A high-temperature fiber filter tube and its preparation method

Abstract

The present invention relates to the field of chemical industry, and in particular to a high-temperature fiber filter tube and a preparation method thereof. The preparation method provided by the present invention is to chop high-temperature inorganic fibers through a chopping processing device to obtain chopped fibers of suitable length, 5 mm ≤ average fiber length ≤ 20 mm, and then slurry dispersed in water by a high-speed disperser, and then add additives, continue slurrying and dispersing, and finally add an inorganic binder for flocculation. The flocculated slurry is dehydrated and formed by vacuum filtration, and then dried. After drying, it is polished, and finally a specific mixed sol is applied to the surface of the filter tube so that the mixed sol is evenly distributed in the dry blank, and dried again to obtain a finished fiber filter tube. The obtained fiber filter tube has high porosity, small pressure difference, and good acid resistance, which is conducive to improving the use effect of the waste acid regeneration process.

Description

Technical Field

[0001] The present invention relates to the field of chemical industry, and in particular to a high-temperature fiber filter tube and a preparation method thereof. Background Art

[0002] High-temperature fiber filter tubes offer excellent heat resistance and dust filtration performance, making them the preferred material for high-temperature smoke and dust filtration in industries such as glass and cement. In recent years, refineries have been rapidly commissioning alkylation units to produce alkylate oil to meet the requirements of China VI gasoline upgrades. Most alkylation units utilize a sulfuric acid process, generating significant amounts of waste acid. Consequently, the construction of waste acid regeneration units is crucial for both waste acid disposal and fresh acid supply.

[0003] The waste acid regeneration process is to convert the sulfuric acid with a concentration of about 90% produced by the alkylation unit into sulfuric acid with a concentration of 98%~99.2% through incineration, decomposition, oxidation and absorption. This sulfuric acid can be returned to the alkylation unit for recycling as a catalyst.

[0004] There are two types of waste acid regeneration processes that are currently used more frequently: one is dry sulfuric acid (DuPont MECSSAR technology and domestic Nanning Institute of Chemical Technology), and the other is wet sulfuric acid (WSA technology of Denmark's Topsoe and SOP technology of Austria's P&P). The comparison of the two processes is shown in Table 1 below. It can be seen that the wet sulfuric acid regeneration process has many advantages and has therefore become a more popular waste acid regeneration process. Among them, the SOP sulfuric acid recovery process of Austria's P&P is as follows. Figure 1 shown.

[0005] Table 1: Comparison of two spent acid regeneration processes

[0006]

[0007] Although traditional high-temperature fiber filter tubes are also made from high-purity spun aluminum silicate fiber, high-purity blown aluminum silicate fiber, and soluble ceramic fiber, with inorganic binders and additives, these high-temperature fiber filter tubes produced using traditional raw materials, formulations, and processes have low porosity, large pressure differentials, and are not resistant to acid gas corrosion. They are primarily used as high-temperature smoke filter materials in industries like glass and cement, but are not suitable for SO2 flue gas filtration in waste acid regeneration units (SAR) in the petrochemical industry. In other words, these conventional filter tubes are only suitable for applications with low sulfur content in flue gas and low chemical corrosion resistance requirements, and are not suitable for waste acid regeneration units (SAR) containing high-concentration SO2 flue gas (SO2 concentration ≥10%).

[0008] As the country increases its efforts in energy conservation, consumption reduction, safety and environmental protection in various industries, the market demand for high-temperature fiber filter tubes for waste acid regeneration (SAR) devices is gradually increasing. Such high-temperature fiber filter tubes for waste acid regeneration (SAR) devices must have high porosity, small pressure difference, and high filtration accuracy. The recovered sulfuric acid can be recycled as a catalyst and must be able to meet the SOP sulfuric acid recovery process conditions of the Austrian P&P company. Summary of the Invention

[0009] In view of this, the present invention provides a high-temperature fiber filter tube and a preparation method thereof. The high-temperature fiber filter tube prepared by the present invention has high porosity, small pressure difference and good acid resistance.

