TWI838069B - Desulfurization method for sulfur-containing tail gas - Google Patents

Abstract

A method for desulfurizing sulfur-containing tail gas is applicable to treating the sulfur-containing tail gas containing hydrogen sulfide and sulfur dioxide, and comprises the following steps: (a) cooling the sulfur-containing tail gas to reduce hydrogen sulfide and sulfur dioxide in the sulfur-containing tail gas, thereby obtaining a gas mixture containing hydrogen sulfide and sulfur dioxide with a concentration of less than 20 ppm; (b) providing an alkaline treatment liquid, wherein the alkaline treatment liquid comprises a used alkaline solution recovered from a desulfurization device used for scrubbing coke furnace gas; and (c) contacting the gas mixture with the alkaline treatment liquid in a wet scrubbing device, and allowing the hydrogen sulfide in the gas mixture to be absorbed by the alkaline treatment liquid, thereby obtaining treated gas. The present invention can remove hydrogen sulfide in sulfur-containing tail gas through the combination of steps (a) to (c) and has the advantage of saving subsequent treatment costs.

Description

Desulfurization method for sulfur-containing tail gas

The present invention relates to a gas separation method, in particular to a desulfurization method for sulfur-containing tail gas.

The existing coking process often produces crude coke oven gas containing acidic substances such as hydrogen sulfide, hydrogen cyanide, carbon dioxide and ammonia, i.e., unpurified coke oven gas. Coke oven gas (COG) is a combustible gas, so it can be used as a fuel. In order to effectively utilize the coke oven gas, the crude coke oven gas is usually scrubbed to remove the acidic substances and ammonia in the crude coke oven gas to obtain coke oven gas with high purity.

Referring to FIG. 1 , the crude coke furnace gas is scrubbed to remove acidic substances by, for example, using an alkaline solution in a desulfurization device 91 to remove acidic substances in the crude coke furnace gas to produce a used alkaline solution containing acidic substances, and the used alkaline solution is recycled and processed to produce a recycled alkaline solution and sulfur-containing exhaust gas. The recycled alkaline solution can be transported back to the desulfurization device 91 for use as an alkaline solution. The sulfur-containing exhaust gas is introduced into a sulfur recovery device 92 for sulfur recovery processing to obtain sulfur, and at the same time, sulfur-containing tail gas containing hydrogen sulfide and sulfur dioxide is produced. In order to prevent the sulfur-containing tail gas from being directly discharged into the atmosphere, the sulfur-containing tail gas is usually mixed with the next batch of crude coke gas to obtain a mixture, and then the mixture is passed into the desulfurization device 91 for treatment. However, due to the high concentration of hydrogen sulfide and sulfur dioxide in the sulfur-containing tail gas, when the alkaline solution is used to wash the mixture without changing the amount of the alkaline solution, the total content of the acidic components present in the washing process will increase, that is, the original acidic substances in the crude coke gas plus the hydrogen sulfide and sulfur dioxide in the sulfur-containing tail gas, which increases the washing load of the desulfurization device 91, and thus it is impossible to effectively obtain high-purity coke gas in the next batch of treatment.

Based on the above, in order to obtain high-purity coke furnace gas for the next batch of processing, although the above problem can be improved by greatly increasing the amount of alkaline solution used, the increase in the amount of alkaline solution used will instead increase the processing cost.

Therefore, the purpose of the present invention is to provide a method for desulfurizing sulfur-containing tail gas which can reduce costs.

Therefore, the desulfurization method of sulfur-containing tail gas of the present invention is applicable to treating a sulfur-containing tail gas containing hydrogen sulfide and sulfur dioxide. The desulfurization method of sulfur-containing tail gas comprises step (a), step (b) and step (c).

The step (a) is to cool the sulfur-containing tail gas to reduce the hydrogen sulfide content and sulfur dioxide content in the sulfur-containing tail gas, thereby obtaining a gas mixture containing hydrogen sulfide and sulfur dioxide with a concentration of less than 20 ppm, wherein the hydrogen sulfide content in the gas mixture is less than the hydrogen sulfide content in the sulfur-containing tail gas.

