Double combustion oxygen enhanced sulfur recovery process

Apparatus for recovering sulphur from a feed gas stream comprising hydrogen sulphide, comprising means for burning less than 33 mole percent of the hydrogen sulphide content of the feed gas stream in a first combustion region to form water vapour and sulphur dioxide;

• means for introducing oxygen into the combustion region to support the combustion of the hydrogen sulphide;
• a thermal reaction region, in association with the combustion region, for reacting unburnt hydrogen sulphide with said sulphur dioxide to form sulphur vapour and water vapour;
• first means for extracting the thus formed sulphur vapour;
• downstream of said extracting means at least one catalytic reaction region for reaction between hydrogen sulphide and sulphur dioxide to form further water vapour and sulphur vapour;
• second means for extracting said further sulphur vapour, and means for adjusting the mole ratio of said hydrogen sulphide to sulphur dioxide to bring it to the stoichiometric value or one approximating thereto, said adjusting means comprising a second combustion region upstream of said at least one catalytic region and additionally including a by-pass conduit having an inlet communicating with the outlet for gas of the first sulphur extraction means, and an outlet terminating downstream of the second combustion region and upstream of, in, or downstream of the second thermal reaction region, and wherein there is no means for recycling gas to said first combustion region from downstream of said thermal reaction region.

In a process for the production of sulfur by reaction of hydrogen sulfide and sulfur dioxide wherein a feed of hydrogen sulfide is oxidized in part to sulfur dioxide to form reactants which yield sulfur by the modified catalytic Claus reaction, the improvement which comprises:

• (a) introducing to a first combustion zone at least a portion of hydrogen sulfide rich gas stream containing at least about 10% by volume hydrogen sulfide and a first oxygen rich gas containing at least about 30% by volume oxygen in a proportion to achieve by combustion a first sulfur dioxide containing product gas stream at a combustion flame temperature of from about 1000.degree. F. to about 3600.degree. F.;
• (b) cooling the first product gas stream to a temperature from about 240.degree. F. to about 3000.degree.;
• and
• (c) introducing the cooled first product gas stream to at least a second combustion zone with additional oxygen rich gas stream containing at least about 30% by volume oxygen to combust additional hydrogen sulfide and yield a second sulfur dioxide containing product gas stream at a combustion flame temperature of from about 1000.degree. F. to about 3600.degree. F., the amount of hydrogen sulfide and oxygen fed to the combustion zones being proportioned to provide on completion of combustion a gas stream having a mole ratio of hydrogen sulfide to sulfur dioxide of about 2:1 for feed to a catalytic Claus convertor to achieve formation of sulfur by reaction of residual hydrogen sulfide with sulfur dioxide formed during combustion in the combustion zones.