Natural gas that contains sulfur is called “sour gas” because sulfur has a strong rotten-eggs odor. The process of removing sulfur from natural gas is therefore called “sweetening.”
Sulfur in natural gas occurs as hydrogen sulfide, which must be removed because it is toxic when inhaled and is highly corrosive to pipeline walls. Also, if recovered in sufficient quantities, hydrogen sulfide can be neutralized to yield pure, marketable sulfur.
The most common sweetening process is similar to glycol dehydration. In this instance, the absorbent liquid is a solution of sulfur-attracting amines. The cap over the inlet pipe forces gas to pass through the amine liquid, which captures the sulfur molecules while the natural gas bubbles out of the liquid to be collected from above.»next