Process and system for preparing sulfuric acid through catalytic incineration of Claus tail gas

Abstract

The invention relates to a process and system for preparing sulfuric acid through catalytic incineration of Claus tail gas. The process for preparing the sulfuric acid through catalytic incineration of the Claus tail gas comprises the processes of catalytic incineration of sulfur components, catalytic incineration of combustible components, acid preparation and desulfurization. The sulfur component catalytic incineration process is used for catalytically oxidizing sulfur-containing components in the Claus tail gas into SO2; the combustible component catalytic incineration process is used for catalytically oxidizing combustible components in the Claus tail gas into H2O and CO2; the acid preparation process is used for catalytically oxidizing SO2 into SO3 under the action of a vanadium catalyst, and the generated SO3 gas is condensed and cooled and then is combined with water vapor in the Claus tail gas to directly generate commercial-grade concentrated sulfuric acid; the desulfurization process is used for removing residual SO2 in residual tail gas after acid making. The method breaks through the limitation that a traditional Claus tail gas treatment process is only environment-friendly and free of income, efficient and gradient utilization of heat energy is achieved, commercial-grade concentrated sulfuric acid is directly produced, and it is ensured that tail gas emission meets the environment-friendly standard requirement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial tail gas purification and resource utilization, and particularly relates to a Claus tail gas catalytic incineration sulfuric acid production process and system. BACKGROUND

[0002] The traditional Claus sulfur recovery process (a chemical process for converting acid gas containing hydrogen sulfide into elemental sulfur) is composed of a Claus main process and a Claus tail gas treatment process. Due to the small equilibrium constant of the Claus reaction itself, the sulfur recovery rate is usually lower than 97%, and a Claus tail gas treatment process must be matched 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 tail gas emission standard compliance.

[0003] Among the current Claus tail gas treatment technologies, the SCOT process is the most representative and widely used. The process takes deep desulfurization and recovery of Claus tail gas as the core goal, adopts a closed loop process of "hydrogen reduction + alcohol amine absorption + desorption regeneration", first reduces SO2, Sx and other sulfur oxides in the tail gas into H2S under the action of a hydrogenation catalyst, and then selectively absorbs H2S through alcohol amine solvent; the alcohol amine solution rich in H2S is released by desorption regeneration to release high-concentration H2S, which is returned to the Claus device to participate in the sulfur recovery reaction again, realizing the recycling of sulfur resources, and the purified gas at the top of the absorption tower is discharged after high-temperature incineration.

[0004] The advantages of the SCOT process are high total sulfur recovery rate, strong operation flexibility, mature and reliable technology, and no secondary pollution, but it also has obvious technical shortcomings, i.e. high construction investment and operation cost, complex process flow, dependence on external hydrogen source and fuel, high sulfur content in the exhaust gas, which cannot meet the requirements of the latest standards and must be matched with deep desulfurization to achieve standard emission.

[0005] Catalytic incineration process is a kind of tail gas purification technology based on the action of catalyst, the core principle of which is to promote the complete oxidation reaction of combustible pollutants in the tail gas under the catalytic activity of catalyst at medium and low temperature, so as to realize the dual goals of waste gas purification and resource recovery. SUMMARY

[0006] The application provides a Claus tail gas catalytic incineration sulfuric acid production process and system, and adopts catalytic incineration technology to greatly reduce reaction activation energy under the action of a catalyst, to catalytically oxidize H2S, Sx and other sulfur components in the Claus tail gas into SO2 under a medium temperature condition by introducing an oxygen-containing gas, to catalytically oxidize combustible components such as H2 and CO in the tail gas into H2O and CO2, and to fully recover reaction heat released in the reaction process to preheat the Claus tail gas to be treated, so that efficient utilization of heat energy is realized; SO2 gas generated by catalytic incineration is converted by a wet contact method, and is further catalytically oxidized into SO3 under the action of a vanadium catalyst, and then the generated SO3 gas is condensed and cooled to directly generate concentrated sulfuric acid by combining with water vapor in the tail gas; for the residual tail gas after treatment, a hydrogen peroxide oxidation method or an ozone oxidation method is adopted to remove residual SO2 therein, so that the tail gas emission meets the environmental protection standard requirements.

