System and method for separating and purifying hydrogen chloride and hydrofluoric acid

Abstract

The invention discloses a system and a method for separating and purifying hydrogen chloride and hydrofluoric acid, belongs to the technical field of mixed gas separation, and aims to overcome the defects that a large amount of alkali liquor is consumed and the environment is influenced in the treatment of mixed gas of hydrogen chloride and hydrofluoric acid. The device comprises a sulfuric acid injection vacuum unit, a sulfuric acid absorption device and a sulfuric acid separation device, wherein sulfuric acid and mixed gas of hydrogen chloride and hydrofluoric acid are mixed in the sulfuric acid injection vacuum unit to absorb hydrofluoric acid to form mixed acid; mixed gas discharged from the sulfuric acid injection vacuum unit enters a sulfuric acid absorption device to be further mixed with sulfuric acid to absorb hydrofluoric acid to form mixed acid, and hydrogen chloride is separated and recycled; the sulfuric acid separation device separates the mixed acid to obtain sulfuric acid and hydrofluoric acid, the sulfuric acid flows back to the sulfuric acid injection vacuum unit and the sulfuric acid absorption device to be recycled, and the hydrofluoric acid is recycled. The hydrochloric acid and the hydrofluoric acid are recycled, so that the production cost is reduced, and no harmful waste is generated in the separation process.

Description

Technical Field

[0001] The invention relates to the technical field of mixed gas separation, and more specifically, to a system and method for separating and purifying hydrogen chloride and hydrofluoric acid. Background Art

[0002] At present, lithium hexafluorophosphate (LiPF6) is widely used as the main raw material for battery electrolysis, and more and more companies are producing lithium hexafluorophosphate. However, the mixed gas HCL and HF produced in the production process are absorbed into mixed waste acid, which becomes a waste that is difficult to dispose of, seriously affecting the cost and profit of the production company. In addition, the disposal of these mixed waste acids consumes a large amount of alkali liquid and other resources, and also seriously affects the environment and the occupational health of operators. This is also the difficulty encountered by many leading lithium hexafluorophosphate production companies and a problem that needs to be solved urgently. Summary of the invention

[0003] In order to overcome the above-mentioned shortcomings, the present invention provides a system and method for separating and purifying hydrogen chloride and hydrofluoric acid, which can separate the mixed gas of hydrogen chloride and hydrofluoric acid into hydrochloric acid and hydrofluoric acid, and the hydrochloric acid and hydrofluoric acid are recycled to reduce production costs. In addition, the separation process does not generate harmful waste, thus avoiding pollution to the environment.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solution: a system for separating and purifying hydrogen chloride and hydrofluoric acid, comprising: Sulfuric acid jet vacuum unit, in which the mixed gas of sulfuric acid, hydrogen chloride and hydrofluoric acid is mixed and absorbs hydrofluoric acid to form mixed acid; Sulfuric acid absorption device, the mixed gas discharged from the sulfuric acid injection vacuum unit enters the sulfuric acid absorption device and further mixes with sulfuric acid to absorb hydrofluoric acid to form mixed acid, and hydrogen chloride is separated and recovered; The sulfuric acid separation device separates the mixed acid into sulfuric acid and hydrofluoric acid. The sulfuric acid is refluxed to the sulfuric acid injection vacuum unit and the sulfuric acid absorption device for repeated use, and the hydrofluoric acid is recovered.

[0005] In this patent, sulfuric acid is used to first absorb the hydrofluoric acid in the mixed gas of hydrogen chloride and hydrofluoric acid, thereby separating the hydrogen chloride, and then recovering the hydrogen chloride. The mixed acid formed after sulfuric acid absorbs the hydrofluoric acid is separated by a sulfuric acid separation device, and the hydrofluoric acid gas can be separated after the mixed acid is heated, and the hydrofluoric acid is recovered, and the remaining is sulfuric acid, which is reused. After the mixed gas of hydrogen chloride and hydrofluoric acid passes through the hydrogen chloride and hydrofluoric acid separation and purification system, hydrogen chloride and hydrofluoric acid can be separated, and sulfuric acid is recycled in the entire system, achieving the purpose of greatly reducing production costs.

[0006] The sulfuric acid jet vacuum unit makes the front end system of the unit in a negative pressure state and the rear end of the unit in a positive pressure state, so that the gas phase can be transported and flowed normally. At the same time, the venturi tube of the unit can achieve the effect of mixing and absorption. Under the condition of sulfuric acid spraying, the sulfuric acid absorption device performs secondary mixing to achieve the purpose of complete separation of HF and HCL. After sulfuric acid is mixed with the mixed gas, HF is absorbed to form mixed acid. After the mixed acid is heated in the sulfuric acid separation device, HF gas can be separated, and the remaining sulfuric acid is refluxed to the sulfuric acid jet vacuum unit and the sulfuric acid absorption device for reuse.

[0007] The hydrogen chloride and hydrofluoric acid separation and purification system of the patent application can separate the hydrogen chloride and hydrofluoric acid mixed gas into hydrochloric acid and hydrofluoric acid. The hydrochloric acid and hydrofluoric acid are recycled to reduce production costs, and the separation process does not generate harmful waste, avoiding pollution to the environment.

[0008] Preferably, the sulfuric acid absorption device comprises an upper spray cylinder and a lower mixed acid storage cylinder, and a sulfuric acid spray pipe is installed in the spray cylinder.

[0009] The sulfuric acid spray pipe sprays sulfuric acid into the spray cylinder, and the mixed gas transported from the sulfuric acid spray vacuum unit to the spray cylinder mixes with the sprayed sulfuric acid. The sulfuric acid further absorbs the hydrofluoric acid in the mixed gas, thereby completely separating the hydrogen chloride, and the mixed acid falls into the mixed acid storage cylinder.

[0010] Preferably, the sulfuric acid separation device comprises a separation tank and a heat exchanger, wherein the inlet end of the heat exchanger is connected to the bottom of the separation tank, and the outlet end of the heat exchanger is connected to the top of the separation tank.

