A system and method for separating and purifying hydrogen chloride and hydrofluoric acid

Abstract

The present invention discloses a system and method for separating and purifying hydrogen chloride and hydrofluoric acid, belonging to the technical field of mixed gas separation. The system aims to solve the problem that the treatment of the mixed gas of hydrogen chloride and hydrofluoric acid not only consumes a large amount of alkali solution but also affects the environment. The invention includes a sulfuric acid jet vacuum unit, a sulfuric acid absorption device, and a sulfuric acid separation device. The mixed gas of sulfuric acid, hydrogen chloride, and hydrofluoric acid is mixed in the sulfuric acid jet vacuum unit to absorb hydrofluoric acid to form a mixed acid; the mixed gas discharged from the sulfuric acid jet vacuum unit enters the sulfuric acid absorption device and further mixes with sulfuric acid to absorb hydrofluoric acid to form a mixed acid, and hydrogen chloride is separated and recovered; the sulfuric acid separation device separates the mixed acid to obtain sulfuric acid and hydrofluoric acid, and the sulfuric acid is refluxed to the sulfuric acid jet vacuum unit and the sulfuric acid absorption device for reuse, and the hydrofluoric acid is recovered. The mixed gas of hydrogen chloride and hydrofluoric acid is separated to obtain hydrochloric acid and hydrofluoric acid, and the recycling reduces production costs, and the separation process does not generate hazardous waste.

Description

Technical Field

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

[0002] Lithium hexafluorophosphate (LiPF6) is currently used extensively as a primary raw material for battery electrolysis, and a growing number of companies are producing it. However, the mixed gases HCl and HF generated during the production process are absorbed into a mixed acid, a difficult-to-dispose waste material that significantly impacts manufacturers' costs and profits. Disposal of this mixed acid consumes significant amounts of alkali and other resources, and poses significant environmental and worker health risks. This presents a challenge faced by many leading LiPF6 manufacturers and a pressing issue they need to address. Summary of the Invention

[0003] 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 a mixed gas of hydrogen chloride and hydrofluoric acid into hydrochloric acid and hydrofluoric acid. The hydrochloric acid and hydrofluoric acid are recycled to reduce production costs. In addition, the separation process does not generate harmful waste, avoiding pollution to the environment.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solution: a hydrogen chloride and hydrofluoric acid separation and purification system, comprising:

[0005] Sulfuric acid jet vacuum unit: a mixture of sulfuric acid, hydrogen chloride and hydrofluoric acid is mixed in the sulfuric acid jet vacuum unit to absorb hydrofluoric acid to form mixed acid;

[0006] Sulfuric acid absorption device: the mixed gas discharged from the sulfuric acid jet 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;

[0007] 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 reuse, and the hydrofluoric acid is recovered.

[0008] In this patent, sulfuric acid is first used to absorb the hydrofluoric acid in the hydrogen chloride and hydrofluoric acid mixture, thereby separating the hydrogen chloride, which is then recovered. The mixed acid formed after the sulfuric acid absorbs the hydrofluoric acid is separated by a sulfuric acid separation device. After the mixed acid is heated, the hydrofluoric acid gas is separated and recovered, leaving the remaining sulfuric acid, which is reused. After the hydrogen chloride and hydrofluoric acid mixture passes through the hydrogen chloride and hydrofluoric acid separation and purification system, the hydrogen chloride and hydrofluoric acid are separated. The sulfuric acid is recycled throughout the entire system, significantly reducing production costs.

[0009] The sulfuric acid jet vacuum unit maintains a negative pressure system at the front end and a positive pressure system at the rear end, ensuring proper gas transport and flow. The unit's Venturi tube also provides mixing and absorption. Within the sulfuric acid absorption unit, secondary mixing occurs under the sulfuric acid spray, achieving complete separation of HF and HCl. The sulfuric acid mixes with the mixed gas, absorbing HF to form mixed acid. After heating in the sulfuric acid separation unit, the mixed acid separates the HF gas, while the remaining sulfuric acid flows back to the sulfuric acid jet vacuum unit and the sulfuric acid absorption unit for reuse.

