CN104208992A - Method for desulfurizing acid gas containing hydrogen sulfide and recycling sulfur - Google Patents

Abstract

A method for desulfurizing acidic gas containing hydrogen sulfide and recovering sulfur, comprising the following steps in sequence: feeding the acidic gas into a combustion furnace, mixing it with air fed from another pipeline for combustion reaction; reacting in the combustion furnace The final gas enters the desuperheater and cools down to 230-250°C. After cooling, the liquid sulfur is separated from the liquid outlet, and the mixed gas in the combustion furnace enters the catalyst reactor, and the hydrogen sulfide and sulfur dioxide react in the catalyst reactor. Sulfur and water are generated, and the generated liquid sulfur is separated from the liquid outlet of the catalyst reactor; the mixed gas in the catalyst reactor enters the hydrogenation reactor, and the sulfur dioxide in the hydrogenation reactor reacts with hydrogen; The gas enters the hydrogen sulfide absorption device, and hydrogen sulfide is generated into elemental sulfur under the action of alkaline solution, complex catalyst and air. The advantages are: short process route, high quality sulfur and low energy consumption. Can completely remove SO ₂ gas, green and environmental protection.

Description

Method for desulfurizing acid gas containing hydrogen sulfide and recovering sulfur

technical field

The invention relates to the technical field of industrial waste gas treatment, in particular to a method for desulfurizing acid gas containing hydrogen sulfide and recovering sulfur.

Background technique

With the rapid development of my country's economy, the demand for raw materials such as coal, oil, and natural gas continues to increase. Due to the small amount of oil and natural gas in my country, most of them rely on imports from abroad. With the increasing demand in the national market, it is difficult to import high-quality raw materials, and price competition is incentivized. In order to reduce costs, most of the imported raw materials contain high sulfur content. In order to meet subsequent customer and market demands, sulfur must be removed. The sulfur recovery process has been introduced and developed in China for nearly 40 years, showing a parallel development trend of domestic free technology and international technology. In 1883, the British scientist Claus first proposed the process of recovering sulfur from H ₂ S gas. After more than 100 years of development, the technology has been greatly improved. According to statistics, from 2000 to 2003, the number of sulfur recovery devices in China increased from 62 to more than 100, and by 2014, nearly 50 large and medium-sized devices were put into operation. Although the economy is developing rapidly, the environmental pollution has been serious in recent years, especially the smog weather has caused great harm to the environment, and SO ₂ has made a great contribution to the smog weather. In order to control the environment, the SO ₂ content in the exhaust gas will In 2015, it was reduced to below 50mg/m ³ . 95% of SO ₂ emissions from all domestic sulfur recovery units are not up to standard. Over the years, although the sulfur recovery process has been reformed and improved many times, and tail gas treatment measures have been added, the process principle has not changed. Most of the technologies used now are based on improved Claus, based on basic theory, process flow, catalyst development, The equipment structure and material, automatic control scheme and interlocking have been developed and improved in many aspects, but in the end the zero discharge of pollutants has not been completely realized. An existing Chinese invention patent with the application number CN96102799.1 titled "A Method for Extracting Elemental Sulfur from a Mixed Gas Containing H ₂ S" discloses a method for extracting elemental sulfur from a mixed gas containing H ₂ S method, wherein the mixed gas is firstly desulfurized in a Claus plant with simultaneous production of elemental sulfur, and secondly, the sulfur compounds still contained in the Claus off-gas are converted into H ₂ S by hydrogenation, followed by hydrogenation The Claus exhaust gas undergoes direct catalytic oxidation of H ₂ S and generates elemental sulfur. However, this invention cannot completely remove SO ₂ , gas emissions, and the absorption and treatment of H ₂ S consumes a lot of energy. Therefore, it is necessary to further improve the method.

Contents of the invention

The technical problem to be solved by the present invention is to provide a desulfurization and sulfur recovery method that can not only desulfurize but also recover sulfur, and hydrogen sulfide in acid gas can be completely removed in view of the above-mentioned prior art.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is: the method for desulfurizing acid gas containing hydrogen sulfide and recovering sulfur, which is characterized in that it includes the following steps in sequence:

Step 1. Pass the acid gas containing hydrogen sulfide into the combustion furnace, and mix it with the air passing into the combustion furnace from another pipeline to carry out the combustion reaction. The inlet pressure of the acid gas passed into the combustion furnace is maintained at 20- 100KPa; the reaction equation is: 2H ₂ S+O ₂ →2S↓+2H ₂ O; 2H ₂ S+3O ₂ →2SO ₂ +2H ₂ O;

