A process and system for catalytic incineration of claus tail gas to produce sulfuric acid
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ACRE COKING & REFRACTORY ENG CONSULTING CORP DALIAN MCC
- Filing Date
- 2026-03-13
- Publication Date
- 2026-06-26
Smart Images
Figure CN121823486B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of industrial exhaust gas purification and resource utilization technology, and in particular to a Claus exhaust gas catalytic combustion process and system for sulfuric acid production. Background Technology
[0002] The traditional Claus sulfur recovery process (a chemical process that converts acidic gases containing hydrogen sulfide into elemental sulfur) consists of two parts: the Claus main process and the Claus tail gas treatment process. Because the Claus reaction itself has a relatively small equilibrium constant, the sulfur recovery rate is typically below 97%, necessitating a Claus tail gas treatment process to further improve the sulfur recovery rate and reduce pollutant emissions. Therefore, the level of Claus tail gas treatment technology directly determines the overall sulfur recovery rate and the degree of compliance with tail gas emission standards.
[0003] Among the current Claus tail gas treatment technologies, the Scott (SCOT) process is the most representative and widely used. This process focuses on deep desulfurization and recovery of Claus tail gas, employing a closed-loop process of "hydrogenation reduction + amine absorption + desorption regeneration." First, sulfur oxides such as SO2 and Sx in the tail gas are reduced to H2S under the action of a hydrogenation catalyst. Then, H2S is selectively absorbed by an amine solvent. The H2S-rich amine solution is desorbed and regenerated to release a high concentration of H2S, which is then returned to the Claus unit to participate in the sulfur recovery reaction, achieving sulfur resource recycling. The purified gas at the top of the absorption tower is then discharged after high-temperature incineration.
[0004] The advantages of the Scott process are high total sulfur recovery rate, strong operational flexibility, mature and reliable technology, and no secondary pollution. However, it also has obvious technical shortcomings, namely high construction investment and operating costs, complex process flow, dependence on external hydrogen sources and fuels, and high sulfur content in exhaust gas, which can no longer meet the requirements of the latest standards. It must be matched with deep desulfurization to achieve compliant emissions.
[0005] Catalytic incineration is a tail gas purification technology based on the action of catalysts. Its core principle is to use the catalytic activity of catalysts under medium and low temperature conditions to promote the complete oxidation reaction of combustible pollutants in tail gas, transforming them into harmless or resource-recoverable products, thereby achieving the dual goals of waste gas purification and resource recovery. Summary of the Invention
[0006] This invention provides a process and system for producing sulfuric acid from Claus tail gas through catalytic combustion. Utilizing catalytic combustion technology, the activation energy of the reaction is significantly reduced under the action of a catalyst. By introducing oxygen-containing gas, sulfur-containing components such as H2S and Sx in the Claus tail gas are catalytically oxidized to SO2 under medium-temperature conditions, while combustible components such as H2 and CO in the tail gas are catalytically oxidized to H2O and CO2. The heat of reaction released during the process is fully recovered and used to preheat the Claus tail gas to be treated, achieving efficient utilization of thermal energy. The SO2 gas generated by catalytic combustion is converted using a wet contact method and further catalytically oxidized to SO3 under the action of a vanadium catalyst. Subsequently, the generated SO3 gas is condensed and cooled, allowing it to combine with water vapor in the tail gas to directly generate concentrated sulfuric acid. For the residual tail gas after treatment, hydrogen peroxide oxidation or ozone oxidation is used to remove residual SO2, ensuring that the tail gas emissions meet environmental protection standards.
[0007] To achieve the above objectives, the present invention employs the following technical solution:
[0008] A process for producing sulfuric acid by catalytic combustion of Claus tail gas includes a sulfur component catalytic combustion process, a combustible component catalytic combustion process, an acid production process, and a desulfurization process. The sulfur component catalytic combustion process involves catalytically oxidizing the sulfur-containing components in the Claus tail gas to SO2 under the catalysis of a medium-temperature catalyst. The combustible component catalytic combustion process involves catalytically oxidizing the combustible components in the Claus tail gas to H2O and CO2 under the catalysis of a medium-temperature catalyst. The acid production process uses a wet contact method to catalytically oxidize SO2 to SO3 under the action of a vanadium catalyst. The generated SO3 gas is condensed and cooled before combining with water vapor in the Claus tail gas to directly produce commercial-grade concentrated sulfuric acid. The desulfurization process uses hydrogen peroxide or ozone oxidation to remove residual SO2 from the remaining tail gas after acid production, ensuring that the final tail gas meets emission standards.
[0009] The heat released during the catalytic combustion of combustible components is used to preheat the Claus tail gas before it enters the catalytic combustion process of sulfur components. When the preheating temperature of the Claus tail gas is greater than the set temperature, the process flow is: catalytic combustion of sulfur components → catalytic combustion of combustible components → acid production → desulfurization.
[0010] The heat released during the catalytic combustion of combustible components is used to preheat the Claus tail gas before it enters the catalytic combustion process of sulfur components. When the preheating temperature of the Claus tail gas is less than or equal to the set temperature, the process flow is: catalytic combustion of combustible components → catalytic combustion of sulfur components → acid production → desulfurization.
[0011] The medium-temperature catalyst is a catalyst with silicon dioxide or alumina as the support and vanadium and iron metal oxides as the active components; the catalytic combustion temperature of the sulfur component is 265-420℃, and the oxygen content in the tail gas after catalytic combustion is 0.5-6% Vol.
[0012] The intermediate-temperature catalyst II is a catalyst with alumina as a support and molybdenum oxide and cobalt oxide as active components; the catalytic combustion temperature of the combustible components is 200-550℃, and the oxygen content in the tail gas after catalytic combustion is 0.5-8% Vol.
