Process system and process method for treating hydrogen sulfide-containing acid gas

Abstract

A process system and process method for treating hydrogen sulfide-containing acid gas. The process system comprises a sulfur recovery unit, a tail gas treatment unit having an acid gas concentration function, and a flue gas alkaline scrubbing unit. The method comprises: subjecting sulfur-containing tail gas to concentration treatment by means of an absorption column (1) of the tail gas treatment unit, and then introducing same into the sulfur recovery unit to undergo a Claus reaction for separation, so as to obtain sulfur and sulfur recovery tail gas; introducing the sulfur recovery tail gas into the tail gas treatment unit, successively carrying out combustion and hydrotreating, and introducing the obtained gas into the absorption column (1) of the tail gas treatment unit; and in the tail gas treatment unit, introducing gas absorbed by the absorption column (1) into the flue gas alkaline scrubbing unit, and successively carrying out incineration and alkaline scrubbing, so as to discharge desulfurized gas. The content of SO2 in the tail gas treated by the process system is ≤50 mg / Nm3, and the requirements for full-period standard reaching of sulfur dioxide emission of tail gas during startup, shutdown and normal operations can be satisfied.

Description

A process system and method for treating acid gas containing hydrogen sulfide Technical Field

[0001] The present invention belongs to the field of tail gas treatment, and relates to an acid gas concentration, sulfur recovery and tail gas treatment system suitable for low hydrogen sulfide concentration acid gas containing organic sulfur, and specifically to a process system and process method for treating hydrogen sulfide-containing acid gas. Background Art

[0002] Natural gas has been increasingly used in modern industrial production and life. However, most natural gas extracted from gas fields contains acidic components such as hydrogen sulfide, organic sulfur, and carbon dioxide. These acidic components can cause problems such as corrosion of transportation and downstream processing equipment and pipelines, as well as environmental pollution. Therefore, natural gas is generally subjected to amine desulfurization and decarbonization treatment. The acid gas generated by amine solution regeneration must be treated to meet environmental protection requirements before it can be discharged.

[0003] If the concentration of hydrogen sulfide in the acid gas is high (>50 mol%), the acid gas treatment process of Claus + tail gas treatment can often be directly adopted. The acid gas can be directly fed into the sulfur recovery unit, mixed with air in a specific ratio, burned in the combustion furnace and reacted in the downstream reactor. The hydrogen sulfide and organic sulfur are converted into elemental sulfur through the Claus reaction. In combination with the tail gas treatment unit, the sulfur recovery rate can reach more than 99.5%, and the generated tail gas can also meet environmental protection requirements.

[0004] When the concentration of hydrogen sulfide in the acid gas is low (15 mol% to 50 mol%), if all the acid gas enters the combustion furnace, the combustion furnace will find it difficult to maintain a stable combustion temperature. In this case, the Claus split process is used. This process, based on the principle of the Claus reaction, only introduces 1 / 3 of the acid gas into the combustion furnace for combustion, converts it into sulfur dioxide, and then mixes it with the remaining acid gas to undergo the Claus reaction. This process can maintain the combustion furnace temperature, but when the acid gas contains heavy hydrocarbons, it may cause problems such as catalyst contamination.

[0005] When the hydrogen sulfide concentration in the acid gas is even lower, an acid gas concentration system can be added before the Claus unit. This system leverages the selective absorption of hydrogen sulfide by amines to concentrate the acid gas before it enters the sulfur recovery unit. However, this process requires the addition of a concentration tower and regeneration tower to the Claus + tail gas treatment unit, making the process complex. When the acid gas also contains organic sulfur, the amines are unable to absorb it, and the organic sulfur is discharged into the atmosphere with the tail gas, causing excessive tail gas emissions and environmental pollution. Alternatively, a process involving direct acid gas incineration followed by alkaline washing can be employed. This alkaline washing and absorption process utilizes a chemical reaction, using alkaline solution to absorb the acid gas converted to sulfur dioxide by incineration. This process is rapid, and the resulting tail gas meets high environmental standards. However, this process suffers from high alkaline consumption and is only suitable for treating acid gas with extremely low sulfur content.

[0006] In response to the above technical problems, increasing the concentration of hydrogen sulfide in acid gas and treating the organic sulfur in the acid gas while achieving ultra-low exhaust emissions has become a current direction for improving the process.

[0007] Summary of the Invention

[0008] In order to solve the above problems, the present invention provides a process system and process method for treating hydrogen sulfide acid gas, wherein the SO2 content in the tail gas treated by the process system is ≤50mg / Nm 3 , meet the special emission limit requirements in the "Petroleum Refining Industry Pollutant Emission Standard" (GB13570-2015), and can meet the requirements for exhaust sulfur dioxide emissions to meet the standards at all times during start-up, shutdown and normal operation.

[0009] In order to achieve the above-mentioned object, the present invention provides a process system for treating hydrogen sulfide-containing acid gas, which includes a sulfur recovery unit, a tail gas treatment unit with an acid gas concentration function, and a flue gas alkali washing unit; the tail gas treatment unit is provided with an online burner, a hydrogenation reactor, an absorption tower, a lean-rich liquid heat exchanger, a regeneration tower, and a regeneration tower reflux tank, the gas outlet of the sulfur recovery unit is connected to the inlet of the online burner, the outlet of the online burner is connected to the inlet of the hydrogenation reactor, the outlet of the hydrogenation reactor is connected to the middle and lower inlet of the absorption tower, the sulfur-containing tail gas enters the tail gas treatment unit through the bottom inlet of the absorption tower, the bottom outlet of the absorption tower is connected to the upper inlet of the regeneration tower through the lean-rich liquid heat exchanger, the upper outlet of the regeneration tower is connected to the upper inlet of the regeneration tower and the gas inlet of the sulfur recovery unit through the regeneration tower reflux tank, the bottom outlet of the regeneration tower is connected to the upper inlet of the absorption tower through the lean-rich liquid heat exchanger, and the upper outlet of the absorption tower is connected to the gas inlet of the flue gas alkali washing unit.

[0010] According to a specific embodiment of the present invention, preferably, the process system for treating hydrogen sulfide-containing acid gas comprises a sulfur recovery unit, a tail gas treatment unit with an acid gas concentration function, and a flue gas alkali washing unit;

[0011] The sulfur recovery unit is provided with a main combustion furnace and a Claus treatment device. The upper outlet of the regeneration tower is connected to the inlet of the main combustion furnace through the regeneration tower reflux tank. The outlet of the main combustion furnace is connected to the Claus treatment device. The gas outlet of the Claus treatment device is connected to the inlet of the online combustion furnace of the tail gas treatment unit. The Claus treatment device is provided with a sulfur condenser, a reheat furnace, and a Claus reactor.

