A method and device for treating low concentration acid gas

Abstract

The present application belongs to the technical field of sulfur recovery, and particularly relates to a treatment method and a treatment device for ultra-low-concentration acid gas, which are suitable for the treatment of acid gas with H2S less than 1% in the coal chemical industry and the like. The treatment method for ultra-low-concentration acid gas adopts a mode of mixing the ultra-low-concentration acid gas with Claus hydrogenation tail gas and then introducing the mixture into a quench tower for treatment, which can reduce the temperature of the hydrogenation tail gas on the one hand and can play a role of ammonia injection for quench water on the other hand, so that sulfur resources can be fully recovered and H2S and NH3 in the ultra-low-concentration acid gas can be treated at the same time.

Description

Technical Field

[0001] This invention belongs to the field of sulfur recovery technology, specifically relating to a method and device for treating ultra-low concentration acidic gas, applicable to the treatment of acidic gas with H2S content less than 1% in industries such as coal chemical industry. Background Technology

[0002] In recent years, with the sharp rise in international oil prices, the cost of petroleum-based chemical processes has increased significantly. This has led to a renewed focus on coal chemical technology, resulting in the resurgence of traditional coal chemical technologies and the emergence of numerous new ones. my country has also vigorously developed its coal chemical industry, successively developing new energy processes for producing methanol, synthetic ammonia, coal-to-oil, and olefins from coal to alleviate 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 hydrogen sulfide concentration in the stripping gas from the condensate of various separators is generally less than 1%. This acidic gas is characterized by low H2S concentration, high CO2 content, and NH3 content, making it unsuitable for direct treatment in sulfur processing units. Currently, coal chemical enterprises treat this gas by directly flaring it into the atmosphere, causing severe environmental pollution. Furthermore, some small oil refineries and purification plants also emit low-concentration hydrogen sulfide waste gas as a byproduct, posing similar serious environmental problems. Building new large-scale sulfur recovery units is clearly unsuitable and impractical for recovering such ultra-low concentration acidic gases. Therefore, the treatment of ultra-low concentration acidic gases 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 acidic gas. This process treats low-concentration acidic gas with an H2S content of less than 5% through a selective oxidation reactor and two adsorption desulfurization towers that can be connected in parallel to achieve desulfurization. However, this process requires frequent regeneration of the adsorbent in the adsorption towers, and the adsorbent is easily depleted, resulting in complex operation and high replacement costs.

[0005] For example, Chinese patent CN109019524A discloses a sulfur recovery process for low-to-medium concentration acidic gas. The main equipment, along the flow direction of the acidic gas, 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. The circulating absorption unit includes an absorption tower, and the circulating absorbent is an alkaline solution and / or a calcium-containing solution, with the main water source being the condensate from the steam contained in the process gas. However, this process is not only complex but also has high construction and operating costs, causes severe equipment corrosion, and generates waste alkaline solution, which can easily lead to new pollution.

[0006] For example, Chinese patent CN113731145A provides a method and apparatus for reducing the temperature of a quench tower during sulfur recovery. This method involves two-stage cooling of the quench water in the quench tower: first-stage cooling with circulating water, and second-stage cooling with a frozen ethylene glycol solution. The cooled quench water is then directly contacted with the hydrogenation reduction tail gas for further cooling. After cooling, the hydrogenation reduction tail gas is converted into acidic gas 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, necessitating the addition of multiple heat exchangers, storage tanks, and tower equipment. This also presents the problems of complex process flow and high construction and operating costs.

[0007] Therefore, solving the problem of ultra-low concentration acid gas treatment is of 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 method for treating ultra-low concentration acid gas. This method can solve the current problem of difficulty in treating ultra-low concentration acid gas, fully recover sulfur resources, and effectively utilize ammonia. This process is simple to operate, highly adaptable, and suitable for treating acid gas with H2S concentration below 1%. It can be widely used in the treatment of ultra-low concentration acid gas in industries such as coal chemical and petrochemical.

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

[0010] To solve the above-mentioned technical problems, the present invention provides a method for treating low-concentration acidic gas, characterized by comprising the following steps:

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

[0012] (2) The mixture is condensed;

[0013] (3) The condensed exhaust gas is absorbed by amine solution;

[0014] (4) The purified exhaust gas generated after absorbing the amine liquid is incinerated and then discharged.

[0015] Specifically, the method for treating the low-concentration acidic gas is as follows:

[0016] The H2S content in the Claus hydrogenation tail gas is less than 2 (v)%.

[0017] The H2S content in the low-concentration acidic gas is less than 1 (v)%.

[0018] Specifically, in the method for treating the low-concentration acidic gas, step (2) includes the step of introducing the mixed gas into a quench tower.

[0019] 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℃.