The step (b) is to provide an alkaline treatment solution, wherein the alkaline treatment solution comprises a used alkaline solution recovered from a desulfurization device, and the desulfurization device is used to scrub a mixture containing coke furnace gas with an alkaline solution containing sodium hydroxide, and the used alkaline solution comprises sodium hydroxide.

The step (c) is to make the gas mixture contact with the alkaline treatment liquid in a wet scrubber, and make the hydrogen sulfide in the gas mixture be absorbed by the alkaline treatment liquid to obtain treated gas.

The effect of the present invention is that: through the combination of the steps (a) to (c), the present invention can effectively remove hydrogen sulfide in the sulfur-containing tail gas, so that the hydrogen sulfide content in the treated gas is less than the hydrogen sulfide content in the sulfur-containing tail gas.

On the other hand, when the treated gas is subsequently mixed with the next batch of crude coke furnace gas in order to prevent the treated gas from being directly discharged into the atmosphere, the low content of hydrogen sulfide in the treated gas can avoid the problem of excessive acidic components in the mixture obtained by mixing the treated gas and the crude coke furnace gas. Therefore, through the desulfurization method of sulfur-containing tail gas of the present invention, when the mixture containing crude coke furnace gas and treated gas is subsequently washed, coke furnace gas with higher purity can be obtained while the amount of alkaline solution used remains unchanged, or the coke furnace gas can be obtained with a smaller amount of alkaline solution used while the required purity of the coke furnace gas remains unchanged. Therefore, the present invention has the advantage of being able to save subsequent processing costs.

Referring to FIG. 2 , the desulfurization method of sulfur-containing tail gas of the present invention is applicable to treating a sulfur-containing tail gas containing hydrogen sulfide and sulfur dioxide. The source of the sulfur-containing tail gas is, for example but not limited to, the sulfur-containing tail gas discharged from a sulfur recovery device 2. The sulfur recovery device 2 is used to receive the sulfur-containing waste gas and recover the sulfur-containing waste gas, thereby recovering sulfur from the sulfur-containing waste gas and discharging the sulfur-containing tail gas.

The desulfurization method of sulfur-containing tail gas comprises a step (a), a step (b) and a step (c).

The step (a) is to cool the sulfur-containing tail gas to reduce the hydrogen sulfide content and sulfur dioxide content in the sulfur-containing tail gas, thereby obtaining a gas mixture containing hydrogen sulfide and sulfur dioxide with a concentration of less than 20 ppm, wherein the hydrogen sulfide content in the gas mixture is less than the hydrogen sulfide content in the sulfur-containing tail gas.

The step (b) is to provide an alkaline treatment liquid, wherein the alkaline treatment liquid comprises a used alkaline solution recovered from a desulfurization device 1, and the desulfurization device 1 is used to scrub a mixture containing coke furnace gas with an alkaline solution containing sodium hydroxide, and the used alkaline solution comprises sodium hydroxide.

The step (c) is to make the gas mixture contact with the alkaline treatment liquid in a wet scrubber 3, and make the hydrogen sulfide in the gas mixture be absorbed by the alkaline treatment liquid to obtain treated gas.

The present invention is described in detail below.

《Step (a)》

The sulfur-containing tail gas generally contains water vapor in addition to hydrogen sulfide and sulfur dioxide. The cooling treatment is used to reduce the temperature of the sulfur-containing tail gas so that the water vapor in the sulfur-containing tail gas condenses into water during the cooling process of the sulfur-containing tail gas, and at the same time, part of the hydrogen sulfide and part of the sulfur dioxide are dissolved in the water, thereby reducing the hydrogen sulfide content and sulfur dioxide content in the sulfur-containing tail gas, and then obtaining the gas mixture and the acidic condensate containing sulfurous acid and sulfuric acid.

