Method and apparatus for feeding granular contact material into a dilute phase pneumatic lift

摘要

PICT:0780526/III/1 PICT:0780526/III/2 Apparatus for introducing a granular contact material, e.g. catalyst, into the lower end of a lift pipe 31, Fig. 2, comprises an annular passageway 39 at an angle of 65-85 degrees with the horizontal, lift gas inlets 46 at the base of the passageway, and inlets 38 for introducing the granular material into the passageway. Catalyst is fed into lift tank 29, where it forms a compact bed, and flows through orifices 35 controlled by members 36 to the inlets 38. The width of the annular passageway 39 may increase in an upward direction, and may be 1/2 to 4 inches at the point of catalyst entry; the cross-sectional area of the passageway may remain substantially constant from top to bottom and substantially equal to the cross-sectional area of the lower end of the lift pipe. In a modification, Fig. 3 (not shown), the catalyst flow is controlled by slide valves at the bottom of the lift tank and the lift gas is fed into a horizontal chamber beneath the annular passageway and directed upwardly by means of vertical vanes in the passageway. In another modification, Fig. 7, two annular passageways 74, 75 are provided to which catalyst is fed through conduits 83, 82 respectively from annular vessel 72. Lift gas is supplied through pipes 79, 80, 81. Restricting orifice plates 84, 85 are provided in conduits 82, 83 to convert compact transfer of the solids to free-fall flow. The apparatus is suitable for use in hydrocarbon conversion processes (e.g. cracking) in which granular contact material or catalyst is gravitated as a compact mass through reaction and regeneration zones and is then pneumatically lifted from beneath the regeneration zone to above the reaction zone. By using the apparatus described, the attrition rate of the solid material is reduced.