Treatment method for increasing concentration of sulfuric acid in low-sulfur flue gas in wet-process acid preparation process

Abstract

The invention discloses a treatment method for increasing the concentration of sulfuric acid in low-sulfur flue gas in the wet-process acid making process, and particularly relates to the technical field of concentration of sulfuric acid produced by low-sulfur flue gas in the wet-process acid making process, and the treatment method for increasing the concentration of sulfuric acid in low-sulfur flue gas in the wet-process acid making process comprises the following steps: washing sulfur dioxide-containing process gas in a power wave washer to remove moisture; one part of the washing liquid flowing down enters a sulfur degasser system to desorb sulfur dioxide gas, and is mixed with the washed process gas to enter a high-voltage electrostatic demister, so that moisture entrained in the process gas is further removed under the action of a high-voltage electric field in the high-voltage electrostatic demister; water in flue gas can be separated by adopting the dynamic wave scrubber and the high-voltage electrostatic demister, so that the concentration of sulfur dioxide in process gas is relatively improved, scrubbing liquid is desorbed through the sulfur degasser system, sulfur dioxide gas is generated, the concentration of sulfur dioxide is further improved, and the concentration of a sulfuric acid product is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of sulfuric acid concentration improvement from low-sulfur flue gas in wet sulfuric acid production, and specifically to a treatment method for improving the sulfuric acid concentration of low-sulfur flue gas during the wet sulfuric acid production process. Background Technique

[0002] For the method of dealing with unqualified sulfuric acid concentration in low-sulfur flue gas during the wet sulfuric acid production process, there are the following adjustment methods: 1. Increase the sulfur content in the flue gas. By adding sulfur-containing substances such as sulfur and hydrogen sulfide to the flue gas to increase the sulfur content in the flue gas. Although the operation is simple, it requires additional investment in sulfur-containing substances, increasing the production cost. It also requires modification of equipment such as incinerators, and the addition amount needs to be precisely controlled. Otherwise, it may cause other problems, such as excessive sulfur dioxide emissions.

[0003] 2. Adjust the reaction temperature and pressure. According to the reaction principle, appropriately adjust the reaction temperature and pressure during the wet sulfuric acid production process to make the direction of sulfur dioxide conversion to sulfur trioxide and the reaction of trioxide with water to form sulfuric acid more favorable for the formation of sulfuric acid. This measure requires in-depth understanding and precise control of the process. The adjustment range of temperature and pressure is limited. Excessive adjustment may affect the equipment life or cause an increase in other side reactions, and it is too dependent on the ability of personnel and cannot effectively achieve the goal.

[0004] Common sulfuric acid concentration improvement methods include distillation method, concentration crystallization method, membrane separation method, extraction method, etc.

[0005] Distillation method: It utilizes the boiling point difference between sulfuric acid and water to achieve the improvement of sulfuric acid concentration. It has high energy consumption and requires a large amount of heat energy to heat the solution. Moreover, gases such as sulfur dioxide are produced during the heating process, which will not only reduce the sulfuric acid recovery rate but also cause environmental pollution. The equipment investment and operation cost are both high.

[0006] Concentration crystallization method: By cooling or evaporating the solvent, sulfuric acid crystallizes out. After being separated from the mother liquor and redissolved, higher-concentration sulfuric acid is obtained. This method requires precise control of various conditions, the operation process is complex, a part of sulfuric acid is lost during the crystallization and separation process, resulting in a low recovery rate, and the equipment is prone to problems such as scaling and blockage, affecting production efficiency and equipment life.

[0007] Membrane separation method: Utilize the selective permeability of the semi-permeable membrane to sulfuric acid and water. Driven by the pressure difference, water permeates through the membrane while sulfuric acid is retained, thereby achieving sulfuric acid concentration improvement. For such methods, the cost of the membrane is high, and the service life is limited. The membrane module needs to be replaced regularly, increasing the operation cost; the membrane flux is limited, making it difficult to meet large-scale production; the water quality requirements for the feed sulfuric acid solution are high, and strict pretreatment is required.