[0011] The heat exchanger heats the mixed acid in the separation tank, thereby separating the hydrofluoric acid in the gas phase.

[0012] Preferably, a primary dispersion disk and a secondary dispersion packing section are installed in the separation tank, a plurality of flow pipes are evenly arranged on the primary dispersion disk, and the upper ends of the flow pipes are higher than the primary dispersion disk.

[0013] After the mixed acid is transported to the separation tank, it first falls onto the primary dispersion plate. When the liquid level is higher than the upper opening of the flow tube, it flows down from the flow tube. This process can disperse the mixed acid and is conducive to separating the gas phase hydrofluoric acid. The secondary dispersion filler section further disperses the mixed acid and further improves the separation effect of gas phase hydrofluoric acid.

[0014] Preferably, the separation tank is connected to the vacuum unit via a pipeline.

[0015] The vacuum unit evacuates the separation tank, thereby reducing the temperature required for separation of gaseous hydrofluoric acid and preventing excessive temperature from affecting the corrosion resistance of the separation tank.

[0016] Preferably, the separation tank is connected to the mixed acid transfer tank and the sulfuric acid storage tank through pipelines, the mixed acid transfer tank is connected to the sulfuric acid injection vacuum unit through the mixed acid pipe, and the sulfuric acid storage tank is connected to the sulfuric acid absorption device through the acid delivery pipe.

[0017] The mixed acid transfer tank is used to store the mixed acid, and the sulfuric acid storage tank is used to store the separated sulfuric acid.

[0018] Preferably, the sulfuric acid separation device is connected to the hydrofluoric acid recovery device through a hydrofluoric acid recovery pipe. The hydrofluoric acid recovery device includes a condenser and a hydrofluoric acid receiving tank. The condenser is connected between the hydrofluoric acid recovery pipe and the hydrofluoric acid receiving tank.

[0019] The separated gaseous hydrofluoric acid is converted into liquid phase after passing through a condenser and flows into a hydrofluoric acid receiving tank for collection.

[0020] Preferably, the sulfuric acid absorption device is connected to the hydrogen chloride falling film water absorption device through a hydrogen chloride recovery pipe.

[0021] The separated gaseous hydrogen chloride passes through a hydrogen chloride falling film water absorption device, and after contacting and mixing with water, forms a hydrochloric acid solution, which is convenient for collection and utilization.

[0022] Preferably, the sulfuric acid injection vacuum unit includes a mixing tank and a venturi injection pipe, the mixing tank is connected to a secondary mixing mechanism, the secondary mixing mechanism includes an acid adding chamber and a gas mixing chamber, the acid adding chamber is connected to the sulfuric acid absorption device through the acid adding pipe, the gas mixing chamber is connected to the injection port of the venturi injection pipe, the lower widths of the acid adding chamber and the gas mixing chamber are gradually reduced from top to bottom so that a water curtain notch is formed at the lower opening end, and the center lines of the two water curtain notches intersect below the water curtain notch.

[0023] After sulfuric acid and mixed gas are mixed in the venturi injection pipe, they are injected into the gas mixing chamber from the injection port, and sprayed out from the water curtain slot at the lower end of the gas mixing chamber to form a gas-water mixed curtain. In the process of forming the gas-water mixed curtain, the mixing effect of the mixed gas and sulfuric acid can be improved, thereby improving the absorption effect of sulfuric acid on hydrofluoric acid. Sulfuric acid is transported to the acid adding chamber from the acid adding pipe, and sprayed out from the water curtain slot at the lower end of the acid adding chamber to form a water curtain. Since the center lines of the two water curtain slots intersect below the water curtain slot, the gas-water mixed curtain sprayed from the two water curtain slots and the water curtain will collide together, further achieving the mixing of sulfuric acid and mixed gas, improving the mixing effect, and improving the absorption effect of sulfuric acid on hydrofluoric acid.

[0024] A method for separating and purifying hydrogen chloride and hydrofluoric acid is operated by a hydrogen chloride and hydrofluoric acid separation and purification system, comprising the following steps: S1, a mixed gas of hydrogen chloride and hydrofluoric acid is transported to a sulfuric acid jet vacuum unit to be mixed with sulfuric acid, the sulfuric acid absorbs hydrofluoric acid to form a mixed acid, which is transported to a sulfuric acid separation device; S2, the mixed gas output by the sulfuric acid jet vacuum unit enters a sulfuric acid absorption device to be further mixed with sulfuric acid to absorb hydrofluoric acid to form a mixed acid, which is transported to a sulfuric acid separation device, and the separated hydrogen chloride is recovered; S3, the mixed acid is decomposed in the sulfuric acid separation device to obtain sulfuric acid and hydrofluoric acid, the sulfuric acid is refluxed to the sulfuric acid jet vacuum unit and the sulfuric acid absorption device for repeated use, and the hydrofluoric acid is recovered.

[0025] Sulfuric acid is mixed with a mixed gas of hydrogen chloride and hydrofluoric acid. The sulfuric acid can absorb hydrofluoric acid to form a mixed acid, thereby separating the gaseous hydrogen chloride. For the mixed acid formed by the mixture of sulfuric acid and hydrofluoric acid, the gaseous hydrogen fluoride can be separated by heating. The separated sulfuric acid is returned to the system and used as a medium without being consumed. The separated hydrogen chloride and hydrogen fluoride can be recycled, reducing production costs. In addition, the separation process does not generate harmful waste, avoiding pollution to the environment.

[0026] Compared with the prior art, the present invention has the following beneficial effects: (1) the hydrogen chloride and hydrofluoric acid separation and purification system of the present patent application can separate the hydrogen chloride and hydrofluoric acid mixed gas into hydrochloric acid and hydrofluoric acid, and the recycling of hydrochloric acid and hydrofluoric acid reduces production costs. In addition, the separation process does not generate harmful waste, thus avoiding environmental pollution; (2) the separated sulfuric acid is returned to the system and used as a medium without being consumed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the present invention.

[0028] Figure 2 It is a structural schematic diagram of the separation tank of the present invention.

[0029] Figure 3 It is a structural diagram of the secondary mixing mechanism of Example 2 of the present invention.