[0010] The present invention provides a method for preparing a high-temperature fiber filter tube, comprising the following steps:

[0011] A) chopping the high-temperature inorganic fibers to obtain chopped cotton;

[0012] The size specifications of the short-cut processed cotton are as follows: 5mm≤average fiber length≤20mm;

[0013] B) mixing the chopped cotton with water and beating the mixture, adding an additive to modify the mixture, and then adding an inorganic binder to flocculate the mixture to obtain a slurry;

[0014] C) dehydrating, shaping, and drying the slurry obtained in step B) to obtain a fiber filter tube;

[0015] D) contacting the fiber filter tube obtained in step C) with the mixed sol to allow the fiber filter tube to absorb the sol, allowing the fiber filter tube to stand for gelation, and drying to obtain a high-temperature fiber filter tube;

[0016] The mixed sol comprises the following components:

[0017] 30 parts by weight of alkaline sodium silicate;

[0018] 30 parts by weight of nitric acid-stabilized aluminum sol;

[0019] 40 parts by weight of water;

[0020] 0.1-0.4 parts by weight of delayed-release gelling admixture;

[0021] Wherein, the delayed-acting gelling admixture is at least one of calcium nitrate, calcium chloride and calcium acetate.

[0022] Preferably, in step A), the high-temperature inorganic fiber is high-purity spun aluminum silicate fiber and / or high-purity blown aluminum silicate fiber.

[0023] Preferably, in step B), the additive is cationic modified starch.

[0024] Preferably, in step B), the inorganic binder is silica sol or alumina sol.

[0025] Preferably, in step B), the amount of each material is as follows:

[0026] 60-90 parts by weight of chopped cotton;

[0027] 2 to 6 parts by weight of additives;

[0028] 5-20 parts by weight of inorganic binder

[0029] Preferably, in step D), the mixed sol comprises:

[0030] The alkaline sodium silica sol is an alkaline sodium silica sol with a solid content of 30%;

[0031] The nitric acid-stabilized aluminum sol is a nitric acid-stabilized aluminum sol with a solid content of 20%.

[0032] Preferably, step C) specifically comprises: placing the slurry obtained in step B) into a filter tube forming tank, placing a filter tube forming mold into the forming tank, dehydrating and forming by vacuum filtration, then demoulding, standing, and drying to obtain a fiber filter tube.

[0033] Preferably, in step C):

[0034] The vacuum degree of the vacuum filtration dehydration molding is 0.03-0.05 MPa, and the vacuum filtration time is 5-10 seconds;

[0035] The standing time is 10 to 20 minutes;

[0036] The drying temperature is 180-220° C. and the drying time is 2-3 hours.

[0037] Preferably, in step D):

[0038] The fiber filter tube obtained in step C) is contacted with the mixed sol by immersing the fiber filter tube obtained in step C) in the mixed sol;

[0039] The soaking time is 10 to 120 seconds;

[0040] After the glue is sucked, the weight of the fiber filter tube increases by 10% to 60%;

[0041] The standing time is 10 to 60 minutes;

[0042] The drying temperature is 180-220° C. and the drying time is 0.5-1 h.

[0043] The present invention also provides a high-temperature fiber filter tube, which is prepared by the preparation method described in the above technical solution.

[0044] The preparation method provided by the present invention involves chopping high-temperature inorganic fibers using a chopping processing device to obtain chopped fibers of an appropriate length, with an average fiber length of 5 mm or less and 20 mm or less. The fibers are then slurried and dispersed in water using a high-speed disperser, and additives are added. The slurry is further slurried and dispersed, and finally an inorganic binder is added for flocculation. The flocculated slurry is dehydrated and formed by vacuum filtration, and then dried. After drying, the fibers are polished, and finally, a specific mixed sol is applied to the surface of a filter tube to uniformly distribute the mixed sol within the dried blank. The finished product is then dried again to obtain the finished product. The resulting fiber filter tube has a high porosity, a low pressure difference, high filtration accuracy, and good acid resistance, which is beneficial for improving the filtration effect of the waste acid regeneration process.

[0045] The test results show that the high temperature fiber filter tube prepared by the present invention has a volume density of 300±20kg / m 3 , porosity ≥ 85%, pressure difference ≤ 0.55KPa, weight loss rate after immersion in 98% sulfuric acid ≤ 0.2%. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0047] Figure 1 Schematic diagram of the SOP sulfuric acid recovery process of P&P, Austria. DETAILED DESCRIPTION

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0049] In this article, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0050] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0051] As used herein, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Furthermore, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0052] In this document, when referring to a data range, if the unit is followed only by the right endpoint, it means that the units of the left and right endpoints are the same. For example, 800~1200r / min means that the units of the left endpoint "800" and the right endpoint "1200" are both r / min.

