Patent ID: 6059958
Filing Date: 2000-05-09
Classification: C10G

Abstract:
A process for the fluid catalytic cracking of heavy feeds under conditions of fluid catalytic cracking and in the absence of any added hydrogen, which comprises the following steps:a) contacting a heavy hydrocarbon-containing feed and a catalyst stream in a conversion zone or riser, where the catalyst stream is a mixture of two regenerated catalyst streams, such streams being at different temperatures and such mixture comprising a main catalyst stream of hot regenerated catalyst and a secondary catalyst stream of cooled regenerated catalyst, the catalyst mixture having attained an equilibrium temperature, said contacting being such as to yield vapor phase hydrocarbons from the catalytic cracking of such feed as well as coke in a solid phase which is deposited on the catalyst, so as to reduce its activity;b) from said mixture of catalyst streams, separating a stream of cracked hydrocarbons by means of adequate devices placed beyond the conversion zone or riser;c) conveying said separated catalyst stream to a stripping zone, then to a regeneration zone and effecting the combustion of the coke deposited on the catalyst particles so as to obtain particles of regenerated catalyst of higher activity based on the spent catalyst, at a temperature which is relatively higher than the temperature of the said catalyst mixture;d) conveying a portion of the hot regenerated catalyst stream from step c) to a catalyst cooler which is external to the regenerator and the stripping zone so as to obtain a stream of cooled regenerated catalyst stream;e) conveying a portion of the cooled regenerated catalyst from step d) to the mixing zone which precedes the conversion zone or riser while returning another portion of the cooled regenerated catalyst stream to the regenerator;f) conveying a portion of the hot regenerated catalyst stream from step c) to the mixing zone which precedes the conversion zone or riser, so as to form a catalyst mixture at an equilibrium temperature;(g) combining the stream of hot regenerated catalyst of step (c) and cooled regenerated catalyst of step (d) in the mixing zone which precedes the reaction zone, thus forming a catalyst mixture at an equilibrium temperature; andh) combining the hot regenerated catalyst stream of step c) and the cooled regenerated catalyst stream of step d) and the heavy feed to be cracked in the conversion zone or riser, under a heat balance regime.