Desulfurization equipment and desulfurization method for recovering sulfur element as acid solution

Abstract

The present invention discloses a desulfurization device and a desulfurization method for recovering sulfur element as an acid solution. The desulfurization device for recovering sulfur element as an acid solution comprises: a desulfurization unit, wherein the desulfurization unit utilizes an absorbent to react with at least sulfur dioxide in the gas to be treated to generate a soluble salt and discharge a reaction liquid containing the soluble salt; an oxidation unit, wherein the oxidation unit oxidizes the acid radical ions containing tetravalent sulfur in the reaction liquid into acid radical ions containing hexavalent sulfur; and a bipolar membrane unit, wherein the salt chamber of the bipolar membrane unit receives the reaction liquid treated by the oxidation unit and generates an alkaline solution in the alkaline chamber and an acid solution in the acid chamber respectively. By setting the oxidation unit, the sulfur element in the reaction liquid can be mainly present in the form of hydrogen sulfate and sulfate, which can not only reduce or even avoid the generation of gas in the acid chamber, but also the sulfur element is recovered in the form of sulfuric acid solution, which can significantly reduce energy consumption, extend the life of the equipment, and improve the utilization value of the sulfur element.

Description

Technical Field

[0001] The present invention relates to the technical field of desulfurization of sulfur-containing gases, and more particularly, to a desulfurization device and a desulfurization method for recovering sulfur elements as an acid solution. Background Art

[0002] The sulfide in sulfur-containing flue gas is mainly sulfur dioxide, and a small amount of sulfur dioxide (usually not exceeding 2% of the total volume of sulfur dioxide) may be oxidized to sulfur trioxide. Among the existing flue gas desulfurization technologies, the relatively mature method is the gypsum method, that is, a slurry made of limestone powder and water is used as an absorbent and pumped into a desulfurization tower to fully contact and mix with the sulfur-containing flue gas, so that sulfur dioxide in the flue gas reacts with calcium carbonate in the slurry and the air blown in from the lower part of the tower to generate calcium sulfate. After the calcium sulfate reaches a certain saturation, it crystallizes to form gypsum dihydrate. The gypsum slurry discharged from the desulfurization tower is concentrated and dehydrated to make its water content less than 10%, and then is sent to a gypsum storage bin for stacking by a conveyor.

[0003] The advantages of the gypsum method are that the desulfurization agent has rich sources, low price, and is fully utilized, the desulfurization efficiency can reach more than 95%, and there is no limit to the unit capacity. The disadvantages are that the system is relatively complex, occupies a large area, has a high investment, and generates a large amount of externally discharged residues. Summary of the Invention

[0004] The main object of the present invention is to provide a desulfurization device and a desulfurization method for recovering sulfur elements as an acid solution, so as to solve the problem of a large amount of externally discharged residues in the prior art.

[0005] To achieve the above object, according to one aspect of the present invention, a first desulfurization device for recovering sulfur elements as an acid solution is provided. The desulfurization device for recovering sulfur elements as an acid solution includes:

[0006] A desulfurization unit that uses an absorbent to react with at least sulfur dioxide in the gas to be treated to generate a soluble salt and discharges a reaction solution containing the soluble salt;

[0007] A bipolar membrane unit, the salt chamber of which receives the reaction solution and generates an alkaline solution in the alkaline chamber and an acid solution in the acid chamber respectively.

[0008] First of all, the desulfurization device of the present invention does not generate new solids, so there will be no technical problem of a large amount of externally discharged residues; compared with gypsum dihydrate, recovering sulfur elements in the form of an acid solution can improve the utilization value of sulfur elements. Secondly, the alkaline solution generated in the alkaline chamber of the bipolar membrane unit can be reused as an absorbent, so the entire device only needs to supplement an appropriate amount of absorbent at startup and can operate stably alone for a long time, with low operating costs.

[0009] To achieve the above object, according to one aspect of the present invention, a second desulfurization device for recovering sulfur element as an acid solution is provided. The desulfurization device for recovering sulfur element as an acid solution includes:

[0010] A desulfurization unit that uses an absorbent to react with at least sulfur dioxide in the gas to be treated to form a soluble salt and discharges a reaction solution containing the soluble salt;

[0011] An oxidation unit that oxidizes the acid radical ions containing tetravalent sulfur in the reaction solution into acid radical ions containing hexavalent sulfur;

[0012] A bipolar membrane unit, the salt chamber of the bipolar membrane unit receives the reaction solution treated by the oxidation unit and generates an alkaline solution in the alkaline chamber and an acid solution in the acid chamber respectively.

