Dedusting agent, preparation method thereof, method for dedusting raw material gas for sulfuric acid synthesis and method for preparing sulfuric acid by wet method

Abstract

The invention discloses a dedusting agent and a preparation method thereof as well as a method for dedusting raw material gas for sulfuric acid synthesis and a method for preparing sulfuric acid by a wet process, the dedusting agent comprises an adsorbent and a carrier, and the adsorbent is at least one of heat-resistant fiber and sodium silicate. The dedusting agent disclosed by the invention can be used for adsorbing and trapping fine-grained dust within a range of 20-100nm. After the dedusting agent is used, the content of Fe at an outlet of the dedusting agent can be ensured to be within 50ppb.

Description

Technical Field

[0001] The invention relates to a purifier used in a sulfuric acid process, and in particular to a dust remover and a preparation method thereof, a method for removing dust from raw gas for sulfuric acid synthesis, and a method for preparing sulfuric acid by a wet process. Background Art

[0002] With the adjustment of industrial structure and the need for oil product upgrading, the technology of direct sulfuric acid production from waste gas generated by cracking of alkylation waste acid has developed rapidly. With the upgrading of National VI products and environmental protection requirements, my country's alkylation units are built on a large scale. The supporting waste acid regeneration unit regenerates the waste acid into 98% (mass fraction) concentrated sulfuric acid and sends it to the alkylation unit for recycling, reducing the treatment cost of sending waste acid and meeting environmental protection requirements.

[0003] The technologies widely used in the field of wet sulfuric acid production mainly include the Danish Topsoe WAS process technology and the Austrian P&P SOP process technology. Both technologies include an incineration part and a dust removal unit. The purpose of dust removal is to remove the Fe generated by the incineration part. 3+ 、Na + , K + Metal oxides or sulfates, etc., can clog subsequent pipelines and equipment, causing the catalyst to accumulate and become inactive. Traditional dust removal technologies mainly include electrostatic dust removal and high-temperature ceramic filter elements. The former has complex equipment and safety issues, and can only capture fine dust particles larger than 0.01μm; the latter has disadvantages such as reduced purification efficiency in the later stages, a high rate of filter element damage, and limited gas handling capacity. Summary of the invention

[0004] The purpose of the present invention is to provide a dust remover that can be applied to sulfuric acid process and its preparation method and application, especially to purify fine dust in raw gas from an incinerator.

[0005] The present invention believes that industrial sulfuric acid catalysts, especially wet sulfuric acid catalysts, often "caking", mostly fine dust (20-100nm) produced in the conversion furnace sulfate, mainly caused by iron sulfate deposition on the catalyst surface. Therefore, removing fine dust, especially iron oxide, is the key to protecting the long-term efficient and stable operation of sulfuric acid process catalysts.

[0006] The main feature of the present invention is to creatively propose a raw gas purification scheme for loading a dust remover in a sulfuric acid process converter by analyzing the dust-containing characteristics of the incinerator tail gas in the sulfuric acid process, and to utilize the physical and chemical adsorption effects of the dust remover on fine dust to retain the fine dust in the dust remover layer, thereby protecting the stable operation of the sulfuric acid catalyst.

[0007] According to a first aspect of the present invention, there is provided a dust remover for raw gas for sulfuric acid synthesis, the dust remover comprising an adsorbent and a carrier, wherein the adsorbent is at least one of heat-resistant fiber and sodium silicate.

[0008] According to a second aspect of the present invention, there is provided a method for preparing the dust remover, the method comprising: soaking the adsorbent in polyethylene glycol and ultrasonically treating it for 30 to 60 minutes, then dispersing the soaked adsorbent and the carrier in water, stirring for 10 to 20 minutes, performing solid-liquid separation, and drying, roasting and molding the solid to obtain the dust remover.

[0009] According to a third aspect of the present invention, there is provided a method for removing dust from raw gas for sulfuric acid synthesis, the method comprising: activating the dust remover of the present invention, and then contacting the raw gas for sulfuric acid synthesis with the activated dust remover.

[0010] According to a fourth aspect of the present invention, there is provided a method for preparing sulfuric acid by a wet process, the method comprising:

[0011] A dust remover bed and a catalyst bed are loaded in the reactor along the material flow direction; after loading into the reactor and before use, the dust remover bed is activated, and then raw gas is introduced. After the raw gas is dedusted by the dust remover, it enters the catalyst bed for catalytic reaction to synthesize sulfuric acid. The dust remover includes the dust remover described in the present invention.