[0012] The tail gas treatment unit is provided with an online combustion furnace, a hydrogenation reactor, an absorption tower, a lean and rich liquid heat exchanger, a regeneration tower, and a regeneration tower reflux tank. The gas outlet of the Claus treatment device is connected to the inlet of the online combustion furnace, the outlet of the online combustion furnace is connected to the inlet of the hydrogenation reactor, the outlet of the hydrogenation reactor is connected to the middle and lower inlet of the absorption tower, the sulfur-containing tail gas enters the tail gas treatment unit through the bottom inlet of the absorption tower, the bottom outlet of the absorption tower is connected to the upper inlet of the regeneration tower through the lean and rich liquid heat exchanger, the upper outlet of the regeneration tower is respectively connected to the upper inlet of the regeneration tower and the main combustion furnace inlet of the sulfur recovery unit through the regeneration tower reflux tank, the bottom outlet of the regeneration tower is connected to the upper inlet of the absorption tower through the lean and rich liquid heat exchanger, and the upper outlet of the absorption tower is connected to the inlet of the tail gas incinerator of the flue gas alkali washing unit;

[0013] The flue gas alkali washing unit is provided with a tail gas incinerator, a flue gas heat exchanger, an alkali washing tower, and a purified flue gas separator. The upper outlet of the absorption tower is connected to the inlet of the tail gas incinerator, the outlet of the tail gas incinerator is connected to the inlet of the alkali washing tower through the flue gas heat exchanger, the upper outlet of the alkali washing tower is connected to the flue gas heat exchanger through the purified flue gas separator, the flue gas heat exchanger leads to the atmosphere, and the liquid outlet of the purified flue gas separator is connected to the alkali washing tower.

[0014] According to a specific embodiment of the present invention, preferably, in the tail gas treatment unit, a rich liquid pump is provided between the bottom outlet of the absorption tower and the lean and rich liquid heat exchanger, an acid gas air cooler and an acid gas aftercooler are provided between the upper outlet of the regeneration tower and the regeneration tower reflux tank, a lean liquid pump, a lean liquid air cooler and a lean liquid aftercooler are provided between the lean and rich liquid heat exchanger and the upper inlet of the absorption tower, a regeneration tower reflux pump is provided between the regeneration tower reflux tank and the upper inlet of the regeneration tower; and a regeneration tower reboiler is provided at the lower part of the regeneration tower.

[0015] According to a specific embodiment of the present invention, preferably, in the sulfur recovery unit, a waste heat boiler is provided between the outlet of the main combustion furnace and the Claus treatment device, and the Claus treatment device includes a primary sulfur condenser, a primary reheat furnace, a primary Claus reactor, a secondary sulfur condenser, a secondary reheat furnace, a secondary Claus reactor, and a tertiary sulfur condenser, and the gas outlet of the tertiary sulfur condenser is connected to the inlet of the online combustion furnace of the tail gas treatment unit.

[0016] According to a specific embodiment of the present invention, preferably, a waste heat boiler and a quenching tower are provided between the outlet of the hydrogenation reactor and the lower inlet of the absorption tower.

[0017] According to a specific embodiment of the present invention, preferably, a flue gas waste heat boiler is provided between the outlet of the tail gas incinerator and the flue gas heat exchanger, the flue gas heat exchanger is connected to a chimney, and the bottom outlet of the alkali washing tower is connected to the upper inlet of the alkali washing tower through a desulfurization liquid circulation pump.

[0018] According to a specific embodiment of the present invention, preferably, in the tail gas treatment unit, the acid gas is discharged from the top of the regeneration tower reflux tank, part of the acid gas enters the bottom of the absorption tower through the super concentration line, and the remaining acid gas enters the main combustion furnace of the sulfur recovery unit.

[0019] According to a specific embodiment of the present invention, preferably, the alkali washing tower is provided with a spray section, and a packing section is provided on the upper part of the spray section.

[0020] The present invention also provides a process for desulfurizing sulfur-containing tail gas using the above-mentioned process system for treating hydrogen sulfide-containing acid gas.

[0021] According to a specific embodiment of the present invention, preferably, the sulfur-containing tail gas is concentrated in the absorption tower of the tail gas treatment unit and then enters the sulfur recovery unit, where a Claus reaction occurs to separate sulfur and sulfur-recovered tail gas. The sulfur-recovered tail gas enters the online combustion furnace of the tail gas treatment unit, where combustion and hydrogenation treatment are carried out in sequence, and the resulting gas enters the absorption tower; in the tail gas treatment unit, the gas absorbed by the absorption tower enters the flue gas alkali washing unit, where incineration and alkali washing are carried out in sequence, and desulfurized gas is discharged.

[0022] According to a specific embodiment of the present invention, preferably, in the tail gas treatment unit, sulfur-containing tail gas is introduced from the bottom of the absorption tower, and rich liquid is obtained after being absorbed by the countercurrent absorption liquid. The rich liquid passes through the rich liquid pump and the lean-rich liquid heat exchanger from the bottom of the absorption tower to enter the regeneration tower. The lean liquid obtained after the regeneration treatment passes through the lean-rich liquid heat exchanger, the lean liquid pump, the lean liquid air cooler, and the lean liquid aftercooler from the bottom of the regeneration tower to enter the top of the absorption tower; the acid gas obtained after the regeneration treatment passes through the acid gas air cooler and the acid gas aftercooler from the top of the regeneration tower to enter the regeneration tower reflux tank. The separated condensed water is pressurized by the regeneration tower reflux pump from the bottom of the regeneration tower and enters the regeneration tower. The acid gas is discharged from the top of the regeneration tower reflux tank and enters the sulfur recovery unit.