[0010] The hydrogen chloride and hydrofluoric acid separation and purification system disclosed in this 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. In addition, the separation process does not generate harmful waste, avoiding pollution to the environment.

[0011] Preferably, the sulfuric acid absorption device comprises an upper spray cylinder and a lower mixed acid liquid storage cylinder, and a sulfuric acid spray pipe is installed in the spray cylinder.

[0012] The sulfuric acid spray pipe sprays sulfuric acid into the spray cylinder. 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.

[0013] Preferably, the sulfuric acid separation device includes 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.

[0014] The heat exchanger heats the mixed acid in the separation tank to separate the hydrofluoric acid in the gas phase.

[0015] Preferably, a primary dispersion disk and a secondary dispersion filler section are installed in the separation tank, and a plurality of flow pipes are evenly distributed on the primary dispersion disk, with the upper ends of the flow pipes being higher than the primary dispersion disk.

[0016] After the mixed acid is delivered to the separation tank, it first falls onto the primary dispersion plate. When the liquid level exceeds the upper opening of the draft tube, it flows down the draft tube. This process disperses the mixed acid and facilitates the separation of gaseous hydrofluoric acid. The secondary dispersion packing section further disperses the mixed acid, further improving the separation of gaseous hydrofluoric acid.

[0017] Preferably, the separation tank is connected to the vacuum unit via a pipeline.

[0018] 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.

[0019] 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 pipe.

[0020] The mixed acid transfer tank is used to store mixed acid, and the sulfuric acid storage tank is used to store separated sulfuric acid.

[0021] 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.

[0022] 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.

[0023] Preferably, the sulfuric acid absorption device is connected to the hydrogen chloride falling film water absorption device through a hydrogen chloride recovery pipe.

[0024] The separated gaseous hydrogen chloride passes through the hydrogen chloride falling film water absorption device, contacts and mixes with water to form a hydrochloric acid solution, which is easy to collect and utilize.

[0025] Preferably, 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 injection port of the venturi jet pipe, the lower widths of the acid adding chamber and the gas mixing chamber gradually decrease from top to bottom so that the lower open end forms a water curtain notch, and the center lines of the two water curtain notches intersect below the water curtain notch.

[0026] After mixing in the Venturi injection tube, sulfuric acid and the mixed gas are injected into the mixing chamber from the injection port and ejected from the water curtain slot at the lower end of the mixing chamber to form a gas-water mixing curtain. This process improves the mixing effect of the mixed gas and sulfuric acid, thereby enhancing the absorption of hydrofluoric acid by sulfuric acid. Sulfuric acid is transported into the acid addition chamber from the acid addition pipe and ejected from the water curtain slot at the lower end of the acid addition chamber to form a water curtain. Because the centerlines of the two water curtain slots intersect below the water curtain slot, the gas-water mixing curtain ejected from the two water curtain slots and the water curtain collide with each other, further mixing the sulfuric acid and the mixed gas, improving the mixing effect and enhancing the absorption of hydrofluoric acid by sulfuric acid.

[0027] 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 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 reuse, and the hydrofluoric acid is recovered.

[0028] Sulfuric acid is mixed with a mixture of hydrogen chloride and hydrofluoric acid. The sulfuric acid absorbs the hydrofluoric acid to form a mixed acid, which then separates the gaseous hydrogen chloride. The mixed acid of sulfuric acid and hydrofluoric acid can be separated into gaseous hydrogen fluoride simply by heating. The separated sulfuric acid is returned to the system as a medium and is not consumed. The separated hydrogen chloride and hydrogen fluoride can be recycled, reducing production costs. Furthermore, the separation process does not generate hazardous waste, thus preventing environmental pollution.

[0029] Compared with the prior art, the beneficial effects of the present invention are: (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 pollution to the environment; (2) the separated sulfuric acid is returned to the system and used as a medium without being consumed. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of the present invention.

[0031] Figure 2 It is a structural schematic diagram of the separation tank of the present invention.

[0032] Figure 3 It is a structural diagram of the secondary mixing mechanism of Example 2 of the present invention.

