Control of contact time in transport reactors

Claim 2

The process of claim 1 wherein the petroleum stock is a petroleum gas oil.

Claim 3

The process of claim 1 wherein the conversion catalyst comprises a fluidizable solid selected from the class consisting of silica-alumina, silica-magnesia, and silica-zirconia.

Claim 4

The process of claim 4 wherein the catalyst additionally comprises a crystalline aluminosilicate.

Claim 5

The process of claim 5 wherein a petroleum gas oil is catalytically cracked at a temperature in the range from 850* to 1,050* F., a catalyst-oil weight ratio in the range from 2.0 to 20.0, and an upward fluid dispersion velocity in the range from about 10 feet per second with an open internal tube to about 60 feet per second with a closed internal tube.

Claim 6

In a cyclic fluid-dispersion catalytic cracking system, comprising in combination an elongated, vertical transport reactor, a spent-catalyst stripper, a catalyst regenerator and product recovery means, apparatus for catalytic cracking comprising: a. an elongated, vertical, cylindrical reactor vessel, having a bottom and a curved top; b. an entry tube, having a smaller diameter than the reactor vessel, coaxial therewith and extending downwardly from the bottom of the vessel, to receive oil feed and regenerated catalyst together with dispersion and fluidizing steam; c. an exit tube, located near the top of the reactor vessel and extending horizontally therefrom, whereby the catalyst-oil dispersion is removed from the reactor vessel; d. an elongated, vertical, cylindrical riser tube, contained within the cylindrical reactor vessel, having open bottom and top ends; e. riser tube support means, anchored to the inner wall of the reactor vessel and maintaining the riser tube coaxial with the reactor vessel at a distance below the top of the reactor vessel such that the top end of the riser tube is located below the exit tube; f. closure means, attached to the top end of the riser tube; g. a cylindrical guide sleeve, coaxial with the reactor vessel and the riser tube, attached to the top of the vessel and extending therethrough; h. rod means, attached to the closure means and extending upwardly through the guide sleeve; and i. control means, attached externally of the reactor to the rod means and adapted to movably adjust the vertical positioning of the rod means and the closure means, thereby varying the degree of closure of the top end of the riser tube within the range from a fully open to a fully closed position and effecting control of the upward velocity of the fluidized catalyst-oil dispersion.

Claim 7

The apparatus of claim 7 wherein the closure means comprises a plug valve.

Claim 8

The apparatus of claim 7 wherein stabilizing guide means are affixed to the riser tube and to the internal wall of the reactor vessel at intervals along their respective vertical lengths.

Claim 9

The apparatus of claim 7 wherein the ratio of inside diameters of the reactor vessel to the riser tube is in the range from 1.5 to 4.