[0023] In the above-mentioned tail gas treatment unit, hydrogen sulfide-containing acid gas first enters the absorption tower from the bottom of the absorption tower, where it comes into contact with a highly selective composite formula amine liquid. Due to the amine liquid's higher selectivity for hydrogen sulfide, it absorbs most of the hydrogen sulfide and part of the carbon dioxide in the acid gas. The unabsorbed carbon dioxide and organic sulfur components in the acid gas are discharged from the top of the absorption tower and sent to the tail gas incinerator. The rich liquid flowing out of the bottom of the absorption tower is heated in a lean-rich liquid heat exchanger and then enters the regeneration tower. It is countercurrently contacted with the amine liquid vapor flowing from the bottom to the top of the tower for regeneration, decomposing hydrogen sulfide and carbon dioxide gases. The regeneration heat is provided by a reboiler at the bottom of the tower. The hot lean liquid is drawn from the bottom of the regeneration tower at a temperature of approximately 125°C, cooled by heat exchange with the rich liquid in the lean-rich amine liquid heat exchanger, cooled to approximately 35°C by a lean amine liquid air cooler and a lean amine liquid aftercooler, and then pumped into a filtration system by a lean liquid pump to remove mechanical impurities and degradation products in the solution. Finally, it enters the absorption tower, completing the circulation of the entire solution system. The acid gas, at approximately 110°C, exiting the top of the regeneration tower is cooled to approximately 35°C via an acid gas air cooler and an acid gas aftercooler before entering the regeneration tower reflux tank. The separated acid gas with a high hydrogen sulfide concentration is sent to the sulfur recovery unit, and the separated acidic condensed water is pumped to the top of the regeneration tower for reflux by the regeneration tower reflux pump. The present invention incorporates a "super-concentration line" on the acid gas pipeline to the sulfur recovery unit. When the acid gas concentration needs to be further increased, a portion of the high-concentration acid gas can be introduced into the absorption tower as concentrated gas, increasing the hydrogen sulfide concentration in the absorption tower acid gas and further improving the selectivity of the amine solution, thereby further increasing the concentration of the acid gas sent to the sulfur recovery unit.

[0024] According to a specific embodiment of the present invention, preferably, in the sulfur recovery unit, the acid gas discharged from the tail gas treatment unit enters the main combustion furnace for Claus reaction to produce process gas containing elemental sulfur. The process gas containing elemental sulfur is discharged from the main combustion furnace, passes through the waste heat boiler and the first-stage sulfur condenser, is cooled to obtain liquid sulfur and is discharged from the bottom of the first-stage sulfur condenser, and the remaining process gas is discharged from the upper part of the first-stage sulfur condenser and then enters the first-stage reheat furnace and the first-stage Claus reactor in sequence to produce process gas containing elemental sulfur. The process gas containing elemental sulfur is discharged from the lower part of the first-stage Claus reactor and enters the second-stage sulfur condenser, is cooled to obtain liquid sulfur and is discharged from the bottom of the second-stage sulfur condenser, and the remaining process gas enters the second-stage reheat furnace and the second-stage Claus reactor from the upper part to produce process gas containing elemental sulfur. The process gas containing elemental sulfur is discharged from the lower part of the second-stage Claus reactor and enters the third-stage sulfur condenser, is cooled to obtain liquid sulfur and is discharged from the bottom of the third-stage sulfur condenser, and the remaining tail gas is discharged from the upper part of the third-stage sulfur condenser and enters the tail gas treatment unit.

[0025] In the above-mentioned sulfur recovery unit, acid gas with high hydrogen sulfide concentration enters the main combustion furnace of the sulfur recovery unit. By adjusting the air ratio, the Claus reaction begins to occur in the combustion furnace, and part of the hydrogen sulfide begins to be converted into elemental sulfur. The process gas coming out of the combustion furnace enters the waste heat boiler and the first-stage sulfur cooler for cooling, and after the generated sulfur is separated, the process gas enters the first-stage reheat furnace. The process gas heated by the first-stage reheat furnace enters the first-stage Claus reactor and further undergoes the Claus reaction under the action of the catalyst. The process gas after the reaction enters the second-stage condenser for condensation and separation of sulfur. The separated process gas enters the second-stage Claus reactor for further reaction, and then enters the third-stage condenser to separate the sulfur. The tail gas generated by the third-stage condensation enters the tail gas treatment unit.

[0026] According to a specific embodiment of the present invention, preferably, in the tail gas treatment unit, the tail gas discharged from the sulfur recovery unit enters the online combustion furnace for combustion, then enters the hydrogenation reactor for hydrogenation reaction, then passes through the waste heat boiler and the quenching tower, and finally is discharged from the top of the quenching tower and enters the middle and lower part of the absorption tower.

[0027] In the exhaust gas treatment unit, exhaust gas from the sulfur recovery unit is mixed with combustion gas in an online combustion furnace and heated to 280°C. The mixed process gas then enters the hydrogenation reactor, where the majority of the sulfides in the process gas are reduced to hydrogen sulfide. In the waste heat boiler, the process gas is cooled to 170°C before entering a quench tower, where it is further cooled to 35°C by countercurrent contact with cooling water. The cooled gas then enters the absorption tower from the lower middle section, where it mixes with low-concentration acid gas entering from the bottom of the tower. Together, they come into contact with amine liquid, absorbing the hydrogen sulfide in the process gas.

[0028] According to a specific embodiment of the present invention, preferably, in the flue gas alkali washing unit, the gas absorbed by the absorption tower enters the tail gas incinerator from the top of the absorption tower to generate flue gas, and the flue gas enters the flue gas waste heat boiler, the flue gas heat exchanger, and the alkali washing tower in sequence. The flue gas after alkali washing is discharged from the top of the alkali washing tower, enters the purified flue gas separator tank and the flue gas heat exchanger in sequence, and is finally discharged through the chimney. The desulfurization liquid is discharged from the bottom of the alkali washing tower and enters the alkali washing tower through the desulfurization liquid circulation pump or is discharged as waste liquid.

[0029] To address the technical issue of organic sulfur in acid gas not being absorbed by the amine solution, resulting in excessive emissions, a flue gas alkali scrubbing unit was installed. Exhaust gas containing organic sulfur and trace amounts of hydrogen sulfide, generated by the exhaust treatment unit's absorption tower, enters the exhaust gas incinerator and is incinerated at 760°C. The resulting sulfur dioxide-containing flue gas is cooled by a flue gas waste heat boiler and a flue gas heat exchanger before entering the bottom of the alkali scrubbing tower. This flue gas then countercurrently contacts atomized desulfurization liquid sprayed from a solid cone nozzle, absorbing sulfur dioxide while cooling the flue gas. The cooled flue gas then enters the packing section of the alkali scrubbing tower, where it further countercurrently contacts the desulfurization liquid to further remove sulfur dioxide. The purified flue gas passes through a demister at the top of the alkali scrubbing tower, where most of the entrained mist is removed. The purified flue gas then enters a purified flue gas separator tank. Finally, it is heated by a flue gas heat exchanger before being discharged into the atmosphere through a chimney. The pH of the desulfurization liquid is controlled by injecting a constant concentration of NaOH solution into the bottom of the alkali scrubbing tower. An oxidation section is also installed at the bottom of the caustic washing tower, allowing a certain amount of air to be introduced to reduce the COD value of the wastewater to meet discharge requirements. Most of the liquid at the bottom outlet of the caustic washing tower is returned to the caustic washing tower as circulating liquid through the desulfurization liquid circulation pump, and a small amount is discharged through the sewage discharge device and enters the water treatment system.