[0033] Figure 4 It is a structural diagram of the secondary mixing mechanism of Example 3 of the present invention.

[0034] In the figure: 1. Sulfuric acid jet vacuum unit, 2. Sulfuric acid absorption device, 3. Sulfuric acid separation device, 4. Mixing tank, 5. Venturi injection pipe, 6. Acid feeding pipe, 7. Acid feeding pump, 8. Secondary mixing mechanism, 9. Acid adding chamber, 10. Gas mixing chamber, 11. Water curtain notch, 12. Gas feeding pipe, 13. Spraying tube, 14. Mixed acid storage cylinder, 15. Sulfuric acid spraying pipe, 16. Hydrogen chloride recovery pipe, 17. Liquid outlet pipe, 18. Liquid feeding pump, 19. Acid adding pipe, 20. Liquid spraying pipe, 21. Separation tank, 22. Heat exchanger, 23. Circulation pump, 24. Hydrofluoric acid recovery pipe, 25. Primary dispersion plate, 26. Secondary dispersion packing section, 27. Throughflow 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. Nozzle, 57. Sulfuric acid injection sleeve, 58. Mixed gas injection sleeve. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0036] 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. A mixture of sulfuric acid, hydrogen chloride, and hydrofluoric acid mixes within the sulfuric acid jet vacuum unit 1, absorbing 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. The venturi jet pipe 5 has an air inlet and a flow inlet at one end, and a jet port at the other end. The mixture of hydrogen chloride and hydrofluoric acid is introduced into the air inlet. The jet port is connected to the upper portion of the mixing tank 4. An acid delivery pipe 6 is connected between the lower portion of the mixing tank 4 and the flow inlet, and an acid delivery pump 7 is mounted on the acid delivery pipe 6.

[0037] The mixed gas discharged from the sulfuric acid jet vacuum unit 1 enters the sulfuric acid absorption device 2 through the air supply 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. 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.

[0038] The mixed acid is separated into sulfuric acid and hydrofluoric acid by using the saturated vapor pressure principle of hydrofluoric acid and sulfuric acid at different temperatures. The sulfuric acid is refluxed to the sulfuric acid jet vacuum unit 1 and the sulfuric acid absorption device 2 for reuse, and the hydrofluoric acid is recovered.

[0039] The sulfuric acid absorption unit 2 includes an upper spray cylinder 13 and a lower mixed acid liquid storage cylinder 14. A sulfuric acid spray pipe 15 is installed in the spray cylinder 13. The sulfuric acid spray pipe 15 is located above the spray cylinder 13, and the upper end of the spray cylinder 13 is connected to a hydrogen chloride recovery pipe 16. An air supply pipe 12 is connected between the lower portion of the spray pipe and the upper portion of the mixing tank 4 of the sulfuric acid injection vacuum unit 1. The mixed acid liquid storage cylinder 14 is connected to a liquid outlet pipe 17, on which a liquid feed pump 18 is installed. The liquid outlet pipe 17 is connected to an acid addition pipe 19 and a 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. The acid addition pipe 19 is connected to the upper portion of the mixing tank 4, and the liquid spray pipe 20 is connected to the spray pipe.

[0040] The sulfuric acid separation device 3 includes a separator 21 and a heat exchanger 22. The inlet of the heat exchanger 22 is connected to the bottom of the separator 21, and the outlet of the heat exchanger 22 is connected to the top of the separator 21. A circulation pump 23 is installed in the pipeline between the inlet of the heat exchanger 22 and the bottom of the separator 21. The top of the separator 21 is connected to a hydrofluoric acid recovery pipe 24. A primary dispersion plate 25 and a secondary dispersion packing section 26 are installed in the separator 21. The primary dispersion plate 25 is placed above the secondary dispersion packing section 26. A plurality of flow pipes 27 are evenly distributed on the primary dispersion plate 25. The upper ends of the flow pipes 27 are higher than the primary dispersion plate 25, and the upper ends of all the flow pipes 27 are flush.

[0041] 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. The sulfuric acid storage tank 29 is connected to the sulfuric acid absorption device 2 through the acid pipe 31.