[0030] Figure 4 It is a structural diagram of the secondary mixing mechanism of Example 3 of the present invention.

[0031] In the figure: 1, sulfuric acid injection vacuum unit, 2, sulfuric acid absorption device, 3, sulfuric acid separation device, 4, mixing tank, 5, venturi injection pipe, 6, acid delivery pipe, 7, acid delivery pump, 8, secondary mixing mechanism, 9, acid addition chamber, 10, gas mixing chamber, 11, water curtain slot, 12, gas delivery pipe, 13, spray cylinder, 14, mixed acid storage cylinder, 15, sulfuric acid spray pipe, 16, hydrogen chloride recovery pipe, 17, liquid outlet pipe, 18, liquid delivery pump, 19, acid addition pipe, 20, spray pipe, 21, separation tank, 22, heat exchanger, 23, circulation pump, 24, hydrofluoric acid recovery pipe, 25, primary dispersion disk, 26, secondary dispersion packing section, 27, flow pipe, 28, mixed acid transfer tank, 29, sulfuric acid storage tank, 3 0. Mixed acid pipe, 31. Acid delivery pipe, 32. Mixed acid reflux pump, 33. Acid inlet pipe, 34. Acid inlet pump, 35. Acid outlet pipe, 36. Acid injection pump, 37. Vacuum unit, 38. Hydrofluoric acid recovery device, 39. Condenser, 40. Hydrofluoric acid receiving tank, 41. Hydrofluoric acid storage tank, 42. Hydrogen chloride falling film water absorption device, 43. Falling film absorption tower, 44. Liquid storage tank, 45. Reflux pipe, 46. Reflux pump, 47. Hydrochloric acid storage tank, 48. Residue discharge pipe, 49. Alkali washing absorption device, 50. Alkali washing absorption tower, 51. Waste liquid tank, 52. Reabsorption pipe, 53. Reabsorption pump, 54. Discharge pipe, 55. Reabsorption filler, 56. Spray pipe, 57. Sulfuric acid injection sleeve, 58. Mixed gas injection sleeve. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings: Example 1: A system for separating and purifying hydrogen chloride and hydrofluoric acid (see Figure 1 , Figure 2 ), comprising a sulfuric acid jet vacuum unit 1, a sulfuric acid absorption device 2 and a sulfuric acid separation device 3. The mixed gas of sulfuric acid, hydrogen chloride and hydrofluoric acid is mixed in the sulfuric acid jet vacuum unit 1 to absorb the hydrofluoric acid to form a mixed acid; the sulfuric acid jet vacuum unit 1 comprises a mixing tank 4 and a venturi jet pipe 5, an air inlet and a flow inlet are arranged at one end of the venturi jet pipe 5, and a jet port is arranged at the other end of the venturi jet pipe 5, the mixed gas of hydrogen chloride and hydrofluoric acid is introduced into the air inlet, the jet port is connected to the upper part of the mixing tank 4, an acid delivery pipe 6 is connected between the lower part of the mixing tank 4 and the flow inlet, and an acid delivery pump 7 is installed on the acid delivery pipe 6.

[0033] The mixed gas discharged from the sulfuric acid jet vacuum unit 1 enters the sulfuric acid absorption device 2 through the air delivery pipe 12 connected between the sulfuric acid jet vacuum unit 1 and the sulfuric acid absorption device 2, and is further mixed with sulfuric acid to absorb hydrofluoric acid to form a mixed acid. By utilizing the different saturated partial pressures and solubilities of HCL and HF in sulfuric acid, HCL is separated in the gas phase, and the separated hydrogen chloride is recycled.

[0034] By using the saturated vapor pressure principle of hydrofluoric acid and sulfuric acid at different temperatures, the mixed acid is separated to obtain sulfuric acid and hydrofluoric acid, the sulfuric acid is refluxed to the sulfuric acid jet vacuum unit 1 and the sulfuric acid absorption device 2 for repeated use, and the hydrofluoric acid is recovered.

[0035] The sulfuric acid absorption device 2 includes an upper spray cylinder 13 and a lower mixed acid liquid storage cylinder 14, and a sulfuric acid spray pipe 15 is installed in the spray cylinder 13. The sulfuric acid spray pipe 15 is arranged on the upper part of the spray cylinder 13, and the upper end of the spray cylinder 13 is connected to the hydrogen chloride recovery pipe 16. The air supply pipe 12 is connected between the lower part of the spray pipe and the upper part of the mixing tank 4 of the sulfuric acid injection vacuum unit 1. The mixed acid liquid storage cylinder 14 is connected to the liquid outlet pipe 17, and a liquid delivery pump 18 is installed on the liquid outlet pipe 17. The liquid outlet pipe 17 is connected to the acid addition pipe 19 and the liquid spray pipe 20. The acid addition pipe 19 and the liquid spray pipe 20 are connected in parallel to the liquid outlet pipe 17, and the acid addition pipe 19 is connected to the upper part of the mixing tank 4, and the liquid spray pipe 20 is connected to the spray pipe.

[0036] The sulfuric acid separation device 3 includes a separation tank 21 and a heat exchanger 22, wherein the inlet end of the heat exchanger 22 is connected to the bottom of the separation tank 21, and the outlet end of the heat exchanger 22 is connected to the top of the separation tank 21. A circulation pump 23 is installed on the pipeline between the inlet end of the heat exchanger 22 and the bottom of the separation tank 21, and the top of the separation tank 21 is connected to a hydrofluoric acid recovery pipe 24. A primary dispersion disc 25 and a secondary dispersion packing section 26 are installed in the separation tank 21, wherein the primary dispersion disc 25 is placed above the secondary dispersion packing section 26, and a plurality of flow pipes 27 are evenly arranged on the primary dispersion disc 25, wherein the upper end of the flow pipe 27 is higher than the primary dispersion disc 25, and the upper end openings of all the flow pipes 27 are flush.

