Fluid bed combustor and apparatus for cooling particulate solids

Claim 1

A fluidized bed reactor having a housing defining therein a chamber, a bed support plate disposed within the housing and dividing said chamber into a fluidizing zone thereabove and an air plenum therebeneath, means for supplying particulate material including fuel into the fluidizing zone so as to establish a bed of particulate material therein superadjacent the bed support plate, means for supplying air into the air plenum to pass through the bed support plate into the fluidizing zone to fluidize the bed of particulate material, and a bed drain assembly adapted to receive particulate material for removal from the bed, said bed drain assembly comprising: a. first conduit means having a bounding wall defining a passageway having an inlet communicating with the bed for receiving particulate material and an outlet for discharging particulate material therefrom; b. second conduit means disposed coaxially about said first conduit means and defining an annular passageway therebetween having an inlet opening at one end thereof and an outlet opening at the other end thereof for conveying a cooling fluid therethrough in indirect heat exchange relationship with the particulate material passing through said first conduit means; and c. a plurality of heat transfer pins each mounted within the bounding wall of said first conduit means such that a first portion of each of said heat transfer pins extends into the passageway for particulate material defined within said first conduit means and a second portion of each of said heat transfer pins extends into the annular passageway for cooling fluid defined between said first and second conduit means, the first portion of each of said heat transfer pins comprising an axially elongated cylinder-like shell having an open end and a closed end, said shell mounted in said first conduit means with its open end opening to the annular cooling fluid passageway and with its closed end extending into the passageway for particulate material defined within said first conduit means; and the second portion of each of said heat transfer pins comprising an axially elongated rod-like element, said rod-like element having a first end inserted into said cylinder-like shell in closely spaced relationship therewith through the open end thereof to abut the closed end thereof and a second end extending into the annular cooling fluid passageway having a plurality of axially spaced fins extending circumferentially outwardly therefrom within the annular cooling fluid passageway.