[0007] In order to achieve the above-mentioned purpose, the application adopts the following technical solutions: A Claus tail gas catalytic incineration sulfuric acid production process comprises a sulfur component catalytic incineration process, a combustible component catalytic incineration process, an acid production process and a desulfurization process; the sulfur component catalytic incineration process catalytically oxidizes the sulfur components in the Claus tail gas into SO2 under the catalytic action of a medium-temperature catalyst one; the combustible component catalytic incineration process catalytically oxidizes the combustible components in the Claus tail gas into H2O and CO2 under the catalytic action of a medium-temperature catalyst two; the acid production process catalytically oxidizes SO2 into SO3 under the action of a vanadium catalyst by a wet contact method, and the generated SO3 gas is combined with water vapor in the Claus tail gas after being condensed and cooled to directly generate commercial concentrated sulfuric acid; the desulfurization process removes residual SO2 in the residual tail gas after acid production by a hydrogen peroxide oxidation method or an ozone oxidation method, and the final tail gas is discharged up to the standard.

[0008] The heat released in the combustible component catalytic incineration process is used to preheat the Claus tail gas before entering the sulfur component catalytic incineration process; when the Claus tail gas preheating temperature is greater than a set temperature, the process flow is sulfur component catalytic incineration→combustible component catalytic incineration→acid production→desulfurization.

[0009] The heat released in the combustible component catalytic incineration process is used to preheat the Claus tail gas before entering the sulfur component catalytic incineration process; when the Claus tail gas preheating temperature is less than or equal to the set temperature, the process flow is combustible component catalytic incineration→sulfur component catalytic incineration→acid production→desulfurization.

[0010] The medium-temperature catalyst one is a catalyst taking silica or alumina as a carrier and taking vanadium and iron metal oxides as active components; the sulfur component catalytic incineration temperature is 265-420℃, and the oxygen content in the tail gas after catalytic incineration is 0.5-6% Vol.

[0011] The medium-temperature catalyst two is a catalyst with alumina as a carrier and molybdenum oxide and cobalt oxide as active components; the combustible component catalytic incineration temperature is 200-550℃, and the oxygen content in the tail gas after catalytic incineration is 0.5-8% Vol.

[0012] Air or other oxygen-containing gas is used as a cold source to absorb and remove the reaction heat and cooling heat in the acid production process, and then becomes hot air after heat exchange; the hot air is used for the sulfur component catalytic incineration process, the combustible component catalytic incineration process and the acid production process to provide oxygen required for reactions.

[0013] The desulfurization process removes SO2 in the Claus tail gas and generates a small amount of dilute sulfuric acid, which is mixed into the product concentrated sulfuric acid produced in the acid production process, so that the final product is commercial grade concentrated sulfuric acid with a concentration of ≥93%, and all indicators meet the quality requirements of Industrial Sulfuric Acid GB / T534.

[0014] A Claus tail gas catalytic incineration sulfuric acid production system, comprising 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 medium-temperature catalyst one; the combustible component reactor is filled with medium-temperature catalyst two; the SO2 converter is filled with multiple layers of V2O5 catalyst bed, and a bed heat exchanger is arranged between each V2O5 catalyst bed, and the bed heat exchanger is connected to a sulfur production waste heat boiler; a process gas cooler is arranged 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 provided with a circulating cooling liquid spraying system, and the desulfurization tower is provided with a circulating desulfurization liquid spraying system. The first heat exchange medium inlet of the process gas heat exchanger is connected to a Claus tail gas pipeline one, 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 a hot process gas pipeline one, 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 a 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, the process gas outlet of the SO2 converter is connected to the process gas inlet of the condenser, and 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 an air inlet pipeline one, and an air fan is arranged on the air inlet pipeline one; the hot air outlet of the condenser is respectively connected to the air inlet pipeline, the hot process gas pipeline one, the hot process gas pipeline two and the Claus tail gas pipeline one; 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.