[0053] A method for preparing a high-temperature fiber filter tube comprises the following steps:

[0054] A) chopping the high-temperature inorganic fibers to obtain chopped cotton;

[0055] The size specifications of the short-cut processed cotton are as follows: 5mm≤average fiber length≤20mm;

[0056] B) mixing the chopped cotton with water and beating the mixture, adding an additive to modify the mixture, and then adding an inorganic binder to flocculate the mixture to obtain a slurry;

[0057] C) dehydrating, shaping, and drying the slurry obtained in step B) to obtain a fiber filter tube;

[0058] D) contacting the fiber filter tube obtained in step C) with the mixed sol to allow the fiber filter tube to absorb the sol, allowing the fiber filter tube to stand for gelation, and drying to obtain a high-temperature fiber filter tube;

[0059] The mixed sol comprises the following components:

[0060] 30 parts by weight of alkaline sodium silicate;

[0061] 30 parts by weight of nitric acid-stabilized aluminum sol;

[0062] 40 parts by weight of water;

[0063] 0.1-0.4 parts by weight of delayed-release gelling admixture;

[0064] Wherein, the delayed-acting gelling admixture is at least one of calcium nitrate, calcium chloride and calcium acetate.

[0065] [About Step A]:

[0066] A) High temperature inorganic fibers are chopped to obtain chopped cotton.

[0067] In the present invention, the high-temperature inorganic fiber refers to an inorganic fiber that is resistant to high temperatures, specifically an inorganic fiber that is resistant to high temperatures ≥800°C.

[0068] In the present invention, the high-temperature inorganic fiber is preferably high-purity spun aluminum silicate fiber and / or high-purity blown aluminum silicate fiber. Aluminum silicate fibers can be classified into high-purity and high-aluminum types. The compositional specifications of high-purity and high-aluminum aluminum silicate fibers are shown in Table 2. Spun and blown are two manufacturing processes for producing ceramic fibers. Fibers produced by these two processes are referred to as spun fibers and blown fibers, respectively.

[0069] Table 2: Classification of aluminum silicate fibers

[0070]

[0071] In the present invention, the high-temperature inorganic fibers are chopped, specifically by chopped processing equipment. In the present invention, the goal of the chopped processing is to obtain fibers with an average fiber length of 5mm≤≤20mm, specifically 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm. Specifically, the high-temperature inorganic fibers are placed in the chopped processing equipment, and the cotton balls with a particle size greater than 20mm are first removed through a 20mm sieve hole, and then the short fibers and slag balls with a particle size less than 5mm are removed through a 5mm sieve hole, thereby obtaining fibers of appropriate length with an average fiber length of 5mm≤20mm. In the present invention, the rotation speed of the short-cutting equipment is preferably 800-1200 r / min, specifically 800 r / min, 900 r / min, 1000 r / min, 1100 r / min, and 1200 r / min. The short-cutting equipment is continuously fed and discharged to obtain fibers of target size.

[0072] In the present invention, when the high-temperature inorganic fibers are a combination of high-purity spun aluminum silicate fibers and high-purity blown aluminum silicate fibers, it is preferred to chop the two fibers separately during the chopped processing to obtain two types of chopped fiber cotton of target size, which are then put into subsequent use.

[0073] In the present invention, when the high-temperature inorganic fiber is a combination of high-purity spun aluminum silicate fiber and high-purity blown aluminum silicate fiber, the mass ratio of the high-purity spun aluminum silicate fiber to the high-purity blown aluminum silicate fiber is preferably (1~5):1, specifically 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1.

[0074] [About Step B]:

[0075] B) The chopped cotton and water are mixed and beaten, and then an additive is added to modify the cotton, and then an inorganic binder is added to flocculate the cotton to obtain a pulp.

[0076] In the present invention, the mass ratio of the chopped cotton to water is preferably 70:(4500-7000), specifically 70:4500, 70:5000, 70:5500, 70:6000, 70:6500, or 70:7000.

[0077] In the present invention, the chopped cotton and water are mixed and beaten, specifically, the chopped cotton and water are placed in a high-speed disperser for mixing and beating; the rotation speed of the high-speed disperser is preferably 600~800r / min, specifically 600r / min, 650r / min, 700r / min, 750r / min, 800r / min; the processing time of the high-speed disperser is preferably 30~45s, specifically 30s, 35s, 40s, 45s.

