Sulfur-containing tail gas emission reduction system and method for low-temperature Claus sulfur recovery device

Abstract

The invention discloses a sulfur-containing tail gas emission reduction system and method for a low-temperature Claus sulfur recovery device. The sulfur-containing tail gas emission reduction system comprises an incinerator connected to a tail gas exhaust port of the low-temperature Claus sulfur recovery device. The gas outlet end of the incinerator is connected with two oxidation catalytic reactors which are arranged in parallel, and outlets of the two oxidation catalytic reactors are respectively connected with a primary Claus reactor and a purified flue gas outlet of the low-temperature Claus sulfur recovery device through pipelines; the oxidation catalytic reactor is also connected with a reducing gas source; incinerator tail gas is introduced into one oxidation catalytic reactor to be in an oxidation adsorption state; and reducing gas is introduced into the other oxidation catalytic reactor to be in a reduction regeneration state. According to the sulfur tail gas emission reduction system and method, the flue gas sulfur dioxide emission concentration in the production process of low-temperature Claus processes such as CBA, CPS and MCRC sulfur recovery devices can be smaller than 50 mg / m < 3 > and is far lower than the lowest limit value of 400 mg / m < 3 > required by the national standard in the natural gas industry.

Description

Technical Field

[0001] The present invention relates to the technical field of sulfur recovery, and in particular, to a sulfur-containing tail gas emission reduction system and method for a low-temperature Claus sulfur recovery device. Background Art

[0002] In the processing of sulfur-containing crude oil, natural gas, coal, etc., sulfides will not only cause poisoning of precious metal catalysts in the production process, corrosion of pipelines and equipment, but also the un-recovered sulfides will pollute the atmospheric environment. In order to further reduce the emission of sulfur-containing pollutants, in the processing of sulfur-containing gases, the hydrogen sulfide is usually removed by an amine desulfurization device or a hydrogenation device, or the organic sulfur is hydrogenated and converted into hydrogen sulfide and then absorbed, so as to achieve the purpose of removing sulfides. The hydrogen sulfide regenerated is usually used to recover sulfur elements by the Claus process. Generally, large sulfur recovery devices use conventional two-stage Claus or three-stage Claus with supporting tail gas treatment devices such as reduction absorption for sulfur resource recovery. In the natural gas industry and other industries, due to the low latent sulfur content in the gas, the sulfur recovery device usually has a small scale, a low total emission, and a low hydrogen sulfide concentration in the sour gas. Therefore, the low-temperature Claus process is often used to recover sulfides.

[0003] At present, during the normal production of the sulfur recovery device using the low-temperature Claus process in natural gas purification plants, the mass concentration of sulfur dioxide in the flue gas of the sulfur recovery device is 3000 - 5000 mg / m 3 , and the instantaneous mass concentration of sulfur dioxide emissions during the adsorption and regeneration switching can reach tens of thousands of mg / m 3 , resulting in waste of sulfur resources and environmental hazards. With the rapid development of the economic society, the awareness of resource recycling and protection of the atmospheric environment has been rapidly improved. It is required that the emission concentration of natural gas purification plants with a processing scale greater than 200 t / d is less than or equal to 400 mg / m 3 , and the SO2 emission concentration of those less than or equal to 200 t / d is less than or equal to 800 mg / m 3 .

[0004] At present, in order for the sulfur dioxide in the flue gas of the sulfur recovery device of such a process to meet the emission standards, in addition to upgrading the catalyst with better performance in the reactor, a tail gas treatment device needs to be equipped. Currently, there are four process methods available: reduction absorption method, oxidation absorption method, alkali solution washing method, and sulfuric acid production method.

[0005] The above four methods can all solve the problem of the sulfur dioxide in the flue gas of the sulfur recovery device using the low-temperature Claus process meeting the emission standards, but there are still certain deficiencies in the four methods in terms of investment costs, process flow, and generation of secondary pollutants during the production process.