[0030] According to a specific embodiment of the present invention, preferably, the pH value of the bottom circulating liquid at the bottom of the alkali washing tower is 6.2-8.2.

[0031] According to a specific embodiment of the present invention, preferably, the hydrogen sulfide content in the sulfur-containing tail gas is ≤15 mol%.

[0032] According to a specific embodiment of the present invention, preferably, the H2S concentration of the acid gas entering the sulfur recovery unit can be increased to above 50 mol%.

[0033] According to a specific embodiment of the present invention, preferably, the sulfur dioxide content in the flue gas finally discharged by the desulfurization method of the sulfur-containing tail gas is ≤50mg / Nm 3 .

[0034] According to a specific embodiment of the present invention, preferably, the amine liquid used in the absorption tower in the tail gas treatment unit is composed of 97 parts of MDEA, 1-2 parts of phosphoric acid, 0.5-1 parts of corrosion inhibitor, 0.5-1 parts of defoaming agent, and water, calculated by weight.

[0035] According to a specific embodiment of the present invention, preferably, the mass concentration of the amine solution is 40-45%.

[0036] According to a specific embodiment of the present invention, preferably, the corrosion inhibitor includes one or a combination of two or more of imidazolyl dithiourea, 2-amino-imidazolidinone, di(propynyloxymethyl)isopropylbenzyl ammonium chloride, and di(propynyloxymethyl)butylbenzyl ammonium chloride.

[0037] According to a specific embodiment of the present invention, preferably, the defoaming agent includes polyether-modified silicone oil.

[0038] The process system for treating hydrogen sulfide acid gas of the present invention can be applied to the treatment of hydrogen sulfide acid gas in the processes of petroleum refining, chemical industry, natural gas processing, etc. It can not only treat acid gas with hydrogen sulfide concentration lower than 15 mol%, which is difficult to treat by conventional sulfur recovery + tail gas treatment process, but also treat acid gas with hydrogen sulfide concentration higher than 15 mol%, especially the treatment of acid gas with hydrogen sulfide concentration ≤15 mol% containing organic sulfur. The SO2 content in the tail gas after treatment is ≤50 mg / Nm 3 , meeting the special emission limit requirements of the "Petroleum Refining Industry Pollutant Emission Standard" (GB13570-2015), and can meet the requirements for full-time compliance of exhaust sulfur dioxide emissions during start-up, shutdown, and normal operation. Compared with the existing technology, the present invention has the following positive effects:

[0039] (1) The present invention introduces low-concentration acid gas and tail gas generated by the sulfur recovery unit into the same absorption tower, so that the absorption tower has the dual functions of acid gas concentration and tail gas treatment, avoiding the need for a separate concentration tower, which is beneficial to reducing the device footprint and the number of equipment;

[0040] Acid gas and sulfur recovery tail gas enter the absorption tower from different positions (acid gas enters from the bottom of the tower, tail gas enters from the middle and lower part of the tower), which helps to reduce the absorption of carbon dioxide by amine liquid and enhance the concentration effect;

[0041] (2) The present invention is equipped with a "super concentration line". When the acid gas concentration needs to be further increased, part of the high-concentration acid gas can be introduced into the absorption tower as concentrated gas to increase the concentration of hydrogen sulfide in the acid gas in the absorption tower, further improve the selectivity of the amine solution, and thus further increase the concentration of the acid gas sent to the sulfur recovery unit;

[0042] (3) The present invention adds an alkaline washing system on the basis of the process of sulfur recovery + reduction absorption tail gas treatment, adopts NaOH solution as absorbent for chemical absorption, and the alkaline washing tower adopts a combination of one-stage spraying + two-stage fillers. The desulfurization liquid with desulfurization function is divided into two streams and enters the alkaline washing tower from the spraying section and the lower filler. The sulfur-containing flue gas enters from the lower part of the spraying section and contacts with the desulfurization liquid. The temperature drops rapidly, and most of the sulfur dioxide in the flue gas is rapidly absorbed. After that, the low-temperature flue gas enters the lower filler and further contacts with the desulfurization liquid. The remaining sulfur dioxide in the flue gas is further absorbed. Finally, the flue gas enters the uppermost filler and contacts with the water flowing into the top of the tower. The water replenishment here can maintain the liquid level of the alkaline washing tower, maintain the concentration of the desulfurization liquid, and wash away the desulfurization liquid entrained in the flue gas. The present invention also sets a flue gas separator downstream of the alkaline washing tower to further separate the liquid entrained in the flue gas, thereby avoiding the waste of alkaline liquid and corrosion of the downstream heat exchanger to a great extent. This process has a rapid and thorough reaction. By adjusting the injection rate of alkali solution, the requirements for ultra-low sulfur dioxide emissions in tail gas can be met. This solves the technical problem that low hydrogen sulfide concentration acid gas also contains organic sulfur, which cannot be absorbed by the amine solution used for concentration, resulting in substandard tail gas. At the same time, it avoids the waste of alkali solution.

