Crude benzene hydrogenation tail gas desulfurization device and desulfurization process

Abstract

The application discloses a crude benzene hydrogenation tail gas desulfurization device and a desulfurization process thereof, which adopts a complex iron desulfurization process, and utilizes a complex iron catalyst to directly oxidize H2S in acid gas into sulfur in one step, and the selective removal rate of the complex iron catalyst to H2S can reach more than 99%, which can solve the difficulty of one-time desulfurization of the crude benzene hydrogenation tail gas, and can meet the technical requirements of hydrogenation tail gas purification and the requirements of no three-waste emission, and is in line with the national low-carbon environmental protection policy, and the crude benzene hydrogenation tail gas is realized to be recycled, hydrogen is recovered by the enterprise, hydrogen sulfide is generated into industrial sulfur, and additional benefits are created for the enterprise. The process is particularly suitable for sulfur recovery in the fields of small and medium-sized hydrogenation tail gas purification of crude benzene, coal tar, mineral oil and deep processing of gasoline and diesel oil.

Description

Technical Field

[0001] This invention relates to the field of crude benzene hydrogenation process technology, specifically to a crude benzene hydrogenation tail gas desulfurization device and its desulfurization process. Background Technology

[0002] The tail gas from the hydrogenation of crude benzene mainly refers to the acidic gas containing a high concentration of H2S generated by the front-end hydrogenation unit. The gas originates from the hydrogenation reaction of organic sulfur components (such as thioethers, mercaptans, and thiophenes) in the crude benzene feedstock. The generated hydrogen sulfide-containing gas is usually discharged in four types of tail gas forms: low-segment gas, high-segment gas, stripping tower top gas, and acidic water stripping acidic gas.

[0003] Because H2S is a highly hazardous gas with characteristics such as extreme toxicity and foul odor, direct combustion will severely corrode equipment. Furthermore, the exhaust gas contains high levels of hydrocarbons and hydrogen; burning it through a flare would waste fuel resources, and the resulting SO2 emissions would cause severe air pollution. Petrochemical companies typically use MDEA desulfurization followed by Claus sulfur recovery to remove H2S from the exhaust gas. However, this desulfurization process is complex, requires high investment, occupies a large area, and consumes a lot of energy. Moreover, the Claus sulfur recovery unit is susceptible to shutdowns due to fluctuations in the sulfur load of the upstream crude benzene feedstock, making continuous and stable operation impossible. Additionally, the sodium hydrosulfide absorption process described in patent CN218688089U cannot achieve large-scale production of sodium hydrosulfide, resulting in low efficiency. Sodium hydrosulfide is also a hazardous chemical, posing safety and environmental risks; if there is overcapacity in the sodium hydrosulfide market, the desulfurization unit must be forced to shut down. Therefore, neither the Claus process nor the sodium hydrosulfide process has solved the problem of desulfurization treatment of crude benzene hydrogenation tail gas. Thus, inventing a crude benzene hydrogenation tail gas desulfurization device and its desulfurization process would be highly beneficial. Summary of the Invention

[0004] The purpose of this invention is to provide a desulfurization device and process for crude benzene hydrogenation tail gas. It employs a complexed iron desulfurization process, utilizing a complexed iron catalyst to directly oxidize H2S in acidic gas into sulfur in one step. The selective removal rate of H2S can reach over 99%, and it produces no waste gas, wastewater, or solid waste, exhibits strong resistance to sulfur load fluctuations, operates stably, and requires minimal space. It can solve the difficulties of crude benzene hydrogenation tail gas desulfurization in one go.

[0005] To achieve the above objectives, the present invention includes a medium-pressure oil separator (11), a medium-pressure desulfurization tower (12), a flash tank (13), a low-pressure oil separator (14), a low-pressure desulfurization tower (15), a regeneration settling tank (16), a reagent tank (17), a plate and frame filter (18), a sulfur melting kettle (19), and a sulfur receiving tank (20) and a sulfur receiving tank (21).

