High pressure reduction-oxidation desulfurization process
An improved process for reduction-oxidation desulphurization uses an oxidizer operating at a pressure greater than the absorber where a liquid reduction-oxidation catalyst solution contacts a sulfur-containing gas feed stream.
1. A process for continuously removing hydrogen sulfide from a gaseous stream comprising the following steps in combination:
a. providing a feed stream containing hydrogen sulfide to an reduction-oxidation process;
b. contacting the feed gas stream with a chelated metal catalyst in an absorber operating a pressure P 1 that is greater than 100 psig to produce a first stream of hydrogen sulfide-free gas and a second stream comprising elemental sulfur and chelated metal catalyst solution;
c. removing the first stream from the process;
d. providing an oxidizer operating a pressure P 2 , where P 2 ≧P 1 +5 psi;
e. directing at least a portion of the second stream from step b. to the oxidizer;
f. introducing a pressurized, oxygen containing gas stream into the oxidizer such that the oxygen diffuses through and contacts the second stream; and
g. separating elemental sulfur from the chelated metal catalyst solution in the oxidizer and removing the sulfur from the reduction-oxidation process.
2. The process of claim 1 where the oxygen containing gas is introduced into the oxidizer at a pressure P 3 , where P 3 ≧P 2 .
3. The process of claim 1 where the oxygen containing gas introduced into the oxidizer is used to maintain the pressure differential between the oxidizer and the absorber.
4. The process of claim 1 further comprising the absence of a flash drum in fluid communication with the absorber and the oxidizer.
5. The process of claim 1 where the oxidizer pressure P 1 is maintained by the combination of high pressure air injection and a differential pressure controller that monitors the absorber pressure P 2 and operates a pressure control valve on an oxidizer vent line.