[0078] In the present invention, after the above-mentioned mixing and beating, an additive is added for modification. The additive is a non-inorganic binder additive, specifically a modifier. In the present invention, the additive is preferably a cationic modified starch, which has a dispersing and modifying effect on high-temperature inorganic fibers. In the present invention, the cationic modified starch is preferably CAS-2 starch, which is derived from Foshan Nanhai Huahao Huafeng Starch Co., Ltd. In the present invention, after adding the additive, it is preferably continued to stir at high speed for 60 to 90 seconds, specifically 60 seconds, 65 seconds, 70 seconds, 75 seconds, 80 seconds, 85 seconds, 90 seconds. Wherein, the rotation speed of the high-speed stirring is preferably 600 to 800 r / min, specifically 600 r / min, 650 r / min, 700 r / min, 750 r / min, 800 r / min, and more preferably the same as the rotation speed set during the previous mixing and beating step.

[0079] In the present invention, after the above treatment, an inorganic binder is added for flocculation. The inorganic binder is preferably silica sol or alumina sol. The silica sol is preferably alkaline sodium silica sol, more preferably alkaline sodium silica sol with a solid content of 30%. The alumina sol is preferably nitric acid-stabilized alumina sol, more preferably nitric acid-stabilized alumina sol with a solid content of 20%. The present invention does not particularly limit the source of the inorganic binder; any commercially available product is sufficient. In the present invention, stirring and flocculation are performed after the addition of the inorganic binder. The stirring speed is preferably 100-200 r / min, specifically 100 r / min, 150 r / min, or 200 r / min. Specifically, after the additive modification step, the speed of the high-speed disperser is reduced to the above speed, and the inorganic binder is continued to be added to the system for stirring and flocculation. The stirring time is preferably 60-80 s, specifically 60 s, 65 s, 70 s, 75 s, or 80 s, until the slurry flocculates.

[0080] In the present invention, in step B), the amount of each material is preferably as follows:

[0081] 60-90 parts by weight of chopped cotton;

[0082] 2 to 6 parts by weight of additives;

[0083] 5-20 parts by weight of inorganic binder

[0084] The amount of the chopped cotton can be 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, or 90 parts. The amount of the additive can be 2 parts, 3 parts, 4 parts, 5 parts, or 6 parts. The amount of the inorganic binder can be 5 parts, 10 parts, 15 parts, or 20 parts.

[0085] [About Step C]:

[0086] C) Dehydrating and shaping the slurry obtained in step B), and drying the slurry to obtain a fiber filter tube.

[0087] In the present invention, step C) preferably specifically comprises: placing the slurry obtained in step B) into a filter tube forming tank, placing the filter tube forming mold into the forming tank, dehydrating and forming by vacuum filtration, then demoulding, standing, and drying to obtain a fiber filter tube.

[0088] The vacuum filtration dehydration molding is specifically performed by a Roots vacuum pump. The vacuum degree of the vacuum filtration dehydration molding is preferably 0.03-0.05 MPa, specifically 0.03 MPa, 0.04 MPa, or 0.05 MPa. The vacuum filtration time is preferably 5-10 seconds, specifically 5 seconds, 6 seconds, 7 seconds, 8 seconds, 9 seconds, or 10 seconds. After dehydration, demoulding is performed and the mold is allowed to stand after demoulding. The standing time is preferably 10-20 minutes, specifically 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes, or 20 minutes. After the above-mentioned standing time, drying is performed. The drying can specifically be carried out by sending the mold to a drying chamber for drying. The drying temperature is preferably 180-220° C., specifically 180° C., 185° C., 190° C., 195° C., 200° C., 205° C., 210° C., 215° C., or 220° C. The drying time is preferably 2-3 hours, specifically 2 hours, 2.5 hours, or 3 hours.

[0089] In the present invention, after drying, preferably polishing is further performed; specifically, the dried fiber filter tube is polished with a polishing device to make its surface smooth, and polished until the outer dimensions meet the requirements, thereby obtaining the fiber filter tube.

[0090] [About Step D]:

[0091] D) contacting the fiber filter tube obtained in step C) with the mixed sol to allow the fiber filter tube to absorb the sol, allowing the fiber filter tube to stand for gelation, and drying to obtain a high-temperature fiber filter tube.