[0012] The dust remover of the present invention can absorb and capture fine dust particles within the range of 20 to 100 nm.

[0013] After using the dust remover of the present invention, the Fe content at the outlet of the dust remover can be guaranteed to be within 50 ppb.

[0014] The present invention creatively proposes to adopt the technical means of filling dust removal agent to remove fine dust with a particle size of 20 to 50 nm in the tail gas of the sulfuric acid process incinerator. The Fe2O3 content at the dust removal agent outlet can be reduced to below 50 ppb, which can effectively ensure the stable operation of the sulfuric acid catalyst. DETAILED DESCRIPTION

[0015] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0016] The present invention provides a raw gas dust remover for sulfuric acid synthesis, the dust remover comprises an adsorbent and a carrier, the adsorbent is at least one of heat-resistant fiber and sodium silicate. The dust remover of the present invention can adsorb and capture fine dust within the range of 20 to 100 nm.

[0017] In the present invention, there is no special requirement for the source of the carrier, and commonly used carrier raw materials can be used in the present invention. The following exemplary description, but not limiting the scope of the present invention, the carrier is one of aluminum oxide, silicon oxide, and molecular sieve.

[0018] The present invention has no special requirements on the properties of the aluminum oxide, and commonly used aluminum oxides can be used in the present invention, which will not be listed one by one in the present invention.

[0019] The present invention has no special requirements on the properties of the silicon oxide, and commonly used silicon oxides can be used in the present invention, and the present invention will not list them one by one here.

[0020] In the present invention, heat-resistant fiber refers to high temperature resistant fiber, such as high temperature resistant fiber that can withstand (500-800)°C or above. Fibers that meet the aforementioned high temperature resistant performance can be used in the present invention. The following is an exemplary description, but it does not limit the scope of the present invention. The heat-resistant fiber is selected from at least one of polytetrafluoroethylene fiber, polyimide fiber and glass fiber.

[0021] In the present invention, all fibers that meet the heat resistance requirement can be applied to the present invention. The following is an exemplary description, but does not limit the scope of the present invention.

[0022] For example, the average molecular weight of polytetrafluoroethylene fiber is 1 million to 2 million, and the elastic modulus is 70 to 90 mPa.

[0023] For example, the average molecular weight of polyimide fiber is 100,000 to 400,000, and the elastic modulus is 70 to 80 mPa.

[0024] For example, the fiber diameter of glass fiber is 6 to 7 μm and the elastic modulus is 70 to 80 mPa.

[0025] In the present invention, any dust remover that meets the above requirements can be used in the present invention, and the optional range of its composition content is relatively wide. The following is an exemplary description, but it does not limit the scope of the present invention. Based on the total weight of the dust remover, the mass percentage of the adsorbent is 5% to 15%, and the mass percentage of the carrier is 85% to 95%.

[0026] The dust remover of the present invention can adsorb and capture fine dust particles within the range of 20 to 100 nm, and is particularly suitable for capturing dust particles in raw gas for synthesizing sulfuric acid.

[0027] The present invention has no special requirements for the preparation method of the dust remover. All dust removers that meet the above requirements can be used in the present invention. The following exemplary method for preparing the dust remover is given, but the method of the present invention cannot be limited to this method. According to one embodiment of the present invention, the present invention provides a method for preparing the dust remover of the present invention, which comprises: soaking the adsorbent in polyethylene glycol for ultrasonic treatment for 30 to 60 minutes, then dispersing the soaked adsorbent and the carrier in water, stirring for 10 to 20 minutes, performing solid-liquid separation, and drying, roasting, and molding the solid to obtain the dust remover. The above method has the advantages of strong dust removal ability of the dust remover to capture 20 to 100 nm dust, low dust removal cost, convenient replacement, and economy.

[0028] In the present invention, there is no special requirement for polyethylene glycol, and commonly used polyethylene glycol can be used in the present invention. The average molecular weight range is 200-1000. In the embodiments of the present invention, polyethylene glycol 200 is used as an example to illustrate the advantages of the present invention.

[0029] The dust remover required by the present invention can be prepared according to the aforementioned method. According to a preferred embodiment of the present invention, the temperature of the ultrasonic treatment is 25-70°C.

[0030] In the present invention, there is no special requirement for the drying, calcining and molding methods, and the following is an exemplary description, but the scope of the present invention is not limited thereby;

[0031] For example, the drying conditions include: a drying temperature of 100 to 120° C., and / or a drying time of 2 to 4 hours;

[0032] For example, the calcination conditions include: a calcination temperature of 300 to 500° C. and a calcination time of 1 to 2 hours.