[0042] A mixed acid pipe 30 is connected to the bottom of the mixing tank 4 of the sulfuric acid jet vacuum unit 1. A mixed acid reflux pump 32 is installed on the mixed acid pipe 30. The mixed acid reflux pump 32 extracts the mixed acid from 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 top of the separator tank 21. An acid inlet pump 34 is installed on the acid inlet pipe 33. The acid inlet pump 34 extracts the mixed acid from the mixed acid transfer tank 28 and transports it to the separator tank 21. The sulfuric acid storage tank 29 is connected to an acid outlet pipe 35, which 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 top of the mixed acid storage cylinder 14. An acid injection pump 36 is installed on the acid delivery pipe 31.

[0043] Separator 21 is connected to a vacuum unit 37 via a pipeline. This unit 37 evacuates separator 21, thereby lowering the temperature required for gaseous hydrofluoric acid separation and preventing excessive temperatures from affecting the corrosion resistance of separator 21. After the mixed acid is delivered to separator 21 via the acid inlet pump 34, the acid inlet pipe 33, the acid outlet pipe 35, and the hydrofluoric acid recovery pipe 24 are closed. The vacuum unit 37 is then activated to evacuate separator 21, reducing the pressure within separator 21. Once the pressure reaches the set point, the vacuum unit 37 is closed. The heat exchanger 22 and circulation pump 23 are then activated to separate the mixed acid within separator 21.

[0044] The sulfuric acid separation device 3 is connected to the hydrofluoric acid recovery device 38 via 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 a hydrofluoric acid storage tank 41 via a pipeline, and the liquid hydrofluoric acid is recovered in the hydrofluoric acid storage tank 41 for production.

[0045] Sulfuric acid absorption unit 2 is connected to hydrogen chloride falling film water absorption unit 42 via hydrogen chloride recovery pipe 16. Hydrogen chloride falling film water absorption unit 42 comprises a falling film absorption tower 43 and a liquid storage tank 44. Falling film absorption tower 43 is connected to the upper end of liquid storage tank 44, and hydrogen chloride recovery pipe 16 is connected to the top of falling film absorption tower 43. A reflux pipe 45 is installed between the top of falling film absorption tower 43 and the bottom of liquid storage tank 44. A reflux pump 46 is installed on reflux pipe 45. Reflux pump 46 extracts hydrochloric acid solution from liquid storage tank 44 and transports it to the top of falling film absorption tower 43 for absorption of gaseous hydrogen chloride. The liquid outlet of reflux pump 46 on reflux pipe 45 is connected to hydrochloric acid storage tank 47 via a pipeline. The hydrochloric acid in liquid storage tank 44 is transported to hydrochloric acid storage tank 47 for production.

[0046] 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 at the top of the alkali washing absorption tower 50. A reabsorption filler 55 and a nozzle 56 are installed near the top of the alkali washing absorption tower 50. The nozzle 56 is arranged below the reabsorption filler 55. The nozzle 56 is connected to the reabsorption pipe 52. The nozzle 56 sprays the reabsorption liquid downward.

[0047] A method for separating and purifying hydrogen chloride and hydrofluoric acid is operated using 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, the sulfuric acid in an acid feeding pipe 6 is transported to the inlet of a venturi injection pipe 5, a negative pressure is generated at the air inlet position, and the mixed gas is sucked into the venturi injection pipe 5 from the air inlet of the venturi injection pipe 5, so that the sulfuric acid and the mixed gas are mixed, and the sulfuric acid absorbs the hydrofluoric acid to form a mixed acid that is transported to a sulfuric acid separation device 3.

