Process and apparatus for catalytic cracking of residual oils

Claim 1

A process for the catalytic cracking of a heavy, metals laden hydrocarbonaceous feed by contacting a hot regenerated catalyst stream with the feed in a base of riser reactor, cracking the feed in the riser reactor at catalytic cracking conditions to form cracked products and coked catalyst containing metals, separating the coked catalyst from cracked products, stripping the coked catalyst with steam and regenerating the steam stripped catalyst regenerator with an oxygen-containing gas to form hot regenerated catalyst, characterized by: (a) using a mixture of fluidizable catalytic cracking catalyst and a demetallizing additive, which mixture is resolvable by elutriation; (b) demetallizing the feed by contacting the feed in the base of the riser reactor with the demetallizing additive and removing a majority of the metals and some coke from the feed to produce a coked additive containing a majority of the metals content of the feed and a demetallized feed; (c) cracking the demetallized feed in the riser reactor with the hot regenerated cracking catalyst and discharging from the riser reactor cracked products and a mixture of coked cracking catalyst and coked additive; (d) regenerating the mixture in a first stage regenerator having a base, at least one inlet for coked catalyst and additive, an upper outlet and a lower outlet by adding the mixture to the first stage regenerator, contacting the mixture with an oxygen-containing gas at coke combustion conditions, segregating by elutriation a dense phase fluidized bed with an increased concentration of demetallizing additive, relative to the mixture discharged from the riser, to form a dense phase fluidized bed of regenerated demetallizing additive with a reduced coke content and partially regenerated catalytic cracking catalyst; (e) removing from the lower outlet of the first stage regenerator a regenerated demetallizing additive and recycling it to the base of the riser reactor; (f) removing from the upper outlet of the first stage regenerator the partially regenerated catalytic cracking catalyst and discharging it into a second stage regenerator; (g) regenerating the partially regenerated catalytic cracking catalyst with an oxygen containing gas in the second stage regenerator to produce regenerated catalytic cracking catalyst; (h) recycling regenerated catalytic cracking catalyst from the second stage regenerator to the riser reactor.