(under subclass 146) Processes wherein during the contacting process solids are added to the system to make up losses or selected fractions of the solids are withdrawn from the system.
(1) Note. This subclass contains, for example, those solids contacting processes wherein (a) catalyst is added to the circulating mass to maintain constant catalyst inventory and thus replenish normal losses to maintain a constant average catalytic activity, or; (b) solids below the desired catalytic activity are discarded from the system or solids that are too fine or have grown in size are discarded thereby preventing any interruption of normal solids flow in the system.