There is no particular limitation on the method of cooling treatment, as long as the temperature of the sulfur-containing tail gas can be reduced and the content of hydrogen sulfide and sulfur dioxide in the sulfur-containing tail gas can be reduced, the present invention is applicable. In some embodiments of the present invention, the cooling treatment is to cool the sulfur-containing tail gas using cooling water at room temperature (25° C.) to reduce the temperature of the sulfur-containing tail gas to room temperature (25° C.).

It should be noted that, since the temperature of the sulfur-containing tail gas is lowered by the cooling treatment in the step (a), the water vapor in the sulfur-containing tail gas is condensed into water, and then part of the hydrogen sulfide and part of the sulfur dioxide are dissolved in the water to form an acidic condensate, thereby reducing the content of hydrogen sulfide and sulfur dioxide in the sulfur-containing tail gas and obtaining the gas mixture. Therefore, in the step (c), hydrogen sulfide can be effectively absorbed from the gas mixture while using a small amount of the alkaline treatment liquid, thereby having a good hydrogen sulfide absorption effect.

《Step (b)》

The desulfurization device 1 is used to receive the crude coke furnace gas containing acidic substances and ammonia, and use the alkaline solution to wash the crude coke furnace gas to reduce the content of acidic substances such as hydrogen sulfide, hydrogen cyanide, carbon dioxide, etc. in the crude coke furnace gas, thereby obtaining high-purity coke furnace gas, which is beneficial to the subsequent application of the coke furnace gas as fuel.

In addition, during the process of washing the crude coke furnace gas with the alkaline solution, the alkaline solution absorbs acidic substances such as hydrogen sulfide, hydrogen cyanide, carbon dioxide, etc. Therefore, the used alkaline solution recovered from the desulfurization device 1 includes, in addition to sodium hydroxide, acidic substances such as hydrogen sulfide, hydrogen cyanide, carbon dioxide, etc. or products of the reaction between the above acidic substances and sodium hydroxide.

It should be noted that, in addition to being able to discharge the used alkaline solution, part of the used alkaline solution will be recycled and processed in the desulfurization device 1 to produce recycled alkaline solution and sulfur-containing exhaust gas. Therefore, the desulfurization device 1 will also discharge sulfur-containing exhaust gas containing hydrogen sulfide. The sulfur-containing exhaust gas can be further transported to the sulfur recovery device 2 as described above for recycling and processing, thereby being converted into sulfur and sulfur-containing tail gas.

In some embodiments of the present invention, in order to make the hydrogen sulfide in the gas mixture be more effectively absorbed by the alkaline treatment liquid to achieve a better hydrogen sulfide removal effect, the alkaline treatment liquid further comprises an alkaline adjusting agent. The alkaline adjusting agent is used to adjust the pH value of the alkaline treatment liquid, so that the alkaline treatment liquid has a better absorption effect on hydrogen sulfide. The type of the alkaline adjusting agent is not particularly limited, as long as the reagent can give the alkaline treatment liquid a better hydrogen sulfide absorption effect, it is applicable to the present invention. In some embodiments of the present invention, the alkaline adjusting agent is a sodium hydroxide aqueous solution containing sodium hydroxide at a concentration of 0.5wt%. In some embodiments of the present invention, the volume ratio of the alkaline solution to the alkaline adjuster is in the range of 0.1 to 9.

《Step (c)》

The wet scrubbing device 3 includes a first injection port for allowing the gas mixture to pass through, a second injection port arranged vertically opposite to the first injection port and used for allowing the alkaline treatment liquid to pass through, and a packed bed arranged between the first injection port and the second injection port. The packed bed is used to enable the gas mixture and the alkaline treatment liquid to effectively contact each other, thereby effectively removing hydrogen sulfide in the gas mixture through the alkaline treatment liquid. In some embodiments of the present invention, the first injection port is formed at the lower part of the wet scrubber 3 so that the gas mixture flows from bottom to top after entering the wet scrubber 3 through the first injection port; and the second injection port is formed at the upper part of the wet scrubber 3 so that the alkaline treatment solution flows from top to bottom on the gas mixture after entering the wet scrubber 3 through the second injection port.

