An application method for separating sulfur dioxide tail gas containing hydrogen chloride

Abstract

The invention relates to the technical field of tail gas treatment and discloses an application method for separating tail gas containing hydrogen chloride and sulfur dioxide. The method comprises the following steps: step 1: subjecting the tail gas containing hydrogen chloride and sulfur dioxide to pressure-swing liquefaction treatment to obtain liquefied sulfur dioxide and tail gas containing hydrogen chloride; step 2: subjecting the liquefied sulfur dioxide to reduced-pressure and temperature-raising distillation treatment to obtain sulfur dioxide gas; step 3: subjecting the tail gas containing hydrogen chloride in step 1 to membrane separation treatment to obtain separated tail gas and solvent-adsorbed hydrogen chloride; step 4: subjecting the solvent-adsorbed hydrogen chloride to desorption treatment to obtain hydrogen chloride gas and an adsorbent, and the adsorbent is refluxed to step 3 for standby use; and step 5: subjecting the hydrogen chloride gas in step 4 to condensation and liquefaction to obtain liquefied hydrogen chloride. The method uses a hollow composite membrane and an alcohol solvent to treat hydrogen chloride, has high hydrogen chloride selectivity and is recyclable, and the treated products are sulfur dioxide with a purity of 99.99% and hydrogen chloride with a purity of 99.9999%, with high product economic benefits.

Description

Technical Field

[0001] The invention relates to the technical field of tail gas treatment, in particular to an application method for separating tail gas containing hydrogen chloride and sulfur dioxide. Background Art

[0002] The tail gas containing hydrogen chloride and sulfur dioxide is a waste mixture produced in the chlorination and sulfonation processes. In addition to hydrogen chloride and sulfur dioxide, it also contains other mixed gases such as organic solvents, water, hydrogen, nitrogen, etc. If the above gases are directly released into the air, they will cause serious environmental pollution. Therefore, they need to be treated before they can be discharged.

[0003] Current methods for treating hydrogen chloride and sulfur dioxide tail gas primarily include pressure swing distillation to separate sulfur dioxide, alkaline absorption to produce salt, and falling film absorption to produce hydrochloric acid. For example, Publication No. CN104645785A discloses a method for separating and recovering a hydrogen chloride and sulfur dioxide mixed gas, which utilizes falling film absorption and alkaline absorption to convert the mixed gas into 30% hydrochloric acid and sodium bisulfite. Another example is Publication No. CN109205573A, which discloses a highly efficient process for separating and utilizing tail gas from an acyl chloride reaction. This process utilizes pressure swing distillation and falling film absorption to separate hydrogen chloride and sulfur dioxide gas, resulting in high-purity sulfur dioxide gas and 30% hydrochloric acid. Currently, the primary product obtained from industrial treatment of hydrogen chloride and sulfur dioxide tail gas is 30% hydrochloric acid, but the resulting hydrochloric acid is low in concentration and contains impurities, resulting in extremely low economic value. Therefore, further optimization of the hydrogen chloride gas separation process is needed to produce a more economically efficient treated product. Summary of the Invention

[0004] In order to overcome the problems of poor quality and low economic benefits of hydrogen chloride-containing sulfur dioxide tail gas treatment products in the prior art, the present application provides an application method for separating hydrogen chloride-containing sulfur dioxide tail gas. In this method, sulfur dioxide gas is liquefied and separated by pressure swing liquefaction, and high-purity sulfur dioxide gas is produced by reduced pressure and temperature distillation. The hydrogen chloride-containing tail gas from which sulfur dioxide is separated is then subjected to membrane separation and purification to obtain solvent-adsorbed hydrogen chloride. The solvent-adsorbed hydrogen chloride is then desorbed to obtain high-purity hydrogen chloride gas. The high-purity hydrogen chloride gas is then liquefied and stored. This method can obtain high-purity sulfur dioxide and high-purity hydrogen chloride products with high product quality and good economic benefits. The solvent used in the hydrogen chloride treatment process can be recycled, and the treatment cost is low and environmentally friendly.

[0005] The specific technical solutions of the present invention are:

[0006] An application method for separating sulfur dioxide tail gas containing hydrogen chloride comprises the following steps:

[0007] Step 1: subjecting hydrogen chloride and sulfur dioxide tail gas to pressure-swing liquefaction treatment to obtain liquefied sulfur dioxide and hydrogen chloride-containing tail gas;

[0008] Step 2: subjecting the liquefied sulfur dioxide to a vacuum-heated distillation treatment to obtain sulfur dioxide gas;

[0009] Step 3: subjecting the hydrogen chloride-containing tail gas in step 1 to membrane separation treatment to obtain separated tail gas and solvent-absorbed hydrogen chloride;

[0010] Step 4: desorbing the hydrogen chloride adsorbed by the solvent to produce hydrogen chloride gas and an adsorbent, and the adsorbent is refluxed to step 3 for standby use;

[0011] Step 5: Condensing and liquefying the hydrogen chloride gas in step 4 to obtain liquefied hydrogen chloride.

