How does the hydrogen concentration required for hydrogenation of sulfur-containing exhaust gases affect the difficulty of controlling SO2 emissions from incinerator exhausts?

The general control range is 2-5%

This answer is not accurate; 2-7% refers to the excess amount of hydrogen in the exhaust gases after hydrogenation. Based on the literal wording of the question, it is asking about the concentration of hydrogen introduced into the hydrogenation system. In refineries, there are generally two types of hydrogen sources: 1. Reforming hydrogen ； 2. Hydrogen production: the concentration of the former is 85–92%, while the hydrogen concentration of the latter is over 95%. The hydrogenation system in the sulfur recovery unit has low requirements regarding hydrogen concentration; it is sufficient to ensure that the excess hydrogen content in the exhaust gas after hydrogenation is between 2-7%. The problem is that the lower the hydrogen concentration in hydrogen gas, the higher the content of other impurities, and these impurities in hydrogen gas are usually hydrocarbons. An excessive amount of hydrocarbons entering the hydrogenation reactor will react with hydrogen sulfide to form organic sulfur, affecting the efficiency of the absorption tower and the sulfur dioxide emissions in the exhaust gases. Therefore, it is recommended that if high-purity hydrogen is available, it should be used; or hydrogen with a lower hydrocarbon content should be utilized.

Don’t throw it away~ I’m almost killed by the bricks already;P

Putting the hydrogen concentration aside, the proportion of hydrogen in the output should be at least 4; this is mainly to prevent various elemental sulfur compounds from clogging trays or filters and other equipment downstream, thereby causing pressure buildup in the system

Insufficient hydrogen, sulfur dioxide penetration, tower blockage; severe excess of hydrogen may cause the exhaust furnace to overheat.