Abstract: Hot gases for fluidizing the preheat compartment of a multi-bed fluid bed reactor are cooled by injection of water, or cool air and water, to reduce scaling of the ducts, hot cyclone, hot windbox and the tuyeres in the constriction dome separating the hot windbox from the preheat compartment.

Abstract: Apparatus for removing grit and fiber from waste activated sewage sludge prior to introduction into a centrifuge for further separation. Grit removal is accomplished by hydrocyclones and fiber removal is carried out on a 300.degree. screen. The hydrocyclones and screen, together with connecting conduits, are conveniently mounted on a supporting frame for facilitating transportation of the unit and for maintaining the predetermined structural relationships of the various members.

Abstract: A fluidized bed reactor is provided with vertically oriented heat exchange coils for controlling the temperature of the fluidized bed. Tuyere elements discharge fluidizing gas at a level substantially above the constriction plate. The bed solids below the level of the tuyere ports constitute a static layer during fluidization and the lower return bends of the heat exchange coils are embedded in this layer and so are shielded from erosion by the fluidized solids of the bed proper.

Abstract: A fluidized bed reactor is provided with heat exchange coils for controllng the temperature of the fluidized bed. The heat exchange coils are vertically oriented and elements thereof pass through the constriction plate of the reactor. Multiple function Tuyere elements are provided which admit air into the reaction chamber from the windbox, provide for passage of elements of the heat exchange coils through the constriction plate, structurally support the heat exchange coils in position and constitute thermal sleeves for accommodating differential thermal expansion of the heat exchange coils and the constriction plate.

Abstract: A centrifugal separator having a bowl and means to rotate the bowl about a longitudinal axis, the bowl including a cylindrical section and a coextensive conical section whereby, in use, a bath of feed material will form partially up the conical section as the bowl rotates with the remainder of the conical section forming a beach area up which separated solids are conveyed by a screw conveyor adapted to collect separated solids from adjacent the inside wall of the bowl and convey them out of the bath and up the beach to an outlet from the bowl, with weir means in the form of an overflow passage to allow substantially solid free liquid to be removed from the bowl, a first conduit extending into the bowl through one end thereof and coincident with the rotation axis thereof, and one, or more second conduits within and coaxial with respect to the first conduit and each other to define an inner passage and at least one outer annular passage through which feed material, and at least one separate treatment material m

Abstract: An electro-ultrafiltration process is conducted in a tank in which the cathode and anode regions are separated by an anisotropic ultrafiltration membrane. A pressure differential is applied across the membrane and the fluid component of the bath moves through the membrane under the influence of this pressure for removal from the tank. Current applied between the electrodes develops an additional flow of the fluid component of the bath through the membrane. Due to the special characteristics of the anisotropic membrane, the total flux through the membrane under these conditions greatly exceeds the flux attributable to the individual effects of pressure and current. This process is especially useful when applied in electrophoretic coating systems, for it can establish a stable bath composition and it also tends to maintain the membrane in an essentially unfouled condition.

Abstract: Sewage sludge of a uniformly high solids content is pumped from a primary settling tank to a digester or thickener by an air operated spring assisted diaphragm pump.