Sulfur tail gas treatment methods and systems

Abstract

This invention discloses a method for treating sulfur tail gas, comprising: cooling the sulfur tail gas to separate sulfur from the tail gas; and using a treatment liquid containing sulfur-autotrophic denitrifying microorganisms to convert the sulfur into sulfate ions. This invention also discloses a sulfur tail gas treatment system, comprising a biochemical reaction tank and a treatment liquid tank. The biochemical reaction tank is equipped with a spray system and contains biological packing material. The spray system is connected to the treatment liquid tank, and the packing material is covered with sulfur-autotrophic denitrifying microorganisms. The sulfur tail gas treatment system provided by this invention, based on the traditional water washing method, adds microbial treatment to oxidize the sulfur retained by water washing into sulfate ions, which are then dissolved in water and discharged. This not only meets relevant tail gas emission standards but also prevents sulfur particles from adhering to the inner wall of the treatment system and the pipes, thus avoiding pipe blockage.

Description

Technical Field

[0001] This invention belongs to the field of sulfur tail gas treatment technology, and relates to sulfur tail gas treatment methods and systems. Background Art

[0002] During sulfur recovery, most liquid sulfur is converted into solid sulfur, producing sulfur vapor and H2S gas, which are emitted directly into the atmosphere, causing air pollution. Similarly, other production processes that use liquid sulfur as a raw material, such as sulfur-coated urea, sulfur-bentonite, and sulfur concrete, also involve the emission of sulfur vapor. If emitted directly without treatment, this not only causes air pollution but also harms the health of workers in the production area.

[0003] Existing methods for treating sulfur tail gas mostly employ water washing to cool the sulfur vapor and convert it into a solid, thereby trapping the sulfur in the washing solution and preventing it from entering the atmosphere. While this method can significantly reduce sulfur vapor in the tail gas and meet environmental emission standards, the sulfur vapor is generally converted into solid sulfur particles after water washing. These sulfur particles easily adhere to the inner walls of the processor and the exhaust pipes, making them difficult to remove and potentially causing blockages in severe cases. Summary of the Invention

[0004] The purpose of this invention is to provide a method for treating sulfur tail gas, which uses sulfur autotrophic denitrifying microorganisms to treat the sulfur particles formed after the sulfur tail gas is cooled, thereby preventing the sulfur particles from clogging the pipeline.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for treating sulfur tail gas includes: cooling the sulfur tail gas to separate sulfur from the tail gas; and dissolving the sulfur using a treatment solution containing sulfur-autotrophic denitrifying microorganisms.

[0007] Optionally, the step of cooling the sulfur tail gas to separate sulfur from the tail gas includes cooling the sulfur tail gas with the treatment liquid.

[0008] Optionally, the treatment solution contains NO3. - and NH4 + The nitrogen content in the treatment solution is 1–20 mmol / L, and the NH4+ content is... + and NO3 - The molar ratio is approximately 0.08.

[0009] Optionally, the treatment solution further contains PO4. 3- The molar ratio of nitrogen to phosphorus in the treatment solution is 1:10 to 1:11.

[0010] Optionally, the pH value of the treatment solution is 7.5 to 9.0.

[0011] Optionally, the treatment solution may also contain sodium bicarbonate or sodium carbonate.

[0012] Optionally, the treatment solution contains biological packing material.

[0013] The present invention also provides a sulfur tail gas treatment system, including a biochemical reaction tank containing a treatment liquid, an air inlet pipe connected to the lower part of the biochemical reaction tank and an exhaust pipe connected to the top of the tank, wherein the treatment liquid contains sulfur autotrophic denitrifying microorganisms.

[0014] Optionally, the upper part of the biochemical reaction vessel is also provided with a liquid distribution pipe, which extends horizontally inside the biochemical reaction vessel and is connected to multiple water distributors or nozzles; the liquid distribution pipe is connected to a liquid inlet pipe provided outside the biochemical reaction vessel.

[0015] Optionally, it also includes a processing liquid tank, and the bottom of the biochemical reaction tank is connected to a drain pipe. The processing liquid tank is connected to the inlet pipe and the drain pipe respectively.

[0016] Optionally, a pH probe socket is formed on the treatment liquid tank, and a pH probe is inserted into the pH probe socket.