Step 2. The reacted gas in the combustion furnace enters the cooling device to cool down to 230-250°C. After cooling, the liquid sulfur is separated from the liquid outlet, and the incompletely burnt hydrogen sulfide gas in the combustion furnace is formed after combustion. The mixed gas of sulfur dioxide gas enters the catalyst reactor, and under the action of the base catalyst in the catalyst reactor, the hydrogen sulfide and sulfur dioxide react to form sulfur and water, and the generated liquid sulfur is separated from the liquid outlet of the catalyst reactor. The reaction equation is : 2H ₂ S+SO ₂ →3S↓+2H ₂ O;

Step 3. Put the unreacted hydrogen sulfide and sulfur dioxide mixed gas in the catalyst reactor into the hydrogenation reactor whose pressure is kept at 20-100KPa, and the sulfur dioxide in the mixed gas reacts with hydrogen in the hydrogenation reactor to reduce the sulfur dioxide into hydrogen sulfide, the reaction equation is: SO ₂ +3H ₂ →H ₂ S+2H ₂ O;

Step 4, the hydrogen sulfide and sulfur dioxide in the hydrogenation reactor are reduced to hydrogen sulfide by hydrogen into the hydrogen sulfide absorption device with a built-in alkaline solution and complex catalyst, and the hydrogen sulfide is dissolved in the alkaline solution, Elemental sulfur is generated under the action of the complex catalyst and air, and the reaction equation is:

·CO ₃ ^2- +CO ₂ +H ₂ O→2HCO ₃ ^-

·H ₂ S+OH ^- →HS ^- +H ₂ O

·Fe ³⁺ (complexed state)+HS ^- →Fe ²⁺ (complexed state)+S+H ⁺

The overall reaction formula is: Fe ³⁺ (complexed state)+H ₂ S+OH ^- →Fe ²⁺ (complexed state)+S↓+H ₂ O

That is, the steps of desulfurization and sulfur recovery are completed.

As an improvement, the hydrogen sulfide absorption device in step 4 is fed with air at intervals until no more precipitation occurs.

As a further improvement, the time for feeding air each time is 0.2-3 seconds.

As an improvement, the reacted gas in the combustion furnace in step 1 enters a desuperheater with a pressure of 20-100KPa to cool down to 230-250°C.

As an improvement, in step 3, the mixed gas of hydrogen sulfide and sulfur dioxide not completely reacted in the catalyst reactor enters into the hydrogenation reactor whose pressure is kept at 20-100KPa.

As an improvement, the reaction temperature in the hydrogen sulfide absorption device in the step 4 is kept at 50-60°C.

As an improvement, the reaction temperature of gas combustion in the combustion furnace is kept at 980-1370° C., and the reaction time is 0.5-3 seconds.

As an improvement, the reaction temperature in the catalyst reactor is kept at 265-275° C., and the reaction time is 3-10 seconds.

As an improvement, the liquid sulfur generated by the reaction of the combustion furnace and the catalyst reactor is collected uniformly through pipelines into the sulfur pool, and the liquid sulfur in the sulfur pool is transported by a sulfur pump to a sulfur granulator to produce solid sulfur.

As an improvement, the catalyst is a complex catalyst, the base catalyst is Al ₂ O ₃ , and the alkaline solution is Na ₂ CO ₃ solution.

Compared with the prior art, the method for desulfurizing acid gas containing hydrogen sulfide and recovering sulfur of the present invention has the following advantages: the process route is short, the manufacturing and processing of the equipment used is simple, the localization can be fully realized, the catalyst activity is good, and the production of sulfur Good quality, low energy consumption and convenient control. After the desulfurization operation of this process, more than 95% of the H ₂ S in the gas is converted into elemental sulfur, and the SO ₂ in the remaining gas is completely converted into H ₂ S, and the gas leaving the third reactor contains a small amount of H ₂ S, which passes through the hydrogen sulfide absorption device , absorb almost all of the H ₂ S, so that the H ₂ S gas is converted into elemental sulfur under the action of O ₂ and the catalyst, and the gas achieves the purpose of removing H 2 S, and the _{H 2 S} content in the final gas is less than 1ppM, and the SO ₂ content is zero . The catalyst adopts complexes of variable-valence metal iron, which is a compound complex system of two metal irons. It has stable performance when used in sulfur-containing solutions, high desulfurization efficiency, strong regeneration ability, and effective sulfur capacity can reach 0.60g/L (within H ₂ S content ≤ 1500mg/Nm ³ (calculated), the H ₂ S content after desulfurization can reach below 5mg/Nm ³ , and the catalyst is equipped with a variety of functional additives, which can improve the stability of the catalyst and reduce the degradation rate. Improve the surface properties of sulfur particles and make them grow up. The particle size of most of the sulfur particles measured by the laser particle size analyzer of the Institute of Materials, Chinese Academy of Sciences is 11 μm. The sulfur foam is rich and stable and easy to remove; the regeneration reaction is complete, forming a binary catalyst oxidation system. Accelerate the regeneration reaction speed, increase the HS-oxidation rate in the solution after absorption, and minimize the HS ^- concentration in the solution leaving the hydrogen sulfide absorption device; the solution contains ionic surface active substances, which can reduce the surface tension of the solution and make the elemental sulfur Relatively enriched, it is very easy to precipitate from the sulfur solution, the content of suspended sulfur is low, and it is not easy to accumulate and block. The temperature of the hydrogen sulfide absorption device is kept at 50-60°C. When the temperature is 50-60°C, the absorption of CO ₂ by the solution is small, which is beneficial to the removal of H ₂ S. High-temperature absorption can accelerate the desorption of HCO3 ^- , generate CO3 ^2- , stabilize the pH of the solution, and reduce the alkali consumption.

