A method for recycling and treating polyacrylonitrile waste gas resources

Abstract

The application provides a polyacrylonitrile waste gas resource treatment and recovery method, and belongs to the technical field of petrochemical waste gas resource utilization, and comprises the following steps: S1, polyacrylonitrile waste gas is subjected to water spraying and condensation, and the obtained waste gas passes through a macroporous styrene adsorption resin column; S2, the resin column adsorbed with acrylonitrile is subjected to stripping with steam; S3, the stripped acrylonitrile and steam mixture is condensed through a spiral plate heat exchanger, and the condensate is separated into layers through an oil-water separator to recover acrylonitrile; and S4, the resin column after stripping is subjected to rinsing with distilled water to reduce the temperature of the resin, and the resin is reused. The application recovers acrylonitrile in waste gas by using a resin adsorption method, regenerates the resin by using low-pressure steam, recovers acrylonitrile by oil-water separation, then sprays the resin with distilled water to reduce the temperature of the resin, and the resin is adsorbed again. Finally, acrylonitrile is recovered and pollution is reduced.

Description

Technical Field

[0001] This invention relates to the field of petrochemical waste gas resource utilization technology, specifically to a method for the resource-based treatment and recovery of polymer acrylonitrile waste gas. Background Technology

[0002] Acrylonitrile is one of the three major raw materials for synthetic materials, playing a significant role and having broad application prospects in synthetic resins, synthetic fibers, and synthetic rubber. Currently, about 50% of the world's acrylonitrile products are used in the production of acrylonitrile fibers. While acrylonitrile production in Western countries is decreasing year by year, its consumption in the synthesis of carbon fibers is increasing. my country has significantly expanded its carbon fiber production capacity. With the large-scale production of carbon fibers, the process of polymerizing and then carbonizing acrylonitrile generates increasing amounts of acrylonitrile-containing waste gas. Currently, most treatment methods rely on combustion, which is not only wasteful of resources but also produces nitrogen oxides, causing secondary pollution and incurring high treatment costs. Activated carbon fiber adsorption is difficult to meet national emission standards, and the use of adsorption resins for acrylonitrile waste gas treatment has not been practically applied or reported. Therefore, developing a new method for treating acrylonitrile waste gas is imperative.

[0003] With the continuous deterioration of environmental pollution, the country has strengthened its requirements and controls in the field of environmental protection, and has put forward new standards for various environmental pollutant emission indicators. In the latest "Emission Standard of Pollutants from Petrochemical Industry" (GB31571-2015), the emission concentration of acrylonitrile is ≤0.5mg / m³. 3 .

[0004] Currently, acrylonitrile-containing exhaust gas mainly exists in acrylonitrile plants and downstream industries such as ABS, acrylic fiber and carbon fiber precursors, and acrylamide production. There are nine acrylonitrile producers in China, most of which have installed absorption towers to treat exhaust gas. However, with the implementation of the latest "Emission Standard for Pollutants from Petrochemical Industry" (GB31571-2015), current treatment methods are no longer sufficient to meet the new emission requirements. There are currently nine acrylic fiber producers; except for a few with regenerative thermal oxidizers (RTOs) or activated carbon adsorption devices, most have not added exhaust gas treatment equipment. There are currently eight ABS producers, most of which currently use RTOs to treat exhaust gas, resulting in NOx emissions. x There is the issue of exports failing to meet standards. Additionally, manufacturers of acrylamide and nitrile rubber also have problems with their exhaust gases failing to meet the latest emission requirements.

[0005] Patent CN111760453A discloses an industrial volatile organic compound (VOC) waste gas treatment system. Its principle involves the gas flowing from inlet to outlet through an advanced oxidation section and a physical adsorption section. The advanced oxidation section includes a gas flow equalization plate, a UV photolysis section, and a photocatalytic section. An activated carbon layer is added to the rear end of each row of lamps in the UV photolysis section. This system can further purify incompletely combusted and decomposed gases, as well as treat nitrogen oxides generated at the front end, ultimately achieving emission standards.

