Small-scale high-sulfur natural gas desulfurization method

Abstract

The invention discloses a small-scale high-sulfur-content natural gas desulfurization method which comprises the following steps: by taking an iron ion / biological bacterium mixed solution as a desulfurizing agent, performing countercurrent contact on raw material natural gas and the iron ion / biological bacterium mixed solution in a desulfurizing tower, and performing multi-stage desulfurization to remove H2S in the raw material natural gas; the rich liquor absorbing H2S is regenerated into barren liquor after passing through a multi-stage regeneration tower, and sulfide is reduced to form elemental sulfur at the same time; and the flash steam separated from the rich liquid is pressurized and then returns to a natural gas system to be reused. By means of the method, the high-pressure high-sulfur-content pilot production well vent gas can be treated and recycled, so that the high-pressure high-sulfur-content pilot production well vent gas reaches the natural gas product standard, and the problem of sulfur blockage in existing complex iron desulfurization can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of natural gas purification methods and relates to a small-scale high-sulfur natural gas desulfurization method. Background Art

[0002] The experience of selecting the desulfurization process for small-scale natural gas processing (less than 500,000 cubic meters / day) with medium and low sulfur content (undercurrent flow S<50t / d, especially S<10t / d) at home and abroad is as follows:

[0003] (1) The latent sulfur content is small (S < 0.1t / d), and the dry desulfurization process is the main one. In recent years, triazine solution desulfurization has also been used;

[0004] (2) The potential sulfur content is large (S ≥ 5t / d), and the amine desulfurization + sulfur recovery process is used;

[0005] (3) For medium potential sulfur content (0.1-5 t / d) between the above two, liquid phase redox process is used, such as complex iron, biological desulfurization direct desulfurization process, etc.

[0006] At present, wellhead desulfurization mostly adopts dry desulfurization and complex iron desulfurization processes. Dry desulfurization uses a vertical packed desulfurization tower filled with solid desulfurizers, such as sponge iron, activated carbon, zinc oxide, etc. The process is simple and the equipment is small, but the waste desulfurizer after replacement is difficult to handle and the operating cost is high. Therefore, this method is mostly used for natural gas desulfurization with a potential sulfur content of less than 100kg / d. The desulfurization tower of the complex iron desulfurization process adopts drum absorption, which has low absorption efficiency and results in a large tower diameter. Under low-pressure conditions, the impact on investment is small, but for high-pressure natural gas equipment, the investment will increase a lot, and the sulfur element particles formed by the complex iron desulfurization process are large, which is easy to cause sulfur plugging problems.

[0007] Therefore, it is necessary to further research and develop the desulfurization process and design a new desulfurization process that can not only solve the sulfur plugging problem existing in complex iron desulfurization but also meet the economic efficiency. Summary of the invention

[0008] The purpose of the present invention is to provide a desulfurization method suitable for small-scale high-sulfur natural gas. The method can not only process and recover the vented air from high-pressure and high-sulfur test wells to meet the natural gas product standards, but also solve the sulfur plugging problem of existing complex iron desulfurization.

[0009] The technical scheme adopted by the present invention is a small-scale high-sulfur natural gas desulfurization method, which adopts an iron ion / biological bacteria mixed solution as a desulfurizer. The raw natural gas is countercurrently contacted with the iron ion / biological bacteria mixed solution in a desulfurization tower, and undergoes multi-stage desulfurization to remove H2S in the raw natural gas; the rich liquid after absorbing H2S is regenerated into a lean liquid after passing through a multi-stage regeneration tower, and the sulfide is reduced to form elemental sulfur; the flash gas separated from the rich liquid is pressurized and returned to the natural gas system for reuse.

[0010] The present invention is also characterized in that:

[0011] Small-scale high-sulfur natural gas desulfurization method, the specific process is:

[0012] a. Desulfurization process

[0013] The raw natural gas comes from the wellhead and is initially separated by the raw gas gas-liquid separator. The sulfur-containing wastewater is sent to the sewage treatment facility for treatment, and the raw gas enters the desulfurization tower for desulfurization. The desulfurization tower adopts a multi-stage series mode. In the tower, the sulfur-containing natural gas contacts with the iron ion / biological bacteria mixed solution from bottom to top in countercurrent. After multi-stage desulfurization, almost all H2S in the gas is absorbed and removed by the mixed solution to obtain sulfur-free natural gas.

