Method for preparing sulfuric acid from hydrogen sulfide by wet process

Abstract

The invention relates to the field of environment-friendly sulfuric acid preparation, and discloses a method for preparing sulfuric acid from hydrogen sulfide by a wet process. The method comprises the following steps: S1, combusting acidic gas containing hydrogen sulfide to obtain process gas rich in SO2; s2, performing multi-stage catalysis on the process gas rich in SO2 to obtain process gas rich in SO3; s3, condensing the process gas rich in SO3 to obtain first sulfuric acid and condensed gas; and S4, contacting the condensed gas with noble metal modified activated carbon to obtain second sulfuric acid and tail gas. According to the method, multi-stage catalysis and precious metal modified activated carbon catalysis are combined, so that the content of SO2 and nitrogen oxide in tail gas can be reduced while the high SO2 total conversion rate is ensured. And meanwhile, the generated second sulfuric acid is returned to the step S3 and sprayed from the top of the condenser, so that the generation of acidic wastewater can be reduced.

Description

Technical Field

[0001] The invention relates to the field of environmentally friendly sulfuric acid production, and in particular to a method for preparing sulfuric acid using wet hydrogen sulfide. Background Art

[0002] WSA sulfuric acid units are mostly distributed in oil refining, nonferrous metallurgy, fertilizer, viscose fiber, coal coking, coal chemical industry and other industries, and are used for the treatment of low-sulfur gas. This process does not require washing and drying. In the presence of water vapor, sulfur dioxide is catalytically converted into sulfur trioxide and directly condensed into acid. It has the advantages of simple process, high sulfur recovery rate, high energy efficiency, no wastewater generation, large operational flexibility, low operating cost, and no pollution to the environment.

[0003] The wet sulfuric acid production process has developed rapidly in my country, mainly as an environmental protection device for treating acid gas from desulfurization units. Generally, the device is small in scale and is used to directly produce acid from sulfuric acid-containing gas in production to obtain commercial grade concentrated sulfuric acid, and the tail gas meets the emission standards.

[0004] In the existing traditional wet acid gas acid-making unit, the one-conversion-one-cooling process has a maximum of three catalyst beds in the converter, considering the bed pressure drop problem. In order to improve the overall SO2 conversion rate, a two-conversion-two-cooling process can be used, but it increases the equipment cost.

[0005] Currently, the method for preparing sulfuric acid with wet hydrogen sulfide is simple, but the conversion rate of sulfur dioxide in the existing technology is low and the sulfur dioxide content in the exhaust gas finally discharged is high, which is not in line with the concept of environmental protection. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems of low sulfur dioxide conversion rate and high sulfur dioxide content in the exhaust gas finally discharged in the prior art, and to provide a method for preparing sulfuric acid with wet hydrogen sulfide. The method combines multi-stage catalysis with precious metal modified activated carbon catalysis, thereby ensuring a high total SO2 conversion rate while reducing the content of SO2 and nitrogen oxides in the exhaust gas.

[0007] In order to achieve the above object, the present invention provides a method for preparing sulfuric acid by wet hydrogen sulfide, characterized in that it comprises:

[0008] S1, burning the acidic gas containing hydrogen sulfide to obtain a process gas rich in SO2;

[0009] S2, subjecting the SO2-rich process gas to multi-stage catalysis to obtain SO3-rich process gas;

[0010] S3, condensing the SO3-rich process gas to obtain first sulfuric acid and condensed gas;

[0011] S4. Contacting the condensed gas with activated carbon modified with precious metals to obtain a second sulfuric acid and tail gas.

[0012] Through the above technical scheme, the method for preparing sulfuric acid by wet hydrogen sulfide provided by the present invention achieves the following beneficial effects:

[0013] (1) This method combines multi-stage catalysis with precious metal-modified activated carbon catalysis to reduce the content of SO2, nitrogen oxides and acid mist in the exhaust gas while ensuring a high total SO2 conversion rate.

[0014] (2) In this method, the generated second sulfuric acid is returned to step S3 and sprayed from the top of the condenser, which can reduce the generation of acidic wastewater. DETAILED DESCRIPTION

[0015] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0016] The present invention provides a method for preparing sulfuric acid by wet hydrogen sulfide, comprising:

[0017] S1, burning the acidic gas containing hydrogen sulfide to obtain a process gas rich in SO2;

[0018] S2, subjecting the SO2-rich process gas to multi-stage catalysis to obtain SO3-rich process gas;

[0019] S3, condensing the SO3-rich process gas to obtain first sulfuric acid and condensed gas;

[0020] S4. Contacting the condensed gas with activated carbon modified with precious metals to obtain a second sulfuric acid and tail gas.

[0021] In the present invention, the method combines multi-stage catalysis with precious metal modified activated carbon catalysis, thereby ensuring a high total SO2 conversion rate while reducing the content of SO2 and nitrogen oxides in the tail gas.

[0022] In the present invention, the method further comprises: before the multi-stage catalysis, heat exchange is performed on the SO2-rich process gas, for example, heat exchange can be performed by a high-temperature waste heat boiler.

[0023] In the present invention, the method further comprises: before condensing the SO 3 -rich process gas, heat exchanging the SO 3 -rich process gas, for example, heat exchanging the process gas through a medium-temperature waste heat boiler.

