A method and system for controlled corrosion purification plant claus tail gas treatment

Abstract

The application discloses a kind of corrosion controllable purification plant Claus tail gas treatment method and system, it is related to Claus tail gas treatment technical field.A kind of corrosion controllable purification plant Claus tail gas treatment method, comprising the following steps: Claus tail gas is incinerated, sulfur compound is converted into sulfur dioxide, obtains high-temperature flue gas;High-temperature flue gas is cooled after heat exchange;The flue gas after cooling is treated by washing;Washed flue gas is treated by organic amine absorption, organic amine absorption tail gas is incinerated;Organic amine liquid of absorption tail gas is treated after regeneration, separated gas is treated by sulfur recovery, sulfur-containing gas is converted into sulfur.The application can reduce the temperature of tail gas before washing by increasing heat exchange treatment before washing, avoid SO2 in high-temperature tail gas contact with cooling water to form high-temperature dilute acid, can reduce the corrosion of washing tower, reduce the desalination load of rear-end cooling water.

Description

Technical Field

[0001] This invention relates to the field of Claus exhaust gas treatment technology, specifically to a method and system for treating Claus exhaust gas in a purification plant with controllable corrosion. Background Technology

[0002] Currently, the development and production of sulfur-containing natural gas worldwide relies on natural gas purification processes, with sulfur recovery units being a crucial component. The most widely used sulfur recovery technology in recent decades is the Claus process, which utilizes the reaction of H2S and O2 to produce elemental sulfur. However, this process still generates tail gas containing acidic hazardous gases such as SO2, H2S, and other forms of sulfur, typically requiring further treatment to meet emission standards.

[0003] Existing large-scale natural gas purification plant tail gas treatment processes mainly include reduction absorption and oxidation absorption processes. The reduction absorption process involves hydrogenating the tail gas to convert various forms of sulfides into H2S, followed by desulfurization with an alcohol amine solvent. The subsequent process is similar to the amine desulfurization of the feed gas. The SCOT process is a typical example, with over 200 installations worldwide. This process has a high sulfur recovery rate, but it is now insufficient to meet increasingly stringent SO2 emission requirements. Unlike reduction absorption, oxidation absorption involves high-temperature combustion of the tail gas to convert various forms of sulfides into SO2, followed by treatment with organic amines. The Canslov process is a typical example, but its application in the global natural gas purification field is still very limited. Due to its high processing efficiency and excellent SO2 concentration control, especially after the release of the "Emission Standard of Air Pollutants for Onshore Oil and Gas Extraction Industry" (GB39728-2020), it has become almost the only choice for tail gas treatment of large-scale sulfur-containing natural gas purification units. China National Petroleum Corporation Southwest Oil and Gas Field Company is the first unit to apply this technology.

[0004] The oxidation absorption process boasts superior performance in terms of exhaust gas treatment capacity and SO2 emission standards. However, it faces severe corrosion problems during actual operation, particularly on the Venturi tower walls. This is due to the following reasons:

[0005] 1. When the high-temperature flue gas (295℃) comes into contact with the cooling water, it forms a high-temperature dilute acid. Since the cooling water is typically recycled, over time, SO2 continuously dissolves to form H2SO3 and is oxidized to form H2SO4. This results in a persistently low pH value in the cooling water, even after the addition of alkaline substances (sodium hydroxide, sodium carbonate, etc.). Forcibly adjusting the pH value would consume a large amount of alkali and cause the mineralization of the cooling water to continuously increase, leading to a rise in the desalination load on the downstream cooling water system. Actual operation monitoring results show that the cooling water pH is consistently ≤2, indicating significant signs of high-temperature acid corrosion.

[0006] 2. The flue gas enters the Venturi tower (scrubber) at a velocity as high as 10 m / s, and cooling water enters the Venturi tower via hydraulic jet. Through intense gas-liquid mass transfer interaction, the two achieve the purpose of scrubbing and cooling. However, this increases the corrosion effect, leading to obvious signs of erosion corrosion on the Venturi tower.