In some embodiments of the present invention, under the condition of having a good hydrogen sulfide removal effect, in order to further take into account the operating cost when removing hydrogen sulfide from the gas mixture, the flow ratio of the gas mixture to the alkaline treatment liquid ranges from 33 to 100.

The number of the packed beds is not limited to one, but may be multiple, and the number of packed beds can be adjusted arbitrarily according to the use requirements. In some embodiments of the present invention, in order to further improve the removal effect of hydrogen sulfide, the height of the packed bed ranges from 37 cm to 148 cm.

In some embodiments of the present invention, in step (c), after the gas mixture contacts the alkaline treatment liquid, part of the hydrogen sulfide in the gas mixture is absorbed by the alkaline treatment liquid, so the treated gas obtained in step (c) contains hydrogen sulfide, and the hydrogen sulfide in the treated gas comes from the hydrogen sulfide in the gas mixture that is not absorbed by the alkaline treatment liquid. Since the hydrogen sulfide in the treated gas comes from the hydrogen sulfide in the gas mixture that is not absorbed by the alkaline treatment liquid, the concentration of hydrogen sulfide in the treated gas is lower than the concentration of hydrogen sulfide in the gas mixture.

The present invention will be further described with respect to the following embodiments, but it should be understood that the embodiments are only for illustrative purposes and should not be interpreted as limitations on the implementation of the present invention.

[Example 1]

(a) Cooling sulfur-containing tail gas discharged from a sulfur recovery device 2 and containing hydrogen sulfide, sulfur dioxide and water vapor at a temperature of 140° C. to reduce the temperature of the sulfur-containing tail gas to room temperature (25° C.), thereby condensing the water vapor into water, and dissolving part of the hydrogen sulfide and part of the sulfur dioxide in the water, to obtain a gas mixture containing hydrogen sulfide at a concentration of 13222 ppm and sulfur dioxide at a concentration of 6 ppm and an acidic condensate containing sulfurous acid and sulfuric acid. The sulfur-containing tail gas contains hydrogen sulfide at a concentration of 4000 ppm to 6000 ppm and sulfur dioxide at a concentration of 500 ppm to 1200 ppm. The concentrations of hydrogen sulfide and sulfur dioxide in the sulfur-containing tail gas were measured at 140° C., and the concentrations of hydrogen sulfide and sulfur dioxide in the gas mixture were measured at 25° C.

(b) recovering a used alkaline solution from a desulfurization device 1 for scrubbing a mixture containing coke furnace gas with an alkaline solution containing sodium hydroxide, and using the used alkaline solution as an alkaline treatment solution, wherein the used alkaline solution includes sodium hydroxide.

(c) the gas mixture is introduced into the wet scrubber 3 through a first injection port formed at the lower portion of the wet scrubber 3, and the alkaline treatment liquid is introduced into the wet scrubber 3 through a second injection port formed at the upper portion of the wet scrubber 3, so that the gas mixture in the wet scrubber 3 flows from bottom to top and contacts the alkaline treatment liquid eluted from top to bottom, so that hydrogen sulfide in the gas mixture is absorbed by the alkaline treatment liquid, and a treated gas containing hydrogen sulfide at a concentration of 5468 ppm is obtained. The gas mixture is passed into the wet scrubber 3 at a flow rate of 40 L/min, the alkaline treatment liquid is passed into the wet scrubber 3 at a flow rate of 0.4 L/min, the flow ratio of the gas mixture to the alkaline treatment liquid is 100, and the height of the packed bed is 37 cm. In addition, according to the concentration of hydrogen sulfide in the treated gas, the removal rate of hydrogen sulfide in the gas mixture is 58.6%.