[0043] (4) During the desulfurization process of the start-up and shutdown device, since the sulfur recovery device and the tail gas treatment device are not put into operation or are not running smoothly, the traditional sulfur recovery + tail gas treatment process can only send the sulfur-containing acid gas into the incinerator for direct incineration and conversion into sulfur dioxide before discharge. The tail gas cannot meet the emission standards during the start-up and shutdown process, causing environmental pollution. The present invention can put into operation an alkali washing system. The acid gas generated during the desulfurization process of the device is burned in the incinerator and then enters the alkali washing system. By adjusting the injection amount of the alkali solution, the absorption capacity is improved, and the sulfur dioxide is absorbed before the tail gas is discharged through the chimney, so as to meet the requirements of the tail gas sulfur dioxide at all times. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a process flow chart for treating acid gas containing hydrogen sulfide. DETAILED DESCRIPTION

[0045] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0046] The present invention provides a process system for treating acid gas containing hydrogen sulfide, as shown in Figure 1, which comprises: an absorption tower 1, an exhaust gas incinerator 2, a flue gas waste heat boiler 3, a rich liquid pump 4, a lean and rich liquid heat exchanger 5, a regeneration tower 6, an acid gas air cooler 7, an acid gas aftercooler 8, a regeneration tower reflux tank 9, a regeneration tower reflux pump 10, a lean liquid pump 11, a lean liquid air cooler 12, a lean liquid aftercooler 13, a regeneration tower reboiler 14, a main combustion furnace 15, a waste heat boiler 16, a first stage Sulfur condenser 17, primary reheat furnace 18, primary Claus reactor 19, secondary sulfur condenser 20, secondary reheat furnace 21, secondary Claus reactor 22, tertiary sulfur condenser 23, online combustion furnace 24, hydrogenation reactor 25, waste heat boiler 26, quenching tower 27, flue gas heat exchanger 28, alkali washing tower 29, desulfurization liquid circulation pump 30, purified flue gas separator 31, chimney 32, etc. The specific process flow of desulfurization using this system is as follows:

[0047] (1) Acid gas with low hydrogen sulfide concentration (35°C, 60 kPag, hydrogen sulfide content of 11 mol%) containing organic sulfur enters absorption tower 1 from the bottom of absorption tower 1 and contacts with lean liquid entering from the top of absorption tower 1 in countercurrent flow. Most of the hydrogen sulfide and part of the carbon dioxide in the acid gas are absorbed by the lean liquid. The tail gas after absorption is discharged from the top of absorption tower 1, and the rich liquid that absorbs the acid gas is discharged from the bottom of absorption tower 1;

[0048] The amine solution used is prepared by the following steps: 97% MDEA, 1% phosphoric acid, 1% 2-amino-imidazolidinone, and 1% polyether modified silicone oil are mixed according to mass fraction; and the mixture is diluted with water to prepare an aqueous solution with a mass concentration of 45%.

[0049] (2) The rich liquid described in step (1) is pressurized by the rich liquid pump 4, and then heated to 95°C by the rich-lean liquid heat exchanger 5 before entering the regeneration tower 6. The acid gas is discharged from the top of the regeneration tower 6, and the regenerated lean liquid is discharged from the bottom of the regeneration tower 6.

[0050] (3) The lean liquid described in step (2) is cooled by the lean-rich liquid heat exchanger 5, pressurized by the lean liquid pump 11, and further cooled to 35° C. by the lean liquid air cooler 12 and the lean liquid aftercooler 13 before returning to the absorption tower 1 to continue absorbing hydrogen sulfide in the raw acid gas;

[0051] (4) After the acid gas described in step (2) is cooled to 35° C. by the acid gas air cooler 7 and the acid gas aftercooler 8, the concentrated acid gas with high hydrogen sulfide concentration and condensed water enter the regeneration tower reflux tank 9. After separation, the acid gas is discharged from the top of the regeneration tower reflux tank 9, and the condensed water is pressurized by the regeneration tower reflux pump 10 from the bottom of the regeneration tower reflux tank 9 and returned to the regeneration tower 6 as reflux liquid;

[0052] (5) When the super-concentration line is not turned on, all the acid gas (hydrogen sulfide concentration ≥ 50 mol%) discharged in step (4) enters the main combustion furnace 15 of the sulfur recovery unit; when the super-concentration line is turned on, most of the acid gas (hydrogen sulfide concentration ≥ 60 mol%) discharged in step (4) enters the main combustion furnace 15 of the sulfur recovery unit, and at the same time, a small portion of the acid gas (10 mol%-20 mol%) is used as concentrated gas and returned to the absorption tower 1 through the super-concentration line;

[0053] (6) The acid gas entering the sulfur recovery unit in step (5) is mixed with a specific proportion of air and burned in the main combustion furnace 15, and a Claus reaction occurs, whereby most of the hydrogen sulfide is converted into elemental sulfur and discharged from the rear of the main combustion furnace 15 along with the process gas;

[0054] (7) After the process gas in step (6) is cooled by the waste heat boiler 16 and the primary sulfur condenser 17, the condensed liquid sulfur is discharged from the bottom of the primary sulfur condenser 17, and the process gas is discharged from the top of the primary sulfur condenser 17;

[0055] (8) The process gas discharged from the upper portion of the primary sulfur condenser 17 in step (7) is heated in the primary reheat furnace 18 and then enters the primary Claus reactor 19 to continue the reaction. The remaining hydrogen sulfide and sulfur dioxide in the process gas are further converted into elemental sulfur under the action of the catalyst. The resulting elemental sulfur-containing process gas is discharged from the lower portion of the primary Claus reactor 19.

[0056] (9) The process gas discharged from the lower portion of the primary Claus reactor 19 in step (8) is cooled in the secondary sulfur condenser 20, and the condensed liquid sulfur is discharged from the bottom of the secondary sulfur condenser 20, and the process gas is discharged from the upper portion of the secondary sulfur condenser 20;

[0057] (10) The process gas discharged from the upper portion of the secondary sulfur condenser 20 in step (9) is heated in the secondary reheat furnace 21 and then enters the secondary Claus reactor 22 for further reaction. The remaining hydrogen sulfide and sulfur dioxide in the process gas are further converted into elemental sulfur under the action of the catalyst. The resulting elemental sulfur-containing process gas is discharged from the lower portion of the secondary Claus reactor 22.

[0058] (11) The process gas discharged from the lower part of the secondary Claus reactor 22 in step (10) is cooled by the tertiary sulfur condenser 23, and the condensed liquid sulfur is discharged from the bottom of the tertiary sulfur condenser 23, and the tail gas containing a small amount of sulfur dioxide and hydrogen sulfide is discharged from the upper part of the tertiary sulfur condenser 23 and enters the tail gas treatment unit;

[0059] (12) The tail gas from step (11) enters the online combustion furnace 24, is mixed with the combustion gas containing reducing gas generated by the sub-equivalent combustion of the fuel gas, and is heated to 280°C. The generated process gas is discharged from the rear of the online combustion furnace 24;

[0060] (13) The process gas discharged from the rear of the online combustion furnace 24 in step (12) enters the top of the hydrogenation reactor 25. Under the action of the catalyst, the sulfur dioxide in the process gas is completely converted into hydrogen sulfide and discharged from the bottom of the hydrogenation reactor 25.