[0007] In the prior art, for example, Chinese patent CN109351126A discloses a method for treating sulfur-containing waste gas. Flue gas at 160-300℃ discharged from a waste heat boiler is sent to a cooling and scrubbing tower via a flue for rapid cooling and scrubbing, and then enters the absorption tower from the bottom after passing through a wet electrostatic precipitator. Chinese patent CN 115448258A discloses a Claus tail gas sulfur recovery system and process, in which the 300-400℃ tail gas generated in the incinerator directly enters the rapid cooling tower for scrubbing. Chinese patent CN108176194A discloses a treatment device and method for tail gas containing sulfur elements and compounds. After the incinerator flue gas is cooled to 300℃ by a waste heat boiler, it enters the rapid cooling tower for further cooling after passing through a tail gas-flue gas heat exchanger. Chinese patent CN108686490B discloses a flue gas desulfurization and dust removal tower and method. The rapid cooling spray zone uses large-diameter atomizing nozzles to intercept and rapidly cool the flue gas, removing dust and sulfur dioxide. The operating temperature is 60-300℃, and an alkaline solution is used as the circulating coolant, controlling the pH between 6 and 11. While the above technologies treat exhaust gas, they do not consider the corrosion caused by cooling high-temperature flue gas. Therefore, there is an urgent need for a method to treat Claus exhaust gas and achieve corrosion control. Summary of the Invention

[0008] The technical problem to be solved by the present invention is that the existing technology causes serious corrosion problems when treating Claus exhaust gas, which affects the long-term use of the equipment and increases maintenance costs. The purpose is to provide a method and system for treating Claus exhaust gas in a purification plant with controllable corrosion, thereby solving the problem of equipment corrosion.

[0009] This invention is achieved through the following technical solution:

[0010] A method for treating Claus exhaust gas from a purification plant with controllable corrosion includes the following steps:

[0011] The Claus exhaust gas is incinerated to convert sulfur compounds into sulfur dioxide, resulting in high-temperature flue gas.

[0012] High-temperature flue gas is cooled down through heat exchange;

[0013] The cooled flue gas is then treated with a washing process.

[0014] After being washed, the flue gas is treated by organic amine absorption. The exhaust gas after organic amine absorption is heated by heat exchange and then discharged into the atmosphere through a chimney.

[0015] After the organic amine liquid that absorbs the tail gas is regenerated, the separated gas undergoes sulfur recovery treatment to convert the sulfur-containing gas into sulfur.

[0016] After heat exchange, the high-temperature flue gas is cooled to 160-200℃;

[0017] The flue gas is cooled to 60-90℃ after scrubbing treatment.

[0018] As one possible design, the above-mentioned washing process is carried out using a washing liquid comprising water and a corrosion inhibitor.

[0019] As one possible design, the water mentioned above is specifically softened water.

[0020] As one possible design, the concentration of the corrosion inhibitor is 10 to 200 ppm.

[0021] As one possible design, the aforementioned corrosion inhibitor is a water-soluble sulfonated polymer compound.

[0022] As one possible design, the aforementioned heat exchange includes heat exchange and / or waste heat recovery.

[0023] Secondly, the present invention provides a corrosion-controlled Krauss exhaust gas treatment system for purification plants, comprising:

[0024] A combustion furnace is used to burn Claus exhaust gas, converting sulfides into sulfur dioxide;

[0025] Heat exchanger, connected to the heat exchanger, to exchange heat and cool down the high-temperature flue gas after combustion;

[0026] A scrubbing tower, connected to the heat exchanger, is used to scrub and then cool the cooled flue gas.

[0027] The absorption tower is connected to the scrubbing tower and the heat exchanger respectively, and is used to absorb sulfur dioxide in the cooled flue gas and to send the absorbed tail gas to the heat exchanger for heat exchange.