[0012] The present application provides an application method for separating sulfur dioxide tail gas containing hydrogen chloride. In this method, a high-purity sulfur dioxide product can be obtained through pressure swing liquefaction and reduced pressure and temperature distillation. The purity of the obtained sulfur dioxide product can reach 99.99%. This method can obtain a high-purity hydrogen chloride product through membrane separation treatment. At the same time, the solvent in the membrane treatment process can be recycled, the production cost is reduced, and no other by-products are produced during production. The process is more environmentally friendly. The purity of the obtained hydrogen chloride product can reach 99.9999%. The product obtained by the above method has high purity, high quality and good economic benefits.

[0013] Preferably, the conditions for the pressure swing liquefaction treatment in step 1 include: a temperature of -2 to -10°C and a pressure of 2 to 2.5 MPa.

[0014] Preferably, the reduced pressure and temperature treatment in step 2 includes a primary distillation, a secondary distillation, and a tertiary distillation in sequence; the conditions of the primary distillation are: a temperature of 13-15° C. and a pressure of 3-3.5 MPa;

[0015] The conditions of the secondary distillation are: temperature 35-45°C, pressure 1.5-2MPa;

[0016] The conditions for the three distillations are: temperature 65-67° C., and pressure 1-1.25 MPa.

[0017] Preferably, the membrane separation treatment in step 3 includes the following steps: passing the hydrogen chloride-containing tail gas into a membrane separation device, the hollow fiber membrane separation device includes a hollow composite membrane and a shell sleeved on the outside of the hollow membrane, the hydrogen chloride-containing tail gas flows inside the hollow composite fiber membrane, the solvent flows between the cavity formed by the hollow composite membrane and the shell, and the solvent adsorbs the hydrogen chloride that permeates the outside of the hollow composite membrane to produce solvent-adsorbed hydrogen chloride.

[0018] The present application discloses a membrane separation method for separating hydrogen chloride tail gas. The device employed in this method is a hollow fiber membrane separation device. Currently, distillation separation is the main method used to separate hydrogen chloride. However, the present application has discovered that because the hydrogen chloride-containing tail gas also contains organic gases, the purity of the hydrogen chloride obtained by distillation cannot meet the purity standard of ultrapure hydrogen chloride. Therefore, in order to obtain an ultrapure hydrogen chloride product with a purity of 99.9999%, the present application employs a hollow fiber membrane separation device. The device comprises a hollow composite membrane and a shell disposed outside the hollow membrane. The hollow composite membrane selectively allows hydrogen chloride to permeate to the other side of the membrane, allowing the hydrogen chloride-containing tail gas to be separated to the other side of the membrane. Simultaneously, the solvent of the present application flows within the cavity formed by the hollow composite membrane and the shell. After the hydrogen chloride selectively permeates to the other side of the membrane, it is absorbed by the solvent on the other side to form solvent-adsorbed hydrogen chloride, thereby achieving the technical effect of separating the hydrogen chloride.

[0019] Preferably, the flow rate of the hydrogen chloride-containing tail gas is 5 to 7 mL / s, and the flow rate of the solvent is 1 to 3 mL / s;

[0020] Preferably, the hollow composite membrane comprises an organic silicon hollow fiber-based membrane and a permeable membrane coated on the inner surface of the organic silicon hollow fiber-based membrane; the molecular weight of the permeable membrane is 20,000 to 40,000, and the permeable membrane is selected from one of a polyimide membrane and a polyethersulfone membrane; the thickness of the permeable membrane is 2 to 3 μm.

[0021] The hollow composite membrane of the present application is composed of an organic silicon hollow fiber base membrane and a permeable membrane on the inner surface of the base membrane. First, when selecting the membrane material, the present application takes into account that the exhaust gas contains highly corrosive substances such as hydrogen chloride, and a membrane material with corrosion resistance is needed. Therefore, the present application finally selected an organic silicon hollow fiber membrane as the base membrane, but the present application found that the organic silicon hollow fiber membrane has no selectivity for hydrogen chloride gas and cannot selectively separate hydrogen chloride. To solve the above problem, the present application obtains a hollow composite membrane structure by compounding a layer of permeable membrane that can selectively permeate hydrogen chloride on the inner surface of the organic silicon hollow fiber base membrane, and by compounding an organic permeable membrane on the surface of an inorganic base membrane. Since the exhaust gas containing hydrogen chloride flows inside the hollow composite membrane of the present application, and the solvent flows outside the hollow composite membrane, the solvent will corrode the outer membrane structure after absorbing hydrogen chloride. The organic silicon hollow fiber membrane of the present application can play its corrosion-resistant role and improve the durability of the membrane.