[0020] Specifically, in the method for treating low-concentration acidic gas, step (3) includes the step of absorbing the amine solution into an absorption tower containing desulfurization solvent for H2S absorption.

[0021] Specifically, in the method for treating low-concentration acidic gas, step (3) further includes a step of regenerating the rich amine liquid generated at the bottom of the absorption tower in a regeneration tower.

[0022] Preferably, in the regeneration step, the temperature at the top of the regeneration tower is controlled at 100-115℃, the temperature at the bottom of the tower is controlled at 115-120℃, and the pressure at the top of the tower is controlled at 0.06-0.10 MPa.

[0023] Specifically, in the method for treating low-concentration acidic gas, step (3) of step (1) further includes the step of separating the liquid in the low-concentration acidic gas using a mixed gas buffer tank.

[0024] Specifically, the method for treating the low-concentration acidic gas further includes the step of preparing Claus hydrogenation tail gas;

[0025] Preferably, the Claus hydrogenation tail gas is Claus hydrogenation tail gas obtained from the sulfur recovery process.

[0026] Specifically, the method for treating the low-concentration acid gas includes the following steps for preparing the Claus hydrogenation tail gas: using acid gas from the sulfur process as raw material, recovering sulfur through thermal and catalytic reactions; and treating the generated Claus tail gas with hydrogen.

[0027] This invention also discloses a device for treating low-concentration acidic gas, comprising a mixed gas buffer tank, a quench tower, an absorption tower, and an incinerator connected by pipelines; wherein,

[0028] The mixed gas buffer tank is used to mix the Claus hydrogenation tail gas with the ultra-low concentration acid gas;

[0029] The quench tower is used to condense the mixed gas.

[0030] The absorption tower is used to absorb the quenched tail gas with amine solution;

[0031] The incinerator is used to burn the purified gas generated after the amine solution is absorbed.

[0032] The present invention also discloses a treatment device for low-concentration acid gas, the treatment device including a sulfur recovery device and a mixed gas buffer tank disposed before the quench tower of the sulfur recovery device, for mixing the Claus hydrogenation tail gas with the ultra-low concentration acid gas.

[0033] Preferably, the mixed gas buffer tank is located between the steam generator and the quench tower of the sulfur recovery unit.

[0034] The method for treating ultra-low concentration acidic gas described in this invention involves mixing the ultra-low concentration acidic gas with Claus hydrogenation tail gas and then introducing the mixture into a quench tower for treatment. This method lowers the temperature of the hydrogenation tail gas and simultaneously injects ammonia into the quench water, achieving both efficient sulfur recovery and dual treatment of H2S and NH3 in the ultra-low concentration acidic gas. This method solves the current problem of difficult treatment of ultra-low concentration acidic gas, fully recovering sulfur resources while effectively utilizing the ammonia. The process is simple to operate, highly adaptable, and suitable for treating acidic gases with H2S concentrations below 1%. It can be widely applied in the treatment of ultra-low concentration acidic gas in industries such as coal chemical and petrochemical.

[0035] The method for treating ultra-low concentration acidic gas described in this invention fully utilizes the existing conditions of the sulfur treatment plant, introducing the ultra-low concentration acidic gas into a quench tower. It is simple to operate, highly adaptable, and requires low construction investment. While fully recovering sulfur resources from the ultra-low concentration acidic gas, the method also effectively utilizes the ammonia present. Furthermore, the entire process generates no waste liquid, is safe and environmentally friendly, and does not produce secondary pollution. This method for treating ultra-low concentration acidic gas solves the problem of treating acidic gas with a concentration of less than 1%, avoids environmental pollution after flare incineration, and meets various environmental regulations.

[0036] The present invention provides an apparatus for treating ultra-low concentration acidic gas, comprising a thermal reaction unit, a catalytic reaction unit, and a tail gas purification unit. Acidic gas from the sulfur process first undergoes thermal and catalytic reactions to recover sulfur, then enters the tail gas purification unit. In the tail gas purification unit, the hydrogenated tail gas from Claus tail gas is mixed with the ultra-low concentration acidic gas and then enters a quench tower for condensation and cooling. The quenched tail gas is absorbed by an amine absorption tower, and the purified tail gas is incinerated in an incinerator before being discharged through a chimney to meet emission standards. The apparatus described in this invention is based on an improved sulfur recovery device and can solve the current problem of difficult treatment of ultra-low concentration acidic gas. Introducing the ultra-low concentration acidic gas into the quench tower can, on the one hand, reduce the temperature of the hydrogenated tail gas, and on the other hand, serve to inject ammonia into the quench water, thus fully recovering sulfur resources while achieving dual treatment of H2S and NH3 in the ultra-low concentration acidic gas. Attached Figure Description