[0028] A regeneration tower, connected to the absorption tower, is used to regenerate the absorbent liquid after absorbing sulfur dioxide.

[0029] As one possible design, both the input and output ends of the aforementioned scrubbing tower are connected to a heat exchanger.

[0030] As one possible design, the aforementioned regeneration tower is connected to a reboiler.

[0031] As one possible design, the aforementioned scrubbing tower is made of high-grade acid-resistant alloys, such as super austenitic stainless steel or nickel-based alloys.

[0032] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0033] This invention reduces the temperature of the exhaust gas by adding heat exchange treatment before washing, preventing the formation of high-temperature dilute acid from SO2 in the exhaust gas contacting the cooling water. This significantly alleviates the corrosion of the scrubbing tower by the flue gas. Furthermore, reducing SO2 dissolution in the cooling water lowers the water's salinity and reduces the desalination load on the downstream cooling water. In addition, this invention employs organic amine absorption and regeneration, while strictly controlling the temperature in each process stage. This balances the corrosion control of the flue gas with the consumption of inorganic alkali at an acceptable level, avoiding the excessive use of inorganic alkali and reducing wastewater treatment volume and inorganic solid waste generation, resulting in significant environmental benefits.

[0034] The exhaust gas treatment system provided by this invention selects a nickel-based alloy resistant to sulfuric acid corrosion in the scrubbing tower. Even if the flue gas enters the scrubbing tower at high speed and the cooling water enters the scrubbing tower in a spray manner, the contact between the two will not cause serious corrosion to the scrubbing tower, which can greatly extend the service life of the equipment. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0036] Figure 1 This is a schematic diagram of the connection structure of a corrosion-controllable Krauss tail gas treatment system for a purification plant according to the present invention.

[0037] Figure 2 This is a graph showing the corrosion rate of S31254 at different temperatures as a function of sulfuric acid concentration, according to the present invention.

[0038] Figure 3 The graph shows the effect of temperature and pH value on the S31254 austenitic super stainless steel of the present invention.

[0039] Figure 4 This is a comparison chart of the corrosion rates of four metal materials at 160°C, as presented in this invention.

[0040] The attached diagram shows the markings and corresponding component names:

[0041] 1-Combustion furnace; 2-Heat exchanger; 3-Scrubbing tower; 4-Absorption tower; 5-Regeneration tower; 6-Cooling equipment; 7-Reboiler. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for explanation only and are not intended to limit the invention. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0043] While existing technologies treat exhaust gases, none of them take into account the corrosion caused by the cooling of high-temperature flue gas. Therefore, there is an urgent need to provide a method and system for treating Claus exhaust gases and achieving corrosion control.

[0044] In a first aspect, the present invention provides a method for treating Claus exhaust gas from a purification plant with controllable corrosion, comprising the following steps:

[0045] S1. The Claus exhaust gas is incinerated to convert sulfur-containing compounds into sulfur dioxide, resulting in high-temperature flue gas.

[0046] Incineration can oxidize unreacted H2S and some sulfides into SO2, which, together with the original SO2, forms even more SO2.

[0047] S2. The high-temperature flue gas is cooled down through heat exchange.

[0048] Through heat exchange, the high-temperature flue gas is cooled from about 800°C to below 200°C. As the inventors have discovered, the higher the temperature, the more difficult it is to control corrosion. Lowering the temperature to below 200°C can reduce corrosion.

[0049] In some embodiments of the present invention, the high-temperature flue gas is cooled to 160–200°C after heat exchange. The flue gas can be 165°C, 175°C, 180°C, 185°C, or any other temperature value within the range of 160–200°C.

[0050] After research, the inventors discovered that when the flue gas temperature is below 160°C, SO2 will condense and eventually form H2SO4, which will cause equipment to be corroded, i.e., acid dew point corrosion.

[0051] Preferably, the high-temperature flue gas is cooled to 170–190°C.