[0022] Preferably, the solvent is selected from one or both of ethylene glycol and glycerol.

[0023] The solvent of the present application is an alcohol substance such as ethylene glycol and propylene glycol. The present application has found that hydrogen chloride has a large solubility in alcohol substances. At the same time, the alcohol substance will not chemically react with hydrogen chloride after dissolving hydrogen chloride, and hydrogen chloride can be desorbed from the alcohol substance by heating and distillation. The desorbed solvent can also be returned to the hollow fiber membrane separation device for practical circulation, which significantly reduces the production cost. At the same time, no other by-products are produced, which is more environmentally friendly. In addition, since the alcohol solvent has a strong hydrophilicity and the silicone hollow fiber membrane has a weak hydrophilicity, when the solvent flows on the silicone hollow fiber membrane, the solvent will not enter the gaps inside the silicone hollow fiber membrane.

[0024] Preferably, the pore size of the organosilicon hollow fiber membrane is 4 to 15 nm, and the thickness is 50 to 100 μm.

[0025] The present invention found that the selection of the pore size and thickness of the organosilicon hollow fiber membrane can promote the efficiency of hydrogen chloride permeation separation when preparing the hollow composite membrane. Since the hollow fiber membrane structure of the present invention is an organosilicon base membrane and a permeable membrane on the inner surface of the organosilicon, the separation process of hydrogen chloride is as follows: the hydrogen chloride in the hydrogen chloride-containing tail gas is first selectively separated by the permeable membrane, and the separated hydrogen chloride enters the membrane pores of the organosilicon hollow fiber membrane and accumulates in the membrane pores. When the hydrogen chloride contacts the solvent flowing outside the organosilicon membrane, it will be rapidly adsorbed by the solvent. After the hydrogen chloride is adsorbed, it is absorbed by the organosilicon. Negative pressure will be formed inside the voids of the hollow fiber, causing a pressure difference on both sides of the permeable membrane, thereby accelerating the permeation efficiency of hydrogen chloride. The present application found that the pore size and thickness of the organosilicon hollow fiber will have a great influence on the generated negative pressure. When the thickness is low, the structural strength of the base membrane is weak. When the thickness is large, the accumulation time of hydrogen chloride in the organosilicon hollow fiber membrane increases, slowing down the adsorption of hydrogen chloride by the solvent and slowing down the adsorption efficiency. If the pore size is too small, hydrogen chloride cannot enter the voids of the organosilicon hollow fiber membrane. At the same time, the present application found that when the pore size is too large, the permeation efficiency of the permeable membrane is not significantly improved.

[0026] Preferably, the desorption treatment conditions in step 5 include: a distillation temperature of 135 to 140° C. and a distillation time of 45 to 60 minutes.

[0027] The desorption effect of the solvent of the present application is better when the desorption temperature is above 135° C., and the desorbed hydrogen chloride can reach 95% when the distillation time is within 45 minutes.

[0028] Preferably, the condensation and liquefaction temperature is -85 to -100°C.

[0029] Compared with the existing technology, this application has the following technical effects:

[0030] (1) The product of the separation of hydrogen chloride-containing sulfur dioxide tail gas in this application is 99.99% pure sulfur dioxide and 99.9999% pure hydrogen chloride, and the product has high economic benefits;

[0031] (2) In the present application, a hollow fiber membrane separation device is used for hydrogen chloride separation. The hollow fiber membrane separation device uses a composite hollow membrane formed by an organic silicon hollow fiber base membrane and a permeable membrane coated on the inner surface of the organic silicon hollow fiber base membrane. The solvent used is an alcohol solvent of ethylene glycol and propylene glycol. The use of the above device can selectively separate hydrogen chloride. At the same time, the corrosion resistance and durability of the membrane are high. In addition, the alcohol can be recycled as a solvent after desorption. The efficiency of separating hydrogen chloride is high, there are no other by-products, the cost is low, and it is environmentally friendly.

[0032] (3) This application defines the structure of the hollow composite membrane. The pore size and thickness of the organosilicon hollow fiber membrane can affect the permeation efficiency of hydrogen chloride and can promote the permeation efficiency of hydrogen chloride within a certain range. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the embodiments.

