Continuous desulfurization process based on metal oxide-based regenerable sorbents

A continuous operation desulfurization system for desulfurizing a gas stream containing reduced sulfur species at concentration in a range of from about 5 to about 5000 ppmv, wherein said reduced sulfur species is hydrogen sulfide (H2S), carbonyl sulfide (COS), carbon disulfide (CS2), thiol with four or less carbon atoms, disulfide with four or less carbon atoms, or a mixture of two or more of the foregoing reduced sulfur species, said system comprising:

• at least two primary adsorbent beds of desulfurization sorbent selective for said reduced sulfur species, constructed and arranged in relation to one another so that each of said adsorbent beds in operation undergoes a cyclic alternating and repeating sequence of (i) onstream desulfurization operation including contacting of said gas stream with the sorbent in the sorbent bed to produce a sulfur-reduced gas stream, and (ii) offstream regeneration operation including (a) contacting the sorbent in the sorbent bed with oxygen-containing regeneration gas to remove adsorbed sulfur species to produce a sulfur dioxide-containing regeneration gas, and optionally one or both of (b) heating of the sorbent in the sorbent bed and (c) purging of the adsorbent bed;
• a sulfur dioxide conversion unit constructed and arranged to process the sulfur dioxide-containing regeneration gas to remove sulfur dioxide therefrom and produce sulfur dioxide-depleted regeneration vent gas;
• valved flow circuitry constructed and arranged to selectively:
• (1) connect an onstream one of said at least two adsorbent beds of desulfurization sorbent in gas-receiving relationship with a source of the gas stream containing reduced sulfur species;
• (2) connect an offstream one of said at least two adsorbent beds of desulfurization sorbent in gas-receiving relationship with a source of the oxygen-containing regeneration gas;
• (3) flow the sulfur dioxide-containing regeneration gas from the offstream one of said at least two adsorbent beds of desulfurization sorbent to said sulfur dioxide conversion unit, and discharge sulfur dioxide-depleted regeneration vent gas from said sulfur dioxide conversion unit;
• and
• a controller constructed and arranged to operate valves of the valved flow circuitry in response to at least one of (A) a monitored system operating condition, and (B) a cycle time program, so that each one of said at least two adsorbent beds of desulfurization sorbent cyclically, alternatingly and repetitively undergoes said sequence of (i) onstream desulfurization operation and (ii) offstream regeneration operation, in the continuous operation of the system.