[0014] b. Regeneration process

[0015] The iron ion / biological bacteria mixed solution absorbs H2S in the desulfurization tower and becomes rich liquid. The rich liquid is discharged from the bottom of the desulfurization tower and enters the flash tank through the pressure reduction section of the solution circulation turbine pump. The rich liquid enters the regeneration tower after the pressure is reduced in the flash tank. The regeneration tower adopts a multi-stage series mode. After multi-stage regeneration, the iron ion / biological bacteria mixed solution is completely regenerated and the ability to absorb hydrogen sulfide is restored.

[0016] C. Flash gas recovery process

[0017] The flash gas coming out of the flash tank enters the flash gas absorption tower, and then passes through the flash gas inlet separator, flash gas compressor, flash gas air cooler and flash gas outlet separator before returning to the natural gas system.

[0018] The desulfurization tower adopts a packed tower and uses stainless steel brushed filler.

[0019] The specific process of rich liquid multi-stage regeneration is:

[0020] The rich liquid of the iron ion / biological bacteria mixed solution enters the ejector at the top of the first regeneration tower, mixes with the air blown in by the air blower in the first regeneration tower, and begins to undergo regeneration reaction under the joint action of the iron ion / biological bacteria catalyst; the regenerated solution flows by gravity to the semi-lean liquid tank, is pressurized by the enhanced regeneration pump, enters the ejector at the top of the second regeneration tower, and is mixed with the blown air in the second regeneration tower for regeneration.

[0021] During the regeneration process, different regeneration tower stages are set according to the H2S concentration in the acid gas and the lean liquid regeneration effect to be achieved.

[0022] A water replenishment process is set up before the regeneration air enters the regeneration tower, on the one hand to reduce the temperature of the regeneration air, on the other hand to replenish water to the system.

[0023] The specific process of sulfur formation during the regeneration process is:

[0024] The sulfide in the rich liquid is oxidized into elemental sulfur in the regeneration tower. The elemental sulfur is suspended in the upper layer of the regeneration tower in the form of foam. The sulfur foam then flows out of the foam overflow port of the regeneration tower and enters the sulfur foam tank. It is then pumped into the plate and frame filter by the sulfur foam pump to generate sulfur after filtration.

[0025] The beneficial effects of the present invention are:

[0026] (1) The method of the present invention adopts a double-tower desulfurization process with a mixed solution of iron ions and biological bacteria, and the product gas index reaches H2S less than 6 mg / m 3 ;

[0027] (2) The sulfur element produced by the iron ion / biological bacteria mixed solution double-tower desulfurization process used in the method of the present invention has a small diameter, which can solve the sulfur plugging problem in the complex iron direct desulfurization process;

[0028] (3) The method of the present invention uses a mixed solution of iron ions / biological bacteria as a desulfurizing agent, and no solid sulfur is generated in the absorption stage. Compared with the traditional complex iron direct desulfurization process, a packed tower or plate tower with higher absorption efficiency can be selected, and less investment is required when treating high-concentration hydrogen sulfide;

[0029] (4) The desulfurization and regeneration in the method of the present invention can be carried out in multiple stages in series according to actual conditions, and can meet the desulfurization requirements of raw gas with different processing volumes and different H2S contents and different natural gas products;

[0030] (5) The method of the present invention processes and recovers the flash gas, and the flash gas after processing can directly enter the purified gas system, which can reduce air pollution and increase the commercial rate of natural gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the desulfurization process in the method of the present invention;

[0032] Figure 2 It is a schematic diagram of the regeneration process in the method of the present invention;

[0033] Figure 3 It is a schematic diagram of the flash gas recovery process in the method of the present invention.

[0034] In the figure, 1. raw gas gas-liquid separator, 2. wet purified gas gas-liquid separator, 3. primary desulfurization tower, 4. secondary desulfurization tower, 5. tertiary desulfurization tower, 6. primary regeneration tower, 7. semi-lean liquid tank, 8. enhanced regeneration pump, 9. secondary regeneration tower, 10. lean liquid tank, 11. solution circulation turbine pump, 12. sulfur foam tank, 13. sulfur foam pump, 14. plate and frame filter, 15. flash gas absorption tower, 16. flash gas inlet separator, 17. flash gas compressor, 18. flash gas air cooler, 19. flash gas outlet separator, 20. flash tank. DETAILED DESCRIPTION

[0035] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] The small-scale high-sulfur natural gas desulfurization method of the present invention uses an iron ion / biological bacteria mixed solution to perform wellhead desulfurization on a high-sulfur test well. The basic principle of desulfurization is:

[0037] During the operation of desulfurization technology, there are three processes: absorption, regeneration and biochemical degradation.