[0034] Example 1:

[0035] An application method for separating sulfur dioxide tail gas containing hydrogen chloride is characterized by comprising the following steps:

[0036] Step 1: subjecting the hydrogen chloride and sulfur dioxide tail gas to pressure swing liquefaction treatment to produce liquefied sulfur dioxide and hydrogen chloride-containing tail gas, wherein the pressure swing liquefaction treatment conditions include: temperature of -2°C and pressure of 2 MPa;

[0037] Step 2: subjecting the liquefied sulfur dioxide to a vacuum-heated distillation treatment to obtain sulfur dioxide gas, wherein the vacuum-heated distillation treatment includes a primary distillation, a secondary distillation, and a tertiary distillation;

[0038] The conditions for primary distillation are: temperature 13°C, pressure 3 MPa;

[0039] The conditions for secondary distillation are: temperature 35°C, pressure 1.5 MPa;

[0040] The conditions for the tertiary distillation were: temperature 65°C, pressure 1 MPa;

[0041] Step 3: subjecting the hydrogen chloride-containing tail gas in step 1 to membrane separation treatment to produce separated tail gas and solvent-adsorbed hydrogen chloride, the membrane separation treatment comprising the following steps: passing the hydrogen chloride-containing tail gas into a membrane separation device, the hollow fiber membrane separation device comprising a hollow composite membrane and a shell sleeved on the outside of the hollow membrane, the hydrogen chloride-containing tail gas flowing inside the hollow composite fiber membrane, the solvent flowing between the cavity formed by the hollow composite membrane and the shell, and the solvent adsorbing and permeating the hydrogen chloride on the outside of the hollow composite membrane to produce solvent-adsorbed hydrogen chloride; the flow rate of the hydrogen chloride-containing tail gas is 5 mL / s, the flow rate of the solvent is 1 mL / s, the hollow composite membrane comprises an organosilicon hollow fiber base membrane and a permeable membrane coated on the inner surface of the organosilicon hollow fiber base membrane; the permeable membrane is a polyimide membrane, the molecular weight of the polyimide is 30,000, the thickness of the permeable membrane is 2.5 μm, the solvent is ethylene glycol, the pore size of the organosilicon hollow fiber membrane is 4 nm, and the thickness is 50 μm;

[0042] Step 4: Desorbing the hydrogen chloride adsorbed by the solvent to produce hydrogen chloride gas and an adsorbent, and returning the adsorbent to step 3 for standby use. The desorption treatment conditions include: a distillation temperature of 135° C. and a distillation time of 45 minutes.

[0043] Step 5: Condensing and liquefying the hydrogen chloride gas in step 4 to obtain liquefied hydrogen chloride.

[0044] Example 2:

[0045] An application method for separating sulfur dioxide tail gas containing hydrogen chloride is characterized by comprising the following steps:

[0046] Step 1: subjecting the hydrogen chloride and sulfur dioxide tail gas to pressure swing liquefaction treatment to produce liquefied sulfur dioxide and hydrogen chloride-containing tail gas, wherein the pressure swing liquefaction treatment conditions include: temperature of -6°C and pressure of 2.25 MPa;

[0047] Step 2: subjecting the liquefied sulfur dioxide to a vacuum-heated distillation treatment to obtain sulfur dioxide gas, wherein the vacuum-heated distillation treatment includes a primary distillation, a secondary distillation, and a tertiary distillation;

[0048] The conditions for the primary distillation were: temperature 14°C, pressure 3.25 MPa;

[0049] The conditions for secondary distillation are: temperature 40°C, pressure 1.75 MPa;

[0050] The conditions for the tertiary distillation were: temperature 66°C, pressure 1.15 MPa;

[0051] Step 3: subjecting the hydrogen chloride-containing tail gas in step 1 to membrane separation treatment to produce separated tail gas and solvent-adsorbed hydrogen chloride, the membrane separation treatment comprising the following steps: passing the hydrogen chloride-containing tail gas into a membrane separation device, the hollow fiber membrane separation device comprising a hollow composite membrane and a shell sleeved on the outside of the hollow membrane, the hydrogen chloride-containing tail gas flowing inside the hollow composite fiber membrane, the solvent flowing between the cavity formed by the hollow composite membrane and the shell, and the solvent adsorbing and permeating the hydrogen chloride on the outside of the hollow composite membrane to produce solvent-adsorbed hydrogen chloride; the flow rate of the hydrogen chloride-containing tail gas is 6 mL / s, the flow rate of the solvent is 2 mL / s, the hollow composite membrane comprises an organosilicon hollow fiber base membrane and a permeable membrane coated on the inner surface of the organosilicon hollow fiber base membrane; the permeable membrane is a polyimide membrane, the molecular weight of the polyimide is 30,000, the thickness of the permeable membrane is 2.5 μm, the solvent is ethylene glycol, the pore size of the organosilicon hollow fiber membrane is 8 nm, and the thickness is 80 μm;

[0052] Step 4: Desorbing the hydrogen chloride adsorbed by the solvent to produce hydrogen chloride gas and an adsorbent, and returning the adsorbent to step 3 for standby use. The desorption treatment conditions include: a distillation temperature of 137° C. and a distillation time of 55 minutes.

