Method and apparatus for treating mixed exhaust gas and integrated system

Abstract

The application provides a mixed tail gas treatment method and device. According to an embodiment of the application, the method comprises: reacting mixed tail gas containing SO2 and HCl with a first mixed solution containing chlorosulfonic acid and SO3 to obtain chlorosulfonic acid products and first mixed gas containing SO2 and HCl; reacting the first mixed gas with SO3 gas to obtain second mixed solution containing chlorosulfonic acid and SO3 and second mixed gas containing SO2, HCl and SO3; pickling the second mixed gas to absorb SO3 in the second mixed gas, thereby obtaining third mixed gas containing SO2 and HCl; and washing the third mixed gas to absorb HCl in the third mixed gas, thereby obtaining SO2 gas. According to the method, HCl gas and SO2 gas in the mixed tail gas can be completely separated.

Description

Technical Field

[0001] This invention relates to the field of chemical engineering, and more specifically, to a method, apparatus, and combined system for treating mixed exhaust gases. Background Technology

[0002] In chemical production processes, the treatment and utilization of exhaust gases is a crucial issue for environmental protection and resource recycling. Exhaust gases typically contain various harmful substances, such as hydrogen chloride (HCl) and sulfur dioxide (SO2), which not only cause serious environmental pollution but also pose a threat to human health. Traditional exhaust gas treatment methods are often costly and struggle to achieve effective separation and resource utilization of harmful substances.

[0003] Currently, the most commonly used methods in industrial applications both domestically and internationally are absorption and freezing. Absorption uses water to absorb HCl from a gas mixture. However, since SO2 also has some solubility in water, the hydrochloric acid formed by water absorbing HCl often contains about 1% SO2 by mass, which is highly irritating and cannot be used for subsequent comprehensive utilization. Freezing utilizes the characteristic that SO2 easily condenses at low temperatures to separate the gas mixture after cooling. However, the SO2 condensation temperature is below -10℃, requiring additional refrigeration for separation. Furthermore, single-stage condensation separation is not ideal, necessitating multi-stage separation, resulting in high equipment investment and operating costs.

[0004] Therefore, there is a need to develop a more efficient and environmentally friendly method for treating exhaust gases. Summary of the Invention

[0005] This application aims to address at least one of the technical problems existing in the prior art, to at least some extent.

[0006] In a first aspect, this application provides a method for treating a mixed exhaust gas. According to an embodiment of this application, the method includes: reacting a mixed exhaust gas containing SO2 and HCl with a first mixed liquid containing chlorosulfonic acid and SO3 to obtain a chlorosulfonic acid product and a first mixed gas containing SO2 and HCl; reacting the first mixed gas with SO3 gas to obtain a second mixed liquid containing chlorosulfonic acid and SO3 and a second mixed gas containing SO2, HCl, and SO3; acid washing the second mixed gas to absorb SO3 from the second mixed gas to obtain a third mixed gas containing SO2 and HCl; and washing the third mixed gas with water to absorb HCl from the third mixed gas to obtain SO2 gas.

[0007] According to an embodiment of this application, the first mixture is composed of the second mixture.

[0008] According to embodiments of this application, the method satisfies at least one of the following conditions:

[0009] The chlorosulfonic acid product has a mass concentration of chlorosulfonic acid greater than or equal to 99%;

[0010] The mass concentration of chlorosulfonic acid in the first mixture is 89%-95%;

[0011] The HCl content in the mixed exhaust gas is 30% to 50%.

[0012] According to an embodiment of this application, the reaction of the first mixed gas with SO3 includes: the first mixed gas undergoing a first reaction with SO3 to obtain a third mixed liquid containing chlorosulfonic acid and a fourth mixed gas containing SO2, HCl and SO3; the HCl and SO3 in the fourth mixed gas undergoing a second reaction to obtain a fourth mixed liquid containing chlorosulfonic acid and a second mixed gas; and the fourth mixed liquid and the third mixed liquid are mixed to obtain the second mixed liquid.

[0013] According to an embodiment of this application, the reaction of the first mixed gas with SO3 further includes: causing HCl and SO3 in the fifth mixed gas to undergo a third reaction to obtain a fifth mixed liquid containing chlorosulfonic acid and a sixth mixed gas containing SO2, HCl and SO3; and mixing the fifth mixed liquid, the fourth mixed liquid and the third mixed liquid to obtain the second mixed liquid.

[0014] According to an embodiment of this application, the volume ratio of the first mixed gas to SO3 gas is (1-1.5):1.

[0015] According to embodiments of this application, the method satisfies at least one of the following conditions:

[0016] The temperature of the SO3 gas is 80℃~110℃;

[0017] The purity of the SO3 gas is greater than or equal to 97%.

[0018] According to an embodiment of this application, the pickling is carried out using sulfuric acid with a mass concentration of 95% to 99%.

[0019] According to an embodiment of this application, before the mixed exhaust gas reacts with the first mixture, the method further includes washing and drying the mixed exhaust gas.

[0020] According to an embodiment of this application, the mixed tail gas is washed and dried using sulfuric acid with a mass concentration of 90% to 99%.

[0021] According to embodiments of this application, the method satisfies at least one of the following:

[0022] The temperature at which the mixed exhaust gas reacts with the first mixed liquid is 50°C to 80°C.

[0023] The pressure at which the mixed exhaust gas reacts with the first mixture is 0 bar to 1.5 bar;

[0024] The reaction temperature between the first mixed gas and SO3 gas is 50℃~80℃;

[0025] The pressure at which the first mixed gas reacts with SO3 gas is 0 bar to 1.5 bar.