[0092] In the present invention, the mixed sol comprises the following components:

[0093] 30 parts by weight of alkaline sodium silicate;

[0094] 30 parts by weight of nitric acid-stabilized aluminum sol;

[0095] 40 parts by weight of water;

[0096] 0.1~0.4 parts by weight of delayed-acting gelling admixture

[0097] The alkaline sodium silica sol is preferably an alkaline sodium silica sol having a solid content of 30%, and its source is not particularly limited, and it can be a commercial product. The nitric acid-stabilized aluminum sol is preferably a nitric acid-stabilized aluminum sol having a solid content of 20%, and its source is not particularly limited, and it can be a commercial product.

[0098] The delayed-acting gelling admixture is preferably at least one of calcium nitrate, calcium chloride and calcium acetate. The delayed-acting gelling admixture can be industrial grade or analytical grade; its function is to adjust the gelling time of the mixed sol, avoid the occurrence of gel during operation, and prevent the impregnated mixed sol from migrating during the drying process, which helps to reduce the pressure difference of the high-temperature fiber filter tube. The dosage of the delayed-acting gelling admixture can be specifically 0.1 parts, 0.2 parts, 0.3 parts, and 0.4 parts. The present invention can adjust the gelling speed and penetration of the inorganic glue through the above-mentioned mixed sol formula, and first generate gel and then dry it for the second time to avoid excessive migration of the inorganic glue to the surface of the filter tube, thereby reducing the 98% sulfuric acid immersion weight loss rate of the high-temperature fiber filter tube and improving its resistance to SO2 acid gas corrosion.

[0099] In the present invention, the fiber filter tube obtained in step C) is preferably contacted with the mixed sol by immersing the fiber filter tube in the mixed sol. This immersion allows the fiber filter tube to absorb the sol, resulting in a uniform distribution of the mixed sol within the dry fiber filter tube. The immersion time is preferably 10 to 120 seconds, specifically 10 seconds, 15 seconds, 20 seconds, 25 seconds, 30 seconds, 35 seconds, 40 seconds, 45 seconds, 50 seconds, 60 seconds, 65 seconds, 70 seconds, 75 seconds, 80 seconds, 85 seconds, 90 seconds, 95 seconds, 100 seconds, 110 seconds, or 120 seconds. After immersion, the filter tube is removed. In the present invention, the weight gain of the fiber filter tube after absorbing the sol is preferably controlled to be 10% to 60%, specifically 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, or 60%. After absorbing the sol, the mixed sol is allowed to stand for a certain period of time to allow the absorbed sol to completely gel. The standing time is preferably 10 to 60 minutes, specifically 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60 minutes. In the present invention, the temperature for the above operations (including soaking and standing) is not particularly limited and can be performed at room temperature, specifically 5 to 40°C. After standing, the mixed sol is dried. This drying can be performed in a drying chamber. The drying temperature is preferably 180 to 220°C, specifically 180, 185, 190, 195, 200, 205, 210, 215, or 220°C. The drying time is preferably 0.5 to 1 hour, specifically 0.5 or 1 hour. After drying, the finished high-temperature fiber filter tube is obtained.

[0100] The present invention also provides a high-temperature fiber filter tube prepared by the preparation method described in the above technical solution. The high-temperature fiber filter tube prepared by the present invention has a volume density of 300±20kg / m 3, porosity ≥ 85%, differential pressure ≤ 0.55 kPa, and weight loss ≤ 0.2% after immersion in 98% sulfuric acid. Existing technology cannot produce fiber filter tubes that meet these specifications. The high-temperature fiber filter tubes obtained in this invention are suitable for use in spent acid regeneration units (SARs) in the petrochemical industry and meet the SOP sulfuric acid recovery process requirements of P&P Austria.

[0101] The present invention also provides a waste acid regeneration process, wherein the fiber filter tube is the high-temperature fiber filter tube described in the above technical solution.

[0102] The preparation method provided by the present invention is to chop high-temperature inorganic fibers by short-cut processing equipment to obtain chopped fibers of suitable length of 5mm≤fiber average length≤20mm, and then disperse them in water by beating with a high-speed disperser, add additives, continue beating and dispersing, and finally add an inorganic binder for flocculation. The slurry after flocculation is dehydrated and formed by vacuum filtration, and then dried. After drying, polishing is performed, and finally a specific mixed sol is applied to the filter tube surface so that the mixed sol is evenly distributed in the dry blank, and the finished product is obtained after drying again. The porosity of the obtained fiber filter tube is high, the pressure difference is small, the filtration accuracy is high, and the acid resistance is good, which is conducive to improving the filtration effect of the waste acid regeneration process. The high-temperature fiber filter tube of the present invention is mainly suitable for the SAR waste acid regeneration device of the petrochemical industry and can meet the SOP sulfuric acid recovery process conditions of Austrian P&P company.