[0013] When the above first desulfurization device is in use, since the oxidation unit is not provided, the sulfur element in the reaction solution mainly exists in the form of bisulfite and sulfite. As a result, in addition to generating sulfurous acid in the acid chamber of the bipolar membrane unit, a large amount of sulfur dioxide gas will also be generated. On the one hand, these gases will reduce the solution conductivity, resulting in increased energy consumption. On the other hand, the process of bubble generation and rupture will impact the membrane, which may affect the membrane life. Therefore, by setting an oxidation unit, the sulfur element in the reaction solution can mainly exist in the form of bisulfate and sulfate, which can not only reduce or even avoid gas generation in the acid chamber, but also the sulfur element is recovered in the form of sulfuric acid solution, which can significantly reduce energy consumption, extend the equipment life and improve the utilization value of sulfur element.

[0014] As a further improvement of the above two desulfurization devices for recovering sulfur element as an acid solution, the oxidation unit includes a first oxidation unit, and the first oxidation unit includes an aeration device that introduces supplementary oxygen as an oxidant into the absorbent by stirring the absorbent; and / or,

[0015] The oxidation unit includes a second oxidation unit, and the second oxidation unit includes a first intermediate tank that receives the reaction solution discharged from the desulfurization unit and oxidizes the tetravalent sulfur in the reaction solution using the oxidant in the first intermediate tank.

[0016] Preferably, the first oxidation unit and the second oxidation unit are set simultaneously to maximize the reduction of the content of bisulfite and sulfite, thereby avoiding the generation of sulfur dioxide gas in the acid chamber.

[0017] As a further improvement of the above two desulfurization devices for recovering sulfur element as an acid solution,

[0018] It also includes a gas collection unit which is used to collect sulfur dioxide generated by the bipolar membrane. Thus, by setting up the gas collection unit, possible sulfur dioxide leakage can be avoided, and the collected sulfur dioxide has a high purity and can also be further utilized, such as being prepared into sulfuric acid.

[0019] It also includes a filtration unit which is used to intercept particulate matters in the reaction liquid. Thus, abrasion of the equipment pipeline caused by the particulate matters in the reaction liquid can be prevented.

[0020] As a further improvement of the above two kinds of desulfurization equipment for recovering sulfur elements as acid solutions, it also includes a first concentration unit which concentrates the reaction liquid and inputs the concentrated water obtained from the concentrated reaction liquid into the salt chamber of the bipolar membrane unit, and inputs the produced water obtained from the concentrated reaction liquid into the alkali chamber and acid chamber of the bipolar membrane unit. Thus, on the one hand, the energy consumption of the bipolar membrane unit can be reduced, and on the other hand, water supplementation from outside the system to the acid chamber and alkali chamber can be avoided or reduced, further reducing the operation cost.

[0021] As a further improvement of the above two kinds of desulfurization equipment for recovering sulfur elements as acid solutions, it also includes a pH adjustment unit which adjusts the pH of the reaction liquid before concentration.

[0022] As a further improvement of the above two kinds of desulfurization equipment for recovering sulfur elements as acid solutions, it also includes a second concentration unit which concentrates the product in the acid chamber of the bipolar membrane unit and inputs the produced water obtained from the concentration into the alkali chamber and acid chamber of the bipolar membrane unit. Thus, on the one hand, the volume of the final product can be reduced, saving transportation costs, and on the other hand, water supplementation from outside the system to the acid chamber and alkali chamber can be avoided or reduced, further reducing the operation cost; of course, it can also be determined whether to set up the second concentration unit and the concentration degree of the second concentration unit according to the product sales or usage mode.

[0023] To achieve the above purpose, according to one aspect of the present invention, there is provided a desulfurization method for recovering sulfur elements as acid solutions. The desulfurization method for recovering sulfur elements as acid solutions includes using any one of the above-mentioned desulfurization equipment for recovering sulfur elements as acid solutions; when starting up, an alkaline absorbent is added to the desulfurization unit as the initial absorbent, and during operation, a circulating liquid composed of the reaction liquid discharged from a part of the refluxed desulfurization unit, the alkali liquid generated in the alkali chamber of the bipolar membrane unit, and the electrolyzed liquid generated in the salt chamber is used as the new absorbent.