[0024] In the present invention, in step S1, the combustion further includes introducing a certain amount of hot air to adjust the temperature during combustion. When the combustion temperature is lower than 900°C, a certain amount of fuel gas can be introduced to ensure the smooth progress of the combustion reaction. There is no special requirement for the amount of the fuel gas, as long as the combustion temperature meets 900-1100°C. For example, the content of the fuel gas is 1-5vol% of the total gas amount in the entire combustion system.

[0025] In the present invention, the fuel gas is selected from one or more of methane, ethane or propane.

[0026] In the present invention, in step S1, the combustion may be a conventional combustion method in the art, such as introducing air or oxygen. There is no particular requirement for the amount of air or oxygen introduced, as long as the combustion temperature meets 900-1100°C.

[0027] In the present invention, the combustion of the acidic gas containing hydrogen sulfide is a conventional combustion method in the art, and the amount of the acidic gas containing hydrogen sulfide, the amount of air and the amount of fuel gas used are not limited, as long as the SO2 content in the process gas after combustion meets 4.1-4.5 vol%.

[0028] In the present invention, the gas flow rate of the SO2-rich process gas after heat exchange when entering the first stage of the multi-stage catalysis is 15000-25000Nm 3 / h.

[0029] According to the present invention, in the noble metal-modified activated carbon, the noble metal is selected from at least one of platinum, palladium or rhodium.

[0030] In the present invention, the noble metal is selected from the above types, which can improve the catalytic efficiency and ensure a high overall conversion rate of SO2.

[0031] In the present invention, the total conversion rate of SO2 refers to the percentage of SO2 converted into SO3 in the system to the total amount of SO2 entering the system.

[0032] According to the present invention, based on the total weight of the noble metal-modified activated carbon, the loading amount of the noble metal is 0.5-1.5 wt‰, preferably 1-1.5 wt‰.

[0033] According to the present invention, based on the total volume of the condensed gas, the amount of the noble metal-modified activated carbon is 50 Nm 3 -100Nm 3 .

[0034] In the present invention, the amount of the noble metal-modified activated carbon meets the above range, which can improve the total conversion rate of SO2 while ensuring the cost.

[0035] Furthermore, based on the total volume of the condensed gas, the amount of the noble metal-modified activated carbon is 55 m 3 -65m 3 .

[0036] According to the present invention, the multi-stage catalysis comprises at least three stages.

[0037] In the present invention, the multi-stage catalysis refers to a catalytic reaction carried out in a device containing multiple catalyst beds, for example, a three-stage catalyst contains three catalyst beds.

[0038] According to the present invention, in the multi-stage catalysis, the process gas generated by each stage of catalysis is heat exchanged before entering the next stage of catalysis.

[0039] In the present invention, the process gas is heat exchanged through a heat exchanger, and the heat exchange medium may utilize the first steam drum generated in the high-temperature waste heat boiler and / or the second steam drum generated in the medium-temperature waste heat boiler.

[0040] In the present invention, the method further comprises removing nitrogen oxides from the process gas after heat exchange in the high-temperature waste heat boiler. The conditions for removing nitrogen oxides can be conventional methods and conditions in the art, such as using a denitration catalyst for removal.

[0041] According to one embodiment of the present invention, the multi-stage catalysis includes primary catalysis, secondary catalysis and tertiary catalysis, wherein the primary catalysis and the secondary catalysis are carried out in the presence of a vanadium catalyst, and the tertiary catalysis is carried out in the presence of a platinum catalyst.

[0042] In the present invention, the primary catalysis and the secondary catalysis are carried out in the presence of a vanadium catalyst, and the tertiary catalysis is carried out in the presence of a platinum catalyst, which can reduce the bed pressure drop, improve the catalytic efficiency, and further improve the total conversion rate of SO2.

[0043] In the present invention, the platinum catalyst is a honeycomb rectangular catalyst with 55-70 holes and a size (length, width, height) of 150×150×600 mm and / or 150×150×300 mm.

[0044] According to the present invention, the inlet temperature of the first-stage catalyst is 380-440°C, and the outlet temperature of the first-stage catalyst is 490-560°C.

[0045] According to the present invention, the inlet temperature of the secondary catalysis is 400-430°C, and the outlet temperature of the secondary catalysis is 450-480°C.

[0046] According to the present invention, the inlet temperature of the three-stage catalyst is 380-400°C, and the outlet temperature of the three-stage catalyst is 382-405°C.

[0047] According to one embodiment of the present invention, the multi-stage catalysis includes primary catalysis, secondary catalysis, tertiary catalysis and quaternary catalysis, the primary catalysis and the secondary catalysis are carried out in the presence of a vanadium catalyst, and the tertiary catalysis and the quaternary catalysis are carried out in the presence of a platinum catalyst.

[0048] In the present invention, the primary catalysis and the secondary catalysis are carried out in the presence of a vanadium catalyst, and the tertiary catalysis and the quaternary catalysis are carried out in the presence of a platinum catalyst, which can reduce the bed pressure drop, improve the catalytic efficiency, and further improve the total conversion rate of SO2.

[0049] According to the present invention, the inlet temperature of the first-stage catalyst is 380-440°C, and the outlet temperature of the first-stage catalyst is 490-560°C.

