Claims
- 1. A process for catalytically cracking a hydrocarbon feedstock selected from the group consisting of C.sub.4 to C.sub.7 paraffins, naphthas and light gas oils to selectively produce aromatics, ethylene or a combination thereof comprising:
- (a) introducing the hydrocarbon feedstock to a cracking reactor;
- (b) simultaneously delivering hot acidic cracking catalyst solids to the cracking reactor;
- (c) catalytically and thermally cracking the hydrocarbon feedstock with heat supplied by the hot catalyst solids to form a cracked product;
- (d) separating the cracked product from the hot catalyst solids; and
- (e) quenching the separated cracked product effluent over a bed of solids having catalyst dehydrogenation activity; wherein the total kinetic residence time of the hydrocarbon feedstock from step (a) through step (e) is in the range of from about 0.05 to 2.0 seconds.
- 2. The process of claim 1, wherein the residence time is from about 0.05 to 0.5 seconds.
- 3. The process of claim 1 further comprising:
- (f) delivering the separated catalyst solids to a stripper to remove residual cracked gas products;
- (g) combusting the separated catalyst solids to thereby remove carbon deposits and to heat the stripped catalyst solids to thereby form regenerated catalyst solids; and
- (h) transporting the regenerated catalyst solids to the cracking reactor.
- 4. The process of claim 1, wherein the hydrogenation catalyst is selected from noble metal oxides on an inert carrier.
- 5. The process of claim 1, wherein the temperature of the catalytic cracking reaction is from about 900.degree. to 1500.degree. F., and the weight ratio of catalyst solids to hydrocarbon feedstock is between 1 and 60.
- 6. The process of claim 5, wherein the temperature of the catalytic cracking reaction is from about 1000.degree. F. to 1300.degree. F., and the residence time is 0.1 to 0.3 seconds.
- 7. The process of claim 1, wherein the selectively produced aromatics comprise benzene.
- 8. The process of claim 1, wherein the catalyst solids are selected from the group consisting of silica gel, alumina and clay.
- 9. The process of claim 8, further comprising catalyst support in the catalyst wherein the catalyst support is selected from the group consisting of silica gel, silica-alumina, clays or a mixture of any of the foregoing.
- 10. The process of claim 9, wherein the cracked produce is primarily mono-aromatics and said catalyst solids are thermally deactivated.
- 11. The process of claim 1, comprising delivering the hydrocarbon feed stream and hot catalyst solids to a tubular thermal regenerative cracking reactor through a reactor feeder having vertical passages communicating with the tubular regenerative cracking reactor and the solids in a hot solids vessel, providing localized fluidization of the solids above the vertical passages, and delivering the hydrocarbon feed to the tubular thermal regenerative reactor at an angle to the path of the catalyst solids entering the thermal regenerative reactor.
- 12. The process of claim 1, comprising separating the hot catalyst solids and the cracked product gases in a separator wherein the catalyst solids and cracked product gases enter the separator through a separator inlet and reverse direction ninety degrees and then the product gases reverse direction another ninety degrees to effect a one hundred eighty degree reversal in direction from the entry direction and then the catalyst solids continue in the path oriented ninety degrees from the catalyst solids cracked product gas separator inlet and thereafter, the path of the catalyst solids is directed downwardly and the separated product gases are quenched.
- 13. The process of claim 1, comprising separating the catalyst solids and cracked gases in a separator comprising a chamber for rapidly disengaging about 80% of the catalyst solids from an incoming mixed phase stream, said chamber having approximately rectilinear longitudinal side walls to form a flow path of height H and width W approximately rectangular in cross section, said chamber also having a mixed phase inlet of inside width D.sub.i ; a gas outlet and solids outlet, said inlet being at one end of the chamber and disposed normal to the flow path of height H which is equal to at least D.sub.i, or 4 inches, whichever is greater, and the width W is from 0.75 D.sub.i said solids outlet being at the opposite end of the chamber and being suitably arranged for downflow of discharged solids by gravity, and said gas outlet being between the mixed phase inlet and the solids outlet at a distance no greater than 4 D.sub.i from the inlet as measured between respective centerlines and oriented to effect a 180.degree. change in direction of the gas whereby resultant centrifugal forces direct the catalyst solids in the incoming stream toward a wall of the chamber opposite to the inlet forming thereat and maintaining an essentially static bed of solids, the surface of the bed defining a curvilinear path of an arc of approximately 90.degree. of a circle for the outflow of solids to the solids outlet.
- 14. A process as in claim 1 further comprising the step of injecting alkanes into the reactor upstream of the hydrocarbon feed.
Parent Case Info
CROSS REFERENCE TO RELATED APPLICATIONS
The present application is a continuation of Ser. No. 07/449,130, filed Dec. 8,1989, now abandoned, which in turn is a continuation of Ser. No. 07/149,643, filed Jan. 28, 1988, now abandoned.
US Referenced Citations (18)
Foreign Referenced Citations (1)
Number |
Date |
Country |
2048299 |
Dec 1980 |
GBX |
Non-Patent Literature Citations (1)
Entry |
Chen et al., "Non-regenerative Cat. Cracking of Gas Oils", Indus. and Engineering Develop., vol. 25, No. 3, 1986. |
Continuations (2)
|
Number |
Date |
Country |
Parent |
449130 |
Dec 1989 |
|
Parent |
149643 |
Jan 1988 |
|