[0006] The gas inlet (11a) of the medium-pressure oil separator (11) is connected to a mixed acidic gas of high and low separation gases from the upstream hydrogenation unit via a first pipeline (1101). The gas outlet (11b) of the medium-pressure oil separator (11) is connected to the medium-pressure desulfurization tower (12) via a second pipeline (1102). The gas outlet (12a) of the medium-pressure desulfurization tower (12) is connected to a hydrogen recovery unit outside the boundary via a third pipeline (1103). The liquid outlet (12b) of the medium-pressure desulfurization tower (12) is connected to the flash tank (13) via a fourth pipeline (1104). The gas inlet (14a) of the low-pressure oil separator (14) is connected to the upstream unit via a pipeline (1105) to a mixture of stripping tower top gas and acidic water stripping gas. The gas outlet (14b) of the low-pressure oil separator is connected to the low-pressure desulfurization tower (15) via a sixth pipeline (1106). The gas outlet (15a) of the low-pressure desulfurization tower (15) is connected to the fuel gas pipeline network outside the boundary via a seventh pipeline (1107). The liquid outlet (15b) of the low-pressure desulfurization tower (15) is connected to the flash tank (13) via an eighth pipeline (1108). 13) The liquid outlet (13a) is connected to the regeneration settling tank (16) via the ninth pipe (1109), and the gas outlet (13b) of the flash tank (13) is connected to the recycling device outside the boundary via the tenth pipe (1110); the liquid outlet (16a) of the regeneration settling tank (16) is connected to the plate and frame filter (18) via the eleventh pipe (1111), and the gas outlet (16b) of the regeneration settling tank (16) is connected to the VOCs treatment equipment via the pipe (1112); the liquid outlet (17a) of the reagent tank (17) is connected to the thirteenth pipe (1109). 1113) is connected to the regeneration settling tank (16); the liquid outlet (18a) of the plate and frame filter (18) is connected to the regeneration settling tank (16) through the fourteenth pipe (1114), and the solid outlet (18b) of the plate and frame filter (18) is connected to the sulfur melting kettle (19) through the fifteenth pipe (1115); the liquid outlet (19a) of the sulfur melting kettle (19) is connected to the sulfur receiving tank (20) through the sixteenth pipe (1116), and the gas outlet (19b) of the sulfur melting kettle (19) is connected to the VOCs treatment equipment through the seventeenth pipe (1117).

[0007] A preferred technical solution of the present invention is as follows: the medium-pressure lean liquor outlet (16c) of the regeneration settling tank (16) is connected to the medium-pressure desulfurization tower (12) through the medium-pressure lean liquor pump inlet pipe (1511), the medium-pressure lean liquor pump (151), the solution heat exchanger (161), and the eighteenth pipe (1118); the low-pressure lean liquor outlet (16d) of the regeneration settling tank (16) is connected to the medium-pressure desulfurization tower (12) through the low-pressure lean liquor pump inlet pipe (1521), the low-pressure lean liquor pump (152), and the nineteenth pipe (1118). 119) is connected to the low-pressure desulfurization tower (15), and the liquid outlet (16a) of the regeneration settling tank (16) is connected to the plate and frame filter (18) through the sulfur slurry pump inlet pipe (1531), the sulfur slurry pump (153) and the eleventh pipe (1111); the liquid outlet (18a) of the plate and frame filter (18) is connected to the regeneration settling tank (16) through the filtrate pump inlet pipe (1541), the filtrate pump (154) and the fourteenth pipe (1114).

[0008] A preferred technical solution of the present invention is as follows: it further includes a regeneration air fan (155), which is connected to the air distributor (22) at the bottom of the regeneration settling tank (16) via the twentieth outlet pipe (1120) of the regeneration air fan. It also includes a medium-pressure acid gas distributor (23) and a low-pressure acid gas distributor (24); the medium-pressure acid gas is connected to the medium-pressure acid gas distributor (23) at the bottom of the medium-pressure desulfurization tower (12) via the second pipe (1102); the low-pressure acid gas is connected to the low-pressure acid gas distributor (24) at the bottom of the low-pressure desulfurization tower (15) via the sixth pipe (1106). The liquid outlet (17a) of the reagent tank (17) is connected to the regeneration settling tank (16) via the inlet pipe (1561) of the dosing pump, the dosing pump (156) and the thirteenth pipe (1113).

[0009] Furthermore, the plate and frame filter, hopper, sulfur melting kettle, and sulfur receiving tank are arranged from high to low; the sulfur paste from the plate and frame filter falls into the low-level hopper through the height difference; the sulfur paste from the hopper falls into the low-level sulfur melting kettle through the height difference; the jacket layer of the sulfur melting kettle is heated by steam, and the liquid sulfur in the inner cylinder of the sulfur melting kettle falls into the low-level sulfur receiving tank through the height difference.