[0013] Air or other oxygen-containing gas is used as a cold source to absorb and remove the heat of reaction and cooling in the acid production process, and then becomes hot air after heat exchange; the hot air is used to provide the oxygen required for the reaction in the catalytic combustion process of sulfur components, the catalytic combustion process of combustible components and the acid production process.
[0014] The desulfurization process removes SO2 from the Claus tail gas and generates a small amount of dilute sulfuric acid. The dilute sulfuric acid is added to the concentrated sulfuric acid produced in the acid production process to finally obtain commercial grade concentrated sulfuric acid with a concentration of ≥93%, and all indicators meet the quality requirements of GB / T534 "Industrial Sulfuric Acid".
[0015] A Claus tail gas catalytic combustion system for sulfuric acid production includes a process gas heat exchanger, a sulfur component reactor, a combustible component reactor, an SO2 converter, a condenser, a cooling tower, and a desulfurization tower. The sulfur component reactor is filled with a first medium-temperature catalyst; the combustible component reactor is filled with a second medium-temperature catalyst; the SO2 converter is filled with multiple layers of V2O5 catalyst beds, with inter-bed heat exchangers connected to the sulfur production waste heat boiler; a process gas cooler is located at the bottom of the SO2 converter, and the process gas cooler and the combustible component reactor are respectively connected to a steam drum; the cooling tower is equipped with a circulating coolant spraying system, and the desulfurization tower is equipped with a circulating desulfurization liquid spraying system.
[0016] The first heat exchange medium inlet of the process gas heat exchanger is connected to Claus tail gas pipeline one, and the first heat exchange medium outlet of the process gas heat exchanger is connected to the cold process gas inlet of the sulfur component reactor. The hot process gas outlet of the sulfur component reactor is connected to the hot process gas inlet of the combustible component reactor through hot process gas pipeline one, and the hot process gas outlet of the combustible component reactor is connected to the second heat exchange medium inlet of the process gas heat exchanger through hot process gas pipeline two. The second heat exchange medium outlet of the process gas heat exchanger is connected to the hot process gas inlet of the SO2 converter, and the process gas outlet of the SO2 converter is connected to the process gas inlet of the condenser. The tail gas outlet of the condenser is connected to the tail gas inlet of the cooling tower. The air inlet of the condenser is connected to air inlet pipeline one, and an air fan is installed on air inlet pipeline one. The hot air outlet of the condenser is connected to the air inlet pipeline, hot process gas pipeline one, hot process gas pipeline two, and Claus tail gas pipeline one, respectively. The condenser is provided with a sulfuric acid outlet. The tail gas outlet of the cooling tower is connected to the tail gas inlet of the desulfurization tower, and the desulfurization tower is provided with a purified tail gas outlet.
[0017] A Claus tail gas catalytic combustion system for sulfuric acid production includes a process gas heat exchanger, a sulfur component reactor, a combustible component reactor, an SO2 converter, a condenser, a cooling tower, and a desulfurization tower. The sulfur component reactor is filled with a first medium-temperature catalyst; the combustible component reactor is filled with a second medium-temperature catalyst; the SO2 converter is filled with multiple layers of V2O5 catalyst beds, with inter-bed heat exchangers between each V2O5 catalyst bed; a process gas cooler is located at the bottom of the SO2 converter, and the inter-bed heat exchangers and the process gas cooler are respectively connected to a waste heat boiler for sulfur production; the cooling tower is equipped with a circulating coolant spraying system, and the desulfurization tower is equipped with a circulating desulfurization liquid spraying system.
[0018] The first heat exchange medium inlet of the process gas heat exchanger is connected to Claus tail gas pipeline two, and the first heat exchange medium outlet is connected to the cold process gas inlet of the combustible component reactor. The hot process gas outlet of the combustible component reactor is connected to the second heat exchange medium inlet of the process gas heat exchanger via hot process gas pipeline three. The second heat exchange medium outlet of the process gas heat exchanger is connected to the hot process gas inlet of the sulfur component reactor. The hot process gas outlet of the sulfur component reactor is connected to the hot process gas inlet of the SO2 converter via hot process gas pipeline four. The process gas outlet of the SO2 converter is connected to the process gas inlet of the condenser. The tail gas outlet of the condenser is connected to the tail gas inlet of the cooling tower. The air inlet of the condenser is connected to air inlet pipeline two, and an air fan is installed on air inlet pipeline two. The hot air outlet of the condenser is connected to air inlet pipeline two, hot process gas pipeline three, hot process gas pipeline four, and Claus tail gas pipeline two, respectively. The condenser is provided with a sulfuric acid outlet. The tail gas outlet of the cooling tower is connected to the tail gas inlet of the desulfurization tower, and the desulfurization tower is provided with a purified tail gas outlet.
[0019] The sulfuric acid outlet of the condenser is connected to the intermediate acid tank via a sulfuric acid outlet pipeline. The intermediate acid tank is also connected to a commercial sulfuric acid pipeline. A sulfuric acid transfer pump and an acid cooler are installed on the commercial sulfuric acid pipeline. The circulating desulfurization liquid spraying system of the desulfurization tower is connected to the sulfuric acid outlet pipeline and the commercial sulfuric acid pipeline via a dilute sulfuric acid pipeline.
[0020] Compared with the prior art, the beneficial effects of the present invention are:
[0021] The SO2 gas generated by catalytic combustion is converted by wet contact method and further catalytically oxidized to SO3 under the action of vanadium catalyst. The generated SO3 gas is then condensed and cooled, so that it combines with water vapor in the tail gas to directly generate concentrated sulfuric acid. This breaks through the limitation of the traditional Claus tail gas treatment process, which is "only environmentally friendly but not profitable", and directly produces commercial-grade concentrated sulfuric acid, realizing high-value recovery of sulfur resources.
[0022] For the residual exhaust gas after treatment, hydrogen peroxide oxidation or ozone oxidation is used to remove the residual SO2 to ensure that the exhaust gas emissions meet the environmental protection standards.
