Low-concentration acid gas treatment process and treatment device

Abstract

The invention belongs to the technical field of sulfur recovery, and particularly relates to a treatment process and a treatment device for ultralow-concentration acid gas, which are applicable to treatment of acid gas with H2S less than 1% in industries such as coal chemical industry and the like. According to the treatment process of the ultralow-concentration acid gas, the ultralow-concentration acid gas and Claus hydrogenation tail gas are mixed, then introduced into the steam generator for cooling and further introduced into the quench tower for treatment, so that on one hand, the temperature of the hydrogenation tail gas can be reduced, and on the other hand, the effect of injecting ammonia into quenched water can be achieved; while sulfur resources are fully recovered, dual treatment of H2S and NH3 in the ultralow-concentration acid gas is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of sulfur recovery, and specifically relates to a processing technology and a processing device for ultra-low concentration acid gas, which is suitable for the processing of acid gas with H2S less than 1% in industries such as coal chemical industry. Background Art

[0002] In recent years, with the sharp rise in international oil prices, the cost of chemical processes using oil as raw materials has increased significantly, and people have turned their attention to coal chemical technology, which has enabled the traditional coal chemical technology to be redeveloped and many new coal chemical technologies have emerged. my country has also vigorously developed coal chemical industry and has successively developed new energy processes such as methanol, synthetic ammonia, coal-to-oil and olefins using coal as raw materials to alleviate the pressure on oil and gas resources. However, the development of coal chemical technology has inevitably brought about a series of environmental problems.

[0003] In coal chemical plants, the concentration of hydrogen sulfide in the stripping gas of each separator condensate is generally less than 1%. This acid gas has the characteristics of low H2S concentration, high CO2, and NH3, and cannot be directly introduced into the sulfur plant for treatment. At present, all coal chemical companies use the method of directly discharging this gas into the atmosphere after flaring, which seriously pollutes the environment. In addition, some small refineries and purification plants also emit low-concentration hydrogen sulfide waste gas as a by-product, which also poses serious environmental problems. For the recovery of this type of ultra-low concentration acid gas, it is obviously inappropriate and unrealistic to build a new large-scale sulfur recovery unit. Therefore, the treatment of ultra-low concentration acid gas has become an urgent problem to be solved in the chemical industry.

[0004] For example, Chinese patent CN105293446A provides a low-sulfur emission sulfur recovery process for low-concentration acid gas, which treats low-concentration acid gas with an H2S content of less than 5% through a selective oxidation reactor and two adsorption desulfurization towers that can be connected in series to achieve the purpose of desulfurization. However, the adsorbent in the adsorption tower of this process needs to be regenerated frequently, and the adsorbent is easily worn out, resulting in complex operation and high replacement cost.

[0005] For example, Chinese patent CN109019524A discloses a sulfur recovery process for medium and low concentration acid gas, the main equipment includes a combustion furnace, a two-stage Claus reactor, a selective hydrogenation reduction reactor, a selective oxidation reactor, a circulating absorption unit and a liquid sulfur tank connected in series along the acid gas flow direction; the circulating absorption unit includes an absorption tower, the circulating absorption liquid is an alkali liquid and / or a calcium liquid, and the main water source is the condensed water of the steam contained in the process gas. However, this process is not only complicated, but also has high construction and operation costs, serious equipment corrosion, and waste alkali liquid is generated, which is easy to form new pollution.

[0006] For example, Chinese patent CN113731145A provides a method and device for reducing the temperature of a quench tower during sulfur recovery. The method is to cool the quench water of the quench tower in two stages: circulating water cools the quench water in one stage, and frozen ethylene glycol solution cools the quench water in two stages. The quench water after two stages of cooling is in direct contact with the hydrogenation reduction tail gas for cooling. The hydrogenation reduction tail gas is converted into acid gas after cooling and sent to the first stage preheater. However, this process requires the use of ethylene glycol to cool the quench water and liquid ammonia to cool the ethylene glycol solution, and multiple heat exchangers, storage tanks and tower equipment need to be added. There are also problems of complex process flow and high construction and operation costs.

[0007] In view of this, how to solve the problem of ultra-low concentration acid gas treatment has positive significance for the healthy and green development of the coal chemical industry. Summary of the invention

[0008] Therefore, the technical problem to be solved by the present invention is to provide a process for treating ultra-low concentration acid gas, which can solve the problem of the difficulty in treating ultra-low concentration acid gas at present, fully recover sulfur resources, and effectively utilize ammonia therein. The process is simple to operate and has strong adaptability. It is suitable for treating acid gas with H2S concentration lower than 1%, and can be widely used in the treatment of ultra-low concentration acid gas in coal chemical industry, petrochemical industry and other industries.

[0009] The second technical problem solved by the present invention is to provide a device for treating ultra-low concentration acid gas.

[0010] In order to solve the above technical problems, a low-concentration acid gas treatment process described in the present invention comprises the following steps:

[0011] (1) mixing the low-concentration acid gas to be treated with Claus hydrogenation tail gas to obtain a mixed gas;

[0012] (2) subjecting the mixed gas to steam cooling;

[0013] (3) condensing the mixed gas after the temperature is reduced;

[0014] (4) absorbing the condensed quenched tail gas with amine liquid;

[0015] (5) The purified tail gas generated after amine liquid absorption is incinerated and then discharged.