[0010] This invention also provides a desulfurization process for crude benzene hydrogenation tail gas, the specific scheme of which is as follows: 1) Complex iron desulfurization The high-pressure and low-pressure gas from the hydrotreating unit first enter the medium-pressure oil separator for oil removal (C5+ including C5) and liquid separation. Then, it enters the medium-pressure desulfurization tower at a certain liquid level for bubbling absorption reaction and is thoroughly mixed with the complexed iron catalyst pumped by the medium-pressure lean solution pump to rapidly remove H2S, reducing the H2S concentration to below 5 mg / Nm³. 3 The medium-pressure purified exhaust gas, after H2S removal, is sent to the downstream hydrogen recovery unit for hydrogen enrichment and recovery.

[0011] The acid stripping gas and hydrogenated acidic dry gas from the hydrogenation unit first enter the low-pressure oil separator for oil removal (C5+ including C5) and liquid separation. Then, they enter the low-pressure desulfurization tower at a certain liquid level for bubbling absorption reaction and rapid H2S removal through full contact with the complexed iron catalyst pumped by the low-pressure lean solution pump, reducing the H2S concentration to below 5 mg / Nm³. 3 The low-pressure purified gas, after H2S has been removed, enters the fuel gas pipeline network.

[0012] The two rich solutions absorbed by the two absorption units are then fed into a flash tank for flash evaporation. A small amount of flammable and explosive gases dissolved in the complexed iron are flashed away, and the flash vapor (H2S concentration less than 1 ppm) is sent out of the unit for recovery or to the flare network. The rich solution containing sulfur particles enters the regeneration system for solution regeneration.

[0013] 2) Centralized regeneration of complexed iron The rich solution from the flash tank enters the regeneration settling tank, where it undergoes a multi-stage contact reaction with air blown in by the regeneration air fan. This oxidizes the ferrous iron in the rich solution of the complexed iron catalyst to ferric iron. After oxidation, the solution then enters the settling zone from the regeneration zone, where sedimentation separation is achieved by utilizing the density difference between the liquid and sulfur. The catalyst with separated sulfur particles is pumped back to the corresponding desulfurization tower for recycling via medium and low-pressure lean solution pumps. The sulfur slurry at the bottom of the regeneration settling tank is pumped to the sulfur recovery section for solid-liquid separation and sulfur refining. The regenerated air consumes only a portion of the oxygen and does not generate new toxic or harmful substances. The regenerated waste air is sent to the VOCs treatment system outside the boundary.

[0014] 3) Sulfur recovery Sulfur slurry, pumped by a sulfur slurry pump, is sent to a plate and frame filter press, where it is separated into solid sulfur and absorbent. The filtrate separated from the plate and frame filter press is recycled to a regeneration settling tank, saving reagent consumption and maintaining system liquid level balance. The sulfur paste, containing 65wt% solids, separated by the plate and frame filter press, falls by gravity into a hopper below and enters a steam-melting sulfur reactor for refining. The reactor heats the solid sulfur paste with steam through a jacket until it is completely liquefied. Liquid sulfur gradually accumulates at the bottom of the reactor and is periodically released into a receiving tank below. The naturally cooled, solidified liquid sulfur forms blocks that meet industrial-grade solid sulfur standards, with a sulfur content exceeding 99wt%. The depressurized steam from the sulfur-melting reactor is combined with the regeneration waste air and then treated in an external VOCs system.

[0015] 4) Medication supplementation The chelated iron reagent is continuously replenished to the regeneration settling tank via a metering pump to maintain the system's reagent concentration balance.

[0016] Compared with the prior art, the present invention has the following advantages: 1. This invention utilizes a complexed iron desulfurization process to achieve the resource utilization of various acidic gases. Desulfurization is achieved to less than 5 mg / Nm³. 3 Medium-pressure purified gas can be used as a gas for enriching hydrogen, with a concentration of less than 5 mg / Nm³. 3 Low-pressure purified gas can be used as fuel gas, and the removed H2S sulfur can be recovered to produce industrial-grade sulfur. While meeting national environmental protection standards and technological requirements, this increases the added value of the gas and improves the economic benefits for enterprises.

[0017] 2. The technology of this invention adopts a complex iron desulfurization process which is superior to the traditional MDEA enrichment + sulfur recovery process. It has no emissions of waste, greatly simplifies the process flow, is easy to operate, and meets the current national low-carbon and environmental protection policies.

