US 5,514,351 AGranted

Desulfurizing tailgas from sulfur recovery unit

AssigneeMobil Oil Corporation

InventorsJohn S. Buchanan, Jagannathan N. Iyengar, David L. Stern

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Abstract

With sufficient oxygen but with no added fuel gas, recovering sulfur from a gas stream containing hydrogen sulfide by oxidizing the gas stream with heat exchange from heat generated in a thermal converter section of a sulfur recovery unit to convert the hydrogen sulfide in the gas stream to sulfur oxide, and thus form a sulfur oxide enriched gas stream. The sulfur oxide enriched gas stream is contacted with a solid adsorbent bed to extract the sulfur oxides and retain them as sulfur compounds, thus forming a sulfur oxide depleted gas stream. The adsorbent bed is then contacted with a reducing gas stream to reduce the retained sulfur compounds to hydrogen sulfide and/or sulfur dioxide and thereby form a hydrogen sulfide and/or sulfur dioxide bearing stream. Sulfur is recovered from the hydrogen sulfide and/or sulfur dioxide bearing stream, and the sulfur oxide depleted gas stream maybe sent to an incinerator or vented through a stack.

Claims28

Dependent claims

A method of recovering sulfur from a gas stream formed by a tailgas stream from a sulfur recovery unit containing hydrogen sulfide comprising the steps of:

(a) adding air or oxygen to said hydrogen sulfide containing gas stream;
(b) after step (a) and with no added fuel gas, oxidizing said hydrogen sulfide containing gas stream in a indirect gas-to-gas heat exchanger, said heat exchanger being heated with heat generated in a thermal converter section of a sulfur recovery unit to convert the hydrogen sulfide in said hydrogen sulfide containing gas stream to sulfur oxide, the air or oxygen being added in an amount to support conversion of all of the hydrogen sulfide in said hydrogen sulfide containing gas stream to sulfur oxide, and thereby form a sulfur oxide enriched gas stream;
(c) contacting said sulfur oxide enriched gas stream with a solid adsorbent bed for adsorbing thereon the sulfur oxides in the form of inorganic sulfates or sulfur oxides or combinations thereof, and thereby form a sulfur oxide depleted stream;
(d) contacting said adsorbent bed with a reducing gas stream to regenerate said adsorbent bed by reducing said retained inorganic sulfates or sulfur oxides or combinations thereof to hydrogen sulfide and/or sulfur dioxide, and thereby form a hydrogen sulfide and/or sulfur dioxide bearing stream;
and
(e) recovering sulfur from said hydrogen sulfide and/or sulfur dioxide bearing stream.

3 more elements

A method of desulfurizing a hydrogen sulfide containing tailgas stream from an elemental sulfur recovery unit which comprises (1) a thermal converter section including a furnace for combusting a refinery gas stream having a high concentration of hydrogen sulfide to convert at least about one-third of the hydrogen sulfide therein to sulfur dioxide and to combust hydrocarbon gas therein, and a waste heat boiler powered by said furnace for making high pressure steam, and (2) a plurality of serially connected stages downstream of said thermal converter section, each stage including a catalytic reactor for converting hydrogen sulfide and sulfur dioxide in the combusted refinery stream to sulfur and a condenser for recovering sulfur, with the condenser in the last stage providing said tailgas stream;

said method comprising the steps of:
(a) adding air or oxygen to said tailgas stream;
(b) after step (a) and with no added fuel gas, oxidizing said tailgas stream at a temperature of from about 900.degree. F. to about 1400.degree. F. in an indirect gas-to-gas heat exchanger, said heat exchanger being heated with heat generated in said waste heat boiler for converting all of the hydrogen sulfide in said tailgas stream to sulfur oxide, the air or oxygen being added in an amount to support conversion of the hydrogen sulfide in said tailgas stream to sulfur oxide and thereby form a sulfur oxide enriched gas stream;
(c) contacting said sulfur oxide enriched gas stream with a solid adsorbent bed for adsorbing thereon the sulfur oxides in the form of inorganic sulfates or sulfur oxides or combinations thereof, and thereby form a sulfur oxide depleted stream;
(d) heat exchanging said sulfur oxide depleted stream to recover at least 70% of the steam generating heat lost by said waste heat boiler during heat exchange in step (b);
(e) contacting said adsorbent bed with a reducing gas stream to regenerate said adsorbent bed by reducing said retained inorganic sulfates or sulfur oxides or combinations thereof to hydrogen sulfide and/or sulfur dioxide, and thereby form a hydrogen sulfide and/or sulfur dioxide bearing stream;
and
(f) passing said hydrogen sulfide and/or sulfur dioxide bearing stream to said thermal converter section for recovering sulfur therefrom.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/186,934Filed 27 Jan 1994 · continuation in part
Priority: 15 Apr 1992
Granted: 7 May 1996
Term ends: Not estimatedThe source records don’t support an estimate.

Classification18 codes

B01D 53/12
With dispersed adsorbents: according to the "fluidised technique"
B01D 53/04
By adsorption, e.g. preparative gas chromatography: with stationary adsorbents
B01D 53/485
Sulfur compounds: containing only one sulfur compound other than sulfur oxides or hydrogen sulfide
B01D 53/508
Sulfur oxides: by treating the gases with solids

Family

Serial868,432Parent of this continuation · filed 15 Apr 1992
Serial877,936Parent of this continuation-in-part · filed 4 May 1992
Serial63,473Parent of this continuation-in-part · filed 19 May 1993
US 5,292,492 AParent of this continuation-in-part
US 5,229,091 AParent of this continuation
US 5,514,351 AThis patent

From the US filing history. Foreign family members aren’t listed.