[0038] For the convenience of expression, DDS~Fe is used to represent the iron ion / biological bacteria ligand, sulfur-loving oxygen-consuming heat-resistant and alkali-resistant bacteria are represented by ⊙, and organic sulfur is represented by R~S. The basic principle can be expressed by the following reaction formula:

[0039] ①Absorption reaction

[0040] When sulfur-containing gas comes into contact with an alkaline aqueous solution (desulfurization solution) containing bacteria and DDS-Fe catalyst, the following reaction occurs:

[0041] H2S+DDS~Fe→DDS~Fe…(H2S)

[0042] R~S+DDS~Fe→DDS~Fe…(R~S)

[0043] H2S+⊙→⊙…(H2S)

[0044] R-S+⊙→⊙…(R~S)

[0045] ②Regeneration reaction

[0046] The desulfurized solution that has absorbed sulfide is called "rich solution". When the "rich solution" is regenerated, the bacteria metabolize the sulfide into elemental sulfur under the action of oxygen supplied by the DDS-Fe catalyst. The regeneration reaction is as follows:

[0047] DDS~Fe…(H2S)+1 / 2O2(air)→S+H2O+DDS~Fe

[0048] DDS~Fe…(R~S)+1 / 2O2(air)+4H+→S+R+H2O+DDS~Fe

[0049] DDS~Fe+1 / 2O2(air)→DDS~Fe…O

[0050] ⊙…(H2S)+DDS~Fe…O→S+H2O+⊙+DDS~Fe

[0051] ⊙…(R~S)+DDS~Fe…O+4H+→S+R+H2O+⊙+DDS~Fe

[0052] The "rich liquid" after air oxidation regeneration is transformed into "lean liquid", and the "lean liquid" is recycled.

[0053] ③ Biochemical degradation process

[0054] With the assistance of DDS-Fe ligands, sulfur-loving, oxygen-consuming, heat-resistant and alkali-resistant bacteria can decompose a small amount of insoluble iron salts such as FeCO3, Fe(OH)2, and FeS produced during the absorption and regeneration process, returning them to the iron-alkali solution, ensuring that various forms of DDS-Fe exist stably in the solution. The degradation reaction is as follows:

[0055] ⊙+FeCO3→⊙~FeO+CO2

[0056] ⊙+FeS→⊙~FeS

[0057] ⊙+Fe(OH)2→⊙~Fe(OH)2

[0058] ⊙~FeO+DDS→⊙~O+DDS~Fe2+

[0059] ⊙~FeS+DDS→⊙~S+DDS~Fe2+

[0060] ⊙~Fe(OH)2+DDS→⊙~O+DDS~Fe2++H2O

[0061] ⊙~O+⊙~S+H2O→2⊙+2OH-+S

[0062] The method of the present invention uses a mixed solution of iron ions / biological bacteria as a desulfurizing agent to desulfurize natural gas. The specific process flow is as follows:

[0063] (1) Desulfurization absorption part

[0064] ①Natural gas process

[0065] like Figure 1As shown, the raw natural gas comes from the wellhead and is initially separated by the raw gas gas-liquid separator 1. The sulfur-containing wastewater is sent to the sewage treatment facility for treatment, and the raw gas enters the desulfurization tower for desulfurization. In the tower, the sulfur-containing natural gas contacts the iron ion / biological bacteria mixed solution from bottom to top in countercurrent. After multi-stage desulfurization, 50% H2S is removed at each stage, and almost all H2S in the gas is absorbed and removed by the mixed solution. The desulfurization tower adopts a multi-stage series mode, such as Figure 1 The primary desulfurization tower 3, the secondary desulfurization tower 4, and the tertiary desulfurization tower 5 are connected in series to ensure the quality index of the purified gas. The gas pressure drop in a single tower is less than 800 Pa. The wet purified gas out of the tower is separated by the wet purified gas gas-liquid separator 2 and then sent to the dehydration device.