[0023] The process flow has been significantly simplified, making operation simpler and more convenient. Attached Figure Description
[0024] Figure 1 This is a flow chart (system composition schematic diagram) of the Claus tail gas catalytic combustion process for sulfuric acid production in Embodiment 1 of the present invention.
[0025] Figure 2 This is a flowchart (system composition diagram) of the Claus tail gas catalytic combustion process for sulfuric acid production in Embodiment 2 of the present invention.
[0026] In the diagram: 1-Combustible component reactor; 2-Sulfur component reactor; 3-SO2 converter; 4-Condenser; 5-Cooling tower; 6-Desulfurization tower; 7-Chimney; 8-Acid intermediate tank; 9-Process gas heat exchanger; 10-Air fan; 11-Sulfuric acid transfer pump; 12-Acid cooler; 13-Circulating spray pump; 14-Spray liquid cooler; 15-Desulfurization liquid circulating pump; 16-Steam drum. Detailed Implementation
[0027] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:
[0028] like Figure 1 , Figure 2 As shown, the present invention discloses a Claus tail gas catalytic combustion process for sulfuric acid production, comprising a sulfur component catalytic combustion process, a combustible component catalytic combustion process, an acid production process, and a desulfurization process. The sulfur component catalytic combustion process involves catalytically oxidizing the sulfur-containing components in the Claus tail gas to SO2 under the catalytic action of a medium-temperature catalyst. The combustible component catalytic combustion process involves catalytically oxidizing the combustible components in the Claus tail gas to H2O and CO2 under the catalytic action of a medium-temperature catalyst. The acid production process employs a wet contact method, catalytically oxidizing SO2 to SO3 under the action of a vanadium catalyst. The generated SO3 gas, after condensation and cooling, combines with water vapor in the Claus tail gas to directly generate commercial-grade concentrated sulfuric acid. The desulfurization process uses hydrogen peroxide or ozone oxidation to remove residual SO2 from the remaining tail gas after acid production, ultimately ensuring that the tail gas meets emission standards.
[0029] The heat released during the catalytic combustion of combustible components is used to preheat the Claus tail gas before it enters the catalytic combustion process of sulfur components. When the preheating temperature of the Claus tail gas is greater than the set temperature, the process flow is: catalytic combustion of sulfur components → catalytic combustion of combustible components → acid production → desulfurization (e.g., Figure 1 (As shown). When the Claus tail gas preheating temperature is ≤ set temperature, the process flow is: catalytic combustion of combustible components → catalytic combustion of sulfur components → acid production → desulfurization (e.g. Figure 2 (As shown).
[0030] The medium-temperature catalyst is a catalyst with silicon dioxide or alumina as the support and vanadium and iron metal oxides as the active components; the catalytic combustion temperature of the sulfur component is 265-420℃, and the oxygen content in the tail gas after catalytic combustion is 0.5-6% Vol.
[0031] The intermediate-temperature catalyst II is a catalyst with alumina as a support and molybdenum oxide and cobalt oxide as active components; the catalytic combustion temperature of the combustible components is 200-550℃, and the oxygen content in the tail gas after catalytic combustion is 0.5-8% Vol.
[0032] Air or other oxygen-containing gas is used as a cold source to absorb and remove the heat of reaction and cooling in the acid production process, and then becomes hot air after heat exchange; the hot air is used to provide the oxygen required for the reaction in the catalytic combustion process of sulfur components, the catalytic combustion process of combustible components and the acid production process.
[0033] The desulfurization process removes SO2 from the Claus tail gas and generates a small amount of dilute sulfuric acid. The dilute sulfuric acid is added to the concentrated sulfuric acid produced in the acid production process to finally obtain commercial grade concentrated sulfuric acid with a concentration of ≥93%, and all indicators meet the quality requirements of GB / T534 "Industrial Sulfuric Acid".
[0034] like Figure 1 As shown, when using the process flow of sulfur component catalytic combustion → combustible component catalytic combustion → acid production → desulfurization, the Claus tail gas catalytic combustion sulfuric acid production system of the present invention includes a process gas heat exchanger 9, a sulfur component reactor 2, a combustible component reactor 1, an SO2 converter 3, a condenser 4, a cooling tower 5, and a desulfurization tower 6; the sulfur component reactor 2 is filled with a medium-temperature catalyst type I; the combustible component reactor 1 is filled with a medium-temperature catalyst type II; and the SO2 converter 3 is filled with a multi-layer V2O5 catalyst bed. Each V2O5 catalyst bed is equipped with an interbed heat exchanger, which is connected to the waste heat boiler for sulfur production. The bottom of the SO2 converter 3 is equipped with a process gas cooler, and the process gas cooler and the combustible component reactor are respectively connected to the steam drum 16. The cooling tower 5 is equipped with a circulating coolant spraying system (including coolant circulation pipes, circulating spraying pump 13, spraying liquid cooler 14 and coolant spraying device), and the desulfurization tower 6 is equipped with a circulating desulfurization liquid spraying system (including desulfurization liquid circulation pipes, desulfurization liquid circulation pump 15 and desulfurization liquid spraying device).