[0015] The application discloses a Claus tail gas catalytic incineration sulfuric acid system, which comprises 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 medium-temperature catalyst I; the combustible component reactor is filled with a medium-temperature catalyst II; the SO2 converter is filled with multiple layers of V2O5 catalyst bed layers, and a bed interchanger is arranged between each V2O5 catalyst bed layer; a process gas cooler is arranged at the bottom of the SO2 converter, and the bed interchanger and the process gas cooler are connected to form a sulfuric acid waste heat boiler; the cooling tower is provided with a circulating cooling liquid spraying system, and the desulfurization tower is provided with a circulating desulfurization liquid spraying system. The first heat exchange medium inlet of the process gas heat exchanger is connected with a Claus tail gas pipeline II, the first heat exchange medium outlet is connected with the cold process gas inlet of the combustible component reactor, the hot process gas outlet of the combustible component reactor is connected with the second heat exchange medium inlet of the process gas heat exchanger through a hot process gas pipeline III, the second heat exchange medium outlet of the process gas heat exchanger is connected with the hot process gas inlet of the sulfur component reactor, the hot process gas outlet of the sulfur component reactor is connected with the hot process gas inlet of the SO2 converter through a hot process gas pipeline IV, the process gas outlet of the SO2 converter is connected with the process gas inlet of the condenser, the tail gas outlet of the condenser is connected with the tail gas inlet of the cooling tower, the air inlet of the condenser is connected with an air inlet pipeline II, and an air fan is arranged on the air inlet pipeline II; the hot air outlet of the condenser is connected with the air inlet pipeline II, the hot process gas pipeline III, the hot process gas pipeline IV and the Claus tail gas pipeline II respectively, the condenser is provided with a sulfuric acid outlet, the tail gas outlet of the cooling tower is connected with the tail gas inlet of the desulfurization tower, and the desulfurization tower is provided with a purified tail gas outlet.

[0016] The sulfuric acid outlet of the condenser is connected with an acid intermediate tank through a sulfuric acid outlet pipeline, the acid intermediate tank is additionally connected with a commercial sulfuric acid pipeline, a sulfuric acid conveying pump and an acid cooler are arranged on the commercial sulfuric acid pipeline, the circulating desulfurization liquid spraying system of the desulfurization tower is connected with the sulfuric acid outlet pipeline and the commercial sulfuric acid pipeline through a dilute sulfuric acid pipeline.

[0017] Compared with the prior art, the application has the following beneficial effects: SO2 gas generated by catalytic incineration is converted by using a wet contact method, is further catalytically oxidized into SO3 under the action of a vanadium catalyst, and then the generated SO3 gas is condensed and cooled to combine with water vapor in the tail gas to directly generate concentrated sulfuric acid; the limitation of the traditional Claus tail gas treatment process that only environmental protection is realized without income is broken, commercial concentrated sulfuric acid is directly generated, and high-value recovery of sulfur resources is realized.

[0018] For the residual tail gas after treatment, hydrogen peroxide oxidation or ozone oxidation is used to remove residual SO2, so that the tail gas emission meets the environmental protection standard requirements.

[0019] The process flow is significantly simplified, and the operation is more simple and convenient. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the process flow chart (schematic diagram of system composition) of Claus tail gas catalytic incineration for sulfuric acid in the embodiment 1 of the present application.

[0021] Figure 2 is the process flow chart (schematic diagram of system composition) of Claus tail gas catalytic incineration for sulfuric acid in the embodiment 2 of the present application.

