| abstract |
Lower alkanes are converted to olefins in a 'third bed' external catalyst cooler (ECC) in which hot catalyst, from a first regenerator ('second best') operating in conjunction with a fluid catalytic cracker ('first bed'), thermally cracks and dehydrogenates the alkanes. Because this is an endothermic reaction, the catalyst is autogeneously cooled before it is recirculated to the FCC regenerator. The cracking catalyst is the catalyst of choice in the FCC reactor. Maximum conversion of alkanes to olefins is sought, and can be maintained because the FCC regenerator burns the coke made during alkane dehydrogenation. The olefins produced are then oligomerized in an oligomerization reactor ("fourth" bed) operating in conjunction with a second regenerator ("fifth" bed) to produce a gasoline range stream. The interrelataed operation of this combination of five fluid beds is tailored to convert all available low value alkanes, to olefins which are generally in high demand for several uses, particularly to make high value gasoline. |