[0016] Specifically, the treatment process of the low-concentration acid gas is as follows:

[0017] The H2S content in the Claus hydrogenation tail gas is less than 2(v)%;

[0018] The H2S content in the low-concentration acid gas is less than 1(v)%.

[0019] Specifically, in the process for treating low-concentration acid gas, in the step (2), the steam cooling step includes the step of cooling the mixed gas by introducing it into a steam generator;

[0020] Preferably, the mixed gas is cooled to 140-150° C. by the steam generator, and liquid sulfur is separated from the hydrogenation tail gas.

[0021] Specifically, in the process for treating low-concentration acid gas, in the step (3), the condensation step includes the step of passing the mixed gas into a quenching tower;

[0022] Preferably, the pH value of the quench tower is controlled to be 7-9; and the outlet gas temperature of the quench tower is controlled to be 25-40°C.

[0023] Specifically, in the process for treating low-concentration acid gas, in step (4), the amine liquid absorption step includes the step of allowing the quenched tail gas to enter an absorption tower filled with a desulfurization solvent to absorb H2S.

[0024] Specifically, the low-concentration acid gas treatment process, in the step (3), further comprises the step of regenerating the rich amine liquid produced at the bottom of the absorption tower in a regeneration tower;

[0025] Preferably, in the regeneration step, the temperature at the top of the regeneration tower is controlled at 100-115° C., the temperature at the bottom of the tower is controlled at 115-120° C., and the pressure at the top of the tower is controlled at 0.06-0.10 MPa.

[0026] Specifically, in the process for treating low-concentration acid gas, in step (4), in step (1), further comprises the step of separating liquid from the low-concentration acid gas by using a mixed gas buffer tank.

[0027] Specifically, the process for treating low-concentration acid gas further comprises the step of preparing Claus hydrogenation tail gas;

[0028] Preferably, the Claus hydrogenation tail gas is Claus hydrogenation tail gas obtained by a sulfur recovery process;

[0029] Preferably, the step of preparing the Claus hydrogenated tail gas comprises the steps of using the acid gas of the sulfur process as raw material, recovering sulfur through thermal reaction and catalytic reaction, and performing hydrogenation treatment on the generated Claus tail gas.

[0030] The present invention also discloses a low-concentration acid gas processing device, comprising a mixed gas buffer tank, a steam generator, a quenching tower, an absorption tower and an incinerator connected by pipelines; wherein:

[0031] The mixed gas buffer tank is used to mix the Claus hydrogenation tail gas with the ultra-low concentration acid gas;

[0032] The steam generator is used to cool the mixed gas by steam;

[0033] The quenching tower is used to condense the mixed gas after the temperature is reduced;

[0034] The absorption tower is used to absorb the quenched tail gas with amine liquid;

[0035] The incinerator is used to incinerate the purified gas generated after the amine liquid absorbs.

[0036] The present invention also discloses a low-concentration acid gas processing device, which includes a sulfur recovery device and a mixed gas buffer tank arranged before the steam generator of the sulfur recovery device, and is used to mix the Claus hydrogenation tail gas with the ultra-low concentration acid gas;

[0037] Preferably, the mixed gas buffer tank is arranged between the hydrogenation reactor and the steam generator of the sulfur recovery unit.

[0038] The ultra-low concentration acid gas treatment process of the present invention adopts a method of mixing the ultra-low concentration acid gas with Claus hydrogenation tail gas, introducing the mixture into a steam generator for cooling, and further introducing the mixture into a quenching tower for treatment. On the one hand, the temperature of the hydrogenation tail gas can be reduced, and on the other hand, ammonia can be injected into the quenching water, fully recovering sulfur resources while achieving dual treatment of H2S and NH3 in the ultra-low concentration acid gas. The ultra-low concentration acid gas treatment method of the present invention can solve the current problem of the difficulty in treating ultra-low concentration acid gas, fully recover sulfur resources, and effectively utilize ammonia therein. The process is simple to operate and has strong adaptability. It is suitable for treating acidic gases with H2S concentrations below 1%, and can be widely used in the treatment of ultra-low concentration acid gas in coal chemical industry, petrochemical industry and other industries.

[0039] The method for treating ultra-low concentration acid gas of the present invention makes full use of the existing conditions of the sulfur device, introduces the ultra-low concentration acid gas into the steam generator and further introduces it into the quenching tower, is simple to operate, has strong adaptability, and has low construction investment; the method can fully recover the sulfur resources in the ultra-low concentration acid gas, and the ammonia therein can also be effectively utilized; and the entire process does not generate waste liquid, is safe and environmentally friendly, and does not generate secondary pollution. The method for treating ultra-low concentration acid gas of the present invention can solve the problem of difficulty in treating acid gas with a concentration of less than 1%, avoid polluting the environment after emission of flare incineration, and meet the requirements of various environmental protection laws and regulations.