[0035] The first heat exchange medium inlet of the process gas heat exchanger 9 is connected to Claus tail gas pipeline one, and the first heat exchange medium outlet of the process gas heat exchanger 9 is connected to the cold process gas inlet of the sulfur component reactor 2. The hot process gas outlet of the sulfur component reactor 2 is connected to the hot process gas inlet of the combustible component reactor 1 through hot process gas pipeline one. The hot process gas outlet of the combustible component reactor 1 is connected to the second heat exchange medium inlet of the process gas heat exchanger 9 through hot process gas pipeline two. The second heat exchange medium outlet of the process gas heat exchanger 9 is connected to the hot process gas inlet of the SO2 converter 3. The process gas outlet of the SO2 converter 3 is connected to the process gas inlet of the condenser 4. The tail gas outlet of the condenser 4 is connected to the tail gas inlet of the cooling tower 5. The air inlet of the condenser 4 is connected to air inlet pipeline one, and an air fan 10 is installed on air inlet pipeline one. The hot air outlet of the condenser 4 is connected to the air inlet pipeline, hot process gas pipeline one, hot process gas pipeline two, and Claus tail gas pipeline one, respectively. The condenser 4 is provided with a sulfuric acid outlet. The tail gas outlet of the cooling tower 5 is connected to the tail gas inlet of the desulfurization tower 6, and the desulfurization tower 6 is provided with a purified tail gas outlet.
[0036] like Figure 2 As shown, when adopting the process flow of combustible component catalytic combustion → sulfur component catalytic combustion → acid production → desulfurization, the Claus tail gas catalytic combustion sulfuric acid production system of the present invention includes a process gas heat exchanger 9, a sulfur component reactor 2, a combustible component reactor 1, an SO2 converter 3, a condenser 4, a cooling tower 5, and a desulfurization tower 6; the sulfur component reactor 2 is filled with a medium-temperature catalyst type I; the combustible component reactor 1 is filled with a medium-temperature catalyst type II; the SO2 converter 3 is filled with multiple layers of V2O5 catalyst beds, and inter-bed heat exchangers are set between each V2O5 catalyst bed; a process gas cooler is set at the bottom of the SO2 converter 3, and the inter-bed heat exchanger and the process gas cooler are respectively connected to the sulfur production waste heat boiler; the cooling tower 5 is equipped with a circulating coolant spraying system, and the desulfurization tower 6 is equipped with a circulating desulfurization liquid spraying system.
[0037] The first heat exchange medium inlet of the process gas heat exchanger 9 is connected to Claus tail gas pipeline two, and the first heat exchange medium outlet is connected to the cold process gas inlet of the combustible component reactor 1. The hot process gas outlet of the combustible component reactor 1 is connected to the second heat exchange medium inlet of the process gas heat exchanger 9 through hot process gas pipeline three. The second heat exchange medium outlet of the process gas heat exchanger 9 is connected to the hot process gas inlet of the sulfur component reactor 2. The hot process gas outlet of the sulfur component reactor 2 is connected to the hot process gas inlet of the SO2 converter 3 through hot process gas pipeline four. The process gas outlet of the SO2 converter 3 is connected to the process gas inlet of the condenser 4. The tail gas outlet of the condenser 4 is connected to the tail gas inlet of the cooling tower 5. The air inlet of the condenser 4 is connected to air inlet pipeline two, and an air fan 10 is installed on air inlet pipeline two. The hot air outlet of the condenser 4 is connected to air inlet pipeline two, hot process gas pipeline three, hot process gas pipeline four, and Claus tail gas pipeline two, respectively. The condenser 4 is provided with a sulfuric acid outlet. The tail gas outlet of the cooling tower 5 is connected to the tail gas inlet of the desulfurization tower 6, and the desulfurization tower 6 is provided with a purified tail gas outlet.
[0038] The sulfuric acid outlet of the condenser 4 is connected to the acid intermediate tank 8 via a sulfuric acid outlet pipe. The acid intermediate tank 8 is also connected to a commercial sulfuric acid pipe. A sulfuric acid transfer pump 11 and an acid cooler 12 are installed on the commercial sulfuric acid pipe. The circulating desulfurization liquid spraying system of the desulfurization tower 6 is connected to the sulfuric acid outlet pipe and the commercial sulfuric acid pipe via a dilute sulfuric acid pipe.
[0039] This invention provides a process for producing sulfuric acid through catalytic combustion of Claus tail gas, overcoming the limitations of traditional Claus tail gas treatment processes that are "environmentally friendly but not profitable." Through a segmented, collaborative treatment architecture, it achieves complete treatment and resource utilization of Claus tail gas. Its core technologies are: first, the use of catalytic combustion technology to significantly reduce reaction energy consumption; second, the use of wet contact sulfuric acid production technology to directly produce commercial-grade concentrated sulfuric acid, converting pollutants into industrial products; and third, the end-of-pipe desulfurization unit employing hydrogen peroxide or ozone oxidation technology to ensure that tail gas emissions are far below environmental standards. Ultimately, it achieves the dual goals of "pollution control + resource recovery," providing a sustainable solution for the treatment of sulfur-containing tail gas in industries such as chemical and oil refining.
[0040] The present invention discloses a Claus tail gas catalytic combustion process for sulfuric acid production, comprising a sulfur component catalytic combustion process, a combustible component catalytic combustion process, an acid production process, and a desulfurization process. Correspondingly, the Claus tail gas catalytic combustion system of the present invention comprises a sulfur component catalytic combustion unit, a combustible component catalytic combustion unit, an acid production unit, and a desulfurization unit. The process sequence is determined based on the heat released during the combustible component catalytic combustion process to meet the preheating requirements of the Claus tail gas: when the released heat is sufficient to preheat the Claus tail gas entering the sulfur component catalytic combustion unit to the required temperature, the process flow is: sulfur component catalytic combustion process → combustible component catalytic combustion process → acid production process → desulfurization process; when the released heat is insufficient to preheat the Claus tail gas to the required temperature or barely reaches the required temperature, the process flow is: combustible component catalytic combustion process → sulfur component catalytic combustion process → acid production process → desulfurization process. The connection relationships between the various functional units are adaptively adjusted when different process flows are adopted.