[0048] In step S2, the mixed gas output from the sulfuric acid jet vacuum unit 1 enters the sulfuric acid absorption unit 2 through the gas supply pipe 12, where it further mixes with sulfuric acid to absorb hydrofluoric acid, forming a mixed acid that is transported to the sulfuric acid separation unit 3, where the separated hydrogen chloride is recovered. The hydrogen chloride gas separated by the sulfuric acid absorption unit 2 is transported via the hydrogen chloride recovery pipe 16 to the falling film absorption tower 43 of the hydrogen chloride falling film water absorption unit 42. A reflux pump 46 draws hydrochloric acid solution from the liquid storage tank 44 and transports it to the top of the falling film absorption tower 43 for absorption of gaseous hydrogen chloride. The liquid outlet of the reflux pump 46 on the reflux pipe 45 is connected to the hydrochloric acid storage tank 47 via 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 gas discharge pipe 48 connects to the bottom of the alkaline wash absorption tower 50, where a spray pipe 56 sprays the reabsorbed liquid downward to absorb the residual gaseous hydrogen chloride.

[0049] In step S3, the mixed acid is decomposed in the sulfuric acid separation unit 3 to produce sulfuric acid and hydrofluoric acid. The sulfuric acid is refluxed to the sulfuric acid jet vacuum unit 1 and the sulfuric acid absorption unit 2 for reuse, while 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 then collected in the hydrofluoric acid receiving tank 40. The bottom of the hydrofluoric acid receiving tank 40 is connected to the hydrofluoric acid storage tank 41 via a pipeline, and the liquid hydrofluoric acid is recovered to the hydrofluoric acid storage tank 41 for use in production.

[0050] In this patent, sulfuric acid is first used to absorb the hydrofluoric acid in the hydrogen chloride and hydrofluoric acid mixed gas, thereby separating the hydrogen chloride, and then recovering the hydrogen chloride. The mixed acid formed after the sulfuric acid absorbs the hydrofluoric acid is separated by a sulfuric acid separation device 3. After the mixed acid is heated, the hydrofluoric acid gas can be separated and the hydrofluoric acid is recovered. The remaining sulfuric acid is reused. After the hydrogen chloride and hydrofluoric acid mixed gas passes through the hydrogen chloride and hydrofluoric acid separation and purification system, the hydrogen chloride and hydrofluoric acid can be separated. The sulfuric acid is recycled throughout the entire system, achieving the purpose of significantly reducing production costs.

[0051] The sulfuric acid jet vacuum unit 1 maintains a negative pressure at the front end of the unit and a positive pressure at the rear end, ensuring proper gas transport and flow. The unit's Venturi tube also provides mixing and absorption. Within the sulfuric acid absorption unit 2, secondary mixing occurs under the sulfuric acid spray, achieving complete separation of HF and HCl. The sulfuric acid mixes with the mixed gas, absorbing the HF to form a mixed acid. After heating in the sulfuric acid separation unit 3, the mixed acid separates the HF gas. The remaining sulfuric acid is then recycled back to the sulfuric acid jet vacuum unit 1 and sulfuric acid absorption unit 2 for reuse.

[0052] 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. A mixture of sulfuric acid, hydrogen chloride, and hydrofluoric acid mixes within the sulfuric acid jet vacuum unit 1, absorbing 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. The venturi jet pipe 5 has an air inlet and a flow inlet at one end, and a jet port at the other end. The mixture of hydrogen chloride and hydrofluoric acid is introduced into the air inlet. The jet port is connected to the upper portion of the mixing tank 4. An acid delivery pipe 6 is connected between the lower portion of the mixing tank 4 and the flow inlet, and an acid delivery pump 7 is mounted on the acid delivery pipe 6.

[0053] The mixing tank 4 is connected to the secondary mixing mechanism 8, which includes an acid addition chamber 9 and a gas mixing chamber 10. The acid addition chamber 9 is connected to the sulfuric acid absorption device 2 through the acid addition pipe 19. The gas mixing chamber 10 is connected to the injection port of the venturi injection pipe 5. The lower widths of the acid addition chamber 9 and the gas mixing chamber 10 gradually decrease from top to bottom so that the lower open end forms a water curtain notch 11. The center lines of the two water curtain notches 11 intersect below the water curtain notch 11. The acid addition chamber 9 and the gas mixing chamber 10 are arranged adjacent to each other. After the 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 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 with each other, further achieving mixing of sulfuric acid and mixed gas, improving the mixing effect, and improving the absorption effect of sulfuric acid on hydrofluoric acid.