[0006] Patent CN111457404A discloses a safe regenerative catalytic oxidation device for organic waste gas. Its key feature is its suitability for safely treating low-concentration, high-volume organic waste gas. After pretreatment, the organic waste gas is pressurized by a fan and enters the regenerative catalytic chamber and oxidation chamber. The regenerative catalytic chamber is filled with a heat storage medium and a catalyst. The organic waste gas is heated within the chamber and catalytically oxidized into water and carbon dioxide under the action of the catalyst and high temperature, achieving purification. To ensure the safety and stability of the organic waste gas treatment process, the complete device is equipped with a series of instruments and control systems. This ensures that the complete device can minimize potential hazards or achieve safe operation in various foreseeable emergency situations.

[0007] Patent CN111054186A discloses a rotary organic waste gas adsorption and concentration device for VOC waste gas treatment, relating to the field of organic waste gas treatment technology. It includes a housing containing an adsorption-desorption bed, an isolation mechanism, and a rotating mechanism. The adsorption-desorption bed is fixed within the housing by a mounting frame. The isolation mechanism includes a central shaft, isolation components, an upper cover plate, and a lower cover plate. The rotating mechanism includes a motor, a driving gear, and a driven gear. This design allows for simultaneous adsorption and desorption processes, effectively utilizing the space within the device and improving the efficiency of gas adsorption and desorption. Summary of the Invention

[0008] The purpose of this invention is to propose a method for the resource-based treatment and recovery of polyacrylonitrile (PAC) waste gas. This method utilizes low-pressure steam to strip and regenerate the resin, separates the oil and water to recover acrylonitrile, and then sprays the resin with distilled water to cool it down, allowing the resin to re-adsorb. Ultimately, acrylonitrile is recovered, and pollution emissions are reduced.

[0009] The technical solution of this invention is implemented as follows:

[0010] This invention provides a method for the resource-based treatment and recovery of polyacrylonitrile waste gas, comprising the following steps:

[0011] S1. After the polyacrylonitrile waste gas is sprayed with water and condensed, the resulting waste gas is passed through a macroporous styrene adsorption resin column.

[0012] S2. The resin column adsorbed with acrylonitrile is stripped with steam;

[0013] S3. The acrylonitrile and steam mixture is condensed in a spiral heat exchanger, and the condensate is separated and the acrylonitrile is recovered by an oil-water separator.

[0014] S4. Rinse the stripped resin column with distilled water to lower the resin temperature, allowing the resin to be reused.

[0015] As a further improvement of the present invention, the concentration of acrylonitrile in the waste gas is 2000-3000 mg / Nm³. 3 .

[0016] As a further improvement of the present invention, the flow rate of the exhaust gas is 100-500 BV / h.

[0017] As a further improvement of the present invention, the macroporous styrene-based adsorption resin is selected from any one of Innovate-30 macroporous adsorption resin, Amberlite XDA-7 macroporous adsorption resin, Amberlite XDA-4 macroporous adsorption resin, and XDA-1 macroporous adsorption resin.

[0018] As a further improvement of the present invention, the macroporous styrene-based adsorption resin is Innovate-30 macroporous adsorption resin.

[0019] As a further improvement of the present invention, in step S2, low-temperature steam is used for stripping.

[0020] As a further improvement of the present invention, the temperature of the low-temperature steam is 120-130°C.

[0021] As a further improvement of the present invention, the steam desorption flow rate is 200-500 kg / h.

[0022] This invention utilizes resin adsorption to treat and recover acrylonitrile from waste gas. Low-pressure steam is used to strip and regenerate the resin, followed by oil-water separation to recover acrylonitrile. Then, distilled water is sprayed onto the resin to cool it, allowing for re-adsorption. Ultimately, acrylonitrile is recovered, reducing pollution emissions.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The process of this invention is simple, the raw material input is single and small in quantity, the cost is low, the acrylonitrile recovery effect is significant, the acrylonitrile content in the waste gas is greatly reduced, the product in the waste gas can be recovered, and air pollution is reduced.