[0103] The test results show that the high temperature fiber filter tube prepared by the present invention has a volume density of 300±20kg / m 3 , porosity ≥ 85%, pressure difference ≤ 0.55KPa, weight loss rate after immersion in 98% sulfuric acid ≤ 0.2%.

[0104] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0105] In the following examples, the cationic modified starch was CAS-2 starch from Foshan Nanhai Huahao Huafeng Starch Co., Ltd. The nitric acid-stabilized aluminum sol was CY-L10A, a translucent colloid with a solids content of 20%, a pH of 3-5, and a particle size of 10 nm, sourced from Hangzhou Jiupeng New Materials Co., Ltd. The alkaline sodium silicate sol was JN-30, a translucent colloid with a solids content of 30%, a pH of 9-10, and a particle size of 12 nm, sourced from Linyi Kehan ​​Silicon Products Co., Ltd.

[0106] Example 1

[0107] A) High-purity spun aluminum silicate fibers were chopped using a chopped fiber processing machine to obtain high-purity spun chopped short-strand cotton with an average fiber length of 10 mm. High-purity blown aluminum silicate fibers were chopped using a chopped fiber processing machine to obtain high-purity blown short-strand cotton with an average fiber length of 8 mm.

[0108] B) Place high-purity spun chopped cotton, high-purity blown chopped cotton, and water in a high-speed disperser for slurry dispersion at 600 r / min for 45 seconds. Then, add the cationic modified starch additive and continue stirring at the same speed for 80 seconds. Then, adjust the disperser speed to 150 r / min, add the inorganic binder (alkaline sodium silicate sol with a solid content of 30%), and stir for 20 seconds until the slurry flocculates.

[0109] The amount of each material is as follows:

[0110] 50kg of high-purity spun short-cut cotton;

[0111] 20kg of high-purity chopped cotton;

[0112] 5kg additives;

[0113] 10kg of inorganic binder.

[0114] The ratio of the total amount of the chopped cotton to water is 70:6000.

[0115] C) The slurry obtained in step B) is placed in a filter tube forming tank. The filter tube forming mold is placed in the forming tank and vacuum filtered and dehydrated using a Roots vacuum pump at a vacuum of 0.04 MPa for 10 seconds. The mold is removed and allowed to stand for 10 minutes before being dried in a drying room at 220°C for 2 hours. The dried fiber filter tube is then polished using a grinding machine to achieve a smooth surface and meet the required dimensions.

[0116] D) The fiber filter tube obtained in step C) is completely immersed in the mixed sol for 10 seconds, then removed. The filter tube increases in weight by 30% after absorbing the sol. The tube is allowed to stand for 60 minutes until the mixed sol is completely gelled. The tube is then dried in a drying chamber at 220°C for 1 hour to obtain the finished high-temperature fiber filter tube.

[0117] The mixed sol is composed of: 30 kg of alkaline sodium silicate sol with a solid content of 30%; 30 kg of nitric acid-stabilized aluminum sol with a solid content of 20%, 40 kg of water, and 0.1 kg of calcium nitrate, a delayed-acting gelling agent admixture.

[0118] Example 2

[0119] A) High-purity spun aluminum silicate fibers were chopped using a chopped fiber processing machine to obtain high-purity spun chopped short-strand cotton with an average fiber length of 12 mm. High-purity blown aluminum silicate fibers were chopped using a chopped fiber processing machine to obtain high-purity blown short-strand cotton with an average fiber length of 6 mm.

[0120] B) Place high-purity spun chopped cotton, high-purity blown chopped cotton, and water in a high-speed disperser for slurry dispersion at 600 r / min for 45 seconds. Then, add the cationic modified starch additive and continue stirring at the same speed for 80 seconds. Then, adjust the disperser speed to 150 r / min, add the inorganic binder (20% solids content nitric acid stabilized aluminum sol), and stir for 20 seconds until the slurry flocculates.

[0121] The amount of each material is as follows:

[0122] 50kg of high-purity spun short-cut cotton;

[0123] 20kg of high-purity chopped cotton;

[0124] 5kg additives;

[0125] 20kg of inorganic binder.