[0050] According to the present invention, the inlet temperature of the secondary catalysis is 400-430°C, and the outlet temperature of the secondary catalysis is 450-480°C.

[0051] According to the present invention, the inlet temperature of the three-stage catalyst is 380-400°C, and the outlet temperature of the three-stage catalyst is 382-405°C.

[0052] According to the present invention, the inlet temperature of the four-stage catalyst is 390-400°C, and the outlet temperature of the four-stage catalyst is 391-401°C.

[0053] According to the present invention, the packing factor of the vanadium catalyst is 500-1200 L / (t*d), and the packing factor of the platinum catalyst is 5-10 L / (t*d).

[0054] In the present invention, the packing coefficients of the vanadium catalyst and the platinum catalyst meet the above range, which can reduce the bed resistance to the maximum extent and improve the total conversion rate of SO2.

[0055] Furthermore, the packing factor of the vanadium catalyst is 550-900 L / (t*d), and the packing factor of the platinum catalyst is 6-8 L / (t*d).

[0056] According to the present invention, the platinum catalyst comprises a porous carrier and a platinum active component supported on the porous carrier.

[0057] In the present invention, the platinum active component is a single substance of metallic platinum.

[0058] According to the present invention, based on the total weight of the platinum catalyst, the content of the metal platinum is 0.5-2 wt‰, preferably 0.5-1 wt‰.

[0059] According to the present invention, the porous carrier is selected from at least one of titanium dioxide, diatomaceous earth, montmorillonite and attapulgite.

[0060] According to one embodiment of the present invention, the content of H2S in the acidic gas containing hydrogen sulfide is 30-90 vol%.

[0061] According to the present invention, the acidic gas containing hydrogen sulfide also contains 5-20 vol% CO2, 1-2 vol% C2H6, and 2-4 vol% H2O.

[0062] According to the present invention, the SO2 content in the SO2-rich process gas is 1.5-6.5 vol%.

[0063] According to the present invention, in step S1, the combustion temperature is 900-1100°C.

[0064] According to the present invention, in order to obtain a further better effect, the method further comprises: before the SO2-rich process gas is subjected to multi-stage catalysis, the temperature of the SO2-rich process gas is adjusted to 380-440°C.

[0065] According to the present invention, the condensed gas contains 100-500 ppm of SO2.

[0066] According to the present invention, the second sulfuric acid is returned to step S3 for recycling.

[0067] According to the present invention, in step S3, the condensation temperature is 250-260°C.

[0068] According to the present invention, in step S4, the contact conditions include: contact temperature of 30-80° C., and contact time of 0.1-0.5 h.

[0069] In the present invention, the contact conditions satisfy the above range, which can further improve the total conversion rate of SO2 and reduce the content of SO2 in the tail gas.

[0070] According to the present invention, the content of SO2 in the tail gas is ≤10mg / Nm 3 , acid mist content ≤ 0.03g / Nm 3 , nitrogen oxide content ≤30mg / Nm 3 .

[0071] Furthermore, the content of SO2 in the tail gas is ≤5mg / Nm 3 , acid mist content ≤ 0.02g / Nm 3 , nitrogen oxide content ≤20mg / Nm 3 .

[0072] According to a particularly preferred embodiment of the present invention, the method comprises:

[0073] S1. The acidic gas containing hydrogen sulfide generated by the combustion of the upstream medium-sulfur coal is mixed with the cold air introduced by the external fan and the hot air at the bottom of the condenser for combustion. When the combustion temperature is not enough, the fuel gas is introduced for supplementation. The combustion temperature is 1000-1100°C to obtain a process gas rich in SO2, and the SO2 content in the process gas meets 4.1-4.5 vol%;

[0074] S2, the SO2-rich process gas is heat exchanged in a high-temperature waste heat boiler, and then enters a four-stage converter for four-stage catalysis after removing nitrogen oxides. The inlet temperature of the first-stage catalysis is 390-410°C, and the inlet gas flow rate is 8050-15828Nm 3 / h, the inlet SO2 concentration is 1.98-5.05vol%. The outlet temperature of the first-stage catalytic converter is 440-519°C, the inlet temperature of the second-stage catalytic converter is 390-410°C, and the outlet temperature is 395-422°C. The catalysts of the first-stage catalytic converter and the second-stage catalytic converter are vanadium catalysts, and the loading factor is 710-920L / (t*d). The inlet temperature of the third-stage catalytic converter is 390-400°C, and the outlet temperature is 393-409°C. The inlet temperature of the fourth-stage catalytic converter is 390-400°C, and the outlet temperature is 392-400°C. The catalysts of the third-stage catalytic converter and the fourth-stage catalytic converter are platinum catalysts, and the loading factor is 5-10L / (t*d), and a process gas rich in SO3 is obtained;

[0075] S3, the SO3-rich process gas enters a condenser and is condensed at 250-260° C. to obtain first sulfuric acid and condensed gas, wherein the SO3-rich process gas has an inlet temperature of 290° C. entering the condenser and an outlet condenser temperature of 90° C.;

[0076] S4, contacting the condensed gas with the activated carbon modified with the precious metal for 0.1-0.5h at 30-80°C, spraying the generated SO3 with deionized water to obtain a second sulfuric acid and tail gas, returning the second sulfuric acid to step S3 and mixing it with the first sulfuric acid, wherein the loading amount of the precious metal is 0.5-2wt‰ based on the total weight of the activated carbon modified with the precious metal, and the amount of the activated carbon modified with the precious metal is 50Nm 3 -100Nm 3 .

