Abstract: A feed-dispersion system for hydrocarbon feeds of fluid catalytic cracking units is described, which comprises: a feed-injection system made up of two concentric conduits, where the atomization fluid flows through the inner conduit, while the liquid feed flows through the annular space formed by the outer surface of the inner conduit and the inner surface of the outer conduit; an atomization unit having nozzles arranged in rows, with one row having central nozzles connected to the inner conduit for atomization fluid, and two or more rows of side nozzles, connected to the outer feed conduit, the central nozzles and side nozzles of the atomization unit being geometrically placed so that the energy of the atomization fluid is fully transferred by contact to the flow of feed, this resulting in the complete atomization of the feed; a mixing chamber formed by the edges of the central nozzles, the dimensions of which are able to prevent the coalescence of the formed oil droplets.

Abstract: A process for the fluid catalytic cracking of heavy feeds under a heat balance regime is described, where one or more catalyst coolers external to the regenerator cool a stream of regenerated catalyst. A portion of said stream returns to the regenerator and a portion of the cooled regenerated catalyst is admixed to the non-cooled regenerated catalyst at a temperature substantially lower than the regenerator temperature, said admixture being brought into contact with the hydrocarbon feed to be cracked. As a result, the control of the catalyst circulation is rendered independent from the heat balance of the unit, with minimization of the thermal cracking, and therefore lower coke and fuel gas products.