[0037] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0038] Figure 1 This is a schematic diagram of the structure of the ultra-low concentration acid gas treatment device of the present invention;

[0039] Figure 2 This is a schematic diagram of the processing device structure used in Comparative Example 1 of the present invention;

[0040] The reference numerals in the diagram are as follows: 1-Acid gas, 2-Air, 3-Sulfur production furnace, 4-First-stage condenser, 5-First-stage heater, 6-First-stage converter, 7-Second-stage condenser, 8-Second-stage heater, 9-Second-stage converter, 10-Third-stage condenser, 11-Tail gas heater, 12-Hydrogenation reactor, 13-Steam generator, 14-Liquid sulfur pool, 15-Mixed gas buffer tank, 16-Quick cooler, 17-Absorption tower, 18-Lean and rich liquid heat exchanger, 19-Regeneration tower, 20-Incinerator, 21-Chimney. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0042] As attached Figure 1 The apparatus shown in the following embodiment of the present invention uses an improved method for treating ultra-low concentration acidic gas based on an existing sulfur recovery device.

[0043] As attached Figure 1 The apparatus shown is a treatment device for ultra-low concentration acidic gas provided by the present invention, comprising a thermal reaction unit, a catalytic reaction unit, and an exhaust gas purification unit.

[0044] like Figure 1 The schematic diagram of the device shown indicates that the thermal reaction unit includes a sulfur-producing furnace 3 and a primary condenser 4 connected in sequence.

[0045] In the thermal reaction unit, acidic gas 1 containing H2S and air 2 are partially combusted in the sulfur-making furnace 3 to convert into SO2. At high temperature, H2S and SO2 undergo a Claus reaction to generate sulfur-making furnace tail gas. The elemental sulfur in the gas is cooled to 160-170°C by the primary condenser 4 and then enters the liquid sulfur pool 14 set in the device to obtain liquid sulfur. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0046] In the thermal reaction unit, acidic gas containing H2S is mixed with air and burned in the sulfur-making furnace 3. One-third of the H2S is burned into SO2, and the Claus reaction occurs at high temperature as follows:

[0047] 2H₂S + 3O₂ → 2SO₂ + 2H₂O;

[0048] SO2 + 2H2S → 2H2O + 3S;

[0049] The reaction produces a process gas containing elemental sulfur, H2S, SO2, COS, and CS2. The elemental sulfur is condensed by the primary condenser 4 and enters the liquid sulfur pool 14. The process gas then enters the catalytic reaction unit.

[0050] The combustion temperature of the sulfur-making furnace 3 is controlled at 900-1400℃, preferably 1100-1350℃.

[0051] The volume ratio of H2S to SO2 in the tail gas from the sulfur production furnace is 2:1.

[0052] like Figure 1 The schematic diagram of the device structure shown indicates that the catalytic reaction unit includes a first-stage heater 5, a first-stage converter 6, a second-stage condenser 7, a second-stage heater 8, a second-stage converter 9, and a third-stage condenser 10 connected in sequence.

[0053] In the catalytic reaction unit, the sulfur-producing furnace tail gas is first heated to 230-250°C by the primary heater 5, and then enters the primary converter 6. Under the action of the catalyst, it reacts to generate primary converter tail gas, which enters the secondary condenser 7 for condensation and separation. The elemental sulfur in the tail gas 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 and enters the secondary converter 9 for reaction. Under the action of the catalyst, it undergoes Claus catalytic conversion to generate Claus tail gas. The Claus tail gas enters the tertiary condenser 10 for condensation. The liquid sulfur generated after condensation enters the liquid sulfur pool 14. The separated Claus tail gas enters the tail gas purification unit.

[0054] In the catalytic reaction unit, the process gas generated by the thermal reaction unit enters the first-stage converter 6 and the second-stage converter 9, where, under the action of the catalyst, the following reaction occurs:

[0055] SO2 + 2H2S → 2H2O + 3S;

[0056] COS + H2O → H2S + CO2;

[0057] CS2 + 2H2O → 2H2S + CO2;

[0058] After two stages of Claus catalytic conversion, elemental sulfur is condensed by a condenser and enters liquid sulfur pool 14. The Claus tail gas after the reaction contains trace amounts of elemental sulfur, H2S, SO2, and sulfides such as COS and CS2, and enters the tail gas purification unit.

[0059] A primary heater 5 is installed before the primary converter 6 to control the inlet temperature of the primary converter 5 to 230-250℃.

[0060] A secondary heater 7 is installed before the secondary converter 9 to control the inlet temperature of the secondary converter 7 to 210-240℃.

[0061] The recommended gradation scheme for the first-stage converter 6 is as follows: the upper part is filled with 1 / 3 sulfur recovery catalyst with oxygen removal function, and the lower part is filled with 2 / 3 titanium oxide-based sulfur recovery catalyst with high organic sulfur hydrolysis activity.