[0077] The present invention will be described in detail below through examples.

[0078] In the following examples, the total conversion rate of SO2 is calculated by the percentage method of SO2 converted into SO3 in the system to the total amount of SO2 entering the system;

[0079] The content of SO2, nitrogen oxides and acid mist in the tail gas is measured by online instrument analysis method;

[0080] The unit of catalyst loading coefficient is L / t*d, where L is the catalyst loading, t is the ton of acid produced, and d is day. The loading coefficient indicates the catalyst loading corresponding to the ton of acid produced by the device per day.

[0081] In the following examples, the composition of the acidic gas containing hydrogen sulfide is: 85 vol% H2S, 10 vol% CO2, 2 vol% C2H6, and 3 vol% H2O.

[0082] In the following examples, unless otherwise specified, the carrier of the platinum catalyst is titanium dioxide.

[0083] Example 1

[0084] S1. The acidic gas containing hydrogen sulfide generated by the combustion of the upstream medium-sulfur coal is introduced into the incinerator, mixed with the cold air from the outside and the hot air from the bottom of the condenser for combustion at a combustion temperature of 1000°C to obtain a process gas rich in SO2, wherein the SO2 content is 4.1 vol%;

[0085] S2, the SO2-rich process gas is heat exchanged in a high-temperature waste heat boiler, and then the nitrogen oxides are removed and then enter the three-stage converter for three-stage catalysis. The inlet temperature of the first-stage catalysis is 410°C, and the inlet gas flow rate is 20503Nm 3 / h, the inlet SO2 concentration is 4.1vol%. The outlet temperature of the first-stage catalyst is 500℃, the inlet temperature of the second-stage catalyst is 420℃, the outlet temperature is 425℃, the catalysts of the first-stage catalyst and the second-stage catalyst are vanadium catalysts, and the filling coefficient is 780L / (t*d). The inlet temperature of the third-stage catalyst is 390℃, the outlet temperature is 392℃, the catalyst of the third-stage catalyst is a platinum catalyst, and the filling coefficient is 6L / (t*d), and a process gas rich in SO3 is obtained;

[0086] S3, the SO3-rich process gas enters a condenser and is condensed at 255° C. to obtain first sulfuric acid and condensed gas, wherein the SO3-rich process gas has an inlet temperature of 290° C. entering the condenser and an outlet condenser temperature of 90° C.;

[0087] S4, contacting the condensed gas with activated carbon modified with platinum metal at 40°C for 0.3h, spraying the generated SO3 with deionized water to obtain a second sulfuric acid and tail gas, returning the second sulfuric acid to step S3 and mixing it with the first sulfuric acid, wherein the loading amount of the noble metal is 0.6wt‰ based on the total weight of the activated carbon modified with the noble metal, and the amount of the activated carbon modified with the noble metal is 60Nm 3 .

[0088] Among them, the total conversion rate of SO2 is 99.3%, and the SO2 content in the tail gas is 5mg / Nm3 , the content of nitrogen oxides is 30mg / Nm 3 , acid mist content is 0.03g / Nm 3 .

[0089] Example 2

[0090] S1, same as in Example 1;

[0091] S2, the SO2-rich process gas is heat exchanged in a high-temperature waste heat boiler, and then enters a four-stage converter for four-stage catalysis after removing nitrogen oxides. The inlet temperature of the first-stage catalysis is 410°C, and the inlet gas flow rate is 8167Nm 3 / h, the inlet SO2 concentration is 2.01vol%. The outlet temperature of the first catalytic converter is 463℃, the inlet temperature of the second catalytic converter is 410℃, the outlet temperature is 415℃, the catalysts of the first and second catalytic converters are vanadium catalysts, the loading factor is 900L / (t*d), the inlet temperature of the third catalytic converter is 390℃, the outlet temperature is 392℃, the inlet temperature of the fourth catalytic converter is 390℃, the outlet temperature is 391℃, the catalysts of the third and fourth catalytic converters are platinum catalysts, the loading factor is 5L / (t*d), and a process gas rich in SO3 is obtained;

[0092] S3, the SO3-rich process gas enters a condenser and is condensed at 260° C. to obtain first sulfuric acid and condensed gas, wherein the SO3-rich process gas has an inlet temperature of 288° C. when entering the condenser and an outlet temperature of 85° C.;

[0093] S4, contacting the condensed gas with activated carbon modified with platinum or rhodium metals for 0.1 h at 30°C, spraying the generated SO3 with deionized water to obtain a second sulfuric acid and tail gas, returning the second sulfuric acid to step S3 and mixing it with the first sulfuric acid, wherein the loading amount of the noble metal is 0.6 wt‰ based on the total weight of the noble metal-modified activated carbon, and the amount of the noble metal-modified activated carbon is 60 Nm 3 .

[0094] Among them, the total conversion rate of SO2 is 99.4%, and the SO2 content in the tail gas is 3mg / Nm 3 , the content of nitrogen oxides is 29mg / Nm 3 , acid mist content is 0.029g / Nm 3 .

