Abstract: A catalytic reaction chamber for contacting a reactant stream with catalyst particles which are disposed as an annular-form bed and are downwardly movable therethrough via gravity-flow. The annular catalyst bed is spaced between a catalyst-retaining screen and a scalloped, perforated centerpipe. A plurality of vertically-positioned catalyst-transfer, or withdrawal, conduits are circumferentially-disposed substantially adjacent the outer surface of the scalloped centerpipe and extend the entire length of the catalyst bed. These contain a first plurality of apertures which face into the bed of catalyst particles and which are sized to permit catalyst particles to flow therethrough. A second plurality of apertures is disposed opposite the first plurality of apertures, and sized to inhibit the flow of catalyst particles therethrough.

Abstract: A catalytic reaction chamber for contacting a reactant stream with catalyst particles which are disposed as an annular-form bed and are downwardly movable therethrough via gravity-flow. The annular bed is spaced between a catalyst-retaining screen and a perforated centerpipe. A plurality of vertically-positioned catalyst-transfer, or withdrawal, conduits are circumferentially-disposed substantially adjacent the outer surface of the centerpipe and extend the entire length of the catalyst bed. These contain a first plurality of apertures which face into the bed of catalyst particles and which are sized to permit catalyst particles to flow therethrough. A second plurality of apertures is disposed substantially 180.degree. opposite the first plurality of apertures, and sized to inhibit the flow of catalyst particles therethrough.

Abstract: An improved radial flow moving bed reactor, or other type of fluid-solid contacting vessel, in which stagnant catalyst volumes are reduced. The improvement results from the placement of a plurality of catalyst collection scoops or a single discoid cover plate just above the catalyst withdrawal conduits in a manner which directs the removal of catalyst through an annular opening adjacent the inner catalyst retention screen.