Patent ID: 7744745

Claim:
A process for fluid catalytic cracking of hydrocarbon feedstocks with high levels of basic nitrogen, in a multiple riser FCCU, operating with feedstocks A and B, wherein the process comprises the following steps: a) placing in contact with a zeolite catalyst, in a main riser of the FCCU, a hydrocarbon feedstock A which possesses a level of basic nitrogen at least 200 ppm lower than feedstock B that is being processed in a secondary riser of the FCCU; b) simultaneously, placing in contact with the zeolite catalyst, in the secondary riser of the FCCU, a hydrocarbon feedstock B comprised of a mixture made up of between 95 and 40%, in volume, of hydrocarbon streams with a content of catalyst-damaging basic nitrogen of between 1000 and 3500 ppm, and between 5 and 60%, by weight, of a cooling fluid capable of increasing a circulation in the secondary riser and of cooling a regenerator, in order to adjust the thermal balance of the FCCU and maintain a circulation of the catalyst in the main riser, at proper levels, so that a catalyst/oil ratio remains in a range of between 4.5 and 8.5; c) maintaining the operation of the FCCU within the conditions of catalytic cracking; d) recovering from a tube products of the cracking reaction with an increase in conversion of bottom fractions, a greater proportion of gasoline and LPG, at the same time with a lower proportion of coke and combustible gas; e) recovering from a catalyst separation device spent catalyst and passing the spent catalyst to a regenerator for removing coke from the spent catalyst and regenerating the zeolite catalyst; and f) separating the regenerated zeolite catalyst; and g) passing the regenerated zeolite catalyst to the main riser and the secondary riser wherein the regenerated zeolite catalyst is extracted from a single zone within the regenerator.