[0026] A second aspect of this application provides an apparatus for implementing the aforementioned method. According to an embodiment of this application, the apparatus includes: a purification tower for reacting a mixed tail gas containing SO2 and HCl with a first mixed liquid containing chlorosulfonic acid and SO3 to obtain a chlorosulfonic acid product and a first mixed gas containing SO2 and HCl; a synthesis tower, connected to the purification tower, for reacting the first mixed gas with SO3 to obtain a second mixed liquid containing chlorosulfonic acid and a second mixed gas containing SO2, HCl, and SO3; an acid washing tower, connected to the synthesis tower, for acid washing the second mixed gas to obtain a third mixed gas containing SO2 and HCl; a water washing tower, connected to the acid washing tower, for water washing the third mixed gas to obtain SO2 gas; and a finished product tank, connected to the purification tower, for storing the chlorosulfonic acid product.

[0027] According to an embodiment of this application, the synthesis tower includes: a first synthesis tower and a second synthesis tower connected in series, wherein the first synthesis tower is connected to the purification tower and the second synthesis tower is connected to the pickling tower.

[0028] According to an embodiment of this application, the synthesis tower further includes a third synthesis tower connected in series with the first synthesis tower and the second synthesis tower, wherein the first synthesis tower is connected to the purification tower and the third synthesis tower is connected to the pickling tower.

[0029] According to embodiments of this application, the device satisfies at least one of the following conditions:

[0030] The mass concentration of chlorosulfonic acid in the mixture in the first synthesis tower is 89%-95%;

[0031] The mass concentration of chlorosulfonic acid in the mixture in the second synthesis tower is 50%-60%.

[0032] The mass concentration of chlorosulfonic acid in the mixture in the third synthesis tower is 30%-50%.

[0033] According to an embodiment of this application, the apparatus further includes an HCl scrubbing tower, which is connected to the purification tower and is used to scrub and dry the mixed exhaust gas.

[0034] According to an embodiment of this application, the device further includes a gas-liquid separator disposed between the synthesis tower and the acid washing tower, wherein the gas-liquid separator is connected to both the synthesis tower and the acid washing tower, and is used to separate the liquid in the second mixed gas.

[0035] According to an embodiment of this application, the water washing tower includes a first water washing tower and a second water washing tower connected in series.

[0036] A third aspect of this application provides a combined system. According to an embodiment of this application, the combined system includes: a fluoroamine preparation apparatus; the aforementioned mixed tail gas treatment apparatus, connected to the fluoroamine preparation apparatus, for receiving mixed tail gas from the fluoroamine preparation apparatus; and a sulfuric acid preparation apparatus, connected to the mixed tail gas treatment apparatus, for receiving SO2 gas from the mixed tail gas treatment apparatus.

[0037] According to an embodiment of this application, the sulfuric acid preparation apparatus includes a nicotinic acid component, which is connected to the mixed tail gas treatment device and is used to provide SO3 gas to the mixed tail gas treatment device.

[0038] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0039] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0040] Figure 1 This is a flowchart of a method for treating mixed exhaust gases according to an embodiment of this application;

[0041] Figure 2 This is a flowchart of a method for treating mixed exhaust gases according to an embodiment of this application;

[0042] Figure 3 This is a schematic diagram of a mixed exhaust gas treatment device according to an embodiment of this application;

[0043] Figure 4 This is a schematic diagram of a mixed exhaust gas treatment device according to an embodiment of this application;

[0044] Figure 5 This is a schematic diagram of a mixed exhaust gas treatment device according to an embodiment of this application;

[0045] Figure 6 This is a schematic diagram of a mixed exhaust gas treatment device according to an embodiment of this application;

[0046] Figure 7This is a schematic diagram of a mixed exhaust gas treatment device according to an embodiment of this application;

[0047] Figure 8 This is a schematic diagram of a mixed exhaust gas treatment device according to an embodiment of this application;

[0048] Figure 9 This is a schematic diagram of the structure of the joint system according to an embodiment of this application;

[0049] Figure 10 This is a schematic diagram of a mixed exhaust gas treatment device according to an embodiment of this application. Detailed Implementation

[0050] The embodiments of the technical solution of this application are described in detail below. These embodiments are only used to more clearly illustrate the technical solution of this application, and are therefore merely examples and should not be used to limit the scope of protection of this application.

[0051] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0052] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is also expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers, and ranges defined in this way can include endpoints a and b. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0053] In this document, the terms “comprising” or “including” are open-ended expressions, meaning that they include the contents specified in this application but do not exclude other contents.

[0054] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more.

[0055] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0056] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0057] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0058] Treatment methods for mixed exhaust gases

[0059] This application proposes a method for treating mixed exhaust gases. According to an embodiment of this application, refer to... Figure 1 The method includes:

[0060] S100: React the mixed tail gas containing SO2 and HCl with the first mixed liquid containing chlorosulfonic acid and SO3 to obtain chlorosulfonic acid product and the first mixed gas containing SO2 and HCl.

[0061] In this step, the main reaction is that SO3 in the first mixture absorbs HCl in the mixed tail gas to produce chlorosulfonic acid. This allows for a further increase in the concentration of the finished chlorosulfonic acid product, which can then be used or sold directly without further processing.

[0062] In some embodiments of this application, the mass concentration of chlorosulfonic acid in the finished chlorosulfonic acid product is greater than or equal to 99% (specifically, 99%, 99.2%, 99.5%, 99.8%, 100%, etc.).

[0063] In some embodiments of this application, the mass concentration of chlorosulfonic acid in the first mixture is 89%-95% (specifically, 89%, 90%, 91%, 92%, 93%, 94%, 95%, etc.).

[0064] In some embodiments of this application, the HCl content in the mixed exhaust gas is 30% to 50% (specifically, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 46%, 48%, 50%, etc.).

[0065] Therefore, by reacting the first mixture with a high concentration of chlorosulfonic acid with the mixed tail gas with a high concentration of HCl, the small amount of SO3 in the first mixture can still efficiently absorb the HCl in the mixed tail gas, thereby further improving the quality of the chlorosulfonic acid product.