[0052] Preferably, the heat exchange includes heat exchange and / or waste heat recovery.

[0053] S3. The cooled flue gas is then treated by washing.

[0054] The gas is thoroughly mixed with the flue gas scrubbing liquid inside the tower, cooling it to approximately 75°C to meet the requirements for entering the downstream amine absorption tower. It should be noted that the scrubbing tower's function is to remove particulate impurities from the flue gas and to cool it. Due to the pre-heat exchange treatment, the flue gas temperature decreases, reducing its solubility in the cooling water. This prevents the absorption of most acidic gases, slows down the rate of pH decrease in the cooling water, reduces the increased consumption of inorganic alkali for pH adjustment, and improves the subsequent sulfur yield.

[0055] In some embodiments of the present invention, the flue gas is cooled to 60-90°C after the above-mentioned flue gas scrubbing treatment.

[0056] Preferably, the flue gas is cooled to 60–80°C after the above-mentioned scrubbing treatment. More preferably, it is 60–70°C, and more preferably 70°C.

[0057] In some embodiments of the present invention, the above-mentioned washing treatment is carried out by a washing liquid, which includes water and a corrosion inhibitor.

[0058] Preferably, the sulfate ion concentration is monitored during the recycling of the washing liquid. When the sulfate ion concentration is high (>500 mg / L), it is removed by means of ion exchange resin or membrane separation. Since sulfate is inevitably generated and is a strong acid in the presence of hydrogen ions, this treatment can slow down the rate at which the pH value of the washing liquid decreases, thereby protecting the washing tower.

[0059] In some embodiments of the present invention, the water described above is specifically softened water.

[0060] In some embodiments of the present invention, the concentration of the corrosion inhibitor is 10 to 200 ppm. Preferably, it is 50 to 200 ppm.

[0061] In some embodiments of the present invention, the corrosion inhibitor is a water-soluble sulfonated polymer compound.

[0062] Preferably, the sulfonated polymer compound is a sulfonated polymer with a molecular weight of 10,000-50,000, a degree of sulfonation greater than 70%, and high temperature resistance, such as sulfonated polycarbonate and sulfonated polystyrene.

[0063] S4. The flue gas after washing is treated by organic amine absorption. The exhaust gas after organic amine absorption is heated by heat exchange and then discharged into the atmosphere through a chimney.

[0064] S5. After the organic amine liquid that absorbs the tail gas is regenerated, the separated gas undergoes sulfur recovery treatment to convert the sulfur-containing gas into sulfur.

[0065] Secondly, the present invention provides a Krauss exhaust gas treatment system for a purification plant with controllable corrosion, referring to... Figure 1 ,include

[0066] Combustion furnace 1 is used to burn Claus exhaust gas and then send the combusted exhaust gas to heat exchanger 2 for heat exchange.

[0067] Heat exchanger 2, connected to heat exchanger 2, cools down the high-temperature flue gas after combustion, and can utilize the high-temperature heat as waste heat to improve energy efficiency.

[0068] The gas inlet of the scrubbing tower 3 is connected to the heat exchanger 2. It is used to scrub the cooled flue gas and then cool it down again. The scrubbed flue gas is sent from the gas outlet to the absorption tower 4 for treatment.

[0069] Absorption tower 4 is connected to the scrubbing tower 3 and the heat exchanger 2 respectively. It is used to absorb hydrogen sulfide in the cooled flue gas through organic amine and to send the absorbed tail gas to the heat exchanger 2 for heat exchange. Its organic amine output end is connected to the regeneration tower 5 for regenerating the amine liquid.

[0070] The regeneration tower 5 is connected to the absorption tower 4 and is used to regenerate the absorbent after absorbing hydrogen sulfide, and to return the regenerated absorbent to the absorption tower for reuse.

[0071] In some embodiments of the present invention, the input end and the output end of the washing tower 3 are both connected to the heat exchanger 6. The heat exchanger is used to cool down the used coolant and remove sulfate ions before returning it to the washing tower 3 for reuse.