[0017] Optionally, it also includes a buffer tank, and a buffer addition tube is connected between the buffer tank and the processing liquid tank.

[0018] Optionally, the biochemical reaction vessel is filled with biological packing material, which is immersed in the treatment solution.

[0019] Optionally, the volume of the biological packing material accounts for 30% to 80% of the volume of the biochemical reaction vessel.

[0020] Optionally, the biochemical reaction vessel is also fixedly connected with a grid plate for supporting the biological packing material.

[0021] Optionally, a circulation pump is connected to the inlet pipe.

[0022] Optionally, a metering pump is connected to the buffer addition tube.

[0023] The beneficial effects of this invention include:

[0024] 1. The sulfur tail gas treatment method provided by the present invention is based on the traditional water washing method. It utilizes sulfur autotrophic denitrifying microorganisms to treat the solid sulfur separated from the sulfur tail gas, oxidizing the solid sulfur particles into sulfates, which are then dissolved in water and discharged. This not only ensures that the sulfur content in the sulfur tail gas emitted into the atmosphere meets environmental protection requirements, but also prevents sulfur particles from adhering to the surface and clogging the pipes.

[0025] 2. The sulfur tail gas treatment system provided by this invention is applicable to the sulfur tail gas treatment method described above. The sulfur tail gas treatment system provided by this invention, by setting up a biochemical reaction tank, ensures that the treatment of sulfur tail gas is carried out in a closed environment, preventing the sulfur tail gas from entering the atmosphere before treatment. Simultaneously, the treatment liquid containing sulfur-autotrophic denitrifying microorganisms used to treat sulfur in the sulfur tail gas treatment system is also directly used to cool the sulfur tail gas, and the treatment liquid is recycled, effectively improving the utilization rate of the chemical components in the treatment liquid, reducing the amount of waste liquid generated, and lowering the treatment cost of sulfur tail gas. Since the solid sulfur in the biochemical reaction tank is converted into sulfate by the sulfur-autotrophic denitrifying microorganisms, the blockage of the pipes on the biochemical reaction tank by solid sulfur is prevented. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the sulfur tail gas treatment system disclosed in this invention.

[0027] In the diagram: 1. Air inlet pipe; 2. Exhaust pipe; 3. Liquid distribution pipe; 4. Grating plate; 5. Biological packing material; 6. Drain pipe; 7. Biochemical reaction vessel; 8. Circulation pump; 9. Liquid inlet pipe; 10. Liquid addition pipe; 11. Buffer solution addition pipe; 12. pH probe; 13. Vent pipe; 14. Processing liquid tank; 15. Buffer solution tank; 16. Metering pump. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] Sulfur autotrophic denitrification technology is a process in which sulfur autotrophic denitrifying microorganisms, using sulfur as the fuel, produce sulfur-containing nitrogen ... 2- Or, reduced sulfur such as elemental sulfur (S) can act as an electron donor, using CO32-. 2- HCO3 - CO2 is an inorganic carbon source, and NO3 is used to... - The process of reducing sulfur to N2 and simultaneously oxidizing it to sulfate.

[0030] The chemical reaction formula for denitrification, which uses elemental sulfur as an electron donor, is as follows:

[0031] NO3 - +1.1S + 0.4CO2 + 0.76H2O + 0.08NH4 + →0.5N2 + 1.1SO4 2- +1.28H + +0.08C5H7O2N (1-1)

[0032] Therefore, in the process of treating sulfur tail gas, sulfur autotrophic denitrifying microorganisms can be used to treat the solid sulfur produced after the tail gas is cooled, so that the solid sulfur dissolves in water.

[0033] Therefore, based on the above-mentioned sulfur autotrophic denitrification technology, this invention proposes a method for treating sulfur tail gas, including the following steps:

[0034] S101: The step of cooling the sulfur tail gas to separate the sulfur from the tail gas;

[0035] The sulfur in the sulfur tail gas exists in the form of sulfur vapor. By cooling the sulfur tail gas, the mixed sulfur vapor eventually turns into solid sulfur, thus separating the sulfur from the tail gas and desulfurizing it.

[0036] The sulfur tail gas can be cooled by washing it with water. In an optional embodiment, the sulfur tail gas is introduced into a sealed container and washed with water in the sealed container to cool it down.