Description of drawings

Fig. 1 is a schematic structural diagram of a device applying the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1, the method for desulfurizing acid gas containing hydrogen sulfide and reclaiming sulfur of the present invention comprises the following steps successively:

Step 1, the acid gas containing hydrogen sulfide is passed into the combustion furnace 1, mixed with the air passing into the combustion furnace 1 from another pipeline to carry out the combustion reaction, the intake pressure of the acid gas passed into the combustion furnace 1 is kept 20～100KPa; the reaction equation is: 2H ₂ S+O ₂ →2S↓+2H ₂ O; 2H ₂ S+3O ₂ →2SO ₂ +2H ₂ O;

Step 2: The gas reacted in the combustion furnace 1 enters the cooling device 2 to cool down to 230-250°C, and the liquid sulfur is separated from the liquid outlet after cooling, while the incompletely burned hydrogen sulfide gas in the combustion furnace 1 and The mixed gas of sulfur dioxide gas generated after combustion enters the catalytic reactor 3, and under the action of the base catalyst in the catalytic reactor 3, hydrogen sulfide and sulfur dioxide are reacted to generate sulfur and water, and the liquid sulfur generated is released from the liquid in the catalytic reactor 3. The outlet is separated, and the reaction equation is: 2H ₂ S+SO ₂ →3S↓+2H ₂ O;

Step 3, enter the mixed gas of unreacted hydrogen sulfide and sulfur dioxide in the catalyst reactor 3 into the hydrogenation reactor 4 whose pressure is maintained at 20-100KPa, and react the sulfur dioxide and hydrogen of the mixed gas in the hydrogenation reactor 4 to form Reducing sulfur dioxide to hydrogen sulfide, the reaction equation is: SO ₂ +3H ₂ →H ₂ S+2H ₂ O;

Step 4, the hydrogen sulfide and sulfur dioxide in the hydrogenation reactor 4 are reduced to hydrogen sulfide gas by hydrogen into the hydrogen sulfide absorption device 5 which has a built-in alkaline solution and a complex catalyst, and the hydrogen sulfide in the alkaline Elemental sulfur is generated under the action of solution, complex catalyst and air, and the reaction equation is:

·CO ₃ ^2- +CO ₂ +H ₂ O→2HCO ₃ ^-

·H ₂ S+OH ^- →HS ^- +H ₂ O

·Fe ³⁺ complex state+HS ^- →Fe ²⁺ complex state+S+H ⁺

The overall reaction formula is: Fe ³⁺ complex state + H ₂ S + OH ^- → Fe ²⁺ complex state + S↓ + H ₂ O

That is, the steps of desulfurization and sulfur recovery are completed.

The hydrogen sulfide absorbing device 5 in the step 4 is fed with air at intervals until no more precipitation occurs. The time for feeding air each time is 0.2 to 3 seconds. The gas reacted in the combustion furnace 1 in step 1 enters the desuperheater 2 with a pressure of 20-100KPa and cools down to 230-250°C. In Step 3, the unreacted hydrogen sulfide and sulfur dioxide mixed gas in the catalyst reactor 3 enters into the hydrogenation reactor 4 whose pressure is maintained at 20-100KPa. The reaction temperature in the hydrogen sulfide absorption device 5 in the step 4 is kept at 50-60°C. The reaction temperature of gas combustion in the combustion furnace 1 is kept at 980-1370° C., and the reaction time is 0.5-3 seconds. The reaction temperature in the catalyst reactor 3 is kept at 265-275° C., and the reaction time is 3-10 seconds. The liquid sulfur generated by the reaction of the combustion furnace 1 and the catalyst reactor 3 is respectively collected into the sulfur pool 6 through pipelines, and the liquid sulfur in the sulfur pool 6 is transported by a sulfur pump to a sulfur granulator to produce solid sulfur. The catalyst is a complex catalyst, the base catalyst is Al ₂ O ₃ , and the alkaline solution is Na ₂ CO ₃ solution.