[0053] Step 5: Condensing and liquefying the hydrogen chloride gas in step 4 to obtain liquefied hydrogen chloride.

[0054] Example 3:

[0055] An application method for separating sulfur dioxide tail gas containing hydrogen chloride is characterized by comprising the following steps:

[0056] Step 1: subjecting the hydrogen chloride and sulfur dioxide tail gas to pressure swing liquefaction treatment to produce liquefied sulfur dioxide and hydrogen chloride-containing tail gas, wherein the pressure swing liquefaction treatment conditions include: temperature of -10°C and pressure of 2.5 MPa;

[0057] Step 2: subjecting the liquefied sulfur dioxide to a vacuum-heated distillation treatment to obtain sulfur dioxide gas, wherein the vacuum-heated distillation treatment includes a primary distillation, a secondary distillation, and a tertiary distillation;

[0058] The conditions for primary distillation are: temperature 15°C, pressure 3.5 MPa;

[0059] The conditions for secondary distillation are: temperature 45°C, pressure 2 MPa;

[0060] The conditions for the tertiary distillation were: temperature 67 °C, pressure 1.25 MPa;

[0061] Step 3: subjecting the hydrogen chloride-containing tail gas in step 1 to membrane separation treatment to produce separated tail gas and solvent-absorbed hydrogen chloride, the membrane separation treatment comprising the following steps: passing the hydrogen chloride-containing tail gas into a membrane separation device, the hollow fiber membrane separation device comprising a hollow composite membrane and a shell sleeved on the outside of the hollow membrane, the hydrogen chloride-containing tail gas flowing inside the hollow composite fiber membrane, the solvent flowing between the cavity formed by the hollow composite membrane and the shell, and the solvent adsorbing and permeating the hydrogen chloride on the outside of the hollow composite membrane to produce solvent-absorbed hydrogen chloride; the flow rate of the hydrogen chloride-containing tail gas is 5-7 mL / s, the flow rate of the solvent is 1-3 mL / s, the hollow composite membrane comprises an organic silicon hollow fiber base membrane and a permeable membrane coated on the inner surface of the organic silicon hollow fiber base membrane; the permeable membrane is a polyimide membrane, the molecular weight of the polyimide is 30,000, the thickness of the permeable membrane is 2.5 μm, the solvent is ethylene glycol, the pore size of the organic silicon hollow fiber membrane is 15 nm, and the thickness is 100 μm;

[0062] Step 4: Desorbing the hydrogen chloride adsorbed by the solvent to produce hydrogen chloride gas and an adsorbent, and returning the adsorbent to step 3 for standby use. The desorption treatment conditions include: a distillation temperature of 135-140° C. and a distillation time of 45-60 min.

[0063] Step 5: Condensing and liquefying the hydrogen chloride gas in step 4 to obtain liquefied hydrogen chloride.

[0064] Example 4:

[0065] Step 1: subjecting the hydrogen chloride and sulfur dioxide tail gas to pressure swing liquefaction treatment to produce liquefied sulfur dioxide and hydrogen chloride-containing tail gas, wherein the pressure swing liquefaction treatment conditions include: temperature of -2°C and pressure of 2 MPa;

[0066] Step 2: subjecting the liquefied sulfur dioxide to a vacuum-heated distillation treatment to obtain sulfur dioxide gas, wherein the vacuum-heated distillation treatment includes a primary distillation, a secondary distillation, and a tertiary distillation;

[0067] The conditions for primary distillation are: temperature 13°C, pressure 3 MPa;

[0068] The conditions for secondary distillation are: temperature 35°C, pressure 1.5 MPa;

[0069] The conditions for the tertiary distillation were: temperature 65°C, pressure 1 MPa;

