Combustion furnace, acidic gas distribution~
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Our process is the super Claus process: part of the acidic gases goes into the main burner, while another part enters the rear part of the main combustion chamber; after combining and reacting there, they pass through the waste heat boiler before entering the Claus reactor. How do you allocate the acidic gases going to the main burner and those going to the combustion chamber? What factors are mainly considered?
On our end, we mainly consider the temperature of the combustion furnace ； Klaus stage reaction efficiency (H2S/SO2 ratio) ； Temperature rise in the rear catalytic oxidation reactor (remaining H2S amount). The numerical values fluctuate greatly; is there any approximate reference value for allocation?
This mainly depends on the temperature inside the furnace.
We allocate 20-30% of the total amount to later.
What temperature do you usually keep in the furnace? Should Klaus’ H2S/SO2 ratio be taken into consideration?
Basis? Based on the amount provided in the process package, I think the main factor to consider is temperature; the more air introduced from behind, the greater the excess air flow at the front, and thus the higher the temperature. But too much diversion cannot be allowed, probably because mixing may not be adequate, and the residence time in the furnace is too short, resulting in an insufficient conversion rate. Temperature control depends on whether you are burning ammonia or not; why keep it so high if no ammonia is being burned? For ammonia burning, at least 1250 is required, with 1300 or more being preferable. The amount of diversion has nothing to do with the H2S/SO2 ratio, since the total air supply remains constant.
According to the data provided in our process package, more sulfur is generated in the furnace than in the first stage of the Claus process. When there is a lack of oxygen, H2S directly forms some sulfur; do H2S and SO2 also produce large amounts of sulfur through reactions in the furnace?
The disagreement may lie in the understanding of the term “peroxide”. In fact, for zoned combustion of acidic gases, both the total amount of acidic gases and the total amount of air remain constant. As the acidic gases are diverted while the air is not, this leads to localized hyperoxia in the main flame zone, thereby increasing the temperature of the main flame. But overall, the air distribution has not increased. H2S is directly converted into elemental sulfur; according to the book, some of the H2S is converted into SO2 first, and then H2S and SO2 combine to form sulfur. However, we can consider that in the furnace, 2/3 of the H2S is directly transformed into elemental sulfur.
To be precise, it is necessary to ensure stable and safe combustion of the burner, which should be determined based on the H2S concentration in the feed gas； Generally speaking, a higher concentration results in more flow into the burner, while a lower concentration leads to less flow. In any case, it is necessary to maintain stable flame conditions in the burner without allowing the temperature to become too high ； Generally, the H2S concentration in the feed gas does not fluctuate much and remains relatively stable, so operating according to the process specifications is sufficient. For sulfur recovery, most of the sulfur should be generated in the sulfur production furnace.
Why does \"more flow enter the burner when the concentration is high, and less flow enters when the concentration is low\"? If, in order to maintain stable burner flames while keeping the temperature from becoming too high, a higher concentration is required, shouldn’t less fuel be supplied? Prevent overheating~:)