[0018] 3. The technology of this invention adopts a complex iron desulfurization process that is not affected by the pressure of the raw gas medium and the concentration of H2S. The reaction conditions are mild and it is suitable for desulfurization of crude benzene hydrogenation tail gas, as well as acid gas treatment in metallurgy, coal chemical and other industrial fields. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the crude benzene hydrogenation tail gas desulfurization device and its desulfurization process flow of the present invention. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0021] like Figure 1 As shown, the crude benzene hydrogenation tail gas desulfurization device of the present invention includes a medium-pressure oil separator (11), a medium-pressure desulfurization tower (12), a flash tank (13), a low-pressure oil separator (14), a low-pressure desulfurization tower (15), a regeneration settling tank (16), a reagent tank (17), a plate and frame filter (18), a sulfur melting kettle (19), and a sulfur receiving tank (20) and a sulfur receiving tank (21).

[0022] The gas inlet (11a) of the medium-pressure oil separator (11) is connected to a mixed acidic gas of high and low separation gases from the upstream hydrogenation unit via a first pipeline (1101). The gas outlet (11b) of the medium-pressure oil separator (11) is connected to the medium-pressure desulfurization tower (12) via a second pipeline (1102). The gas outlet (12a) of the medium-pressure desulfurization tower (12) is connected to the hydrogen recovery unit outside the boundary via a third pipeline (1103). The liquid outlet (12b) of the medium-pressure desulfurization tower (12) is connected to the flash tank (13) via a fourth pipeline (1104). The gas inlet (14a) of the low-pressure oil separator (14) is connected to the upstream unit via the fifth pipe (1105) to a mixture of stripping tower top gas and acidic water stripping gas. The gas outlet (14b) of the low-pressure oil separator is connected to the low-pressure desulfurization tower (15) via the sixth pipe (1106). The gas outlet (15a) of the low-pressure desulfurization tower (15) is connected to the fuel gas pipeline outside the boundary via the seventh pipe (1107). The liquid outlet (15b) of the low-pressure desulfurization tower (15) is connected to the flash tank (13) via the eighth pipe (1108). 13) The liquid outlet (13a) is connected to the regeneration settling tank (16) via the ninth pipe (1109), and the gas outlet (13b) of the flash tank (13) is connected to the recycling device outside the boundary via the tenth pipe (1110); the liquid outlet (16a) of the regeneration settling tank (16) is connected to the plate and frame filter (18) via the eleventh pipe (1111), and the gas outlet (16b) of the regeneration settling tank (16) is connected to the VOCs treatment equipment via the twelfth pipe (1112); the liquid outlet (17a) of the reagent tank (17) is connected to the thirteenth pipe (1113) is connected to the regeneration settling tank (16); the liquid outlet (18a) of the plate and frame filter (18) is connected to the regeneration settling tank (16) through the fourteenth pipe (1114), and the solid outlet (18b) of the plate and frame filter (18) is connected to the sulfur melting kettle (19) through the fifteenth pipe (1115); the liquid outlet (19a) of the sulfur melting kettle (19) is connected to the sulfur receiving tank (20) through the sixteenth pipe (1116), and the gas outlet (19b) of the sulfur melting kettle (19) is connected to the VOCs treatment equipment through the seventeenth pipe (1117).

[0023] The medium-pressure lean liquor outlet (16c) of the regeneration settling tank (16) is connected to the medium-pressure desulfurization tower (12) through the medium-pressure lean liquor pump inlet pipe (1511), the medium-pressure lean liquor pump (151), the solution heat exchanger (161), and the eighteenth pipe (1118). The low-pressure lean liquor outlet (16d) of the regeneration settling tank (16) is connected to the low-pressure desulfurization tower (12) through the low-pressure lean liquor pump inlet pipe (1521), the low-pressure lean liquor pump (152), and the nineteenth pipe (1119). The desulfurization tower (15) is connected, and the liquid outlet (16a) of the regeneration settling tank (16) is connected to the plate and frame filter (18) through the sulfur slurry pump inlet pipe (1531), the sulfur slurry pump (153) and the eleventh pipe (1111); the liquid outlet (18a) of the plate and frame filter (18) is connected to the regeneration settling tank (16) through the filtrate pump inlet pipe (1541), the filtrate pump (154) and the fourteenth pipe (1114).