[0054] The mixed gas discharged from the sulfuric acid jet vacuum unit 1 enters the sulfuric acid absorption device 2 through the air supply 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. 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.

[0055] The mixed acid is separated into sulfuric acid and hydrofluoric acid by using the saturated vapor pressure principle of hydrofluoric acid and sulfuric acid at different temperatures. The sulfuric acid is refluxed to the sulfuric acid jet vacuum unit 1 and the sulfuric acid absorption device 2 for reuse, and the hydrofluoric acid is recovered.

[0056] The sulfuric acid absorption unit 2 includes an upper spray cylinder 13 and a lower mixed acid liquid storage cylinder 14. A sulfuric acid spray pipe 15 is installed in the spray cylinder 13. The sulfuric acid spray pipe 15 is located above the spray cylinder 13, and the upper end of the spray cylinder 13 is connected to a hydrogen chloride recovery pipe 16. An air supply pipe 12 is connected between the lower portion of the spray pipe and the upper portion of the mixing tank 4 of the sulfuric acid injection vacuum unit 1. The mixed acid liquid storage cylinder 14 is connected to a liquid outlet pipe 17, on which a liquid feed pump 18 is installed. The liquid outlet pipe 17 is connected to an acid addition pipe 19 and a 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. The acid addition pipe 19 is connected to the upper portion of the mixing tank 4, and the liquid spray pipe 20 is connected to the spray pipe.

[0057] The sulfuric acid separation device 3 includes a separator 21 and a heat exchanger 22. The inlet of the heat exchanger 22 is connected to the bottom of the separator 21, and the outlet of the heat exchanger 22 is connected to the top of the separator 21. A circulation pump 23 is installed in the pipeline between the inlet of the heat exchanger 22 and the bottom of the separator 21. The top of the separator 21 is connected to a hydrofluoric acid recovery pipe 24. A primary dispersion plate 25 and a secondary dispersion packing section 26 are installed in the separator 21. The primary dispersion plate 25 is placed above the secondary dispersion packing section 26. A plurality of flow pipes 27 are evenly distributed on the primary dispersion plate 25. The upper ends of the flow pipes 27 are higher than the primary dispersion plate 25, and the upper ends of all the flow pipes 27 are flush.

[0058] 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. The sulfuric acid storage tank 29 is connected to the sulfuric acid absorption device 2 through the acid pipe 31.

[0059] A mixed acid pipe 30 is connected to the bottom of the mixing tank 4 of the sulfuric acid jet vacuum unit 1. A mixed acid reflux pump 32 is installed on the mixed acid pipe 30. The mixed acid reflux pump 32 extracts the mixed acid from 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 top of the separator tank 21. An acid inlet pump 34 is installed on the acid inlet pipe 33. The acid inlet pump 34 extracts the mixed acid from the mixed acid transfer tank 28 and transports it to the separator tank 21. The sulfuric acid storage tank 29 is connected to an acid outlet pipe 35, which 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 top of the mixed acid storage cylinder 14. An acid injection pump 36 is installed on the acid delivery pipe 31.

[0060] Separator 21 is connected to a vacuum unit 37 via a pipeline. This unit 37 evacuates separator 21, thereby lowering the temperature required for gaseous hydrofluoric acid separation and preventing excessive temperatures from affecting the corrosion resistance of separator 21. After the mixed acid is delivered to separator 21 via the acid inlet pump 34, the acid inlet pipe 33, the acid outlet pipe 35, and the hydrofluoric acid recovery pipe 24 are closed. The vacuum unit 37 is then activated to evacuate separator 21, reducing the pressure within separator 21. Once the pressure reaches the set point, the vacuum unit 37 is closed. The heat exchanger 22 and circulation pump 23 are then activated to separate the mixed acid within separator 21.

[0061] The sulfuric acid separation device 3 is connected to the hydrofluoric acid recovery device 38 via 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 a hydrofluoric acid storage tank 41 via a pipeline, and the liquid hydrofluoric acid is recovered in the hydrofluoric acid storage tank 41 for production.