[0126] The ratio of the total amount of the chopped cotton to water is 70:7000.

[0127] C) The slurry obtained in step B) is placed in a filter tube forming tank. The filter tube forming mold is placed in the forming tank and vacuum filtered and dehydrated using a Roots vacuum pump at a vacuum of 0.04 MPa for 10 seconds. The mold is removed and allowed to stand for 10 minutes before being dried in a drying room at 220°C for 2 hours. The dried fiber filter tube is then polished using a grinding machine to achieve a smooth surface and meet the required dimensions.

[0128] D) The fiber filter tube obtained in step C) is completely immersed in the mixed sol for 10 seconds, then removed. The filter tube increases in weight by 15% after absorbing the sol. The tube is allowed to stand for 20 minutes until the mixed sol is completely gelled. The tube is then dried in a drying chamber at 220°C for 1 hour to obtain the finished high-temperature fiber filter tube.

[0129] The mixed sol is composed of: 30 kg of alkaline sodium silicate sol with a solid content of 30%; 30 kg of nitric acid-stabilized aluminum sol with a solid content of 20%, 40 kg of water, and 0.4 kg of calcium chloride as a delayed-acting gelling agent admixture.

[0130] Example 3

[0131] A) High-purity blown aluminum silicate fibers are chopped by a chopped processing device to obtain high-purity blown chopped fibers with an average fiber length of 9 mm.

[0132] B) Place high-purity chopped strands and water in a high-speed disperser for slurrying and dispersion at 600 rpm for 45 seconds. Add the cationic modified starch additive and continue stirring at the same speed for 80 seconds. Then, adjust the disperser speed to 150 rpm, add the inorganic binder (20% solids content, nitric acid-stabilized aluminum sol), and stir for 20 seconds until the slurry flocculates.

[0133] The amount of each material is as follows:

[0134] 70kg of high-purity blown short-cut cotton;

[0135] 5kg additives;

[0136] 20kg of inorganic binder.

[0137] The ratio of the total amount of chopped cotton to water is 70:6500.

[0138] C) The slurry obtained in step B) is placed in a filter tube forming tank. The filter tube forming mold is placed in the forming tank and vacuum filtered and dehydrated using a Roots vacuum pump at a vacuum of 0.04 MPa for 10 seconds. The mold is removed and allowed to stand for 10 minutes before being dried in a drying room at 220°C for 2 hours. The dried fiber filter tube is then polished using a grinding machine to achieve a smooth surface and meet the required dimensions.

[0139] D) The fiber filter tube obtained in step C) is completely immersed in the mixed sol for 10 seconds, then removed. The filter tube increases in weight by 20% after absorbing the sol. The tube is allowed to stand for 20 minutes until the mixed sol is completely gelled. The tube is then dried in a drying chamber at 220°C for 1 hour to obtain the finished high-temperature fiber filter tube.

[0140] The mixed sol is composed of: 30 kg of alkaline sodium silicate sol with a solid content of 30%; 30 kg of nitric acid-stabilized aluminum sol with a solid content of 20%, 40 kg of water, and 0.4 kg of calcium chloride as a delayed-acting gelling agent admixture.

[0141] Comparative Example 1

[0142] Implement according to Example 1, except that:

[0143] In step A), the high-purity spun aluminum silicate fibers are processed into high-purity spun short-cut cotton with an average fiber length of 4 mm; and the high-purity blown aluminum silicate fibers are processed into high-purity blown short-cut cotton with an average fiber length of 3 mm.

[0144] In step D), the mixed sol used is composed of: 60 kg of alkaline sodium silicate sol with a solid content of 30%; and 40 kg of water.

[0145] Comparative Example 2

[0146] Implement according to Example 1, except that:

[0147] In step A), the high-purity spun aluminum silicate fibers are processed into high-purity spun short-cut cotton with an average fiber length of 28 mm; and the high-purity blown aluminum silicate fibers are processed into high-purity blown short-cut cotton with an average fiber length of 22 mm.

[0148] In step D), the mixed sol used is composed of: 60 kg of alkaline sodium silicate sol with a solid content of 30%; and 40 kg of water.

[0149] Product Testing :

[0150] The following tests were performed on the products obtained in each embodiment and comparative example, and the results are shown in Table 3.

[0151] (1) Bulk density: refer to GB / T 17911.

[0152] (2) Porosity: refer to GB / T 2997.