[0037] The separation tank 21 is connected to the mixed acid transfer tank 28 and the sulfuric acid storage tank 29 through pipelines, the mixed acid transfer tank 28 is connected to the sulfuric acid injection vacuum unit 1 through the mixed acid pipe 30, and the sulfuric acid storage tank 29 is connected to the sulfuric acid absorption device 2 through the acid delivery pipe 31.

[0038] The mixed acid pipe 30 is connected to the bottom of the mixing tank 4 of the sulfuric acid jet vacuum unit 1, and a mixed acid reflux pump 32 is installed on the mixed acid pipe 30. The mixed acid reflux pump 32 extracts the mixed acid in the mixing tank 4 and transports it to the mixed acid transfer tank 28. An acid inlet pipe 33 is installed between the mixed acid transfer tank 28 and the upper part of the separation tank 21. An acid inlet pump 34 is installed on the acid inlet pipe 33. The acid inlet pump 34 extracts the mixed acid in the mixed acid transfer tank 28 and transports it to the separation tank 21. The sulfuric acid storage tank 29 is connected to the acid outlet pipe 35, and the acid outlet pipe 35 is connected to the pipeline between the heat exchanger 22 and the circulation pump 23. An acid delivery pipe 31 is installed between the bottom of the sulfuric acid storage tank 29 and the upper part of the mixed acid liquid storage cylinder 14, and an acid injection pump 36 is installed on the acid delivery pipe 31.

[0039] The separation tank 21 is connected to the vacuum unit 37 through a pipeline. The vacuum unit 37 evacuates the separation tank 21, thereby reducing the temperature required for gas-phase hydrofluoric acid separation to prevent the corrosion resistance of the separation tank 21 from being affected by excessive temperature. After the mixed acid is transported to the separation tank 21 through the acid inlet pump 34, the acid inlet pipe 33, the acid outlet pipe 35 and the hydrofluoric acid recovery pipe 24 are closed, and the vacuum unit 37 is started to evacuate the separation tank 21 to reduce the pressure in the separation tank 21. After reaching the set pressure, the vacuum unit 37 is closed. Then, the heat exchanger 22 and the circulation pump 23 are started to separate the mixed acid in the separation tank 21.

[0040] The sulfuric acid separation device 3 is connected to the hydrofluoric acid recovery device 38 through the hydrofluoric acid recovery pipe 24. The hydrofluoric acid recovery device 38 includes a condenser 39 and a hydrofluoric acid receiving tank 40. The condenser 39 is connected between the hydrofluoric acid recovery pipe 24 and the hydrofluoric acid receiving tank 40. The separated gaseous hydrofluoric acid is converted into a liquid phase after passing through the condenser 39 and flows into the hydrofluoric acid receiving tank 40 for collection. The bottom of the hydrofluoric acid receiving tank 40 is connected to the hydrofluoric acid storage tank 41 through a pipeline, and the liquid phase hydrofluoric acid is recovered to the hydrofluoric acid storage tank 41 for production.

[0041] The sulfuric acid absorption device 2 is connected to the hydrogen chloride falling film water absorption device 42 through the hydrogen chloride recovery pipe 16. The hydrogen chloride falling film water absorption device 42 includes a falling film absorption tower 43 and a liquid storage tank 44. The falling film absorption tower 43 is connected to the upper end of the liquid storage tank 44. The hydrogen chloride recovery pipe 16 is connected to the top of the falling film absorption tower 43. A reflux pipe 45 is installed between the top of the falling film absorption tower 43 and the bottom of the liquid storage tank 44. A reflux pump 46 is installed on the reflux pipe 45. The reflux pump 46 extracts the hydrochloric acid solution in the liquid storage tank 44 and transports it to the top of the falling film absorption tower 43 for absorbing gaseous hydrogen chloride. The liquid outlet side of the reflux pump 46 on the reflux pipe 45 is connected to the hydrochloric acid storage tank 47 through a pipeline, and the hydrochloric acid in the liquid storage tank 44 is transported to the hydrochloric acid storage tank 47 for production.

[0042] The top of the liquid storage tank 44 is connected to the alkali washing absorption device 49 through the residual discharge pipe 48. The alkali washing absorption device 49 includes an alkali washing absorption tower 50 and a waste liquid tank 51. A reabsorption pipe 52 is installed between the upper part of the alkali washing absorption tower 50 and the bottom of the waste liquid tank 51. A reabsorption pump 53 is installed on the reabsorption pipe 52. The residual discharge pipe 48 is connected to the bottom of the alkali washing absorption tower 50. A discharge pipe 54 is installed on the top of the alkali washing absorption tower 50. A reabsorption filler 55 and a spray pipe 56 are installed near the top of the alkali washing absorption tower 50. The spray pipe 56 is arranged below the reabsorption filler 55. The spray pipe 56 is connected to the reabsorption pipe 52. The spray pipe 56 sprays the reabsorption liquid downward.

[0043] A method for separating and purifying hydrogen chloride and hydrofluoric acid is operated by a hydrogen chloride and hydrofluoric acid separation and purification system, comprising the following steps: S1, a mixed gas of hydrogen chloride and hydrofluoric acid is transported to a sulfuric acid injection vacuum unit 1 to be mixed with sulfuric acid, and sulfuric acid in an acid delivery pipe 6 is transported to an inlet of a venturi injection pipe 5 to generate negative pressure at an air inlet position, thereby sucking the mixed gas into the venturi injection pipe 5 from the air inlet of the venturi injection pipe 5, mixing sulfuric acid and the mixed gas, and sulfuric acid absorbs hydrofluoric acid to form mixed acid that is transported to a sulfuric acid separation device 3.

