Gas purification method

Abstract

The invention provides a gas purification method, and belongs to the technical field of purification. The gas purification method provided by the invention comprises the following steps: purifying gas to be treated by adopting a recrystallized silicon carbide gas filtering membrane to obtain purified gas; the preparation method of the recrystallized silicon carbide gas filtering membrane comprises the following steps: mixing silicon carbide, cellulose, glucan, vegetable oil, glycerol and water, and kneading to obtain a kneaded material; sequentially carrying out extrusion molding, drying and degumming on the kneaded material to obtain a degummed green body; and carrying out sintering-coating treatment on the degummed green body to obtain the recrystallized silicon carbide gas filtering membrane. The recrystallized silicon carbide gas filtering membrane is used for purifying to-be-treated gas, and the recrystallized silicon carbide gas filtering membrane is resistant to acid, alkali and high temperature and facilitates direct purification of corrosive high-temperature gas.

Description

Technical Field

[0001] The present invention relates to the field of purification technology, and in particular to a gas purification method. Background Art

[0002] With the development of industry, the gases produced in many production processes contain certain toxic and harmful components, which need to be purified for subsequent processes or discharge. Using filter membranes to purify gases is easy to operate and has a wide range of applications.

[0003] At present, the filter membranes used for gas purification are mainly organic polymer gas filter membranes, such as polytetrafluoroethylene (PTFE) membranes or polyvinylidene fluoride (PVDF) membranes. Organic polymer gas filter membranes have good acid and alkali resistance, but are not resistant to high temperatures. Usually, the gas needs to be cooled rapidly before processing, which wastes energy. Summary of the invention

[0004] The object of the present invention is to provide a gas purification method. The present invention uses a recrystallized silicon carbide gas filter membrane to purify the gas to be treated. The silicon carbide gas filter membrane is resistant to acid, alkali and high temperature, and is convenient for directly purifying corrosive high-temperature gas.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a gas purification method, comprising the following steps: The gas to be treated is purified by using a recrystallized silicon carbide gas filter membrane to obtain purified gas; The method for preparing the recrystallized silicon carbide gas filtration membrane comprises the following steps: Silicon carbide, cellulose, dextran, vegetable oil, glycerol and water are mixed and kneaded to obtain a kneaded material; The kneaded material is sequentially subjected to extrusion molding, drying and degumming to obtain a degummed green body; The debonded green body is subjected to sintering-coating treatment to obtain the recrystallized silicon carbide gas filtration membrane.

[0006] Preferably, the recrystallized silicon carbide gas filtration membrane is a single-channel tubular membrane or a multi-channel tubular membrane; the inner diameter of the single-channel tubular membrane is 15~25mm, the outer diameter is 30~40mm, and the length is 1000~1500mm; the inner diameter of each channel in the multi-channel tubular membrane is 2~25mm, and the length of the multi-channel tubular membrane is 1000~1500mm.

[0007] Preferably, the pH value of the gas to be treated is 0-14, the temperature is room temperature-800° C., and the volume content of impurities is ≤5%.

[0008] Preferably, the gas to be treated includes nitrogen and ammonia, the pH value of the gas to be treated is 11.5-12.5, the temperature is 50-60° C., and the volume content of impurities is 1-2.5%.

[0009] Preferably, the gas to be treated includes hydrogen chloride, the pH value of the gas to be treated is 3.5-4.5, the temperature is 300-350° C., and the volume content of impurities is 1-5%.

[0010] Preferably, the purification conditions include: the flow rate of the gas to be treated is ≤30 m / s, the pressure is ≤1 kPa, the ambient temperature is ≤50° C., and the relative humidity is ≤45%.

[0011] Preferably, the mass ratio of silicon carbide, cellulose, dextran, vegetable oil, glycerol and water is 70:8~10:3~5:5~7:1~3:8~10.

[0012] Preferably, the kneading treatment is carried out at a temperature of 15-35° C., for a time of 6-10 h, and at a rotation speed of 15-45 rpm; and the degumming treatment is carried out at a temperature of 115-125° C., for a time of 2-4 h.

[0013] Preferably, the sintering-coating process comprises sequentially performing sintering and coating processes, and the sintering-coating process is performed 3 to 4 times.