[0066] ②Rich liquid process

[0067] like Figure 2 As shown, the mixed solution absorbs H2S in the desulfurization tower to become rich liquid, which is discharged from the bottom of the desulfurization tower and enters the flash tank 20 through the pressure reduction section of the solution circulation turbine pump 11. The CH4, CO2 and trace H2S dissolved in the solution are decompressed and analyzed, and then go to the flash gas absorption tower 15 for treatment. The rich liquid is depressurized to 400kPa and enters the first regeneration tower 6 to ensure the residence time of the desulfurized rich liquid in the regeneration tower. The regeneration air is blown in by the air blower, and the desulfurized rich liquid is fully in contact with the air in the regeneration tower to complete the regeneration. The regeneration tower adopts a multi-stage series method, such as Figure 2 The primary regeneration tower 6 and the secondary regeneration tower 9 are connected in series to ensure the regeneration effect of the lean liquid, and the completely regenerated lean liquid enters the lean liquid tank 10. At this point, the DDS-Fe solution is completely regenerated and the ability to absorb hydrogen sulfide is restored.

[0068] ③Lean solution process

[0069] After regeneration, the rich liquid becomes a mixed solution of iron ions / biological bacteria (lean liquid). The lean liquid enters the heat exchanger from the lean liquid tank 10 through the boosting section of the solution circulation turbine pump 11. After heat exchange with cooling water, the temperature is reduced to 20°C and enters the desulfurization tower for recycling.

[0070] ④Flash gas recovery process

[0071] The flash gas coming out of the flash tank 20 enters the flash gas absorption tower 15, and the flash gas with a temperature of 56°C and a pressure of 400 kPa comes out. After passing through the flash gas inlet separator 16, the pressure is increased to 5.8 MPa by the flash gas compressor 17, and then separated by the flash gas air cooler 18 and the flash gas outlet separator 19, it returns to the natural gas system.

[0072] (2) Desulfurization regeneration part

[0073] ① Regeneration process

[0074] The rich solution of the iron ion / biological bacteria mixed solution enters the ejector at the top of the regeneration tower, mixes with the air blown in by the air blower in the first-stage regeneration tower 6, and begins to undergo a regeneration reaction under the combined action of the iron ion / biological bacteria catalyst. A water replenishment process is set before the regeneration air enters the regeneration tower, which can reduce the temperature of the regeneration air and replenish water to the system.

[0075] The regenerated solution flows by gravity through the liquid level regulator to the semi-lean liquid tank 7, is pressurized by the enhanced regeneration pump 8, enters the ejector at the top of the secondary regeneration tower 9, and is mixed with the blown air in the secondary regeneration tower 9 for regeneration.

[0076] In this way, different stages are set according to the H2S concentration in the acid gas and the effect of ensuring the regeneration of the lean liquid.

[0077] ②Sulfur molding process

[0078] The sulfide in the rich liquid is oxidized into elemental sulfur in the regeneration tower, and the elemental sulfur is suspended in the upper layer of the regeneration tower in the form of foam. The sulfur foam then flows out of the foam overflow port of the regeneration tower and enters the sulfur foam tank 12, and is then sent to the plate and frame filter 14 for filtration by the sulfur foam pump 13. The moisture content of the sulfur paste byproduct obtained by filtration is not more than 20%, and is then entrusted to a professional company for treatment as solid waste.

[0079] The method of the present invention adopts a double-tower desulfurization process of iron ion / biological bacteria mixed solution, which solves the problems of high cost of traditional dry desulfurization and sulfur plugging and low efficiency of complex iron direct desulfurization. At the same time, the series number of desulfurization towers can be flexibly changed to meet the desulfurization requirements of raw gas with different processing gas volumes and different H2S contents and different natural gas products, and also ensure the environmental protection requirements of tail gas emissions. Not only does it increase the applicability of desulfurization of high-sulfur natural gas at the natural gas wellhead, but also in the field of natural gas purification, its engineering investment and operating costs are also lower than the commonly used complex iron direct desulfurization technology and the "alcoholamine method + Super Claus sulfur recovery + SCOT tail gas treatment" combined process.

[0080] The present invention adopts the iron ion / biological bacteria mixed solution double tower desulfurization process to produce natural gas products according to different product index requirements, which can meet the most stringent product index requirements, that is, H2S content: ≤6mg / m 3 , total sulfur content (in terms of sulfur): ≤20mg / m 3 The H2S content in the exhaust gas meets the "Emission Standards of Air Pollutants for Onshore Petroleum and Natural Gas Production Industry" (GB39728-2020), which is less than 10 mg / m 3 The sulfur produced meets the requirements of the Ministry of Industry and Information Technology, and has a purity of more than 65%. It can be connected to the downstream sulfur purification device to produce sulfur products, and can also be exported to sulfuric acid plants, fertilizer plants and pesticide plants.

