Industrial tail gas treatment method

Abstract

The invention belongs to the technical field of environmental pollution treatment, and particularly relates to an industrial tail gas treatment method. The industrial tail gas treatment method provided by the invention comprises the following steps: carrying out countercurrent adsorption on a beta-cyclodextrin solution and industrial tail gas in an adsorption tower to obtain purified industrial tail gas, the mass concentration of the beta-cyclodextrin solution is 2-3%. According to the invention, beta-cyclodextrin is prepared into an aqueous solution as an adsorbent for adsorbing volatile organic pollutants in industrial tail gas; in the adsorption process, continuous efficient adsorption can be achieved by continuously supplementing the beta-cyclodextrin aqueous solution, and the content of volatile organic pollutants (VOC) in the industrial tail gas can be reduced to 200 ppm. According to the method, the beta-cyclodextrin inclusion compound solid can be recycled after being regenerated.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental pollution control, and specifically relates to a method for treating industrial tail gas. Background Art

[0002] With the development of industry, organic pollutants, such as benzene series, contained in industrial exhaust gas discharged by chemical production not only endanger human health, but also pollute the environment. At present, adsorbents are mainly used to adsorb organic pollutants to reduce the content of organic pollutants in industrial waste gas. The existing adsorbents are mainly activated carbon with developed pore structure and large specific surface area. However, the adsorption capacity of activated carbon is limited. As the use time increases, the adsorbent will gradually become saturated and need to be replaced or regenerated regularly. Although activated carbon can be regenerated, the regeneration process requires high cost and technical requirements. Summary of the invention

[0003] In view of this, the present invention provides a method for treating industrial tail gas. The method provided by the present invention can efficiently adsorb volatile organic pollutants in industrial tail gas, and β-cyclodextrin as an adsorbent can be easily regenerated, which greatly reduces the cost of tail gas treatment.

[0004] In order to solve the above technical problems, the present invention provides a method for treating industrial tail gas, comprising the following steps:

[0005] The β-cyclodextrin solution and the industrial tail gas are subjected to countercurrent adsorption in an adsorption tower to obtain purified industrial tail gas;

[0006] The mass concentration of the β-cyclodextrin solution is 2-3%.

[0007] Preferably, the β-cyclodextrin solution is introduced into the adsorption tower in a top-down spraying manner.

[0008] Preferably, the spraying pressure is 0.3-0.6 MPa.

[0009] Preferably, the spray flow rate is 3 to 5 m 3 / h.

[0010] Preferably, the content of volatile organic pollutants in the industrial tail gas is 2000-15000 ppm.

[0011] Preferably, the flow rate of the industrial tail gas entering the adsorption tower is 3 to 5 m / s;

[0012] The contact time between the industrial tail gas and the beta-cyclodextrin solution in the adsorption tower is 1 to 2 seconds.

[0013] Preferably, the countercurrent adsorption includes primary countercurrent adsorption or secondary countercurrent adsorption;

[0014] The adsorption tower is provided with a Raschig ring filler;

[0015] The mass content of volatile organic pollutants in the tail gas after the primary countercurrent adsorption is 150 to 1500 ppm;

[0016] The mass content of volatile organic pollutants in the tail gas after the secondary countercurrent adsorption is 20 to 200 ppm.

[0017] Preferably, after the countercurrent adsorption, a β-cyclodextrin inclusion compound solid is obtained which settles at the bottom of the adsorption tower;

[0018] The regeneration method of the β-cyclodextrin inclusion compound solid comprises the following steps:

[0019] The β-cyclodextrin inclusion compound solid and the organic solvent are mixed and allowed to stand for solid-liquid separation to obtain regenerated β-cyclodextrin;

[0020] The organic solvent is an alcohol solvent.

[0021] Preferably, the mass ratio of the β-cyclodextrin inclusion complex solid to the organic solvent is 1:2-3.

[0022] Preferably, the standing time is 4 to 6 hours.