[0014] Preferably, the temperature of each sintering is independently 2400-2500° C., and the holding time of each sintering is independently 3-5 hours; The coating reagent used for each coating treatment includes silicon carbide, cellulose, dextran, vegetable oil, glycerol and water, and the mass ratio of silicon carbide, cellulose, dextran, vegetable oil, glycerol and water in the coating reagent is independently 70:8~10:3~5:5~7:1~3:8~10; each coating treatment is independently carried out under a pressure of 0.0005~0.0015MPa.

[0015] The present invention provides a gas purification method, comprising the following steps: using a recrystallized silicon carbide gas filter membrane to purify the gas to be treated to obtain purified gas; the preparation method of the recrystallized silicon carbide gas filter membrane comprises the following steps: mixing silicon carbide, cellulose, dextran, vegetable oil, glycerol and water, and kneading to obtain a kneaded material; sequentially extruding, drying and degumming the kneaded material to obtain a degummed blank; sintering-coating the degummed blank to obtain the recrystallized silicon carbide gas filter membrane. The present invention uses a recrystallized silicon carbide gas filter membrane to purify the gas to be treated, which is acid- and alkali-resistant and high-temperature-resistant, and is convenient for directly purifying corrosive high-temperature gas.

[0016] Furthermore, organic polymer gas filtration membranes have a high damage rate, a short service life, are prone to secondary pollution, and the quality of the purified gas is unstable. The recrystallized silicon carbide gas filtration membrane described in the present invention has a long service life, no secondary pollution, and the quality of the purified gas is stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart of recrystallizing a silicon carbide gas filtration membrane in an embodiment of the present invention; Figure 2 This is a physical picture of the recrystallized silicon carbide gas filtration membrane used in Application Example 1; Figure 3 This is a physical picture of the recrystallized silicon carbide gas filtration membrane used in Application Example 2. DETAILED DESCRIPTION

[0018] The present invention provides a gas purification method, comprising the following steps: The gas to be treated is purified by using a recrystallized silicon carbide gas filter membrane to obtain purified gas; The method for preparing the recrystallized silicon carbide gas filtration membrane comprises the following steps: Silicon carbide, cellulose, dextran, vegetable oil, glycerol and water are mixed and kneaded to obtain a kneaded material; The kneaded material is sequentially subjected to extrusion molding, drying and degumming to obtain a degummed green body; The debonded green body is subjected to sintering-coating treatment to obtain the recrystallized silicon carbide gas filtration membrane.

[0019] The present invention uses a recrystallized silicon carbide gas filter membrane to purify gas, which is acid-resistant, alkali-resistant and high-temperature-resistant, convenient for directly purifying corrosive high-temperature gas, and has excellent purification effect. The following first describes the recrystallized silicon carbide gas filter membrane of the present invention in detail.

[0020] As an embodiment of the present invention, the recrystallized silicon carbide gas filter membrane can be a single-channel tubular membrane or a multi-channel tubular membrane; the inner diameter of the single-channel tubular membrane can be 15~25mm, specifically 21mm; the outer diameter can be 30~40mm, specifically 35mm; the length can be 1000~1500mm, specifically 1200mm; the number of channels of the multi-channel tubular membrane can be customized according to customer requirements, for example, the number of channels of the multi-channel tubular membrane can be 19 holes, and the inner diameter of each channel can be 2~25mm, specifically 2mm, 4mm, 21mm or 25mm; the length of the multi-channel tubular membrane can be 1000~1500mm, specifically 1200mm; the specific size of the recrystallized silicon carbide gas filter membrane can be customized according to actual needs.

[0021] As an embodiment of the present invention, the method for preparing the recrystallized silicon carbide gas filtration membrane comprises the following steps: Silicon carbide, cellulose, dextran, vegetable oil, glycerol and water are mixed and kneaded to obtain a kneaded material; The kneaded material is sequentially subjected to extrusion molding, drying and degumming to obtain a degummed green body; The debonded green body is subjected to sintering-coating treatment to obtain the recrystallized silicon carbide gas filtration membrane.

[0022] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known to those skilled in the art or are prepared by methods well known to those skilled in the art.