[0066] In some embodiments of this application, the reaction temperature between the mixed exhaust gas and the first mixed liquid is 50°C to 80°C. For example, it can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, or any range of the above values. Within the above temperature range, the reaction rate of HCl gas in the mixed exhaust gas with SO3 in the first mixed liquid to produce chlorosulfonic acid can be accelerated, thereby improving production efficiency.

[0067] In some embodiments of this application, the pressure at which the mixed exhaust gas reacts with the first mixture is 0 bar to 1.5 bar. For example, it can be 0 bar, 0.1 bar, 0.2 bar, 0.3 bar, 0.4 bar, 0.5 bar, 0.6 bar, 0.7 bar, 0.8 bar, 0.9 bar, 1.0 bar, 1.1 bar, 1.2 bar, 1.3 bar, 1.4 bar, 1.5 bar, etc., or any range of the above values. By controlling the pressure within the above range, it helps to increase the rate at which HCl gas in the mixed exhaust gas reacts with SO3 in the first mixture to produce chlorosulfonic acid, thus accelerating the reaction process.

[0068] In some embodiments of this application, in order to increase the contact area between the mixed exhaust gas and the first mixture and improve the reaction efficiency, the mixed exhaust gas can be introduced from the bottom or lower part of the first mixture. In this way, after the mixed exhaust gas is introduced, it gradually diffuses upward from the bottom or lower part of the first mixture, significantly increasing the contact area with the first mixture and significantly improving the reaction efficiency.

[0069] Understandably, to further improve the reaction effect and degree, the temperature of the first mixture can be gradually increased from bottom to top. For example, the temperature at the bottom of the first mixture can be 50°C, and the temperature at the top of the first mixture can be 80°C. Such a temperature setting is more conducive to the reaction of sulfur trioxide in the mixed tail gas and the first mixture, thereby further improving the quality of the chlorosulfonic acid product and the absorption rate of HCl.

[0070] S200: React the first mixed gas with SO3 gas to obtain a second mixed liquid containing chlorosulfonic acid and SO3 and a second mixed gas containing SO2, HCl and SO3.

[0071] In this step, the main reaction is as follows: HCl gas in the first mixed gas reacts with SO3 gas to produce chlorosulfonic acid, specifically, the reaction formula is HCl + SO3 → ClSO3H. Therefore, HCl in the first mixed gas can be effectively absorbed through the above reaction, and commercially valuable chlorosulfonic acid can be obtained, realizing HCl recovery and resource utilization at the same time.

[0072] In some embodiments of this application, the reaction between the first mixed gas and SO3 gas can be carried out in one step or in multiple steps. More reaction steps result in better HCl absorption and a higher chlorosulfonic acid content in the resulting second mixture, but also higher costs; conversely, fewer reaction steps result in relatively poorer HCl absorption and a lower chlorosulfonic acid content in the resulting second mixture, but also lower costs. Considering both HCl absorption and processing costs, the reaction between the first mixed gas and SO3 gas can be carried out in two or three steps.

[0073] According to a specific example of this application, the reaction of the first mixed gas with SO3 gas can be carried out in two steps. Specifically, the reaction of the first mixed gas with SO3 includes: the first mixed gas undergoing a first reaction with SO3 to obtain a third mixed liquid containing chlorosulfonic acid and a fourth mixed gas containing SO2, HCl and SO3; the HCl and SO3 in the fourth mixed gas undergoing a second reaction to obtain a fourth mixed liquid containing chlorosulfonic acid and a fifth mixed gas containing SO2, HCl and SO3; and the fourth mixed liquid and the third mixed liquid are mixed to obtain a second mixed liquid.

[0074] As an example, the above two-step reaction can be carried out in two reaction vessels connected in series (including but not limited to a synthesis tower). Specifically, a first mixed gas and SO3 gas are introduced into the first reaction vessel and reacted in the first reaction vessel to obtain a third mixed liquid and a fourth mixed gas. The fourth mixed gas is introduced into the second reaction vessel through a pipeline and reacted to obtain a fourth mixed liquid and a fifth mixed gas. The fourth mixed liquid can be introduced into the first reaction vessel through a circulation pipeline to mix with the third mixed liquid.

[0075] According to a specific example of this application, the reaction of the first mixed gas with SO3 gas can be carried out in three steps. Specifically, the reaction of the first mixed gas with SO3 includes: the first mixed gas undergoing a first reaction with SO3 to obtain a third mixed liquid containing chlorosulfonic acid and a fourth mixed gas containing SO2, HCl, and SO3; the HCl and SO3 in the fourth mixed gas undergoing a second reaction to obtain a fourth mixed liquid containing chlorosulfonic acid and a fifth mixed gas containing SO2, HCl, and SO3; the HCl and SO3 in the fifth mixed gas undergoing a third reaction to obtain a fifth mixed liquid containing chlorosulfonic acid and a sixth mixed gas containing SO2, HCl, and SO3; and the fifth mixed liquid, the fourth mixed liquid, and the third mixed liquid are mixed to obtain a second mixed liquid.

[0076] As an example, the above three-step reaction can be carried out in three reaction vessels connected in series (including but not limited to a synthesis tower). Specifically, the first mixed gas and SO3 gas are introduced into the first reaction vessel and reacted there to obtain a third mixed liquid and a fourth mixed gas. The fourth mixed gas is introduced into the second reaction vessel through a pipeline and reacted there to obtain a fourth mixed liquid and a fifth mixed gas. The fifth mixed gas is introduced into the third reaction vessel through a connecting pipeline and reacted there to obtain a fifth mixed liquid and a sixth mixed gas. The fifth mixed liquid in the third reaction vessel can be introduced into the second reaction vessel through a circulation pipeline and mixed with the fourth mixed liquid generated in the second reaction vessel. The mixed liquid in the second reaction vessel can be introduced into the first reaction vessel through a circulation pipeline and mixed with the third mixed liquid.