[0023] The present invention provides a method for treating industrial tail gas, comprising the following steps: countercurrently adsorbing a β-cyclodextrin solution and industrial tail gas in an adsorption tower to obtain purified industrial tail gas; the mass concentration of the β-cyclodextrin solution is 2-3%. In the present invention, the β-cyclodextrin molecule is composed of C, H, and O elements, and has a slightly conical hollow cylindrical three-dimensional ring structure. After the cavity adsorbs the organic pollutant gas, it will form an inclusion compound to achieve the adsorption of organic pollutants in the industrial tail gas. The present invention prepares β-cyclodextrin into an aqueous solution as an adsorbent to adsorb volatile organic pollutants in industrial tail gas; during the adsorption process, the present invention can achieve continuous and efficient adsorption by continuously adding a β-cyclodextrin aqueous solution, and can reduce the content of volatile organic pollutants (VOC) in industrial tail gas to 20 ～ 200ppm. The present invention can also regenerate the β-cyclodextrin inclusion compound solid through a simple method and then recycle it, and the water in the adsorption process can also be recycled. The treatment method provided by the present invention generates less waste, reduces secondary pollution, and reduces treatment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the ball-and-stick model diagram of β-cyclodextrin. DETAILED DESCRIPTION

[0025] The present invention provides a method for treating industrial tail gas, comprising the following steps:

[0026] The beta-cyclodextrin solution and the industrial tail gas are subjected to countercurrent adsorption in an adsorption tower to obtain purified industrial tail gas.

[0027] As a specific embodiment of the present invention, the mass concentration of the β-cyclodextrin solution is 2-3%, which can be specifically 2%, 2.3%, 2.5%, 2.8% or 3%; the ball-and-stick model of β-cyclodextrin in the β-cyclodextrin solution is as follows: Figure 1 shown.

[0028] In the present invention, the annular structure of β-cyclodextrin makes its outer edge hydrophilic and its inner cavity hydrophobic, and this property enables it to selectively adsorb non-polar substances; β-cyclodextrin forms a host-guest molecular complex with organic matter, and the organic matter is wrapped in the inner cavity through hydrophobic action to achieve adsorption of the organic matter; at the same time, β-cyclodextrin has a high specific surface area and adsorption capacity, and is suitable for large-scale atmospheric environmental pollution control.

[0029] As a specific embodiment of the present invention, the content of volatile organic pollutants in the industrial tail gas can be 2000-15000 ppm, or 4000-12000 ppm; the volatile organic pollutants can be one or more of o-dichlorobenzene, toluene and ethylbenzene.

[0030] As a specific embodiment of the present invention, when the industrial tail gas contains acidic gas, the industrial tail gas can be first passed through an alkaline solution to remove the acidic gas before countercurrent adsorption; the acidic gas includes one or more of hydrogen chloride, sulfur dioxide and carbon dioxide; the alkaline solution includes one or more of sodium hydroxide solution, potassium hydroxide, sodium carbonate and potassium carbonate. The present invention has no special restrictions on the amount and concentration of the alkaline solution, as long as the acidic gas in the industrial tail gas can be removed.

[0031] As a specific embodiment of the present invention, when the industrial tail gas contains acidic gas, the pH value of the β-cyclodextrin solution can be adjusted to 9 to 10, and then countercurrent adsorption is performed with the industrial tail gas, and the pH value of the β-cyclodextrin solution is maintained in the range of 9 to 10 during the countercurrent adsorption process. The present invention has no special requirements for the method of adjusting the pH value of the β-cyclodextrin solution, and the conventional method in the art can be used.

[0032] As a specific embodiment of the present invention, the β-cyclodextrin solution can be introduced into the adsorption tower in a spraying manner; the spraying pressure can be 0.3-0.6 MPa, specifically 0.3 MPa, 0.4 MPa, 0.5 MPa or 0.6 MPa; the spraying flow rate can be 3-5 m / s. 3 / h, which can be specifically 3m 3 / h、3.5m 3 / h、4m3 / h、4.5m 3 / h or 5m 3 / h. The present invention adopts a spraying method to pass the β-cyclodextrin solution into the adsorption tower, which is beneficial for the β-cyclodextrin solution to fully contact with the tail gas and improve the adsorption efficiency.