[0037] S102: Step of dissolving solid sulfur using a treatment solution containing sulfur-containing autotrophic denitrifying microorganisms.

[0038] Solid sulfur separated from sulfur tail gas is treated with a treatment solution containing sulfur-autotrophic denitrifying microorganisms to convert the solid sulfur into water-soluble sulfate ions.

[0039] In an optional embodiment, the cooling of the sulfur vapor and the treatment of the solid sulfur separated from the cooled sulfur tail gas are both carried out in a sealed container. Specifically, the sealed container has a sealable inlet and outlet pipe. The sulfur tail gas enters the sealed container through the inlet pipe, is cooled by water washing within the sealed container, and contains a treatment liquid. The separated solid sulfur falls into the treatment liquid layer, where sulfur autotrophic denitrifying microorganisms convert the sulfur into sulfate ions.

[0040] The treatment solution contains sulfur-autotrophic denitrifying microorganisms and also contains NH4. + and NO3 - And CO3 as a carbon source 2- and / or HCO3 - This is to ensure the progress of sulfur autotrophic denitrification reaction.

[0041] Optionally, since the most suitable living environment for sulfur autotrophic denitrifying microorganisms is a neutral or slightly alkaline environment, the pH value of the treatment solution is 7.5 to 9.0.

[0042] Optionally, the nitrogen content in the treatment solution is 1–20 mmol / L. Further, the treatment solution contains NH4+.+ and NO3 - The molar ratio is approximately 0.08.

[0043] The growth of sulfur-autotrophic denitrifying microorganisms also requires the supply of essential phosphorus, therefore the treated liquid also contains PO4. 3- PO4 3- It is a nutrient required for the growth of sulfur-autotrophic denitrifying microorganisms. The nitrogen and phosphorus elements in the treatment solution can not only provide the necessary nutrients for the growth and reproduction of the microorganisms, but also contain nitrogen-containing NO3. - and NH4 + It is also an essential reaction material for sulfur-autotrophic denitrifying microorganisms to carry out denitrification reactions.

[0044] Specifically, the molar ratio of nitrogen to phosphorus in the treatment solution is 110 to 11.

[0045] Referring to reaction formula 1-1, solid sulfur is converted into SO4 by sulfur autotrophic denitrifying microorganisms. 2- At the same time, H will also be generated + This causes the H in the treatment solution to + The continuous increase in pH leads to a decrease in the pH of the treated liquid. Sulfate-autotrophic denitrifying microorganisms thrive in neutral or slightly alkaline environments; acidic environments negatively impact their survival, resulting in decreased denitrification efficiency. Therefore, sodium bicarbonate or sodium carbonate is added to the treated liquid. Sodium bicarbonate or sodium carbonate can, on the one hand, consume the large amount of H₂ produced by the denitrification reaction. + This maintains the pH of the treatment solution at a neutral or slightly alkaline level, and also provides and supplements the inorganic carbon source for the denitrification reaction. In this embodiment, the treatment solution containing sodium bicarbonate and sodium carbonate is an alkaline solution, thus also eliminating small amounts of H2S in the sulfur tail gas, converting the H2S in the sulfur tail gas into Na2S in the treatment solution.

[0046] S formed by transformation 2- Under the action of sulfur-autotrophic denitrifying microorganisms, it is further converted into SO4. 2- The reaction equation is as follows:

[0047] S 2- +1.4272NO3 - +0.1872CO2 + 1.4224H + →SO4 2- +0.0368C5H7NO2+0.5792H2O+0.6952N2(1-2)

[0048] In an optional embodiment, the sulfur autotrophic denitrifying microorganisms used to consume solid sulfur are Thiobacillus denitrificans and Thiomicrospira denitrificans, both of which are widely found in ecosystems such as soil, rivers, lakes, and ponds and are readily available.

[0049] In other alternative embodiments, other types of sulfur autotrophic denitrifying microorganisms may also be selected.