[0008] 4. Extraction method: Select a suitable extractant to increase the sulfuric acid concentration through extraction and separation. There are many limiting factors in the selection of extractants for this type of method. The extractant needs to be replenished regularly, and the extraction equipment and operations are relatively complex. Various extraction conditions need to be strictly controlled to ensure the roughing effect and product quality. Therefore, we propose a treatment method for increasing the sulfuric acid concentration of low-sulfur flue gas during the wet sulfuric acid production process and a method for solving the above problems. Summary of the Invention

[0009] The purpose of the present invention is to provide a treatment method for increasing the sulfuric acid concentration of low-sulfur flue gas during the wet sulfuric acid production process and a method to solve the problems raised in the above background technology.

[0010] To achieve the above object, the present invention provides the following technical solution: A treatment method for increasing the sulfuric acid concentration of low-sulfur flue gas during the wet sulfuric acid production process, including a dynamic wave scrubber, a scrubbing liquid circulation pump, a high-voltage electrostatic demister, and a scrubbing liquid cooler. The sulfur dioxide-containing process gas after being cooled by heat exchange in the cracking incinerator outlet and the waste heat recovery boiler enters from the inlet of the dynamic wave scrubber. The scrubbing liquid sprayed in the dynamic wave scrubber contacts the sulfur dioxide-containing process gas. The scrubbing liquid with a temperature lower than that of the sulfur dioxide-containing process gas exchanges heat with the sulfur dioxide process gas and condenses the water vapor in the sulfur dioxide process gas to remove the moisture in the sulfur dioxide-containing process gas and increase the sulfuric acid concentration of the process gas. The sulfur dioxide-containing process gas after concentration enters the high-voltage electrostatic demister from the dynamic wave scrubber. Under the action of the high-voltage electric field in the high-voltage electrostatic demister, the moisture entrained in the sulfur dioxide-containing process gas is further removed, and the sulfuric acid concentration of the process gas is further increased. A part of the scrubbing liquid flowing down and sprayed in the dynamic wave scrubber is recycled back to the dynamic wave scrubber for spraying through the scrubbing liquid circulation pump. Another part of the scrubbing liquid flowing down from the dynamic wave scrubber enters the sulfur degassing system through the scrubbing liquid circulation pump for the desorption of sulfur dioxide, and the generated sulfur dioxide process gas enters the high-voltage electrostatic demister.

[0011] Preferably, the scrubbing liquid sprayed down in the dynamic wave scrubber enters the scrubbing liquid circulation pump from the bottom of the dynamic wave scrubber and is discharged from the scrubbing liquid circulation pump. A part of the scrubbing liquid discharged from the scrubbing liquid circulation pump enters the scrubbing liquid cooler and is recycled back to the inside of the dynamic wave scrubber for spraying again. Another part of the scrubbing liquid flows into the sulfur degassing system.

[0012] Preferably, the sulfur degassing system includes a sulfur dioxide remover and a scrubbing solution desorption circulation pump. The scrubbing solution from the scrubbing solution circulation pump flows into the sulfur dioxide remover from the upper part, and the hot air enters from the lower part of the sulfur dioxide remover. The two contact reversely inside the sulfur dioxide remover for the desorption of sulfur dioxide. The sulfur dioxide process gas generated inside the sulfur dioxide remover enters the dynamic wave scrubber and mixes with the concentrated sulfur dioxide-containing process gas, and then enters the high-voltage electrostatic demister. The scrubbing solution spraying down inside the sulfur dioxide remover enters the scrubbing solution desorption circulation pump and then flows back to the upper part of the sulfur dioxide remover for spraying again to desorb sulfur dioxide again.