[0044] S2, the mixed gas output by the sulfuric acid jet vacuum unit 1 enters the sulfuric acid absorption device 2 through the air delivery pipe 12, further mixes with sulfuric acid to absorb hydrofluoric acid to form a mixed acid, and is transported to the sulfuric acid separation device 3, and the separated hydrogen chloride is recovered; the hydrogen chloride gas separated by the sulfuric acid absorption device 2 is transported to the falling film absorption tower 43 of the hydrogen chloride falling film water absorption device 42 through the hydrogen chloride recovery pipe 16, and the reflux pump 46 extracts the hydrochloric acid solution in the liquid storage tank 44 and transports it to the top of the falling film absorption tower 43 for absorbing gaseous hydrogen chloride. The liquid outlet side of the reflux pump 46 on the reflux pipe 45 is connected to the hydrochloric acid storage tank 47 through a pipeline, and the hydrochloric acid in the liquid storage tank 44 is transported to the hydrochloric acid storage tank 47 for production. The residual discharge pipe 48 is connected to the bottom of the alkali washing absorption tower 50, and the spray pipe 56 sprays the heavy absorption liquid downward to absorb the residual meteorological hydrogen chloride.

[0045] S3, the mixed acid is decomposed in the sulfuric acid separation device 3 to obtain sulfuric acid and hydrofluoric acid, the sulfuric acid is refluxed to the sulfuric acid injection vacuum unit 1 and the sulfuric acid absorption device 2 for reuse, and the hydrofluoric acid is recovered. The gaseous hydrofluoric acid separated in the separation tank 21 is converted into a liquid phase after passing through the condenser 39, and flows to the hydrofluoric acid receiving tank 40 for collection. The bottom of the hydrofluoric acid receiving tank 40 is connected to the hydrofluoric acid storage tank 41 through a pipeline, and the liquid hydrofluoric acid is recovered to the hydrofluoric acid storage tank 41 for production.

[0046] In this patent, sulfuric acid is first used to absorb the hydrofluoric acid in the mixed gas of hydrogen chloride and hydrofluoric acid, thereby separating the hydrogen chloride, and then recovering the hydrogen chloride. The mixed acid formed after sulfuric acid absorbs the hydrofluoric acid is separated by the sulfuric acid separation device 3, and the hydrofluoric acid gas can be separated after the mixed acid is heated, and the hydrofluoric acid is recovered, and the remaining is sulfuric acid, which is reused. After the mixed gas of hydrogen chloride and hydrofluoric acid passes through the hydrogen chloride and hydrofluoric acid separation and purification system, hydrogen chloride and hydrofluoric acid can be separated, and sulfuric acid is recycled in the entire system, achieving the purpose of greatly reducing production costs.

[0047] Through the sulfuric acid jet vacuum unit 1, the front end system of the unit is in a negative pressure state, and the rear end of the unit is in a positive pressure state, so that the gas phase can be normally transported and flowed. At the same time, the venturi tube of the unit can achieve the effect of mixing and absorption. Under the condition of sulfuric acid spraying, the sulfuric acid absorption device 2 is mixed twice to achieve the purpose of completely separating HF and HCL. After sulfuric acid is mixed with the mixed gas, HF is absorbed to form mixed acid. After the mixed acid is heated in the sulfuric acid separation device 3, HF gas can be separated, and the remaining sulfuric acid is refluxed to the sulfuric acid jet vacuum unit 1 and the sulfuric acid absorption device 2 for reuse.

[0048] Example 2: A system for separating and purifying hydrogen chloride and hydrofluoric acid (see Figure 1 , Figure 2 , Figure 3 ), comprising a sulfuric acid jet vacuum unit 1, a sulfuric acid absorption device 2 and a sulfuric acid separation device 3. The mixed gas of sulfuric acid, hydrogen chloride and hydrofluoric acid is mixed in the sulfuric acid jet vacuum unit 1 to absorb the hydrofluoric acid to form a mixed acid; the sulfuric acid jet vacuum unit 1 comprises a mixing tank 4 and a venturi jet pipe 5, an air inlet and a flow inlet are arranged at one end of the venturi jet pipe 5, and a jet port is arranged at the other end of the venturi jet pipe 5, the mixed gas of hydrogen chloride and hydrofluoric acid is introduced into the air inlet, the jet port is connected to the upper part of the mixing tank 4, an acid delivery pipe 6 is connected between the lower part of the mixing tank 4 and the flow inlet, and an acid delivery pump 7 is installed on the acid delivery pipe 6.

[0049] The mixing tank 4 is connected to the secondary mixing mechanism 8, and the secondary mixing mechanism 8 includes an acid adding chamber 9 and a gas mixing chamber 10. The acid adding chamber 9 is connected to the sulfuric acid absorption device 2 through the acid adding pipe 19, and the gas mixing chamber 10 is connected to the injection port of the venturi injection pipe 5. The lower widths of the acid adding chamber 9 and the gas mixing chamber 10 are gradually reduced from top to bottom so that a water curtain notch 11 is formed at the lower opening end, and the center lines of the two water curtain notches 11 intersect below the water curtain notch 11. The acid adding chamber 9 and the gas mixing chamber 10 are arranged adjacent to each other. After sulfuric acid and the mixed gas are mixed in the venturi injection pipe 5, they are injected into the gas mixing chamber 10 from the injection port, and ejected from the water curtain notch 11 at the lower end of the gas mixing chamber 10 to form a gas-water mixing curtain. In the process of forming the gas-water mixing curtain, the mixing effect of the mixed gas and sulfuric acid can be improved, thereby improving the absorption effect of sulfuric acid on hydrofluoric acid. Sulfuric acid is transported from the acid adding pipe 19 to the acid adding chamber 9, and is sprayed out from the water curtain slot 11 at the lower end of the acid adding chamber 9 to form a water curtain. Since the center lines of the two water curtain slots 11 intersect below the water curtain slot 11, the gas-water mixed curtain and the water curtain sprayed from the two water curtain slots 11 will collide together, further achieving the mixing of sulfuric acid and the mixed gas, improving the mixing effect, and improving the absorption effect of sulfuric acid on hydrofluoric acid.

[0050] The mixed gas discharged from the sulfuric acid jet vacuum unit 1 enters the sulfuric acid absorption device 2 through the air delivery pipe 12 connected between the sulfuric acid jet vacuum unit 1 and the sulfuric acid absorption device 2, and is further mixed with sulfuric acid to absorb hydrofluoric acid to form a mixed acid. By utilizing the different saturated partial pressures and solubilities of HCL and HF in sulfuric acid, HCL is separated in the gas phase, and the separated hydrogen chloride is recycled.