[0095] Example 3

[0096] S1, same as in Example 1;

[0097] S2, the SO2-rich process gas is heat exchanged in a high-temperature waste heat boiler, and then the nitrogen oxides are removed, and then enters the three-stage converter for three-stage catalysis. The inlet temperature of the first-stage catalysis is 410°C, and the inlet gas flow rate is 20590Nm 3 / h, the inlet SO2 concentration is 3.72vol%. The outlet temperature of the first-stage catalyst is 499℃, the inlet temperature of the second-stage catalyst is 420℃, the outlet temperature is 425℃, the catalysts of the first-stage catalyst and the second-stage catalyst are vanadium catalysts, and the filling coefficient is 780L / (t*d). The inlet temperature of the third-stage catalyst is 390℃, the outlet temperature is 392℃, the catalyst of the third-stage catalyst is platinum catalyst, and the filling coefficient is 6L / (t*d), and a process gas rich in SO3 is obtained;

[0098] S3, the SO3-rich process gas enters a condenser and is condensed at 250° C. to obtain first sulfuric acid and condensed gas, wherein the SO3-rich process gas has an inlet temperature of 290° C. entering the condenser and an outlet condenser temperature of 90° C.;

[0099] S4, contacting the condensed gas with palladium metal-modified activated carbon at 75°C for 0.2h, spraying the generated SO3 with deionized water to obtain a second sulfuric acid and tail gas, returning the second sulfuric acid to step S3 and mixing it with the first sulfuric acid, wherein the loading amount of the noble metal is 0.55wt‰ based on the total weight of the noble metal-modified activated carbon, and the amount of the noble metal-modified activated carbon is 70Nm 3 .

[0100] Among them, the total conversion rate of SO2 is 99.1%, and the SO2 content in the tail gas is 5mg / Nm 3 , acid mist content is 0.025g / Nm 3 , the content of nitrogen oxides is 28mg / Nm 3 .

[0101] Example 4

[0102] S1. The acidic gas containing hydrogen sulfide generated by the combustion of the upstream medium-sulfur coal is introduced into the incinerator, mixed with the cold air from the outside and the hot air from the bottom of the condenser for combustion at a combustion temperature of 1100°C to obtain a process gas rich in SO2, wherein the SO2 content is 4.5 vol%;

[0103] S2, the SO2-rich process gas is heat exchanged in a high-temperature waste heat boiler, and then enters a four-stage converter for four-stage catalysis after removing nitrogen oxides. The inlet temperature of the first-stage catalysis is 430°C, and the inlet gas flow rate is 20802Nm 3 / h, the inlet SO2 concentration is 5.1vol%. The outlet temperature of the first catalytic converter is 541°C, the inlet temperature of the second catalytic converter is 430°C, the outlet temperature is 455°C, the catalysts of the first and second catalytic converters are vanadium catalysts, and the loading factor is 700L / (t*d). The inlet temperature of the third catalytic converter is 400°C, the outlet temperature is 410°C, the inlet temperature of the fourth catalytic converter is 400°C, the outlet temperature is 405°C, the catalysts of the third and fourth catalytic converters are platinum catalysts, and the loading factor is 5L / (t*d), and a process gas rich in SO3 is obtained;

[0104] S3, the SO3-rich process gas enters a condenser and is condensed at 250° C. to obtain first sulfuric acid and condensed gas, wherein the SO3-rich process gas has an inlet temperature of 295° C. when entering the condenser and an outlet temperature of 90° C.;

[0105] S4, contacting the condensed gas with activated carbon modified with platinum metal at 70°C for 0.1h, spraying the generated SO3 with deionized water to obtain a second sulfuric acid and tail gas, returning the second sulfuric acid to step S3 and mixing it with the first sulfuric acid, wherein the loading amount of the noble metal is 0.5‰ based on the total weight of the activated carbon modified with the noble metal, and the amount of the activated carbon modified with the noble metal is 65Nm 3 .

[0106] Among them, the total conversion rate of SO2 is 99.5%, and the SO2 content in the tail gas is 8mg / Nm 3 , the content of nitrogen oxides is 30mg / Nm 3 , acid mist content is 0.03g / Nm 3 .

[0107] Example 5

[0108] S1, same as in Example 1;

[0109] S2, the SO2-rich process gas is heat exchanged in a high-temperature waste heat boiler and then enters a secondary converter for secondary catalysis after removing nitrogen oxides. The inlet temperature of the primary catalysis is 390°C and the inlet gas flow rate is 9258Nm 3 / h, the inlet SO2 concentration is 4.1vol%. The outlet temperature of the first catalytic is 530℃, the inlet temperature of the second catalytic is 390℃, the outlet temperature is 405℃, the catalysts of the first catalytic and the second catalytic are vanadium catalysts, the filling coefficient is 800L / (t*d), and a process gas S3 rich in SO3 is obtained. The process gas rich in SO3 enters a condenser and is condensed at 255℃ to obtain a first sulfuric acid and a condensed gas. The inlet temperature of the process gas rich in SO3 entering the condenser is 296℃, and the outlet condenser temperature is 89℃;

[0110] S4, contacting the condensed gas with rhodium metal-modified activated carbon at 50°C for 0.1h, spraying the generated SO3 with deionized water to obtain a second sulfuric acid and tail gas, returning the second sulfuric acid to step S3 and mixing it with the first sulfuric acid, wherein the loading amount of the noble metal is 0.7wt‰ based on the total weight of the noble metal-modified activated carbon, and the amount of the noble metal-modified activated carbon is 60Nm 3 .