[0013] Preferably, the sulfur dioxide-containing process gas removed by the high-voltage electrostatic demister is introduced into a process gas heater for heating, and temperature rise treatment is carried out in the process gas heater. The heated sulfur dioxide-containing process gas enters a segmented sulfur dioxide reactor with a PTOL-WXP series catalyst bed arranged inside. Inside the segmented sulfur dioxide reactor, the sulfur dioxide gas in the sulfur dioxide-containing process gas is oxidized to sulfur trioxide gas. The process gas after reaction in the segmented sulfur dioxide reactor enters the glass tube condenser for condensation. The formed sulfuric acid condensate flows into the sulfuric acid condensate collection tank from the outlet at the bottom of the glass tube condenser. The purified tail gas is discharged from the top of the glass tube condenser and discharged through the tail gas discharge chimney. The liquid sulfuric acid stored in the sulfuric acid condensate collection tank flows into the sulfuric acid cooler, is heat-exchanged and cooled in the sulfuric acid cooler, and then flows out of the sulfuric acid cooler and is stored in the sulfuric acid storage tank.

[0014] Preferably, the reaction temperature of the sulfur dioxide-containing process gas in the segmented sulfur dioxide reactor is controlled at 380 - 420 °C by heating through the high-voltage electrostatic demister. A finned heat exchanger is provided at the outlet of the segmented sulfur dioxide reactor to control the temperature of the process gas through the finned heat exchanger and keep it between 270 and 290 °C.

[0015] Preferably, glass tube condensate pipes are provided inside the glass tube condenser. The process gas side of the glass tube condensate pipes maintains a slightly negative pressure of 0 to -1 KPa, and the outlet temperature of the glass tube condenser is controlled at 90 to 110 °C.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The treatment method for increasing the sulfuric acid concentration in low-sulfur flue gas during the wet sulfuric acid production process can remove the moisture in the flue gas by using a dynamic wave scrubber and a high-voltage electrostatic demister, thereby relatively increasing the concentration of sulfur dioxide in the process gas. The washing liquid is desorbed by the sulfur degassing system to generate sulfur dioxide gas, further increasing the concentration of sulfur dioxide, thus ensuring the concentration of the sulfuric acid product. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is a schematic diagram of the treatment process for increasing the sulfuric acid concentration in low-sulfur flue gas during the wet sulfuric acid production process of the present invention.

