Acid gas burner residence time
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The residence time in several of the acid gas combustion furnaces encountered was generally 1.5 seconds; however, one furnace was found to have a residence time of 4–5 seconds (of course, the H2S concentration there was low, around 35%). There’s no real need for such a long residence time. Additionally, what is an appropriate length-to-diameter ratio for the furnace, and how is that determined?
Currently, in both domestic and international design practices, the dwell time is usually set at 1-2 seconds.
Chemical reactions take place very rapidly inside the combustion furnace; generally, the entire reaction is completed within 1 second. The design typically sets the dwell time at 1-2 seconds.
The residence time of acidic gases in the combustion furnace is generally between 0.7 seconds and 1.5 seconds. If this residence time is too short, the acidic gases cannot react sufficiently; if it is too long, the likelihood of side reactions increases. Therefore, the residence time is determined based on the impurity components of the acidic gases and the conversion rate of the main reaction.
What is a suitable length-to-diameter ratio for a furnace, and how is it determined?
In China, it is 1–2.5 seconds; abroad, it is less than 1 second
Does a residence time of 4 to 5 seconds indicate a problem with the design?
The length-to-diameter ratio is generally greater than or equal to 3
For sulfur recovery units, theoretically, a longer residence time is indeed beneficial for complete ammonia combustion. However, since the reaction inside the reactor is completed in an instant, a residence time of 1-2 seconds is basically sufficient; extending it further would require increasing the length of the reactor, and it would not significantly improve the conversion efficiency. This post was last edited by Clauspolunit on 2009-4-7 16:10]