[0050] Furthermore, to ensure the treatment efficiency of sulfur-autotrophic denitrifying microorganisms in the treatment solution for sulfur separated from sulfur tail gas, a biological packing material 5 is installed in the treatment solution. The biological packing material 5 has advantages such as large specific surface area, light weight, and high strength. Therefore, sulfur-autotrophic denitrifying microorganisms adhere to the surface of the biological packing material 5 and form a biofilm using the biological packing material 5 as a carrier, which can greatly increase the number of sulfur-autotrophic denitrifying microorganisms in the treatment solution. At the same time, the large specific surface area of ​​the biological packing material 5 also allows for a larger contact area between the biofilm formed on the surface of the biological packing material 5 and the solid sulfur in the treatment solution, ensuring that the solid sulfur is fully dissolved in the treatment solution.

[0051] The present invention also discloses a sulfur tail gas treatment system based on the sulfur tail gas treatment method described above.

[0052] like Figure 1 As shown, a sulfur tail gas treatment system includes a biochemical reaction tank 7 containing a treatment liquid. The treatment liquid contains sulfur autotrophic denitrifying microorganisms. Sulfur tail gas is introduced into the biochemical reaction tank 7, where it contacts the treatment liquid and undergoes heat exchange. The tail gas cools, and the sulfur vapor in it solidifies into sulfur particles that remain in the treatment liquid. The sulfur autotrophic denitrifying microorganisms in the treatment liquid dissolve the solid sulfur particles. The tail gas, after sulfur vapor removal, is discharged from the biochemical reaction tank 7.

[0053] The biochemical reaction tank 7 includes a tank body, with an inlet pipe 1 fixedly connected to the lower part of the tank body and an exhaust pipe 2 connected to the top of the tank body. Sulfur-containing exhaust gas enters the tank body through the inlet pipe 1. After the exhaust gas is cooled and the sulfur is removed in the biochemical reaction tank 7, it is discharged from the tank body through the exhaust pipe 2. An inlet valve is installed on the inlet pipe 1 to control the amount of gas entering the tank body and prevent excessive sulfur-containing exhaust gas from entering. It should be understood that the liquid level of the treatment liquid is not lower than the installation height of the inlet pipe 1 to ensure that the sulfur exhaust gas entering the biochemical reaction tank 7 first contacts the treatment liquid and is cooled in the treatment liquid. The sulfur vapor in the exhaust gas turns into solid sulfur after cooling and falls into the treatment liquid.

[0054] A liquid inlet pipe 9 is also connected to the reaction tank body, which can deliver the treatment liquid into the reaction tank body to ensure that there is enough treatment liquid in the reaction tank body to replenish the NH4 consumed in the treatment liquid. + NO3 - Inorganic carbon is used to ensure sufficient NH4 in the treatment solution. + NO3 - Inorganic carbon sources enable the denitrification reaction to proceed continuously.

[0055] The reaction tank is also connected to a horizontally extending liquid distribution pipe 3, which is positioned above the treatment liquid layer and is connected to the inlet pipe 9. Multiple water distributors or nozzles are connected to the liquid distribution pipe 3, which can spray the treatment liquid into the reaction tank. The sprayed treatment liquid can scrub the sulfur tail gas passing through the treatment liquid, further reducing the temperature of the tail gas and thus further reducing the sulfur content in the tail gas. Optionally, multiple water distributors or nozzles are evenly distributed and connected to the inlet pipe 9.

[0056] An exhaust valve is also connected to the exhaust pipe for sealing the exhaust pipe 2. When the exhaust pipe 2 is sealed, the exhaust gas passing through the treatment liquid will accumulate at the top of the reaction tank. The treatment liquid sprayed from the inlet pipe 9 can thoroughly wash away these accumulated exhaust gases, further reducing the sulfur content in the exhaust gas.

[0057] Correspondingly, a drain pipe 6 is connected to the bottom of the reaction tank, and a drain valve is connected to the drain pipe 6. This is because the sulfur autotrophic denitrification reaction requires the consumption of NH4 in the treated liquid. + NO3 - and CO3 2- If the treatment solution is not replenished in time, the sulfur autotrophic denitrification reaction in bioreactor 7 will stop, and solid sulfur will gradually accumulate in bioreactor 7. On the other hand, given a fixed volume of treatment solution, the amount of sulfate ions it can dissolve is also fixed. That is, when the amount of sulfate ions dissolved in the treatment solution reaches its maximum dissolution capacity, a large amount of sulfate precipitate will appear in the treatment solution layer. Therefore, the treatment solution in bioreactor 7 must be updated and replaced through the drain pipe to ensure the continuous progress of the denitrification reaction.

