Abstract: A fluidized bed incinerator is provided with feed pipes which are downwardly directed or vertically oriented and have access to the reaction chamber. Secondary air is introduced into the reaction chamber at a point above the fluidized bed through pipes which are concentric with the feed pipes and spaced therefrom in surrounding relation to define annular air passageways. Air passing into the reaction chamber through these passageways provides an air shield about the feed pipes.

Abstract: A fluidized bed waste incinerator is operated with a space rate such that essentially the entire reactor chamber is occupied by a dilute fluidized bed. Particulate solids elutriated with the exhaust gases are returned to the reactor chamber to thereby conserve the heat generated in the reactor chamber.

Abstract: Heat exchanger tubes exposed to high-temperature gases from which dust or scale is deposited on the tubes are subjected to forces applied at the resonant frequency of the tube array to remove deposits on the tube surfaces.

Abstract: Phosphate rock is calcined under conditions calculated to completely oxidize the carbon and sulfur in the rock. Calcination is also conducted at elevated temperature to eliminate cadmium metal, a poisonous substance in fertilizers, from the calcined rock product. A fluid bed system for eliminating cadmium metal in the calcination of phosphate rock involves a two-vessel system in which an independent cadmium removal vessel served by a separate fluidizing air stream carries out volatilization of cadmium, while preheating, precalcining and cooling is conducted in another multi-bed reactor which is served by a separate fluidizing air stream.

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: 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.