[0061] (14) The process gas discharged from the bottom of the hydrogenation reactor 25 in step (13) is cooled to 35° C. through the waste heat boiler 26 and the quenching tower 27, and the process gas with condensed water separated is discharged from the top of the quenching tower 27;

[0062] (15) The process gas discharged from the top of the quench tower 27 in step (14) enters the lower middle portion of the absorption tower 1, mixes with the raw acid gas entering from the bottom of the absorption tower 1 in step (1), and together contacts the lean liquid in countercurrent to absorb hydrogen sulfide, and finally the tail gas after absorption is discharged from the top of the absorption tower 1;

[0063] (16) The tail gas containing organic sulfur and trace amounts of hydrogen sulfide after absorption in step (1) and step (15) enters the tail gas incinerator 2, where the temperature is raised to 760°C. At the same time, the organic sulfur and hydrogen sulfide are all converted into sulfur dioxide. The generated flue gas enters the flue gas waste heat boiler 3 connected to the rear of the tail gas incinerator 2, and after cooling to 300°C, the flue gas enters the alkali washing unit;

[0064] (17) The flue gas cooled to 300°C in step (16) enters the flue gas heat exchanger 28 and is cooled to 175°C. It then enters the alkali scrubber 29 and is countercurrently contacted with the desulfurization liquid entering from the spray section and the upper part of the packing section of the alkali scrubber. The sulfur dioxide in the flue gas is rapidly absorbed by the desulfurization liquid to generate a sodium sulfite solution. The purified flue gas generated is discharged from the top of the alkali scrubber 29 and enters the purified flue gas separator 31 to separate the carried liquid. After being heated to 180°C in the flue gas heat exchanger 28, the flue gas is discharged into the atmosphere through the chimney 32. At this time, the sulfur dioxide content in the flue gas can be reduced to 50 mg / Nm 3 The following can meet the current stringent environmental protection standards. The desulfurization liquid produced is discharged from the bottom of the alkali washing tower 29;

[0065] (18) The desulfurization liquid discharged from the bottom of the alkali washing tower 29 in step (17) passes through the desulfurization liquid circulation pump 30, with a portion discharged as saline wastewater, a portion entering the packing section of the alkali washing tower 29 as circulating liquid, and a portion entering the spray section of the alkali washing tower 29 as circulating liquid.

[0066] The present invention requires injecting a certain concentration of sodium hydroxide solution from the bottom of the alkali scrubber 29 to control the pH of the circulating liquid at the bottom of the tower between 6.2 and 8.2 to ensure the reaction efficiency of the desulfurization liquid and sulfur dioxide, thereby ensuring the absorption effect of the desulfurization liquid. The present invention requires continuously injecting a certain amount of water into the top of the alkali scrubber to ensure the tower liquid level and maintain the salt concentration in the desulfurization liquid. The present invention also requires injecting air into the bottom of the alkali scrubber 29 to oxidize the sodium sulfite solution generated by the reaction of sulfur dioxide and sodium hydroxide into sodium sulfate, ensuring that the COD value of the wastewater is not too high.

[0067] Traditional Claus sulfur recovery units often control the air distribution in the main combustion furnace to combust one-third of the hydrogen sulfide in the raw acid gas, thereby achieving the optimal chemical ratio of the Claus reactants (i.e., hydrogen sulfide / sulfur dioxide = 2 / 1). However, when processing low-concentration hydrogen sulfide acid gas, this approach fails to maintain the temperature for stable acid gas flame combustion, resulting in system failure. The principle of the present invention is to utilize the selective absorption properties of amine liquid for hydrogen sulfide. The acid gas is first introduced into the amine liquid absorption tower to increase the hydrogen sulfide concentration in the acid gas, thereby ensuring the smooth operation of the sulfur recovery unit. Simultaneously, after acid gas concentration, the total amount of acid gas is significantly reduced compared to before concentration, which helps to optimize and reduce the equipment and pipeline size of the sulfur recovery unit. Furthermore, the present invention combines the functions of acid gas concentration and sulfur recovery tail gas treatment in the same absorption tower, further simplifying the process flow.

[0068] For acid gas with low hydrogen sulfide concentration and containing organic sulfur, if only the above-mentioned process of first concentrating and then recovering is used, the organic sulfur in the acid gas cannot be absorbed by the amine solution and can only be converted into sulfur dioxide and discharged into the atmosphere with the tail gas incineration, resulting in problems such as substandard tail gas emissions and environmental pollution. The present invention organically combines the reduction-absorption tail gas treatment process and the alkaline washing tail gas treatment process into an integrated process, utilizing the reaction between sodium hydroxide solution and sulfur dioxide to absorb sulfur dioxide. The reaction formula involved is as follows:

[0069] 2NaOH+SO2→Na2SO3+H2O;

[0070] 2NaOH+CO2→Na2CO3+H2O;

[0071] Na2CO3+SO2→Na2SO3+CO2↑;

[0072] Na2SO3+SO2+H2O→2NaHSO3;

[0073] 2NaHSO3+NaOH→Na2SO3+H2O;

[0074] Na2SO3+1 / 2O2→Na2SO4.

[0075] The alkaline washing method is a rapid and thorough process, and the treated flue gas meets the specific emission limits specified in the "Petroleum Refining Industry Pollutant Emission Standard" (GB13570-2015). First, a recyclable amine solution is used to absorb hydrogen sulfide, which serves as a raw material for sulfur recovery. Organic sulfur in the acid gas is incinerated to sulfur dioxide, which is then treated with an alkaline washing method. This method not only meets environmental protection requirements but also reduces alkaline solution consumption.

[0076] In the traditional reduction absorption process, exhaust emissions often fail to meet standards due to unavoidable conditions such as unstable device operation and non-operation of some equipment during startup and shutdown. However, since the present invention organically combines the alkali washing unit, the load of the alkali washing unit can be temporarily increased during startup and shutdown, and the alkali solution consumption can be increased, so that the exhaust gas discharged into the atmosphere meets the standards at all times, which has better operability and environmental friendliness.