[0051] By using the saturated vapor pressure principle of hydrofluoric acid and sulfuric acid at different temperatures, the mixed acid is separated to obtain sulfuric acid and hydrofluoric acid, the sulfuric acid is refluxed to the sulfuric acid jet vacuum unit 1 and the sulfuric acid absorption device 2 for repeated use, and the hydrofluoric acid is recovered.

[0052] The sulfuric acid absorption device 2 includes an upper spray cylinder 13 and a lower mixed acid liquid storage cylinder 14, and a sulfuric acid spray pipe 15 is installed in the spray cylinder 13. The sulfuric acid spray pipe 15 is arranged on the upper part of the spray cylinder 13, and the upper end of the spray cylinder 13 is connected to the hydrogen chloride recovery pipe 16. The air supply pipe 12 is connected between the lower part of the spray pipe and the upper part of the mixing tank 4 of the sulfuric acid injection vacuum unit 1. The mixed acid liquid storage cylinder 14 is connected to the liquid outlet pipe 17, and a liquid delivery pump 18 is installed on the liquid outlet pipe 17. The liquid outlet pipe 17 is connected to the acid addition pipe 19 and the liquid spray pipe 20. The acid addition pipe 19 and the liquid spray pipe 20 are connected in parallel to the liquid outlet pipe 17, and the acid addition pipe 19 is connected to the upper part of the mixing tank 4, and the liquid spray pipe 20 is connected to the spray pipe.

[0053] The sulfuric acid separation device 3 includes a separation tank 21 and a heat exchanger 22, wherein the inlet end of the heat exchanger 22 is connected to the bottom of the separation tank 21, and the outlet end of the heat exchanger 22 is connected to the top of the separation tank 21. A circulation pump 23 is installed on the pipeline between the inlet end of the heat exchanger 22 and the bottom of the separation tank 21, and the top of the separation tank 21 is connected to a hydrofluoric acid recovery pipe 24. A primary dispersion disc 25 and a secondary dispersion packing section 26 are installed in the separation tank 21, wherein the primary dispersion disc 25 is placed above the secondary dispersion packing section 26, and a plurality of flow pipes 27 are evenly arranged on the primary dispersion disc 25, wherein the upper end of the flow pipe 27 is higher than the primary dispersion disc 25, and the upper end openings of all the flow pipes 27 are flush.

[0054] The separation tank 21 is connected to the mixed acid transfer tank 28 and the sulfuric acid storage tank 29 through pipelines, the mixed acid transfer tank 28 is connected to the sulfuric acid injection vacuum unit 1 through the mixed acid pipe 30, and the sulfuric acid storage tank 29 is connected to the sulfuric acid absorption device 2 through the acid delivery pipe 31.

[0055] The mixed acid pipe 30 is connected to the bottom of the mixing tank 4 of the sulfuric acid jet vacuum unit 1, and a mixed acid reflux pump 32 is installed on the mixed acid pipe 30. The mixed acid reflux pump 32 extracts the mixed acid in the mixing tank 4 and transports it to the mixed acid transfer tank 28. An acid inlet pipe 33 is installed between the mixed acid transfer tank 28 and the upper part of the separation tank 21. An acid inlet pump 34 is installed on the acid inlet pipe 33. The acid inlet pump 34 extracts the mixed acid in the mixed acid transfer tank 28 and transports it to the separation tank 21. The sulfuric acid storage tank 29 is connected to the acid outlet pipe 35, and the acid outlet pipe 35 is connected to the pipeline between the heat exchanger 22 and the circulation pump 23. An acid delivery pipe 31 is installed between the bottom of the sulfuric acid storage tank 29 and the upper part of the mixed acid liquid storage cylinder 14, and an acid injection pump 36 is installed on the acid delivery pipe 31.

[0056] The separation tank 21 is connected to the vacuum unit 37 through a pipeline. The vacuum unit 37 evacuates the separation tank 21, thereby reducing the temperature required for gas-phase hydrofluoric acid separation to prevent the corrosion resistance of the separation tank 21 from being affected by excessive temperature. After the mixed acid is transported to the separation tank 21 through the acid inlet pump 34, the acid inlet pipe 33, the acid outlet pipe 35 and the hydrofluoric acid recovery pipe 24 are closed, and the vacuum unit 37 is started to evacuate the separation tank 21 to reduce the pressure in the separation tank 21. After reaching the set pressure, the vacuum unit 37 is closed. Then, the heat exchanger 22 and the circulation pump 23 are started to separate the mixed acid in the separation tank 21.

[0057] The sulfuric acid separation device 3 is connected to the hydrofluoric acid recovery device 38 through the hydrofluoric acid recovery pipe 24. The hydrofluoric acid recovery device 38 includes a condenser 39 and a hydrofluoric acid receiving tank 40. The condenser 39 is connected between the hydrofluoric acid recovery pipe 24 and the hydrofluoric acid receiving tank 40. The separated gaseous hydrofluoric acid is converted into a liquid phase after passing through the condenser 39 and flows into the hydrofluoric acid receiving tank 40 for collection. The bottom of the hydrofluoric acid receiving tank 40 is connected to the hydrofluoric acid storage tank 41 through a pipeline, and the liquid phase hydrofluoric acid is recovered to the hydrofluoric acid storage tank 41 for production.

[0058] The sulfuric acid absorption device 2 is connected to the hydrogen chloride falling film water absorption device 42 through the hydrogen chloride recovery pipe 16. The hydrogen chloride falling film water absorption device 42 includes a falling film absorption tower 43 and a liquid storage tank 44. The falling film absorption tower 43 is connected to the upper end of the liquid storage tank 44. The hydrogen chloride recovery pipe 16 is connected to the top of the falling film absorption tower 43. A reflux pipe 45 is installed between the top of the falling film absorption tower 43 and the bottom of the liquid storage tank 44. A reflux pump 46 is installed on the reflux pipe 45. The reflux pump 46 extracts the hydrochloric acid solution in the liquid storage tank 44 and transports it to the top of the falling film absorption tower 43 for absorbing gaseous hydrogen chloride. The liquid outlet side of the reflux pump 46 on the reflux pipe 45 is connected to the hydrochloric acid storage tank 47 through a pipeline, and the hydrochloric acid in the liquid storage tank 44 is transported to the hydrochloric acid storage tank 47 for production.