[0077] According to embodiments of this application, in order to accelerate the reaction efficiency, the mixed gas and SO3 gas can be contacted in reverse, for example, the two gaseous reactants can be introduced from the top and bottom of the reaction vessel respectively. This effectively increases the contact area and significantly improves the reaction efficiency.

[0078] According to an embodiment of this application, the reaction temperature between the first mixed gas and SO3 is 50°C to 80°C. For example, it can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, or any range of the above values. Within the above temperature range, the rate at which HCl gas in the first mixed gas reacts with SO3 to produce chlorosulfonic acid can be accelerated, thereby improving production efficiency.

[0079] According to embodiments of this application, the pressure at which the first mixed gas reacts with SO3 is 0 bar to 1.5 bar. For example, it can be 0 bar, 0.1 bar, 0.2 bar, 0.3 bar, 0.4 bar, 0.5 bar, 0.6 bar, 0.7 bar, 0.8 bar, 0.9 bar, 1.0 bar, 1.1 bar, 1.2 bar, 1.3 bar, 1.4 bar, 1.5 bar, etc., or any range of the above values. By controlling the pressure within the above range, it helps to increase the rate at which HCl gas in the first mixed gas reacts with SO3 gas in the first mixed liquid to produce chlorosulfonic acid, thus accelerating the reaction process.

[0080] It is understandable that when the first mixed gas reacts with SO3 in multiple steps, the temperature and pressure of each step can be consistent with the above-mentioned temperature and pressure, which will not be elaborated further here.

[0081] In some embodiments of this application, the volume ratio of the first mixed gas to SO3 gas is (1 to 1.5):1. For example, it can be 1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, or any range of the above values. Therefore, by keeping the volume ratio of the first mixed gas to SO3 gas within the above range, the efficient reaction between HCl gas and SO3 gas in the first mixed gas is promoted, the completeness of the reaction is improved, the content of unreacted HCl gas in the first mixed gas is reduced, and the recovery efficiency of HCl gas in the mixed tail gas is improved.

[0082] In some embodiments of this application, the temperature of the SO3 gas is 80°C to 110°C. For example, it can be 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, or any range of the above values. Therefore, by controlling the temperature of the SO3 gas within the above range, the reaction can be promoted, the rate of reaction between the SO3 gas and the HCl gas in the first mixed gas to produce chlorosulfonic acid can be increased, and the recovery rate of the HCl gas can be improved.

[0083] In some embodiments of this application, the purity of the SO3 gas is greater than or equal to 97%. For example, it can be 97%, 98%, 99%, 99.3%, 99.5%, 99.7%, 99.9%, 100%, or any range of the above values. Therefore, by controlling the purity of the sulfur trioxide gas within the above range, the reaction efficiency between the sulfur trioxide gas and hydrogen chloride gas can be improved, which helps to obtain high-purity chlorosulfonic acid and increase the chlorosulfonic acid content in the final product.

[0084] S300: The second mixed gas is acid-washed to absorb SO3 in the second mixed gas, resulting in a third mixed gas containing SO2 and HCl.

[0085] In this step, the main reaction is the absorption of SO3 from the second gas mixture by the acid washing absorbent. Acid washing can effectively recover unreacted SO3 gas from the second gas mixture.

[0086] In some specific embodiments, the acid washing can be carried out using sulfuric acid with a mass concentration of 95% to 99% (e.g., 95%, 96%, 97%, 98%, 99%, etc.). This results in better absorption of SO3 gas, effectively reducing its content in the second gas mixture and facilitating the subsequent acquisition of SO2 gas with higher purity.

[0087] In some embodiments, the specific steps and parameters of acid washing are not particularly limited. As long as SO3 gas can be effectively absorbed, they can be selected according to the actual situation, and this application has no particular restrictions. As an example, the acid washing step can be carried out in an acid washing tower, for example, by referring to conventional techniques.

[0088] S400: The third mixed gas is washed with water to absorb HCl from the third mixed gas, thereby obtaining SO2 gas.

[0089] In this step, the main reaction is the absorption of HCl by water to produce dilute hydrochloric acid. This effectively absorbs unreacted HCl gas from the third gas mixture, yielding dilute hydrochloric acid and high-purity SO2 gas.

[0090] In some embodiments, water washing can be performed in one step or in multiple steps. Considering both the absorption efficiency and cost of HCl gas, two-step water washing can be performed.

[0091] In some embodiments, the specific steps and parameters of the water washing are not particularly limited. As long as HCl gas can be effectively absorbed, they can be selected according to the actual situation, and this application has no particular restrictions. As an example, the water washing step can be carried out in a water washing tower, for example, by referring to conventional techniques.

[0092] To remove any impurities that may be present in the mixed exhaust gas, refer to... Figure 2 Before reacting the mixed exhaust gas with the first mixture, the method further includes: S500: washing and drying the mixed exhaust gas. This removes impurities and moisture from the exhaust gas, purifying it.

[0093] In some embodiments of this application, sulfuric acid is used to wash and dry the mixed tail gas, wherein the mass concentration of the sulfuric acid is 90% to 99% by mass. For example, it can be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, etc., or any range of the above values. Thus, by keeping the mass concentration of sulfuric acid within the above concentration range, impurities in the mixed tail gas can be removed, achieving purification of the mixed tail gas; simultaneously, moisture in the mixed tail gas is absorbed, achieving drying of the mixed tail gas.

[0094] In some embodiments, the washing and drying of the mixed tail gas can be carried out in a drying tower. As an example, the mixed tail gas can be brought into contact with sulfuric acid in the drying tower. For example, the mixed tail gas can be introduced into the sulfuric acid from the bottom or lower part. The mixed tail gas is introduced from bottom to top, which can fully contact the sulfuric acid, thereby effectively removing moisture and impurities from the mixed tail gas.