[0062] The secondary converter 9 is entirely filled with alumina-based sulfur production catalyst.

[0063] The preferred oxygen-leakage-protected sulfur recovery catalyst is the LS-971 catalyst developed by the Research Institute of Sinopec Qilu Branch. This catalyst protects or mitigates sulfation damage caused by oxygen leakage in the process gas, thereby extending its service life. Furthermore, the oxygen removal process generates significant heat of reaction, increasing the reaction temperature and facilitating the hydrolysis of organic sulfur.

[0064] The preferred titanium dioxide-based sulfur recovery catalyst is the LS-981G catalyst developed by the Research Institute of Sinopec Qilu Branch. The LS-981G catalyst exhibits higher catalytic activity for the hydrolysis of organic sulfides and the Claus reaction of H2S with SO2, reaching near thermodynamic equilibrium. It is insensitive to "O2 poisoning" and has a slow hydrolysis deactivation rate, maintaining relatively stable organic sulfur hydrolysis activity throughout its service life.

[0065] The preferred alumina-based sulfur production catalyst is the LS-02 catalyst developed by the Research Institute of Sinopec Qilu Branch. This catalyst exhibits high Claus activity, strong resistance to thermal and hydrothermal aging, uniform particle size, low wear, and high crushing strength, thus ensuring long-term operation. Furthermore, the catalyst has numerous macropores with a bimodal pore structure, allowing the generated sulfur to rapidly exit the catalyst channels, further enhancing its Claus activity and organic sulfur hydrolysis activity.

[0066] Figure 1 The schematic diagram of the device structure shown indicates that the exhaust gas purification unit includes an exhaust gas heater 11, a hydrogenation reactor 12, a steam generator 13, a mixed gas buffer tank 15, a quench 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.

[0067] In the exhaust gas purification unit, Claus exhaust gas is reheated to 250-280°C by exhaust gas heater 11 and then enters hydrogenation reactor 12. Under the action of hydrogenation catalyst in hydrogenation reactor 12, sulfur-containing compounds are hydrogenated to H2S. Hydrogenated exhaust gas with H2S content less than 2% (v) is cooled by steam generator 13 and then enters mixed gas buffer tank 15 to mix with ultra-low concentration acid gas 22 with H2S content less than 1% (v). The mixed gas then enters quench tower 16 to cool to 25-38°C, and then... The H2S in the absorption tower 17 is countercurrently 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 by 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℃, the temperature at the bottom of the tower is controlled at 115-120℃, and the pressure at the top of the tower is 0.06-0.10 MPa. The regenerated acid gas at the top of the regeneration tower 19 is returned to the sulfur production furnace, and 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 in compliance with emission standards.

[0068] In the exhaust gas purification unit, the Claus exhaust gas generated by the catalytic reaction unit enters the hydrogenation reactor. Under the action of the hydrogenation catalyst, elemental sulfur, SO2, and other substances carried in the exhaust gas are all converted into H2S by hydrogenation, and COS and CS2 are hydrolyzed into H2S. The reaction is as follows:

[0069] S x +xH2→xH2S;

[0070] SO2 + 3H2 → H2S + 2H2O.

[0071] The hydrogenation tail gas containing H2S is cooled by the steam generator 13 and then mixed with ultra-low concentration acid gas in the mixed gas buffer tank 15. The mixed gas enters the quench tower 16 and is cooled by the quench tower 16 before entering the amine liquid absorption tower 17 containing the formulated high-efficiency desulfurization solvent. H2S is absorbed by the amine liquid. The amine-rich 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 emission standards.

[0072] A tail gas heater is installed before the hydrogenation reactor to control the inlet temperature of the hydrogenation reactor at 250-300℃, preferably 250-280℃.

[0073] The hydrogenation reactor 12 is filled with a multifunctional, highly active tail gas hydrogenation catalyst.

[0074] The preferred multifunctional, highly active tail gas hydrogenation catalyst is the LSH-03G catalyst developed by the Research Institute of Sinopec Qilu Branch. This catalyst exhibits excellent low-temperature hydrogenation and hydrolysis activity, as well as CO conversion activity.

[0075] After the hydrogenation tail gas is cooled to 160-170°C by the steam generator 13, the liquid sulfur is separated from the hydrogenation tail gas.

[0076] The mixed gas is a mixture of ultra-low concentration acid gas and hydrogenation tail gas.

[0077] The mixed gas buffer tank 15 can be located anywhere between the steam generator and the quench tower.

[0078] The mixed gas buffer tank 15 can separate liquids such as methanol from ultra-low concentration acid gas.

[0079] The pH value of the quench tower 16 is controlled between 7 and 9.

