The Boc Group, Inc.

Other

Mobil Oil Corporation

Raghu K Menon

Ramakrishnan Ramachandran

Scott A Stevenson

Amos A Avidan

Mark F Mathias

Martin Bulow

Gerald J Teitman

Virginia A Malik

Joseph F Sodomin, Iii

Coke is burned in the regenerator vessel of an FCC complex with a combustion medium consisting of a diluent gas, such as air, enriched with oxygen, The regenerator is operated in partial combustion mode and excess oxygen is introduced into the combustion zone of the regenerator. Emission of nitrogen oxides to the atmosphere is reduced.

Reduction of emissions from FCC regenerators

Hydrocarbon fluid catalytic cracking (FCC) plants are debottlenecked by subjecting part or all of the wet gas stream leaving the main fractionator overhead receiver to pressure swing adsorption to remove methane and hydrogen from this gas stream prior to its introduction into the wet gas compressor. This allows debottlenecking of the compressor system. It can allow the reduction in pressure in the system back to the catalyst regenerator. The reduction in pressure in the catalyst regenerator makes it possible to increase the rate of regeneration of catalyst. Consequently, the rate of hydrocarbon throughput in the FCC plant can be increased.

Hydrocarbon catalytic cracking process

A hydrocarbon stream is cracked to produce a hot gaseous stream which is compressed and cooled to condense almost all of the hydrocarbons contained in the stream. A noncondensed stream remaining after the condensation step, comprised predominantly of hydrogen and C.sub.1 to C.sub.3 hydrocarbons, is subjected to pressure swing adsorption or temperature swing adsorption at an adsorption temperature of about 0.degree. to about 250.degree. C. in a bed of adsorbent which selectively adsorbs ethene and propene, thereby adsorbing substantially all of the ethene and propene from the gas stream. The ethene and/or propene is recovered upon bed regeneration. Higher alkenes are separated from alkanes by various methods.

Hydrocarbon alkylation process

Coke deposits are removed from particulates by combustion in a regenerator by a process in which air is initially used as the oxidant. The combustion gas is subjected to a separation process to remove nitrogen therefrom, and the remaining carbon dioxide-enriched gas stream is recycled to the regenerator together while substantially pure oxygen is introduced into the regenerator. As the level of carbon dioxide in the system increases, the amount of air being introduced into the regenerator is gradually reduced and, in compensation, the amount of oxygen flowing to the regenerator is gradually increased. Eventually, part or all of the air is replaced by oxygen and carbon dioxide recycle gas, and the level of oxygen and carbon dioxide are regulated to maintain the desired temperature in the regenerator.

Process for decoking catalysts

Hydrocarbon fluid catalytic cracking (FCC) plants are debottlenecked by replacing air feed to the cracking catalyst regenerator with oxygen and carbon dioxide exhaust from the catalyst regenerator and removing methane and hydrogen from the wet gas stream leaving the main fractionator overhead receiver prior to its introduction into a wet gas compressor system. Nitrogen is removed from the exhaust gas and methane and hydrogen are removed from the wet gas in the same pressure swing adsorption (PSA) plant. During air replacement, exhaust gas is processed in the PSA plant and when the desired amount of nitrogen is removed from the exhaust gas, feed of exhaust gas to the PSA plant is terminated and flow of wet gas to the PSA plant is initiated.

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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Medford, NJ, United States of America

Raghu K Menon