[0058] The reaction tank is filled with biological packing material 5, which has a large specific surface area and provides a large number of pores. These biological packing materials 5 are all immersed in the treatment liquid. Solid sulfur particles separated from sulfur tail gas can adhere to the biological packing materials 5. At the same time, these biological packing materials 5 also provide attachment points for sulfur autotrophic denitrification microorganisms, which is conducive to the growth and reproduction of microorganisms. These sulfur autotrophic denitrification microorganisms use the biological packing materials 5 as a carrier to form a biofilm on the surface of the biological packing materials 5, so that these solid particulate sulfur and sulfur autotrophic denitrification microorganisms can come into full contact, and the solid sulfur can be dissolved in the treatment liquid.

[0059] The biochemical reactor 7 is filled with biological packing material 5 to 30%–80% of its volume to ensure a sufficient quantity of biological packing material 5 to provide adequate attachment area for sulfur autotrophic denitrifying microorganisms. Furthermore, a sufficient quantity of biological packing material 5 extends the movement path of the sulfur tail gas in the treated liquid, thus prolonging the contact time between the sulfur tail gas and the treated liquid. The biological packing material 5 also divides the sulfur tail gas entering the biochemical reactor 7 into multiple smaller streams flowing within it, further increasing the contact area between the sulfur tail gas and the treated liquid, allowing for rapid cooling and temperature reduction of the sulfur tail gas within the treated liquid.

[0060] Optionally, the biological filler 5 may be selected from materials with large specific surface area and high porosity, such as polyurethane sponge or MBBR filler.

[0061] A grid plate 4 is also installed inside the biochemical reaction tank 7. The grid plate 4 is fixed to the lower part of the tank body and is used to support the biological packing material 5 inside the tank. The grid plate 4 is located above the air inlet pipe 1. So, after the sulfur tail gas enters the biochemical reaction tank 7, it will pass through the biological packing material 5 during its ascent. This will prolong the movement path of the tail gas in the treatment liquid, allowing the tail gas to remain in the treatment liquid for a longer time. Therefore, the installation of the biological packing material 5 can promote further contact between the treatment liquid and the sulfur tail gas, and can more fully cool the sulfur tail gas, so that the sulfur vapor in the tail gas can be fully converted into solid sulfur particles.

[0062] The grating plate 4 has a hollow structure. Optionally, the grating plate 4 is made of durable and stable materials such as fiberglass and PE.

[0063] The sulfur tail gas treatment system disclosed in this invention also includes a treatment liquid tank 14, which is connected to the inlet pipe 9 and the outlet pipe 2 of the biochemical reaction tank 7, respectively. The treatment liquid tank 14 contains treatment liquid. The treatment liquid tank 14 supplies treatment liquid to the biochemical reaction tank 7 through the inlet pipe 9, and recovers the treatment liquid through the outlet pipe 2. The recovered treatment liquid is then transported back to the biochemical reaction tank 7. This treatment liquid, transported to the biochemical reaction tank 7, is sprayed out from the distribution pipe 3 to scrub the sulfur tail gas above the biochemical reaction tank 7. The recycling of the treatment liquid saves water while ensuring the NH4 content in the treatment liquid is maintained. + NO3 - and CO3 2- The process is fully utilized, reducing the generation of waste liquid and lowering the treatment cost of sulfur tail gas. The circulation of the treatment liquid between the treatment liquid tank 14 and the biochemical reaction tank 7 also ensures that the inlet pipe 9 can continuously spray the treatment liquid into the biochemical reaction tank 7, thus continuously scrubbing the tail gas rising above the biochemical reaction tank 7, so that the sulfur vapor in the tail gas can be fully converted into solid sulfur.

[0064] A circulation pump 8 is connected to the inlet pipe, and the circulation pump 8 drives the treatment liquid in the treatment liquid tank 14 into the biochemical reaction tank 7.