[0033] The forming method is, for example, sheet forming, and the specific size is determined according to the actual application.

[0034] The dust remover of the present invention is particularly suitable for dust removal of raw gas for sulfuric acid synthesis. When used for dust removal of raw gas for sulfuric acid synthesis, the Fe content at the outlet of the dust remover is within 50 ppb.

[0035] The present invention provides a method for removing dust from raw gas for sulfuric acid synthesis, which comprises: activating the dust remover of the present invention, and then contacting the raw gas for sulfuric acid synthesis with the activated dust remover.

[0036] In the present invention, activation is generally carried out at room temperature and pressure, and there is no special requirement for its steps and methods. For example, it includes using a space velocity of 10000 to 20000h -1 The air is used for activation, and the water content of the air is controlled within 1g per cubic meter of air; the activation time is 2 to 5 hours.

[0037] The present invention is suitable for dust removal of various raw gas used for sulfuric acid synthesis. Specifically, for example, in the raw gas used for sulfuric acid synthesis, the dust particle size is 20-100 nm.

[0038] In the present invention, there is no requirement for the composition of the raw gas. If the dust content is high, the replacement cycle of the dust remover of the present invention is short, and if the dust content is low, the replacement cycle of the dust remover of the present invention is long.

[0039] The raw gas for sulfuric acid synthesis of the present invention may come from various sources. Generally, for example, the raw gas for sulfuric acid synthesis comes from a hydrogen sulfide incinerator and / or an alkylation waste acid incinerator.

[0040] The present invention provides a method for preparing sulfuric acid by a wet process, the method comprising:

[0041] Along the material flow direction, a dust removal agent bed layer and a catalyst bed layer are loaded in the reactor; after loading into the reactor and before use, the dust removal agent bed layer is activated, and then raw gas is introduced, and the raw gas enters the catalyst bed layer for catalytic reaction to synthesize sulfuric acid after being dusted by the dust removal agent, and the dust removal agent includes the dust removal agent of the present invention. The method of the present invention can prevent the catalyst from becoming compacted due to adsorbed dust, causing the bed layer resistance to increase and affecting production by first removing dust from the raw gas.

[0042] In the present invention, the activation steps and the source of the raw gas have been described in detail above.

[0043] For example, the activation step includes using a space velocity of 10,000 to 20,000 h -1 The air is used for activation, and the water content of the air is controlled within 1g per cubic meter of air; the activation time is 2 to 5 hours.

[0044] For example, in the raw gas, the dust particles have a size of 20-100 nm, preferably 20-50 nm.

[0045] In the present invention, there is no requirement for the composition of the raw gas. If the dust content is high, the replacement cycle of the dust remover of the present invention is short, and if the dust content is low, the replacement cycle of the dust remover of the present invention is long.

[0046] In the present invention, the raw gas generally contains SO2, water vapor, air and dust such as Fe2O3.

[0047] For example, the raw gas comes from a hydrogen sulfide incinerator and / or an alkylation waste acid incinerator.

[0048] According to a specific embodiment of the present invention, the reactor is a converter, and the dust remover is installed in the upper layer of the catalyst in the converter.

[0049] According to the method of the present invention, the Fe content at the outlet of the dust remover is within 50 ppb.

[0050] The present invention has no special requirements for the conditions of catalytic reaction for synthesizing sulfuric acid. In the embodiment, the temperature is 485°C and the air velocity is 10000h -1 Conduct the experiment description.

[0051] The following examples are only used to further explain the content and effects of the present invention, rather than to limit the present invention.

[0052] In the following examples, polytetrafluoroethylene fiber, polyimide fiber, glass fiber, and sodium silicate are all commercial products.

[0053] In the following examples, aluminum oxide and silicon oxide were purchased commercially.

[0054] In the present invention, the Fe2O3 content is detected by a conventional ICP method, 100 mL of gas is passed into a dilute nitric acid solution, and then the Fe content is determined by the ICP method, and then the gas content is expressed in the form of Fe2O3.

[0055] SO2 conversion rate = (inlet SO2 concentration - outlet SO2 concentration) / inlet SO2 concentration * 100%, SO2 concentration is detected by HYCL-8000 microcomputer fully automatic sulfur tester.