[0024] The crude benzene hydrogenation tail gas desulfurization device of the present invention also includes a regeneration air fan (155), which is connected to the air distributor (22) at the bottom of the regeneration settling tank (16) via the twentieth outlet pipe (1120). It also includes a medium-pressure acid gas distributor (23) and a low-pressure acid gas distributor (24); the medium-pressure acid gas is connected to the medium-pressure acid gas distributor (23) at the bottom of the medium-pressure desulfurization tower (12) via a second pipe (1102); the low-pressure acid gas is connected to the low-pressure acid gas distributor (24) at the bottom of the low-pressure desulfurization tower (15) via a sixth pipe (1106). The liquid outlet (17a) of the reagent tank (17) is connected to the regeneration settling tank (16) via the dosing pump inlet pipe (1561), the dosing pump (156), and the thirteenth pipe (1113). The plate and frame filter, hopper, sulfur melting kettle, and sulfur receiving tank are arranged from high to low; the sulfur paste from the plate and frame filter falls into the low-level hopper through the height difference; the sulfur paste from the hopper falls into the low-level sulfur melting kettle through the height difference; the jacket layer of the sulfur melting kettle is heated by steam, and the liquid sulfur in the inner cylinder of the sulfur melting kettle falls into the low-level sulfur receiving tank through the height difference.

[0025] The present invention provides a crude benzene hydrogenation tail gas desulfurization process that specifically includes the following steps: 1) Complex iron desulfurization The high-pressure and low-pressure gases from the hydrogenation unit first enter the medium-pressure oil separator 11 equipped with filter element 25 via the first pipeline 1101 for oil removal (C5+ including C5) and liquid separation. Then, they enter the medium-pressure desulfurization tower 12 at a certain liquid level via the second pipeline 1102 for bubbling absorption reaction. They are then fully mixed with the complexed iron catalyst delivered by the medium-pressure lean liquid pump 151 to rapidly remove H2S, reducing the H2S concentration to below 5 mg / Nm³. 3 The medium-pressure purified gas, after H2S removal, is sent to the downstream hydrogen recovery unit via the third pipeline 1103 for hydrogen enrichment and recovery.

[0026] The acid water stripping gas and hydrogenated acidic dry gas from the hydrogenation unit first enter the low-pressure oil separator 14 equipped with filter element 26 via the fifth pipe 1105 for oil removal (C5+ including C5) and liquid separation. Then, they enter the low-pressure desulfurization tower 15 at a certain liquid level via the sixth pipe 1106 for bubbling absorption reaction and rapid H2S removal by fully contacting the complexed iron catalyst delivered by the low-pressure lean liquid pump 152, so that the H2S concentration is below 5 mg / Nm³. 3 The low-pressure purified gas, after H2S removal, is sent to the fuel gas pipeline network via the seventh pipeline 1107.

[0027] The rich solutions from the bottom of the medium-pressure desulfurization tower 12 and the low-pressure desulfurization tower 15 enter the flash tank 13 via the fourth pipe 1104 and the eighth pipe 1108, respectively, for flash evaporation. This flash evaporation removes a small amount of flammable and explosive gases dissolved in the complexed iron. The flash vapor (H2S concentration less than 1 ppm) is sent out of the system for recovery or to the flare network via the tenth pipe 1110. The rich solution containing sulfur particles at the bottom of the flash tank 13 enters the regeneration system via the ninth pipe 1109 for solution regeneration.

[0028] 2) Centralized regeneration of complexed iron The rich liquor from flash tank 13 enters regeneration settling tank 16, where it undergoes a multi-stage contact reaction with air blown in by regeneration air fan 155. This oxidizes the ferrous iron in the rich liquor containing the complexed iron catalyst to ferric iron. After oxidation, the solution enters the settling zone from the regeneration zone, where sedimentation separation is achieved by utilizing the density difference between the liquid and sulfur. The catalyst from which sulfur particles have been separated is returned to the corresponding desulfurization towers 12 and 15 for recycling via medium-pressure lean liquor pump 151 and low-pressure lean liquor pump 152. The sulfur slurry at the bottom of regeneration settling tank 16 is sent to the sulfur recovery section via sulfur slurry pump 153 for solid-liquid separation and sulfur refining. The regenerated air consumes only a portion of the oxygen and does not generate new toxic or harmful substances. The regenerated waste air is sent to the VOCs treatment system outside the boundary via the twelfth pipe 1112.