[0111] Among them, the total conversion rate of SO2 is 99%, and the SO2 content in the tail gas is 19mg / Nm 3 , the content of nitrogen oxides is 25mg / Nm 3 , acid mist content is 0.03g / Nm 3 .

[0112] Example 6

[0113] S1, same as Example 4;

[0114] S2, the SO2-rich process gas is heat exchanged in a high-temperature waste heat boiler, and then enters a four-stage converter for four-stage catalysis after removing nitrogen oxides. The inlet temperature of the first-stage catalysis is 410°C, and the inlet gas flow rate is 15828Nm 3 / h, the inlet SO2 concentration is 5.05vol%. The outlet temperature of the first catalytic is 519°C, the inlet temperature of the second catalytic is 410°C, the outlet temperature is 422°C, the catalysts of the first and second catalytic are vanadium catalysts, the loading factor is 710L / (t*d), the inlet temperature of the third catalytic is 400°C, the outlet temperature is 409°C, the inlet temperature of the fourth catalytic is 390°C, the outlet temperature is 400°C, the catalysts of the third and fourth catalytic are platinum catalysts, the loading factor is 5L / (t*d), and a process gas S3 rich in SO3 is obtained, the process gas rich in SO3 is introduced into a condenser and condensed at 258°C to obtain a first sulfuric acid and a condensed gas, the inlet temperature of the process gas rich in SO3 entering the condenser is 289°C, and the outlet condenser temperature is 88°C;

[0115] S4, contacting the condensed gas with palladium and rhodium metal modified activated carbon at 60°C for 0.2h, spraying the generated SO3 with deionized water to obtain a second sulfuric acid and tail gas, returning the second sulfuric acid to step S3 and mixing it with the first sulfuric acid, wherein the loading amount of the noble metal is 1wt‰ based on the total weight of the noble metal modified activated carbon, and the amount of the noble metal modified activated carbon is 65Nm 3 .

[0116] Among them, the total conversion rate of SO2 is 99.7%, and the SO2 content in the tail gas is 5mg / Nm 3 , the content of nitrogen oxides is 20mg / Nm 3, acid mist content is 0.01g / Nm 3 .

[0117] Example 7

[0118] S1, same as Example 4;

[0119] S2, the SO2-rich process gas is heat exchanged in a high-temperature waste heat boiler, and then enters a four-stage converter for four-stage catalysis after removing nitrogen oxides. The inlet temperature of the first-stage catalysis is 390°C, and the inlet gas flow rate is 8050Nm 3 / h, the inlet SO2 concentration is 1.98vol%. The outlet temperature of the first catalytic converter is 440℃, the inlet temperature of the second catalytic converter is 390℃, the outlet temperature is 395℃, the catalysts of the first and second catalytic converters are vanadium catalysts, the loading factor is 920L / (t*d), the inlet temperature of the third catalytic converter is 390℃, the outlet temperature is 393℃, the inlet temperature of the fourth catalytic converter is 390℃, the outlet temperature is 392℃, the catalysts of the third and fourth catalytic converters are platinum catalysts, the loading factor is 6L / (t*d), and a process gas rich in SO3 is obtained;

[0120] S3, the SO3-rich process gas enters a condenser and is condensed at 252° C. to obtain first sulfuric acid and condensed gas, wherein the SO3-rich process gas has an inlet temperature of 290° C. when entering the condenser and an outlet temperature of 90° C. when entering the condenser;

[0121] S4, contacting the condensed gas with rhodium and platinum metal modified activated carbon at 40°C for 0.1h, spraying the generated SO3 with deionized water to obtain a second sulfuric acid and tail gas, returning the second sulfuric acid to step S3 and mixing it with the first sulfuric acid, wherein the loading amount of the noble metal is 0.4wt‰ based on the total weight of the noble metal modified activated carbon, and the amount of the noble metal modified activated carbon is 65Nm 3 .

[0122] Among them, the total conversion rate of SO2 is 99.5%, and the SO2 content in the tail gas is 2mg / Nm 3 , the content of nitrogen oxides is 25mg / Nm 3 , acid mist content is 0.02g / Nm 3 .

[0123] Example 8

[0124] The method of Example 1 is followed, except that the catalysts from the first stage to the third stage are all vanadium catalysts.