[0006] The prior art has at least the following problems:

[0007] (1) If a low-temperature Claus process sulfur recovery unit is equipped with a reduction absorption tail gas treatment unit, ① the sulfur dioxide emission in the flue gas can only be reduced to 400 mg / m 3 limit value, and it is very difficult to further reduce the emission; ② the reduction absorption process has a long process flow and many equipment. It not only requires a supporting hydrogenation hydrolysis catalyst, but also a highly efficient selective desulfurization solvent under normal pressure; ③ ammonia water or 30% sodium hydroxide needs to be added during the production process to adjust the pH of the quench tower, and acidic wastewater is generated during the production process; ④ sulfur blockage caused by incomplete hydrogenation is likely to occur from the hydrogenation reactor to the outlet of the quench tower, and the sulfur dioxide in the flue gas increases due to the fact that carbonyl sulfide cannot be absorbed in the atmospheric pressure absorption tower due to incomplete hydrolysis; ⑤ side reactions during the hydrogenation hydrolysis reaction process generate secondary pollutants such as sulfur, methanethiol, and ethanethiol due to the decrease in the inlet temperature of the hydrogenation reactor, increasing the sulfur dioxide emission concentration in the flue gas.

[0008] (2) If a low-temperature Claus process sulfur recovery unit is equipped with an alkali liquor washing method device, ① 30% sodium hydroxide solution is used as the absorbent to absorb sulfur dioxide, and the alkali liquor consumption per unit of sulfur dioxide absorption is large; ② waste solids such as alkali residues are generated during the production process; ③ high-salt wastewater is generated during the production process; ④ an evaporation crystallization device needs to be supported, and the purity of the generated sulfates and sulfites is difficult to meet the industrial standard requirements.

[0009] (3) If a low-temperature Claus process sulfur recovery unit is equipped with an oxidation absorption method device, ① the process flow is relatively long and there are many cold heat exchange equipment; ② high requirements for equipment materials, and some equipment materials require above alloy steel; ③ concentrated sulfuric acid storage tanks and sodium hydroxide solution storage tanks need to be set in the production device area for pH adjustment during the production process, otherwise the sulfur dioxide absorption effect will be affected; ④ high-salt wastewater is generated, and the existing sewage treatment scale and methods cannot handle it.

[0010] (4) If a low-temperature Claus process sulfur recovery unit is equipped with an acid-making device, ① the process flow is long and there are many equipment; ② high requirements for equipment and pipeline materials; ③ the production environment has strong operational risks for personnel due to the presence of SO3 and sulfuric acid; ③ acidic wastewater is generated and needs to be supported by an alkali liquor neutralization facility for treatment.

[0011] Therefore, for the problem of sulfur dioxide emission reduction in the tail gas of the low-temperature Claus process sulfur recovery unit, there is currently no solution with a simple process and operation, low investment cost, and better economy.

[0012] In view of this, the present application is specifically proposed. Summary of the Invention

[0013] To solve the above problems, the object of the present invention is to provide a sulfur-containing tail gas emission reduction system and method for a low-temperature Claus sulfur recovery device, which has a shorter process, fewer equipment, does not add chemicals, does not discharge waste water or generate alkali residues, and can recover sulfur resources while achieving the up-to-standard emission of the tail gas of the low-temperature Claus process sulfur recovery device.

[0014] The present invention is achieved through the following technical solutions:

[0015] In the first aspect, the present invention provides a sulfur-containing tail gas emission reduction system for a low-temperature Claus sulfur recovery device, including an incinerator connected to the tail gas discharge port of the low-temperature Claus sulfur recovery device;

[0016] The outlet end of the incinerator is connected to two parallel oxidation catalytic reactors, and the outlets of the two oxidation catalytic reactors are respectively connected to the first-stage Claus reactor and the purified flue gas discharge port of the low-temperature Claus sulfur recovery device through pipelines; a reducing gas source is also connected to the oxidation catalytic reactor;

[0017] In one oxidation catalytic reactor, the incinerator tail gas is introduced in an oxidation adsorption state to adsorb sulfur dioxide in the incinerator tail gas;

[0018] In the other oxidation catalytic reactor, reducing gas is introduced in a reduction and regeneration state to reduce and regenerate the adsorbed sulfur dioxide and return it to the inlet of the first-stage Claus reactor of the low-temperature Claus sulfur recovery device.