[0095] Therefore, by employing the method of this application, the efficient separation and resource utilization of HCl and SO2 gases in mixed tail gas are achieved. Specifically, HCl gas is reacted with SO3 gas to efficiently synthesize chlorosulfonic acid, thereby recovering and utilizing the HCl in the mixed tail gas. Furthermore, the separated SO2 gas can be reused in the production of sulfuric acid or sodium sulfite, while the generated sulfuric acid can be used as an absorbent in the aforementioned washing, drying, and pickling steps, achieving the recycling of raw materials. This process not only reduces tail gas emissions and environmental pollution but also reduces tail gas treatment costs and conserves resources through the recycling of raw materials.

[0096] Device for treating exhaust gas

[0097] This application discloses an apparatus for treating exhaust gas, which is used to implement the aforementioned method for treating mixed exhaust gas. According to an embodiment of this application, see... Figure 3 The apparatus includes: a refining tower 1, a synthesis tower 2, an acid washing tower 3, a water washing tower 4, and a finished product tank 5. Each component will be described in detail below.

[0098] In some embodiments of this application, the purification tower 1 is used to react a mixed tail gas containing SO2 and HCl with a first mixed liquid containing chlorosulfonic acid and SO3 to obtain chlorosulfonic acid and a first mixed gas containing SO2 and HCl.

[0099] Specifically, the first mixture can be introduced into the purification tower from the top, and the mixed tail gas can be introduced into the first mixture in the purification tower from the bottom. This allows the HCl in the mixed tail gas to fully contact and react with the SO3 in the first mixture. The resulting chlorosulfonic acid product can be output from the top of the purification tower and transported to the finished product tank 5 for storage, while the first mixed gas can be output from the top of the purification tower and enter the subsequent process.

[0100] In some embodiments of this application, the synthesis tower 2 is connected to the purification tower 1. The first mixed gas obtained from the reaction in the purification tower 1 is transported to the synthesis tower, and SO3 gas is simultaneously introduced into the synthesis tower. The HCl in the first mixed gas reacts with the SO3 gas in the synthesis tower to obtain a second mixed liquid containing chlorosulfonic acid and a second mixed gas containing SO2, HCl and SO3.

[0101] In some embodiments of this application, reference is made to Figure 4 The synthesis tower 2 may include a first synthesis tower 21 and a second synthesis tower 22 connected in series. The first synthesis tower 21 is connected to the purification tower 1, and the second synthesis tower 22 is connected to the pickling tower 3.

[0102] Specifically, the second mixed gas can be introduced into the first synthesis tower through the lower part, and SO3 gas can be introduced into the first synthesis tower through the upper part. The second mixed gas and SO3 gas come into countercurrent contact in the first synthesis tower and react to generate chlorosulfonic acid, resulting in a third mixed liquid and a fourth mixed gas. The fourth mixed gas is discharged from the top of the first synthesis tower and then introduced into the second synthesis tower from the lower part. In the second synthesis tower, HCl in the fourth mixed gas reacts with SO3 gas to generate chlorosulfonic acid. At the same time, HCl in the fourth mixed gas also reacts with SO3 in the mixed liquid in the second synthesis tower to generate chlorosulfonic acid, resulting in a fourth mixed liquid and a second mixed gas. The second mixed gas is discharged from the top of the second synthesis tower and enters the subsequent process, while the fourth mixed liquid is discharged from the bottom of the second synthesis tower through a circulation pipeline and transported from the top of the first synthesis tower to the first synthesis tower. The fourth mixed liquid and the third mixed liquid are mixed in the second synthesis tower to form the mixed liquid in the second synthesis tower, i.e., the second mixed liquid.

[0103] Furthermore, the mixture in the first synthesis tower can be discharged from the bottom of the first synthesis tower through a circulation pipeline and fed into the purification tower from the top to absorb HCl in the mixed tail gas. In other words, the mixture in the first synthesis tower can be used as the first mixture to be fed into the purification tower to react with the mixed tail gas.

[0104] In some embodiments of this application, reference is made to Figure 5The synthesis tower 2 may include a first synthesis tower 21, a second synthesis tower 22 and a third synthesis tower 23 connected in series. The first synthesis tower 21 is connected to the purification tower 1 and the third synthesis tower 23 is connected to the acid washing tower 3.

[0105] Specifically, the first mixed gas can be introduced into the first synthesis tower through the lower part, while SO3 gas can be introduced into the first synthesis tower through the upper part. The first mixed gas and SO3 gas come into counter-current contact in the first synthesis tower and react to produce chlorosulfonic acid, yielding a third mixed liquid and a fourth mixed gas. The fourth mixed gas is discharged from the top of the first synthesis tower and then introduced into the second synthesis tower from the lower part. In the second synthesis tower, the HCl in the fourth mixed gas reacts with the SO3 gas to produce chlorosulfonic acid. Simultaneously, the HCl in the fourth mixed gas also reacts with the SO3 in the mixed liquid in the second synthesis tower to produce chlorosulfonic acid, yielding a fourth mixed liquid and a fifth mixed gas. The fifth mixed gas is discharged from the top of the second synthesis tower and then introduced into the third synthesis tower from the lower part. In the tower, HCl in the fifth mixed gas reacts with SO3 gas to produce chlorosulfonic acid. At the same time, HCl in the fifth mixed gas also reacts with SO3 in the mixed liquid in the third synthesis tower to produce chlorosulfonic acid, resulting in a second mixed gas and a fifth mixed liquid. The second mixed gas can be discharged from the top of the third synthesis tower to enter the next process, while the fifth mixed liquid is discharged from the bottom of the third synthesis tower through a circulation pipeline and input into the second synthesis tower from the top. The fifth mixed liquid and the fourth mixed liquid are mixed in the second synthesis tower to form the mixed liquid in the second mixed tower. The mixed liquid in the second synthesis tower is discharged from the bottom of the second synthesis tower through a circulation pipeline and input into the first synthesis tower from the top. The mixed liquid in the second synthesis tower and the third mixed liquid are mixed in the first synthesis tower to form the mixed liquid in the first synthesis tower.