[0059] The top of the liquid storage tank 44 is connected to the alkali washing absorption device 49 through the residual discharge pipe 48. The alkali washing absorption device 49 includes an alkali washing absorption tower 50 and a waste liquid tank 51. A reabsorption pipe 52 is installed between the upper part of the alkali washing absorption tower 50 and the bottom of the waste liquid tank 51. A reabsorption pump 53 is installed on the reabsorption pipe 52. The residual discharge pipe 48 is connected to the bottom of the alkali washing absorption tower 50. A discharge pipe 54 is installed on the top of the alkali washing absorption tower 50. A reabsorption filler 55 and a spray pipe 56 are installed near the top of the alkali washing absorption tower 50. The spray pipe 56 is arranged below the reabsorption filler 55. The spray pipe 56 is connected to the reabsorption pipe 52. The spray pipe 56 sprays the reabsorption liquid downward.

[0060] A method for separating and purifying hydrogen chloride and hydrofluoric acid is operated by a hydrogen chloride and hydrofluoric acid separation and purification system, comprising the following steps: S1, a mixed gas of hydrogen chloride and hydrofluoric acid is transported to a sulfuric acid injection vacuum unit 1 to be mixed with sulfuric acid, and sulfuric acid in an acid delivery pipe 6 is transported to an inlet of a venturi injection pipe 5 to generate negative pressure at an air inlet position, thereby sucking the mixed gas into the venturi injection pipe 5 from the air inlet of the venturi injection pipe 5, mixing sulfuric acid and the mixed gas, and sulfuric acid absorbs hydrofluoric acid to form mixed acid that is transported to a sulfuric acid separation device 3.

[0061] S2, the mixed gas output by the sulfuric acid jet vacuum unit 1 enters the sulfuric acid absorption device 2 through the air delivery pipe 12, further mixes with sulfuric acid to absorb hydrofluoric acid to form a mixed acid, and is transported to the sulfuric acid separation device 3, and the separated hydrogen chloride is recovered; the hydrogen chloride gas separated by the sulfuric acid absorption device 2 is transported to the falling film absorption tower 43 of the hydrogen chloride falling film water absorption device 42 through the hydrogen chloride recovery pipe 16, and the reflux pump 46 extracts the hydrochloric acid solution in the liquid storage tank 44 and transports it to the top of the falling film absorption tower 43 for absorbing gaseous hydrogen chloride. The liquid outlet side of the reflux pump 46 on the reflux pipe 45 is connected to the hydrochloric acid storage tank 47 through a pipeline, and the hydrochloric acid in the liquid storage tank 44 is transported to the hydrochloric acid storage tank 47 for production. The residual discharge pipe 48 is connected to the bottom of the alkali washing absorption tower 50, and the spray pipe 56 sprays the heavy absorption liquid downward to absorb the residual meteorological hydrogen chloride.

[0062] S3, the mixed acid is decomposed in the sulfuric acid separation device 3 to obtain sulfuric acid and hydrofluoric acid, the sulfuric acid is refluxed to the sulfuric acid injection vacuum unit 1 and the sulfuric acid absorption device 2 for reuse, and the hydrofluoric acid is recovered. The gaseous hydrofluoric acid separated in the separation tank 21 is converted into a liquid phase after passing through the condenser 39, and flows to the hydrofluoric acid receiving tank 40 for collection. The bottom of the hydrofluoric acid receiving tank 40 is connected to the hydrofluoric acid storage tank 41 through a pipeline, and the liquid hydrofluoric acid is recovered to the hydrofluoric acid storage tank 41 for production.

[0063] In this patent, sulfuric acid is first used to absorb the hydrofluoric acid in the mixed gas of hydrogen chloride and hydrofluoric acid, thereby separating the hydrogen chloride, and then recovering the hydrogen chloride. The mixed acid formed after sulfuric acid absorbs the hydrofluoric acid is separated by the sulfuric acid separation device 3, and the hydrofluoric acid gas can be separated after the mixed acid is heated, and the hydrofluoric acid is recovered, and the remaining is sulfuric acid, which is reused. After the mixed gas of hydrogen chloride and hydrofluoric acid passes through the hydrogen chloride and hydrofluoric acid separation and purification system, hydrogen chloride and hydrofluoric acid can be separated, and sulfuric acid is recycled in the entire system, achieving the purpose of greatly reducing production costs.

[0064] Through the sulfuric acid jet vacuum unit 1, the front end system of the unit is in a negative pressure state, and the rear end of the unit is in a positive pressure state, so that the gas phase can be normally transported and flowed. At the same time, the venturi tube of the unit can achieve the effect of mixing and absorption. Under the condition of sulfuric acid spraying, the sulfuric acid absorption device 2 is mixed twice to achieve the purpose of completely separating HF and HCL. After sulfuric acid is mixed with the mixed gas, HF is absorbed to form mixed acid. After the mixed acid is heated in the sulfuric acid separation device 3, HF gas can be separated, and the remaining sulfuric acid is refluxed to the sulfuric acid jet vacuum unit 1 and the sulfuric acid absorption device 2 for reuse.

[0065] Example 3: A system for separating and purifying hydrogen chloride and hydrofluoric acid (see Figure 1 , Figure 2 , Figure 4 ), its structural principle is similar to that of Example 2, the main difference is that in this embodiment, the secondary mixing mechanism 8 includes an acid adding chamber 9 and a gas mixing chamber 10, the acid adding chamber 9 is connected to the sulfuric acid absorption device 2 through the acid adding pipe 19, the gas mixing chamber 10 is connected to the injection port of the venturi injection pipe 5, a plurality of sulfuric acid injection sleeves 57 are arranged at the bottom of the acid adding chamber 9, and a plurality of gas mixing injection sleeves 58 are arranged at the bottom of the gas mixing chamber 10, the gas mixing injection sleeves 58 and the sulfuric acid injection sleeves 57 are arranged one by one, the lower end of the gas mixing injection sleeve 58 is placed in the sulfuric acid injection sleeve 57, the apertures of the gas mixing injection sleeve 58 and the sulfuric acid injection sleeve 57 are gradually reduced from top to bottom, and a gap is arranged between the outer wall of the gas mixing injection sleeve 58 and the inner wall of the sulfuric acid injection sleeve 57. The gas mixing chamber 10 is arranged in the acid adding chamber 9.