[0040] The ultra-low concentration acid gas treatment device provided by the present invention comprises a thermal reaction unit, a catalytic reaction unit and a tail gas purification unit. The acid gas of the sulfur process first undergoes thermal reaction and catalytic reaction to recover sulfur, and then enters the tail gas purification unit. In the tail gas purification unit, the hydrogenated tail gas after Claus tail gas hydrogenation is mixed with the ultra-low concentration acid gas and then enters the steam generator for cooling, and further enters the quenching tower for cooling and condensation. The quenched tail gas is absorbed by the amine liquid absorption tower, and the purified tail gas enters the incinerator for incineration and then is discharged through the chimney to meet the standards. The device described in the present invention can be applied based on the improvement of the sulfur recovery device, and can solve the current problem of the difficulty in treating ultra-low concentration acid gas. The ultra-low concentration acid gas is introduced into the quenching tower to reduce the temperature of the hydrogenated tail gas on the one hand, and on the other hand, it can play the role of injecting ammonia into the quenching water, fully recovering sulfur resources while realizing the dual treatment of H2S and NH3 in the ultra-low concentration acid gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0042] Figure 1 It is a structural schematic diagram of the ultra-low concentration acid gas processing device of the present invention;

[0043] Figure 2 This is a schematic diagram of the structure of the processing device used in the comparative example 1 of the present invention;

[0044] The reference numerals in the figure are represented as follows: 1-acid gas, 2-air, 3-sulfur making furnace, 4-primary condenser, 5-primary heater, 6-primary converter, 7-secondary condenser, 8-secondary heater, 9-secondary converter, 10-third stage condenser, 11-tail gas heater, 12-hydrogenation reactor, 13-mixed gas buffer tank, 14-liquid sulfur pool, 15-steam generator, 16-quenching tower, 17-absorption tower, 18-lean and rich liquid heat exchanger, 19-regeneration tower, 20-incinerator, 21-chimney. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention.

[0046] As attached Figure 1 The device shown in the following embodiment of the present invention is an improvement on the basis of the existing sulfur recovery device.

[0047] As attached Figure 1 The device shown in the present invention provides an ultra-low concentration acid gas processing device, which includes a thermal reaction unit, a catalytic reaction unit and a tail gas purification unit.

[0048] like Figure 1 As shown in the schematic diagram of the device structure, the thermal reaction unit includes a sulfur-making furnace 3 and a primary condenser 4 connected in sequence.

[0049] In the thermal reaction unit, the H2S-containing acid gas 1 and the air 2 are partially burned in the sulfur-making furnace 3 and converted into SO2. At high temperature, H2S and SO2 undergo a Claus reaction to generate sulfur-making furnace tail gas, in which the elemental sulfur is cooled to 160-170°C by the primary condenser 4 and then enters the liquid sulfur pool 14 provided in the device to obtain liquid sulfur. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0050] In the thermal reaction unit, the acid gas containing H2S is mixed with air and burned in the sulfur-making furnace 3, and one-third of the H2S is burned and converted into SO2, and a Claus reaction occurs at high temperature as follows:

[0051] 2H2S+3O2→2SO2+2H2O;

[0052] SO2+2H2S→2H2O+3S;

[0053] The reaction forms a process gas containing elemental sulfur, H2S, SO2, COS and CS2, wherein the elemental sulfur is condensed by the primary condenser 4 and enters the liquid sulfur pool 14, and the process gas enters the catalytic reaction unit.

[0054] The combustion temperature of the sulfur-making furnace 3 is controlled at 900-1400°C, preferably 1100-1350°C.

[0055] The volume ratio of H2S and SO2 in the sulfur-making furnace tail gas is 2:1.

[0056] like Figure 1 As shown in the schematic diagram of the device structure, the catalytic reaction unit includes a primary heater 5, a primary converter 6, a secondary condenser 7, a secondary heater 8, a secondary converter 9, and a tertiary condenser 10 connected in sequence.

[0057] In the catalytic reaction unit, the sulfur-making furnace tail gas is first heated to 230-250° C. by the primary heater 5, and then enters the primary converter 6 to react under the action of the catalyst to generate the primary converter tail gas, which enters the secondary condenser 7 for condensation and separation, and the elemental sulfur therein enters the liquid sulfur pool 14 to obtain liquid sulfur. The separated primary converter tail gas is heated to 210-240° C. by the secondary heater 8, enters the secondary converter 9 for reaction, and is converted by Claus catalysis under the action of the catalyst to generate Claus tail gas. The Claus tail gas enters the tertiary condenser 10 for condensation, and the liquid sulfur generated after condensation enters the liquid sulfur pool 14 in the device. The separated Claus tail gas enters the tail gas purification unit.

[0058] In the catalytic reaction unit, the process gas generated by the thermal reaction unit enters the primary converter 6 and the secondary converter 9, and the following reactions occur under the action of the catalyst:

[0059] SO2+2H2S→2H2O+3S;

[0060] COS+H2O→H2S+CO2;

[0061] CS2+2H2O→2H2S+CO2;

[0062] After two-stage Claus catalytic conversion, elemental sulfur is condensed through the condenser and enters the liquid sulfur pool 14. The Claus tail gas after the reaction contains trace elemental sulfur, H2S, SO2 and sulfides such as COS and CS2, and enters the tail gas purification unit.

[0063] A primary heater 5 is provided before the primary converter 6 to control the inlet temperature of the primary converter 6 to 230-250°C.

[0064] A secondary heater 8 is provided before the secondary converter 9 to control the inlet temperature of the secondary converter 9 to 210-240°C.

[0065] The recommended grading scheme of the primary converter 6 is: 1 / 3 of the sulfur recovery catalyst with oxygen leakage function is filled in the upper part, and 2 / 3 of the titanium oxide-based sulfur recovery catalyst with high organic sulfur hydrolysis activity is filled in the lower part.

[0066] The secondary converter 9 is completely filled with an alumina-based sulfur-producing catalyst.