[0070] Step 3: subjecting the hydrogen chloride-containing tail gas in step 1 to membrane separation treatment to produce separated tail gas and solvent-absorbed hydrogen chloride, the membrane separation treatment comprising the following steps: passing the hydrogen chloride-containing tail gas into a membrane separation device, the hollow fiber membrane separation device comprising a hollow composite membrane and a shell sleeved on the outside of the hollow membrane, the hydrogen chloride-containing tail gas flowing inside the hollow composite fiber membrane, the solvent flowing between the cavity formed by the hollow composite membrane and the shell, and the solvent adsorbing and permeating the hydrogen chloride on the outside of the hollow composite membrane to produce solvent-absorbed hydrogen chloride; the flow rate of the hydrogen chloride-containing tail gas is 5-7 mL / s, the flow rate of the solvent is 1-3 mL / s, the hollow composite membrane comprises an organosilicon hollow fiber base membrane and a permeable membrane coated on the inner surface of the organosilicon hollow fiber base membrane; the permeable membrane is a polyethersulfone membrane, the molecular weight of the polyethersulfone is 32571, the thickness of the permeable membrane is 2 μm, the solvent is ethylene glycol, the pore size of the organosilicon hollow fiber membrane is 4 nm, and the thickness is 50 μm;

[0071] Step 4: Desorbing the hydrogen chloride adsorbed by the solvent to produce hydrogen chloride gas and an adsorbent, and returning the adsorbent to step 3 for standby use. The desorption treatment conditions include: a distillation temperature of 135° C. and a distillation time of 45 minutes.

[0072] Step 5: Condensing and liquefying the hydrogen chloride gas in step 4 to obtain liquefied hydrogen chloride.

[0073] Example 5:

[0074] Step 1: subjecting the hydrogen chloride and sulfur dioxide tail gas to pressure swing liquefaction treatment to produce liquefied sulfur dioxide and hydrogen chloride-containing tail gas, wherein the pressure swing liquefaction treatment conditions include: temperature of -2°C and pressure of 2.5 MPa;

[0075] Step 2: subjecting the liquefied sulfur dioxide to a vacuum-heated distillation treatment to obtain sulfur dioxide gas, wherein the vacuum-heated distillation treatment includes a primary distillation, a secondary distillation, and a tertiary distillation;

[0076] The conditions for primary distillation are: temperature 15°C, pressure 3.5 MPa;

[0077] The conditions for secondary distillation are: temperature 45°C, pressure 2 MPa;

[0078] The conditions for the tertiary distillation were: temperature 67 °C, pressure 1.25 MPa;

[0079] Step 3: subjecting the hydrogen chloride-containing tail gas in step 1 to membrane separation treatment to produce separated tail gas and solvent-absorbed hydrogen chloride, the membrane separation treatment comprising the following steps: passing the hydrogen chloride-containing tail gas into a membrane separation device, the hollow fiber membrane separation device comprising a hollow composite membrane and a shell sleeved on the outside of the hollow membrane, the hydrogen chloride-containing tail gas flowing inside the hollow composite fiber membrane, the solvent flowing between the cavity formed by the hollow composite membrane and the shell, and the solvent adsorbing and permeating the hydrogen chloride on the outside of the hollow composite membrane to produce solvent-absorbed hydrogen chloride; the flow rate of the hydrogen chloride-containing tail gas is 5-7 mL / s, the flow rate of the solvent is 1-3 mL / s, the hollow composite membrane comprises an organic silicon hollow fiber base membrane and a permeable membrane coated on the inner surface of the organic silicon hollow fiber base membrane, the permeable membrane is a polyethersulfone membrane, the molecular weight of the polyethersulfone is 31200, the thickness of the permeable membrane is 3 μm, the solvent is ethylene glycol, the pore size of the organic silicon hollow fiber membrane is 15 nm, and the thickness is 100 μm;

[0080] Step 4: Desorbing the hydrogen chloride adsorbed by the solvent to produce hydrogen chloride gas and an adsorbent, and returning the adsorbent to step 3 for standby use. The desorption treatment conditions include: a distillation temperature of 135-140° C. and a distillation time of 45-60 min.

[0081] Step 5: Condensing and liquefying the hydrogen chloride gas in step 4 to obtain liquefied hydrogen chloride.

[0082] Example 6:

[0083] Step 1: subjecting the hydrogen chloride and sulfur dioxide tail gas to pressure swing liquefaction treatment to produce liquefied sulfur dioxide and hydrogen chloride-containing tail gas, wherein the pressure swing liquefaction treatment conditions include: temperature of -2°C and pressure of 2 MPa;

[0084] Step 2: subjecting the liquefied sulfur dioxide to a vacuum-heated distillation treatment to obtain sulfur dioxide gas, wherein the vacuum-heated distillation treatment includes a primary distillation, a secondary distillation, and a tertiary distillation;

[0085] The conditions for primary distillation are: temperature 13°C, pressure 3 MPa;

[0086] The conditions for secondary distillation are: temperature 35°C, pressure 1.5 MPa;

[0087] The conditions for the tertiary distillation were: temperature 65°C, pressure 1 MPa;