[Examples 2 to 9]

Examples 2 to 9 treat sulfur-containing tail gas in a manner similar to Example 1, except that the height of the packed bed and the flow rate of the alkaline treatment solution are changed. The results are shown in Table 1.

[Examples 10 to 13]

Examples 10 to 13 treat sulfur-containing tail gas in a manner similar to Example 1, except that: in step (a), the gas mixture contains hydrogen sulfide with a concentration of 14000 ppm and sulfur dioxide with a concentration of 6 ppm; in step (c), the flow rate of the alkaline treatment liquid is 1.2 L/min, and the flow rate ratio of the gas mixture to the alkaline treatment liquid is 33.3, wherein the heights of the packed beds of Examples 10 to 13 are 37 cm, 74 cm, 111 cm and 148 cm, respectively.

[Examples 14 to 25]

Examples 14 to 25 treat sulfur-containing tail gas in a manner similar to Example 1, except that: in step (a), the gas mixture contains hydrogen sulfide at a concentration of 14000 ppm and sulfur dioxide at a concentration of 6 ppm; in step (b), the used alkaline solution is mixed with an aqueous sodium hydroxide solution containing 0.5 wt % sodium hydroxide (as an alkaline adjuster) to obtain an alkaline treatment solution; in step (c), the flow rate of the alkaline treatment solution is 1.2 L/min, and the flow rate ratio of the gas mixture to the alkaline treatment solution is 33.3, wherein In Examples 14 to 17, the volume ratio of the alkaline solution to the alkaline adjuster was 9, and the heights of the packed beds were 37 cm, 74 cm, 111 cm and 148 cm, respectively; in Examples 18 to 21, the volume ratio of the alkaline solution to the alkaline adjuster was 1, and the heights of the packed beds were 37 cm, 74 cm, 111 cm and 148 cm, respectively; in Examples 22 to 25, the volume ratio of the alkaline solution to the alkaline adjuster was 0.11, and the heights of the packed beds were 37 cm, 74 cm, 111 cm and 148 cm, respectively.

[Example 26]

Example 26 treats sulfur-containing tail gas in a manner similar to Example 1, except that: in step (a), the gas mixture contains hydrogen sulfide with a concentration of 13800 ppm and sulfur dioxide with a concentration of 6 ppm; in step (c), the flow rate of the alkaline treatment liquid is 1.2 L/min, the flow rate ratio of the gas mixture to the alkaline treatment liquid is 33.3, the volume ratio of the alkaline solution used to the alkaline adjuster is 0.11, and the packed bed is 111 cm.

[Evaluation Items]

The following is explained using Example 1 as an example, and the remaining examples are carried out in the same manner.

Hydrogen sulfide removal rate: The gas mixture and the treated gas are measured using a laser gas analyzer (brand: SERVOMEX) to obtain the concentration of hydrogen sulfide in the gas mixture and the concentration of hydrogen sulfide in the treated gas, and the removal rate of hydrogen sulfide in the gas mixture is calculated based on the concentration of hydrogen sulfide in the gas mixture and the treated gas. Hydrogen sulfide removal rate (unit: %) = (hydrogen sulfide concentration in the gas mixture - hydrogen sulfide concentration in the treated gas) / hydrogen sulfide concentration in the gas mixture × 100%.

Table 1 Embodiment 1 2 3 4 5 6 7 8 9 Hydrogen sulfide concentration in gas mixture (ppm) 13222 13222 13222 13222 13222 13222 13222 13222 13222 Flow rate of gas mixture (L/min) 40 40 40 40 40 40 40 40 40 Alkaline treatment liquid flow rate (L/min) 0.4 0.4 0.4 0.8 0.8 0.8 1.2 1.2 1.2 Flow ratio of gas mixture to alkaline treatment liquid 100 100 100 50 50 50 33.3 33.3 33.3 Height of packed bed (cm) 37 74 111 37 74 111 37 74 111 Hydrogen sulfide concentration in treated gas (ppm) 5468 5062 3387 5325 4506 2862 4981 3931 2093 Hydrogen sulfide removal rate (%) 58.6 61.7 74.4 59.7 65.9 78.4 62.3 70.3 84.2