[0067] The oxygen leakage protection type sulfur recovery catalyst is preferably the LS-971 catalyst developed by the Research Institute of Sinopec Qilu Branch. It is used to protect or reduce the sulfation damage of the catalyst below caused by the oxygen leakage in the process gas, thereby extending the service life of the catalyst. In addition, the process of removing oxygen leakage will generate a large amount of reaction heat, thereby increasing the reaction temperature, which is conducive to the hydrolysis reaction of organic sulfur.

[0068] The titanium oxide-based sulfur recovery catalyst is preferably the LS-981G catalyst developed by the Research Institute of Sinopec Qilu Branch. The LS-981G catalyst has higher catalytic activity for the hydrolysis reaction of organic sulfides and the Claus reaction of H2S and SO2, almost reaching thermodynamic equilibrium, and is insensitive to "O2 poisoning". The catalyst has a slow hydrolysis deactivation rate and can maintain a relatively stable organic sulfur hydrolysis activity throughout the entire service life.

[0069] The alumina-based sulfur-making catalyst is preferably the LS-02 catalyst developed by the Research Institute of Sinopec Qilu Branch. The catalyst has high Claus activity, strong resistance to thermal aging and hydrothermal aging, uniform particles, low abrasion, and high crushing strength, thereby ensuring the long-term operation of the catalyst; the catalyst has more macropores and a bimodal pore structure, so that the sulfur generated by the reaction quickly leaves the catalyst pores, further improving the Claus activity and organic sulfur hydrolysis activity of the catalyst.

[0070] Figure 1 As shown in the schematic diagram of the device structure, the exhaust gas purification unit includes an exhaust gas heater 11, a hydrogenation reactor 12, a mixed gas buffer tank 13, a steam generator 15, a quenching tower 16, an absorption tower 17, a lean and rich liquid heat exchanger 18, a regeneration tower 19, an incinerator 20 and a chimney 21 which are connected in sequence.

[0071] In the tail gas purification unit, Claus tail gas is reheated to 250-280°C by tail gas heater 11 and then enters hydrogenation reactor 12. Under the action of hydrogenation catalyst in hydrogenation reactor 12, sulfur-containing compounds are hydrogenated and converted into H2S. The hydrogenated tail gas with H2S content less than 2(v)% enters mixed gas buffer tank 13 and is mixed with ultra-low concentration acid gas 22 with H2S content less than 1(v)%. After the mixed gas is cooled by steam generator 15, it enters quenching tower 16 to cool to 25-38°C, and then enters absorption tower 17, wherein the H2S is countercurrently contacted and absorbed by the lean amine liquid from the bottom of the regeneration tower 19, and the rich amine liquid at the bottom of the absorption tower 17 is heat exchanged in the lean-rich liquid heat exchanger 18, and then enters the regeneration tower 19 for regeneration, the temperature at the top of the regeneration tower is controlled at 100-115°C, the temperature at the bottom of the tower is controlled at 115-120°C, the pressure at the top of the tower is 0.06-0.10Mpa, the regenerated acid gas at the top of the regeneration tower 19 is returned to the sulfur-making furnace, and the purified tail gas at the top of the absorption tower 17 is entered into the incinerator 20 for incineration, and the flue gas after incineration is discharged through the chimney 21 in compliance with the emission standards.

[0072] In the tail gas purification unit, the Claus tail gas generated by the catalytic reaction unit enters the hydrogenation reactor. Under the action of the hydrogenation catalyst, the elemental sulfur, SO2 and the like carried in the tail gas are all hydrogenated and converted into H2S, and COS and CS2 are hydrolyzed and converted into H2S. The reaction is as follows:

[0073] S x +xH2→xH2S;

[0074] SO2+3H2→H2S+2H2O.

[0075] The hydrogenation tail gas containing H2S is mixed with the ultra-low concentration acid gas in the mixed gas buffer tank 13. The mixed gas is cooled by the steam generator 15 and then enters the quench tower 16. After being cooled by the quench tower 16, it enters the amine liquid absorption tower 17 filled with a formulated high-efficiency desulfurization solvent. The H2S is absorbed by the amine liquid. The rich amine liquid at the bottom of the absorption tower 17 enters the regeneration tower 19 for regeneration. The purified tail gas at the top of the absorption tower enters the incinerator 20 for incineration. The flue gas after incineration is discharged through the chimney 21 in compliance with the emission standards.

[0076] A tail gas heater 11 is provided before the hydrogenation reactor 12 to control the inlet temperature of the hydrogenation reactor 12 to be 250-300°C, preferably 250-280°C.

[0077] The hydrogenation reactor 12 is filled with a multifunctional high-activity tail gas hydrogenation catalyst.

[0078] The multifunctional high-activity tail gas hydrogenation catalyst is preferably the LSH-03G catalyst developed by the Research Institute of Sinopec Qilu Branch. The catalyst has excellent low-temperature hydrogenation and hydrolysis activity and CO shift activity.

[0079] The mixed gas is a mixed gas of ultra-low concentration acid gas and hydrogenation tail gas.

[0080] The mixed gas buffer tank 13 can be arranged at any position between the hydrogenation reactor and the steam generator.

[0081] The mixed gas buffer tank 13 can separate liquids such as methanol from the ultra-low concentration acid gas.

[0082] After the mixed gas is cooled to 160-170° C. by the steam generator 15 , liquid sulfur is separated from the mixed gas.