Claims (10)

1. A method for desulfurizing acid gas containing hydrogen sulfide and reclaiming sulfur, characterized in that: comprising the steps successively: Step 1, pass the acid gas containing hydrogen sulfide into the combustion furnace (1), and mix it with the air passing into the combustion furnace (1) from another pipeline to carry out the combustion reaction, the acid gas passed into the combustion furnace (1) The gas inlet pressure is kept at 20~100KPa; the reaction equation is: 2H ₂ S+O ₂ →2S↓+2H ₂ O; 2H ₂ S+3O ₂ →2SO ₂ +2H ₂ O; Step 2: The gas reacted in the combustion furnace (1) enters the cooling device (2) and cools down to 230-250 ° C. After cooling, the liquid sulfur is separated from the liquid outlet, and the incomplete combustion in the combustion furnace (1) The mixed gas of the exhausted hydrogen sulfide gas and the sulfur dioxide gas generated after combustion enters the catalyst reactor (3), and under the action of the base catalyst in the catalyst reactor (3), the hydrogen sulfide and sulfur dioxide react to form sulfur and water, forming The liquid sulfur is separated from the liquid outlet of the catalyst reactor (3), and the reaction equation is: 2H ₂ S+SO ₂ →3S↓+2H ₂ O; Step 3. Enter the mixed gas of unreacted hydrogen sulfide and sulfur dioxide in the catalyst reactor (3) into the hydrogenation reactor (4) whose pressure is maintained at 20-100KPa, and mix the gas in the hydrogenation reactor (4) Sulfur dioxide reacts with hydrogen to reduce sulfur dioxide to hydrogen sulfide. The reaction equation is: SO ₂ +3H ₂ →H ₂ S+2H ₂ O; Step 4, hydrogen sulfide and sulfur dioxide in the hydrogenation reactor (4) are reduced to hydrogen sulfide gas by hydrogen into the hydrogen sulfide absorption device (5) that has a built-in alkaline solution and complex catalyst, and the sulfide Hydrogen generates elemental sulfur under the action of alkaline solution, complex catalyst and air, and the reaction equation is: ·CO ₃ ^2- +CO ₂ +H ₂ O→2HCO ₃ ^- ·H ₂ S+OH ^- →HS ^- +H ₂ O ·Fe ³⁺ (complexed state)+HS ^- →Fe ²⁺ (complexed state)+S+H ⁺ The overall reaction formula is: Fe ³⁺ (complexed state)+H ₂ S+OH ^- →Fe ²⁺ (complexed state)+S↓+H ₂ O That is, the steps of desulfurization and sulfur recovery are completed. 2. The method according to claim 1, characterized in that: the hydrogen sulfide absorption device (5) in step 4 feeds air at intervals until precipitation no longer occurs. 3. The method according to claim 2, characterized in that: each time the air is introduced is 0.2-3 seconds. 4. The method according to any one of claims 1 to 3, characterized in that: the reacted gas in the combustion furnace (1) of step 1 enters a pressure reducer (2) with a pressure of 20 to 100KPa to cool down to 230～250℃. 5. The method according to any one of claims 1 to 3, characterized in that: in step 3, the unreacted hydrogen sulfide and sulfur dioxide mixed gas in the catalyst reactor (3) enters until the pressure is maintained at 20 ~ In the hydrogenation reactor (4) of 100KPa. 6. The method according to any one of claims 1-3, characterized in that: the reaction temperature in the hydrogen sulfide absorbing device (5) in the step 4 is kept at 50-60°C. 7. The method according to any one of claims 1 to 3, characterized in that: the reaction temperature of gas combustion in the combustion furnace (1) is kept at 980-1370° C., and the reaction time is 0.5-3 seconds. 8. The method according to any one of claims 1 to 3, characterized in that: the reaction temperature in the catalyst reactor (3) is maintained at 265-275° C., and the reaction time is 3-10 seconds. 9. The method according to any one of claims 1 to 3, characterized in that: the liquid sulfur generated by the reaction of the combustion furnace (1) and the catalyst reactor (3) is respectively uniformly collected into the sulfur pool (6) through pipelines In the process, the liquid sulfur in the sulfur pool (6) is transported by a sulfur pump to a sulfur granulator to produce solid sulfur. 10. The method according to any one of claims 1 to 3, characterized in that: the catalyst is a complex catalyst, the base catalyst is Al ₂ O ₃ , and the alkaline solution is Na ₂ CO ₃ solution .