[0022] In the figure: 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 delivery pump; 12 - acid cooler; 13 - circulating spray pump; 14 - spray liquid cooler; 15 - desulfurization liquid circulating pump; 16 - steam drum. DETAILED DESCRIPTION

[0023] The specific embodiments of the present application are further described below in conjunction with the accompanying drawings: As shown in Figure 1 , Figure 2 , the Claus tail gas catalytic incineration for sulfuric acid process described in the present application comprises a sulfur component catalytic incineration process, a combustible component catalytic incineration process, an acid production process and a desulfurization process; the sulfur component catalytic incineration process is to catalytically oxidize the sulfur-containing components in the Claus tail gas into SO2 under the catalysis of a medium-temperature catalyst one; the combustible component catalytic incineration process is to catalytically oxidize the combustible components in the Claus tail gas into H2O and CO2 under the catalysis of a medium-temperature catalyst two; the acid production process is to catalytically oxidize SO2 into SO3 under the catalysis of a vanadium catalyst by using a wet contact method, and the generated SO3 gas combines with the water vapor in the Claus tail gas after being cooled by condensation to directly generate commercial-grade concentrated sulfuric acid; the desulfurization process is to remove the residual SO2 in the residual tail gas after acid production by using a hydrogen peroxide or ozone oxidation method, and the final tail gas is discharged up to standard.

[0024] The heat released in the combustible component catalytic incineration process is used to preheat the Claus tail gas before entering the sulfur component catalytic incineration process; when the preheating temperature of the Claus tail gas > set temperature, the process flow is sulfur component catalytic incineration → combustible component catalytic incineration → acid production → desulfurization (as shown in Figure 1 ). When the preheating temperature of the Claus tail gas ≤ set temperature, the process flow is combustible component catalytic incineration → sulfur component catalytic incineration → acid production → desulfurization (as shown in Figure 2 ).

[0025] The medium-temperature catalyst one is a catalyst with silica or alumina as carrier and vanadium and iron metal oxides as active components; the sulfur component catalytic incineration temperature is 265-420℃, and the oxygen content in the tail gas after catalytic incineration is 0.5-6% Vol.

[0026] 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.

[0027] Air or other oxygen-containing gas is used as a cold source to absorb and remove the reaction heat and cooling heat 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.

[0028] 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".

[0029] 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).

[0030] 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.

[0031] 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.

[0032] The first heat exchange medium inlet of the process gas heat exchanger 9 is connected with the Claus tail gas pipeline II, the first heat exchange medium outlet is connected with the cold process gas inlet of the combustible component reactor 1, the hot process gas outlet of the combustible component reactor 1 is connected with the second heat exchange medium inlet of the process gas heat exchanger 9 through the hot process gas pipeline III, the second heat exchange medium outlet of the process gas heat exchanger 9 is connected with the hot process gas inlet of the sulfur component reactor 2, the hot process gas outlet of the sulfur component reactor 2 is connected with the hot process gas inlet of the SO2 converter 3 through the hot process gas pipeline IV, the process gas outlet of the SO2 converter 3 is connected with the process gas inlet of the condenser 4, the tail gas outlet of the condenser 4 is connected with the tail gas inlet of the cooling tower 5, the air inlet of the condenser 4 is connected with the air inlet pipeline II, and the air fan 10 is arranged on the air inlet pipeline II, the hot air outlet of the condenser 4 is connected with the air inlet pipeline II, the hot process gas pipeline III, the hot process gas pipeline IV and the Claus tail gas pipeline II respectively, the condenser 4 is provided with a sulfuric acid outlet, the tail gas outlet of the cooling tower 5 is connected with the tail gas inlet of the desulfurization tower 6, and the desulfurization tower 6 is provided with a purified tail gas outlet.

[0033] The sulfuric acid outlet of the condenser 4 is connected with the acid intermediate tank 8 through a sulfuric acid outlet pipeline, the acid intermediate tank 8 is additionally connected with a commercial sulfuric acid pipeline, the commercial sulfuric acid pipeline is provided with a sulfuric acid conveying pump 11 and an acid cooler 12, and the circulating desulfurization liquid spraying system of the desulfurization tower 6 is connected with the sulfuric acid outlet pipeline and the commercial sulfuric acid pipeline through a dilute sulfuric acid pipeline.