[0065] In addition to cooling the sulfur tail gas, the treatment liquid also supplies NH4 to the biochemical reaction tank 7. + NO3 - and CO3 2- This is to ensure the continuous progress of the sulfur autotrophic denitrification reaction. As the denitrification reaction continues within biochemical reactor 7, the NO3 in the treated liquid... - and NH4 + The content is constantly decreasing, SO4 2- As the concentration of nitrification increases, it is necessary to replenish and replace the treatment solution in a timely manner to ensure the continuous progress of the denitrification reaction. A filling pipe 10 is connected to the top of the treatment solution tank 14, and a vent pipe 13 is connected to its bottom. The filling pipe 10 can add new treatment solution to the treatment solution tank 14, while the vent pipe 13 can discharge some or all of the repeatedly circulated treatment solution from the treatment solution tank 14, ensuring sufficient space within the tank to accommodate new treatment solution.

[0066] Sulfur autotrophic denitrification requires a neutral or weakly alkaline environment to achieve high reaction efficiency; therefore, the new treatment solution is weakly alkaline or at least neutral. As the denitrification reaction continues within biochemical reactor 7, the H₂ in the treatment solution... +The concentration of sulfur dioxide will also increase, causing the pH of the treated liquid to gradually decrease and become acidic. An acidic environment is unfavorable for the survival of sulfur-autotrophic denitrifying microorganisms, thus hindering the sulfur-autotrophic denitrification reaction. Therefore, it is necessary to monitor the pH of the treated liquid during circulation to prevent the concentration of sulfur dioxide in the circulating solution from rising. + Excessive content maintains the treatment solution at a neutral or slightly alkaline level. Therefore, a probe port is provided on the treatment solution tank 14, into which a pH probe 12 is inserted to enable real-time monitoring of the pH value of the treatment solution.

[0067] It should be noted that this invention does not involve any improvement to the pH probe 12, and the pH probe 12 used in this invention can be any product available on the market.

[0068] When the pH value of the treatment liquid in the treatment liquid tank 14 is detected to be less than 7, the negative effects of the acidic treatment liquid can be avoided by replacing the treatment liquid in the treatment liquid tank 14.

[0069] Furthermore, when the pH of the treatment solution is less than 7, the solution may still contain a large amount of NO3. - and NH4 + Directly replacing the treatment fluid may result in material waste. Therefore, the sulfur tail gas treatment system disclosed in this utility model also includes a buffer tank 15, and the treatment fluid tank 14 and the buffer tank 15 are connected. The buffer tank 15 is filled with an alkaline buffer solution. When the pH value of the treatment fluid in the treatment fluid tank 14 is detected to be less than 7, the buffer tank 15 adds buffer solution to the treatment fluid tank 14 to maintain the pH value of the treatment fluid in a neutral or slightly alkaline state.

[0070] Optionally, in this embodiment, the pH value of the treatment solution is required to be maintained between 7.5 and 9.0. Therefore, when the pH probe 12 detects that the pH value of the treatment solution is less than 7.5, the buffer tank 15 will add buffer solution to the treatment solution tank 14.

[0071] Specifically, a buffer addition tube 11 is provided on the processing liquid tank 14, with one end of the buffer addition tube 11 connected to the processing liquid tank 14 and the other end connected to the buffer tank 15.

[0072] Furthermore, when maintaining the pH value of the treatment solution by adding buffer solution, it is also necessary to avoid adding too much buffer solution, which would cause the pH value of the treatment solution to be too high. An excessively alkaline treatment solution is also detrimental to the continuous progress of the sulfur autotrophic denitrification reaction. Therefore, a metering pump 16 is also connected to the buffer solution addition pipe 11 to control the amount of buffer solution added to the treatment solution tank 14.

[0073] An inlet is formed on the buffer tank 15 to facilitate timely replenishment of buffer solution into the buffer tank 15.

[0074] The buffer solution is an alkaline solution prepared from sodium bicarbonate or sodium carbonate, which can not only adjust the pH value of the treatment solution, but also add CO3 to the treatment solution. 2- HCO3 - This provides more carbon source for the denitrification reaction in biochemical reactor 7.