[0019] In the figure: 1, dynamic wave scrubber; 2, washing liquid circulation pump; 3, sulfur dioxide remover; 4, washing liquid desorption circulation pump; 5, high-voltage electrostatic demister; 6, process gas heater; 7, sulfuric acid condensate collection tank; 8, glass tube condenser; 9, segmented sulfur dioxide reactor; 10, sulfuric acid cooler; 11, sulfuric acid storage tank; 12, tail gas discharge chimney; 13, washing liquid cooler. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0021] Embodiment: As Figure 1 shown, the present invention provides a treatment method for increasing the sulfuric acid concentration in low-sulfur flue gas during the wet sulfuric acid production process, including a dynamic wave scrubber 1, a washing liquid circulation pump 2, a high-voltage electrostatic demister 5, and a washing liquid cooler 13. The sulfur dioxide-containing process gas, which has been cooled by heat exchange in the outlet of the cracking incinerator and the waste heat recovery boiler, enters from the inlet of the dynamic wave scrubber 1. The scrubbing liquid sprayed in the dynamic wave scrubber 1 contacts the sulfur dioxide-containing process gas, and heat exchange is carried out on the sulfur dioxide-containing process gas by the scrubbing liquid whose temperature is lower than that of the sulfur dioxide-containing process gas. When the dynamic wave scrubber processes the gas containing steam (such as water vapor) or high-temperature gas, when the high-temperature gas contacts the cooling liquid (usually water or chemical solution), the gas temperature suddenly drops below the dew point, and the condensable components therein (here it is water vapor) undergo a phase change and condense from the gaseous state to the liquid state. The sulfur dioxide-containing high-temperature process gas forms a countercurrent contact with the scrubbing liquid sprayed in the dynamic wave scrubber 1, that is, the sulfur dioxide-containing high-temperature process gas gradually contacts the newly sprayed scrubbing liquid during the process of advancing, achieving a relatively fast cooling effect. The scrubbing liquid forms a "foam zone" (dynamic wave zone) through high-pressure nozzles, generating extremely high turbulence and surface area, strengthening the gas-liquid heat and mass transfer, and condensing the water vapor in the sulfur dioxide-containing process gas, removing the moisture in the sulfur dioxide-containing process gas to increase the sulfuric acid concentration of the process gas. In the way of reducing the moisture in the sulfur dioxide-containing high-temperature process gas, the concentration of sulfur dioxide in the sulfur dioxide-containing high-temperature process gas is increased; The concentrated sulfur dioxide-containing process gas enters the high-voltage electrostatic demister 5 from the dynamic wave scrubber 1. Under the action of the high-voltage electric field in the high-voltage electrostatic demister 5, the moisture entrained in the sulfur dioxide-containing process gas is further removed, and the sulfuric acid concentration of the process gas is further increased. The particles are charged through corona discharge and are captured under the action of the electric field, that is, high-voltage direct current is applied to the discharge electrode to form a strong electric field, ionizing the gas around the electrode to generate a large number of free electrons and ions (corona region). When the droplets or particles in the gas pass through the corona region, they collide with electrons or ions and adsorb charges to become charged particles. The charged particles move directionally towards the dust collecting electrode (usually a metal tube or plate) under the action of the electric field force. After the particles hit the dust collecting electrode, they lose their charges and are removed from the surface of the electrode by gravity or liquid flushing (spraying water film), realizing the removal of moisture from the process gas and further increasing the concentration of sulfuric acid; A part of the scrubbing liquid flowing down and sprayed in the dynamic wave scrubber 1 is recycled back to the dynamic wave scrubber 1 for spraying again through the scrubbing liquid circulation pump 2. Another part of the scrubbing liquid flowing down from the dynamic wave scrubber 1 enters the sulfur degassing system through the scrubbing liquid circulation pump 2 for the desorption of sulfur dioxide. The generated sulfur dioxide process gas enters the high-voltage electrostatic demister 5. The chemical reaction of the sulfur degassing system for the desorption of the scrubbing liquid is as follows: 2NaHSO3 Na2SO3+SO2↑+H2O The washing liquid is desorbed by the thermal desorption method, and sulfur dioxide gas is desorbed. Therefore, a small amount of sulfur dioxide gas dissolved in the washing liquid is extracted and combined with the sulfur dioxide-containing steam with part of the moisture removed in the dynamic wave scrubber 1 to increase the sulfur dioxide concentration therein and improve the recovery rate of sulfur dioxide.

[0022] The washing liquid sprayed down in the dynamic wave scrubber 1 enters the washing liquid circulation pump 2 from the bottom of the dynamic wave scrubber 1 and is discharged from the washing liquid circulation pump 2. That is, through the pressurized transportation of the washing liquid circulation pump 2, the washing liquid flowing to the bottom of the dynamic wave scrubber 1 can be transported and enabled to be sprayed again to achieve the effect of full utilization of the washing liquid. Part of the washing liquid discharged from the washing liquid circulation pump 2 enters the washing liquid cooler 13 and returns to the inside of the dynamic wave scrubber 1 for re-spraying. The washing liquid is transported to the washing liquid cooler 13 by the washing liquid circulation pump 2, exchanges heat and cools down, and then enters the dynamic wave scrubber to continue circulating. Through the cooling of the washing liquid cooler 13, the reduction in the moisture removal effect caused by the excessively high temperature of the washing liquid after heat exchange with the sulfur dioxide-containing steam is effectively avoided, thus ensuring that the dynamic wave scrubber 1 can stably remove the moisture in the sulfur dioxide-containing steam. Another part of the washing liquid flows into the sulfur degassing system. That is, while removing the moisture in the sulfur dioxide-containing steam, a small amount of sulfur dioxide gas will be relatively dissolved in the washing liquid. By desorbing the washing liquid, the sulfur dioxide gas inside can be extracted, which ensures the smooth circulation of the washing liquid and extracts the dissolved sulfur dioxide gas, thereby increasing the sulfur dioxide concentration.