[0083] The pH value of the quench tower 16 is controlled at 7-9.

[0084] The ultra-low concentration acid gas may contain ammonia or may not contain ammonia.

[0085] If the ultra-low concentration acid gas contains ammonia, the ammonia therein can be used as ammonia supplement for quenching water to avoid a decrease in the pH value of the quenching water.

[0086] The outlet gas temperature of the quench tower 16 is 25-40°C, preferably 25-38°C.

[0087] The rich amine liquid at the bottom of the absorption tower 17 enters the regeneration tower for regeneration, and the regenerated acid gas returns to the sulfur-making furnace for recycling and reuse as the acid gas source of the sulfur-making unit, thereby realizing a closed-loop circulation of sulfur resources.

[0088] The top temperature of the regeneration tower 19 is controlled at 100-115° C., the bottom temperature is controlled at 115-120° C., and the top pressure is 0.06-0.10 MPa.

[0089] The acid gas regenerated at the top of the regeneration tower 19 is returned to the sulfur-making furnace for recycling.

[0090] In the following embodiments of the present invention, in the processing device, the first-stage heater, the second-stage heater and the tail gas heater are not limited to heating with medium-pressure steam, but are also applicable to heating methods such as gas-to-gas heat exchange, high-temperature blending, electric heating, and a heating furnace.

[0091] Example 1

[0092] The ultra-low concentration acid gas treatment process described in this embodiment adopts the following Figure 1 The processing device shown includes the following steps of thermal reaction, catalytic reaction and tail gas hydrogenation.

[0093] (1) Thermal reaction unit

[0094] Acid gas 1 containing 65 (v / v)% H2S and air 2 are partially burned in a sulfur-making furnace 3 to be converted into SO2. At 1150°C, H2S and SO2 undergo Claus reaction to generate sulfur-making furnace tail gas, in which elemental sulfur is cooled to 160°C by a primary condenser 4 and then enters a liquid sulfur pool 14 to obtain liquid sulfur. The separated sulfur-making furnace tail gas enters a catalytic reaction unit.

[0095] (2) Catalytic reaction unit

[0096] The sulfur-making furnace tail gas is first heated to 240°C by the primary heater 5, and then enters the primary converter 6 (temperature 310°C, 1 / 3 LS-971 catalyst is loaded on the upper part of the reactor, and 2 / 3 LS-981G catalyst is loaded on the lower part), and the primary converter tail gas is generated under the action of the catalyst, and enters the secondary condenser 7 for condensation and separation. The elemental sulfur therein enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 150°C. The separated primary converter tail gas is heated to 215°C by the secondary heater 8, and enters the secondary converter 9 (temperature 250°C, the reactor is fully loaded with LS-02 catalyst), and Claus tail gas is generated under the action of the catalyst. The Claus tail gas enters the tertiary condenser 10 for condensation. The liquid sulfur generated after condensation enters the liquid sulfur pool 14. The outlet temperature of the tertiary condenser 10 is 145°C. The separated Claus tail gas enters the tail gas purification unit.

[0097] (3) Tail gas hydrogenation unit

[0098] The Claus tail gas is reheated to 250°C by the tail gas heater 11 and then enters the hydrogenation reactor 12. Under the action of the hydrogenation catalyst in the hydrogenation reactor 12, the sulfur-containing compounds are hydrogenated and converted into H2S. The hydrogenated tail gas with an H2S content of 1.9 (v)% and the ultra-low concentration acid gas 22 with an H2S content of 0.9 (v)% are mixed in the mixed gas buffer tank 13. The mixed gas is cooled to 150°C by the steam generator 15, and then enters the quench tower 16 to be quenched to 35°C, and then enters the absorption Tower 17, where H2S is countercurrently contacted and absorbed by the lean amine liquid from the bottom of the regeneration tower 19. The rich amine liquid at the bottom of the absorption tower 17 is heat exchanged in the lean-rich liquid heat exchanger 18 and then enters the regeneration tower 19 for regeneration. The temperature at the top of the tower is 100°C, the temperature at the bottom of the tower is controlled at 115°C, and the pressure at the top of the tower is 0.08Mpa. The regenerated acid gas at the top of the regeneration tower returns to the sulfur making furnace. The purified tail gas at the top of the absorption tower 17 enters the incinerator 20 for incineration. The flue gas after incineration is discharged through the chimney 21 to meet the emission standards (SO2 emission <50mg / m 3 ).

[0099] Example 2

[0100] The ultra-low concentration acid gas treatment process described in this embodiment adopts the following Figure 1 The processing device shown includes the following steps of thermal reaction, catalytic reaction and tail gas hydrogenation.

[0101] (1) Thermal reaction unit

[0102] Acid gas 1 containing 70 (v / v)% H2S and air 2 are partially burned in a sulfur-making furnace 3 and converted into SO2. H2S and SO2 undergo Claus reaction at 1200°C to generate sulfur-making furnace tail gas, in which elemental sulfur is cooled to 162°C by a primary condenser 4 and then enters a liquid sulfur pool 14 to obtain liquid sulfur. The separated sulfur-making furnace tail gas enters a catalytic reaction unit.