[0019] In a specific embodiment, the oxidation catalytic reactor is filled with an oxidation catalytic adsorbent, and the oxidation catalytic adsorbent is a granular catalyst formed by taking aluminum hydroxide as the main material, metal oxide as the auxiliary material, organic solvent and water as the solvent and by a compression method.

[0020] In a specific embodiment, the main material of aluminum hydroxide is prepared by subjecting aluminum hydroxide to rapid dehydration, pulverization, hydrothermal treatment, and microwave oscillation treatment, and the frequency of the microwave oscillation treatment used is 300 MHz to 300 GHz, and the treatment time is 4 to 8 hours.

[0021] In a specific embodiment, the oxidation catalytic reactor is a vertical fixed-bed reactor, and the oxidation catalytic adsorbent is filled in the middle area of the reactor, and fillers for supporting and dispersing heat are filled above and below the oxidation catalytic adsorbent bed.

[0022] In a specific embodiment, sulfur dioxide detectors are provided at the outlets of the two oxidation catalytic reactors, and two parallel sulfur dioxide detectors are provided on the main pipe of the purified flue gas at the outlets of the two oxidation catalytic reactors.

[0023] In a specific embodiment, two oxidation catalytic reactors use pneumatic switching valves to achieve the switching between the oxidation adsorption state and the reduction regeneration state. The switching time point is based on the sulfur dioxide concentration detected by a sulfur dioxide analyzer installed on the main pipe of the purified flue gas at the outlet of the oxidation catalytic reactor and the set value in the programmed switching procedure. In the programmed system procedure, it is set that when the concentrations detected by the two sulfur dioxide analyzers both reach 50 mg / m 3 When this occurs, the signal will be transmitted to the program to perform the automatic operation of switching the inlet valve of the reactor.

[0024] In a specific embodiment, the reducing gas source includes methane and nitrogen, which are from natural gas.

[0025] In a specific embodiment, the composition of the reducing gas source is 80 - 90% nitrogen and 10 - 20% methane.

[0026] In a specific embodiment, the ratio of sulfur dioxide, hydrogen sulfide to sulfur vapor in the sulfur-containing compounds generated during reduction regeneration is 6:3:1.

[0027] In a second aspect, the present invention also provides a method for reducing sulfur-containing tail gas emissions in a low-temperature Claus sulfur recovery unit, based on the above sulfur-containing tail gas emission reduction system, including the following steps:

[0028] (1) Feed the sulfur-containing tail gas of the low-temperature Claus sulfur recovery unit into an incinerator, burn it with air and fuel gas, and convert it into a gas mixture of sulfur dioxide and non-sulfur compounds, and control the oxygen content in the mixed flue gas after combustion to be 2% - 5%;

[0029] (2) Feed the mixed flue gas into a reactor containing an oxidation catalytic adsorbent, and sulfur dioxide and oxygen in the flue gas undergo an oxidation catalytic reaction under the action of a catalyst to generate sulfates and sulfites and adsorb on the catalyst, and use the oxidation adsorption method to remove the sulfur dioxide generated by the incinerator;

[0030] (3) After the reactor has reacted for a certain period of time, feed a reducing gas into the reactor containing the oxidation catalytic adsorbent, regenerate sulfur dioxide with the reducing gas and return it to the inlet of the first-stage Claus reactor of the low-temperature Claus sulfur recovery unit.