[0106] Furthermore, the mixture in the first synthesis tower can be discharged from the bottom of the first synthesis tower through a circulation pipeline and fed into the purification tower from the top to absorb HCl in the mixed tail gas. In other words, the mixture in the first synthesis tower can be used as the first mixture to be fed into the purification tower to react with the mixed tail gas.

[0107] In some embodiments of this application, the mass concentration of chlorosulfonic acid in the mixture in the first synthesis tower is 89%-95% (specifically, 89%, 90%, 91%, 92%, 93%, 94%, 95%, etc.); the mass concentration of chlorosulfonic acid in the mixture in the second synthesis tower is 50%-60% (specifically, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, etc.); and the mass concentration of chlorosulfonic acid in the mixture in the third synthesis tower is 30%-50% (specifically, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, etc.). Specifically, the first mixed gas passes through the first, second, and third synthesis towers in sequence. The content of HCl and other substances in the first mixed gas gradually decreases. Therefore, the mass concentration of chlorosulfonic acid in the resulting mixture gradually decreases. However, after the reaction in multiple synthesis towers, the absorption rate of HCl can be effectively improved.

[0108] In some embodiments of this application, reference is made to Figure 6 The device also includes an HCl scrubbing tower 6, which is connected to the purification tower 1 and is used to scrub and dry the mixed exhaust gas.

[0109] Specifically, before entering the refining tower, the mixed tail gas is pre-passed into the HCl scrubbing tower from the bottom. The HCl scrubbing tower is equipped with sulfuric acid. The mixed tail gas is passed into the sulfuric acid and comes into full contact with it. The sulfuric acid absorbs the moisture and impurities in the mixed tail gas. After being washed and dried, the mixed tail gas is discharged from the top of the HCl scrubbing tower and then passed into the refining tower from the bottom for the next process.

[0110] In some embodiments of this application, reference is made to Figure 7 The device further includes a gas-liquid separator 7, which is disposed between the synthesis tower 2 and the acid washing tower 3. The gas-liquid separator 7 is connected to both the synthesis tower 3 and the acid washing tower 3 and is used to separate the liquid in the second mixed gas.

[0111] Specifically, the second mixed gas discharged from the synthesis tower is fed into the gas-liquid separator through the feed port. In the gas-liquid separator, the liquid carried in the second mixed gas is separated. The separated gas is discharged from the gas-liquid separator through the discharge port and fed into the acid washing tower for acid washing.

[0112] In some embodiments of this application, reference is made to Figure 8 The water washing tower 4 includes a first water washing tower 41 and a second water washing tower 42 connected in series. This improves the HCl absorption rate and yields SO2 with higher purity.

[0113] Specifically, the third mixed gas discharged from the acid washing tower is introduced into the first water washing tower from the bottom. The absorbent in the first water washing tower absorbs the HCl in the third mixed gas to generate dilute hydrochloric acid, resulting in a sixth mixed gas. The sixth mixed gas is discharged from the top of the first water washing tower and introduced into the second water washing tower from the bottom. In the second water washing tower, the absorbent absorbs the HCl in the sixth mixed gas to generate dilute hydrochloric acid, resulting in SO2 gas.

[0114] Furthermore, the SO2 gas can be transported to a sulfuric acid preparation unit for the production of sulfuric acid. Therefore, the device of this application can effectively treat the exhaust gas and utilize it as a resource, greatly reducing environmental pollution and improving economic efficiency.

[0115] In some embodiments of this application, reference is made to Figure 8 The device of this application contains a plurality of condensers 8 for controlling the temperature in the corresponding components.

[0116] It is understood that the reactions and specific parameters in the above-mentioned components are consistent with those described in the mixed exhaust gas treatment method of the first aspect of this application, and will not be repeated here.

[0117] The following reference Figure 8 This application describes in detail the working process of the exhaust gas treatment method and apparatus.

