High COS content in exhaust gases: causes and treatment methods?

The high COS content in the exhaust gases is mainly caused by improper selection of the reaction furnace burners or side reactions resulting from an excessive amount of acidic hydrocarbons. The best approach is to choose a more suitable burner, and try to avoid the presence of oil and hydrocarbons in the acidic gases. Furthermore, loading a titanium-based catalyst on the opposite side can increase the conversion rate of COS. Under no circumstances should steam be introduced into the reactor, as this will reduce the strength of the catalyst and shorten its lifespan.

The acid gas may contain a significant amount of CH4, and if this CH4 is not oxidized in the flame zone, it will react with SO2 inside the combustion furnace to form COS. Agree to choose a more suitable burner as suggested above, or use oxygen-enriched combustion to increase the temperature. Running steam – theoretically, it seems to serve no purpose; dilution? ----------------- Is it because there is too little H2O in the process gas, which hinders the progress of the hydrolysis reaction, that steam is introduced? If that’s the case, applying steam should work. This post was last edited by haichuaner on 2009-3-24 16:55]

A high COS value indicates two things: on one hand, it means too much is produced by the reactor； On the other hand, it is because the hydrolysis in the reactor is not good. First, try raising the temperature of the converted gas to around 330 degrees; it should work

To enable the hydrolysis reaction of COS and CS2, the temperature of the process gas at the outlet of the primary converter must be maintained between 310–340 degrees, or even as high as 370 degrees

”Raise the temperature of the converted gas to around 330 degrees. “How can it be increased?” Increase the inlet temperature?

First, conduct a sample analysis of acidity to check the levels of hydrocarbons and methane to see if they are high. In that case, seek a solution from the upstream party. If it’s due to poor system combustion or poor converter reaction. A specific analysis of the reasons is required; the combustion furnace must have a high enough temperature and residence time, with a minimum of 1050 degrees and a residence time of 1.5 seconds. The converter should be equipped with a titanium-based catalyst; if it is not present, reinstalling one is not feasible. It is possible to increase the reaction temperature of the bed layer, control the air supply properly, and use a high-dilution valve to raise the inlet temperature of the converter.

Generally, COS is generated as a by-product of reactions within the furnace; it may result from excessive hydrocarbons or oils in the acidic gases. Moreover, it is usually difficult to eliminate this substance in the first and second reaction stages in the downstream process. I’m not sure which specific part of the exhaust gas you are referring to ? In our workshop, the content of COS can be effectively reduced in the hydrogenation reactor; even if hydrogenation is not in use, in the exhaust gas incinerator, proper temperature control should allow for complete combustion, resulting in the formation of SO2.

1. The feed gas may contain a high amount of hydrocarbons, so it is necessary to contact the facility responsible to ensure proper production. II. Raising the temperature of the reactor to above 300 degrees is beneficial for hydrolysis. Three. Use an efficient catalyst IV. You may not have the Scott process; it is recommended to use that method, as it will ensure almost complete conversion of COS.

Increase the inlet temperature, as the hydrolysis temperature of cos is 326 degrees; therefore, the temperature within the bed must be raised above 326 degrees. However, the hydrolysis reaction is an exothermic reaction, which causes a temperature rise inside the reactor. The operating temperature for catalysts is generally considered high when it reaches 400 degrees; prolonged exposure to such high temperatures can affect the catalyst’s activity. The best way to solve this problem is by using a titanium oxide catalyst, which has a high hydrolysis rate and should meet the requirements of your installation. Another aspect to consider is the air supply in the combustion furnace.

The COS generated as a by-product of side reactions in the combustion furnace needs to be decomposed; one condition for this is that the temperature at the reactor inlet must be above 326 degrees. Another condition is the presence of a titanium-based catalyst – it isn’t necessary to replace the entire catalyst; 300 mm of titanium-based catalyst placed at the top is sufficient. Of course, it also depends on the specific process being used. If it’s the Super Claus process with 99.5% efficiency, or if there’s a Scott unit for exhaust gas treatment, then this titanium-based catalyst isn’t necessary; hydrogenation can be used directly to convert COS into hydrogen sulfide. Steaming is not a viable method; it only provides temporary relief, does not address the root cause, and can also cause catalyst water poisoning. This post was last edited by minjie061 on 2009-4-19 22:58.]

In my opinion, the high level of COS in the exhaust gases is caused by an insufficient amount of H2 during the hydrogenation reaction. The solution is to use more H2 vapor; the impact of this vapor on the catalyst depends on whether it is superheated or saturated. In the case of saturated vapor, certain substances will condense within the catalyst, which has an effect on it； Overheated steam is mainly a matter of temperature; if the temperature is appropriate, this won’t happen

COS is primarily produced in reaction reactors； Possible reasons for high COS levels in exhaust gas: 1. Low temperature in the primary converter ； 2. No hydrolysis catalyst or catalyst deactivation. 3. The temperature control in the hydrogenation reactor is too low, or the catalyst is deactivated. 4. The hydrocarbon content in the raw material is too high, but the furnace temperature is not high. Personally, I don’t recommend using steam. This post was last edited by adsl121 on 2009-4-20 at 13:35.]

COS is primarily generated through reactions, in which H2S + CO can also produce COS + H2O. The presence of a certain amount of water vapor shifts the reaction to the left, reducing the COS concentration; it is best to remove most of the H2S first, then add a COS hydrolysis catalyst, and subsequently remove the H2S