[0062] Sulfuric acid absorption unit 2 is connected to hydrogen chloride falling film water absorption unit 42 via hydrogen chloride recovery pipe 16. Hydrogen chloride falling film water absorption unit 42 comprises a falling film absorption tower 43 and a liquid storage tank 44. Falling film absorption tower 43 is connected to the upper end of liquid storage tank 44, and hydrogen chloride recovery pipe 16 is connected to the top of falling film absorption tower 43. A reflux pipe 45 is installed between the top of falling film absorption tower 43 and the bottom of liquid storage tank 44. A reflux pump 46 is installed on reflux pipe 45. Reflux pump 46 extracts hydrochloric acid solution from liquid storage tank 44 and transports it to the top of falling film absorption tower 43 for absorption of gaseous hydrogen chloride. The liquid outlet of reflux pump 46 on reflux pipe 45 is connected to hydrochloric acid storage tank 47 via a pipeline. The hydrochloric acid in liquid storage tank 44 is transported to hydrochloric acid storage tank 47 for production.

[0063] 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 at the top of the alkali washing absorption tower 50. A reabsorption filler 55 and a nozzle 56 are installed near the top of the alkali washing absorption tower 50. The nozzle 56 is arranged below the reabsorption filler 55. The nozzle 56 is connected to the reabsorption pipe 52. The nozzle 56 sprays the reabsorption liquid downward.

[0064] A method for separating and purifying hydrogen chloride and hydrofluoric acid is operated using 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, the sulfuric acid in an acid feeding pipe 6 is transported to the inlet of a venturi injection pipe 5, a negative pressure is generated at the air inlet position, and the mixed gas is sucked into the venturi injection pipe 5 from the air inlet of the venturi injection pipe 5, so that the sulfuric acid and the mixed gas are mixed, and the sulfuric acid absorbs the hydrofluoric acid to form a mixed acid that is transported to a sulfuric acid separation device 3.

[0065] In step S2, the mixed gas output from the sulfuric acid jet vacuum unit 1 enters the sulfuric acid absorption unit 2 through the gas supply pipe 12, where it further mixes with sulfuric acid to absorb hydrofluoric acid, forming a mixed acid that is transported to the sulfuric acid separation unit 3, where the separated hydrogen chloride is recovered. The hydrogen chloride gas separated by the sulfuric acid absorption unit 2 is transported via the hydrogen chloride recovery pipe 16 to the falling film absorption tower 43 of the hydrogen chloride falling film water absorption unit 42. A reflux pump 46 draws hydrochloric acid solution from the liquid storage tank 44 and transports it to the top of the falling film absorption tower 43 for absorption of gaseous hydrogen chloride. The liquid outlet of the reflux pump 46 on the reflux pipe 45 is connected to the hydrochloric acid storage tank 47 via 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 gas discharge pipe 48 connects to the bottom of the alkaline wash absorption tower 50, where a spray pipe 56 sprays the reabsorbed liquid downward to absorb the residual gaseous hydrogen chloride.

[0066] In step S3, the mixed acid is decomposed in the sulfuric acid separation unit 3 to produce sulfuric acid and hydrofluoric acid. The sulfuric acid is refluxed to the sulfuric acid jet vacuum unit 1 and the sulfuric acid absorption unit 2 for reuse, while 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 then collected in the hydrofluoric acid receiving tank 40. The bottom of the hydrofluoric acid receiving tank 40 is connected to the hydrofluoric acid storage tank 41 via a pipeline, and the liquid hydrofluoric acid is recovered to the hydrofluoric acid storage tank 41 for use in production.

[0067] In this patent, sulfuric acid is first used to absorb the hydrofluoric acid in the hydrogen chloride and hydrofluoric acid mixed gas, thereby separating the hydrogen chloride, and then recovering the hydrogen chloride. The mixed acid formed after the sulfuric acid absorbs the hydrofluoric acid is separated by a sulfuric acid separation device 3. After the mixed acid is heated, the hydrofluoric acid gas can be separated and the hydrofluoric acid is recovered. The remaining sulfuric acid is reused. After the hydrogen chloride and hydrofluoric acid mixed gas passes through the hydrogen chloride and hydrofluoric acid separation and purification system, the hydrogen chloride and hydrofluoric acid can be separated. The sulfuric acid is recycled throughout the entire system, achieving the purpose of significantly reducing production costs.

