磷酸雾捕集塔 3中循环输送管道的酸循环槽。
为了实现水化塔 1与磷酸雾捕集塔 3相互串酸，本实施例中水化塔 1的喷淋装置 13设有 三个位于水化塔 1容腔不同高度处的喷淋层，且三个喷淋层中包含一个稀磷酸喷淋层 25和两 个浓磷酸喷淋层 24 (参见图 4)， 两个浓磷酸喷淋层 24设于稀磷酸喷淋层 25上方； 浓磷酸喷 淋层 24的进液管与上述水化塔 1的酸液循环喷淋***相连通， 稀磷酸喷淋层 25的进液管则 与磷酸雾捕集塔 3的循环输送管道相连通， 这样首先实现了磷酸雾捕集塔 3中的酸液串至水 化塔 1。 另外， 在上述酸液循环喷淋***中循环泵 2后的输送管道上通过一支管连接至磷酸 雾捕集塔 3的酸液进口 34处。但考虑与后续磷酸的过滤、精制工序相衔接， 该支管上设有一 填料过滤装置 22， 填料过滤装置 22的进酸口通过支管连通至酸液循环喷淋***， 填料过滤 装置 22的滤液出口则分成三路， 一路连通至磷酸雾捕集塔 3的酸液进口 34， 一路连通至外 部的磷酸精制设备 23， 另一路则连通至酸液储液槽 16; 填料过滤装置 22的底流出口则通过 管道连接至压滤装置 21的进料口， 压滤装置 21的溢流口通过管道与酸液循环喷淋***中的 酸液储液槽 16连通， 以充分实现磷酸的回收利用， 保证磷酸的高收率。
本实施例中， 磷酸雾捕集塔 3的烟气出口 12通过管道与除雾分离塔 4的下部相连通， 除 雾分离塔 4的顶部设有烟气出口 12排出水化吸磷后的烟气， 底部设有酸液出口 33， 该酸液 出口 33通过管道与磷酸雾捕集塔 3的酸液进口 34相连通。 除雾分离塔 4中设在线水冲洗装 置 41， 在线水冲洗装置 41加入的水同时可作为整个水化吸收制磷酸工序的补水， 并通过管 道逐级返补至上游的磷酸雾捕集塔 3及水化塔 1中。 除雾分离塔 4的上部安装有丝网除雾器 42， 下部设计成类似旋风除尘器的磷酸液滴收捕结构 43， 在线水冲洗装置 41安装在丝网除 雾器 42上方。
本实施例中上述制磷酸***的工作原理如下：
1、 水化塔中 P205的水化吸收：
将含 P205和氟的烟气（特例为 KPA窑法磷酸工艺中 500°C以上的出窑烟气，含 P20580g/Nm3 ) 由水化塔 1下部的烟气进口 11通入塔内， 此前开启酸液循环喷淋***的循环泵 2， 使水化塔 1中的浓磷酸溶液通过上、 中两层浓磷酸喷淋层 24喷出， 最上层浓磷酸喷淋层 24的部分喷 嘴从斜下方喷向塔内壁， 其余喷嘴垂直向下喷出， 中、 下两层喷淋层的喷嘴垂直向下喷淋， 喷淋的浓磷酸溶液与进入塔内的含 P205和氟的烟气逆流充分接触， 进行传质传热， 烟气中的 P205与喷淋的浓磷酸溶液中的水发生化学反应生成磷酸， 生成的磷酸一半以上被吸收进喷淋 液， 其余部分形成磷酸雾保持在气相中， 而烟气中的氟（例如 SiF^P HF等）在浓磷酸和较高 温度条件下， 很难被吸收进喷淋液中； 烟气通过与循环喷淋的较低温浓磷酸溶液换热以及水 化塔 1内水冷*** 17的冷却， 温度降至 75°C〜130°C， 出水化塔 1的循环浓磷酸溶液温度则 被提高到 70°C〜95°C。 根据烟气中水分的含量大小， 循环喷淋的浓磷酸溶液的质量百分比浓 度可选择在 60%〜90%的范围内 （本实施例采用 70%〜85%浓度的磷酸溶液）， 水化塔内浓磷酸 溶液的进塔温度控制为 50°C〜8(TC， 喷淋液气比控制在 3L/m3〜20L/m3。在出塔烟气中夹带有 较多以雾状形态存在磷酸雾， 不能在水化塔 1 中沉降下来， 随烟气一起被带出水化塔 1。 该 水化塔 1具有冷却烟气和水化吸收 P205的双重功能， 其中主要发生的化学反应如下。
