What to do if the CO2 content in sour gas is high
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The acid gas of our sulfur recovery unit has a high CO2 content, which inhibits the conversion rate. Can anyone suggest a solution?
Acid gas is the raw material for sulfur recovery equipment, and it generally comes from several sources.: 1. Sewage stripping 2. Hydrogenation to low fraction. Stripping tower 3. Coking. Catalytic liquefied gas. Dry gas desulfurization. The main components of sour gas are hydrogen sulfide, light hydrocarbons, carbon monoxide, and carbon dioxide. If the carbon dioxide content is high, then add desulfurization (ethanol ammonia).
There are two main sources of raw gas for sulfur recovery, one is the acid gas regenerated from the solvent, and the other is the acid gas extracted from the acidic water vapor. CO2 mainly exists in the acid gas produced by solvent regeneration. The reason why there is more CO2 is that the solvent absorption selectivity is too poor. While absorbing hydrogen sulfide, it also absorbs too much carbon dioxide. It is recommended to change to a solvent with better selectivity. The better solvent at present is MDEA. Second, there is a problem with the operation of the absorption tower, and the solvent circulation volume is too large. It is recommended to minimize the amount of solvent circulation while ensuring quality. It does not mean that the cleaner the absorption, the better. The above is a permanent solution. The temporary solution is to increase the temperature of the first-stage CLAUS reactor, because the reason why CO2 affects the sulfur recovery rate is largely due to the reaction between CO2 and S to generate CS2, etc. Increasing the temperature of the first-stage CLAUS reactor can promote the hydrolysis reaction of CS2, etc., and increase the S recovery rate. If there is a RAR section, try to increase the temperature of the hydrogenation reactor and increase the amount of H2 at the same time. Of course, other parts of RAR are also adjusted accordingly. good luck. . . . . .
"The reason why CO2 affects the sulfur recovery rate is largely because CO2 reacts with S to form CS2, etc." I'm afraid this sentence is not quite right. I think the carbon dioxide is too high, which affects the acid gas concentration, which in turn affects the temperature of the combustion furnace, and finally affects the sulfur recovery rate.
I think: 1. Hydrocarbons in rich liquid and acidic water are not removed to the required level. 2. The amount of lean liquid during exhaust gas absorption must be controlled! 3. If the working conditions permit, you can consider the two-line CLAUS system for high and low load feeding! Rough opinions and suggestions! ! !
Dear posters, this is a systematic project, and we may be able to do a good job.