[0072] In some embodiments of the present invention, the regeneration tower 5 is connected to a reboiler 7 for heating the organic amine, releasing the absorbed hydrogen sulfide and sulfur dioxide, forming a sulfide-rich gas, and restoring the absorption capacity of the amine solution.

[0073] In some embodiments of the present invention, the material of the washing tower 3 is a high-grade acid-resistant alloy.

[0074] Preferably, the washing tower material includes, but is not limited to, Inconel 625, nickel-based C276 Hastelloy, nickel-based C22 Hastelloy, Hastelloy G3, chromium-nickel-iron alloy 625, and chromium-nickel-iron alloy 825.

[0075] Example 1

[0076] A method for treating Claus exhaust gas from a purification plant with controllable corrosion includes the following steps:

[0077] S1. The Claus exhaust gas is incinerated to convert sulfur-containing compounds into sulfur dioxide, resulting in high-temperature flue gas at around 800°C.

[0078] S2. The high-temperature flue gas is cooled to 200°C through heat exchange (heat exchange and / or waste heat recovery);

[0079] S3. The cooled flue gas is washed with a washing solution (an aqueous solution with a corrosion inhibitor concentration of 10 ppm) to cool it down to 80°C.

[0080] S4. The flue gas after washing is treated by organic amine absorption. The exhaust gas after organic amine absorption is heated by heat exchange and then discharged into the atmosphere through the chimney.

[0081] S5. After the organic amine liquid that absorbs the tail gas is regenerated, the separated gas undergoes sulfur recovery treatment to convert the sulfur-containing gas into sulfur.

[0082] In this embodiment, the material of the washing tower 3 is chromium-nickel-iron alloy 825.

[0083] Example 2

[0084] A method for treating Claus exhaust gas from a purification plant with controllable corrosion includes the following steps:

[0085] S1. The Claus exhaust gas is incinerated to convert sulfur-containing compounds into sulfur dioxide, resulting in high-temperature flue gas at around 800°C.

[0086] S2. The high-temperature flue gas is cooled to 180°C through heat exchange (heat exchange and / or waste heat recovery);

[0087] S3. The cooled flue gas is washed with a washing solution (an aqueous solution with a corrosion inhibitor concentration of 100 ppm) to cool it down to 70°C.

[0088] S4. The flue gas after washing is treated by organic amine absorption, and the tail gas after organic amine absorption is incinerated.

[0089] S5. After the organic amine liquid that absorbs the tail gas is regenerated, the separated gas undergoes sulfur recovery treatment to convert the sulfur-containing gas into sulfur.

[0090] In this embodiment, the material of the washing tower 3 is chromium-nickel-iron alloy 825.

[0091] Example 3

[0092] A method for treating Claus exhaust gas from a purification plant with controllable corrosion includes the following steps:

[0093] S1. The Claus exhaust gas is incinerated to convert sulfur-containing compounds into sulfur dioxide, resulting in high-temperature flue gas at around 800°C.

[0094] S2. The high-temperature flue gas is cooled to 170°C through heat exchange (heat exchange and / or waste heat recovery);

[0095] S3. The cooled flue gas is washed with a washing solution (an aqueous solution with a corrosion inhibitor concentration of 150 ppm) to cool it down to 60°C.

[0096] S4. The flue gas after washing is treated by organic amine absorption, and the tail gas after organic amine absorption is incinerated.

[0097] S5. After the organic amine liquid that absorbs the tail gas is regenerated, the separated gas undergoes sulfur recovery treatment to convert the sulfur-containing gas into sulfur.

[0098] In this embodiment, the material of the washing tower 3 is chromium-nickel-iron alloy 825.

[0099] Example 4

[0100] A method for treating Claus exhaust gas from a purification plant with controllable corrosion includes the following steps:

[0101] S1. The Claus exhaust gas is incinerated to convert sulfur-containing compounds into sulfur dioxide, resulting in high-temperature flue gas at around 800°C.