P205 + 3H20 = 2¾P04
水化塔 1中喷淋落下的浓磷酸溶液最后通过进液口 14进入酸液循环喷淋***，然后流入 酸冷器 18中， 酸冷器 18的结构为一个搅拌槽中布置有若干不锈钢管环成的换热板， 管中通 入循环冷却水， 通过搅拌， 使进入酸冷器 18的磷酸溶液在换热板上形成强制对流换热， 提高 传热效率， 将浓磷酸中的热焓部分转移到酸冷器 18的循环冷却水中， 通过冷却水将循环浓磷 酸溶液的热量不断转移。 从酸冷器 18出口流出的循环酸液进入酸液储液槽 16， 并通过循环 泵 2再次回送到上、 中两层浓磷酸喷淋层 24的各个喷嘴进行循环喷淋。 2、 磷酸雾捕集塔中磷酸雾的捕集：
由水化塔 1顶部烟气出口 12排出的气相物质 （即烟气） 进入磷酸雾捕集塔 3的洗涤管 31 中， 该塔为一台流态化逆流洗涤塔， 在洗涤管 31 中由下向上喷射循环稀磷酸溶液， 稀磷 酸溶液与由上向下的高速烟气流碰撞接触后在气 -液界面区域形成强烈的湍动区域，流体动量 达到平衡后建立起一定高度的稳定的泡沫区（泡沫柱）， 烟气穿过泡沫区， 与大面积不断更新 的磷酸溶液液体表面接触， 在泡沫区发生粒子的捕集、 聚合长大和热量的传递， 烟气中夹带 的磷酸雾绝大部分转入循环稀磷酸溶液， 吸收区内烟气表观流速为 10m/S〜30m/s， 液气比为 3L/m3〜25L/m3。烟气通过绝热蒸发循环稀磷酸溶液中水分的方式被进一步降温到 60 °C〜75 °C。 与传统热法磷酸文丘里除雾器相比， 在同样的除雾效果情况下， 本发明的磷酸雾捕集塔可大 大减少设备的动力压头损失， 降低收酸装置能耗。
磷酸雾捕集塔 3中循环喷淋的酸液采用 10%〜50%质量浓度的稀磷酸溶液， 洗涤管 31中 的气体和液体进入塔下部的分离罐 32中进行气-液分离， 循环酸液落入分离罐 32底部， 该塔 的分离罐 32同时兼作循环酸槽， 底部的稀磷酸溶液再通过循环泵 2回送至洗涤管 31或者根 据需要串酸至水化塔 1的稀磷酸喷淋层 25中。
3、 除雾分离塔中磷酸雾的捕集：
从磷酸雾捕集塔 3中烟气出口 12排出的烟气再进入到除雾分离塔 4中进行进一步的气- 液分离， 以进一步除去烟气中的磷酸雾， 除雾分离塔下部设计成类似旋风除尘器的磷酸液滴 收捕结构 43， 利用离心力将已长大的磷酸液滴从烟气中捕集下来， 在除雾分离塔上部安装有 丝网除雾器 42， 将烟气中尚未长大的磷酸雾滴进一步捕集下来以保证设备对 P205的直收率； 除雾分离塔 4排出的水化吸磷后的烟气则送入氟回收设备中进行回收氟的处理。
由于磷酸的水化吸收过程化合烟气中 P205需要消耗水， 另外烟气降温过程中从喷淋酸液 中蒸发了部分水分， 因此水化吸收过程需要不断补充水， 本实施例工艺***中需要补充的水 量全部从除雾分离塔 4烟气出口 12处补入， 此时在线水冲洗装置 41不仅充当补水装置， 同 时兼做除雾分离塔 4上部丝网除雾器的冲洗装置。 由于全部的补水都加入到了除雾分离塔 4 中， 而除雾分离塔 4的底液又通过磷酸雾捕集塔 3的酸液进口 34回流至磷酸雾捕集塔 3中， 因此磷酸雾捕集塔 3中循环酸液浓度会逐步降低， 而另一方面， 水化塔 1中由于不断吸收烟 气中的 P205， 其中循环酸液浓度会逐渐增高， 因此， 水化塔 1和磷酸雾捕集塔 3的循环酸液 ***需要进行串酸， 以保持各自循环酸液浓度的稳定， 水化塔 1串至磷酸雾捕集塔 3的酸在 填料过滤装置 22中澄清、 过滤后引至磷酸雾捕集塔 3， 磷酸雾捕集塔 3串至水化塔 1的酸则 直接从磷酸雾捕集塔 3的循环泵 2出口处引出即可， 工艺***中多余的磷酸 （对应物料平衡 的产酸量）也从填料过滤装置 22上清液出口引出后进入精制工序， 加入活性碳、硅藻土及钡 盐， 脱去粗磷酸的颜色和 so4 2—然后用板框压滤机过滤， 提纯后得到浓磷酸成品。 