Fluid bed reactors

Claim 2

Apparatus according to claim 1 wherein said last-mentioned means comprises a flapper valve mounted so as to open under the influence of catalyst flowing downward in said downcomer pipe.

Claim 3

Apparatus according to claim 1 wherein said last-mentioned means comprises a cup disposed over but in spaced relation to said bottom end of said pipe.

Claim 4

Apparatus according to claim 1 wherein the bottom end of said downcomer terminates below the level at which said at least one reactant vapor is introduced to said catalyst bed.

Claim 5

Apparatus according to claim 1 wherein said vessel has a diameter of at least 3 feet and said downcomer pipe has a diameter of at least 2 inches.

Claim 6

Apparatus according to claim 1 wherein said catalyst bed comprises a second reaction zone located above said first-mentioned reaction zone, and further including means for introducing a reactant to the bottom end of said second reaction zone.

Claim 7

Apparatus according to claim 7 including a downcomer pipe with open top and bottom ends disposed wholly within said second reaction zone, and means at the bottom end of said second downcomer pipe for limiting upward flow of gas and vapor through said second pipe while permitting catalyst in said second pipe to be discharged through the bottom end thereof.

Claim 8

In a system for catalytically reacting at least two reactants in the vapor phase and concurrently regenerating spent catalyst by contact with a gaseous regenerating agent, said system comprising a reactor vessel, a fluidized dense phase catalyst bed of a selected particulate catalyst in said vessel, said bed comprising a catalyst regeneration zone to which said gaseous regenerating agent is admitted and at least one reaction zone located above said catalyst regenerating zone to which said reactants are delivered, and said vessel also having a catalyst disengaging zone above said bed from which reaction effluent is recovered, the improvement which comprises at least one downcomer pipe located within said bed for circulating catalyst from said at least one reaction zone to said catalyst regenerating zone, said pipe extending from said at least one reaction zone to said catalyst regenerating zone and having an open top end that terminates short of the upper end of said bed and an open bottom end that terminates short of the lower end of said bed, and means in said bed at the bottom end of said pipe for limiting upward flow of gases through said pipe while permitting discharge of catalyst particles flowing downward in said pipe.