[0041] The technological process and working principle of each process (functional unit) are as follows:
[0042] 1. The sulfur component catalytic combustion unit is equipped with a medium-temperature catalyst, which uses silica or alumina as a support and vanadium, iron, and other metal oxides as active components. The catalytic combustion temperature is 265–420℃, and the oxygen content in the exhaust gas after catalytic combustion is 0.5–6% Vol. The main chemical reactions that occur during the sulfur component catalytic combustion process are as follows:
[0043] 2H2S(g)+3O2(g)→2SO2(g)+2H2O(g);
[0044] Sx(g) + xO2(g) → xSO2(g).
[0045] 2. The combustible component catalytic combustion unit is equipped with a medium-temperature catalyst II, which uses alumina as a carrier and has molybdenum oxide and cobalt oxide as active components. It has sulfur poisoning resistance, the catalytic combustion temperature is 200-550℃, and the oxygen content in the exhaust gas after catalytic combustion is 0.5-8% Vol. The main chemical reactions that occur during the combustible component catalytic combustion process are as follows:
[0046] 2H₂(g) + O₂(g) → 2H₂O(g);
[0047] 2CO(g) + O2(g) → 2CO2(g).
[0048] 3. The acid production process adopts a wet contact conversion process. Under the action of a vanadium catalyst, SO2 and O2 are catalytically oxidized to SO3. The chemical reaction that occurs is as follows:
[0049] 2SO2(g) + O2(g) → 2SO3(g).
[0050] The generated SO3 was then condensed and cooled, causing it to combine with H2O in the tail gas to directly generate concentrated sulfuric acid. The chemical reaction that occurred was as follows:
[0051] SO3(g) + H2O(g) → H2SO4(l).
[0052] 4. The desulfurization process uses hydrogen peroxide oxidation or ozone oxidation to remove residual SO2 from the exhaust gas, ensuring that exhaust emissions meet environmental protection standards. The main chemical reactions involved are:
[0053] SO2(g) + H2O2(l) → H2SO4(l).
[0054] In addition to the main reaction processes described above, the functional units of this invention also exhibit the following collaborative working processes and technological effects:
[0055] (1) The heat of chemical reaction released by the catalytic combustion of combustible components is directly used to heat the Claus tail gas to be treated, so as to realize the cascade utilization of thermal energy and reduce the energy consumption of external heat source supply.
[0056] (2) The heat of chemical reaction when SO2 and O2 are catalytically oxidized to SO3 in the acid production unit is recovered by medium-pressure steam and can be used for steam in the production process or sent to generate electricity.
[0057] (3) The chemical reaction heat and condensation cooling heat released when SO3 and H2O undergo hydration reaction to generate H2SO4 in the acid production unit are recovered through heat exchange with oxygen-containing gas (such as air). The high-temperature oxygen-containing gas obtained after heat exchange is sent to the sulfur component reactor, the combustible component reactor and the SO2 converter in the acid production unit to provide the required oxygen for various catalytic combustion reactions and SO2 catalytic conversion reactions, thereby further improving energy utilization efficiency.
[0058] (4) The dilute sulfuric acid in the desulfurization tower is added to the concentrated sulfuric acid produced by the acid production unit to finally obtain commercial grade concentrated sulfuric acid with a concentration of ≥93%, and all its indicators meet the quality requirements of GB / T534 "Industrial Sulfuric Acid".
[0059] To more intuitively illustrate the present invention, the embodiments of the present invention will be further described in conjunction with the examples. The following examples are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention, including simple variations or equivalent substitutions, are all within the scope of protection of the present invention.
[0060] Example 1:
[0061] In this embodiment, as Figure 1As shown, the specific process of Claus tail gas catalytic combustion to sulfuric acid production is as follows:
[0062] Claus tail gas (temperature approximately 155°C) from the tail gas separator is first fed into the sulfur component catalytic combustion unit. In this unit, the Claus tail gas is first mixed with hot air (temperature approximately 210°C) from the acid production unit to replenish the oxygen required for the reaction, forming a cold process gas. This cold process gas then enters the process gas heat exchanger 9, where it exchanges heat with the hot process gas from the combustible component reactor 1, raising its temperature to approximately 280°C before entering the sulfur component reactor 2. The sulfur component reactor 2 is filled with a medium-temperature catalyst, using silica or alumina as a carrier and vanadium, iron, or other metal oxides as active components. Under the action of this catalyst, hydrogen sulfide and sulfur vapor in the Claus tail gas undergo catalytic combustion reactions. The main reaction equations are: 2H₂S(g) + 3O₂(g) → 2SO₂(g) + 2H₂O(g), Sx(g) + xO₂(g) → xSO₂(g). The heat of reaction released by catalytic combustion raises the temperature of the process gas to about 380°C. This hot process gas is then mixed again with hot air (about 210°C) from the acid production unit to replenish oxygen, becoming hot process gas that is then sent to the combustible component catalytic combustion unit.
[0063] In the combustible component catalytic combustion unit, the hot process gas (temperature approximately 360°C) from the sulfur component catalytic combustion unit directly enters the combustible component reactor 1. The combustible component reactor 1 is filled with a medium-temperature catalyst II, using alumina as a carrier and molybdenum oxide and cobalt oxide as active components. Under the action of this catalyst, hydrogen and carbon monoxide in the Claus tail gas undergo catalytic combustion reactions, with the main reaction formulas being: 2H₂(g) + O₂(g) → 2H₂O(g), 2CO(g) + O₂(g) → 2CO₂(g). Part of the heat released from the catalytic combustion is absorbed by the boiler water, producing saturated steam at 5.8 MPa; another part raises the temperature of the hot process gas to approximately 540°C. Subsequently, this hot process gas is mixed again with hot air (temperature approximately 210°C) from the acid production unit to replenish oxygen, and then enters the process gas heat exchanger 9 where it is cooled by the Claus tail gas to approximately 415°C before being sent to the acid production unit.
