Refineries are being forced to refine sour crude oil stocks which are less expensive than sweet sulfur free crude oil stocks to maintain profitability.
It is imperative that the sulfur present in sour crude is removed on the front end of the refining process; as sulfur bearing crude is corrosive and will produce hydrogen sulfide which will cause stress corrosion cracking throughout the balance of plant and is lethal. The sulfur captured in the sulfur recovery unit is a bi-product and can be sold by the refinery or blended to manufacture sulfuric acid.