[0081] Example 1

[0082] Raw natural gas (10×10 4 m 3 / d, H2S content 80g / m 3 ) enters the raw gas gas-liquid separator 1 to further separate the water entrained in the gas. After the raw gas passes through the separator, it enters the tower from the lower part of the primary desulfurization tower 3. The gas stays in the tower for 1 to 2 minutes, and the gas pressure drop in a single tower is less than 800Pa. After the raw gas passes through the primary desulfurization tower 3, 50% of the H2S in the gas is absorbed by the desulfurization liquid (the H2S content of the raw gas remains 50%). The absorption rate of each stage of desulfurization can be adjusted by adjusting the flow rate of the desulfurization liquid. After the raw gas passes through the primary desulfurization tower 3, it flows out from the top of the primary desulfurization tower 3 and enters from the bottom of the secondary desulfurization tower 4 for the second stage of desulfurization. The structural parameters and design form of the secondary desulfurization tower 4 are the same as those of the primary desulfurization tower 3. After the raw gas passes through the secondary desulfurization tower 4, 50% of the H2S is absorbed by the desulfurization liquid (the H2S content of the raw gas remains 25%). The raw gas is then circulated through the above method and enters the third stage (H2S content remaining 12.6%), fourth stage (H2S content remaining 6.25%), and fifth stage desulfurization towers (H2S content remaining 0%) in sequence. The desulfurization liquid injection flow rate of each stage is 80m 3 / h.

[0083] The DDS-Fe solution (rich liquid) that has absorbed hydrogen sulfide and organic sulfur enters the primary regeneration tower 6, and the desulfurized liquid is designed to stay in the regeneration tower for 20 minutes. The regeneration tower is self-priming air, and the desulfurized liquid rich liquid is fully in contact with the air in the regeneration tower to complete the regeneration. The regenerated solution enters the semi-lean liquid tank 7, and the regeneration capacity reaches 90%. The solution enters the secondary regeneration tower 9 through the enhanced regeneration pump 8, and the fully regenerated lean liquid enters the lean liquid tank 10.

[0084] Example 2

[0085] Raw natural gas (5×10 4 m 3 / d, H2S content 100g / m 3 , operating pressure 5.5Mpa) enters the raw gas gas-liquid separator 1 to further separate the water entrained in the gas. After the raw gas passes through the separator (removing 3-5um droplets), it enters the tower from the lower part of the primary desulfurization tower 3. After passing through the primary desulfurization tower 3, 60% of the H2S in the gas is absorbed by the desulfurization liquid and flows out from the top of the primary desulfurization tower 3. The absorption rate of each stage of desulfurization can be adjusted by adjusting the flow rate of the desulfurization liquid. It passes through the secondary (raw gas H2S content remains 25%), the third (H2S content remains 12.6%), the fourth (H2S content remains 6.25%), and the fifth desulfurization tower (H2S content remains 0%) in turn. The desulfurization liquid injection flow rate of each stage is 50m 3 / h. The rest is the same as in Example 1.

[0086] Example 3

[0087] Raw natural gas (5×10 4 m 3 / d, H2S content 100g / m 3 , operating pressure 5.5Mpa) enters the raw gas gas-liquid separator 1 to further separate the water entrained in the gas. After the raw gas passes through the separator (removes 3-5um droplets), it enters the tower from the lower part of the primary desulfurization tower 3. After passing through the primary desulfurization tower 3, 70% of the H2S in the gas is absorbed by the desulfurization liquid (the H2S content of the raw gas remains 30%), and flows out from the top of the primary desulfurization tower 3, and passes through the secondary (H2S content remains 10%), the tertiary (H2S content remains 3%), and the quaternary desulfurization tower (H2S content remains 0%) in turn. The desulfurization liquid injection flow rate of each stage is 80m 3 / h. The rest is the same as in Example 1.

[0088] Example 4

[0089] Raw natural gas (10×10 4 m 3 / d, H2S content 80g / m 3 ) enters the raw gas gas-liquid separator 1 to further separate the water entrained in the gas. After the raw gas passes through the separator (removing 3-5um droplets), it enters the tower from the lower part of the primary desulfurization tower 3. After passing through the primary desulfurization tower 3, 40% of the H2S in the gas is absorbed by the desulfurization liquid (the H2S content of the raw gas remains 60%), and flows out from the top of the primary desulfurization tower 3, and passes through the secondary (H2S content remains 36%), the third (H2S content remains 21.6%), the fourth desulfurization tower (H2S content remains 12.96%), the fifth desulfurization tower (H2S content remains 7.776%), and the sixth desulfurization tower (H2S content remains 0%) in turn. The desulfurization liquid injection flow rate of each stage is 50m 3 / h. The rest is the same as in Example 1.