[0031] The sour gas containing hydrogen sulfide is burned in a combustion furnace with air added, and part of it is converted into sulfur dioxide. The unreacted hydrogen sulfide reacts with sulfur dioxide in the combustion furnace under high-temperature conditions to undergo the Claus reaction. Then, the heat in the process gas is recovered through a waste heat boiler to generate medium-pressure steam, which enters the steam system. After cooling, the process gas is preheated and then sent to a conventional Claus reactor to continue the Claus reaction for sulfur recovery. The process gas coming out of the reactor enters the low-temperature Claus reaction system, where the Claus reaction occurs around the dew point. Generally, 2 to 4 reactors are set up. The process includes CBA, CPS, and MCRC. Through the Claus reaction at about 127°C and the thermal regeneration at about 280°C to distill out the sulfur generated by the low-temperature reaction, the purpose of improving the sulfur recovery rate is achieved. The tail gas coming out of the low-temperature Claus usually contains relatively high levels of hydrogen sulfide, sulfur dioxide, carbonyl sulfide, and carbon disulfide.

[0032] The tail gas of the low-temperature Claus process that has not been recovered above is mixed with air and burned in the incinerator of the present invention at 600 - 800°C to be converted into sulfur dioxide, ensuring the complete conversion of hydrogen sulfide, carbonyl sulfide, and carbon disulfide. The sulfur dioxide-containing flue gas at 200 - 350°C that comes out of the incinerator and has its heat recovered has a sulfur dioxide concentration of 3000 - 5000 mg / m 3 , and then it is introduced into the system of the present invention for oxidative catalytic reaction to remove sulfur dioxide to 50 mg / m 3 or less. Therefore, the purified flue gas coming out of this system can be directly discharged into the atmosphere through a chimney.

[0033] The system of the present invention includes 2 parallel reactors filled with catalysts. The inlet and outlet pipelines of the reactors are equipped with several pneumatic switching valves. An on-line sulfur dioxide detector is set on the main pipe of the purified flue gas at the reactor outlet. The switching between the reaction and regeneration of the two oxidative catalytic reactors establishes a logical control relationship through the return value of the sulfur dioxide mass concentration signal detected by the sulfur dioxide detector programmed. It is set that when the sulfur dioxide detectors of both exceed 50 mg / m 3 , the automatic switching operation of adsorption and regeneration of the reactor is carried out.

[0034] Specifically, the oxidative catalytic reaction and catalytic reduction regeneration states of the 2 reactors can also be designed according to the flue gas flow rate and sulfur dioxide mass concentration of the sulfur recovery device of the low-temperature Claus process.

[0035] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0036] 1. The sulfur-containing tail gas emission reduction system and method for a low-temperature Claus sulfur recovery device provided by the embodiment of the present invention can achieve that the sulfur dioxide emission concentration of the flue gas in the production process of sulfur recovery devices of low-temperature Claus processes such as CBA, CPS, and MCRC is less than 50 mg / m 3, far lower than the minimum of 400 mg / m required by the national standard of the natural gas industry 3 limit value;

[0037] 2. A sulfur-containing tail gas emission reduction system and method for a low-temperature Claus sulfur recovery device provided by an embodiment of the present invention can be directly connected between the incinerator and the chimney of an existing low-temperature Claus process sulfur recovery device. The raw material comes from the incinerator of the existing device, and the purified flue gas after treatment is directly discharged through the chimney. The reducing gas comes from the factory common system, and the renovation workload is small;

[0038] 3. A sulfur-containing tail gas emission reduction system and method for a low-temperature Claus sulfur recovery device provided by an embodiment of the present invention has a short process flow, few equipment, no cold and heat exchange equipment, small floor area, and low investment cost. The production process is a gas-solid fixed bed reaction, and no chemicals need to be added to the system, and no wastewater or waste residue is generated;

