Patent GB-705134-A (GB)
Title: Moving bed solids circulating system with gas lift for hydrocarbon conversion systems
Inventor: ARDERN DAVID BENJAMIN
IPC: B01J8/00
Filed: 1952-05-08
Abstract: <PICT:0705134/III/1> <PICT:0705134/III/2> <PICT:0705134/III/3> In a hydrocarbon conversion system employing circulating catalytic or other granular contact material which is passed downwardly as a compact mass through one or more treating zones and is subsequently elevated from the bottom of the downflow path by a gaseous lifting medium, the granular material passes downwardly from the lowermost treating zone into a grouped plurality of lift engaging zones, each associated with an upwardly extending lift pipe, the inlets to which pipes are so situated within a bed of granular material as to provide extended paths of communication between the inlets, and gaseous lift medium is introduced into the engaging zones to carry the granular material through the lift pipes to one or more disengaging zones where the solid is separated from the lift gas and returned to the top of the downflow path for repeated circulation.  The process results in reduced attrition of the granular material.  Fig. 2 shows part of an apparatus for catalytic cracking of hydrocarbons; granular catalyst flows from the regeneration zone through pipe 14 into distributing zone 15 and via pipes 17 to lift engaging zones 18; steam of flue gas is introduced at 25, 27, 28 and conveys the catalyst upwardly through pipes 20 to disengaging zones situated above the level of the highest treating zone.  The rate of admission of gas may be controlled in accordance with the pressure existing in the lift pipes.  Four disengaging zones each associated with a group of three lift pipes may be provided Figs. 1, 3, 4, 5 (not shown), or all the lift pipes may lead to a single disengaging zone Figs. 10, 11, (not shown).  The lift pipes are slightly flared at the top so as to reduce the velocity of the catalyst, and the disengaging zones are provided with trays which intercept the falling catalyst in order to reduce attrition. Separated catalyst passes from the disengaging zones to a surge hopper 11 (Fig. 6) and thence to the top of the reaction zone 60. Hydrocarbons enter at 69 and are sprayed through head 70 against an annular curtain of falling catalyst.  The major part of the catalyst passes through conduits 68, and additional hydrocarbon is introduced at 74.  Reaction product collects in inverted channels 78, 78a, and in space 60a, and is removed at 80; the catalyst flows through pipes 81, is purged by steam entering at 83, and then passes through pipes 84 to the two-stage regeneration section 61, 62 (Fig. 7) where it is treated with air.  In the second regeneration stage the catalyst is supported by plate 90, and the air entering at 88 passes through apertures 98 and pipes 99 carrying caps 100; the catalyst flows through conduits 92, 93 into withdrawal device 94 provided with funnels 105.  A portion of the catalyst is withdrawn through line 200 (Fig. 6) and passes to an elutriator Fig. 9 (not shown) where fines are removed by countercurrent treatment with a gas; make-up catalyst may be supplied to the elutriator.