[0034] The application provides a process for preparing sulfuric acid by catalytic incineration of Claus tail gas, breaks the limitation of traditional Claus tail gas treatment process "only environmental protection, no income", realizes the complete treatment and resource utilization of Claus tail gas through a segmented collaborative treatment architecture. The technical core is: first, the catalytic incineration technology is adopted, which greatly reduces the reaction energy consumption; second, the wet contact method is adopted to prepare acid, which directly produces commercial grade concentrated sulfuric acid, and converts pollutants into industrial products; third, the end desulfurization unit adopts hydrogen peroxide or ozone oxidation technology, which ensures that the tail gas emission is far lower than the environmental protection standard, and finally realizes the dual goals of "pollution control + resource recovery", which provides a sustainable solution for the treatment of sulfur-containing tail gas in the chemical industry, oil refining and other industries.

[0035] The process for preparing sulfuric acid by catalytic incineration of Claus tail gas comprises a sulfur component catalytic incineration process, a combustible component catalytic incineration process, an acid preparation process and a desulfurization process. Correspondingly, the system for preparing sulfuric acid by catalytic incineration of Claus tail gas comprises a sulfur component catalytic incineration unit, a combustible component catalytic incineration unit, an acid preparation unit and a desulfurization unit. The process sequence is determined according to the heat released by the combustible component catalytic incineration process to adapt to the preheating requirement of Claus tail gas: when the released heat is sufficient to preheat the Claus tail gas entering the sulfur component catalytic incineration unit to the required temperature, the process flow is: sulfur component catalytic incineration process → combustible component catalytic incineration process → acid preparation process → desulfurization process; when the released heat is insufficient to preheat the Claus tail gas to the required temperature or just reaches the required temperature, the process flow is: combustible component catalytic incineration process → sulfur component catalytic incineration process → acid preparation process → desulfurization process. When different process flows are adopted, the connection relationship between the functional units is adaptively adjusted.

[0036] The process and principle of each process (functional unit) are as follows: 1. A medium-temperature catalyst I is arranged in the sulfur component catalytic incineration unit, which uses silicon dioxide or aluminum oxide as a carrier and vanadium, iron and other metal oxides as active components, and the catalytic incineration temperature is 265-420°C. The oxygen content in the tail gas after catalytic incineration is 0.5-6% Vol. The main chemical reactions occurring in the sulfur component catalytic incineration process are as follows: 2H2S(g) + 3O2(g) → 2SO2(g) + 2H2O(g); Sx(g) + xO2(g) → xSO2(g).

[0037] 2. A medium-temperature catalyst II is arranged in the combustible component catalytic incineration unit, which uses aluminum oxide as a carrier and molybdenum oxide and cobalt oxide as active components, and has sulfur poisoning resistance. The catalytic incineration temperature is 200-550°C. The oxygen content in the tail gas after catalytic incineration is 0.5-8% Vol. The main chemical reactions occurring in the combustible component catalytic incineration process are as follows: 2H2(g) + O2(g) → 2H2O(g); 2CO(g) + O2(g) → 2CO2(g).

[0038] 3. The acid preparation process adopts a wet contact conversion process. Under the action of vanadium catalyst, SO2 is catalytically oxidized with O2 to form SO3, and the chemical reaction is as follows: 2SO2(g) + O2(g) → 2SO3(g).

[0039] Subsequently, the generated SO3 is condensed and cooled to combine with H2O in the tail gas to directly generate concentrated sulfuric acid, and the chemical reaction is as follows: SO3(g) + H2O(g) → H2SO4(l).

[0040] 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: SO2(g) + H2O2(l) → H2SO4(l).

[0041] 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: (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.

[0042] (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.

[0043] (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.

[0044] (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".

[0045] 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.