[0103] (2) Catalytic reaction unit

[0104] The sulfur-making furnace tail gas is first heated to 230°C by the primary heater 5, and then enters the primary converter 6 (temperature 313°C, 1 / 3 LS-971 catalyst is loaded on the upper part of the reactor, and 2 / 3 LS-981G catalyst is loaded on the lower part), and the primary converter tail gas is generated under the action of the catalyst, and enters the secondary condenser 7 for condensation and separation. The elemental sulfur therein enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 152°C. The separated primary converter tail gas is heated to 210°C by the secondary heater 8, and enters the secondary converter 9 (temperature 245°C, the reactor is fully loaded with LS-02 catalyst), and Claus tail gas is generated under the action of the catalyst. The Claus tail gas enters the tertiary condenser 10 for condensation. The liquid sulfur generated after condensation enters the liquid sulfur pool 14. The outlet temperature of the tertiary condenser 10 is 145°C. The separated Claus tail gas enters the tail gas purification unit.

[0105] (3) Tail gas hydrogenation unit

[0106] Claus tail gas is reheated to 250°C by tail gas heater 11 and then enters hydrogenation reactor 12. Under the action of hydrogenation catalyst in hydrogenation reactor 12, sulfur compounds are hydrogenated and converted into H2S. The hydrogenated tail gas with H2S content of 1.2 (v)% is mixed with ultra-low concentration acid gas 22 with H2S content of 0.8 (v)% in mixed gas buffer tank 13. The mixed gas is cooled to 148°C by steam generator 15, and then enters quenching tower 16 to be rapidly cooled to 32°C, and then enters absorption Tower 17, where H2S is countercurrently contacted and absorbed by the lean amine liquid from the bottom of the regeneration tower 19. The rich amine liquid at the bottom of the absorption tower 17 is heat exchanged in the lean-rich liquid heat exchanger 18 and then enters the regeneration tower 19 for regeneration. The temperature at the top of the tower is 110°C, the temperature at the bottom of the tower is controlled at 117°C, and the pressure at the top of the tower is 0.08Mpa. The regenerated acid gas at the top of the regeneration tower returns to the sulfur making furnace. The purified tail gas at the top of the absorption tower 17 enters the incinerator 20 for incineration. The flue gas after incineration is discharged through the chimney 21 to meet the emission standards (SO2 emission <50mg / m 3 ).

[0107] Example 3

[0108] The ultra-low concentration acid gas treatment process described in this embodiment adopts the following Figure 1 The processing device shown includes the following steps of thermal reaction, catalytic reaction and tail gas hydrogenation.

[0109] (1) Thermal reaction unit

[0110] Acid gas 1 containing 65 (v / v)% H2S and air 2 are partially burned in a sulfur-making furnace 3 and converted into SO2. At 1200°C, H2S and SO2 undergo Claus reaction to generate sulfur-making furnace tail gas, in which elemental sulfur is cooled to 162°C by a primary condenser 4 and then enters a liquid sulfur pool 14 to obtain liquid sulfur. The separated sulfur-making furnace tail gas enters a catalytic reaction unit.

[0111] (2) Catalytic reaction unit

[0112] The sulfur-making furnace tail gas is first heated to 240°C by the primary heater 5, and then enters the primary converter 6 (temperature 310°C, 1 / 3 LS-971 catalyst is loaded on the upper part of the reactor, and 2 / 3 LS-981G catalyst is loaded on the lower part), and the primary converter tail gas is generated under the action of the catalyst, and enters the secondary condenser 7 for condensation and separation. The elemental sulfur therein enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 150°C. The separated primary converter tail gas is heated to 215°C by the secondary heater 8, and enters the secondary converter 9 (temperature 250°C, the reactor is fully loaded with LS-02 catalyst), and Claus tail gas is generated under the action of the catalyst. The Claus tail gas enters the tertiary condenser 10 for condensation. The liquid sulfur generated after condensation enters the liquid sulfur pool 14. The outlet temperature of the tertiary condenser 10 is 145°C. The separated Claus tail gas enters the tail gas purification unit.

[0113] (3) Tail gas hydrogenation unit

[0114] The Claus tail gas is reheated to 255°C by the tail gas heater 11 and then enters the hydrogenation reactor 12. Under the action of the hydrogenation catalyst in the hydrogenation reactor 12, the sulfur-containing compounds are hydrogenated and converted into H2S. The hydrogenated tail gas with an H2S content of 0.9 (v)% is mixed with the ultra-low concentration acid gas 22 with an H2S content of 0.5 (v)% in the mixed gas buffer tank 13. The mixed gas is cooled to 145°C by the steam generator 15, and then enters the quench tower 16 to be quenched to 30°C, and then enters the absorption Tower 17, where H2S is countercurrently contacted and absorbed by the lean amine liquid from the bottom of the regeneration tower 19. The rich amine liquid at the bottom of the absorption tower 17 is heat exchanged in the lean-rich liquid heat exchanger 18 and then enters the regeneration tower 19 for regeneration. The temperature at the top of the tower is 108°C, the temperature at the bottom of the tower is controlled at 116°C, and the pressure at the top of the tower is 0.07Mpa. The regenerated acid gas at the top of the regeneration tower returns to the sulfur making furnace. The purified tail gas at the top of the absorption tower 17 enters the incinerator 20 for incineration. The flue gas after incineration is discharged through the chimney 21 to meet the emission standards (SO2 emission <50mg / m 3 ).

[0115] Example 4

[0116] The ultra-low concentration acid gas treatment process described in this embodiment adopts the following Figure 1 The processing device shown includes the following steps of thermal reaction, catalytic reaction and tail gas hydrogenation.