[0025] 2. This invention improves operational safety. The adsorbent itself contains a large amount of bound water, and the spray system in the equipment design accelerates the rapid release of static electricity, resulting in a high safety factor. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] The acrylonitrile content in the waste gas from the acrylonitrile production of a petrochemical company is 2000-3000 mg / Nm³. 3 It has an odor; the specific recycling and disposal methods are as follows:

[0029] 1. At room temperature, acrylonitrile waste gas was sprayed and condensed for cooling, then passed through a resin column packed with 40L each of Innovate-30 macroporous adsorption resin at a flow rate of 200 BV / h. The acrylonitrile content in the waste gas (adsorption outlet) after column passing was measured and reduced to 0.5 mg / Nm³. 3 the following.

[0030] 2. The resin column adsorbed with acrylonitrile is stripped using low-pressure steam (120-130℃);

[0031] 3. Collect the vapor desorption liquid, and condense the desorption liquid in a condenser to recover acrylonitrile.

[0032] 4. Rinse and cool the adsorption resin column with distilled water, and reuse the resin column.

[0033] The acrylonitrile waste gas and the column-passed waste gas after treatment of different waste gas volumes were detected by high performance liquid chromatography, and the results are shown in Table 1.

[0034] Table 1. Adsorption effect of Innovate-30 adsorption resin on acrylonitrile waste gas

[0035] <![CDATA[Processing acrylonitrile waste gas volume (m 3 )]]> <![CDATA[Acrylonitrile concentration (mg / Nm 3 )]]> raw exhaust gas 2462 15 Not detected 30 Not detected 45 0.2 60 0.3 75 0.3 90 0.5

[0036] As shown in Table 1, treatment with Innovate-30 adsorption resin for 15m 3 and 30m 3 During the waste gas treatment, no acrylonitrile was detected in the waste gas at the column outlet, indicating that the acrylonitrile in the waste gas was completely adsorbed. This process treated 90m³ of waste gas. 3 Afterwards, the adsorption rate of acrylonitrile can still reach over 99.97%, and the content of acrylonitrile at the outlet meets the national waste gas emission standards. After stripping with low-pressure steam, the desorption rate can reach over 99%, and the desorbed acrylonitrile can be directly reused in production, indicating that the method of the present invention has a significant effect on the resource-based treatment and recovery of acrylonitrile waste gas.

[0037] Example 2

[0038] Following the method in Example 1, XAD-4 adsorption resin was used to adsorb 15 Nm 3 Acrylonitrile waste gas at a rate of 50 BV / h was treated and recovered for resource utilization. The treated waste gas was tested every hour, and the test results are shown in Table 2.

[0039] Table 2 XAD-4 adsorption resin at 15 Nm 3 Adsorption effect on acrylonitrile waste gas at / h

[0040] Treatment time for acrylonitrile waste gas <![CDATA[Acrylonitrile concentration (mg / Nm 3 )]]> 0 2342 1 0.9 2 2.7 3 5.2 4 15.3 5 40.9 6 83.5

[0041] As shown in Table 2, the XAD-4 macroporous adsorption resin does not meet the emission requirements for the resource recovery and treatment of acrylonitrile waste gas.

[0042] Example 3

[0043] Following the method in Example 1, XDA-1 adsorption resin was used to adsorb 15 Nm 3 The acrylonitrile waste gas was treated and recovered for resource utilization. The treated waste gas was tested every hour, and the test results are shown in Table 3.