[0064] The SO2 converter 3 in the acid production unit is filled with a V2O5 catalyst bed. In the presence of water vapor, SO2 in the hot process gas is catalytically oxidized to SO3 by O2, as follows: 2SO2(g) + O2(g) → 2SO3(g). Because this conversion reaction is exothermic, to improve the SO2 / SO3 equilibrium conversion rate, inter-bed heat exchangers are installed between the catalyst beds. 5.8 MPa saturated steam generated by the sulfur production waste heat boiler is used to cool the high-temperature gas after conversion, and the recovered heat is used to generate superheated steam.
[0065] A process gas cooler is installed at the bottom of SO2 converter 3, using boiler water from steam drum 16 to cool the process gas coming out of the lower layer of SO2 converter 3 to about 285°C. Under this temperature condition, some SO3 undergoes a hydration reaction to generate H2SO4(g), as follows: SO3(g) + H2O(g) → H2SO4(g). The heat recovered in this process is used to generate saturated steam.
[0066] The process gas containing SO3 and H2SO4(g) discharged from SO2 converter 3 enters condenser 4. Condenser 4 uses cold air to indirectly cool the process gas, and strictly controls the bottom temperature of condenser 4 to be around 255℃ and the top temperature to be around 110℃. Under these temperature conditions, SO3 and H2SO4 gases are completely hydrated and condensed at the bottom of condenser 4 to form H2SO4 with a concentration of about 97%. The reaction is as follows: SO3(g) + H2O(g) → H2SO4(g), H2SO4(g) → H2SO4(l).
[0067] The sulfuric acid condensed and concentrated at the bottom of condenser 4 flows into the bottom collector and then flows by gravity into the acid intermediate tank 8 through the sulfuric acid outlet. The concentrated sulfuric acid in the acid intermediate tank 8 is pumped out by the sulfuric acid transfer pump 11 and first sent to the acid cooler 12 to be cooled to about 40°C. Most of the concentrated sulfuric acid is mixed with a small amount of dilute sulfuric acid solution sent from the desulfurization unit and then sent back to the sulfuric acid outlet pipe at the bottom of condenser 4 to mix and cool the outflowing sulfuric acid. The remaining sulfuric acid is sent out as commercial grade concentrated sulfuric acid.
[0068] The exhaust gas discharged from the top of condenser 4 is first sent to cooling tower 5 of the desulfurization unit for cooling, and then to desulfurization tower 6 for treatment. In cooling tower 5, the exhaust gas comes into countercurrent contact with the circulating spray liquid and is cooled to approximately 45°C. The heat released during this process is removed by the circulating cooling water. In desulfurization tower 6, the exhaust gas comes into countercurrent contact with the circulating hydrogen peroxide / dilute sulfuric acid mixture. The SO2 in the exhaust gas is oxidized and absorbed, and the generated sulfuric acid enters the circulating liquid. The reaction is as follows: SO2(g) + H2O2(l) → H2SO4(l). Hydrogen peroxide is continuously replenished to the circulating liquid in the desulfurization tower via a metering pump. The dilute sulfuric acid (concentration approximately 20%) generated in the reaction continuously increases in concentration in the bottom circulating tank of the tower. When the concentration reaches 30%, part of the dilute sulfuric acid is transported to the acid production unit via the desulfurization liquid circulating pump for reuse as dilution water.
[0069] The SO2-removed exhaust gas passes through the mist eliminator at the top of the desulfurization tower 6 to remove entrained mist droplets, and after meeting environmental emission standards, it is discharged through the chimney 7 in compliance with regulations.
[0070] Example 2:
[0071] In this embodiment, as Figure 2 As shown, the specific process of Claus tail gas catalytic combustion to sulfuric acid production is as follows:
[0072] Claus tail gas (temperature approximately 155°C) from the tail gas separator is first fed into the combustible component catalytic combustion unit. In this unit, the Claus tail gas is first mixed with hot air (temperature approximately 210°C) from the acid production unit to replenish the oxygen required for the reaction, forming a cold process gas. This cold process gas then enters the process gas heat exchanger 9, where it exchanges heat with the hot process gas from the combustible component reactor 1, raising its temperature to approximately 265°C before entering the combustible component reactor 1. The combustible component reactor 1 is filled with a medium-temperature catalyst II, using alumina as a carrier and molybdenum oxide and cobalt oxide as active components. Under the action of this catalyst, hydrogen and carbon monoxide in the Claus tail gas undergo catalytic combustion reactions, with the main reaction equations being: 2H₂(g) + O₂(g) → 2H₂O(g), 2CO(g) + O₂(g) → 2CO₂(g). The heat of reaction released by catalytic combustion raises the temperature of the process gas to about 450°C. This hot process gas is then mixed again with hot air (about 210°C) from the acid production unit. After oxygen is added, it becomes hot process gas again. It then enters the process gas heat exchanger 9 and is cooled to about 330°C by Claus tail gas before being sent to the sulfur component catalytic combustion unit.
[0073] In the sulfur component catalytic combustion unit, the hot process gas (temperature approximately 330°C) from the combustible component catalytic combustion unit directly enters the sulfur component reactor 2. The sulfur component reactor 2 is filled with a medium-temperature catalyst, supported by silica or alumina and containing vanadium, iron, or other metal oxides as active components. Under the action of this catalyst, hydrogen sulfide and sulfur vapor in the hot process gas undergo catalytic combustion reactions, with the main reaction equations being: 2H₂S(g) + 3O₂(g) → 2SO₂(g) + 2H₂O(g), Sx(g) + xO₂(g) → xSO₂(g). The heat released from the catalytic combustion raises the temperature of the hot process gas to approximately 435°C. Subsequently, this hot process gas is mixed again with hot air (temperature approximately 210°C) from the acid production unit to replenish oxygen, and the temperature drops to approximately 420°C before being sent to the acid production unit.