此外， 烟气 中的尘等固体颗粒绝大部分转移到循环磷酸溶液后富集在填料过滤装置 22底流中，该底流定 期排出到压滤装置 21进行过滤， 滤液返回酸液储液槽 16， 滤渣排出***外部。

Claims

权 利 要 求
1、 一种用于从窑法磷酸工艺水化吸磷后的烟气中回收氟的设备， 其特征在于： 该设 备包括一级氟吸收塔和二级氟吸收塔， 所述一级氟吸收塔和二级氟吸收塔均为流态化逆流 式洗涤塔， 一级氟吸收塔主要由氟硅酸洗涤管和氟硅酸分离罐组成， 氟硅酸洗涤管的进口 连通至水化吸磷后的烟气的输送管道， 氟硅酸洗涤管的出口连通至氟硅酸分离罐的中部， 氟硅酸分离罐的顶部设有烟气出口， 底部设有氟硅酸液出口， 该氟硅酸液出口通过一带循 环泵的循环输送管道与所述氟硅酸洗涤管内的喷嘴相连通；
所述二级氟吸收塔主要由二级氟硅酸洗涤管和二级氟硅酸分离罐组成， 所述一级氟吸 收塔的烟气出口通过管道连接至二级氟硅酸洗涤管， 二级氟硅酸洗涤管的出口连通至二级 氟硅酸分离罐的中部， 二级氟硅酸分离罐的顶部设有除沫层和烟气出口， 底部设有氟硅酸 液出口， 该氟硅酸液出口通过一带循环泵的循环输送管道与二级氟硅酸洗涤管内的喷嘴和 一级氟吸收塔的氟硅酸分离罐相连通。
2、 根据权利要求 1 所述的回收氟的设备， 其特征在于： 所述二级氟吸收塔中的循环 输送管道上还设有氟硅酸冷却器， 氟硅酸冷却器的出液口与所述二级氟硅酸洗涤管内的喷 嘴和二级氟硅酸分离罐顶部的喷淋层相连通。
3、 根据权利要求 2所述的回收氟的设备， 其特征在于： 所述二级氟吸收塔的烟气出 口还连接至一尾吸塔， 该尾吸塔为一喷淋空塔， 尾吸塔的顶部设有烟气出口， 塔内上方设 有喷淋层， 底部设有碱吸收液箱， 该碱吸收液箱的出口通过带循环泵的循环输送管道与尾 吸塔内的喷淋层相连通。
4、 一种用权利要求 1〜3中任一项所述设备从窑法磷酸工艺水化吸磷后的烟气中回收 氟的工艺， 包括以下步骤：
( 1 ) 一级氟吸收： 先将水化吸磷后的烟气输送至所述一级氟吸收塔的氟硅酸洗涤管， 烟气自上而下与喷嘴自下而上喷入的循环氟硅酸溶液发生充分的气液两相接触， 并进行传 质传热和化学反应， 反应生成氟硅酸， 同时烟气中的热焓通过绝热蒸发循环氟硅酸溶液中 的水分被部分转移到水蒸气中；
( 2 ) 一级气液分离： 所述氟硅酸洗涤管中的气体和液体全部转移至氟硅酸分离罐中 进行气液分离， 分离后的气体通过一级氟吸收塔的烟气出口进入二级氟吸收塔的二级氟硅 酸洗涤管中， 分离后的液体留存于氟硅酸分离罐中并通过带循环泵的循环输送管道回送至 氟硅酸洗涤管中进行上述步骤 （1 ) 的操作； ( 3 ) 二级氟吸收： 进入二级氟硅酸洗涤管中的烟气自上而下与喷嘴自下而上喷入的 循环氟硅酸溶液发生充分的气液两相接触，并进行传质传热和化学反应，反应生成氟硅酸， 同时烟气中的热焓通过热量传递部分转移到循环氟硅酸溶液中；
( 4 ) 二级气液分离： 所述二级氟硅酸洗涤管中的气体和液体全部转移至二级氟硅酸 分离罐中进行气液分离， 分离后的气体通过二级氟吸收塔的烟气出口进入后续的尾吸塔进 行处理， 分离后的液体留存于二级氟硅酸分离罐中， 部分通过循环泵回送至二级氟硅酸洗 涤管中进行上述步骤 （3 ) 的操作， 部分输送到一级氟吸收塔的氟硅酸分离罐中；