[0075] Workflow: After entering the biochemical reactor 7, the sulfur tail gas first contacts the treatment liquid. Then, the sulfur tail gas rises through the treatment liquid layer, cooling down during contact with the liquid, converting the gaseous sulfur in the tail gas into solid sulfur. After passing through the treatment liquid, the tail gas is further cooled by the treatment liquid sprayed from the inlet pipe 9 at the top of the biochemical reactor 7. Finally, the tail gas, from which the sulfur components have been separated, is discharged from the biochemical reactor 7. The sulfur separated from the tail gas enters the treatment liquid, where sulfur-autotrophic denitrifying microorganisms convert the sulfur into SO4. 2- This prevents sulfur particles trapped in biochemical reaction tank 7 from adhering to the inner wall of the tank and pipes. The exhaust gas contains a small amount of H2S, which can also be converted into Na2S under the action of alkaline treatment liquid.

[0076] During the treatment of sulfur tail gas, the treatment solution in biochemical reactor 7 circulates continuously or intermittently between biochemical reactor 7 and treatment solution tank 14. When the pH value of the treatment solution in treatment solution tank 14 falls below 7.5, buffer tank 15 replenishes the treatment solution tank 14 with a buffer solution prepared with sodium bicarbonate or sodium carbonate to maintain the pH value of the treatment solution within the range of 7.5 to 9.0. The buffer solution also provides an inorganic carbon source for the growth of sulfur autotrophic denitrifying microorganisms. The treatment solution in treatment solution tank 14 needs to be replenished or replaced as needed during use.

[0077] It should be noted that the sulfur tail gas treatment system disclosed in this invention also requires biofilm formation in the biofilter when it is put into operation. In other words, before the system is running, there is no biofilm on the surface of the biological packing material 5 in the biochemical reaction tank 7. Therefore, a biofilm is formed on the surface of the biological packing material 5 before the system is running.

[0078] The formation of a biofilm in the biological packing material 5 first requires the introduction of sulfur autotrophic denitrifying bacteria. This can be achieved by preparing a treatment solution rich in sulfur autotrophic denitrifying bacteria, such as river water, pond water, or sediment leachate. Alternatively, sulfur autotrophic denitrifying microbial agents can be purchased and added to the treatment solution. After the sulfur tail gas treatment system has been running for 30-60 days, a stable sulfur autotrophic denitrifying bacteria community will form on the biological packing material 5. Sulfur autotrophic denitrifying microorganisms must be added to the treatment solution during the biofilm formation process. Once a stable microbial community has formed in the sulfur tail gas treatment system, it is no longer necessary to add these microorganisms to the treatment solution.

[0079] In another alternative embodiment, biofilm formation can be performed before the sulfur tail gas treatment system is activated. Specifically, sulfur autotrophic denitrifying microorganisms are added to the treatment solution, along with a certain amount of reduced sulfur, such as sulfur powder or sodium thiosulfate. The drain pipe at the bottom of the biochemical reactor 7 is closed, allowing the treatment solution to submerge the biological packing 5. The treatment solution in the biochemical reactor 7 is replenished or replaced every 3-5 days, and this cycle is repeated. After 1-30 days, a stable sulfur autotrophic denitrifying bacterial community can be formed on the biological packing 5. The sulfur tail gas treatment system is then activated after a stable bacterial community has been formed.

[0080] It should be noted that the sulfur tail gas mentioned above refers to the tail gas containing sulfur vapor that is to be emitted and generated in industrial production. For example, tail gas containing sulfur vapor generated during sulfur recovery, and sulfur tail gas containing sulfur components generated during the production of sulfur-coated urea, sulfur-bentonite, sulfur concrete, etc.

[0081] The foregoing descriptions and embodiments are provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be easily made to these contents, and the general principles described herein can be applied to other embodiments without creative effort. The present invention is not limited to the foregoing descriptions and embodiments; any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from its scope should be within the protection scope of the present invention.