[0102] S2. The high-temperature flue gas is cooled to 160°C through heat exchange (heat exchange and / or waste heat recovery);

[0103] S3. The cooled flue gas is washed with a washing solution (an aqueous solution with a corrosion inhibitor concentration of 200 ppm) to cool it down to 90°C.

[0104] S4. The flue gas after washing is treated by organic amine absorption, and the tail gas after organic amine absorption is incinerated.

[0105] S5. After the organic amine liquid that absorbs the tail gas is regenerated, the separated gas undergoes sulfur recovery treatment to convert the sulfur-containing gas into sulfur.

[0106] In this embodiment, the material of the washing tower 3 is chromium-nickel-iron alloy 825.

[0107] Example 5

[0108] This embodiment is basically the same as Embodiment 1, except that: the corrosion inhibitor concentration in step S3 is an aqueous solution of 50 ppm, and the gas is cooled to 60°C after washing.

[0109] Example 6

[0110] This embodiment is basically the same as Embodiment 1, except that: the corrosion inhibitor concentration in step S3 is an aqueous solution of 50 ppm, and the gas is cooled to 70°C after washing.

[0111] Example 7

[0112] This embodiment is basically the same as Embodiment 1, except that: in step S3, the corrosion inhibitor concentration is an aqueous solution of 50 ppm, and the gas is cooled to 80°C after washing.

[0113] Example 8

[0114] This embodiment is basically the same as Embodiment 1, except that: the corrosion inhibitor concentration in step S3 is an aqueous solution of 50 ppm, and the gas is cooled to 90°C after washing.

[0115] Example 9

[0116] This embodiment is basically the same as Embodiment 1, except that the material of the washing tower is Hastelloy G3.

[0117] Example 10

[0118] This embodiment is basically the same as Embodiment 1, except that the material of the washing tower is chromium-nickel-iron alloy 625.

[0119] Comparative Example 1

[0120] This comparative example is basically the same as Example 1, except that: the corrosion inhibitor concentration in step S3 is an aqueous solution of 50 ppm, and the gas is cooled to 120°C after washing.

[0121] Comparative Example 2

[0122] This comparative example is basically the same as Example 1, except that: in step S3, the corrosion inhibitor concentration is 50 ppm aqueous solution, and the gas is cooled to 150°C after washing.

[0123] Comparative Example 3

[0124] This comparative example is basically the same as Example 1, except that the material of the washing tower is S31254.

[0125] Experimental Example

[0126] (I) Metal test pieces measuring 30*15*3mm were suspended in the washing towers used in Examples 5-7 and Comparative Examples 1-2, respectively. Following the standard JB / T 7901-2023, "Metallic Materials Laboratory Uniform Corrosion Full Immersion Test Method," the samples were immersed in a simulated washing solution for 3 days. The corrosion rate was calculated based on the weight loss of the test pieces. The corrosion status was confirmed, and the results are as follows: Figure 2 As shown. Observation Figure 2 It can be seen that compared with treatment at 120℃ and 150℃, the corrosion of the metal sheets is significantly reduced when the temperature is lowered to 60-90℃ after flue gas scrubbing, and the corrosion effect is minimal when the temperature is lowered to 70℃. Furthermore, it can be observed that the higher the acid concentration, the more severe the corrosion.

[0127] (II) A 30*15*3mm metal test piece was suspended inside the washing tower of Example 5. Following the standard JB / T 7901-2023, "Metallic Materials Laboratory Uniform Corrosion Full Immersion Test Method," corrosion tests were conducted at 140℃, 160℃, 180℃, 200℃, and 220℃ under different pH conditions. After 3 days in the simulated washing solution, the corrosion rate was calculated based on the weight loss of the test piece. The corrosion was confirmed, and the results are as follows: Figure 3 As shown.