[0024] It has been verified that this desulfurization method can recover more than 95% of the sulfur elements in the gas to be treated in the form of acid, with a high recovery rate and high economic benefits.

[0025] As a further improvement of the above desulfurization method for recovering sulfur element as an acid solution, the absorbent is selected from any several of hydroxide solutions of alkali metals, hydroxide solutions of alkaline earth metals, carbonate reaction solutions of alkali metals, and carbonate reaction solutions of alkaline earth metals; preferably, the absorbent is selected from any several of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, and potassium carbonate solution.

[0026] As a further improvement of the above desulfurization method for recovering sulfur element as an acid solution, the pH of the circulating liquid is 5-8. Thus, it can be ensured that the reaction liquid contains less bisulfite and sulfite.

[0027] As a further improvement of the above desulfurization method for recovering sulfur element as an acid solution, it includes inputting supplementary oxygen gas as an oxidant into the desulfurization unit, and the supplementary oxygen gas is preferably air and / or oxygen; and / or, any several of hydrogen peroxide, ozone, sodium peroxide, and sodium persulfate are used to oxidize the tetravalent sulfur in the reaction liquid.

[0028] The following further describes the present invention in conjunction with the accompanying drawings and specific embodiments. The additional aspects and advantages of the present invention will be partly given in the following description, partly become obvious from the following description, or be understood through the practice of the present invention. Description of the Drawings

[0029] The drawings constituting a part of the present invention are used to assist in understanding the present invention. The content provided in the drawings and the related descriptions in the present invention can be used to explain the present invention, but do not constitute an improper limitation to the present invention. In the drawings:

[0030] Figure 1 It is a schematic structural diagram of the desulfurization equipment for recovering sulfur element as an acid solution in Example 1.

[0031] Figure 2 It is a working principle diagram of the bipolar membrane unit.

[0032] Figure 3 It is a schematic structural diagram of the desulfurization equipment for recovering sulfur element as an acid solution in Example 2.

[0033] Figure 4 It is a schematic structural diagram of the desulfurization equipment for recovering sulfur element as an acid solution in Example 3.

[0034] Figure 5 It is a schematic structural diagram of the desulfurization equipment for recovering sulfur element as an acid solution in Example 4.

[0035] Figure 6 It is a schematic structural diagram of the desulfurization equipment for recovering sulfur element as an acid solution in Example 5.

[0036] Figure 7Schematic structural diagram of the desulfurization equipment for recovering sulfur element as acid solution in Example 6.

[0037] The relevant markings in the above drawings are as follows:

[0038] 110 - spray pump, 120 - desulfurization tower, 210 - first oxidation unit, 220 - second oxidation unit, 230 - oxidant storage tank, 310 - bipolar membrane unit, 320 - gas collection unit, 400 - pH adjustment unit, 500 - filtration unit, 600 - first concentration unit, 700 - second concentration unit Detailed implementation manners

[0039] The present invention will be described clearly and completely below with reference to the accompanying drawings. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. Before describing the present invention with reference to the accompanying drawings, it should be particularly noted that:

[0040] The technical solutions and technical features provided in each part including the following description in the present invention can be combined with each other without conflict.

[0041] In addition, the embodiments of the present invention described below are generally only a part of the embodiments of the present invention, rather than all of the embodiments. Therefore, all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts should fall within the protection scope of the present invention.

[0042] Regarding the terms and units in the present invention. The terms "including", "having" and any variations thereof in the specification, claims and relevant parts of the present invention are intended to cover non-exclusive inclusion..

[0043] Example 1

[0044] Figure 1 Schematic structural diagram of the desulfurization equipment for recovering sulfur element as acid solution in this example.

[0045] As Figure 1 shown, the desulfurization equipment for recovering sulfur element as acid solution includes a desulfurization unit, a pH adjustment unit 400, a filtration unit 500, a first concentration unit 600 and a bipolar membrane unit 310.

[0046] The desulfurization unit uses an absorbent to react with at least sulfur dioxide in the gas to be treated to form a soluble salt and discharges the reaction solution containing the soluble salt; the desulfurization unit includes a spray pump 110 and a desulfurization tower 120, and the absorbent is sprayed into the desulfurization tower 120 from above through the spray pump 110 and then mixed and reacted with the gas to be treated entering from the middle of the desulfurization tower 120; a stirring device is provided at the bottom of the desulfurization tower 120.