Claims

1. A method for treating sulfur tail gas, characterized in that, By cooling the sulfur tail gas, sulfur is separated from the tail gas; The process of dissolving the sulfur using a treatment solution containing sulfur-containing autotrophic denitrifying microorganisms includes the following steps: (1) The sulfur tail gas enters a sealed container and is cooled in the sealed container. The sealed container contains a processing liquid, and the separated solid sulfur falls into the processing liquid layer. (2) The separated solid sulfur is contacted with the treatment liquid containing sulfur-autotrophic denitrifying microorganisms; the sulfur-autotrophic denitrifying microorganisms are Thiobacillus denitrificans and / or Thiomicrospira denitrificans. The treatment solution contains: NO3 - NH4 + PO4 3- and CO3 as a carbon source 2- and / or HCO3 - ; The nitrogen content in the treatment solution is 1–20 mmol / L, and NH4+ is present. + and NO3 - The molar ratio is 0.08; the molar ratio of nitrogen to phosphorus in the treatment solution is 110-11; The treatment solution contains biological packing material, and the sulfur autotrophic denitrifying microorganisms attach to the surface of the biological packing material and form a biofilm using the biological packing material as a carrier. (3) The sulfur-autotrophic denitrifying microorganisms use elemental sulfur in sulfur tail gas as an electron donor and NO3 as a source of oxygen. - As an electron acceptor, CO3 2- and / or HCO3 - Using carbon as a source, elemental sulfur is oxidized to SO4. 2- At the same time, NO3 - Restored to N2; (4) When the pH of the treatment solution is lower than 7.5, sodium bicarbonate or a buffer solution prepared with sodium carbonate is added to the treatment solution to maintain pH stability, so that the pH value of the treatment solution is maintained in the range of 7.5 to 9.

0. (5) When the amount of sulfate ions dissolved in the treatment liquid reaches the maximum value that the treatment liquid can dissolve, a large amount of sulfate precipitate will appear in the treatment liquid layer. By updating and replacing the treatment liquid, the denitrification reaction can continue. The treated tail gas is discharged through the exhaust pipe, and the treatment liquid is recycled.

2. A sulfur tail gas treatment system for implementing the treatment method described in claim 1, characterized in that, include: Biochemical reaction vessel: The biochemical reaction vessel contains a treatment solution; the treatment solution is immersed in biological packing material, and the surface of the biological packing material is covered with sulfur autotrophic denitrifying bacteria; the sulfur autotrophic denitrifying bacteria are Thiobacillus denitrificans and / or Thiomicrospira denitrificans; the volume of the biological packing material occupies 30% to 80% of the volume of the biochemical reaction vessel, and the biological packing material is polyurethane sponge or MBBR packing material. An air inlet pipe is fixedly connected to the lower part of the biochemical reaction tank, and an exhaust pipe is connected to the top of the tank body. The liquid level of the treatment liquid is not lower than the installation height of the air inlet pipe. The upper part of the biochemical reaction tank is also provided with a liquid distribution pipe, which extends horizontally inside the biochemical reaction tank and is connected to multiple water distributors or nozzles; the liquid distribution pipe is located above the treatment liquid layer and is connected to an inlet pipe located outside the biochemical reaction tank; a drain pipe is also connected to the bottom of the biochemical reaction tank. Processing liquid tank: The processing liquid tank stores the processing liquid, which contains NO3. - NH4 + CO3 2- / HCO3 - PO4 3- The treatment liquid tank is connected to the inlet pipe and the outlet pipe respectively; the inlet pipe is connected to the distribution pipe and nozzle of the biochemical reaction tank through a circulation pump; a probe socket is formed on the treatment liquid tank, and a pH probe is inserted into the probe socket; pH probe: When pH < 7.5, turn on the metering pump to add buffer solution to the treatment tank; Buffer tank: A buffer addition tube connects the buffer tank and the treatment solution tank; a metering pump is connected to the buffer addition tube; an inlet is formed on the buffer tank to facilitate timely replenishment of buffer solution. The buffer solution is an alkaline solution prepared from sodium bicarbonate or sodium carbonate, which can not only adjust the pH value of the treatment solution but also add CO3 to the treatment solution. 2- and / or HCO3 - This provides more carbon source for the denitrification reaction in the biochemical reactor.

3. The sulfur tail gas treatment system according to claim 2, characterized in that, Before the sulfur tail gas treatment system is put into operation, the biofilter is activated to form a biofilm on the surface of the biological packing material. Only after a stable sulfur autotrophic denitrifying bacteria community can be formed on the biological packing material can the sulfur tail gas treatment system be activated.

4. The sulfur tail gas treatment system according to claim 2, characterized in that: The biochemical reaction vessel is also fixedly connected to a grid plate for supporting the biological packing material.

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