Hydrogen sulfide amine strippers

A portion of the heat obtained from this reaction is also recovered as steam which, together with that produced by the sulfur-burning boiler, is frequently sufficient to heat the stripper of the associated Girbotol (amine scrubber) plant. The net overall Claus chemistry, thus, involves oxidation of hydrogen sulfide with air to yield sulfur and water (Eq. 9.20). 

The gas leaving the hydrogenation reactor is first cooled in a waste heat boiler to about 170°C and then in a quench cooler to approximately 35°C. The quenching operation uses circulating water from which the heat is removed in a cooler. Unlike the Sulfreen process described above, this process produces condensate as the gas is cooled below the steam dew point this condensate has to be withdrawn from the water loop and fed to a stripper to remove H2S. A blower delivers the almost dry gas from the quench cooler to an absorber to eliminate the hydrogen sulfide by means of an amine wash liquor. 

The additive recovery column is basically a stripper to remove hydrogen sulfide and light hydrocarbons, primarily ethane and propane, from the circulating additive stream. Excess C4+ hydrocarbons that accumulate in the stripped additive are removed as net product, which can be combined with the overhead product as indicated in the flow diagram or handled separately. When the plant feed contains hydrogen sulfide, this will appear in the overhead of the additive recovery column and may be removed from this stream by amine treating (not shown on the diagram). 

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