[0153] (3) Pressure difference: Connect the open end of the filter tube to the air inlet of the negative pressure equipment and seal it. Start the negative pressure equipment and adjust the valve opening to make the wind speed reach 5 m / s. After the wind speed stabilizes, read the display value on the equipment, which is the sample pressure difference value.

[0154] (4) Weight loss rate after immersion in 98% sulfuric acid: Take about 50g of filter tube (weight is recorded as W1) and immerse it in 1000g of 98% sulfuric acid. After immersion for 24 hours, take out the sample and dry it at 120℃ for 24 hours. The weight is recorded as W2. The weight loss rate is 100×(W1-W2) / W1.

[0155] Table 3: Test results

[0156]

[0157] It can be seen from the test results in the above table that the volume density of the high-temperature fiber filter tube obtained by the present invention is 300±60kg / m 3 , porosity ≥ 85%, differential pressure < 0.55KPa, 98% sulfuric acid immersion weight loss rate < 0.2%, good acid resistance, improving its resistance to SO2 acid gas corrosion. The fiber filter tube obtained in the comparative example has a porosity of less than 84%, a differential pressure greater than 0.7KPa, and a 98% sulfuric acid weight loss rate higher than 0.4%, indicating poor overall performance.

[0158] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal description of the claims, or if they include equivalent structural elements that are not substantially different from the literal description of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for preparing a high-temperature fiber filter tube, characterized in that: The following steps are involved: A) chopping the high-temperature inorganic fibers to obtain chopped cotton; The size specifications of the short-cut processed cotton are as follows: 5mm≤average fiber length≤20mm; B) mixing the chopped cotton and water to form a pulp, adding an additive to modify the cotton, and then adding an inorganic binder to form a flocculation to obtain a pulp; C) dehydrating, shaping, and drying the slurry obtained in step B) to obtain a fiber filter tube; D) contacting the fiber filter tube obtained in step C) with the mixed sol to allow the fiber filter tube to absorb the sol, allowing the fiber filter tube to stand for gelation, and drying to obtain a high-temperature fiber filter tube; in, The mixed sol comprises the following components: 30 parts by weight of alkaline sodium silicate; 30 parts by weight of nitric acid-stabilized aluminum sol; 40 parts by weight of water; 0.1-0.4 parts by weight of delayed-release gelling admixture; Wherein, the delayed-acting gelling admixture is at least one of calcium nitrate, calcium chloride and calcium acetate.

2. The preparation method according to claim 1, characterized in that In step A), the high-temperature inorganic fiber is high-purity spun aluminum silicate fiber and / or high-purity blown aluminum silicate fiber.

3. The preparation method according to claim 1, characterized in that In step B), the additive is cationic modified starch.

4. The preparation method according to claim 1, characterized in that In step B), the inorganic binder is silica sol or aluminum sol.

5. The preparation method according to claim 1, characterized in that In step B), the amount of each material is as follows: 60-90 parts by weight of chopped cotton; 2 to 6 parts by weight of additives; 5-20 parts by weight of inorganic binder 6. The preparation method according to claim 1, characterized in that In step D), the mixed sol comprises: The alkaline sodium silica sol is an alkaline sodium silica sol with a solid content of 30%; The nitric acid-stabilized aluminum sol is a nitric acid-stabilized aluminum sol with a solid content of 20%.

7. The preparation method according to claim 1, characterized in that Step C) specifically comprises: placing the slurry obtained in step B) into a filter tube forming tank, placing a filter tube forming mold into the forming tank, dehydrating and forming by vacuum filtration, then demoulding, standing, and drying to obtain a fiber filter tube.

8. The preparation method according to claim 7, characterized in that In step C): The vacuum degree of the vacuum filtration dehydration molding is 0.03-0.05 MPa, and the vacuum filtration time is 5-10 seconds; The standing time is 10 to 20 minutes; The drying temperature is 180-220° C. and the drying time is 2-3 hours.

9. The preparation method according to claim 1, characterized in that In step D): The fiber filter tube obtained in step C) is contacted with the mixed sol by immersing the fiber filter tube obtained in step C) in the mixed sol; The soaking time is 10 to 120 seconds; After the glue is sucked, the weight of the fiber filter tube increases by 10% to 60%; The standing time is 10 to 60 minutes; The drying temperature is 180-220° C. and the drying time is 0.5-1 h.

10. A high-temperature fiber filter tube, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9.

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