[0023] The sulfur degassing system includes a sulfur dioxide remover 3 and a washing liquid desorption circulation pump 4. The washing liquid from the washing liquid circulation pump 2 flows into the upper part of the sulfur dioxide remover 3. That is, the washing liquid entering the sulfur dioxide remover 3 can be sprayed down from top to bottom, and the hot air enters from the lower part of the sulfur dioxide remover 3 and contacts reversely inside the sulfur dioxide remover 3 for the desorption of sulfur dioxide. That is, by contacting the hot air with the washing liquid, the thermal desorption of the washing liquid can be promoted, so that the dissolved sulfur dioxide in the washing liquid can be desorbed. The sulfur dioxide process gas generated in the sulfur dioxide remover 3 enters the dynamic wave scrubber 1 and is mixed with the concentrated sulfur dioxide-containing process gas and then enters the high-voltage electrostatic demister 5, so that the desorbed sulfur dioxide gas can be mixed with the sulfur dioxide-containing steam to increase the sulfur dioxide concentration. The washing liquid sprayed down in the sulfur dioxide remover 3 enters the washing liquid desorption circulation pump 4 and then returns to the upper part of the sulfur dioxide remover 3 for spraying again to desorb sulfur dioxide again.

[0024] The process gas containing sulfur dioxide removed by the high-voltage electrostatic demister 5 is introduced into the process gas heater 6 for heating. Temperature raising treatment is carried out in the process gas heater 6. The sulfur dioxide steam discharged from the high-voltage electrostatic demister 5 is heated by the process gas heater 6 and heated to the most suitable temperature for the catalytic oxidation of the PTOL-WXP series catalyst, so as to reach the most suitable temperature for the oxidation of sulfur dioxide to sulfur trioxide, improve the conversion efficiency of sulfur dioxide, and ensure its full and stable conversion. The chemical reaction of catalytic oxidation of sulfur dioxide in its sectionalized sulfur dioxide reactor 9 is as follows:

[0025] In this way, the sulfur dioxide in the flue gas can be recycled. The heated process gas containing sulfur dioxide enters the sectionalized sulfur dioxide reactor 9 with the PTOL-WXP series catalyst bed arranged inside. In the sectionalized sulfur dioxide reactor 9, the sulfur dioxide gas in the process gas containing sulfur dioxide is oxidized into sulfur trioxide gas. The sectionalized sulfur dioxide reactor 9 is of multiple sections and can be provided with one or more catalyst beds according to the specific content of the process gas components, so that it can be adjusted according to specific uses, making its different uses more convenient. The process gas after reaction in the sectionalized sulfur dioxide reactor 9 enters the glass tube condenser 8 for condensation. The formed sulfuric acid condensate flows into the sulfuric acid condensate collection tank 7 from the outlet at the bottom of the glass tube condenser 8. The purified tail gas is discharged from the top of the glass tube condenser 8 and discharged through the tail gas discharge chimney 12. Through the condensation of the glass tube condenser 8, the exothermic reaction of gaseous sulfur trioxide with water and the phase change form sulfuric acid. The reaction of sulfur trioxide with water is as follows:

[0026] The liquid sulfur stored in the sulfuric acid condensate collection tank 7 flows into the sulfuric acid cooler 10, is heat-exchanged and cooled in the sulfuric acid cooler 10, and flows out of the sulfuric acid cooler 10 and is stored in the sulfuric acid storage tank 11. The sulfuric acid liquid is cooled by the sulfuric acid cooler 10 to ensure its normal storage for long-term storage.

[0027] By heating the high-voltage electrostatic demister 5, the reaction temperature of the process gas containing sulfur dioxide in the sectionalized sulfur dioxide reactor 9 is controlled at 380 - 420 °C. The outlet of the segmented sulfur dioxide reactor 9 is provided with a finned heat exchanger, which controls the temperature of the process gas through the finned heat exchanger and keeps it between 270 and 290 °C. The finned heat exchanger can preliminarily cool the sulfur trioxide steam discharged from the segmented sulfur dioxide reactor 9 to prevent its temperature from being too high, which may affect the condensation of sulfur trioxide, thus ensuring that sulfur trioxide can be condensed relatively stably.