[0039] 4. A sulfur-containing tail gas emission reduction system and method for a low-temperature Claus sulfur recovery device provided by an embodiment of the present invention. The catalyst regeneration gas volume is only 10% of the flue gas flow rate. The proportion of sulfur dioxide, hydrogen sulfide, and sulfur vapor in the regeneration gas is suitable for introducing into the Claus reactor for treatment, which does not affect the adjustment of other operating parameters of the sulfur recovery device, realizes sulfur cycle treatment, and reduces the emission of sulfur-containing gases;

[0040] 5. A sulfur-containing tail gas emission reduction system and method for a low-temperature Claus sulfur recovery device provided by an embodiment of the present invention. The oxidation catalytic adsorbent used can restore its catalytic activity through hot-state reducing gas regeneration treatment, and the catalyst can be recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, so they should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0042] Figure 1 It is a structural flow chart of a sulfur-containing tail gas emission reduction system provided by Embodiment 1 of the present invention. Both R1 and R2 are oxidation catalytic reactors, and V1, V2, V3, V4, V5, V6, V7, and V8 are pneumatic switching valves. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions thereof of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0044] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those of ordinary skill in the art that: the present invention may be practiced without these specific details. In other instances, well-known structures, circuits, materials, or methods have not been specifically described to avoid obscuring aspects of the present invention.

[0045] Throughout the specification, references to "one embodiment", "an embodiment", "one example", or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "one embodiment", "an embodiment", "one example", or "an example" throughout the specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and / or sub-combination in one or more embodiments or examples. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0046] In the description of the present invention, the orientation or positional relationships indicated by the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", "outer", etc. are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the scope of protection of the present invention.

[0047] Embodiment 1

[0048] As Figure 1 shown, a sulfur-containing tail gas emission reduction system for a low-temperature Claus sulfur recovery device provided by an embodiment of the present invention includes an incinerator connected to the tail gas discharge port of the low-temperature Claus sulfur recovery device;

[0049] The gas outlet end of the incinerator is connected to two oxidation catalytic reactors arranged in parallel. The outlets of the two oxidation catalytic reactors are respectively connected to the first-stage Claus reactor and the purified flue gas discharge port of the low-temperature Claus sulfur recovery device through pipelines; the oxidation catalytic reactor is also connected to a reducing gas source;

[0050] In one oxidation catalytic reactor, the incinerator tail gas is introduced in an oxidation adsorption state to adsorb sulfur dioxide in the incinerator tail gas;

[0051] In the other oxidation catalytic reactor, reducing gas is introduced in a reduction regeneration state to reduce and regenerate the adsorbed sulfur dioxide and return it to the inlet of the first-stage Claus reactor of the low-temperature Claus sulfur recovery device.

[0052] In a specific embodiment, the oxidation catalytic reactor is filled with an oxidation catalytic adsorbent, which is a granular catalyst formed by taking aluminum hydroxide as the main material, metal oxide as the auxiliary material, organic solvent and water as the solvent and by means of compression molding.

[0053] In a specific embodiment, the aluminum hydroxide main material is prepared by subjecting aluminum hydroxide to rapid dehydration, pulverization, hydrothermal treatment, and microwave oscillation treatment. The frequency of the microwave oscillation treatment used is 300 MHz to 300 GHz, and the treatment time is 4 to 8 hours.

[0054] In a specific embodiment, the oxidation catalytic reactor is a vertical fixed-bed reactor. The oxidation catalytic adsorbent is filled in the middle area of the reactor, and fillers for supporting and dispersing heat are filled above and below the oxidation catalytic adsorbent bed.

[0055] In a specific embodiment, sulfur dioxide detectors are provided at the outlets of two oxidation catalytic reactors. Two sulfur dioxide detectors connected in parallel are arranged on the main pipe of the purified flue gas at the outlets of the two oxidation catalytic reactors.