[0080] The ultra-low concentration acid gas may or may not contain ammonia.

[0081] If the ultra-low concentration acidic gas contains ammonia, the ammonia can be used as a supplementary ammonia injection for the quench water to prevent the pH value of the quench water from decreasing.

[0082] The outlet gas temperature of the quench tower 16 is 25-40℃, preferably 25-38℃.

[0083] The amine-rich liquid at the bottom of the absorption tower 17 enters the regeneration tower for regeneration, and the regenerated acid gas is returned to the sulfur production furnace 3 for recycling as the acid gas source for the sulfur production unit, thus realizing a closed-loop cycle of sulfur resources.

[0084] The temperature at the top of the regeneration tower 19 is controlled at 100-115℃, the temperature at the bottom of the tower is controlled at 115-120℃, and the pressure at the top of the tower is 0.06-0.10 MPa.

[0085] The regenerated acid gas at the top of the regeneration tower 19 is returned to the sulfur production furnace for recycling.

[0086] In the following embodiments of the present invention, the primary heater, secondary heater and tail gas heater in the processing device 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 mixing, electric heating, and heating furnace.

[0087] Example 1

[0088] The method for treating ultra-low concentration acidic gas described in this embodiment employs the method shown in the attached figure. Figure 1 The processing apparatus shown includes the following steps: thermal reaction, catalytic reaction, and tail gas hydrogenation.

[0089] (1) Thermal reaction unit

[0090] Acidic gas 1 containing 65 (v / v)% H2S is partially combusted with air 2 in sulfur-making furnace 3 to convert into SO2. H2S and SO2 undergo a Claus reaction at 1150℃ to generate sulfur-making furnace tail gas. The elemental sulfur in the gas is cooled to 160℃ by primary condenser 4 and then enters liquid sulfur pool 14 to obtain liquid sulfur. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0091] (2) Catalytic reaction unit

[0092] The tail gas from the sulfur production furnace is first heated to 240°C by the primary heater 5, and then enters the primary converter 6 (temperature 310°C, the upper part of the reactor is filled with 1 / 3 LS-971 catalyst and the lower part with 2 / 3 LS-981G catalyst). Under the action of the catalyst, the tail gas of the primary converter is generated and enters the secondary condenser 7 for condensation and separation. The elemental sulfur in it enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 150°C. The separated tail gas of the primary converter is heated to 215°C by the secondary heater 8 and enters the secondary converter 9 (temperature 250°C, the reactor is completely filled with LS-02 catalyst). Under the action of the catalyst, Claus tail gas is generated. 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.

[0093] (3) Exhaust gas hydrogenation unit

[0094] The resulting Claus tail gas is reheated to 250°C by tail gas heater 11 and then enters hydrogenation reactor 12. In hydrogenation reactor 12, under the action of a hydrogenation catalyst, sulfur-containing compounds are hydrogenated to H2S. The hydrogenated tail gas with an H2S content of 1.0 (v)% is cooled by steam generator 13 and then mixed with ultra-low concentration acid gas 22 with an H2S content of 0.9 (v)% in mixed gas buffer tank 15. The mixed gas then enters quench tower 16 to cool to 25°C, and then enters absorption tower. 17. H2S is absorbed countercurrently by the lean amine solution from the bottom of regeneration tower 19. The rich amine solution at the bottom of absorption tower 17 is heated by the lean-rich solution heat exchanger 18 before entering regeneration tower 19 for regeneration. The top temperature of the regeneration tower is 100℃, the bottom temperature is controlled at 115℃, and the top pressure is 0.08 MPa. The regenerated acid gas from the top of the regeneration tower is returned to the sulfur production furnace. The purified tail gas from the top of absorption tower 17 enters the incinerator 20 for combustion. The flue gas after combustion is discharged through chimney 21 in compliance with emission standards (SO2 emission < 50 mg / m³). 3 ).

[0095] Example 2

[0096] The method for treating ultra-low concentration acidic gas described in this embodiment employs the method shown in the attached figure. Figure 1 The processing apparatus shown includes the following steps: thermal reaction, catalytic reaction, and tail gas hydrogenation.

[0097] (1) Thermal reaction unit

[0098] Acidic gas 1 containing 70 (v / v)% H2S is partially combusted with air 2 in sulfur-making furnace 3 to convert into SO2. H2S and SO2 undergo a Claus reaction at 1200℃ to generate sulfur-making furnace tail gas. The elemental sulfur in the gas is cooled to 162℃ by primary condenser 4 and then enters liquid sulfur pool 14 to obtain liquid sulfur. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0099] (2) Catalytic reaction unit

[0100] The tail gas from the sulfur production furnace is first heated to 230°C by the primary heater 5, and then enters the primary converter 6 (temperature 313°C, the upper part of the reactor is filled with 1 / 3 LS-971 catalyst and the lower part with 2 / 3 LS-981G catalyst). Under the action of the catalyst, the tail gas of the primary converter is generated and enters the secondary condenser 7 for condensation and separation. The elemental sulfur in it enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 152°C. The separated tail gas of the primary converter is heated to 210°C by the secondary heater 8 and enters the secondary converter 9 (temperature 245°C, the reactor is completely filled with LS-02 catalyst). Under the action of the catalyst, Claus tail gas is generated. 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.