[0033] As a specific embodiment of the present invention, the flow rate of the industrial tail gas entering the adsorption tower can be 3-5 m / s, specifically 3 m / s, 4 m / s or 5 m / s; the contact time between the industrial tail gas and the β-cyclodextrin solution in the adsorption tower can be 1-2 s.

[0034] As a specific embodiment of the present invention, the β-cyclodextrin solution can be introduced into the adsorption tower from the top of the adsorption tower, and the industrial tail gas can be introduced into the adsorption tower from the bottom of the adsorption tower. The present invention uses the β-cyclodextrin aqueous solution as an adsorbent to adsorb volatile organic pollutants while also being able to adsorb small molecular gases that are easily soluble in water, thereby further reducing VOCs in the tail gas.

[0035] As a specific embodiment of the present invention, a Raschig ring filler can be arranged in the adsorption tower, and the height of the Raschig ring filler in the adsorption tower can be 0.5 to 0.7 m, and can be specifically 0.5 m, 0.55 m, 0.6 m, 0.65 m or 0.7 m. In the present invention, the filler is arranged in the adsorption tower to facilitate the formation of a water film to facilitate adsorption.

[0036] As a specific embodiment of the present invention, the countercurrent adsorption may include primary countercurrent adsorption or secondary countercurrent adsorption; the mass content of volatile organic pollutants in the industrial exhaust gas after primary countercurrent adsorption may be 150 to 1500 ppm, and the mass content of volatile organic pollutants in the industrial exhaust gas after secondary countercurrent adsorption may be 20 to 200 ppm.

[0037] As a specific embodiment of the present invention, after the countercurrent adsorption, a β-cyclodextrin inclusion compound solid can be obtained which settles at the bottom of the adsorption tower; the regeneration method of the β-cyclodextrin inclusion compound solid can include the following steps:

[0038] The β-cyclodextrin inclusion compound solid and the organic solvent are mixed and then allowed to stand for solid-liquid separation to obtain regenerated β-cyclodextrin.

[0039] As a specific embodiment of the present invention, the organic solvent may be an alcohol solvent, and the alcohol solvent may include methanol or ethanol; the mass ratio of the β-cyclodextrin inclusion compound solid to the organic solvent may be 1:2-3, and may be specifically 1:2, 1:2.5 or 1:3. As a specific embodiment of the present invention, the mixing may be carried out under stirring, and the stirring time may be 30-50 minutes, and may also be 35-45 minutes. The present invention has no special limitation on the stirring speed, as long as the mixing is uniform.

[0040] As a specific implementation of the present invention, the standing time may be 4 to 6 hours, specifically 4 hours, 4.5 hours, 5 hours, 5.5 hours or 6 hours; the solid-liquid separation may be filtration.

[0041] The regenerated beta-cyclodextrin obtained by the regeneration of the present invention can be repeatedly recycled, and the regeneration method provided by the present invention is simple and easy to operate.

[0042] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0043] Example 1

[0044] The industrial tail gas with a VOC content of 5000ppm (VOC is mainly o-dichlorobenzene) is the treatment object;

[0045] A Raschig ring packing with a height of 0.5 m was set in the adsorption tower; a β-cyclodextrin solution with a mass concentration of 2% was introduced from the top of the adsorption tower at a pressure of 0.4 MPa and a flow rate of 4 m 3 / h is sprayed into the adsorption tower, and the industrial tail gas is introduced into the adsorption tower from the bottom of the adsorption tower at a flow rate of 4m / s; the β-cyclodextrin solution and the industrial tail gas are subjected to secondary countercurrent adsorption in the adsorption tower (contact time is 2s) to obtain purified industrial tail gas and β-cyclodextrin inclusion compound solid settled at the bottom of the adsorption tower;

[0046] The β-cyclodextrin inclusion compound solid was mixed with methanol at a mass ratio of 1:2, stirred for 40 minutes, and then allowed to stand. After standing for 5 hours, it was filtered to obtain regenerated β-cyclodextrin.