[0118] Specifically, a mixed tail gas containing approximately 40% HCl and approximately 30% SO2 is introduced into the HCl scrubbing tower from the bottom. The HCl scrubbing tower contains sulfuric acid with a mass concentration of 90%–99%. The mixed tail gas is introduced into the sulfuric acid and comes into full contact with it. The sulfuric acid absorbs moisture and impurities from the mixed tail gas. The washed and dried mixed tail gas is discharged from the top of the HCl scrubbing tower and then introduced into the first mixed liquid in the purification tower from the bottom. The first mixed liquid can be introduced into the purification tower from the top. In the purification tower, the process is controlled... The temperature is controlled at 50℃~80℃ and the pressure at 0bar~1.5bar. HCl in the mixed tail gas fully contacts and reacts with SO3 in the first mixed liquid to obtain a first mixed gas and a chlorosulfonic acid product with a mass concentration greater than or equal to 99%. The chlorosulfonic acid product exits the refining tower from the top and is transported to the finished product tank 5 for storage. The first mixed gas can exit the refining tower from the top and enter the first synthesis tower through the bottom. SO3 gas can enter the first synthesis tower from the top. The temperature is controlled at 50℃~80℃ and the pressure at 0bar~1.5bar. The HCl in the mixed tail gas fully contacts and reacts with SO3 in the first mixed liquid to obtain a first mixed gas and a chlorosulfonic acid product with a mass concentration greater than or equal to 99%. The temperature in the first synthesis tower is 50℃~80℃, and the pressure is 0bar~1.5bar. The volume ratio of the first mixed gas to SO3 gas introduced into the first synthesis tower is (1~1.5):1. The temperature of the SO3 gas is 80℃~110℃. The first mixed gas and SO3 gas are in countercurrent contact in the first synthesis tower and react to produce chlorosulfonic acid, resulting in a third mixed liquid and a fourth mixed gas. The fourth mixed gas is discharged from the top of the first synthesis tower and then introduced into the second synthesis tower from the bottom. In the second synthesis tower, the temperature is controlled... The temperature is 50℃~80℃, and the pressure is 0bar~1.5bar. HCl in the fourth mixed gas reacts with SO3 gas to produce chlorosulfonic acid. Simultaneously, HCl in the fourth mixed gas also reacts with SO3 in the mixed liquid in the second synthesis tower to produce chlorosulfonic acid, resulting in a fourth mixed liquid and a fifth mixed gas. The fifth mixed gas is discharged from the top of the second synthesis tower and introduced into the third synthesis tower from the bottom. In the third synthesis tower, the temperature in the first synthesis tower is controlled at 50℃~80℃, and the pressure is 0bar~1.5bar.At 5 bar, HCl in the fifth gas mixture reacts with SO3 to produce chlorosulfonic acid. Simultaneously, HCl in the fifth gas mixture also reacts with SO3 in the mixture in the third synthesis tower to produce chlorosulfonic acid, resulting in a second gas mixture and a fifth liquid mixture. The fifth liquid mixture is discharged from the bottom of the third synthesis tower through a circulation pipeline and input into the second synthesis tower from the top. The fifth and fourth liquid mixtures are mixed in the second synthesis tower to form the liquid mixture there. The liquid mixture in the second synthesis tower is discharged from the bottom of the second synthesis tower through a circulation pipeline and input into the first synthesis tower from the top. The liquid mixture in the second and third synthesis towers are mixed in the first synthesis tower to form the liquid mixture there. The liquid mixture in the first synthesis tower can be discharged from the bottom of the first synthesis tower through a circulation pipeline and input into the purification tower from the top, serving as the first liquid mixture introduced into the purification tower to mix with the tail gas. The reaction proceeds, and the second mixed gas exits from the top of the third synthesis tower and enters the gas-liquid separator through the feed inlet. In the gas-liquid separator, the liquid carried in the second mixed gas is separated. The separated gas exits from the gas-liquid separator through the outlet and enters the acid washing tower from the bottom. There, it reacts with the absorbent in the acid washing tower to absorb SO3 gas, resulting in a third mixed gas containing SO2 and HCl. This third mixed gas exits from the top of the acid washing tower and enters the first water washing tower from the bottom. The absorbent in the first water washing tower absorbs the HCl in the third mixed gas, generating dilute hydrochloric acid, resulting in a sixth mixed gas. This sixth mixed gas exits from the top of the first water washing tower and enters the second water washing tower from the bottom. In the second water washing tower, the absorbent absorbs the HCl in the sixth mixed gas, generating dilute hydrochloric acid, resulting in SO2 gas.

[0119] Joint System

[0120] According to embodiments of this application, a combined system is also proposed. (Refer to...) Figure 9 The combined system includes a fluoroamine preparation unit 10, a mixed tail gas treatment unit 20 (described above), connected to the fluoroamine preparation unit 10, receiving the mixed tail gas from the fluoroamine preparation unit, and a sulfuric acid preparation unit 30, connected to the mixed tail gas treatment unit, receiving SO2 gas from the mixed tail gas treatment unit. Therefore, the fluoroamine preparation unit, the mixed tail gas treatment unit, and the sulfuric acid preparation unit can be used in combination to reduce tail gas emissions and produce commercially valuable chlorosulfonic acid products, effectively reducing environmental pollution and improving economic benefits.

[0121] In some embodiments of this application, the sulfuric acid preparation apparatus includes a nicotinic acid component, which is connected to the mixed tail gas treatment device to provide SO3 gas to the mixed tail gas treatment device. Thus, the SO3 gas purity is above 99%, which is beneficial for obtaining high-quality chlorosulfonic acid.

[0122] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0123] Example 1

[0124] use Figure 10 The exhaust gas treatment device shown treats the mixed exhaust gas (containing approximately 50% hydrogen chloride and 49% sulfur dioxide) generated by the amine fluorooxide preparation unit. Specifically, the HCl scrubbing tower uses 95% sulfuric acid in a circulating cycle to absorb impurities and moisture from the mixed exhaust gas. The SO3 gas introduced into the first synthesis tower comes from the nicotinic acid section of the sulfuric acid unit, with a purity of over 99%, and its temperature entering the synthesis tower is controlled at 100°C. The volume ratio of the mixed exhaust gas to SO3 gas introduced into the first synthesis tower is approximately 1.2:1. In the acid washing tower, 98% sulfuric acid is used to circulate and absorb SO3. When the sulfuric acid becomes turbid, it is transferred to a waste acid storage tank. The SO2 gas obtained in the second water washing tower is connected to the sulfuric acid unit by an exhaust gas fan, serving as a raw material for sulfuric acid / sodium sulfite production.

[0125] Examples 2 to 21

[0126] The mixed exhaust gas was treated according to the method described in Example 1, with the differences shown in Table 1.

[0127] Comparative Example 1

[0128] The difference from Example 1 is that Comparative Example 1 did not use a purification tower for the reaction; that is, the mixture in the first synthesis tower was used as the chlorosulfonic acid product, while the mixed tail gas discharged from the HCl washing tower was directly fed into the first synthesis tower.

[0129] Table 1

[0130]

[0131] The concentration of the final chlorosulfonic acid product in Examples 1-21 and Comparative Example 1 was tested. The specific testing method was carried out in accordance with the method for testing the concentration of industrial chlorosulfonic acid in GB / T13549-2016.

[0132]

[0133]

[0134] The test data above shows that the method of this application can be used to treat exhaust gas and obtain high-purity chlorosulfonic acid, which can be used or sold directly, realizing the resource recycling of exhaust gas. At the same time, the cost is low, the utilization rate is high, and the waste production is low.