[0101] (3) Exhaust gas hydrogenation unit

[0102] Claus exhaust gas is reheated to 250°C by exhaust gas heater 11 and then enters hydrogenation reactor 12. In hydrogenation reactor 12, under the action of hydrogenation catalyst, sulfur-containing compounds are hydrogenated to H2S. The hydrogenated exhaust gas with an H2S content of 1.2% (v) is cooled by steam generator 13 and then mixed with ultra-low concentration acid gas 22 with an H2S content of 0.8% (v) in mixed gas buffer tank 15. The mixed gas enters quench tower 16 to cool to 30°C, and then enters absorption tower 1. 7. The H2S is absorbed by the lean amine solution from the bottom of regeneration tower 19 via countercurrent contact. The rich amine solution from the bottom of absorption tower 17 is heated by the lean-rich solution heat exchanger 18 before entering regeneration tower 19 for regeneration. The top temperature of the regeneration tower is 110℃, the bottom temperature is controlled at 117℃, and the top pressure is 0.08 MPa. The regenerated acid gas from the top of the regeneration tower is returned to the sulfur production furnace. The purified tail gas from the top of absorption tower 17 enters the incinerator 20 for combustion. The flue gas after combustion is discharged through chimney 21 in compliance with emission standards (SO2 emission < 50 mg / m³). 3 ).

[0103] Example 3

[0104] The method for treating ultra-low concentration acidic gas described in this embodiment employs the method shown in the attached figure. Figure 1 The processing apparatus shown includes the following steps: thermal reaction, catalytic reaction, and tail gas hydrogenation.

[0105] (1) Thermal reaction unit

[0106] Acidic gas 1 containing 65 (v / v)% H2S is partially combusted with air 2 in sulfur-making furnace 3 to convert into SO2. H2S and SO2 undergo a Claus reaction at 1200℃ to generate sulfur-making furnace tail gas. The elemental sulfur in the gas is cooled to 162℃ by primary condenser 4 and then enters liquid sulfur pool 14 to obtain liquid sulfur. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0107] (2) Catalytic reaction unit

[0108] The tail gas from the sulfur production furnace is first heated to 240°C by the primary heater 5, and then enters the primary converter 6 (temperature 310°C, the upper part of the reactor is filled with 1 / 3 LS-971 catalyst and the lower part with 2 / 3 LS-981G catalyst). Under the action of the catalyst, the tail gas of the primary converter is generated and enters the secondary condenser 7 for condensation and separation. The elemental sulfur in it enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 150°C. The separated tail gas of the primary converter is heated to 215°C by the secondary heater 8 and enters the secondary converter 9 (temperature 250°C, the reactor is completely filled with LS-02 catalyst). Under the action of the catalyst, Claus tail gas is generated. 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.

[0109] (3) Exhaust gas hydrogenation unit

[0110] Claus exhaust gas is reheated to 255°C by exhaust gas heater 11 and then enters hydrogenation reactor 12. In hydrogenation reactor 12, under the action of a hydrogenation catalyst, sulfur-containing compounds are hydrogenated to H2S. The hydrogenated exhaust gas with an H2S content of 0.9% (v) is cooled by steam generator 13 and then mixed with ultra-low concentration acid gas 22 with an H2S content of 0.5% (v) in mixed gas buffer tank 15. The mixed gas then enters quench tower 16 to cool to 28°C, and then enters absorption tower 1. 7. The H2S is absorbed by the lean amine solution from the bottom of regeneration tower 19 via countercurrent contact. The rich amine solution from the bottom of absorption tower 17 is heated by the lean-rich solution heat exchanger 18 before entering regeneration tower 19 for regeneration. The top temperature of the regeneration tower is 108℃, the bottom temperature is controlled at 116℃, and the top pressure is 0.07 MPa. The regenerated acid gas from the top of the regeneration tower is returned to the sulfur production furnace. The purified tail gas from the top of absorption tower 17 enters the incinerator 20 for combustion. The flue gas after combustion is discharged through chimney 21 in compliance with emission standards (SO2 emission < 50 mg / m³). 3 ).