[0044] Table 3 XDA-1 adsorption resin at 15 Nm 3 Adsorption effect on acrylonitrile waste gas at / h

[0045] Treatment time for acrylonitrile waste gas <![CDATA[Acrylonitrile concentration (mg / Nm 3 )]]> 0 2473 1 0.6 2 1.9 3 4.3 4 11.3 5 24.9 6 45.8

[0046] As shown in Table 3, the XDA-1 macroporous adsorption resin does not meet the emission requirements for the resource recovery and treatment of acrylonitrile waste gas.

[0047] Example 4

[0048] Following the method in Example 1, XAD-7 adsorption resin was used to adsorb 15 Nm 3 The acrylonitrile waste gas was treated and recovered for resource utilization. The treated waste gas was tested every hour, and the test results are shown in Table 3.

[0049] Table 4. XAD-7 adsorption resin at a flow rate of 15 Nm 3 Adsorption effect on acrylonitrile waste gas at / h

[0050] Treatment time for acrylonitrile waste gas <![CDATA[Acrylonitrile concentration (mg / Nm 3 )]]> 0 2358 1 0.8 2 2.6 3 5.9 4 13.3 5 28.8 6 52.7

[0051] As shown in Table 4, the XAD-7 macroporous adsorption resin does not meet the emission requirements for the resource-based treatment and recovery of acrylonitrile waste gas.

[0052] Example 5

[0053] Following the method in Example 1, XAD-7 adsorption resin was used to adsorb 30 Nm 3The acrylonitrile waste gas was treated and recovered for resource utilization. The treated waste gas was tested every hour, and the test results are shown in Table 3.

[0054] Table 5 XAD-7 adsorption resin at a flow rate of 15 Nm 3 Adsorption effect on acrylonitrile waste gas at / h

[0055]

[0056]

[0057] As shown in Table 5, the XAD-7 macroporous adsorption resin, applied at a flow rate of 750 BV / h, failed to meet emission requirements for the resource recovery and treatment of acrylonitrile waste gas.

[0058] Example 6

[0059] Following the method in Example 1, Innovate-30 adsorption resin was used to adsorb 30 Nm 3 The acrylonitrile waste gas was treated and recovered for resource utilization. The treated waste gas was tested every hour, and the test results are shown in Table 3.

[0060] Table 6 Innovate-30 adsorption resin at a flow rate of 30 Nm 3 Adsorption effect on acrylonitrile waste gas at / h

[0061] Treatment time for acrylonitrile waste gas <![CDATA[Acrylonitrile concentration (mg / Nm 3 )]]> 0 2326 1 0.2 2 0.5 3 0..9 4 2.3 5 5.8 6 12.7

[0062] As shown in Table 6, the Innovate-30 macroporous adsorption resin showed a significantly better performance in the resource recovery of acrylonitrile waste gas at a flow rate of 750 BV / h compared to that at a flow rate of 100-500 BV / h. This is because acrylonitrile has a shorter residence time in the macroporous adsorption resin.

[0063] Example 7

[0064] Following the method in Example 1, Innovate-30 adsorption resin was used to adsorb 15 Nm 3 The acrylonitrile waste gas was treated and recovered for resource utilization. The stripping was carried out with a steam temperature of 100℃. After regeneration, the treated waste gas was tested every hour. The test results are shown in Table 7.

[0065] Table 7 shows the adsorption performance of Innovate-30 adsorbent resin after stripping at 100°C and a flow rate of 15 Nm. 3 Adsorption effect at / h

[0066] Treatment time for acrylonitrile waste gas <![CDATA[Acrylonitrile concentration (mg / Nm 3 )]]> 0 2322 1 0.2 2 0.5 3 0..9 4 2.3 5 5.8 6 12.7

[0067] As shown in Table 7, the Innovate-30 macroporous adsorption resin performed worse in the resource recovery and treatment of acrylonitrile waste gas at a stripping temperature of 100℃ than at 120-130℃. This is because the acrylonitrile adsorbed by the macroporous adsorption resin was not completely stripped, resulting in poor performance in the next cycle.