[0074] The SO2 converter 3 in the acid production unit is filled with a V2O5 catalyst bed. Inside the SO2 converter 3, SO2 in the hot process gas is catalytically oxidized to SO3 by O2 in the presence of water vapor, as follows: 2SO2(g) + O2(g) → 2SO3(g). Because this conversion reaction is exothermic, to improve the SO2 / SO3 equilibrium conversion rate, inter-bed heat exchangers are installed between the catalyst beds. 5.8 MPa saturated steam generated by the sulfur production waste heat boiler is used to cool the high-temperature gas after conversion, and the recovered heat is used to generate superheated steam.
[0075] A process gas cooler is installed at the bottom of SO2 converter 3. Boiler water from the waste heat boiler for sulfur production is used to cool the process gas coming out of the lower layer of SO2 converter to about 280°C. Under this temperature condition, some SO3 undergoes a hydration reaction to generate H2SO4(g), and the reaction is as follows: SO3(g) + H2O(g) → H2SO4(g). The heat recovered in this process is used to generate saturated steam.
[0076] The process gas containing SO3 and H2SO4(g) discharged from SO2 converter 3 enters condenser 4. Condenser 4 uses cold air to indirectly cool the process gas. The temperature at the bottom of condenser 4 is strictly controlled at about 250°C and the temperature at the top at about 110°C. Under these temperature conditions, SO3 and H2SO4(g) gas are completely hydrated and condensed at the bottom of condenser to form H2SO4 with a concentration of about 97%. The reaction is as follows: SO3(g) + H2O(g) → H2SO4(g), H2SO4(g) → H2SO4(l).
[0077] The sulfuric acid condensed and concentrated at the bottom of condenser 4 flows into the bottom collector and then flows into the acid intermediate tank 8 via the sulfuric acid outlet. The concentrated sulfuric acid in the acid intermediate tank 8 is pumped out by the sulfuric acid transfer pump 11 and first sent to the acid cooler 12 to be cooled to about 40°C. Most of the concentrated sulfuric acid is mixed with a small amount of dilute sulfuric acid solution sent from the desulfurization unit and then sent back to the sulfuric acid outlet pipe at the bottom of condenser 4 to mix and cool the outflowing sulfuric acid. The remaining sulfuric acid is sent out as commercial grade concentrated sulfuric acid.
[0078] The exhaust gas discharged from the top of condenser 4 is first sent to cooling tower 5 of the desulfurization unit for cooling, and then sent to desulfurization tower 6 for treatment. In cooling tower 5, the exhaust gas is cooled to approximately 45°C by counter-current contact with the circulating spray liquid, and the heat released during this process is removed by the circulating cooling water. In desulfurization tower 6, the exhaust gas is counter-currently contacted with the circulating hydrogen peroxide / dilute sulfuric acid mixture. The SO2 in the exhaust gas is oxidized and absorbed, and the generated sulfuric acid enters the circulating liquid, reacting as follows: SO2(g) + H2O2(l) → H2SO4(l). Hydrogen peroxide is continuously replenished to the circulating liquid in desulfurization tower 6 via a metering pump; the dilute sulfuric acid generated in the reaction (concentration approximately 20%) is continuously concentrated in the bottom circulating tank of the tower. When the concentration reaches 30%, part of the dilute sulfuric acid is transported to the acid production unit via desulfurization liquid circulation pump 15 for reuse as dilution water.
[0079] The SO2-removed exhaust gas passes through the mist eliminator at the top of the desulfurization tower 6 to remove entrained mist droplets, and after meeting environmental emission standards, it is discharged through the chimney 7 in compliance with regulations.
[0080] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A Claus tail gas catalytic combustion process for sulfuric acid production, characterized in that, This includes catalytic combustion of sulfur components, catalytic combustion of combustible components, acid production, and desulfurization. The catalytic combustion of sulfur components is carried out in a sulfur component reactor. Under the catalytic action of a mesophilic catalyst (catalyst one), the sulfur-containing components in the Claus tail gas are catalytically oxidized to SO2. The mesophilic catalyst one is a catalyst with silica or alumina as a support and vanadium and iron metal oxides as active components. The catalytic combustion temperature of the sulfur components is 265–420°C, and the oxygen content in the tail gas after catalytic combustion is 0.5–6% Vol. The catalytic combustion of combustible components is carried out in a combustible component reactor. Under the catalytic action of a mesophilic catalyst (catalyst two), the combustible components in the Claus tail gas are catalytically oxidized to H2O and CO2. The mesophilic catalyst two is a catalyst with alumina as a support and molybdenum oxide and cobalt oxide as active components. The catalytic combustion temperature of the combustible components is 200–550°C, and the oxygen content in the tail gas after catalytic combustion is 0.5–8%. Vol; The acid production process uses a wet contact method to catalytically oxidize SO2 to SO3 under the action of a vanadium catalyst. The generated SO3 gas is condensed and cooled, and then combined with water vapor in the Claus tail gas to directly generate commercial grade concentrated sulfuric acid. The desulfurization process uses hydrogen peroxide or ozone oxidation to remove residual SO2 in the tail gas after acid production, and the final tail gas meets the emission standards.
2. The Claus tail gas catalytic combustion process for sulfuric acid production according to claim 1, characterized in that, The heat released during the catalytic combustion of combustible components is used to preheat the Claus tail gas before it enters the catalytic combustion process of sulfur components. When the preheating temperature of the Claus tail gas is greater than the set temperature, the process flow is: catalytic combustion of sulfur components → catalytic combustion of combustible components → acid production → desulfurization.
3. The Claus tail gas catalytic combustion process for sulfuric acid production according to claim 1, characterized in that, The heat released during the catalytic combustion of combustible components is used to preheat the Claus tail gas before it enters the catalytic combustion process of sulfur components. When the preheating temperature of the Claus tail gas is less than or equal to the set temperature, the process flow is: catalytic combustion of combustible components → catalytic combustion of sulfur components → acid production → desulfurization.