[0046] Example 1: In this embodiment, as Figure 1 As shown, the specific process of Claus tail gas catalytic combustion to sulfuric acid production is as follows: The Claus tail gas (temperature about 155°C) from the tail gas knock-out drum is first fed into the sulfur component catalytic incineration unit. In this unit, the Claus tail gas is first mixed with hot air (temperature about 210°C) from the sulfuric acid unit to make up the oxygen required for the reaction, and then the cold process gas is formed. The cold process gas is then fed into the process gas heat exchanger 9 to exchange heat with the hot process gas from the combustible component reactor 1, and then the temperature of the cold process gas is raised to about 280°C and the cold process gas is fed into the sulfur component reactor 2. The sulfur component reactor 2 is filled with a medium temperature catalyst, which is a catalyst having a carrier of silicon dioxide or aluminum oxide and an active component of metal oxides such as vanadium and iron. Under the action of the catalyst, the hydrogen sulfide and sulfur vapor in the Claus tail gas are subjected to catalytic incineration reaction, and the main reaction formula is: 2H2S(g) + 3O2(g) → 2SO2(g) + 2H2O(g), Sx(g) + xO2(g) → xSO2(g). The reaction heat released by the catalytic incineration raises the temperature of the process gas to about 380°C, and then the hot process gas is mixed again with the hot air (temperature about 210°C) from the sulfuric acid unit to make up the oxygen, and the hot process gas is fed into the combustible component catalytic incineration unit.

[0047] In the combustible component catalytic incineration unit, the hot process gas (temperature about 360°C) from the sulfur component catalytic incineration unit is directly fed into the combustible component reactor 1. The combustible component reactor 1 is filled with a medium temperature catalyst, which is a catalyst having a carrier of aluminum oxide and an active component of molybdenum oxide and cobalt oxide. Under the action of the catalyst, the hydrogen and carbon monoxide in the Claus tail gas are subjected to catalytic incineration reaction, and the main reaction formula is: 2H2(g) + O2(g) → 2H2O(g), 2CO(g) + O2(g) → 2CO2(g). Part of the reaction heat released by the catalytic incineration is absorbed by the boiler water to produce 5.8 MPa saturated steam, and part of the reaction heat raises the temperature of the hot process gas to about 540°C. Then the hot process gas is mixed again with the hot air (temperature about 210°C) from the sulfuric acid unit to make up the oxygen, and the hot process gas is cooled to about 415°C in the process gas heat exchanger 9 by the Claus tail gas, and then the hot process gas is fed into the sulfuric acid unit.

[0048] The SO2 converter 3 in the sulfuric acid unit is filled with a V2O5 catalyst bed, and the SO2 in the hot process gas is catalytically oxidized to SO3 in the presence of water vapor, and the reaction is as follows: 2SO2(g) + O2(g) → 2SO3(g). Since the conversion reaction is an exothermic reaction, in order to improve the equilibrium conversion rate of SO2 / SO3, a bed-to-bed heat exchanger is arranged between each catalyst bed, and 5.8 MPa saturated steam generated by the sulfur production waste heat boiler is used to cool the converted high-temperature gas, and the recovered heat is used to generate superheated steam.

[0049] A process gas cooler is installed at the lower section of the SO2 converter 3 to cool the process gas coming out of the lower section of the SO2 converter 3 to about 285°C using boiler water in the steam drum 16; at this temperature, part of the SO3 is hydrated to form H2SO4(g) according to the reaction: SO3(g) + H2O(g) → H2SO4(g), and the heat recovered from this process is used to generate saturated steam.

[0050] The process gas containing SO3 and H2SO4(g) coming out of the SO2 converter 3 enters the condenser 4; the condenser 4 uses cold air to indirectly cool the process gas, and the temperature at the bottom of the condenser 4 is strictly controlled to be about 255°C and the temperature at the top of the condenser 4 is about 110°C; at this temperature, the SO3 and H2SO4(g) are completely hydrated and condensed at the bottom of the condenser 4 to form about 97% concentrated H2SO4 according to the reactions: SO3(g) + H2O(g) → H2SO4(g), and H2SO4(g) → H2SO4(l).