[0029] 3) Sulfur recovery The sulfur slurry pumped by sulfur slurry pump 153 is sent to plate and frame filter press 18 via eleventh pipe 1111, where it is separated into solid sulfur and absorbent. The filtrate separated from plate and frame filter press 18 is returned to regeneration settling tank 16 via fourteenth pipe 1114, saving reagent consumption and maintaining system liquid level balance. The sulfur paste containing 65wt% solids separated by plate and frame filter press 18 falls into hopper 18b directly below by gravity and then enters sulfur melting kettle 19 via fifteenth pipe 1115 for steam sulfur melting and refining. Sulfur melting kettle 19 heats the solid sulfur paste with steam through jacket 19A until the sulfur paste is completely liquefied. The liquid sulfur gradually accumulates in the lower layer of sulfur melting kettle 19 and is periodically released into sulfur receiving tank 20 directly below via sixteenth pipe 1116. The liquid sulfur naturally cools and forms block sulfur that meets the requirements of industrial qualified solid sulfur with a sulfur content of over 99wt%. The steam released from the depressurized sulfur melting kettle 19 is sent via the seventeenth pipeline 1117 to merge with the twelfth pipeline 1112 and then enters the VOCs system outside the boundary area for treatment.

[0030] 4) Medication supplementation The chelated iron reagent is continuously replenished to the regeneration settling tank 16 via the dosing pump 156 to maintain the balance of the reagent concentration in the system.

Claims

1. A crude benzene hydrogenation tail gas desulfurization device, comprising a medium-pressure oil separator (11), a medium-pressure desulfurization tower (12), a flash tank (13), a low-pressure oil separator (14), a low-pressure desulfurization tower (15), a regeneration settling tank (16), a reagent tank (17), a plate and frame filter (18), a sulfur melting kettle (19), and a sulfur receiving tank (20), characterized in that: The inlet (11a) of the medium-pressure oil separator (11) is connected to a mixed gas via a first pipe (1101). The mixed gas is a mixture of high-splitting gas and low-splitting gas produced by the upstream hydrogenation unit. The gas outlet (11b) of the medium-pressure oil separator (11) is connected to the medium-pressure desulfurization tower (12) via a second pipe (1102). The gas outlet (12a) of the medium-pressure desulfurization tower (12) is connected to the hydrogen recovery unit outside the boundary via a third pipe (1103). The liquid outlet (12b) of the medium-pressure desulfurization tower (12) is connected to the flash tank (13) via a fourth pipe (1104). The inlet (14a) of the low-pressure oil separator (14) is connected to the fifth pipe (1105). The mixed gas is formed by mixing the stripping tower top gas produced by the upstream hydrogenation unit with the stripping acid gas. The gas outlet (14b) of the low-pressure oil separator is connected to the low-pressure desulfurization tower (15) through the sixth pipeline (1106). The gas outlet (15a) of the low-pressure desulfurization tower (15) is connected to the fuel gas pipeline network outside the boundary through the seventh pipeline (1107). The liquid outlet (15b) of the low-pressure desulfurization tower (15) is connected to the flash tank (13) through the eighth pipeline (1108). The liquid outlet (13a) of the flash tank (13) is connected to the regeneration settling tank (16) through the ninth pipeline (1109). The gas outlet (13b) of the flash tank (13) is connected to the recovery device outside the boundary through the tenth pipeline (1110). The liquid outlet (16a) of the regeneration settling tank (16) is connected to the eleventh pipeline (1109). 111) Connected to the plate and frame filter (18), the gas outlet (16b) of the regeneration settling tank (16) is connected to the VOCs treatment equipment through the twelfth pipe (1112); the liquid outlet (17a) of the reagent tank (17) is connected to the regeneration settling tank (16) through the thirteenth pipe (1113); the liquid outlet (18a) of the plate and frame filter (18) is connected to the regeneration settling tank (16) through the fourteenth pipe (1114), the solid outlet (18b) of the plate and frame filter (18) is connected to the sulfur melting kettle (19) through the fifteenth pipe (1115); the liquid outlet (19a) of the sulfur melting kettle (19) is connected to the sulfur receiving tank (20) through the sixteenth pipe (1116), and the gas outlet (19b) of the sulfur melting kettle (19) is connected to the VOCs treatment equipment through the seventeenth pipe (1117).

2. The crude benzene hydrogenation tail gas desulfurization device according to claim 1, characterized in that: The medium-pressure lean liquor outlet (16c) of the regeneration settling tank (16) is connected to the medium-pressure desulfurization tower (12) through the medium-pressure lean liquor pump inlet pipe (1511), the medium-pressure lean liquor pump (151), the solution heat exchanger (161), and the eighteenth pipe (1118). The low-pressure lean liquor outlet (16d) of the regeneration settling tank (16) is connected to the low-pressure desulfurization tower (12) through the low-pressure lean liquor pump inlet pipe (1521), the low-pressure lean liquor pump (152), and the nineteenth pipe (1119). The sulfur slurry outlet (16a) of the regeneration settling tank (16) is connected to the plate and frame filter (18) through the sulfur slurry pump inlet pipe 31 (1531), the sulfur slurry pump (153) and the eleventh pipe (1111); the liquid outlet (18a) of the plate and frame filter (18) is connected to the regeneration settling tank (16) through the filtrate pump inlet pipe 41 (1541), the filtrate pump (154) and the fourteenth pipe (1114).