( 5 ) 所述一级氟吸收塔中的氟硅酸溶液会不断增加， 多出的氟硅酸溶液经过滤去硅 胶后后作为副产的氟硅酸产品。
5、 根据权利要求 4所述的工艺， 其特征在于： 所述步骤 （1 ) 中， 一级氟吸收采用的 循环氟硅酸溶液的质量浓度为 8%〜25%， 循环氟硅酸溶液的温度为 25 °C〜65 °C， 喷淋液 气比控制在 3L/m3〜25L/m3; 所述步骤（3 ) 中， 二级氟吸收采用的循环氟硅酸溶液的质量 浓度为 0.5%〜5%， 循环氟硅酸溶液的温度为 25 °C〜60°C， 喷淋液气比控制在 3L/m3〜 25L/m3 0
6、 根据权利要求 4或 5所述的工艺， 其特征在于： 所述步骤 （3 ) 中， 进入二级氟硅 酸洗涤管的循环氟硅酸溶液经过了氟硅酸冷却器的冷却处理， 经步骤 （3 ) 处理后的烟气 的温度降至 60°C以下。
7、 根据权利要求 4或 5所述的工艺， 其特征在于： 所述水化吸磷后的烟气是通过一 制磷酸***水化吸收后获得， 所述制磷酸***包括水化塔、 酸液循环喷淋***、 磷酸雾捕 集塔和除雾分离塔；
所述水化塔的本体为一喷淋空塔， 所述水化塔的下部设有出回转窑烟气的烟气进口， 顶部设有烟气出口， 所述烟气进口上方的水化塔容腔中设有喷淋装置， 所述酸液循环喷淋 ***的进液口设于水化塔的底部， 酸液循环喷淋***的出液口连接至所述喷淋装置的进液 管， 所述酸液循环喷淋***中还设有酸液储液槽和循环泵；
所述磷酸雾捕集塔为流态化逆流式洗涤塔， 其主要由洗涤管和分离罐组成， 所述水化 塔的烟气出口通过管道与该洗涤管的进口相连通， 洗涤管的出口连通至分离罐的中部， 分 离罐的顶部设有烟气出口， 底部设有酸液出口， 该酸液出口通过一带循环泵的循环输送管 道与洗涤管内的喷嘴相连通；
所述磷酸雾捕集塔的烟气出口通过管道与所述除雾分离塔的下部相连通， 除雾分离塔 中设在线水冲洗装置， 除雾分离塔的顶部设有烟气出口用于排出水化吸磷后的烟气， 底部 设有酸液出口， 该酸液出口通过管道与磷酸雾捕集塔的酸液进口相连通。
8、 根据权利要求 7所述的工艺， 其特征在于： 所述水化塔配备有冷却***， 所述冷 却***包括以下结构中的 a和 /或 b:
a， 所述水化塔的容腔外壁包覆设有水冷***；
b， 所述酸液循环喷淋***中靠近其进液口的位置设有酸冷器。
9、 根据权利要求 7所述的工艺， 其特征在于： 所述除雾分离塔的上部安装有丝网除 雾器， 下部设计成类似旋风除尘器的磷酸液滴收捕结构， 所述在线水冲洗装置安装在丝网 除雾器上方。
10、 根据权利要求 7所述的工艺， 其特征在于： 所述喷淋装置包括至少两个位于水化 塔容腔不同高度处的喷淋层， 且至少两个的喷淋层中包含稀磷酸喷淋层和浓磷酸喷淋层， 浓磷酸喷淋层设于稀磷酸喷淋层上方； 所述浓磷酸喷淋层的进液管与所述酸液循环喷淋系 统相连通， 所述稀磷酸喷淋层的进液管与磷酸雾捕集塔的循环输送管道相连通； 所述酸液 循环喷淋***中循环泵后的输送管道上通过一支管与所述磷酸雾捕集塔的酸液进口相连 通。
PCT/CN2013/081135 2013-06-04 2013-08-09 用于从窑法磷酸工艺水化吸磷后的烟气中回收氟的设备及工艺 WO2014194564A1 (zh)

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