[0056] In a specific embodiment, two oxidation catalytic reactors use a pneumatic switching valve to achieve the switching between the oxidation adsorption state and the reduction regeneration state. The switching time point is based on the sulfur dioxide concentration detected by a sulfur dioxide analyzer arranged on the main pipe of the purified flue gas at the outlet of the oxidation catalytic reactor and the set value in the compiled switching program. In the compiled system program, it is set that when the concentrations detected by the two sulfur dioxide analyzers both reach 50 mg / m 3 ³, this signal will be transmitted to the program to execute the automatic operation of switching the inlet valve of the reactor.

[0057] In a specific embodiment, the reducing gas source includes methane and nitrogen, which are from natural gas.

[0058] In a specific embodiment, the composition of the reducing gas source is 80 - 90% nitrogen and 10 - 20% methane.

[0059] In a specific embodiment, the ratio of sulfur dioxide, hydrogen sulfide and sulfur vapor in the sulfur-containing compounds generated during reduction regeneration is 6:3:1.

[0060] The sour gas containing hydrogen sulfide is burned in a combustion furnace with air added, and part of it is converted into sulfur dioxide. The unreacted hydrogen sulfide reacts with sulfur dioxide in the combustion furnace under high-temperature conditions to undergo the Claus reaction. Then, the heat in the process gas is recovered through a waste heat boiler to generate medium-pressure steam, which enters the steam system. After cooling, the process gas is preheated and then sent to a conventional Claus reactor to continue the Claus reaction for sulfur recovery. The process gas coming out of the reactor enters a low-temperature Claus reaction system, where the Claus reaction occurs around the dew point. Generally, 2 to 4 reactors are set up. The process includes three types: CBA, CPS, and MCRC. Through the Claus reaction at about 127°C and the thermal regeneration at about 280°C to distill out the sulfur generated by the low-temperature reaction, the purpose of improving the sulfur recovery rate is achieved. The tail gas coming out of the low-temperature Claus usually contains relatively high concentrations of hydrogen sulfide, sulfur dioxide, carbonyl sulfide, and carbon disulfide.

[0061] The tail gas of the low-temperature Claus process that has not been recovered above is mixed with air and burned in the incinerator of the present invention at 600 - 800°C to be converted into sulfur dioxide, ensuring the complete conversion of hydrogen sulfide, carbonyl sulfide, and carbon disulfide. The sulfur dioxide-containing flue gas at 200 - 350°C that comes out of the incinerator and has its heat recovered has a sulfur dioxide concentration of 3000 - 5000 mg / m 3 , and then it is introduced into the system of the present invention for an oxidation catalytic reaction to remove sulfur dioxide to 50 mg / m 3 or less. Therefore, the purified flue gas coming out of this system can be directly discharged to the atmosphere through a chimney.

[0062] The system of the present invention includes two reactors filled with catalysts in parallel. The inlet and outlet pipelines of the reactors are equipped with several pneumatic switching valves. An on-line sulfur dioxide detector is set on the main pipe of the purified flue gas at the reactor outlet. The switching between the reaction and regeneration of the two oxidation catalytic reactors establishes a logical control relationship through the return value of the sulfur dioxide mass concentration signal detected by the sulfur dioxide detector in the programmed procedure. It is set that when the sulfur dioxide detectors of both exceed 50 mg / m 3 , the reactor automatically switches between adsorption and regeneration operations.

[0063] Specifically, according to the flue gas flow rate and sulfur dioxide mass concentration of the sulfur recovery device of the low-temperature Claus process, the oxidation catalytic reaction and catalytic reduction regeneration states of the two reactors are designed.