[0047] The pH adjustment unit 400 includes a second intermediate tank that receives the reaction solution and adjusts the pH of the reaction solution using a portion of the acid solution generated in the acid chamber of the bipolar membrane unit 310. A stirring device is provided in the second intermediate tank.

[0048] The filtration unit 500 is used to intercept particulate matter in the reaction solution after being treated by the pH adjustment unit 400. The filtration unit 500 employs a tubular ultrafiltration membrane module with an interception rate of ≥90% for particulate matter with a particle size ≥0.1 mm.

[0049] The first concentration unit 600 employs a disc tube reverse osmosis membrane module. The first concentration unit 600 inputs the concentrated water obtained by concentrating the reaction solution into the salt chamber of the bipolar membrane unit 310, and inputs the produced water obtained by concentrating the reaction solution into the alkali chamber and the acid chamber of the bipolar membrane unit 310 at a volume ratio of 1:1.

[0050] The salt chamber of the bipolar membrane unit 310 receives the concentrated water from the first concentration unit 600, and the alkali chamber and the acid chamber of the bipolar membrane unit 310 receive the produced water from the first concentration unit 600. After power-on, according to Figure 2 the principle shown, an alkali solution is generated in the alkali chamber and an acid solution is generated in the acid chamber.

[0051] Example 2

[0052] Compared with Example 1, the difference of the desulfurization equipment for recovering sulfur element as an acid solution in this example is that: as Figure 3 shown, it further includes a second concentration unit 700. The second concentration unit 700 employs a spiral wound nanofiltration membrane module. The second concentration unit 700 concentrates the product in the acid chamber of the bipolar membrane unit 310 and inputs the produced water obtained by concentration into the alkali chamber and the acid chamber of the bipolar membrane unit 310 at a volume ratio of 1:1.

[0053] Example 3

[0054] Compared with Example 2, the difference of the desulfurization equipment for recovering sulfur element as an acid solution in this example is that: as Figure 4 shown, it further includes a gas collection unit 320. The gas collection unit 320 is used to collect the sulfur dioxide generated by the bipolar membrane.

[0055] Example 4

[0056] Figure 5 is a schematic structural diagram of the desulfurization equipment for recovering sulfur element as an acid solution in this example.

[0057] As Figure 5As shown in the figure, the desulfurization equipment for recovering sulfur elements as acid solution includes a desulfurization unit, an oxidation unit, a pH adjustment unit 400, a filtration unit 500, a first concentration unit 600, and a bipolar membrane unit 310.

[0058] The desulfurization unit uses an absorbent to react with at least sulfur dioxide in the gas to be treated to generate a soluble salt and discharges the reaction solution containing the soluble salt; the desulfurization unit includes a spray pump 110 and a desulfurization tower 120. The absorbent is sprayed into the desulfurization tower 120 from above through the spray pump 110, and then reacts with the gas to be treated entering from the middle of the desulfurization tower 120; a stirring device is provided at the bottom of the desulfurization tower 120.

[0059] Oxidation unit, the oxidation unit oxidizes the acid radical ions containing tetravalent sulfur in the reaction solution into acid radical ions containing hexavalent sulfur; the oxidation unit includes a first oxidation unit 210, and the first oxidation unit 210 includes an aeration device. The aeration device is arranged at the bottom of the desulfurization tower 120 and introduces supplementary oxygen as an oxidant into the absorbent by stirring the absorbent.

[0060] The pH adjustment unit 400 includes a second intermediate tank. The second intermediate tank receives the reaction solution from the first intermediate tank and adjusts the pH of the reaction solution by using part of the acid solution generated in the acid chamber of the bipolar membrane unit 310; a stirring device is provided in the second intermediate tank.

[0061] The filtration unit 500 uses a tubular ultrafiltration membrane module with an interception rate of particles with a particle size ≥ 0.1 mm ≥ 90%.

[0062] The first concentration unit 600 uses a disc tube reverse osmosis membrane module. The first concentration unit 600 inputs the concentrated water obtained by concentrating the reaction solution into the salt chamber of the bipolar membrane unit 310, and inputs the produced water obtained by concentrating the reaction solution into the alkali chamber and the acid chamber of the bipolar membrane unit 310 at a volume ratio of 1:1.

[0063] The salt chamber of the bipolar membrane unit 310 receives the concentrated water from the first concentration unit 600, and the alkali chamber and the acid chamber of the bipolar membrane unit 310 receive the produced water from the first concentration unit 600. After being energized, according to Figure 2 the principle shown in the figure, an alkali solution is generated in the alkali chamber and an acid solution is generated in the acid chamber.