[0023] The present invention mixes silicon carbide, cellulose, dextran, vegetable oil, glycerol and water, and performs kneading treatment to obtain a kneaded material. As an embodiment of the present invention, the mass ratio of silicon carbide, cellulose, dextran, vegetable oil, glycerol and water can be 70:8~10:3~5:5~7:1~3:8~10, specifically 70:9:6:2:9. In an embodiment of the present invention, the purity of silicon carbide is 99.8wt%, the particle size of silicon carbide is 0.7~1.2μm, wherein silicon carbide with a particle size of ≥1μm accounts for more than 50% of the total mass of silicon carbide; the glycerol is food-grade glycerol with a purity of 98%; the dextran is dextran XT300; and the water is purified water. In the present invention, silicon carbide is used as a matrix material to construct the main body of the gas filtration membrane. The use of silicon carbide with the above dosage and particle size is conducive to improving the strength of the gas filtration membrane and the membrane body throughput (i.e., membrane flux). In the present invention, glycerol and dextran are used as adhesives. The above-mentioned amount of glycerol and dextran are compounded and used to fill the gaps between silicon carbide particles, so that the silicon carbide particles are bonded together, ensuring that extrusion and subsequent processes proceed smoothly, and finally preparing a gas filtration membrane with excellent performance. In the present invention, cellulose can form a binding force to ensure that the membrane body will not loosen or crack. In the present invention, vegetable oil and water are used as dispersants, so that the raw materials can be dispersed and mixed evenly, which is convenient for preparing a gas filtration membrane with excellent uniformity.

[0024] As an embodiment of the present invention, the silicon carbide, cellulose, dextran, vegetable oil, glycerol and water can be mixed in the following manner: silicon carbide, cellulose and dextran are mixed, and the resulting mixture is mixed with water, vegetable oil and glycerol. As an embodiment of the present invention, the temperature of the kneading treatment can be 15-35°C, specifically 15°C, 20°C, 25°C, 30°C or 35°C; the time can be 6-10h, specifically 6h, 7h, 8h, 9h or 10h; the speed can be 15-45rpm, specifically 15rpm, 20rpm, 25rpm, 30rpm, 35rpm, 40rpm or 45rpm. In an embodiment of the present invention, the kneading treatment is specifically carried out in a kneader. In the embodiment of the present invention, mixing and kneading treatment under the above conditions are carried out, which is conducive to obtaining a kneading material with uniform texture and stable performance.

[0025] After obtaining the kneaded material, the present invention sequentially performs extrusion molding, drying and degumming on the kneaded material to obtain a degummed blank. The present invention performs extrusion molding according to the specific shape of the recrystallized silicon carbide gas filter membrane to obtain a blank; for example, when the recrystallized silicon carbide gas filter membrane is a single-channel tube-tube membrane, a single-channel tube-tube membrane blank is obtained by extrusion molding; the present invention does not specifically limit the operating conditions of the extrusion molding, and the conditions familiar to those skilled in the art can be used. In an embodiment of the present invention, the extrusion molding is specifically carried out in an extruder. The present invention adopts wet material extrusion molding, which has at least the following advantages: 1. Production continuity and high efficiency: wet material extrusion molding can achieve continuous production, greatly improving production efficiency; 2. Wide applicability: by replacing the mold, different types of filter membranes and customized membranes can be extruded; 3. Simple equipment and low investment: compared with injection molding machines and calenders, wet material extrusion molding has the advantages of simple equipment structure, low investment, convenient installation and debugging, small footprint, and low requirements for factory buildings and supporting facilities.

[0026] After obtaining the green body, the present invention dries the green body to obtain a dried green body. The present invention has no special limitation on the drying, as long as the moisture in the green body can be removed. In an embodiment of the present invention, the drying is specifically performed in an oven.

[0027] After obtaining the dried green body, the present invention degummes the dried green body to obtain a degummed green body. As an embodiment of the present invention, the degumming temperature can be 115-125°C, specifically 115°C, 118°C, 120°C, 122°C or 125°C; the time can be 2-4h, specifically 2h, 2.5h, 3h, 3.5h or 4h. In the embodiment of the present invention, degumming is carried out under the above conditions, which can effectively remove vegetable oil and glycerol, and finally prepare a gas filtration membrane with excellent performance.

