Shell Oil Comapny

Shell California Production Inc.

Norman C Samish

John E Gwyn

Gregory L Johnson

Diana M Altrichter

Jack B Pohlenz

The invention is a method for reduction of sulfur trioxide in flue gases which includes (a) combusting air and petroleum coke in a combustion zone to produce a particulates, sulfur trioxide, and sulfur dioxide-containing combustion product gas; (b) passing the combustion product gas from step (a) to a dry electrostatic precipitator for removal of particulates and recovering the combustion product gas substantially free of particulates, or alternatively rearranging the steps so so that step 'b' follows steps 'c' and 'd'; (c) admixing particulates with the combustion product gas from step (b), to produce a first mixture; (d) passing the first mixture from step (c) to an air preheater for cooling the first mixture and heating the air for combustion with the petroleum coke, wherein the sulfur trioxide in the first mixture condenses on the particulates, to produce a second mixture containing combustion product gas containing sulfur trioxide condensed on particulates and sulfur dioxide; (e) passing the second mixture from step (d) to a wet scrubber for removal of substantially all of the sulfur dioxide, sulfur trioxide, and particulates, to produce a combustion product gas substantially free of sulfur dioxide, sulfur trioxide, and particulates; and (f) passing the combustion product gas substantially free of sulfur dioxide, sulfur trioxide, and particulates from step (e) to a stack for release to the atmosphere.

Method for reduction of sulfur trioxide in flue gases

A process is disclosed in which a flue gas from a coal fired burner is treated in a dry phase to remove both NO.sub.x and SO.sub.x which includes SO.sub.2 and SO.sub.3. This invention provides for use of an absorbent comprising of fly ash, calcium oxide and a hydrated sulfate of calcium to remove the SO.sub.2 and/or SO.sub.3 component while also incorporating either a high carbon ash, ash derived from a high-vanadium residual oil, iron oxide or iron oxides to remove NO.sub.x. Process conditions comprise a temperature in the range of 200.degree. C. to 450.degree. C.

Removal of SO.sub.x and NO.sub.x gases from flue gas by dry absorption

A method of removing sulfur oxides from flue gas produced by the combustion of a fuel to produce a flue gas containing sulfur oxides and water comprising contacting the moist flue gas with hydrated alkaline earth metal hydroxide particles having a temperature sufficiently low to condense the water vapor present in the flue gas onto the particles and recovering a flue gas reduced in sulfur oxides.

Removal of sulfur oxides from flue gas

This process discloses a reduction in the content of ammonia in a regeneration zone off gas of a fluid catalytic cracking unit by the select recycle of certain sized ammonia decomposition catalyst particles. The ammonia decomposition may be aided by injection of NO.sub.x into the off gas. The particles are acquired from a separation means through which is passed the regeneration zone off gas. A solid-free regeneration zone off gas and a stream of solid particles, including a noble metal dispersed on an inorganic support, having a size of from 10 to 40 microns, are acquired. The latter segregated particles are then injected into the regeneration zone at a predetermined make-up rate to insure a very short residence time in the dense phase of the regeneration zone and to provide a relatively constant concentration of the NH.sub.3 decomposition catalyst in the dilute phase of the regeneration zone to convert NH.sub.3 to N.sub.2 and water vapor. The regeneration zone is operated in a partial combustion mode defined by a CO content of from 1 to 6 percent by volume.

Process for the reduction of NH.sub.3 in regeneration zone off gas by

A regeneration zone for fluid catalytic cracking contains ammonia (NH.sub.3) when the regeneration zone is operated in a partial combustion mode as defined by a content of CO of between 1 and 6 percent by volume. If the ammonia is not removed from the regeneration zone off gass, the same will be passed to a CO combustion zone where, in the presence of oxygen, CO is oxidized to CO.sub.2 and some of the ammonia will undesirably be oxidized to NO.sub.x. This invention reduces the presence of ammonia in the feed gas to a CO combustion zone of an FCC process by the introduction of a NO.sub.x -containing gas to dilute phase of a regeneration zone or to a regeneration zone off gas. Ammonia, NO.sub.x and oxygen present in the regeneration zone off gas of the regeneration zone, will tend to react to produce nitrogen and water vapor, which then is passed to the CO combustion zone for CO oxidation to CO.sub.2. Where the addition of NO.sub.x is made at temperatures greater than 1700.degree. F., hydroxyl precursor addition may not be required. Where addition is made at temperatures lower than 1700.degree. F. a hydroxyl precursor may be added to the gas admixtures.

Process for the reduction of ammonia in regeneration zone off gas by

A selective catalytic reduction process (SCR) for reducing the oxides of nitrogen (NO.sub.x) content of a furnace flue gas. The process comprises splitting the flue gas into two streams, treating one of the streams with an SCR process with the same amount of NH.sub.3 as NO.sub.x, and then recombining the streams. By treating only a portion of the flue gas using an NH.sub.3 /NO.sub.x ratio of unity, the amount of catalyst required is reduced while the residual NO.sub.x and NH.sub.3 contents of the recombined streams is controlled to desired levels.

Growing community of inventors

Houston, TX, United States of America

Norman C Samish