[0064] Example 2

[0065] A method for reducing sulfur-containing tail gas emissions from a low-temperature Claus sulfur recovery device provided by an embodiment of the present invention is based on the sulfur-containing tail gas emission reduction system described in Example 1 and includes the following steps:

[0066] (1) Feed the sulfur-containing tail gas from the low-temperature Claus sulfur recovery unit into the incinerator, burn it with air and fuel gas, convert it into a gas mixture of sulfur dioxide and non-sulfur compounds, and control the oxygen content of the mixed flue gas after combustion to be 2% - 5%;

[0067] (2) Feed the mixed flue gas into a reactor containing an oxidation catalytic adsorbent. Sulfur dioxide and oxygen in the flue gas undergo an oxidation catalytic reaction under the action of the catalyst to generate sulfates and sulfites and adsorb on the catalyst. Use the oxidation adsorption method to remove the sulfur dioxide generated by the incinerator. The sulfur dioxide concentration coming out of the reactor is less than 50 mg / m 3 and directly discharge it through the chimney;

[0068] (3) When the on-line sulfur dioxide detector set at the outlet of the reactor detects that the sulfur dioxide concentration is close to 50 mg / m 3 , transfer to another reactor for oxidation catalytic absorption of sulfur dioxide;

[0069] (4) Use methane and nitrogen gases to regenerate the reactor adsorbed with sulfur dioxide to produce a mixed gas of sulfur dioxide, hydrogen sulfide, and sulfur vapor, with a ratio of 6:3:1 for the three, and restore the catalyst performance of the reactor;

[0070] (5) Introduce the sulfur dioxide, hydrogen sulfide, and sulfur vapor generated during the regeneration process into the inlet of the first-stage Claus reactor of the sulfur recovery unit, mix it with the process gas, and carry out the Claus reaction to generate sulfur, realizing the sulfur cycle treatment and sulfur resource recovery, and reducing the emission of sulfur-containing pollutants in the tail gas of the low-temperature Claus sulfur recovery process.

[0071] Example 3

[0072] As Figure 1 described, a method for reducing sulfur-containing tail gas emissions from a low-temperature Claus sulfur recovery unit provided by an embodiment of the present invention is as follows:

[0073] (1) The tail gas from the low-temperature Claus process sulfur recovery unit enters the incinerator together with fuel gas and air for combustion. All sulfides are converted into sulfur dioxide at 600 - 800 °C, recover heat and reduce the flue gas temperature to 200 - 350 °C;

[0074] (2) The flue gas enters the oxidation catalytic reactor R1 filled with an oxidation catalytic adsorbent. At this time, V1 and V2 are opened, and V3, V4, V5, V6, V7, and V8 are closed. Under the action of the catalyst, 3000 - 5000 mg / m 3 sulfur dioxide and 3 - 6% oxygen in the flue gas are oxidized and converted into sulfates and sulfites and adsorbed in the catalyst pores;

[0075] (3) When the sulfur dioxide detector installed in the main pipe of the purified flue gas pipeline at the outlet of the oxidation catalytic reactor R1 detects that the mass concentration of sulfur dioxide reaches 50 mg / m 3 ³, V1, V2, V6 and V8 are closed, V3, V4, V7 and V5 are opened, the oxidation catalytic reactor R1 starts regeneration, and the oxidation catalytic reactor R2 starts to catalytically oxidize and adsorb sulfur dioxide. When the contents of SO2, hydrogen sulfide, and sulfur vapor detected at the outlet of the oxidation catalytic reactor R1 are zero, the supply of methane in the regeneration gas is stopped, and the oxidation catalytic reactor R1 is kept warm with nitrogen and waits for the next switch to catalytic oxidation and adsorption.

[0076] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A sulfur-containing tail gas emission reduction system for a low-temperature Claus sulfur recovery unit, characterized in that, It includes an incinerator connected to the tail gas discharge port of a low-temperature Claus sulfur recovery unit; The gas outlet end of the incinerator is connected to two parallel oxidation catalytic reactors. The outlets of the two oxidation catalytic reactors are respectively connected to the first-stage Claus reactor and the purified flue gas discharge port of the low-temperature Claus sulfur recovery unit through pipelines; A reducing gas source is also connected to the oxidation catalytic reactor; In one oxidation catalytic reactor, the incinerator tail gas is introduced in an oxidation adsorption state to adsorb sulfur dioxide in the incinerator tail gas; In the other oxidation catalytic reactor, a reducing gas is introduced in a reduction regeneration state to reduce and regenerate the adsorbed sulfur dioxide and return it to the inlet of the first-stage Claus reactor of the low-temperature Claus sulfur recovery unit.

