Claims
- 1. A fluidized catalytic cracking process for catalytically cracking a feed, which is a heavy hydrocarbon feed comprised of hydrocarbons having a boiling point above 350° C. and including heavy residues containing from 2 to 10 wt % of conradson carbon residue, to lighter products in a fluidized catalytic cracking apparatus utilizing a heated catalyst which is a fluidizable cracking catalyst, the process comprising the steps of:a. introducing the heated catalyst and the feed into a bottom riser of the fluidized catalytic cracking apparatus and allowing the heated catalyst and the feed to preaccelerate upwardly within the bottom riser as a mixture of the heated catalyst and hydrocarbon vapors; b. flowing the mixture upwardly from the bottom riser through a plurality of microriser tubes disposed within a regenerator under conditions effective to cause a cracking reaction of the hydrocarbons and result in a mixture including coked catalyst and hydrocarbon vapors; c. passing the mixture including coked catalyst and hydrocarbon vapors from the microriser tubes through a catalyst separator for separating the coked catalyst from the hydrocarbon vapors; d. collecting coked catalyst in a stripper for stripping out hydrocarbon vapors carried along with the coked catalyst and introducing the coked catalyst collected into a regenerator; e. simultaneous with step (b), combusting the coked catalyst within the regenerator under conditions effective to cause regeneration of the catalyst so that hot regenerated catalyst is produced and heat transferred to the microriser tubes; f. introducing the hot regenerated catalyst from the regenerator into the bottom riser according to step (a) for facilitating continuous operation; and g. directing hydrocarbon vapors from the catalyst separator and from the stripper to a fractionator for separation of products.
- 2. The process as claimed in claim 1, further comprising injecting steam into the bottom riser in step (a) to cause a flow of the feed and the heated catalyst in the bottom riser having a velocity ranging from 4 to 6 m/s.
- 3. The process as claimed in claim 1, wherein the mixture in the microriser tubes in step (b) flows at a velocity ranging from 2 to 3 m/sec.
- 4. The process as claimed in claim 1, wherein the mixture is present in the microriser tubes in step (b) for a residence period ranging from 2 to sec.
- 5. The process as claimed in claim 1, wherein the coked catalyst is regenerated in step (e) in the presence of air so that exothermic heat is produced and transferred to the microriser tubes resulting in further heating of the mixture of the heated catalyst and hydrocarbons vapors, and producing a cooling effect in the regenerator so as to maintain the regenerator at a temperature ranging from 650 to 700° C. and thereby eliminate the need for external cooling of the hot regenerated catalyst.
- 6. The process as claimed in claim 1, wherein coked catalyst from the separator is stripped of hydrocarbon vapors in step (d) in the presence of a counter current flow of steam having a flow rate ranging from 1 to 5 kg/100 kg of catalyst.
- 7. The process as claimed in claim 1, further comprising passing flue gases containing hot regenerated catalyst entrained therein through at least one cyclone for separating the hot regenerated catalyst from the flue gases, and recycling the hot regenerated catalyst into the regenerator.
CROSS-REFERENCE TO RELATED APPLICATION
This is a division of application Ser. No. 08/843,287 filed Apr. 11, 1997, now U.S. Pat. No. 6,027,696 issued Feb. 22, 2000.
US Referenced Citations (4)
Foreign Referenced Citations (2)
Number |
Date |
Country |
2100747 |
Jan 1983 |
GB |
9424508 |
Oct 1994 |
WO |