[0028] The glass tube condenser 8 is provided with a glass tube condenser tube. The process gas side of the glass tube condenser tube maintains a slightly negative pressure of 0 to -1 kPa to reduce the boiling point of water in the sulfur trioxide process gas and remove more moisture to control the sulfuric acid concentration. The outlet temperature of the glass tube condenser is controlled between 90 and 110 °C.

[0029] In the treatment method for increasing the sulfuric acid concentration of low-sulfur flue gas in the wet sulfuric acid process, during use, the sulfur dioxide-containing process gas enters the inside of the kinetic wave scrubber 1 and contacts the scrubbing liquid under the action of the spray heads inside the kinetic wave scrubber 1, and the moisture in the sulfur dioxide-containing process gas can be removed. The sprayed scrubbing liquid enters the scrubbing liquid circulation pump 2, and under the transportation of the scrubbing liquid circulation pump 2, part of the scrubbing liquid enters the scrubbing liquid cooler 13 for cooling and is then re-transported to the spray heads, and the other part is transported to the sulfur dioxide remover 3, and hot air is injected into the sulfur dioxide remover 3 to desorb the scrubbing liquid to generate sulfur dioxide gas. Under the action of the scrubbing liquid desorption circulation pump 4, the scrubbing liquid in the sulfur dioxide remover 3 can be cyclically desorbed. The generated sulfur dioxide gas enters the kinetic wave scrubber 1 and mixes with the moisture-removed process gas, and then enters the high-voltage electrostatic demister 5. Under the action of the high-voltage electric field in the high-voltage electrostatic demister 5, the moisture entrained in the sulfur dioxide-containing process gas is further removed, and then it is heated by the process gas heater 6 to reach the temperature suitable for the catalytic oxidation of sulfur dioxide to sulfur trioxide and is oxidized in the segmented sulfur dioxide reactor 9. The generated sulfur trioxide process gas is cooled by the finned heat exchanger and condensed in the glass tube condenser 8 to generate sulfuric acid condensate, which falls into the sulfuric acid condensate collection tank 7 and is cooled by the sulfuric acid cooler 10 and stored in the sulfuric acid storage tank 11. The tail gas generated by the glass tube condenser 8 is discharged from the tail gas discharge chimney 12.

[0030] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made in these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A treatment method for increasing the sulfuric acid concentration of low-sulfur flue gas in the wet sulfuric acid production process, including a dynamic wave scrubber (1), a scrubbing liquid circulation pump (2), a high-voltage electrostatic demister (5), and a scrubbing liquid cooler (13), characterized in that: The sulfur dioxide-containing process gas cooled by heat exchange in the cracking incinerator outlet and the waste heat recovery boiler enters from the inlet of the dynamic wave scrubber (1). The scrubbing liquid sprayed in the dynamic wave scrubber (1) contacts the sulfur dioxide-containing process gas. The scrubbing liquid with a temperature lower than that of the sulfur dioxide-containing process gas exchanges heat with the sulfur dioxide-containing process gas and condenses the water vapor in the sulfur dioxide process gas, removing the moisture in the sulfur dioxide-containing process gas to increase the sulfuric acid concentration of the process gas. The sulfur dioxide-containing process gas after concentration improvement enters the high-voltage electrostatic demister (5) from the dynamic wave scrubber (1). Under the action of the high-voltage electric field in the high-voltage electrostatic demister (5), the moisture entrained in the sulfur dioxide-containing process gas is further removed, further increasing the sulfuric acid concentration of the process gas. A part of the scrubbing liquid flowing down by spraying in the dynamic wave scrubber (1) is refluxed to the dynamic wave scrubber (1) for spraying again through the scrubbing liquid circulation pump (2). Another part of the scrubbing liquid flowing down from the dynamic wave scrubber (1) enters the sulfur degassing system through the scrubbing liquid circulation pump (2) for desorption of sulfur dioxide, and the generated sulfur dioxide process gas enters the high-voltage electrostatic demister (5).

