Graded-bed system for improved separations
AssigneeMobil Oil Corporation
InventorsJ. Scott Buchanan, Khushrav E. Nariman
Life of this patent
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Abstract
A method and system useful for the removal of contaminants such as sulfur oxides from waste gas streams using a graded-bed system is disclosed. The graded-bed system uses beds with solid sorbents of two or more particle sizes in separate sections of the bed. In one embodiment, the solid sorbents are arranged so that the larger sorbent particles are disposed in the entrance region of the graded-bed system. In operation, a waste gas stream is passed over and through the solid sorbents so that contaminants, such as sulfur oxides and/or nitrogen oxides are adsorbed. The sorbent bed is then contacted with a reducing gas to desorb the sulfur oxides.
Claims21
A process for adsorption of sulfur oxides from a waste gas which is substantially free of entrained particulate matter, said process comprising the steps of
- (a) contacting a waste gas which is substantially free of entrained particulate matter, which waste gas contains sulfur oxides with a solid adsorbent under conditions effective to promote capture of sulfur oxides from the waste gas onto the solid adsorbent to thereby produce a treated waste gas and a solid adsorbent having sulfur compounds thereon, the solid adsorbent having more than two particle sizes ranging from larger particles to smaller particles, the waste gas contacting the larger particles before contacting the smaller particles;
- (b) directing the treated waste gas from the solid adsorbent;
- (c) terminating contact between the waste gas and the solid adsorbent after the solid adsorbents have become substantially loaded with sulfur oxides as evidenced by breakthrough of increased amounts of sulfur oxides into the treated waste gas;
- (d) regenerating the solid adsorbent by contacting it with a reducing gas, under conditions effective to desorb at least a portion of the sulfur compounds thereon, thereby producing an offgas stream and a desulfated solid adsorbent;
- (e) directing the offgas stream from the solid adsorbent to a downstream sulfur recovery process;
- and
- (f) returning the desulfated solid adsorbent into contact with the waste gas.
A process for adsorption of sulfur oxides from a substantially particulate-free waste gas, said process comprising the steps of
- (a) contacting a substantially particulate-free waste gas comprising sulfur oxides with a solid adsorbent under conditions effective to promote adsorption of sulfur oxides from the waste gas onto the solid adsorbent to thereby produce a treated waste gas and a solid adsorbent having sulfur compounds thereon, the solid adsorbent having a first average particle size and a second average particle size, the first particle size being larger than the second particle size, the waste gas contacting the larger particles before contacting the smaller particles;
- (b) directing the treated waste gas from the solid adsorbent;
- (c) terminating contact between the waste gas and the solid adsorbent after the solid adsorbents have become substantially loaded with sulfur oxides as evidenced by breakthrough of increased amounts of sulfur oxides into the treated waste gas;
- (d) regenerating the solid adsorbent by contacting it with a reducing gas, under conditions effective to desorb at least a portion of the sulfur compounds thereon, thereby producing an offgas stream and a desulfated solid adsorbent;
- (e) directing the offgas stream from the solid adsorbent to a downstream sulfur recovery process;
- and
- (f) returning the desulfated solid adsorbent into contact with the waste gas.
A process for adsorption of sulfur oxides from a substantially particulate-free waste gas, said process comprising:
- (a) providing a reaction vessel comprising a container having an entrance region and an exit region, a first solid adsorbent disposed in a first bed inside said container in the area of said entrance, a second solid adsorbent having a particle size smaller than that of said first solid adsorbent, said second solid adsorbent disposed in a second bed inside said container;
- (b) passing a substantially particulate-free waste gas stream comprising sulfur oxides into said reaction vessel through said entrance region;
- (c) successively contacting said waste gas stream with said first and second solid adsorbents at a pressure and temperature sufficient to promote adsorption of sulfur oxides onto said solid adsorbents and to thereby produce a treated waste gas;
- (d) passing said treated waste gas stream from said reaction vessel through said exit region;
- (e) ceasing adsorption of sulfur oxides on said first and second solid adsorbents after said solid adsorbents have become substantially loaded with sulfur oxides as evidenced by breakthrough of increased amounts of sulfur oxides into the treated waste gas stream;
- (f) regenerating the first and second solid adsorbents by contacting them with a reducing gas, at a pressure and temperature wherein said sulfur oxides are desorbed from said solid adsorbents into an offgas stream;
- and
- (g) passing said offgas stream from said reaction vessel through said exit region into a downstream sulfur recovery process.
Dependencies are inferred from the claim text.