IRON SPONGE TECHNOLOGY

Iron Sponge Process is based on the reaction of hydrogen sulfide with iron oxide in which the gas is passed through a bed of wood chips impregnated with iron oxide. The process scavenges hydrogen sulfide and organic sulfur compounds (mercaptans) from gas streams through reactions with the solid-based chemical adsorbent.

In the process, the sour gas is passed down through the bed. In the case where continuous regeneration is to be used, a small concentration of air is added to the sour gas before it is processed. The air serves to continuously regenerate the iron oxide, which has reacted with hydrogen sulfide, which serves to extend the on-stream life of a given tower, but probably serves to decrease the total amount of sulfur that a given weight of bed will remove. In a two-vessel process, one of the vessels would be on stream removing hydrogen sulfide from the sour gas, while the second vessel would either be in the regeneration cycle or having the iron sponge bed replaced.

The process is usually best applied to gases containing low to medium concentrations (300 ppm) of hydrogen sulfide or mercaptans. This process tends to be highly selective and does not normally remove significant quantities of carbon dioxide. As a result, the hydrogen sulfide stream from the process is usually high purity.