Claims

1. A process system for treating hydrogen sulfide-containing acid gas, comprising a sulfur recovery unit, a tail gas treatment unit with acid gas concentration function, and a flue gas alkali washing unit; The tail gas treatment unit is provided with an online combustion furnace (24), a hydrogenation reactor (25), an absorption tower (1), a lean-rich liquid heat exchanger (5), a regeneration tower (6), and a regeneration tower reflux tank (9). The gas outlet of the sulfur recovery unit is connected to the inlet of the online combustion furnace (24), the outlet of the online combustion furnace (24) is connected to the inlet of the hydrogenation reactor (25), the outlet of the hydrogenation reactor (25) is connected to the middle and lower inlet of the absorption tower (1), the sulfur-containing tail gas enters the tail gas treatment unit through the bottom inlet of the absorption tower (1), the bottom outlet of the absorption tower (1) is connected to the upper inlet of the regeneration tower (6) through the lean-rich liquid heat exchanger (5), the upper outlet of the regeneration tower (6) is respectively connected to the upper inlet of the regeneration tower (6) and the gas inlet of the sulfur recovery unit through the regeneration tower reflux tank (9), the bottom outlet of the regeneration tower (6) is connected to the upper inlet of the absorption tower (1) through the lean-rich liquid heat exchanger (5), and the upper outlet of the absorption tower (1) is connected to the gas inlet of the flue gas alkali washing unit.

2. The process system for treating hydrogen sulfide acid gas according to claim 1, comprising a sulfur recovery unit, a tail gas treatment unit with acid gas concentration function, and a flue gas alkali washing unit; The sulfur recovery unit is provided with a main combustion furnace (15) and a Claus treatment device, the upper outlet of the regeneration tower (6) is connected to the inlet of the main combustion furnace (15) through the regeneration tower reflux tank (9), the outlet of the main combustion furnace (15) is connected to the Claus treatment device, the gas outlet of the Claus treatment device is connected to the inlet of the online combustion furnace (24) of the tail gas treatment unit, and the Claus treatment device is provided with a sulfur condenser, a reheat furnace, and a Claus reactor; The tail gas treatment unit is provided with an online combustion furnace (24), a hydrogenation reactor (25), an absorption tower (1), a lean-rich liquid heat exchanger (5), a regeneration tower (6), and a regeneration tower reflux tank (9); the gas outlet of the Claus treatment device is connected to the inlet of the online combustion furnace (24); the outlet of the online combustion furnace (24) is connected to the inlet of the hydrogenation reactor (25); the outlet of the hydrogenation reactor (25) is connected to the middle and lower inlet of the absorption tower (1); the sulfur-containing tail gas enters the tail gas through the bottom inlet of the absorption tower (1); The gas treatment unit comprises a bottom outlet of an absorption tower (1) connected to an upper inlet of a regeneration tower (6) through a lean-rich liquid heat exchanger (5), an upper outlet of the regeneration tower (6) connected to an upper inlet of the regeneration tower (6) and an inlet of a main combustion furnace (15) of a sulfur recovery unit through a regeneration tower reflux tank (9), a bottom outlet of the regeneration tower (6) connected to an upper inlet of the absorption tower (1) through a lean-rich liquid heat exchanger (5), and an upper outlet of the absorption tower (1) connected to an inlet of a tail gas incinerator (2) of a flue gas alkali washing unit; The flue gas alkali washing unit is provided with a tail gas incinerator (2), a flue gas heat exchanger (28), an alkali washing tower (29), and a purified flue gas liquid separation tank (31); the upper outlet of the absorption tower (1) is connected to the inlet of the tail gas incinerator (2); the outlet of the tail gas incinerator (2) is connected to the inlet of the alkali washing tower (29) through the flue gas heat exchanger (28); the upper outlet of the alkali washing tower (29) is connected to the flue gas heat exchanger (28) through the purified flue gas liquid separation tank (31); the flue gas heat exchanger (28) leads to the atmosphere; and the liquid outlet of the purified flue gas liquid separation tank (31) is connected to the alkali washing tower (29).

3. The process system for treating hydrogen sulfide acid gas according to claim 2, wherein: In the tail gas treatment unit, a rich liquid pump (4) is provided between the bottom outlet of the absorption tower (1) and the lean-rich liquid heat exchanger (5), an acid gas air cooler (7) and an acid gas aftercooler (8) are provided between the upper outlet of the regeneration tower (6) and the regeneration tower reflux tank (9), a lean liquid pump (11), a lean liquid air cooler (12), and a lean liquid aftercooler (13) are provided between the lean-rich liquid heat exchanger (5) and the upper inlet of the absorption tower (1), a regeneration tower reflux pump (10) is provided between the regeneration tower reflux tank (9) and the upper inlet of the regeneration tower (6); and a regeneration tower reboiler (14) is provided at the lower part of the regeneration tower (6).

4. The process system for treating hydrogen sulfide acid gas according to claim 2, wherein: In the sulfur recovery unit, a waste heat boiler (16) is provided between the outlet of the main combustion furnace (15) and the Claus treatment device. The Claus treatment device comprises a primary sulfur condenser (17), a primary reheat furnace (18), a primary Claus reactor (19), a secondary sulfur condenser (20), a secondary reheat furnace (21), a secondary Claus reactor (22), and a tertiary sulfur condenser (23). The gas outlet of the tertiary sulfur condenser (23) is connected to the inlet of the online combustion furnace (24) of the tail gas treatment unit.

5. The process system for treating hydrogen sulfide acid gas according to claim 2, wherein: A waste heat boiler (26) and a quenching tower (27) are provided between the outlet of the hydrogenation reactor (25) and the lower inlet of the absorption tower (1).

6. The process system for treating hydrogen sulfide acid gas according to claim 2, wherein: A flue gas waste heat boiler (3) is provided between the outlet of the tail gas incinerator (2) and the flue gas heat exchanger (28), the flue gas heat exchanger (28) is connected to a chimney (32), and the bottom outlet of the alkali washing tower (29) is connected to the upper inlet of the alkali washing tower (29) through a desulfurization liquid circulation pump (30).

7. The process system for treating hydrogen sulfide acid gas according to any one of claims 1 to 6, wherein: In the tail gas treatment unit, the acid gas is discharged from the top of the regeneration tower reflux tank (9), part of the acid gas enters the bottom of the absorption tower (1) through the super concentration line, and the remaining acid gas enters the main combustion furnace (15) of the sulfur recovery unit.

8. The process system for treating hydrogen sulfide acid gas according to any one of claims 1 to 6, wherein: The alkali washing tower (29) is provided with a spray section, and a packing section is provided on the upper part of the spray section.