[0125] S1. The acidic gas containing hydrogen sulfide generated by the combustion of the upstream medium-sulfur coal is introduced into the incinerator, mixed with the cold air from the outside and the hot air from the bottom of the condenser for combustion at a combustion temperature of 1000°C to obtain a process gas rich in SO2, wherein the SO2 content is 4.1 vol%;

[0126] S2, the SO2-rich process gas is heat exchanged in a high-temperature waste heat boiler, and then the nitrogen oxides are removed and then enter the three-stage converter for three-stage catalysis. The inlet temperature of the first-stage catalysis is 410°C, and the inlet gas flow rate is 20503Nm 3 / h, the inlet SO2 concentration is 4.1vol%. The outlet temperature of the first stage catalyst is 500℃, the inlet temperature of the second stage catalyst is 420℃, the outlet temperature is 425℃, the inlet temperature of the third stage catalyst is 390℃, the outlet temperature is 392℃, the filling coefficient is 786L / (t*d), and a process gas rich in SO3 is obtained;

[0127] S3, the SO3-rich process gas enters a condenser and is condensed at 255° C. to obtain first sulfuric acid and condensed gas, wherein the SO3-rich process gas has an inlet temperature of 290° C. entering the condenser and an outlet condenser temperature of 90° C.;

[0128] S4, contacting the condensed gas with activated carbon modified with platinum metal at 40°C for 0.3h, spraying the generated SO3 with deionized water to obtain a second sulfuric acid and tail gas, returning the second sulfuric acid to step S3 and mixing it with the first sulfuric acid, wherein the loading amount of the noble metal is 0.6wt‰ based on the total weight of the activated carbon modified with the noble metal, and the amount of the activated carbon modified with the noble metal is 60Nm 3 .

[0129] Among them, the total conversion rate of SO2 is 99.1%, and the SO2 content in the tail gas is 10mg / Nm 3 , the content of nitrogen oxides is 30mg / Nm 3 , acid mist content is 0.03g / Nm 3 .

[0130] Comparative Example 1

[0131] S1. The acidic gas containing hydrogen sulfide generated by the combustion of the upstream medium-sulfur coal is introduced into the incinerator, mixed with the cold air from the outside and the hot air from the bottom of the condenser for combustion at a combustion temperature of 1000°C to obtain a process gas rich in SO2, wherein the SO2 content is 5 vol%;

[0132] S2, the SO2-rich process gas is heat exchanged in a high-temperature waste heat boiler, and then enters a three-stage converter for three-stage catalysis after removing nitrogen oxides. The inlet temperature of the first-stage catalysis is 410°C, and the inlet gas flow rate is 20503Nm 3 / h, the inlet SO2 concentration is 4.1vol%. The outlet temperature of the first-stage catalyst is 500℃, the inlet temperature of the second-stage catalyst is 420℃, the outlet temperature is 425℃, the catalysts of the first-stage catalyst and the second-stage catalyst are vanadium catalysts, and the filling coefficient is 500L / (t*d). The inlet temperature of the third-stage catalyst is 390℃, the outlet temperature is 392℃, the catalyst of the third-stage catalyst is platinum catalyst, and the filling coefficient is 5L / (t*d), and a process gas rich in SO3 is obtained;

[0133] S3. The SO3-rich process gas is fed into a condenser and condensed at 255°C to obtain first sulfuric acid and condensed gas. The SO3-rich process gas has an inlet temperature of 290°C and an outlet temperature of 90°C when entering the condenser.

[0134] Among them, the total conversion rate of SO2 is 89.8%, and the SO2 content in the condensed gas is 90mg / Nm 3 , the content of nitrogen oxides is 30mg / Nm 3， , acid mist content is 0.04g / Nm 3 .

[0135] Comparative Example 2

[0136] S1. The acidic gas containing hydrogen sulfide generated by the combustion of the upstream medium-sulfur coal is introduced into the incinerator, mixed with the cold air from the outside and the hot air from the bottom of the condenser for combustion at a combustion temperature of 1000°C to obtain a process gas rich in SO2, wherein the SO2 content is 4.6 vol%;

[0137] S2, the SO2-rich process gas is heat exchanged in a high-temperature waste heat boiler, and then enters a three-stage converter for three-stage catalysis after removing nitrogen oxides. The inlet temperature of the first-stage catalysis is 410°C, and the inlet gas flow rate is 20503Nm 3 / h, the inlet SO2 concentration is 4.1vol%. The outlet temperature of the first-stage catalyst is 500℃, the inlet temperature of the second-stage catalyst is 420℃, the outlet temperature is 425℃, the catalysts of the first-stage catalyst and the second-stage catalyst are vanadium catalysts, and the filling coefficient is 780L / (t*d). The inlet temperature of the third-stage catalyst is 390℃, the outlet temperature is 392℃, the catalyst of the third-stage catalyst is a platinum catalyst, and the filling coefficient is 2L / (t*d), and a process gas rich in SO3 is obtained;

[0138] S3, the SO3-rich process gas enters a condenser and is condensed at 260° C. to obtain first sulfuric acid and condensed gas, wherein the SO3-rich process gas has an inlet temperature of 290° C. when entering the condenser and an outlet temperature of 90° C. when entering the condenser;

[0139] S4, contacting the condensed gas with activated carbon to obtain a second sulfuric acid and tail gas

[0140] Among them, the total conversion rate of SO2 is 89.9%, and the SO2 content in the tail gas is 41mg / Nm 3 , the content of nitrogen oxides is 30mg / Nm 3 , acid mist content is 0.03g / Nm 3 .

[0141] It can be seen from the above results that when sulfuric acid is prepared by the method of the present invention, the total SO2 conversion rate of the process is high, and the content of SO2 and nitrogen oxides in the tail gas is low.

