Mobil Oil Corporation

Exxonmobil Oil Corporation

Joseph F Sodomin, Iii

Gerald J Teitman

John Scott Buchanan

Mark F Mathias

David Lawrence Stern

Scott A Stevenson

David L Johnson

Amos A Avidan

Raghu K Menon

A process and system is disclosed for removing sulfur from tail-gas emitted from a Claus sulfur recovery process. First, the tail-gas is oxidized so as to convert sulfur therein to sulfur oxides. Oxidized tail-gas is directed into an absorber where a solid absorbent absorbs substantially all the sulfur oxides thereon. After allowing sufficient time for a desired amount of sulfur oxides to be absorbed, absorption is ceased. Next, the solid absorbent containing the absorbed sulfur oxides is contacted with a reducing gas so as to release an off gas containing hydrogen sulfide and sulfur dioxide. Upon releasing sulfur from the solid absorbent, the solid absorbent is regenerated and redirected into the absorber. Sulfur in the off gas emitted by regeneration is concentrated to an extent sufficient for use within a Claus sulfur recovery process for conversion to elemental sulfur. By combining this process with a Claus sulfur recovery process, sulfur dioxide emissions can be reduced to less than about two parts per million.

Process and system for desulfurizing a gas stream

Removing sulfur oxide, carbon monoxide and nitrogen oxide in a flue gas stream by combusting fuel in the combustor with a reduced amount of oxygen to convert all sulfur-containing species in the flue gas stream to sulfur oxide, and to partially convert carbon monoxide therein to carbon dioxide, thus forming a sulfur oxide enriched gas stream having between at least about 500 ppm carbon monoxide and a consequential reduced amount of nitrogen oxide. The sulfur oxide enriched gas stream is contacted with a solid adsorbent bed for adsorbing the sulfur oxides in the form of inorganic sulfates and/or sulfur oxides. The solid adsorbent contains a catalytic oxidation promoter for oxidizing the carbon monoxide gas stream to carbon dioxide, thus forming a sulfur oxide and carbon monoxide depleted stream with the consequential reduced amount of nitrogen oxide for disposal. The adsorbent bed is then contacted with a reducing gas stream for regenerating the adsorbent bed to form a hydrogen sulfide and/or sulfur dioxide bearing stream.

Removing SOx, CO and NOx from flue gases

Removing sulfur oxide and carbon monoxide in a flue gas stream by combusting fuel in the combustor with a reduced amount of oxygen to partially convert carbon monoxide therein to carbon dioxide and sufficient to convert all sulfur-containing species in the flue gas stream to sulfur oxide and thus form a sulfur oxide enriched gas stream having between at least about 500 ppm carbon monoxide. The sulfur oxide enriched gas stream is contacted with a solid adsorbent bed for adsorbing the sulfur oxides in the form of inorganic sulfates and/or sulfur oxides. The solid adsorbent contains a catalytic oxidation promoter for oxidizing the carbon monoxide gas stream to carbon dioxide, thus forming a sulfur oxide and carbon monoxide depleted stream for disposal. The adsorbent bed is then contacted with a reducing gas stream for regenerating the adsorbent bed to form a hydrogen sulfide and/or sulfur dioxide bearing stream.

Removing SO.sub.x, NO.sub.X and CO from flue gases

A multi-bed process of removing sulfur oxides and/or other combustible sulfur-containing compounds from a gas stream including combusting the other combustible sulfur-compounds when present in the gas stream with air or oxygen to convert such sulfur-containing compounds to sulfur oxide and form a sulfur oxide enriched gas stream. The sulfur oxide enriched gas stream is contacted with first and second serially connected solid adsorbent beds for adsorbing the sulfur oxides in the form of inorganic sulfates and/or sulfur oxides. A third adsorbent bed is contacted with a reducing gas stream to regenerate the bed by reducing the retained inorganic sulfates and/or sulfur oxides to hydrogen sulfide and/or sulfur dioxide, to thereby form a hydrogen sulfide and/or sulfur dioxide bearing stream. The feeds to each of the beds are realigned to place the second and third beds in series with the sulfur oxide and/or sulfur dioxide enriched stream being fed to the second bed and to place the first bed in a regenerative mode. Thereafter, the foregoing steps are repeated whereby each of the three beds are sequentially placed in an initial bed mode in the series, a regenerative mode, and a second bed mode in the series.

Desulfurizing a gas stream

Oxides of nitrogen (NO.sub.x) emissions from an FCC regenerator are reduced by forcing the regenerator to operate between full and partial CO burn mode. Operating with less than 1 mole % O2 and up to 1 or 2% CO in the flue gas creates conditions which oxidize nitrogen compounds in coke on spent catalyst to NOx, and simultaneously convert NOx in the regenerator to nitrogen. A downstream CO boiler can burn this low CO flue gas without producing large amounts of NOx. Most NOx emissions can be eliminated. An apparatus, with the regenerator air:coke ratio controlled by both CO and O2 analyzers monitoring regenerator flue gas, is also disclosed.

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Landenberg, PA, United States of America

Joseph F Sodomin, Iii