4. The Claus tail gas catalytic combustion process for sulfuric acid production according to claim 1, characterized in that, Air or other oxygen-containing gas is used as a cold source to absorb and remove the heat of reaction and cooling in the acid production process, and then becomes hot air after heat exchange; the hot air is used to provide the oxygen required for the reaction in the catalytic combustion process of sulfur components, the catalytic combustion process of combustible components and the acid production process.
5. The Claus tail gas catalytic combustion process for sulfuric acid production according to claim 1, characterized in that, The desulfurization process removes SO2 from the Claus tail gas and generates a small amount of dilute sulfuric acid. The dilute sulfuric acid is added to the concentrated sulfuric acid produced in the acid production process to finally obtain commercial grade concentrated sulfuric acid with a concentration of ≥93%, and all indicators meet the quality requirements of GB / T 534 "Industrial Sulfuric Acid".
6. A Claus tail gas catalytic combustion system for sulfuric acid production, used to implement the Claus tail gas catalytic combustion process for sulfuric acid production as described in any one of claims 1, 2, 4, and 5; characterized in that, The system includes a process gas heat exchanger, a sulfur component reactor, a combustible component reactor, an SO2 converter, a condenser, a cooling tower, and a desulfurization tower. The sulfur component reactor is filled with a first-type medium-temperature catalyst; the combustible component reactor is filled with a second-type medium-temperature catalyst; the SO2 converter is filled with multiple layers of V2O5 catalyst beds, with inter-bed heat exchangers connected to the waste heat boiler from sulfur production; a process gas cooler is located at the bottom of the SO2 converter, and the process gas cooler and the combustible component reactor are respectively connected to a steam drum; the cooling tower is equipped with a circulating coolant spraying system, and the desulfurization tower is equipped with a circulating desulfurization liquid spraying system. The first heat exchange medium inlet of the process gas heat exchanger is connected to Claus tail gas pipeline one, and the first heat exchange medium outlet of the process gas heat exchanger is connected to the cold process gas inlet of the sulfur component reactor. The hot process gas outlet of the sulfur component reactor is connected to the hot process gas inlet of the combustible component reactor through hot process gas pipeline one, and the hot process gas outlet of the combustible component reactor is connected to the second heat exchange medium inlet of the process gas heat exchanger through hot process gas pipeline two. The second heat exchange medium outlet of the process gas heat exchanger is connected to the hot process gas inlet of the SO2 converter, and the process gas outlet of the SO2 converter is connected to the process gas inlet of the condenser. The tail gas outlet of the condenser is connected to the tail gas inlet of the cooling tower. The air inlet of the condenser is connected to air inlet pipeline one, and an air fan is installed on air inlet pipeline one. The hot air outlet of the condenser is connected to the air inlet pipeline, hot process gas pipeline one, hot process gas pipeline two, and Claus tail gas pipeline one, respectively. The condenser is provided with a sulfuric acid outlet. The tail gas outlet of the cooling tower is connected to the tail gas inlet of the desulfurization tower, and the desulfurization tower is provided with a purified tail gas outlet.
7. A Claus tail gas catalytic combustion system for sulfuric acid production, used to implement the Claus tail gas catalytic combustion process for sulfuric acid production as described in any one of claims 1, 3, 4, and 5; characterized in that, The system includes a process gas heat exchanger, a sulfur component reactor, a combustible component reactor, an SO2 converter, a condenser, a cooling tower, and a desulfurization tower. The sulfur component reactor is filled with a first-type medium-temperature catalyst; the combustible component reactor is filled with a second-type medium-temperature catalyst; the SO2 converter is filled with multiple layers of V2O5 catalyst beds, with inter-bed heat exchangers between each V2O5 catalyst bed; a process gas cooler is located at the bottom of the SO2 converter, and the inter-bed heat exchangers and the process gas cooler are respectively connected to a waste heat boiler from sulfur production; the cooling tower is equipped with a circulating coolant spraying system, and the desulfurization tower is equipped with a circulating desulfurization liquid spraying system. The first heat exchange medium inlet of the process gas heat exchanger is connected to Claus tail gas pipeline two, and the first heat exchange medium outlet is connected to the cold process gas inlet of the combustible component reactor. The hot process gas outlet of the combustible component reactor is connected to the second heat exchange medium inlet of the process gas heat exchanger via hot process gas pipeline three. The second heat exchange medium outlet of the process gas heat exchanger is connected to the hot process gas inlet of the sulfur component reactor. The hot process gas outlet of the sulfur component reactor is connected to the hot process gas inlet of the SO2 converter via hot process gas pipeline four. The process gas outlet of the SO2 converter is connected to the process gas inlet of the condenser. The tail gas outlet of the condenser is connected to the tail gas inlet of the cooling tower. The air inlet of the condenser is connected to air inlet pipeline two, and an air fan is installed on air inlet pipeline two. The hot air outlet of the condenser is connected to air inlet pipeline two, hot process gas pipeline three, hot process gas pipeline four, and Claus tail gas pipeline two, respectively. The condenser is provided with a sulfuric acid outlet. The tail gas outlet of the cooling tower is connected to the tail gas inlet of the desulfurization tower, and the desulfurization tower is provided with a purified tail gas outlet.
8. A Claus tail gas catalytic combustion system for sulfuric acid production according to claim 6 or 7, characterized in that, The sulfuric acid outlet of the condenser is connected to the intermediate acid tank via a sulfuric acid outlet pipeline. The intermediate acid tank is also connected to a commercial sulfuric acid pipeline. A sulfuric acid transfer pump and an acid cooler are installed on the commercial sulfuric acid pipeline. The circulating desulfurization liquid spraying system of the desulfurization tower is connected to the sulfuric acid outlet pipeline and the commercial sulfuric acid pipeline via a dilute sulfuric acid pipeline.