[0142] Among them, the specific catalyst loading coefficient is matched with vanadium-based and platinum-based catalysts, and the method of modifying activated carbon with precious metals can achieve better technical effects. The total SO2 conversion rate of the process is not less than 99.1%, and the SO2 content in the tail gas is not higher than 8mg / Nm 3 , the content of nitrogen oxides is not higher than 25g / Nm 3 .

[0143] In Comparative Example 1, the activated carbon modified with precious metals is not used for further adsorption and catalysis of the condensed gas, which will result in higher SO2 and nitrogen oxide contents in the condensed gas, and a slight decrease in the overall SO2 conversion rate.

[0144] In Comparative Example 2, activated carbon is used instead of activated carbon modified with precious metals to adsorb the condensate gas, which also results in higher SO2 and nitrogen oxide contents in the condensate gas.

[0145] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing sulfuric acid by wet hydrogen sulfide, characterized in that: include: S1, burning the acidic gas containing hydrogen sulfide to obtain a process gas rich in SO2; S2, subjecting the SO2-rich process gas to multi-stage catalysis to obtain SO3-rich process gas; S3, condensing the SO3-rich process gas to obtain first sulfuric acid and condensed gas; S4. Contacting the condensed gas with activated carbon modified with precious metals to obtain a second sulfuric acid and tail gas.

2. The method according to claim 1, wherein: In the noble metal-modified activated carbon, the noble metal is selected from at least one of platinum, rhodium or palladium; Preferably, based on the total weight of the noble metal-modified activated carbon, the content of the noble metal is 0.5-1.5 wt‰, preferably 1-1.5 wt‰.

3. The method according to claim 1 or 2, wherein: Based on the total volume of the condensed gas, the amount of the noble metal-modified activated carbon is 50 Nm 3 -100Nm 3 , preferably 55Nm 3 -65Nm 3 .

4. The method according to any one of claims 1 to 3, wherein: The multi-stage catalysis includes at least three stages; Preferably, in the multi-stage catalysis, the process gas generated by each stage of catalysis is heat exchanged before entering the next stage of catalysis.

5. The method according to claim 4, wherein: The multi-stage catalysis includes primary catalysis, secondary catalysis and tertiary catalysis, wherein the primary catalysis and the secondary catalysis are carried out in the presence of a vanadium catalyst, and the tertiary catalysis is carried out in the presence of a platinum catalyst; Preferably, the inlet temperature of the first-stage catalyst is 380-440°C, and the outlet temperature of the first-stage catalyst is 490-560°C; The inlet temperature of the secondary catalyst is 400-430°C, and the outlet temperature of the secondary catalyst is 450-480°C; The inlet temperature of the three-stage catalyst is 380-400°C, and the outlet temperature of the three-stage catalyst is 382-405°C; Or, the multi-stage catalysis includes primary catalysis, secondary catalysis, tertiary catalysis and quaternary catalysis, wherein the primary catalysis and the secondary catalysis are carried out in the presence of a vanadium catalyst, and the tertiary catalysis and the quaternary catalysis are carried out in the presence of a platinum catalyst; Preferably, the inlet temperature of the first-stage catalyst is 380-440°C, and the outlet temperature of the first-stage catalyst is 490-560°C; The inlet temperature of the secondary catalyst is 400-430°C, and the outlet temperature of the secondary catalyst is 450-480°C; The inlet temperature of the three-stage catalyst is 380-400°C, and the outlet temperature of the three-stage catalyst is 382-405°C; The inlet temperature of the four-stage catalyst is 390-400°C, and the outlet temperature of the four-stage catalyst is 391-401°C.

6. The method according to claim 5, wherein: The filling factor of the vanadium catalyst is 500-1200 L / (t*d), preferably 550-900 L / (t*d); Preferably, the packing factor of the platinum catalyst is 5-10 L / (t*d), preferably 6-8 L / (t*d); Preferably, the platinum catalyst comprises a porous carrier and a platinum active component supported on the porous carrier; Preferably, based on the total weight of the platinum catalyst, the content of the metal platinum is 0.5-2wt‰, preferably 0.5-1wt‰; Preferably, the porous carrier is selected from at least one of titanium dioxide, diatomaceous earth, montmorillonite and attapulgite.

7. The method according to any one of claims 1 to 6, wherein: The content of H2S in the acidic gas containing hydrogen sulfide is 30-90 vol%; Preferably, the SO2 content in the SO2-rich process gas is 1.5-6.5 vol%; Preferably, in step S1, the combustion temperature is 900-1100°C.

8. The method according to any one of claims 1 to 7, wherein: The method further comprises: before the multi-stage catalysis, adjusting the temperature of the SO2-rich process gas to 380-440°C; Preferably, the content of SO2 in the condensed gas is 100-500 ppm; Preferably, the second sulfuric acid is returned to step S3 for recycling.

9. The method according to any one of claims 1 to 8, wherein: In step S3, the condensation temperature is 250-260°C; Preferably, in step S4, the contact conditions include: contact temperature of 30-80° C., and contact time of 0.1-0.5 h.

10. The method according to any one of claims 1 to 9, wherein: The content of SO2 in the tail gas is ≤10mg / Nm 3 , acid mist content ≤ 0.03g / Nm 3 , nitrogen oxide content ≤30mg / Nm 3 .