[0056] In the present invention, relative activity is defined as the activity of D1 dust remover as 100, and the ratio of the activity of other dust removers to that of D1 is used for calculation.

[0057] Example 1

[0058] Polytetrafluoroethylene fiber was used as the adsorbent and alumina was used as the carrier, with the mass ratio of adsorbent to carrier being 5 / 95. The adsorbent was soaked in polyethylene glycol at 25°C for 30 minutes and then ultrasonically treated. The soaked adsorbent and carrier were then dispersed in water and stirred for 10 minutes. After centrifugal separation, the obtained solid was dried at 100°C for 2 hours, calcined at 300°C for 1 hour in an air atmosphere, and formed into a φ5×5mm cylindrical shape. The obtained dust remover was named D1.

[0059] Example 2

[0060] Polyimide fiber was used as the adsorbent and silica as the carrier, with the mass ratio of adsorbent to carrier being 7 / 93. The adsorbent was soaked in polyethylene glycol at 30°C for 40 minutes and then ultrasonically treated. The soaked adsorbent and carrier were then dispersed in water and stirred for 15 minutes. After centrifugation, the obtained solid was dried at 100°C for 3 hours, calcined at 350°C for 1.5 hours in an air atmosphere, and formed into a φ5×5mm cylindrical shape. The obtained dust remover was named D2.

[0061] Example 3

[0062] Glass fiber was used as the adsorbent and ZSM-5 molecular sieve was used as the carrier, with the mass ratio of adsorbent to carrier being 10 / 90. The adsorbent was soaked in polyethylene glycol at 35°C for 50 minutes and then dispersed in water and stirred for 20 minutes. After centrifugation, the obtained solid was dried at 100°C for 4 hours, calcined at 400°C for 2 hours in an air atmosphere, and rolled into a φ3 mm sphere. The obtained dust remover was named D3.

[0063] Example 4

[0064] Sodium silicate was used as the adsorbent and alumina as the carrier, with the adsorbent / carrier mass ratio of 12 / 88. The adsorbent was soaked in polyethylene glycol at 40°C for 60 minutes and then ultrasonically treated. The soaked adsorbent and carrier were then dispersed in water and stirred for 20 minutes. After centrifugation, the obtained solid was dried at 120°C for 4 hours, calcined at 400°C for 2 hours in an air atmosphere, and rolled into a φ3 mm sphere. The obtained dust remover was named D4.

[0065] Example 5

[0066] Polytetrafluoroethylene fiber and sodium silicate were used as adsorbents, and alumina was used as a carrier, with a mass ratio of polytetrafluoroethylene fiber / sodium silicate / carrier of 7 / 8 / 85. The mixed adsorbent was soaked in polyethylene glycol at 50°C for 60 minutes and then ultrasonically treated. The soaked adsorbent and carrier were then dispersed in water and stirred for 20 minutes. After centrifugal separation, the obtained solid was dried at 120°C for 4 hours, calcined at 500°C for 2 hours in an air atmosphere, and rolled into a φ3 mm sphere. The obtained dust remover was named D5.

[0067] Example 6

[0068] Glass fiber and sodium silicate were used as adsorbents, and alumina was used as a carrier, with a mass ratio of glass fiber / sodium silicate / carrier of 7 / 8 / 85. The mixed adsorbent was soaked in polyethylene glycol at 60°C for 60 minutes and then ultrasonically treated. The soaked adsorbent and carrier were then dispersed in water and stirred for 20 minutes. After centrifugal separation, the obtained solid was dried at 120°C for 4 hours, calcined at 500°C for 2 hours in an air atmosphere, and formed into a φ6×4mm cylindrical shape. The obtained dust remover was named D6.

[0069] Example 7

[0070] Polyimide fiber and sodium silicate were used as adsorbents, alumina was used as a carrier, and the mass ratio of glass fiber / sodium silicate / carrier was 10 / 5 / 85. The mixed adsorbent was soaked in polyethylene glycol at 70°C for 60 minutes and then ultrasonically treated. The soaked adsorbent and carrier were then dispersed in water and stirred for 20 minutes. After centrifugation, the obtained solid was dried at 120°C for 4 hours, calcined at 500°C for 2 hours in an air atmosphere, and formed into a φ6×4mm cylindrical shape. The obtained dust remover was named D7.