[0028] After obtaining the degummed green body, the present invention performs a sintering-coating process on the degummed green body to obtain the recrystallized silicon carbide gas filtration membrane. As an embodiment of the present invention, the sintering-coating process includes sequentially performing sintering and coating processes, and the number of times of the sintering-coating process is 3 to 4 times.

[0029] As an embodiment of the present invention, the sintering temperature of each time can be independently 2400~2500℃, specifically 2410℃, 2420℃, 2430℃, 2440℃, 2450℃, 2460℃, 2470℃, 2480℃, 2490℃ or 2500℃; the holding time of each sintering can be independently 3~5h, specifically 3h, 3.5h, 4h, 4.5h or 5h. As an embodiment of the present invention, taking the sintering temperature of 2450°C as an example, the temperature raising procedure to the desired sintering temperature may be: uniformly raising the temperature from room temperature to 200°C over 30 minutes; uniformly raising the temperature from 200°C to 900°C over 60 minutes; uniformly raising the temperature from 900°C to 1100°C over 30 minutes; uniformly raising the temperature from 1100°C to 2000°C over 45 minutes; uniformly raising the temperature from 2000°C to 2410°C over 20 minutes; uniformly raising the temperature from 2410°C to 2450°C over 10 minutes. As an embodiment of the present invention, cooling is further included after each sintering, and the cooling may be specifically natural cooling, and the temperature after each cooling may specifically be room temperature.

[0030] As an embodiment of the present invention, the coating reagent used for each coating treatment may include silicon carbide, cellulose, dextran, vegetable oil, glycerol and water. The mass ratio of silicon carbide, cellulose, dextran, vegetable oil, glycerol and water in the coating reagent may be independently 70:8~10:3~5:5~7:1~3:8~10, specifically 70:9:6:2:9; each coating treatment may be independently carried out under a pressure of 0.0005~0.0015MPa, specifically 0.001MPa.

[0031] The present invention can cause silicon carbide to recrystallize through sintering, and a pore structure will be formed during the recrystallization process. The pore size can be reduced through coating treatment. In the embodiment of the present invention, sintering and coating treatment are carried out under the above conditions, so that the recrystallized silicon carbide gas filter membrane has a suitable pore size and porosity, which is beneficial to ensure a better purification effect on the gas while improving the purification efficiency.

[0032] After the sintering-coating process, the present invention preferably further comprises testing, and the finished product is qualified in the testing. As an embodiment of the present invention, the specific testing requirements are as follows: 1 General requirements and health and safety requirements 1.1 Components should be made of non-toxic, harmless and non-radioactive materials.

[0033] 1.3 Components should comply with the "Sanitary Safety Evaluation Standards for Drinking Water Transmission and Distribution Equipment and Protective Materials".

[0034] 2 Appearance quality The overall color of the component should be uniform, and there should be no cracks, pits, gaps or peeling when observed with the naked eye, and the cross-section should be flat.

[0035] 3 Dimension requirements 3.1 The allowable deviation of component diameter and flow channel inner diameter shall comply with the requirements of Table 1.

[0036] 3.2 The curvature of the components shall comply with the requirements of Table 2.

[0037] 3.3 The allowable tolerance of the actual channel diameter of the component shall not exceed 5% of the nominal channel diameter.

[0038] 3.4 The minimum length of the component is 200mm and the maximum length is 1500mm.

[0039] Table 1 Diameter tolerance

[0040] Table 2 Curvature

[0041] 4 Performance requirements 4.1 The pure water flux, overall bubbling pressure and membrane porosity of the element shall comply with the requirements of Table 3.

[0042] Table 3 Performance requirements

[0043] 4.2 The bending strength of components shall comply with the requirements of Table 4.

[0044] Table 4 Bending strength

[0045] 4.3 The acid and alkali corrosion resistance of the components shall comply with the requirements of Table 5.

[0046] Table 5 Acid and alkali corrosion resistance

[0047] 4.4 The component defect rate shall comply with the requirements of Table 6 (for all specifications of products).

[0048] Table 6 Defect rate

[0049] 4.5 The component aperture range shall comply with the requirements of Table 7.