Table 2 Embodiment 10 11 12 13 14 15 16 17 Hydrogen sulfide concentration in gas mixture (ppm) 14000 14000 14000 14000 14000 14000 14000 14000 Flow rate of gas mixture (L/min) 40 40 40 40 40 40 40 40 Alkaline treatment solution Alkaline solution used O O O O O O O O Alkaline regulator X X X X O O O O Volume ratio of alkaline solution to alkaline regulator used -- -- -- -- 9 9 9 9 Flow rate (L/min) 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 Flow ratio of gas mixture to alkaline treatment liquid 33.3 33.3 33.3 33.3 33.3 33.3 33.3 33.3 Height of packed bed (cm) 37 74 111 148 37 74 111 148 Hydrogen sulfide concentration in treated gas (ppm) 4806 3289 2900 2812 4556 2991 2630 2578 Hydrogen sulfide removal rate (%) 65.7 76.5 79.3 79.9 67.5 78.6 81.2 81.6 Note: “O” indicates used; “X” indicates not used.

table 3 Embodiment 18 19 20 twenty one twenty two twenty three twenty four 25 26 Hydrogen sulfide concentration in gas mixture (ppm) 14000 14000 14000 14000 14000 14000 14000 14000 13800 Flow rate of gas mixture (L/min) 40 40 40 40 40 40 40 40 40 Alkaline treatment solution Alkaline solution used O O O O O O O O O Alkaline regulator O O O O O O O O O Volume ratio of alkaline solution to alkaline regulator used 1 1 1 1 0.11 0.11 0.11 0.11 0.11 Flow rate (L/min) 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 Flow ratio of gas mixture to alkaline treatment liquid 33.3 33.3 33.3 33.3 33.3 33.3 33.3 33.3 33.3 Height of packed bed (cm) 37 74 111 148 37 74 111 148 111 Hydrogen sulfide concentration in treated gas (ppm) 3304 1487 1036 930 2792 860 351 176 83 Removal rate of hydrogen sulfide (%) 76.4 89.4 92.6 93.4 80.1 93.9 97.5 98.7 99.4 Note: “O” means in use.

Referring to Table 1, the desulfurization methods of sulfur-containing tail gas of Examples 1 to 9 have hydrogen sulfide removal rates of 58.6% to 84.2%, which indicates that Examples 1 to 9 can indeed effectively remove hydrogen sulfide from the sulfur-containing tail gas.

Referring to Tables 2 to 3, it can be seen from the results of the hydrogen sulfide removal rate of Examples 10 to 26 that, regardless of whether an alkaline regulator is added to the alkaline treatment solution, Examples 10 to 26 can effectively remove hydrogen sulfide from the sulfur-containing tail gas and have a hydrogen sulfide removal rate of 65.7% to 99.4%. In addition, under the same packed bed height, when the volume ratio of the used alkaline solution to the alkaline regulator in the alkaline treatment solution is smaller, that is, the more the alkaline regulator is used, the better the hydrogen sulfide removal effect is. This means that in the face of different hydrogen sulfide removal rate requirements, when the alkaline treatment solution contains the used alkaline solution, the present invention can indeed choose whether to add an alkaline regulator according to different requirements.

In summary, the desulfurization method of sulfur-containing tail gas of the present invention can effectively remove hydrogen sulfide in the sulfur-containing tail gas through the combination of steps (a) to (c). Therefore, the hydrogen sulfide content in the treated gas is less than the hydrogen sulfide content in the sulfur-containing tail gas.