[0064] Example 5

[0065] Compared with Example 4, the difference of the desulfurization equipment for recovering sulfur elements as acid solution in this example is that as Figure 6As shown, the oxidation unit further includes a second oxidation unit 220; the second oxidation unit 220 includes a first intermediate tank, which receives the reaction liquid discharged from the desulfurization unit and oxidizes the tetravalent sulfur in the reaction liquid by using the oxidant input into the first intermediate tank from the oxidant storage tank 230; a stirring device is provided in the first intermediate tank.

[0066] Example 6

[0067] Compared with Example 5, the difference of the desulfurization equipment with the recovered sulfur element being an acid solution in this example is that, as Figure 7 shown, it further includes a second concentration unit 700, the second concentration unit 700 adopts a spiral wound nanofiltration membrane module, and the second concentration unit 700 concentrates the acid chamber product of the bipolar membrane unit 310 and inputs the concentrated produced water into the alkali chamber and the acid chamber of the bipolar membrane unit 310 respectively according to a volume ratio of 1:1.

[0068] When using any one of the equipment in the above Examples 1-6 for desulfurization, only an alkaline absorbent needs to be added to the desulfurization unit as the initial absorbent at the start-up, and there is no need to add the alkaline absorbent during operation. The circulating liquid composed of the reaction liquid discharged from the partially refluxed desulfurization unit, the alkali liquid generated in the alkali chamber of the bipolar membrane unit 310, and the electrolyzed liquid generated in the salt chamber serves as the new absorbent.

[0069] Among them, the alkaline absorbent is selected from any several of the hydroxide solutions of alkali metals, the hydroxide solutions of alkaline earth metals, the carbonate reaction liquids of alkali metals, and the carbonate reaction liquids of alkaline earth metals.

[0070] Among them, the supplementary oxygen input into the desulfurization unit as the oxidant through the aeration device is oxygen; the first intermediate tank uses any several of hydrogen peroxide, ozone, sodium peroxide, and sodium persulfate to oxidize the tetravalent sulfur in the reaction liquid.

[0071] In the desulfurization tower 120, the absorbent reacts with sulfur dioxide and sulfur trioxide in the gas to be treated as follows:

[0072] SO 2 +H 2 O→H 2 SO 3 ;

[0073]

[0074] HSO 3 - +1 / 2O 2 →HSO 4 - ;

[0075] SO3 +H 2 O → H 2 SO 4 ; H 2 SO 4 → SO 4 2- +2H +

[0076] The distribution amounts of various acid radical ions can be obtained by calculating the distribution fraction diagram according to the acid ionization equilibrium constant and then querying according to the pH. After verification, when the pH of the circulating liquid is 5 - 8, preferably 5 - 6, the absorption amount of sulfur dioxide can be increased, and the contents of sulfite and bisulfite in the reaction liquid can also be reduced.

[0077] Figure 2 It is the working principle diagram of the bipolar membrane unit. As Figure 2 shown, by arranging the anion membrane and the cation membrane in a specific order, under the action of a direct current electric field, the positive metal ion M in the salt chamber + passes through the cation membrane and enters the alkali chamber to form an alkali solution with the hydroxide ions ionized at the bipolar membrane in the alkali chamber, and the negative acid radical ion X in the salt chamber - passes through the anion membrane and enters the acid chamber to form an acid solution with the hydrogen ions ionized at the bipolar membrane in the acid chamber.

[0078] Among them, the positive metal ion M + corresponds to the metal ion selected to form the alkaline absorbent, and the negative acid radical ions are sulfite, bisulfite, sulfate, and bisulfate. Among them, in the desulfurization equipment of Examples 5 - 6, the oxidation unit has both a first oxidation unit and a second oxidation unit. Therefore, most of the bisulfite is oxidized into bisulfate. Therefore, the main negative acid radical ions passing through the anion membrane are sulfate and bisulfate.