3. The crude benzene hydrogenation tail gas desulfurization device according to claim 1, characterized in that: It also includes a regenerated air fan (155), which is connected to the air distributor (22) at the bottom of the regenerated settling tank (16) via the twentieth pipe (1120) at the outlet of the regenerated air fan.

4. The crude benzene hydrogenation tail gas desulfurization device according to claim 1, characterized in that: It also includes a medium-pressure acid gas distributor (23) and a low-pressure acid gas distributor (24); the medium-pressure acid gas is connected to the medium-pressure acid gas distributor (23) at the bottom of the medium-pressure desulfurization tower (12) through a second pipe (1102); the low-pressure acid gas is connected to the low-pressure acid gas distributor (24) at the bottom of the low-pressure desulfurization tower (15) through a sixth pipe (1106).

5. The crude benzene hydrogenation tail gas desulfurization device according to claim 1, characterized in that: The liquid outlet (17a) of the reagent tank (17) is connected to the regeneration settling tank (16) through the sixty-first pipe (1561) of the dosing pump inlet, the dosing pump (156) and the thirteenth pipe (1113).

6. A crude benzene hydrogenation tail gas desulfurization process, comprising the following steps: 1) Complex iron desulfurization The high-pressure and low-pressure gas from the hydrotreating unit first enter the medium-pressure oil separator for oil removal and liquid separation, and then enter the medium-pressure desulfurization tower for bubbling absorption reaction. There, it is thoroughly mixed with the complexed iron catalyst pumped from the medium-pressure lean solution pump for rapid H2S removal, reducing the H2S concentration to below 5 mg / Nm³. 3 The medium-pressure purified exhaust gas, after H2S removal, is sent to the downstream hydrogen recovery unit for hydrogen enrichment and recovery. Acid stripping gas and hydrogenated acid dry gas from the hydrotreating unit first enter the low-pressure oil separator for oil removal and liquid separation, and then enter the low-pressure desulfurization tower for bubbling absorption reaction. They then undergo a rapid reaction with the complexed iron catalyst pumped from the low-pressure lean solution to remove H2S, bringing the H2S concentration below 5 mg / Nm³. 3 The low-pressure purified gas, after H2S has been removed, then enters the fuel gas pipeline network. The two rich liquids absorbed by the two absorption units above enter the flash tank together for flash evaporation, in which a small amount of flammable and explosive gas dissolved in the complexed iron catalyst is flashed. The flash vapor is sent out of the device for recovery or sent to the flare pipeline network. The rich liquid containing sulfur particles enters the regeneration system for solution regeneration. 2) Centralized regeneration of complexed iron The rich solution from the flash tank enters the regeneration settling tank, where it undergoes a multi-stage contact reaction with the air blown in by the regeneration air fan. This oxidizes the ferrous iron in the rich solution of the complexed iron catalyst to ferric iron. After oxidation, the solution then enters the settling zone from the regeneration zone, where sedimentation separation is achieved by utilizing the density difference between the liquid and sulfur. The catalyst with separated sulfur particles is pumped back to the corresponding desulfurization tower for recycling via medium and low pressure lean solution pumps. The sulfur slurry at the bottom of the regeneration settling tank is pumped to the sulfur recovery section for solid-liquid separation and sulfur refining. The regenerated air consumes only a portion of the oxygen and does not generate any new toxic or harmful substances. The regenerated waste air is sent to a VOCs treatment system outside the boundary. 3) Sulfur recovery The sulfur slurry pumped by the sulfur slurry pump is sent to a plate and frame filter press, where it is separated into solid sulfur and absorbent. The filtrate separated from the plate and frame filter press is recycled to a regeneration settling tank. The sulfur paste containing 65wt% solids separated from the plate and frame filter press falls into the hopper directly below by gravity and enters the sulfur melting kettle for steam sulfur refining. The sulfur melting kettle heats the solid sulfur paste with steam through a jacket until the sulfur paste is completely liquefied. The liquid sulfur gradually accumulates in the lower layer of the sulfur melting kettle. Sulfur is periodically released from the bottom of the sulfur melting kettle into the sulfur receiving tank directly below. The liquid sulfur cools naturally in the sulfur receiving tank and forms into block solid sulfur that meets industrial quality standards, with a sulfur content of over 99wt%. The steam released from the sulfur melting kettle is sent to be combined with the regeneration waste air and then sent to the VOCs system outside the boundary for treatment.