[0068] Example 8

[0069] Following the method in Example 1, Innovate-30 adsorption resin was used to adsorb 15 Nm 3 The acrylonitrile waste gas was treated and recovered for resource utilization using methanol solvent washing and regeneration. After regeneration, the treated waste gas was tested every hour. The test results are shown in Table 8.

[0070] Table 8 shows the Innovate-30 adsorption resin after methanol elution at a flow rate of 15 Nm. 3 Adsorption effect at / h

[0071]

[0072]

[0073] As shown in Table 8, the Innovate-30 macroporous adsorption resin, when using methanol as the eluent, has a similar effect to steam stripping in the resource-based treatment and recovery of acrylonitrile waste gas. However, considering safety and operating costs, steam operation has lower operating costs.

[0074] Example 9

[0075] After selecting a large number of adsorption resins, Innovate-30 was used to adsorb 1500 Nm according to the method in Example 1. 3 The acrylonitrile waste gas was treated and recovered in a resource-based manner. Examples 1-8 were pilot-scale tests with a small amount of adsorption resin, only 80 liters. This example is a production process that treats 1500 cubic meters of tail gas with a large amount of adsorption resin, 3 cubic meters. The treated waste gas was tested once for each small-scale test, and the results are shown in Table 9.

[0076] Table 9. Innovate-30 adsorption resin for 1500 Nm 3 Adsorption effect of acrylonitrile waste gas

[0077] Treatment time for acrylonitrile waste gas <![CDATA[Acrylonitrile concentration (mg / Nm 3 )]]> 0 2542 1 Not detected 2 Not detected 3 0.2 4 0.3 5 0.3 6 0.5

[0078] As shown in Table 9, Innovate-30 macroporous adsorption resin has a significant effect on the resource recovery and treatment of acrylonitrile waste gas, achieving the national emission standard of ≤0.5mg / Nm³ for acrylonitrile content. 3 It can be widely promoted in industries such as petrochemicals to achieve a double harvest of economic and environmental benefits.

[0079] This project studies the treatment efficiency of acrylonitrile waste gas using material adsorption. This technology is not only highly suitable for acrylonitrile tail gas adsorption and recovery in the acrylonitrile fiber division, but also has significant potential for wider application in Sinopec's Qilu Petrochemical and Anqing Petrochemical plants. Furthermore, this technology can be extended to carbon fiber precursor production, particularly under the current stringent environmental regulations. It is of great significance for the acrylonitrile tail gas treatment of Shanghai Petrochemical's 10,000-ton-scale large-tow precursor project, and also has immense application value and broad market prospects for similar waste gas purification in other industries.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for resource-based treatment and recovery of polyacrylonitrile waste gas, characterized in that, Includes the following steps: S1. After the polyacrylonitrile waste gas is sprayed with water and condensed, the resulting waste gas is passed through a macroporous styrene adsorption resin column. S2. The resin column adsorbed with acrylonitrile is stripped with low-temperature steam at 120-130℃ at a flow rate of 200-500Kg / h; S3. The acrylonitrile-stripped mixture with steam is condensed in a spiral plate heat exchanger, and the condensate is separated and the acrylonitrile is recovered by an oil-water separator. S4. Rinse the stripped resin column with distilled water to lower the resin temperature and reuse the resin. The macroporous styrene-based adsorption resin is Innovate-30 macroporous adsorption resin, and the acrylonitrile concentration in the treated waste gas is ≤0.5 mg / Nm³.

2. The method for resource-based treatment and recovery of polyacrylonitrile waste gas according to claim 1, characterized in that, The concentration of acrylonitrile in the exhaust gas is 2000-3000 mg / Nm³. 3 .

3. The method for resource-based treatment and recovery of polyacrylonitrile waste gas according to claim 1, characterized in that, The flow rate of the exhaust gas is 100-500 BV / h.

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