[0071] Performance test: The converter adopts a jacketed single-tube reactor with a tube diameter of φ36×2mm. The temperature measuring thermocouple sleeve is located in the center of the converter with a tube diameter of φ8×1.5mm. First, the wet acid production catalyst is loaded, using NWS-1 wet acid production catalyst with a catalyst particle size of 3.35-4.0mm and a catalyst loading of 30mL. Then, 20mL of dust removal agent is loaded. At normal temperature and pressure, the air velocity is 15000h -1 , in situ activation with air (the water content of the air is controlled within 1g per cubic meter of air); then the temperature is raised to 485°C under normal pressure, and the atmosphere is switched to raw gas, the volume composition of the raw gas is 10% SO2 + 10% water vapor + 1-2ppm Fe2O3 (particle size distribution: 20-50nm) + balance air, and the air velocity is 10000h -1 ; The test results are shown in Table 1.

[0072] Table 1

[0073]

[0074] It can be seen from Table 1 that, compared with the blank test (filled with alumina), the dust remover of the present invention can effectively intercept Fe2O3 in the sulfuric acid process raw gas, thereby improving the stability of the catalyst.

[0075] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various specific technical features in any suitable manner. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. However, these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A dust remover for raw gas used for sulfuric acid synthesis, characterized in that: The dust remover comprises an adsorbent and a carrier, wherein the adsorbent is at least one of heat-resistant fiber and sodium silicate.

2. The dust remover according to claim 1, wherein: The carrier is one of aluminum oxide, silicon oxide and molecular sieve.

3. The dust remover according to claim 1 or 2, wherein: The heat-resistant fiber is selected from at least one of polytetrafluoroethylene fiber, polyimide fiber and glass fiber; Preferably, The average molecular weight of polytetrafluoroethylene fiber is 1 million to 2 million, and the elastic modulus is 70 to 90 mPa; and / or The average molecular weight of polyimide fiber is 100,000 to 400,000, and the elastic modulus is 70 to 80 mPa; and / or The fiber diameter of the glass fiber is 6 to 7 μm, and the elastic modulus is 70 to 80 mPa.

4. The dust remover according to any one of claims 1 to 3, wherein: Based on the total weight of the dust remover, the mass percentage of the adsorbent is 5% to 15%, and the mass percentage of the carrier is 85% to 95%; and / or The dust remover can adsorb and capture fine dust particles within the range of 20 to 100 nm.

5. A method for preparing the dust remover according to any one of claims 1 to 4, characterized in that: The method comprises: soaking the adsorbent in polyethylene glycol for ultrasonic treatment for 30 to 60 minutes, dispersing the soaked adsorbent and carrier in water, stirring for 10 to 20 minutes, performing solid-liquid separation, and drying, roasting and molding the solid to obtain the dust remover.

6. The preparation method according to claim 5, wherein: The average molecular weight of polyethylene glycol is 200-1000; and / or The temperature of the ultrasonic treatment is 25-70°C; and / or The drying conditions include: a drying temperature of 100 to 120° C., and / or a drying time of 2 to 4 hours; and / or The calcination conditions include: a calcination temperature of 300 to 500° C. and a calcination time of 1 to 2 hours.

7. A method for removing dust from raw gas for sulfuric acid synthesis, the method comprising: Activating the dust remover according to any one of claims 1 to 4, and then contacting the raw gas for sulfuric acid synthesis with the activated dust remover; Preferably, The activation step includes using a space velocity of 10000 to 20000 h -1 The air is activated, and the water content of the air is controlled within 1g per cubic meter of air; the activation time is 2 to 5 hours; and / or Preferably, the raw gas for sulfuric acid synthesis comes from a hydrogen sulfide incinerator and / or an alkylation waste acid incinerator.

8. A method for preparing sulfuric acid by a wet process, characterized in that: The method includes: A dust remover bed and a catalyst bed are loaded in the reactor along the material flow direction; after loading into the reactor and before use, the dust remover bed is activated, and then raw gas is introduced. After the raw gas is dedusted by the dust remover, it enters the catalyst bed for catalytic reaction to synthesize sulfuric acid, and the dust remover includes the dust remover described in any one of requirements 1-4.

9. The method according to claim 8, wherein: The activation step includes using a space velocity of 10000 to 20000 h -1 The air is activated, and the water content of the air is controlled within 1g per cubic meter of air; the activation time is 2 to 5 hours; and / or The raw gas comes from a hydrogen sulfide incinerator and / or an alkylation waste acid incinerator.

10. The method according to claim 9, wherein: The reactor is a reformer, and the dust remover is installed on the upper layer of the catalyst in the reformer; and / or The Fe content at the dust collector outlet is within 50ppb.

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