[0051] The concentrated H2SO4 formed at the bottom of the condenser 4 flows into the bottom collector and is discharged into the intermediate tank 8 through the H2SO4 outlet; the concentrated H2SO4 in the intermediate tank 8 is pumped out by the H2SO4 delivery pump 11 and is first cooled to about 40°C in the H2SO4 cooler 12; most of the concentrated H2SO4 is mixed with a small amount of dilute H2SO4 solution delivered by the desulfurization unit and is then returned to the H2SO4 outlet pipeline at the bottom of the condenser 4 to cool the discharged H2SO4, and the remaining H2SO4 is discharged as commercial concentrated H2SO4.

[0052] The tail gas discharged from the top of the condenser 4 is first sent to the cooling tower 5 of the desulfurization unit for cooling, and then is sent to the desulfurization tower 6 for treatment; in the cooling tower 5, the tail gas is countercurrently contacted with the circulating spray liquid and is cooled to about 45°C, and the heat released in this process is removed by circulating cooling water; in the desulfurization tower 6, the tail gas is countercurrently contacted with the circulating spray liquid of hydrogen peroxide / dilute sulfuric acid mixture, and the SO2 in the tail gas is oxidized and absorbed to form H2SO4, which enters the circulating liquid, according to the reaction: SO2(g) + H2O2(l) → H2SO4(l). Hydrogen peroxide is continuously supplemented to the desulfurization tower circulating liquid by a metering pump; the dilute sulfuric acid (about 20% concentration) generated by the reaction is continuously concentrated in the tower bottom circulating tank, and when the concentration reaches 30%, part of the dilute sulfuric acid is delivered to the acid making unit by the desulfurization liquid circulating pump for reuse as dilution water.

[0053] The SO2-removed tail gas is removed from the entrained mist by a mist eliminator at the upper part of the desulfurization tower 6, and is discharged through the chimney 7 to meet the environmental protection emission standard.

[0054] Example 2: In this example, as shown in Figure 2 the Claus tail gas catalytic incineration process for producing sulfuric acid is as follows: The Claus tail gas (temperature about 155°C) from the tail gas knock-out drum is first sent to the combustible component catalytic incineration unit. In this unit, the Claus tail gas is first mixed with hot air (temperature about 210°C) from the acid making unit to form the cold process gas after supplementing oxygen required for the reaction; the cold process gas is then sent to the process gas heat exchanger 9 to exchange heat with the hot process gas from the combustible component reactor 1, and is heated to about 265°C before entering the combustible component reactor 1. The combustible component reactor 1 is filled with a medium temperature type catalyst two with alumina as the carrier and molybdenum oxide and cobalt oxide as the active components. Under the action of this catalyst, catalytic incineration reaction of hydrogen and carbon monoxide in the Claus tail gas occurs, and the main reaction formula is: 2H2(g) + O2(g) → 2H2O(g), 2CO(g) + O2(g) → 2CO2(g). The reaction heat released by the catalytic incineration makes the temperature of the process gas rise to about 450°C, and then the hot process gas is mixed again with hot air (temperature about 210°C) from the acid making unit to form the hot process gas after supplementing oxygen, and then enters the process gas heat exchanger 9 to be cooled to about 330°C by the Claus tail gas, and is sent to the sulfur component catalytic incineration unit.

[0055] In the sulfur component catalytic incineration unit, the hot process gas (temperature about 330°C) from the combustible component catalytic incineration unit is directly sent to the sulfur component reactor 2. The sulfur component reactor 2 is filled with a medium temperature type catalyst one with silica or alumina as the carrier and vanadium, iron and other metal oxides as the active components. Under the action of this catalyst, catalytic incineration reaction of hydrogen sulfide and sulfur vapor in the hot process gas occurs, and the main reaction formula is: 2H2S(g) + 3O2(g) → 2SO2(g) + 2H2O(g), Sx(g) + xO2(g) → xSO2(g). The reaction heat released by the catalytic incineration makes the temperature of the hot process gas rise to about 435°C, and then the hot process gas is mixed again with hot air (temperature about 210°C) from the acid making unit to supplement oxygen, and the temperature drops to about 420°C, and is sent to the acid making unit.