[0066] After sulfuric acid and the mixed gas are mixed in the venturi injection tube 5, they are injected into the gas mixing chamber 10 from the injection port and ejected from the gas mixing injection sleeve 58 at the lower end of the gas mixing chamber 10. Sulfuric acid is transported to the acid adding chamber 9 from the acid adding pipe 19 and ejected from the sulfuric acid injection sleeve 57 at the lower end of the acid adding chamber 9. The drainage effect of the sulfuric acid injection sleeve 57 can accelerate the ejection of the mixed liquid in the gas mixing injection sleeve 58, and the mixed liquid and sulfuric acid are further mixed in the sulfuric acid injection sleeve 57, thereby improving the mixing effect and the absorption effect of sulfuric acid on hydrofluoric acid. The other structures are the same as those in Example 2.

[0067] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A system for separating and purifying hydrogen chloride and hydrofluoric acid, characterized in that: include: Sulfuric acid jet vacuum unit, in which the mixed gas of sulfuric acid, hydrogen chloride and hydrofluoric acid is mixed and absorbs hydrofluoric acid to form mixed acid; Sulfuric acid absorption device, the mixed gas discharged from the sulfuric acid injection vacuum unit enters the sulfuric acid absorption device and further mixes with sulfuric acid to absorb hydrofluoric acid to form mixed acid, and hydrogen chloride is separated and recovered; The sulfuric acid separation device separates the mixed acid into sulfuric acid and hydrofluoric acid. The sulfuric acid is refluxed to the sulfuric acid injection vacuum unit and the sulfuric acid absorption device for repeated use, and the hydrofluoric acid is recovered.

2. A system for separating and purifying hydrogen chloride and hydrofluoric acid according to claim 1, characterized in that: The sulfuric acid absorption device comprises an upper spray cylinder and a lower mixed acid storage cylinder, and a sulfuric acid spray pipe is installed in the spray cylinder.

3. A system for separating and purifying hydrogen chloride and hydrofluoric acid according to claim 1, characterized in that: The sulfuric acid separation device comprises a separation tank and a heat exchanger, wherein the inlet end of the heat exchanger is connected to the bottom of the separation tank, and the outlet end of the heat exchanger is connected to the top of the separation tank.

4. A system for separating and purifying hydrogen chloride and hydrofluoric acid according to claim 3, characterized in that: A primary dispersion plate and a secondary dispersion filler section are installed in the separation tank. A plurality of flow pipes are evenly arranged on the primary dispersion plate, and the upper ends of the flow pipes are higher than the primary dispersion plate.

5. A system for separating and purifying hydrogen chloride and hydrofluoric acid according to claim 3, characterized in that: The separation tank is connected to the vacuum unit through a pipeline.

6. A system for separating and purifying hydrogen chloride and hydrofluoric acid according to claim 3, characterized in that: The separation tank is connected to the mixed acid transfer tank and the sulfuric acid storage tank through pipelines, the mixed acid transfer tank is connected to the sulfuric acid injection vacuum unit through the mixed acid pipe, and the sulfuric acid storage tank is connected to the sulfuric acid absorption device through the acid pipe.

7. A system for separating and purifying hydrogen chloride and hydrofluoric acid according to claim 1, characterized in that: The sulfuric acid separation device is connected to the hydrofluoric acid recovery device through a hydrofluoric acid recovery pipe. The hydrofluoric acid recovery device includes a condenser and a hydrofluoric acid receiving tank. The condenser is connected between the hydrofluoric acid recovery pipe and the hydrofluoric acid receiving tank.

8. A system for separating and purifying hydrogen chloride and hydrofluoric acid according to any one of claims 1 to 7, characterized in that: The sulfuric acid absorption device is connected to the hydrogen chloride falling film water absorption device through a hydrogen chloride recovery pipe.

9. A system for separating and purifying hydrogen chloride and hydrofluoric acid according to any one of claims 1 to 7, characterized in that: The sulfuric acid jet vacuum unit includes a mixing tank and a venturi jet pipe. The mixing tank is connected to a secondary mixing mechanism. The secondary mixing mechanism includes an acid adding chamber and a gas mixing chamber. The acid adding chamber is connected to the sulfuric acid absorption device through the acid adding pipe. The gas mixing chamber is connected to the jet port of the venturi jet pipe. The lower widths of the acid adding chamber and the gas mixing chamber are gradually reduced from top to bottom to form a water curtain slot at the lower opening end. The center lines of the two water curtain slots intersect below the water curtain slot.

10. A method for separating and purifying hydrogen chloride and hydrofluoric acid, characterized in that: The operation of the hydrogen chloride and hydrofluoric acid separation and purification system according to any one of claims 1 to 9 comprises the following steps: S1, a mixed gas of hydrogen chloride and hydrofluoric acid is transported to a sulfuric acid jet vacuum unit to be mixed with sulfuric acid, the sulfuric acid absorbs the hydrofluoric acid to form a mixed acid, which is transported to a sulfuric acid separation device; S2, the mixed gas output by the sulfuric acid jet vacuum unit enters a sulfuric acid absorption device to be further mixed with sulfuric acid to absorb hydrofluoric acid to form a mixed acid, which is transported to a sulfuric acid separation device, and the separated hydrogen chloride is recovered; S3, the mixed acid is decomposed in the sulfuric acid separation device to obtain sulfuric acid and hydrofluoric acid, the sulfuric acid is refluxed to the sulfuric acid jet vacuum unit and the sulfuric acid absorption device for repeated use, and the hydrofluoric acid is recovered.

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