On the other hand, when the treated gas is subsequently mixed with the next batch of crude coke furnace gas in order to prevent the treated gas from being directly discharged into the atmosphere, since the hydrogen sulfide content in the treated gas is low, under the condition that the content of acidic substances in the crude coke furnace gas introduced into the desulfurization device 1 remains unchanged, the total content of acidic components in the mixture obtained by mixing the treated gas and the crude coke furnace gas is relatively smaller than the total content of acidic components in the mixture containing sulfur-containing tail gas and crude coke furnace gas, so the amount of hydrogen sulfide in the treated gas can be avoided. The acidic components in the mixture obtained by mixing the gas with the crude coke furnace gas are too high. Therefore, through the desulfurization method of sulfur-containing tail gas of the present invention, when the mixture containing the crude coke furnace gas and the treated gas is subsequently washed, coke furnace gas with higher purity can be obtained while the amount of alkaline solution used remains unchanged, or the coke furnace gas can be obtained with a smaller amount of alkaline solution used while the required purity of the coke furnace gas remains unchanged. Therefore, the present invention has the advantage of being able to save subsequent processing costs, and can indeed achieve the purpose of the present invention.

However, the above is only an embodiment of the present invention and should not be used to limit the scope of implementation of the present invention. All simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the patent specification are still within the scope of the present patent.

1: Desulfurization device

2: Sulfur recovery device

3: Wet washing device

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: FIG. 1 is a flow chart illustrating the existing treatment method of crude coke furnace gas, sulfur-containing waste gas and sulfur-containing tail gas; and FIG. 2 is a flow chart illustrating an embodiment of the desulfurization method of sulfur-containing tail gas of the present invention.

1: Desulfurization device

2: Sulfur recovery device

3: Wet washing device

Claims (6)

A method for desulfurizing sulfur-containing tail gas is applicable to treating a sulfur-containing tail gas containing hydrogen sulfide and sulfur dioxide. The method for desulfurizing sulfur-containing tail gas comprises the following steps: (a) cooling the sulfur-containing tail gas to reduce the hydrogen sulfide content and sulfur dioxide content in the sulfur-containing tail gas, thereby obtaining a gas mixture containing hydrogen sulfide and sulfur dioxide with a concentration of less than 20 ppm, wherein the hydrogen sulfide content in the gas mixture is less than the hydrogen sulfide content in the sulfur-containing tail gas; (b) providing an alkaline treatment solution, wherein the alkaline treatment solution The method comprises: (a) recovering a used alkaline solution from a desulfurization device, wherein the desulfurization device is used to scrub a mixture containing coke furnace gas with an alkaline solution containing sodium hydroxide, wherein the used alkaline solution includes sodium hydroxide; and (c) contacting the gas mixture with the alkaline treatment liquid in a wet scrubbing device, and allowing the hydrogen sulfide in the gas mixture to be absorbed by the alkaline treatment liquid to obtain treated gas, wherein the flow ratio of the gas mixture to the alkaline treatment liquid ranges from 33 to 100. The desulfurization method of sulfur-containing tail gas as described in claim 1, wherein the wet scrubber comprises a first injection port for the gas mixture to pass through, a second injection port disposed vertically opposite to the first injection port and for the alkaline treatment liquid to pass through, and at least one packed bed disposed between the first injection port and the second injection port, and the height of the at least one packed bed ranges from 37 cm to 148 cm. The desulfurization method of sulfur-containing tail gas as described in claim 1, wherein, in the wet scrubbing device, the gas mixture flows from bottom to top, and the alkaline treatment liquid is poured on the gas mixture from top to bottom. The desulfurization method of sulfur-containing tail gas as described in claim 1, wherein the alkaline treatment liquid also contains an alkaline regulator. The desulfurization method of sulfur-containing tail gas as described in claim 4, wherein the alkaline regulator is an aqueous solution of sodium hydroxide. A method for desulfurizing sulfur-containing tail gas as described in claim 4, wherein the volume ratio of the used alkaline solution to the alkaline regulator ranges from 0.1 to 9.

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