2. The sulfur-containing tail gas emission reduction system of a low-temperature Claus sulfur recovery device according to claim 1, characterized in that The oxidation catalytic reactor is filled with an oxidation catalytic adsorbent, which is a granular catalyst formed by using aluminum hydroxide as the main material, metal oxide as the auxiliary material, organic solvent and water as the solvent and by means of compression molding.

3. The sulfur-containing tail gas emission reduction system of a low-temperature Claus sulfur recovery device according to claim 2, wherein The main material of aluminum hydroxide is obtained by subjecting aluminum hydroxide to rapid dehydration, pulverization, hydrothermal treatment, and microwave oscillation treatment. The frequency of the microwave oscillation treatment used is 300 MHz to 300 GHz, and the treatment time is 4 to 8 hours.

4. A sulfur-containing tail gas emission reduction system for a low-temperature Claus sulfur recovery device according to claim 1, characterized in that, The oxidation catalytic reactor is a vertical fixed-bed reactor. The oxidation catalytic adsorbent is filled in the middle area of the reactor, and fillers for supporting and dispersing heat are filled above and below the oxidation catalytic adsorbent bed.

5. The sulfur-containing tail gas emission reduction system of a low-temperature Claus sulfur recovery device according to claim 1, characterized in that, The two oxidation catalytic reactors use a pneumatic switching valve to achieve the switching between the oxidation adsorption state and the reduction regeneration state.

6. The sulfur-containing tail gas emission reduction system of a low-temperature Claus sulfur recovery device according to claim 1, wherein Sulfur dioxide detectors are provided at the outlets of the two oxidation catalytic reactors.

7. The sulfur-containing tail gas emission reduction system of a low-temperature Claus sulfur recovery device according to claim 1, wherein The reducing gas source includes methane and nitrogen.

8. A sulfur-containing tail gas emission reduction system for a low-temperature Claus sulfur recovery device according to claim 7, characterized in that, The composition of the reducing gas source is 80 - 90% nitrogen and 10 - 20% methane.

9. A sulfur-containing tail gas emission reduction system for a low-temperature Claus sulfur recovery device according to claim 1, characterized in that, The ratio of sulfur dioxide, hydrogen sulfide to sulfur vapor in the sulfur-containing compounds generated by reduction regeneration is 6:3:

1.

10. A method for reducing sulfur-containing tail gas emissions in a low-temperature Claus sulfur recovery unit, characterized in that, Based on the sulfur-containing tail gas emission reduction system according to any one of claims 1 to 9, it includes the following steps: (1) Introduce the sulfur-containing tail gas of the low-temperature Claus sulfur recovery unit into the incinerator, burn it with air and fuel gas, and convert it into a gas mixture of sulfur dioxide and non-sulfur compounds. Control the oxygen content of the mixed flue gas after combustion to be 2% - 5%; (2) Introduce the mixed flue gas into a reactor containing an oxidation catalytic adsorbent. Sulfur dioxide and oxygen in the flue gas undergo an oxidation catalytic reaction under the action of the catalyst to generate sulfates and sulfites and adsorb on the catalyst, and use the method of oxidation adsorption to remove the sulfur dioxide generated by the incinerator; (3) After the reactor has reacted for a certain period of time, introduce a reducing gas into the reactor containing the oxidation catalytic adsorbent, and use the reducing gas to regenerate sulfur dioxide and return it to the inlet of the first-stage Claus reactor of the low-temperature Claus sulfur recovery unit.

Images