Regarding the issue of the first sulfidation of the H-catalyst in exhaust gas

Our plant uses process gas rich in H2S from the Claus reaction, with the H2S content controlled at 0.24 (v%). In fact, pre-sulfidation with acid gas can also be used, but it is necessary to analyze the composition of the feed gas and control the levels of H2S, NH3, H2O, etc. in it.

In terms of plant design, either option is considered acceptable; Zhenhai successfully used acidic gas for pre-sulfurization, and it seems that some publicity was also done regarding this. It is of course best to use acidic gas for direct presulfurization, as it takes less time, allows for rapid startup, and has a minimal impact on the environment. But be sure to pay attention to the components of acidic gases! ! ! Since pre-vulcanization is carried out using process gas, it’s not very clear. Isn’t there a comrade who specializes in suppressing sea disturbances in the hall? I hope to introduce them to everyone. To set the record straight!

Adjust the air-fuel ratio of the sulfur production combustion furnace using process gas, so as to bring the H2S/SO2 ratio in the sulfur production exhaust gases to 4–6/1; if acidic gas is used for sulfidation, a H2S concentration of 1–2% (v) will suffice. It depends on the design of one’s own process

Either pre-sulfurization of Claus off-gases or acidic gases can be used; the key is which option is recommended by the design firm and the catalyst supplier.

Acidic gases have a high hydrogen sulfide content and no sulfur dioxide; they are effective for pre-sulfurization； If pre-vulcanization is carried out using process gas, it is necessary that the hydrogen analyzer and ratio meter are accurate; otherwise, there is a risk of blocking the quenching system

If there is Claus off-gas, it is best to use this gas for pre-vulcanization, as this makes the entire pre-vulcanization process easier to control; good results can be achieved by maintaining an air-to-fuel ratio of 4–6:1 in the acidic gas combustion furnace. If direct pre-vulcanization with acidic gas is used, it is necessary to mix the acidic gas into an inert gas, keep the hydrogen sulfide concentration below 1%, and carry out pre-vulcanization gradually. For specific details, please consult the catalyst manufacturer.

Pre-vulcanization using CLAUS exhaust gas

By adjusting the set values, the inlet temperature of the Scott reactor is controlled to keep the reactor bed temperature between 240–250°C. The hydrogen content in the circulating gas is maintained at around 5–6% (V). Analyze the composition of the acidic gas to ensure that its ammonia content is less than 1% (V) and its medium hydrocarbon content is less than 3% (V). Slowly open the valve allowing acidic gas to enter the Scott furnace; analyze the hydrogen sulfide content in the gas entering the reactor to keep this level below 1% (V). Once hydrogen sulfide gas enters the Scott reactor, the cobalt/molybdenum catalyst begins to undergo pre-sulfidization. By analyzing the hydrogen sulfide content in the gas entering the Scott reactor, it is possible to determine the hydrogen sulfide level in the gas and thus the degree of pre-sulfidization of the catalyst. When the hydrogen sulfide concentrations in the gas entering and leaving the reactor are similar, it indicates that the pre-sulfidization of the catalyst is complete. Raise the reactor bed temperature to 300°C and maintain this temperature for 4 hours; thereafter, lower the inlet temperature of the reactor to 280°C and close tightly the valve allowing acidic gas to enter the Scott furnace. Catalyst presulfurization is complete. The acidic pipeline is purged with nitrogen once, after which the valves at both ends of the pipeline are closed tightly