9. A process for desulfurizing sulfur-containing tail gas using the process system for treating hydrogen sulfide acid gas according to any one of claims 1 to 8.

10. The sulfur-containing tail gas desulfurization process according to claim 9, wherein: After the sulfur-containing tail gas is concentrated by the tail gas treatment unit, it enters the sulfur recovery unit, undergoes Claus reaction, and is separated to obtain sulfur and sulfur recovery tail gas. The sulfur recovery tail gas enters the tail gas treatment unit, and is successively burned and hydrogenated, and the obtained gas enters the absorption tower of the tail gas treatment unit; In the tail gas treatment unit, the gas absorbed by the absorption tower enters the flue gas alkali washing unit, is incinerated and alkali washed in sequence, and the desulfurized gas is discharged.

11. The sulfur-containing tail gas desulfurization process according to claim 9, wherein: In the tail gas treatment unit, sulfur-containing tail gas is introduced from the bottom of the absorption tower (1), and is absorbed by the countercurrent absorption liquid to obtain rich liquid. The rich liquid passes through the rich liquid pump (4) and the lean-rich liquid heat exchanger (5) from the bottom of the absorption tower (1) in sequence and enters the regeneration tower (6). The lean liquid obtained after the regeneration treatment passes through the lean-rich liquid heat exchanger (5), the lean liquid pump (11), the lean liquid air cooler (12), and the lean liquid aftercooler (13) from the bottom of the regeneration tower (6) in sequence and enters the top of the absorption tower (1). The acid gas obtained after the regeneration treatment passes through the acid gas air cooler (7) and the acid gas aftercooler (8) from the top of the regeneration tower (6) in sequence and enters the regeneration tower reflux tank (9). The separated condensed water passes through the regeneration tower reflux pump (10) from the bottom of the regeneration tower reflux tank (9) and is pressurized before entering the regeneration tower (6). The acid gas is discharged from the top of the regeneration tower reflux tank (9) and enters the sulfur recovery unit.

12. The sulfur-containing tail gas desulfurization process according to claim 9, wherein: In the sulfur recovery unit, the acid gas discharged from the tail gas treatment unit enters the main combustion furnace (15) to undergo Claus reaction to generate process gas containing elemental sulfur. The process gas containing elemental sulfur is discharged from the main combustion furnace (15), passes through a waste heat boiler (16) and a primary sulfur condenser (17), is cooled to obtain liquid sulfur, and is discharged from the bottom of the primary sulfur condenser (17). The remaining process gas is discharged from the upper part of the primary sulfur condenser (17) and then enters a primary reheat furnace (18) and a primary Claus reactor (19) in sequence to generate process gas containing elemental sulfur. The process gas containing elemental sulfur is discharged from the primary Claus reactor. The sulfur is discharged from the lower part of the reactor (19) and enters the secondary sulfur condenser (20). Liquid sulfur is discharged from the bottom of the secondary sulfur condenser (20) after being cooled. The remaining process gas enters the secondary reheat furnace (21) and the secondary Claus reactor (22) from the upper part of the secondary sulfur condenser (20) to generate a process gas containing elemental sulfur. The process gas containing elemental sulfur is discharged from the lower part of the secondary Claus reactor (22) and enters the tertiary sulfur condenser (23). Liquid sulfur is discharged from the bottom of the tertiary sulfur condenser (23) after being cooled. The remaining tail gas is discharged from the upper part of the tertiary sulfur condenser (23) and enters the tail gas treatment unit.

13. The sulfur-containing tail gas desulfurization process according to claim 9, wherein: In the tail gas treatment unit, the tail gas discharged from the sulfur recovery unit enters the online combustion furnace (24) for combustion, enters the hydrogenation reactor (25) for hydrogenation reaction, passes through the waste heat boiler (26) and the quenching tower (27), and is finally discharged from the top of the quenching tower (27) and enters the middle and lower part of the absorption tower (1).

14. The sulfur-containing tail gas desulfurization process according to claim 9, wherein: In the flue gas alkali washing unit, the gas absorbed by the absorption tower enters the tail gas incinerator (2) from the top of the absorption tower (1) to generate flue gas, and the flue gas enters the flue gas waste heat boiler (3), the flue gas heat exchanger (28), and the alkali washing tower (29) in sequence. The flue gas after alkali washing is discharged from the top of the alkali washing tower (29), enters the purified flue gas liquid separator (31) and the flue gas heat exchanger (28) in sequence, and is finally discharged through the chimney (32). The desulfurization liquid is discharged from the bottom of the alkali washing tower (29) and enters the alkali washing tower (29) through the desulfurization liquid circulation pump (30) or is discharged as waste liquid.

15. The sulfur-containing tail gas desulfurization process according to claim 14, wherein: The pH of the bottom circulating liquid at the bottom of the alkali washing tower (29) is 6.2-8.

2.

16. The desulfurization process of sulfur-containing tail gas according to claim 9, wherein: The content of hydrogen sulfide in the sulfur-containing tail gas is ≤15 mol%.

17. The desulfurization process of sulfur-containing tail gas according to claim 9, wherein: The hydrogen sulfide concentration of the acid gas entering the sulfur recovery unit is ≥50 mol%.

18. The desulfurization process of sulfur-containing tail gas according to claim 9, wherein: The sulfur dioxide content in the flue gas finally discharged by the desulfurization method of sulfur-containing tail gas is ≤50mg / Nm 3 .

19. The desulfurization process of sulfur-containing tail gas according to claim 9, wherein: The amine liquid used in the absorption tower in the tail gas treatment unit comprises, by weight, 97 parts of MDEA, 1-2 parts of phosphoric acid, 0.5-1 parts of corrosion inhibitor, 0.5-1 parts of defoaming agent, and water.

20. The desulfurization process of sulfur-containing tail gas according to claim 19, wherein: The mass concentration of the amine solution is 40-45%.

21. The desulfurization process of sulfur-containing tail gas according to claim 19, wherein: The corrosion inhibitor comprises one or a combination of two or more of imidazolyl dithiourea, 2-amino-imidazolidinone, di(propynyloxymethyl)isopropylbenzyl ammonium chloride and di(propynyloxymethyl)butylbenzyl ammonium chloride.

22. The desulfurization process of sulfur-containing tail gas according to claim 19, wherein: The defoaming agent includes polyether modified silicone oil.

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