[0050] Table 7 Aperture range

[0051] The recrystallized silicon carbide gas filtration membrane prepared by the method of the present invention has good thermal stability, and the operating temperature can be higher than 400°C, and even up to 800°C; it has good chemical stability, is resistant to acids and alkalis, and organic solvents, is suitable for a wider pH range, can be used in highly corrosive media, and can be cleaned with chemical reagents; it has high mechanical strength and can be used under higher pressures; it has strong antimicrobial ability, does not react with microorganisms, is non-toxic itself, and does not pollute the separated system, so it has unique advantages in the food and biochemical fields.

[0052] After the recrystallized silicon carbide gas filter membrane is obtained, the present invention uses the recrystallized silicon carbide gas filter membrane to purify the gas to be treated to obtain purified gas.

[0053] As an embodiment of the present invention, the pH value of the gas to be treated can be 0-14, further can be 4-12, specifically can be 4, 5, 6, 7, 8, 9, 10, 11 or 12, that is, the recrystallized silicon carbide gas filter membrane of the present invention can purify neutral gas, acidic gas, and alkaline gas. As an embodiment of the present invention, the temperature of the gas to be treated can be room temperature-800°C, further can be 30-650°C, further can be 50-350°C, specifically can be 50°C, 60°C, 80°C, 100°C, 150°C, 200°C, 250°C, 300°C or 350°C, that is, the recrystallized silicon carbide gas filter membrane of the present invention can purify room temperature gas, and can also purify high temperature gas. As an embodiment of the present invention, the volume content of impurities in the gas to be treated is ≤5%, further can be 1-5%, specifically can be 1%, 2%, 3%, 4% or 5%. As an embodiment of the present invention, the gas to be treated may be a single gas or a mixed gas, and may be treated according to actual needs.

[0054] As an embodiment of the present invention, the gas to be treated may include nitrogen and ammonia, the pH value of the gas to be treated may be 11.5~12.5 (specifically 12), the temperature may be 50~60°C, and the volume content of impurities may be 1~2.5%, specifically 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2% or 2.5%.

[0055] As an embodiment of the present invention, the pH value of the gas to be treated can be 3.5-4.5 (specifically 4), the temperature can be 300-350°C, and the volume content of impurities can be 1-5%, specifically 1%, 1.2%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%.

[0056] As an embodiment of the present invention, the purification conditions may include: the flow rate of the gas to be treated is ≤30m / s, and may further be 15~30m / s, and may specifically be 15m / s, 20m / s, 25m / s or 30m / s; the pressure is ≤1kPa, and may further be 0.45~1kPa, and may specifically be 0.45kPa, 0.6kPa, 0.8kPa or 1kPa; the ambient temperature is ≤50°C, and may further be 25~40°C, and may specifically be 25°C, 30°C, 35°C or 40°C; the relative humidity is ≤45%, and may further be 30~45%, and may specifically be 30%, 35%, 40% or 45%.

[0057] As an embodiment of the present invention, the volume content of impurities in the purified gas may be ≤0.5%, further may be 0.1-0.5%, specifically may be 0.1%, 0.2%, 0.3%, 0.4% or 0.5%.

[0058] The recrystallized silicon carbide gas filter membrane prepared by the method of the present invention has a suitable pore size and porosity. In addition to meeting the requirements of purification accuracy, pressure and flux, its operating temperature can be increased to 800°C, filling the shortcoming of other filter media that are not resistant to high temperatures. It can be used in acidic gas or alkaline gas purification without the risk of secondary contamination of other media. In view of the high hardness and corrosion resistance of recrystallized silicon carbide, the service life of the recrystallized silicon carbide gas filter membrane is greatly improved, the maintenance cycle is extended, and the operating cost is reduced.

[0059] Figure 1 The flowchart of the recrystallized silicon carbide gas filter membrane in the embodiment of the present invention is shown below. The technical scheme of the present invention will be clearly and completely described in combination with the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] The purity of silicon carbide used in the following experiments is 99.8%, the particle size of the silicon carbide is 0.7~1.2μm, of which silicon carbide with a particle size ≥1μm accounts for more than 50% of the total silicon carbide, and the silicon carbide powder comes from Shenyang Changxin New Materials Co., Ltd.; the glycerol used is food-grade glycerol with a purity of 98%; the dextran used is dextran XT300; and the water used is purified water.