[0117] (1) Thermal reaction unit

[0118] Acid gas 1 containing 65 (v / v)% H2S and air 2 are partially burned in a sulfur-making furnace 3 and converted into SO2. At 1200°C, H2S and SO2 undergo Claus reaction to generate sulfur-making furnace tail gas, in which elemental sulfur is cooled to 160°C by a primary condenser 4 and then enters a liquid sulfur pool 14 to obtain liquid sulfur. The separated sulfur-making furnace tail gas enters a catalytic reaction unit.

[0119] (2) Catalytic reaction unit

[0120] The sulfur-making furnace tail gas is first heated to 245°C by the primary heater 5, and then enters the primary converter 6 (temperature 320°C, 1 / 3 LS-971 catalyst is loaded on the upper part of the reactor, and 2 / 3 LS-981G catalyst is loaded on the lower part), and the primary converter tail gas is generated under the action of the catalyst, and enters the secondary condenser 7 for condensation and separation. The elemental sulfur therein enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 155°C. The separated primary converter tail gas is heated to 210°C by the secondary heater 8, and enters the secondary converter 9 (temperature 245°C, the reactor is fully loaded with LS-02 catalyst), and Claus tail gas is generated under the action of the catalyst. The Claus tail gas enters the tertiary condenser 10 for condensation. The liquid sulfur generated after condensation enters the liquid sulfur pool 14. The outlet temperature of the tertiary condenser 10 is 143°C. The separated Claus tail gas enters the tail gas purification unit.

[0121] (3) Tail gas hydrogenation unit

[0122] The Claus tail gas is reheated to 260°C by the tail gas heater 11 and then enters the hydrogenation reactor 12. Under the action of the hydrogenation catalyst in the hydrogenation reactor 12, the sulfur-containing compounds are hydrogenated and converted into H2S. The hydrogenated tail gas with an H2S content of 0.7 (v)% and the ultra-low concentration acid gas 22 with an H2S content of 0.9 (v)% are mixed in the mixed gas buffer tank 13. The mixed gas is cooled to 143°C by the steam generator 15, and then enters the quench tower 16 to be quenched to 28°C, and then enters the absorption Tower 17, where H2S is countercurrently contacted and absorbed by the lean amine liquid from the bottom of the regeneration tower 19. The rich amine liquid at the bottom of the absorption tower 17 is heat exchanged in the lean-rich liquid heat exchanger 18 and then enters the regeneration tower 19 for regeneration. The temperature at the top of the tower is 109°C, the temperature at the bottom of the tower is controlled at 118°C, and the pressure at the top of the tower is 0.07Mpa. The regenerated acid gas at the top of the regeneration tower returns to the sulfur making furnace. The purified tail gas at the top of the absorption tower 17 enters the incinerator 20 for incineration. The flue gas after incineration is discharged through the chimney 21 to meet the emission standards (SO2 emission <50mg / m 3 ).

[0123] Example 5

[0124] The ultra-low concentration acid gas treatment process described in this embodiment adopts the following Figure 1 The processing device shown includes the following steps of thermal reaction, catalytic reaction and tail gas hydrogenation.

[0125] (1) Thermal reaction unit

[0126] Acid gas 1 containing 75 (v / v)% H2S and air 2 are partially burned in a sulfur-making furnace 3 to be converted into SO2. At 1250°C, H2S and SO2 undergo Claus reaction to generate sulfur-making furnace tail gas, in which elemental sulfur is cooled to 165°C by a primary condenser 4 and then enters a liquid sulfur pool 14 to obtain liquid sulfur. The separated sulfur-making furnace tail gas enters a catalytic reaction unit.

[0127] (2) Catalytic reaction unit

[0128] The sulfur-making furnace tail gas is first heated to 245°C by the primary heater 5, and then enters the primary converter 6 (temperature 325°C, 1 / 3 LS-971 catalyst is loaded on the upper part of the reactor, and 2 / 3 LS-981G catalyst is loaded on the lower part), and the primary converter tail gas is generated under the action of the catalyst, and enters the secondary condenser 7 for condensation and separation. The elemental sulfur therein enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 153°C. The separated primary converter tail gas is heated to 215°C by the secondary heater 8, and enters the secondary converter 9 (temperature 245°C, the reactor is fully loaded with LS-02 catalyst), and Claus tail gas is generated under the action of the catalyst. The Claus tail gas enters the tertiary condenser 10 for condensation. The liquid sulfur generated after condensation enters the liquid sulfur pool 14. The outlet temperature of the tertiary condenser 10 is 144°C. The separated Claus tail gas enters the tail gas purification unit.

[0129] (3) Tail gas hydrogenation unit

[0130] The Claus tail gas is reheated to 280°C by the tail gas heater 11 and then enters the hydrogenation reactor 12. Under the action of the hydrogenation catalyst in the hydrogenation reactor 12, the sulfur-containing compounds are hydrogenated and converted into H2S. The hydrogenated tail gas with an H2S content of 1.9 (v)% and the ultra-low concentration acid gas 22 with an H2S content of 0.5 (v)% are mixed in the mixed gas buffer tank 13. The mixed gas is cooled to 142°C by the steam generator 15, and then enters the quench tower 16 to be quenched to 26°C, and then enters the absorption Tower 17, where H2S is countercurrently contacted and absorbed by the lean amine liquid from the bottom of the regeneration tower 19. The rich amine liquid at the bottom of the absorption tower 17 is heat exchanged in the lean-rich liquid heat exchanger 18 and then enters the regeneration tower 19 for regeneration. The temperature at the top of the tower is 115°C, the temperature at the bottom of the tower is controlled at 120°C, and the pressure at the top of the tower is 0.09Mpa. The regenerated acid gas at the top of the regeneration tower returns to the sulfur making furnace. The purified tail gas at the top of the absorption tower 17 enters the incinerator 20 for incineration. The flue gas after incineration is discharged through the chimney 21 to meet the emission standards (SO2 emission <50mg / m 3 ).