[0088] Step 3: subjecting the hydrogen chloride-containing tail gas in step 1 to membrane separation treatment to produce separated tail gas and solvent-absorbed hydrogen chloride, the membrane separation treatment comprising the following steps: passing the hydrogen chloride-containing tail gas into a membrane separation device, the hollow fiber membrane separation device comprising a hollow composite membrane and a shell sleeved on the outside of the hollow membrane, the hydrogen chloride-containing tail gas flowing inside the hollow composite fiber membrane, the solvent flowing between the cavity formed by the hollow composite membrane and the shell, and the solvent adsorbing and permeating the hydrogen chloride on the outside of the hollow composite membrane to produce solvent-absorbed hydrogen chloride; the flow rate of the hydrogen chloride-containing tail gas is 5 mL / s, the flow rate of the solvent is 3 mL / s, the hollow composite membrane comprises an organic silicon hollow fiber base membrane and a permeable membrane coated on the inner surface of the organic silicon hollow fiber base membrane; the permeable membrane is a polyimide membrane, the molecular weight of the polyimide is 30,000, the thickness of the permeable membrane is 2.5 μm, the solvent is glycerol, the pore size of the organic silicon hollow fiber membrane is 4 to 15 nm, and the thickness is 50 to 100 μm;

[0089] Step 4: Desorbing the hydrogen chloride adsorbed by the solvent to produce hydrogen chloride gas and an adsorbent, and returning the adsorbent to step 3 for standby use. The desorption treatment conditions include: a distillation temperature of 140° C. and a distillation time of 60 minutes.

[0090] Step 5: Condensing and liquefying the hydrogen chloride gas in step 4 to obtain liquefied hydrogen chloride.

[0091] Comparative Example 1: (pore size too large)

[0092] Compared with Example 1, Comparative Example 1 used an organosilicon hollow fiber membrane with a pore size of 18 nm, and other conditions were the same as those in Example 1.

[0093] Comparative Example 2: (pore size too small)

[0094] Compared with Example 1, Comparative Example 1 used an organosilicon hollow fiber membrane with a pore size of 2 nm, and the other conditions were the same as those of Example 1.

[0095] Comparative Example 3: (Thickness is too large)

[0096] Compared with Example 1, Comparative Example 1 used an organosilicon hollow fiber membrane with a thickness of 150 μm, and other conditions were the same as those in Example 1.

[0097] Comparative Example 4: (Thickness too small)

[0098] Compared with Example 1, Comparative Example 1 used an organosilicon hollow fiber membrane with a thickness of 20 μm, and other conditions were the same as those in Example 1.

[0099] Comparative Example 5: (Hollow fiber membrane is polyimide membrane)

[0100] Compared with Example 1, in Comparative Example 5, the hollow fiber membrane in the hollow fiber membrane device is a polyimide membrane, and the other conditions are the same as those in Example 1.

[0101] Comparative Example 6: (Hollow fiber membrane using polyethersulfone membrane)

[0102] Compared with Example 1, in Comparative Example 5, the hollow fiber membrane in the hollow fiber membrane device is a polyethersulfone membrane, and the other conditions are the same as those in Example 1.

[0103] Test example:

[0104] The purity of the products prepared in Examples 1 to 6 was tested, and the test results were

[0105]

[0106]

[0107] As shown in Table 1, the product obtained by the method of the present application has good initial quality, the purity of sulfur dioxide can reach 99.99%, and the purity of hydrogen chloride can reach 99.9999%, with extremely high economic value. In addition, the solvents used are ethylene glycol and propylene glycol solutions, which are safe and can be recycled, without producing any by-products, and are low in cost and environmentally friendly.

[0108] The membrane permeability of Examples 1 to 3 and Comparative Examples 1 to 6 was tested. The test process was as follows: the tail gas containing hydrogen chloride was introduced into the hollow membrane fiber device. After separation for 2 hours, all the hydrogen chloride in the solvent was desorbed. The desorbed hydrogen chloride was titrated with an alkali titration method to determine the content of separated hydrogen chloride. The permeability of hydrogen chloride per unit time (mol / h·m 2 ).