[0061] Example 1 Silicon carbide, cellulose and dextran are mixed, and the obtained mixture, water, vegetable oil and glycerol are placed in a kneader, and kneaded for 6 hours at room temperature and a stirring speed of 30 rpm to obtain a kneaded material; wherein the mass ratio of silicon carbide, cellulose, dextran, vegetable oil, glycerol and water is 70:9:4:6:2:9; placing the kneaded material in an extruder for extrusion to obtain a single-channel tubular membrane body; Placing the single-channel tubular membrane body in an oven for drying to remove moisture, thereby obtaining a dried single-channel tubular membrane body; Placing the dried single-channel tubular membrane body in a degumming furnace, and performing degumming at 120° C. for 3 hours to remove vegetable oil and glycerol, thereby obtaining a degummed single-channel tubular membrane body; The degummed single-channel tubular membrane blank is placed in a vacuum induction sintering furnace, and the temperature is uniformly increased from room temperature to 200°C after 30 minutes, and the temperature is uniformly increased from 200°C to 900°C after 60 minutes, and the temperature is uniformly increased from 900°C to 1100°C after 30 minutes, and the temperature is uniformly increased from 1100°C to 2000°C after 45 minutes, and the temperature is uniformly increased from 2000°C to 2410°C after 20 minutes, and the temperature is uniformly increased from 2410°C to 2450°C after 10 minutes, and sintered at 2450°C for 4 hours, and then naturally cooled to room temperature to obtain a sintered single-channel tubular membrane blank; under a pressure of 0.001MPa, a coating machine is used to coat the inner wall of the sintered single-channel tubular membrane blank. A coating treatment is performed to obtain a coated single-channel tubular membrane blank; wherein the coating agent used for the coating treatment is a mixture of silicon carbide, cellulose, dextran, vegetable oil, glycerol and water in a mass ratio of 70:9:4:6:2:9; then the sintering-coating treatment process is repeated in sequence, and the sintering-coating treatment process is performed 3 times in total to obtain a recrystallized silicon carbide gas filtration membrane (specifically a single-channel tubular membrane), and then a bubble press and a flux machine are used for testing (refer to the aforementioned testing requirements 1 to 4 for testing, which will not be repeated here), and qualified products are placed in a finished product warehouse for storage; the recrystallized silicon carbide gas filtration membrane has a length of 80 mm, an inner diameter of 21 mm, and an outer diameter of 35 mm.

[0062] Example 2 A recrystallized silicon carbide gas filter membrane was prepared by referring to the method of Example 1, except that the size of the recrystallized silicon carbide gas filter membrane was different. In this example, the recrystallized silicon carbide gas filter membrane had a length of 1200 mm, an inner diameter of 21 mm, and an outer diameter of 35 mm.

[0063] Application Example 1 A recrystallized silicon carbide gas filtration membrane was prepared according to the method of Example 1. Figure 2 As shown, its length is 80mm, the inner diameter is 21mm, and the outer diameter is 35mm; the above-mentioned recrystallized silicon carbide gas filter membrane is used to purify the alkaline mixed gas to be treated of Wuhan Zhisheng Environmental Protection Technology Co., Ltd. to obtain a purified alkaline mixed gas; wherein the pH value of the alkaline mixed gas to be treated is 12, the temperature is 50~60℃, the main components are nitrogen and ammonia, and it also contains impurities such as dust, and the volume content of impurities is 2.5%; the purification conditions include: the flow rate of the alkaline mixed gas to be treated is 15m / s, the pressure is 0.45kPa, the ambient temperature is 25℃, and the relative humidity is 35%; the volume content of impurities in the purified alkaline mixed gas is 0.5%. It shows that the recrystallized silicon carbide gas filter membrane prepared by the present invention can achieve the purification of the alkaline mixed gas to be treated.

[0064] Application Example 2 A recrystallized silicon carbide gas filtration membrane was prepared according to the method of Example 2. Figure 3 As shown, its length is 1200mm, the inner diameter is 21mm, and the outer diameter is 35mm; the above-mentioned recrystallized silicon carbide gas filter membrane is used to purify the acid gas to be treated of Sichuan Star Energy Environmental Protection Technology Co., Ltd. to obtain purified acid gas; wherein the pH value of the acid gas to be treated is 4, the temperature is 300~350℃, the main component is hydrogen chloride, and it also contains impurities such as dust, and the volume content of impurities is 1%; the purification conditions include: the flow rate of the acid gas to be treated is 25m / s, the pressure is 1kPa, the ambient temperature is 40℃, and the relative humidity is 40%; the mass content of impurities in the purified acid gas is 0.3%. It shows that the recrystallized silicon carbide gas filter membrane prepared by the present invention can achieve the purification of the acid gas to be treated.