7. The crude benzene hydrogenation tail gas desulfurization process according to claim 6, characterized in that: It is implemented using the following apparatus, which includes a medium-pressure oil separator (11), a medium-pressure desulfurization tower (12), a flash tank (13), a low-pressure oil separator (14), a low-pressure desulfurization tower (15), a regeneration settling tank (16), a reagent tank (17), a plate and frame filter (18), a sulfur melting kettle (19), and a sulfur receiving tank (20). The characteristic feature is that the air inlet (11a) of the medium-pressure oil separator (11) is connected to a first pipe (1101). A mixed gas is introduced, which is a mixture of high-splitting gas and low-splitting gas produced by the upstream hydrogenation unit. The gas outlet (11b) of the medium-pressure oil separator (11) is connected to the medium-pressure desulfurization tower (12) through a second pipeline (1102). The gas outlet (12a) of the medium-pressure desulfurization tower (12) is connected to the hydrogen recovery unit outside the boundary through a third pipeline (1103). The liquid outlet (12b) of the medium-pressure desulfurization tower (12) is connected to the flash tank (13) through a fourth pipeline (1104). The air inlet (14a) of the low-pressure oil separator (14) is connected to the flash tank (13) through a fifth pipeline (1105). The mixed gas is formed by mixing the stripping tower top gas produced by the upstream hydrogenation unit with the stripping acid gas. The gas outlet (14b) of the low-pressure oil separator is connected to the low-pressure desulfurization tower (15) through the sixth pipeline (1106). The gas outlet (15a) of the low-pressure desulfurization tower (15) is connected to the fuel gas pipeline network outside the boundary through the seventh pipeline (1107). The liquid outlet (15b) of the low-pressure desulfurization tower (15) is connected to the flash tank (13) through the eighth pipeline (1108). The liquid outlet (13a) of the flash tank (13) is connected to the regeneration settling tank (16) through the ninth pipeline (1109). The gas outlet (13b) of the flash tank (13) is connected to the recovery device outside the boundary through the tenth pipeline (1110). The liquid outlet (16a) of the regeneration settling tank (16) is connected to the eleventh pipeline (1109). 111) Connected to the plate and frame filter (18), the gas outlet (16b) of the regeneration settling tank (16) is connected to the VOCs treatment equipment through the twelfth pipe (1112); the liquid outlet (17a) of the reagent tank (17) is connected to the regeneration settling tank (16) through the thirteenth pipe (1113); the liquid outlet (18a) of the plate and frame filter (18) is connected to the regeneration settling tank (16) through the fourteenth pipe (1114), the solid outlet (18b) of the plate and frame filter (18) is connected to the sulfur melting kettle (19) through the fifteenth pipe (1115); the liquid outlet (19a) of the sulfur melting kettle (19) is connected to the sulfur receiving tank (20) through the sixteenth pipe (1116), and the gas outlet (19b) of the sulfur melting kettle (19) is connected to the VOCs treatment equipment through the seventeenth pipe (1117).

8. The crude benzene hydrogenation tail gas desulfurization process according to claim 7, characterized in that: The medium-pressure lean liquor outlet (16c) of the regeneration settling tank (16) is connected to the medium-pressure desulfurization tower (12) through the medium-pressure lean liquor pump inlet pipe (1511), the medium-pressure lean liquor pump (151), the solution heat exchanger (161), and the eighteenth pipe (1118). The low-pressure lean liquor outlet (16d) of the regeneration settling tank (16) is connected to the low-pressure desulfurization tower (12) through the low-pressure lean liquor pump inlet pipe (1521), the low-pressure lean liquor pump (152), and the nineteenth pipe (1119). The sulfur tower (15) is connected, and the liquid outlet (16a) of the regeneration settling tank (16) is connected to the plate and frame filter (18) through the sulfur slurry pump inlet 31 pipe (1531), the sulfur slurry pump (153) and the 11th pipe (1111); the liquid outlet (18a) of the plate and frame filter (18) is connected to the regeneration settling tank (16) through the filtrate pump inlet 41 pipe (1541), the filtrate pump (154) and the 14th pipe (1114).

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