[0135] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0136] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for treating mixed exhaust gases, characterized in that, include: The mixed tail gas containing SO2 and HCl is reacted with the first mixed liquid containing chlorosulfonic acid and SO3 to obtain chlorosulfonic acid product and the first mixed gas containing SO2 and HCl. The first mixed gas is reacted with SO3 gas to obtain a second mixed liquid containing chlorosulfonic acid and SO3 and a second mixed gas containing SO2, HCl and SO3; The second mixed gas is acid-washed to absorb SO3 from it, resulting in a third mixed gas containing SO2 and HCl. The third mixed gas is washed with water to absorb HCl, yielding SO2 gas.

2. The method according to claim 1, characterized in that, The first mixture is composed of the second mixture.

3. The method according to claim 1, characterized in that, At least one of the following conditions must be met: The chlorosulfonic acid product has a mass concentration of chlorosulfonic acid greater than or equal to 99%; The mass concentration of chlorosulfonic acid in the first mixture is 89%-95%; The HCl content in the mixed exhaust gas is 30% to 50%.

4. The method according to claim 1, characterized in that, The reaction of the first mixed gas with SO3 includes: The first mixed gas undergoes a first reaction with SO3 to obtain a third mixed liquid containing chlorosulfonic acid and a fourth mixed gas containing SO2, HCl and SO3; The HCl and SO3 in the fourth mixed gas undergo a second reaction to obtain a fourth mixed liquid containing chlorosulfonic acid and a second mixed gas containing the second mixed gas. The fourth mixture and the third mixture are mixed to obtain the second mixture.

5. The method according to claim 4, characterized in that, The reaction of the first mixed gas with SO3 further includes: The HCl and SO3 in the fifth mixed gas undergo a third reaction to obtain a fifth mixed liquid containing chlorosulfonic acid and a sixth mixed gas containing SO2, HCl and SO3; The fifth mixture, the fourth mixture, and the third mixture are mixed to obtain the second mixture.

6. The method according to claim 1, characterized in that, The volume ratio of the first mixed gas to SO3 gas is (1-1.5):

1.

7. The method according to claim 1, characterized in that, At least one of the following conditions must be met: The temperature of the SO3 gas is 80℃~110℃; The purity of the SO3 gas is greater than or equal to 97%.

8. The method according to claim 1, characterized in that, The pickling is carried out using sulfuric acid with a mass concentration of 95% to 99%.

9. The method according to any one of claims 1-8, characterized in that, Before the mixed exhaust gas reacts with the first mixture, the method further includes washing and drying the mixed exhaust gas.

10. The method according to claim 9, characterized in that, The mixed tail gas was washed and dried using sulfuric acid with a mass concentration of 90% to 99%.

11. The method according to claim 1, characterized in that, Meet at least one of the following: The temperature at which the mixed exhaust gas reacts with the first mixed liquid is 50°C to 80°C. The pressure at which the mixed exhaust gas reacts with the first mixture is 0 bar to 1.5 bar; The reaction temperature between the first mixed gas and SO3 gas is 50℃~80℃; The pressure at which the first mixed gas reacts with SO3 gas is 0 bar to 1.5 bar.

12. An apparatus for implementing the method according to any one of claims 1 to 11, characterized in that, include: A purification tower is used to react a mixed tail gas containing SO2 and HCl with a first mixed liquid containing chlorosulfonic acid and SO3 to obtain chlorosulfonic acid and a first mixed gas containing SO2 and HCl. A synthesis tower, connected to the purification tower, is used to react the first mixed gas with SO3 to obtain a second mixed liquid containing chlorosulfonic acid and a second mixed gas containing SO2, HCl and SO3. A pickling tower, connected to the synthesis tower, is used to pickle the second mixed gas to obtain a third mixed gas containing SO2 and HCl; A water washing tower, connected to the acid washing tower, is used to wash the third mixed gas with water to obtain SO2 gas; The finished product tank, connected to the refining tower, is used to store the chlorosulfonic acid finished product.

13. The apparatus according to claim 12, characterized in that, The synthesis tower includes: A first synthesis tower and a second synthesis tower are connected in series, the first synthesis tower being connected to the purification tower and the second synthesis tower being connected to the pickling tower.

14. The apparatus according to claim 13, characterized in that, The synthesis tower also includes a third synthesis tower connected in series with the first synthesis tower and the second synthesis tower. The first synthesis tower is connected to the purification tower, and the third synthesis tower is connected to the pickling tower.

15. The apparatus according to claim 14, characterized in that, At least one of the following conditions must be met: The mass concentration of chlorosulfonic acid in the mixture in the first synthesis tower is 89%-95%; The mass concentration of chlorosulfonic acid in the mixture in the second synthesis tower is 50%-60%. The mass concentration of chlorosulfonic acid in the mixture in the third synthesis tower is 30%-50%.

16. The apparatus according to claim 12, characterized in that, Also includes: An HCl scrubbing tower, which is connected to the purification tower, is used to scrub and dry the mixed exhaust gas.

17. The apparatus according to claim 12, characterized in that, Also includes: A gas-liquid separator is disposed between the synthesis tower and the acid washing tower, and is connected to both the synthesis tower and the acid washing tower respectively, for separating the liquid in the second mixed gas.

18. The apparatus according to claim 12, characterized in that, The water washing tower includes a first water washing tower and a second water washing tower connected in series.

19. A combined system, characterized in that, include: Fluorooxyamine preparation apparatus; The mixed exhaust gas treatment device according to any one of claims 12 to 18 is connected to the fluorinated amine preparation device and receives mixed exhaust gas from the fluorinated amine preparation device; The sulfuric acid preparation device is connected to the mixed tail gas treatment device and receives SO2 gas from the mixed tail gas treatment device.

20. The combined system according to claim 19, characterized in that, The sulfuric acid preparation device includes a nicotinic acid component, which is connected to the mixed tail gas treatment device and is used to provide SO3 gas to the mixed tail gas treatment device.

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