[0065] From the above results, it can be seen that the present invention uses a recrystallized silicon carbide gas filter membrane to purify the gas to be treated, which has stronger acid and alkali corrosion resistance and can be widely used for the purification of special gases such as acidic gases or alkaline gases. At the same time, the recrystallized silicon carbide gas filter membrane has high temperature resistance. When purifying high-temperature gases in special industries, there is no need to cool down in advance, and high-temperature treatment can be directly purified. In addition, the Mohs hardness of silicon carbide is as high as 9.2~9.5, second only to diamond. It is one of the very hard substances in nature. Its superior hardness can ensure a long service life on the basis of having a good purification effect, thereby reducing operating costs.

[0066] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A gas purification method, characterized in that: The following steps are involved: The gas to be treated is purified by using a recrystallized silicon carbide gas filter membrane to obtain purified gas; The method for preparing the recrystallized silicon carbide gas filtration membrane comprises the following steps: Silicon carbide, cellulose, dextran, vegetable oil, glycerol and water are mixed and kneaded to obtain a kneaded material; The kneaded material is sequentially subjected to extrusion molding, drying and degumming to obtain a degummed green body; The debonded green body is subjected to sintering-coating treatment to obtain the recrystallized silicon carbide gas filtration membrane.

2. The gas purification method according to claim 1, characterized in that: The recrystallized silicon carbide gas filtration membrane is a single-channel tubular membrane or a multi-channel tubular membrane; the inner diameter of the single-channel tubular membrane is 15-25 mm, the outer diameter is 30-40 mm, and the length is 1000-1500 mm; the inner diameter of each channel in the multi-channel tubular membrane is 2-25 mm, and the length of the multi-channel tubular membrane is 1000-1500 mm.

3. The gas purification method according to claim 1, characterized in that: The pH value of the gas to be treated is 0-14, the temperature is room temperature-800°C, and the volume content of impurities is ≤5%.

4. The gas purification method according to claim 3, characterized in that: The gas to be treated includes nitrogen and ammonia, the pH value of the gas to be treated is 11.5-12.5, the temperature is 50-60° C., and the volume content of impurities is 1-2.5%.

5. The gas purification method according to claim 3, characterized in that: The gas to be treated includes hydrogen chloride, the pH value of the gas to be treated is 3.5-4.5, the temperature is 300-350° C., and the volume content of impurities is 1-5%.

6. The gas purification method according to any one of claims 1 to 5, characterized in that: The purification conditions include: the flow rate of the gas to be treated is ≤30m / s, the pressure is ≤1kPa, the ambient temperature is ≤50°C, and the relative humidity is ≤45%.

7. The gas purification method according to claim 1, characterized in that: The mass ratio of silicon carbide, cellulose, dextran, vegetable oil, glycerol and water is 70:8-10:3-5:5-7:1-3:8-10.

8. The gas purification method according to claim 1 or 7, characterized in that: The kneading treatment is performed at a temperature of 15-35° C., a time of 6-10 hours, and a rotation speed of 15-45 rpm; the degumming treatment is performed at a temperature of 115-125° C., and a time of 2-4 hours.

9. The gas purification method according to claim 1, characterized in that: The sintering-film coating process includes sequentially performing sintering and film coating processes, and the number of times of the sintering-film coating process is 3 to 4 times.

10. The gas purification method according to claim 9, characterized in that: The temperature of each sintering is independently 2400-2500°C, and the holding time of each sintering is independently 3-5h; The coating reagent used for each coating treatment includes silicon carbide, cellulose, dextran, vegetable oil, glycerol and water, and the mass ratio of silicon carbide, cellulose, dextran, vegetable oil, glycerol and water in the coating reagent is independently 70:8~10:3~5:5~7:1~3:8~10; each coating treatment is independently carried out under a pressure of 0.0005~0.0015MPa.

Images