[0128] The experimental results reflect the effects of temperature and pH on corrosion and provide the usable operating environment range for the alloy materials. Comparisons of different alloy materials further illustrate the necessity of material selection. Overall, these results demonstrate that controlling parameters such as temperature and pH, as well as material selection, play an indispensable role in corrosion control of the entire process system.

[0129] (III) Metal test pieces (30*15*3mm) were suspended inside the washing towers of Examples 1, 9-10, and Comparative Example 3, respectively. Corrosion was tested under different pH conditions according to standard JB / T 7901-2023, "Metallic Materials Laboratory Uniform Corrosion Full Immersion Test Method." The test was conducted after 3 days in the simulated washing solution, and the corrosion rate was calculated based on the weight loss of the test pieces. The corrosion was confirmed, and the results are as follows: Figure 4 As shown.

[0130] observe Figure 4 It can be seen that the corrosion performance of scrubbing towers using Hastelloy G3, CrNiFe625, and CrNiFe825 is better than that using S31254. This indicates that selecting these alloys can significantly reduce corrosion and extend the service life of the scrubbing tower.

[0131] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for treating Claus exhaust gas in a purification plant with controllable corrosion, characterized in that, Includes the following steps: The Claus exhaust gas is incinerated to convert sulfur compounds into sulfur dioxide, resulting in high-temperature flue gas. High-temperature flue gas is cooled down through heat exchange; The cooled flue gas is then treated with a washing process. After being washed, the flue gas is treated by organic amine absorption. The exhaust gas after organic amine absorption is heated by heat exchange and then discharged into the atmosphere through a chimney. After the organic amine liquid that absorbs the tail gas is regenerated, the separated gas undergoes sulfur recovery treatment to convert the sulfur-containing gas into sulfur. After heat exchange, the high-temperature flue gas is cooled to 160-200°C. The flue gas is cooled to 60–90°C after scrubbing treatment.

2. The method for treating Claus exhaust gas in a purification plant with controllable corrosion according to claim 1, characterized in that, The washing process is carried out using a washing solution, which includes water and a corrosion inhibitor.

3. The method for treating Claus exhaust gas in a purification plant with controllable corrosion according to claim 2, characterized in that, The water in question is specifically softened water.

4. The method for treating Claus exhaust gas in a purification plant with controllable corrosion according to claim 2, characterized in that, The concentration of the corrosion inhibitor is 10–200 ppm.

5. The method for treating Claus exhaust gas in a purification plant with controllable corrosion according to claim 2, characterized in that, The corrosion inhibitor is a water-soluble sulfonated polymer compound.

6. The method for treating Claus exhaust gas in a purification plant with controllable corrosion according to claim 1, characterized in that, The heat exchange includes heat exchange and / or waste heat recovery.

7. A corrosion-controlled Krauss exhaust gas treatment system for a purification plant, characterized in that, include A combustion furnace is used to burn Claus exhaust gas, converting sulfides into sulfur dioxide; Heat exchanger, connected to the heat exchanger, to exchange heat and cool down the high-temperature flue gas after combustion; A scrubbing tower, connected to the heat exchanger, is used to scrub and then cool the cooled flue gas. The absorption tower is connected to the scrubbing tower and the heat exchanger respectively, and is used to absorb sulfur dioxide in the cooled flue gas and to send the absorbed tail gas to the heat exchanger for heat exchange. A regeneration tower, connected to the absorption tower, is used to regenerate the absorbent liquid after absorbing hydrogen sulfide.

8. The corrosion-controllable Claus exhaust gas treatment system for a purification plant according to claim 7, characterized in that, Both the input and output ends of the washing tower are connected to the heat exchanger.

9. A corrosion-controllable Krauss tail gas treatment system for a purification plant according to claim 7, characterized in that, The regeneration tower is connected to a reboiler.

10. A corrosion-controllable Krauss tail gas treatment system for a purification plant according to claim 7, characterized in that, The washing tower is made of an acid-resistant alloy.

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