Claims

1. A small-scale high-sulfur natural gas desulfurization method, characterized in that: A mixed solution of iron ions and biological bacteria is used as a desulfurizer. The raw natural gas is countercurrently contacted with the mixed solution of iron ions and biological bacteria in the desulfurization tower, and H2S in the raw natural gas is removed through multi-stage desulfurization. The rich liquid after absorbing H2S is regenerated into lean liquid after passing through a multi-stage regeneration tower, and the sulfide is reduced to form elemental sulfur. The flash gas separated from the rich liquid is pressurized and returned to the natural gas system for reuse.

2. The small-scale high-sulfur natural gas desulfurization method according to claim 1, characterized in that: The specific process is: a. Desulfurization process The raw natural gas comes from the wellhead and is initially separated by the raw gas gas-liquid separator (1). The sulfur-containing wastewater is sent to the wastewater treatment facility for treatment. The raw gas enters the desulfurization tower for desulfurization. The desulfurization tower adopts a multi-stage series mode. In the tower, the sulfur-containing natural gas contacts with the iron ion / biological bacteria mixed solution from bottom to top in countercurrent. After multi-stage desulfurization, almost all H2S in the gas is absorbed and removed by the mixed solution, and sulfur-free natural gas is obtained. b. Regeneration process After the iron ion / biological bacteria mixed solution absorbs H2S in the desulfurization tower, it becomes a rich liquid. The rich liquid is discharged from the bottom of the desulfurization tower and enters the flash tank (20) through the pressure reduction section of the solution circulation turbine pump (11). After the pressure is reduced in the flash tank (20), the rich liquid enters the regeneration tower. The regeneration tower adopts a multi-stage series mode. After the multi-stage regeneration, the iron ion / biological bacteria mixed solution is completely regenerated and the ability to absorb hydrogen sulfide is restored. C. Flash gas recovery process The flash gas from the flash tank (20) enters the flash gas absorption tower (15), passes through the flash gas inlet separator (16), the flash gas compressor (17), the flash gas air cooler (18) and the flash gas outlet separator (19), and then returns to the natural gas system.

3. The small-scale high-sulfur natural gas desulfurization method according to claim 1 or 2, characterized in that: The desulfurization tower is a packed tower and uses stainless steel wire drawing packing.

4. The small-scale high-sulfur natural gas desulfurization method according to claim 1 or 2, characterized in that: The specific process of rich liquid multi-stage regeneration is: The rich solution of the iron ion / biological bacteria mixed solution enters the ejector at the top of the primary regeneration tower (6), is mixed with the air blown in by the air blower in the primary regeneration tower (6), and begins to undergo a regeneration reaction under the combined action of the iron ion / biological bacteria catalyst; the regenerated solution flows by gravity to the semi-lean liquid tank (7), is pressurized by the enhanced regeneration pump (8), enters the ejector at the top of the secondary regeneration tower (9), and is mixed with the blown air in the secondary regeneration tower (9) for regeneration.

5. The small-scale high-sulfur natural gas desulfurization method according to claim 4, characterized in that: During the regeneration process, different regeneration tower stages are set according to the H2S concentration in the acid gas and the lean liquid regeneration effect to be achieved.

6. The small-scale high-sulfur natural gas desulfurization method according to claim 4, characterized in that: A water replenishment process is set up before the regeneration air enters the regeneration tower, on the one hand to reduce the temperature of the regeneration air, on the other hand to replenish water to the system.

7. The small-scale high-sulfur natural gas desulfurization method according to claim 1 or 2, characterized in that: The specific process of sulfur formation during the regeneration process is: The sulfide in the rich liquid is oxidized into elemental sulfur in the regeneration tower. The elemental sulfur is suspended in the upper layer of the regeneration tower in the form of foam. Then, the sulfur foam flows out from the foam overflow port of the regeneration tower and enters the sulfur foam tank (12). Then, the sulfur foam pump (13) sends the sulfur foam to the plate and frame filter (14) for filtration, and sulfur is generated after filtration.

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