2. The treatment method for increasing the sulfuric acid concentration of low-sulfur flue gas in the wet sulfuric acid production process according to claim 1, wherein: The scrubbing liquid sprayed down in the dynamic wave scrubber (1) enters the scrubbing liquid circulation pump (2) from the bottom of the dynamic wave scrubber (1) and is discharged from the scrubbing liquid circulation pump (2). A part of the scrubbing liquid discharged from the scrubbing liquid circulation pump (2) enters the scrubbing liquid cooler (13) and is refluxed to the inside of the dynamic wave scrubber (1) for spraying again. Another part of the scrubbing liquid flows into the sulfur degassing system.

3. The treatment method for increasing the sulfuric acid concentration of low-sulfur flue gas in the wet sulfuric acid production process according to claim 2, characterized in that: The sulfur degassing system includes a sulfur dioxide remover (3) and a scrubbing liquid desorption circulation pump (4). The scrubbing liquid from the scrubbing liquid circulation pump (2) flows into the upper part of the sulfur dioxide remover (3), and its hot air enters from the lower part of the sulfur dioxide remover (3), and reverse contact occurs inside the sulfur dioxide remover (3) for desorption of sulfur dioxide. The sulfur dioxide process gas generated inside the sulfur dioxide remover (3) enters the dynamic wave scrubber (1) to be mixed with the sulfur dioxide-containing process gas after concentration improvement and enters the high-voltage electrostatic demister (5). The scrubbing liquid sprayed down inside the sulfur dioxide remover (3) enters the scrubbing liquid desorption circulation pump (4) and is refluxed to the upper part of the sulfur dioxide remover (3) to be sprayed out again for desorption of sulfur dioxide again.

4. A treatment method for increasing the sulfuric acid concentration of low-sulfur flue gas during the wet sulfuric acid production process according to claim 3, characterized in that: The sulfur dioxide-containing process gas removed by the high-voltage electric field of the high-voltage electrostatic demister (5) is introduced into the process gas heater (6) for heating, and temperature raising treatment is carried out in the process gas heater (6). The heated process gas containing sulfur dioxide enters a segmented sulfur dioxide reactor (9) with a PTOL-WXP series catalyst bed arranged inside, and in the segmented sulfur dioxide reactor (9), the sulfur dioxide gas in the process gas containing sulfur dioxide is oxidized into sulfur trioxide gas; The process gas after reaction in the segmented sulfur dioxide reactor (9) enters a glass tube condenser (8) for condensation. The formed sulfuric acid condensate flows into a sulfuric acid condensate collection tank (7) from the outlet at the bottom of the glass tube condenser (8). The purified tail gas is discharged from the top of the glass tube condenser (8) and discharged through a tail gas discharge chimney (12); The liquid sulfuric acid stored in the sulfuric acid condensate collection tank (7) flows into a sulfuric acid cooler (10), is heat-exchanged and cooled in the sulfuric acid cooler (10), and flows out of the sulfuric acid cooler (10) to be stored in a sulfuric acid storage tank (11).

5. The treatment method for increasing the sulfuric acid concentration of low-sulfur flue gas in the wet sulfuric acid production process according to claim 4, wherein: The reaction temperature of the process gas containing sulfur dioxide in the segmented sulfur dioxide reactor (9) is controlled at 380 - 420 °C by heating the high-voltage electrostatic demister (5); A finned heat exchanger is provided at the outlet of the segmented sulfur dioxide reactor (9). The temperature of the process gas is adjusted by the finned heat exchanger and controlled between 270 and 290 °C.

6. A treatment method for increasing the sulfuric acid concentration of low-sulfur flue gas in the wet sulfuric acid production process according to claim 5, characterized in that: A glass tube condensation tube is provided inside the glass tube condenser (8). The process gas side of the glass tube condensation tube maintains a slightly negative pressure of 0 to -1 KPa, and the outlet temperature of the glass tube condenser is controlled at 90 to 110 °C.

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