[0109] project <![CDATA[Permeability (mol / h·m 2 )]]> Example 1 The pore size of the organic silicon hollow fiber membrane is 4nm and the thickness is 50μm 12.02 Example 2 The pore size of the organosilicon hollow fiber membrane is 8nm and the thickness is 80μm 12.26 Example 3 The pore size of the organosilicon hollow fiber membrane is 15nm and the thickness is 100μm 12.13 Comparative Example 1 The pore size of the organosilicon hollow fiber membrane is 18nm 11.98 Comparative Example 2 The pore size of the organosilicon hollow fiber membrane is 2nm 0 Comparative Example 3 The thickness of the silicone hollow fiber membrane is 150 μm 10.35 Comparative Example 4 The thickness of the silicone hollow fiber membrane is 20 μm 11.34 Comparative Example 5 Hollow fiber membrane is polyimide membrane 11.28 Comparative Example 6 Hollow fiber membrane is polyethersulfone membrane 11.32

[0110] As shown in Table 2, in the above test results, the present application defines the pore size and thickness of the organosilicon hollow fiber membrane. Through the analysis of the permeability results of Examples 1 to 3, when the pore size and thickness of the organosilicon hollow fiber membrane are within the range defined in this application, the permeation separation rate of hydrogen chloride will first increase and then decrease, and the maximum permeability peak will appear within the application range. When the pore size of the organosilicon hollow fiber membrane in Comparative Example 1 is too large, the permeability is improved compared with the direct use of polyimide membrane and polyethersulfone membrane (Comparative Examples 5 and 6), but the improvement is not large. When the pore size of the organosilicon hollow fiber membrane is too small, hydrogen chloride cannot permeate. In addition, when the thickness of the organosilicon hollow fiber membrane is too large, the permeability of hydrogen chloride decreases, while when the thickness of the organosilicon hollow fiber membrane is too small, the permeability of hydrogen chloride does not increase. From the above results, it can be seen that the selection of the pore size and thickness of the organosilicon hollow fiber membrane within a certain range can promote the permeability of hydrogen chloride.

[0111] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. An application method for separating sulfur dioxide tail gas containing hydrogen chloride, characterized in that: The following steps are involved: Step 1: subjecting hydrogen chloride and sulfur dioxide tail gas to pressure-swing liquefaction treatment to obtain liquefied sulfur dioxide and hydrogen chloride-containing tail gas; Step 2: subjecting the liquefied sulfur dioxide to a vacuum-heated distillation treatment to obtain sulfur dioxide gas; Step 3: subjecting the hydrogen chloride-containing tail gas in step 1 to membrane separation treatment to obtain separated tail gas and solvent-absorbed hydrogen chloride; The membrane separation process uses a hollow fiber membrane separation device, which includes a hollow composite membrane and a shell sleeved on the outside of the hollow composite membrane. The hollow composite membrane includes an organic silicon hollow fiber base membrane and a permeable membrane coated on the inner surface of the organic silicon hollow fiber base membrane. The permeable membrane is a polyimide membrane or a polyethersulfone membrane. The molecular weight of the permeable membrane is 20,000~40,000, and the thickness is 2~3μm; The pore size of the organosilicon hollow fiber membrane is 4~15nm and the thickness is 50~100μm; Step 4: desorbing the hydrogen chloride adsorbed by the solvent to produce hydrogen chloride gas and an adsorbent, and the adsorbent is refluxed to step 3 for standby use; Step 5: Condensing and liquefying the hydrogen chloride gas in step 4 to obtain liquefied hydrogen chloride.

2. The application method according to claim 1, characterized in that: The conditions of the pressure swing liquefaction treatment in step 1 include: a temperature of -2 to -10°C and a pressure of 2 to 2.5 MPa.

3. The application method according to claim 1, characterized in that: The reduced pressure and temperature treatment in step 2 includes a primary distillation, a secondary distillation, and a tertiary distillation in sequence; The conditions of the primary distillation are: temperature 13-15°C, pressure 3-3.5 MPa; The conditions of the secondary distillation are: temperature 35-45°C, pressure 1.5-2MPa; The conditions for the three distillations are: temperature 65-67° C., and pressure 1-1.25 MPa.

4. The application method according to claim 1, characterized in that: The membrane separation treatment in step 3 includes the following steps: passing the hydrogen chloride-containing tail gas into a membrane separation device, the hollow fiber membrane separation device includes a hollow composite membrane and a shell sleeved on the outside of the hollow membrane, the hydrogen chloride-containing tail gas flows inside the hollow composite fiber membrane, the solvent flows between the cavity formed by the hollow composite membrane and the shell, and the solvent adsorbs the hydrogen chloride that permeates the outside of the hollow composite membrane to produce solvent-adsorbed hydrogen chloride.

5. The application method according to claim 4, wherein: The flow rate of the hydrogen chloride-containing tail gas is 5-7 mL / s, and the flow rate of the solvent is 1-3 mL / s.

6. The application method according to claim 4, characterized in that: The solvent is selected from one or both of ethylene glycol and glycerol.

7. The application method according to claim 1, characterized in that: The conditions for the desorption treatment in step 5 include: a distillation temperature of 135-140° C. and a distillation time of 45-60 min.

8. The application method according to claim 1, characterized in that: The condensation and liquefaction temperature is -85~-100℃.

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