[0047] Example 2

[0048] The industrial tail gas is purified according to the method of Example 1, except that a primary countercurrent adsorption is performed.

[0049] Example 3

[0050] The industrial tail gas is purified according to the method of Example 1, except that the adsorbent is replaced by a regenerated β-cyclodextrin aqueous solution instead of a β-cyclodextrin aqueous solution.

[0051] Comparative Example 1

[0052] The industrial tail gas with a VOC content of 5000ppm (VOC is mainly o-dichlorobenzene) is the treatment object;

[0053] Activated carbon is used as an adsorbent to adsorb industrial exhaust gas. Activated carbon with a height of 0.3m is set in the activated carbon absorption box for three-stage adsorption. The industrial exhaust gas is introduced from the bottom of the absorption box at a flow rate of 2m / s to obtain purified industrial exhaust gas VOC.

[0054] The VOC content in the purified industrial tail gas after treatment in Examples 1 to 3 and Comparative Example 1 was detected using a VOC measuring instrument, and the results are listed in Table 1.

[0055] Table 1 VOC content in the purified industrial tail gas after treatment in Examples 1 to 3 and Comparative Example 1

[0056]

[0057] Note: The VOC content in the purified industrial exhaust gas is the average value of six consecutive test results under normal production conditions, and the interval between two measurements is 20 minutes.

[0058] It can be seen from Table 1 that the method provided by the present invention can efficiently adsorb VOC in industrial tail gas. At the same time, the test results of Example 3 can prove that the regenerated β-cyclodextrin can also efficiently adsorb VOC in industrial tail gas, thereby reducing the cost of tail gas treatment.

[0059] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for treating industrial tail gas, comprising the following steps: The β-cyclodextrin solution and the industrial tail gas are subjected to countercurrent adsorption in an adsorption tower to obtain purified industrial tail gas; The mass concentration of the β-cyclodextrin solution is 2-3%.

2. The method for treating industrial tail gas according to claim 1, characterized in that: The β-cyclodextrin solution is introduced into the adsorption tower in a top-down spraying manner.

3. The method for treating industrial tail gas according to claim 2, characterized in that: The spraying pressure is 0.3-0.6 MPa.

4. The method for treating industrial tail gas according to claim 2, characterized in that: The spraying flow rate is 3 to 5 m 3 / h.

5. The method for treating industrial tail gas according to claim 1, characterized in that: The content of volatile organic pollutants in the industrial tail gas is 2000-15000 ppm.

6. The method for treating industrial tail gas according to claim 1 or 5, characterized in that: The flow rate of the industrial tail gas entering the adsorption tower is 3-5 m / s; The contact time between the industrial tail gas and the beta-cyclodextrin solution in the adsorption tower is 1 to 2 seconds.

7. The method for treating industrial tail gas according to claim 1, characterized in that: The countercurrent adsorption includes primary countercurrent adsorption or secondary countercurrent adsorption; Raschig ring filler is arranged in the adsorption tower; The mass content of volatile organic pollutants in the tail gas after the primary countercurrent adsorption is 150 to 1500 ppm; The mass content of volatile organic pollutants in the tail gas after the secondary countercurrent adsorption is 20 to 200 ppm.

8. The method for treating industrial tail gas according to claim 1, characterized in that: After the countercurrent adsorption, a β-cyclodextrin inclusion compound solid is obtained which settles at the bottom of the adsorption tower; The regeneration method of the β-cyclodextrin inclusion compound solid comprises the following steps: The β-cyclodextrin inclusion compound solid and the organic solvent are mixed and allowed to stand for solid-liquid separation to obtain regenerated β-cyclodextrin; The organic solvent is an alcohol solvent.

9. The method for treating industrial tail gas according to claim 8, characterized in that: The mass ratio of the β-cyclodextrin inclusion compound solid to the organic solvent is 1:2-3.

10. The method for treating industrial tail gas according to claim 8, characterized in that: The standing time is 4 to 6 hours.

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