[0068] The sulfuric acid jet vacuum unit 1 maintains a negative pressure at the front end of the unit and a positive pressure at the rear end, ensuring proper gas transport and flow. The unit's Venturi tube also provides mixing and absorption. Within the sulfuric acid absorption unit 2, secondary mixing occurs under the sulfuric acid spray, achieving complete separation of HF and HCl. The sulfuric acid mixes with the mixed gas, absorbing the HF to form a mixed acid. After heating in the sulfuric acid separation unit 3, the mixed acid separates the HF gas. The remaining sulfuric acid is then recycled back to the sulfuric acid jet vacuum unit 1 and sulfuric acid absorption unit 2 for reuse.

[0069] 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 being that in this embodiment, the secondary mixing mechanism 8 includes an acid addition chamber 9 and an air mixing chamber 10. The acid addition chamber 9 is connected to the sulfuric acid absorption device 2 through an acid addition pipe 19, and the air mixing chamber 10 is connected to the injection port of the venturi injection pipe 5. A plurality of sulfuric acid injection sleeves 57 are provided at the bottom of the acid addition chamber 9, and a plurality of air mixing injection sleeves 58 are provided at the bottom of the air mixing chamber 10. The air mixing injection sleeves 58 and the sulfuric acid injection sleeves 57 are provided in a one-to-one correspondence. The lower end of the air mixing injection sleeve 58 is placed in the sulfuric acid injection sleeve 57. The apertures of the air mixing injection sleeves 58 and the sulfuric acid injection sleeves 57 gradually decrease from top to bottom, and a gap is provided between the outer wall of the air mixing injection sleeve 58 and the inner wall of the sulfuric acid injection sleeve 57. The air mixing chamber 10 is provided in the acid addition chamber 9.

[0070] After the 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 from the acid addition tube 19 to the acid addition chamber 9 and ejected from the sulfuric acid injection sleeve 57 at the lower end of the acid addition 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 enhancing the absorption effect of the sulfuric acid on the hydrofluoric acid. The other structures are the same as those in Example 2.

[0071] 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: a mixture of sulfuric acid, hydrogen chloride and hydrofluoric acid is mixed in the sulfuric acid jet vacuum unit to absorb hydrofluoric acid to form mixed acid; Sulfuric acid absorption device: the mixed gas discharged from the sulfuric acid jet 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 sulfuric acid absorption device for reuse, and the hydrofluoric acid is recovered; 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 addition chamber and a gas mixing chamber. The acid addition chamber is connected to the sulfuric acid absorption device through the acid addition pipe. The gas mixing chamber is connected to the injection port of the Venturi injection pipe. The width of the lower parts of the acid addition chamber and the gas mixing chamber gradually decreases from top to bottom, so that the lower opening ends form a water curtain slot. The center lines of the two water curtain slots intersect below the water curtain slot. The sulfuric acid separation device includes a separation tank and a heat exchanger. 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. The heat exchanger heats the mixed acid in the separation tank. The separation tank is connected to the vacuum unit through a pipeline.

2. A system for separating and purifying hydrogen chloride and hydrofluoric acid according to claim 1, characterized in that: The sulfuric acid absorption device includes 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: A primary dispersion plate and a secondary dispersion filler section are installed in the separation tank. A plurality of flow pipes are evenly distributed on the primary dispersion plate, and the upper ends of the flow pipes are higher than the primary dispersion plate.

4. A system for separating and purifying hydrogen chloride and hydrofluoric acid according to claim 1, 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 jet vacuum unit through a mixed acid pipe. The sulfuric acid storage tank is connected to the sulfuric acid absorption device through an acid pipe.

5. 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.

6. A system for separating and purifying hydrogen chloride and hydrofluoric acid according to any one of claims 1 to 5, 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.

7. 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 6 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 from the sulfuric acid jet vacuum unit enters a sulfuric acid absorption device, is 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 reuse, and the hydrofluoric acid is recovered.

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