[0131] Comparative Example 1:

[0132] The ultra-low concentration acid gas treatment process described in this comparative example adopts the following Figure 2 The ultra-low concentration acid gas to be treated is the same as that in Example 1.

[0133] The difference between the treatment method described in this comparative example and the treatment method in Example 1 is that the ultra-low concentration acid gas is directly introduced into the furnace head of the sulfur-making furnace for treatment, and the other processes are the same as in Example 1.

[0134] This treatment method requires preheating of the air, which greatly increases the energy consumption of the device. In severe cases, it will cause the sulfur-making furnace to shut down. In addition, the CO2 in the ultra-low concentration acid gas will generate a large amount of CO in the sulfur-making furnace, causing the CO emissions of the sulfur recovery device to be unqualified.

[0135] Comparative Example 2

[0136] The method for treating the ultra-low concentration acid gas in this comparative example is to discharge the ultra-low concentration acid gas (the components are the same as those in Example 5) directly into the atmosphere after being burned by a flare, and the SO2 emission concentration is 5000 mg / m 3 , seriously polluting the environment.

[0137] The embodiments of the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A process for treating low-concentration acid gas, characterized in that: The steps include: (1) mixing the low-concentration acid gas to be treated with Claus hydrogenation tail gas to obtain a mixed gas; (2) subjecting the mixed gas to steam cooling; (3) condensing the mixed gas after the temperature is reduced; (4) absorbing the condensed quenched tail gas with amine liquid; (5) The purified tail gas generated after amine liquid absorption is incinerated and then discharged.

2. The process for treating low-concentration acid gas according to claim 1, characterized in that: The H2S content in the Claus hydrogenation tail gas is less than 2(v)%; The H2S content in the low-concentration acid gas is less than 1(v)%.

3. The process for treating low-concentration acid gas according to claim 1 or 2, characterized in that: In the step (2), the steam cooling step includes the step of cooling the mixed gas by entering a steam generator; Preferably, the mixed gas is cooled to 140-150° C. by the steam generator, and liquid sulfur is separated from the hydrogenation tail gas.

4. The process for treating low-concentration acid gas according to any one of claims 1 to 3, characterized in that: In the step (3), the condensation step includes the step of passing the mixed gas into a quenching tower; Preferably, the pH value of the quench tower is controlled to be 7-9; and the outlet gas temperature of the quench tower is controlled to be 25-40°C.

5. The process for treating low-concentration acid gas according to any one of claims 1 to 4, characterized in that: In the step (4), the amine liquid absorption step includes the step of allowing the quenched tail gas to enter an absorption tower filled with a desulfurization solvent to absorb H2S.

6. The process for treating low-concentration acid gas according to claim 5, characterized in that: The step (3) further includes the step of regenerating the rich amine solution produced at the bottom of the absorption tower in a regeneration tower; Preferably, in the regeneration step, the temperature at the top of the regeneration tower is controlled at 100-115° C., the temperature at the bottom of the tower is controlled at 115-120° C., and the pressure at the top of the tower is controlled at 0.06-0.10 MPa.

7. The process for treating low-concentration acid gas according to any one of claims 1 to 6, characterized in that: In the step (4), in the step (1), the step of separating the liquid in the low-concentration acid gas by using a mixed gas buffer tank is also included.

8. The process for treating low-concentration acid gas according to any one of claims 1 to 7, characterized in that: The method further comprises the step of preparing Claus hydrogenation tail gas; Preferably, the Claus hydrogenation tail gas is Claus hydrogenation tail gas obtained by a sulfur recovery process; Preferably, the step of preparing the Claus hydrogenated tail gas comprises the steps of using the acid gas of the sulfur process as raw material, recovering sulfur through thermal reaction and catalytic reaction, and performing hydrogenation treatment on the generated Claus tail gas.

9. A low-concentration acid gas treatment device, characterized in that: It includes a mixed gas buffer tank, a steam generator, a quench tower, an absorption tower and an incinerator connected by pipelines; among which, The mixed gas buffer tank is used to mix the Claus hydrogenation tail gas with the ultra-low concentration acid gas; The steam generator is used to cool the mixed gas by steam; The quenching tower is used to condense the mixed gas after the temperature is reduced; The absorption tower is used to absorb the quenched tail gas with amine liquid; The incinerator is used to incinerate the purified gas generated after the amine liquid absorbs.

10. A low-concentration acid gas treatment device, characterized in that: The processing device includes a sulfur recovery device and a mixed gas buffer tank arranged before the steam generator of the sulfur recovery device, which is used to mix the Claus hydrogenation tail gas with the ultra-low concentration acid gas; Preferably, the mixed gas buffer tank is arranged between the hydrogenation reactor and the steam generator of the sulfur recovery unit.

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