[0111] Example 4

[0112] The method for treating ultra-low concentration acidic gas described in this embodiment employs the method shown in the attached figure. Figure 1 The processing apparatus shown includes the following steps: thermal reaction, catalytic reaction, and tail gas hydrogenation.

[0113] (1) Thermal reaction unit

[0114] Acidic gas 1 containing 65 (v / v)% H2S and air 2 are partially combusted in sulfur-making furnace 3 to convert into SO2. H2S and SO2 undergo a Claus reaction at 1200℃ to generate sulfur-making furnace tail gas. The elemental sulfur in the gas is cooled to 160℃ by primary condenser 4 and then enters liquid sulfur pool 14 to obtain liquid sulfur. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0115] (2) Catalytic reaction unit

[0116] The tail gas from the sulfur production furnace is first heated to 245°C by the primary heater 5, and then enters the primary converter 6 (temperature 320°C, the upper part of the reactor is filled with 1 / 3 LS-971 catalyst and the lower part with 2 / 3 LS-981G catalyst). Under the action of the catalyst, the tail gas of the primary converter is generated and enters the secondary condenser 7 for condensation and separation. The elemental sulfur in it enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 155°C. The separated tail gas of the primary converter is heated to 210°C by the secondary heater 8 and enters the secondary converter 9 (temperature 245°C, the entire reactor is filled with LS-02 catalyst). Under the action of the catalyst, Claus tail gas is generated. 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.

[0117] (3) Exhaust gas hydrogenation unit

[0118] Claus exhaust gas is reheated to 260°C by exhaust gas heater 11 and then enters hydrogenation reactor 12. In hydrogenation reactor 12, under the action of hydrogenation catalyst, sulfur-containing compounds are hydrogenated to H2S. The hydrogenated exhaust gas with an H2S content of 0.7% (v) is cooled by steam generator 13 and then mixed with ultra-low concentration acid gas 22 with an H2S content of 0.9% (v) in mixed gas buffer tank 15. The mixed gas enters quench tower 16 to be cooled to 32°C, and then enters absorption tower 1. 7. The H2S is absorbed by the lean amine solution from the bottom of regeneration tower 19 via countercurrent contact. The rich amine solution from the bottom of absorption tower 17 is heated by the lean-rich solution heat exchanger 18 before entering regeneration tower 19 for regeneration. The top temperature of the regeneration tower is 109℃, the bottom temperature is controlled at 118℃, and the top pressure is 0.07 MPa. The regenerated acid gas from the top of the regeneration tower is returned to the sulfur production furnace. The purified tail gas from the top of absorption tower 17 enters the incinerator 20 for combustion. The flue gas after combustion is discharged through chimney 21 in compliance with emission standards (SO2 emission < 50 mg / m³). 3 ).

[0119] Example 5

[0120] The method for treating ultra-low concentration acidic gas described in this embodiment employs the method shown in the attached figure. Figure 1 The processing apparatus shown includes the following steps: thermal reaction, catalytic reaction, and tail gas hydrogenation.

[0121] (1) Thermal reaction unit

[0122] Acidic gas 1 containing 75 (v / v)% H2S is partially combusted with air 2 in sulfur-making furnace 3 to convert into SO2. H2S and SO2 undergo a Claus reaction at 1250℃ to generate sulfur-making furnace tail gas. The elemental sulfur in the gas is cooled to 165℃ by primary condenser 4 and then enters liquid sulfur pool 14 to obtain liquid sulfur. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0123] (2) Catalytic reaction unit

[0124] The tail gas from the sulfur production furnace is first heated to 245°C by the primary heater 5, and then enters the primary converter 6 (temperature 325°C, the upper part of the reactor is filled with 1 / 3 LS-971 catalyst and the lower part with 2 / 3 LS-981G catalyst). Under the action of the catalyst, the tail gas of the primary converter is generated and enters the secondary condenser 7 for condensation and separation. The elemental sulfur in it enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 153°C. The tail gas of the primary converter after separation is heated to 215°C by the secondary heater 8 and enters the secondary converter 9 (temperature 245°C, the entire reactor is filled with LS-02 catalyst). Under the action of the catalyst, Claus tail gas is generated. 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.

[0125] (3) Exhaust gas hydrogenation unit

[0126] Claus exhaust gas is reheated to 280°C by exhaust gas heater 11 and then enters hydrogenation reactor 12. In hydrogenation reactor 12, under the action of hydrogenation catalyst, sulfur-containing compounds are hydrogenated to H2S. The hydrogenated exhaust gas with an H2S content of 1.5% (v) is cooled by steam generator 13 and then mixed with ultra-low concentration acid gas 22 with an H2S content of 0.5% (v) in mixed gas buffer tank 15. The mixed gas then enters quench tower 16 to cool to 25°C, and then enters absorption tower 1. 7. The H2S is absorbed by the lean amine solution from the bottom of regeneration tower 19 via countercurrent contact. The rich amine solution from the bottom of absorption tower 17 is heated by the lean-rich solution heat exchanger 18 before entering regeneration tower 19 for regeneration. The top temperature of the regeneration tower is 115℃, the bottom temperature is controlled at 120℃, and the top pressure is 0.09 MPa. The regenerated acid gas from the top of the regeneration tower is returned to the sulfur production furnace. The purified tail gas from the top of absorption tower 17 enters the incinerator 20 for combustion. The flue gas after combustion is discharged through chimney 21 in compliance with emission standards (SO2 emission < 50 mg / m³). 3 ).

