Double combustion oxygen enhanced sulfur recovery process

Abstract

A feed gas stream containing at least 60% by volume of hydrogen sulphide is burnt in a first combustion region to form water vapor and sulphur dioxide. Oxygen is employed to support combustion is the region. Thermal reaction then takes place in a thermal reaction region between hydrogen sulphide and sulphur dioxide to form sulphur vapor and water vapor. The resulting gas mixture is then cooled and sulphur vapor is extracted in a condenser. The gas mixture then passes into a second combustion region in which a further portion of the hydrogen sulphide is burnt in the presence of oxygen to form further sulphur dioxide and to adjust the mole ratio of hydrogen sulphide to sulphur dioxide to about 2:1. Further reaction between hydrogen sulphide and sulphur dioxide may be conducted in a further thermal reaction region and in catalytic reactors with further sulphur extraction in further condensers. The mole ratio of hydrogen sulphide to oxygen entering the first combustion region per unit time is greater than 2:1 and the mole ratio of hydrogen sulphide to fluid(s) (if any) other than oxygen being introduced into the first combustion region is greater than 3:2 and preferably greater than 4:1. By using substantially pure oxygen to support combustion of the hydrogen sulphide, a relatively large flow rate of feed gas mixture may be handled in a plant of given size.