[0079] The above has described the relevant content of the present invention. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. Based on the above content of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Claims

1. Desulfurization equipment for recovering sulfur element as acid solution, characterized in that include: A desulfurization unit, wherein the desulfurization unit utilizes an absorbent to react with at least sulfur dioxide in the gas to be treated to generate soluble salts and discharges a reaction liquid containing the soluble salts; A bipolar membrane unit (310), wherein the bipolar membrane unit (310) comprises an acid chamber, a salt chamber and an alkali chamber; the salt chamber of the bipolar membrane unit (310) receives the reaction solution and generates an alkali solution in the alkali chamber and an acid solution in the acid chamber respectively; A first concentrating unit (600), wherein the first concentrating unit (600) concentrates the reaction solution and inputs the concentrated water obtained by concentrating the reaction solution into the salt chamber of the bipolar membrane unit (310) and inputs the produced water obtained by concentrating the reaction solution into the alkali chamber and the acid chamber of the bipolar membrane unit (310); The second concentrating unit (700) concentrates the acid chamber product of the bipolar membrane unit (310) and inputs the concentrated product water into the alkali chamber and the acid chamber of the bipolar membrane unit (310).

2. Desulfurization equipment for recovering sulfur element as acid solution, characterized in that include: A desulfurization unit, wherein the desulfurization unit utilizes an absorbent to react with at least sulfur dioxide in the gas to be treated to generate soluble salts and discharges a reaction liquid containing the soluble salts; An oxidation unit, wherein the oxidation unit oxidizes the acid radical ions containing tetravalent sulfur in the reaction solution into acid radical ions containing hexavalent sulfur; A bipolar membrane unit (310), wherein the bipolar membrane unit (310) comprises an acid chamber, a salt chamber and an alkali chamber; the salt chamber of the bipolar membrane unit (310) receives the reaction liquid treated by the oxidation unit and generates an alkali solution in the alkali chamber and an acid solution in the acid chamber respectively; A first concentrating unit (600), wherein the first concentrating unit (600) concentrates the reaction solution and inputs the concentrated water obtained by concentrating the reaction solution into the salt chamber of the bipolar membrane unit (310) and inputs the produced water obtained by concentrating the reaction solution into the alkali chamber and the acid chamber of the bipolar membrane unit (310); The second concentrating unit (700) concentrates the acid chamber product of the bipolar membrane unit (310) and inputs the concentrated product water into the alkali chamber and the acid chamber of the bipolar membrane unit (310).

3. The desulfurization equipment for recovering sulfur element as acid solution according to claim 2, characterized in that: The oxidation unit comprises a first oxidation unit (210), wherein the first oxidation unit (210) comprises an aeration device, wherein the aeration device introduces supplementary oxygen as an oxidant into the absorbent by stirring the absorbent; and / or, The oxidation unit comprises a second oxidation unit (220), wherein the second oxidation unit (220) comprises a first intermediate tank, wherein the first intermediate tank receives the reaction liquid discharged from the desulfurization unit and utilizes the oxidant in the first intermediate tank to oxidize the tetravalent sulfur in the reaction liquid.

4. The desulfurization equipment for recovering sulfur element as acid solution according to any one of claims 1 to 3, characterized in that: It also includes a gas collection unit (320), wherein the gas collection unit (320) is used to collect sulfur dioxide generated by the bipolar membrane; It also includes a filtering unit (500), and the filtering unit (500) is used to intercept particulate matter in the reaction liquid.

5. The desulfurization equipment for recovering sulfur element as acid solution according to any one of claims 1 to 3, characterized in that: The method further comprises a pH adjustment unit (400) for adjusting the pH of the reaction solution before concentration.

6. A desulfurization method for recovering sulfur as an acid solution, comprising: using the desulfurization equipment for recovering sulfur as an acid solution as claimed in any one of claims 1 to 5; adding an alkaline absorbent as an initial absorbent to the desulfurization unit during start-up; and using a circulating liquid composed of a reaction liquid discharged from the desulfurization unit by partial reflux, an alkaline liquid produced in an alkaline chamber of a bipolar membrane unit (310), and a post-electrolysis liquid produced in a salt chamber as a new absorbent during operation.

7. The desulfurization method for recovering sulfur element as acid solution according to claim 6, characterized in that: The alkaline absorbent is selected from any of alkali metal hydroxide solutions, alkaline earth metal hydroxide solutions, alkali metal carbonic acid reaction solutions and alkaline earth metal carbonic acid reaction solutions; and / or the pH of the circulating liquid is 5-8.

8. The desulfurization method for recovering sulfur element as acid solution according to claim 6, characterized in that: The method comprises inputting supplementary oxygen as an oxidant into the desulfurization unit, wherein the supplementary oxygen is preferably air and / or oxygen; and / or, using any of hydrogen peroxide, ozone, sodium peroxide, and sodium persulfate to oxidize the tetravalent sulfur in the reaction solution.

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