[0127] Comparative Example 1

[0128] The method for treating ultra-low concentration acidic gas described in this comparative example adopts the method shown in the attached figure. Figure 2 The processing device shown is used to process the ultra-low concentration acid gas, which is the same as that in Example 1.

[0129] The only 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 production furnace for treatment, while the other processes are the same as in Example 1.

[0130] This treatment method requires preheating the air, which significantly increases the energy consumption of the equipment. In severe cases, it may cause the sulfur production furnace to shut down. Furthermore, CO2 in ultra-low concentration acid gas will generate a large amount of CO in the sulfur production furnace, causing the CO emission of the sulfur recovery unit to fail to meet the standards.

[0131] Comparative Example 2

[0132] The method for treating the ultra-low concentration acid gas described in this comparative example involves burning the ultra-low concentration acid gas (composition same as in Example 5) through a flare and then directly releasing it into the atmosphere, with an SO2 emission concentration of 5000 mg / m³. 3 It seriously pollutes the environment.

[0133] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for treating low-concentration acidic gas, characterized in that, Includes the following steps: (1) Mix the low-concentration acid gas to be treated with Claus hydrogenation tail gas to obtain a mixed gas; (2) The mixture is condensed; (3) The condensed exhaust gas is absorbed by amine solution; (4) The purified exhaust gas generated after absorbing the amine liquid is incinerated and then discharged; The H2S content in the Claus hydrogenation tail gas is less than 2% (v)%. The low-concentration acidic gas contains less than 1% (v) of H2S and also contains NH3.

2. The method for treating low-concentration acidic gas according to claim 1, characterized in that, In step (2), the condensation step includes the step of introducing the mixed gas into the quench tower; The pH value of the quench tower is controlled to be 7-9; the outlet gas temperature of the quench tower is controlled to be 25-40℃.

3. The method for treating low-concentration acidic gas according to claim 1, characterized in that, In step (3), the amine absorption step includes the step of introducing the quenched tail gas into an absorption tower containing desulfurization solvent for H2S absorption.

4. The method for treating low-concentration acidic gas according to claim 3, characterized in that, Step (3) also includes the step of introducing the rich amine liquid generated at the bottom of the absorption tower into a regeneration tower for regeneration; In the regeneration step, the temperature at the top of the regeneration tower is controlled at 100-115℃, the temperature at the bottom of the tower is controlled at 115-120℃, and the pressure at the top of the tower is controlled at 0.06-0.10 MPa.

5. The method for treating low-concentration acidic gas according to claim 1, characterized in that, Step (1) further includes the step of separating the liquid in the low-concentration acid gas using a mixed gas buffer tank.

6. The method for treating low-concentration acidic gas according to any one of claims 1-5, characterized in that, The method also includes the step of preparing Claus hydrogenation tail gas; The Claus hydrogenation tail gas is Claus hydrogenation tail gas obtained from the sulfur recovery process.

7. The method for treating low-concentration acidic gas according to claim 6, characterized in that, The preparation steps of the Claus hydrogenation tail gas include the steps of using acidic gas from the sulfur process as raw material, recovering sulfur through thermal reaction and catalytic reaction, and treating the generated Claus tail gas with hydrogen.

8. The method for treating low-concentration acidic gas according to claim 1, characterized in that, The treatment method employs a low-concentration acid gas treatment device, comprising a pipeline-connected mixed gas buffer tank, a quench tower, an absorption tower, and an incinerator; wherein, The mixed gas buffer tank is used to mix the Claus hydrogenation tail gas with the low-concentration acid gas; The quench tower is used to condense the mixed gas. The absorption tower is used to absorb the quenched tail gas with amine solution; The incinerator is used to burn the purified gas generated after the amine solution is absorbed.

9. The method for treating low-concentration acidic gas according to claim 8, characterized in that, The processing apparatus includes a sulfur recovery unit and a mixed gas buffer tank located before the quench tower of the sulfur recovery unit for mixing the Claus hydrogenation tail gas with the low-concentration acid gas. The mixed gas buffer tank is located between the steam generator and the quench tower of the sulfur recovery unit.

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