Abstract: The invention relates to a method of drying a solid material containing less than 95% by weight of a vaporizable material which comprises establishing a fluidized bed containing the solid material, introducing fluidizing medium, heating the fluidized bed indirectly, feeding the solid material to be dried to the fluidized bed and removing dried solid material therefrom, and removing vapor product from the fluidized bed. In accordance with the present invention the fluidizing medium is the vaporizable material in vapor form and vapor product comprising the vaporizable material substantially uncontaminated by other gases is removed from the fluidized bed for further use. By producing a vapor product substantially uncontaminated by other gases, the invention enables economic recovery of the vaporizable material per se, as well as the latent heat thereof, which is of particular value when the vapor product is steam.

Abstract: The invention resides in an electrical power generation system comprising means for burning solid carbonaceous fuel, such as brown coal, to generate heat energy which is used to convert water to steam, turbine means driven by the said steam for producing electrical energy, and solid carbonaceous fuel drying means, wherein moist fuel is indirectly heated by steam in the drying means in the absence of introduced air or other gases, whereby water vapor substantially free from air or other gases is driven off from the fuel for further use and the dried fuel is passed to the burning means. Preferably, the solid carbonaceous fuel drying means is in the form of a fluidized bed in which the fluidizing medium is water vapor. Further, the fluidized bed may be indirectly heated by saturated steam which transfers heat to the solid carbonaceous fuel and becomes condensed.

Abstract: The invention resides in one embodiment in a multiple effect method of and apparatus for drying a solid material containing a vaporizable material which comprises establishing at least first and second fluidized beds containing the solid material in which in at least the first fluidized bed the fluidizing medium is the vaporizable material in vapor form and in which the fluidized beds are heated indirectly, such that vaporizable material is removed from the solid material, the vaporizable material removed from the solid material in the first fluidized bed being used to provide the indirect heating of the second fluidized bed.

Abstract: In a process for the production of alumina which comprises the steps of digesting bauxite to produce a precipitate of alumina trihydrate containing uncombined moisture, drying the alumina trihydrate to reduce the uncombined moisture content thereof, and feeding the dried alumina trihydrate to a calciner to convert the alumina trihydrate to alumina, improved economy is achieved by drying the alumina trihydrate in a fluidized bed in which the fluidized mass is heated indirectly by means of steam which is available from the digestion and recovery system. Drying of the alumina trihydrate in this manner prior to feeding it to the calciner also reduces the fuel requirement in the calciner and enables the throughput of the calciner to be increased.