[0056] The SO2 converter 3 in the acid making unit is filled with a V2O5 catalyst bed. In the SO2 converter 3, SO2 in the hot process gas is catalytically oxidized to SO3 in the presence of water vapor, and the reaction is as follows: 2SO2(g) + O2(g) → 2SO3(g). Since this conversion reaction is an exothermic reaction, in order to improve the equilibrium conversion rate of SO2 / SO3, bed-to-bed heat exchangers are arranged between each catalyst bed, and 5.8 MPa saturated steam generated by the sulfur production waste heat boiler is used to cool the converted high temperature gas, and the recovered heat is used to generate superheated steam.

[0057] A process gas cooler is installed at the lowermost section of the SO2 converter 3, and the process gas from the lower section of the SO2 converter is cooled to about 280°C by boiler water from the sulfur-making waste heat boiler; at this temperature, part of the SO3 is hydrated to form H2SO4(g), and the reaction is as follows: SO3(g) + H2SO4(g) → H2SO4(g), and the heat recovered in this process is used to generate saturated steam.

[0058] The process gas containing SO3 and H2SO4(g) discharged from the SO2 converter 3 enters the condenser 4; the condenser 4 uses cold air to indirectly cool the process gas, and the temperature at the bottom of the condenser 4 is strictly controlled at about 250°C, and the temperature at the top is about 110°C; at this temperature, the SO3 and H2SO4(g) gas is completely hydrated and condensed at the bottom of the condenser to form about 97% concentrated H2SO4, and the reaction is as follows: SO3(g) + H2SO4(g) → H2SO4(g), H2SO4(g) → H2SO4(l).

[0059] The concentrated sulfuric acid formed by condensation at the lower part of the condenser 4 flows into the bottom collector and is discharged into the intermediate acid tank 8 through the sulfuric acid outlet; the concentrated sulfuric acid in the intermediate acid tank 8 is pumped out by the sulfuric acid delivery pump 11 and is first cooled to about 40°C in the acid cooler 12, and then mixed with a small amount of dilute sulfuric acid solution from the desulfurization unit and returned to the sulfuric acid outlet pipeline at the bottom of the condenser 4 for mixed cooling, and the remaining sulfuric acid is discharged as commercial grade concentrated sulfuric acid.

[0060] The tail gas discharged from the top of the condenser 4 is first sent to the cooling tower 5 of the desulfurization unit for cooling, and then sent to the desulfurization tower 6 for treatment. In the cooling tower 5, the tail gas is cooled to about 45°C by countercurrent contact with the circulating spray liquid, and the heat released in this process is removed by circulating cooling water. In the desulfurization tower 6, the tail gas is countercurrently contacted with the circulating spray of hydrogen peroxide / dilute sulfuric acid mixture, and the SO2 in the tail gas is oxidized and absorbed to form sulfuric acid into the circulating liquid, and the reaction is as follows: SO2(g) + H2O2(l) → H2SO4(l). Hydrogen peroxide is continuously supplemented to the circulating liquid in the desulfurization tower 6 by a metering pump; the dilute sulfuric acid (about 20% concentration) generated by the reaction is continuously concentrated in the circulating tank at the bottom of the tower, and when the concentration reaches 30%, part of the dilute sulfuric acid is pumped to the acid-making unit by the desulfurization liquid circulating pump 15 for reuse as dilution water.

[0061] The SO2-removed tail gas passes through the mist eliminator at the upper part of the desulfurization tower 6 to remove entrained mist droplets, and is discharged through the chimney 7 to meet the environmental protection emission standard.

[0062] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical solution and inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

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 sulfuric acid production system, used to implement the Claus tail gas catalytic combustion sulfuric acid production process as described in 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 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.

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