Drying wet granular solid materials

Claim 1

A PROCESS FOR DRYING A STARTING WET FINELY DIVIDED GRANULAR SOLID MATERIAL WHICH IS WETTED SUBSTANTIALLY ON THE SURFACE WITH A VOLATILE LIQUID TO OBTAIN PRACTICALLY DRY GRANULAR SOLID MATERIAL AND TO RECOVER THE VOLATILE LIQUID BY CONVEYING THE STARTING WET GRANULAR SOLID MATERIAL BY MEANS OF UNHEATED CARRIER GAS INTO THE BOTTOM OF A VERTICALLY DISPOSED HEATING ZONE, THE CARRIER GAS BEING A MIXTURE OF A MATERIAL WHICH IS A GAS AT STANDARD CONDITIONS AND INERT WITH RESPECT TO THE WET GRANULAR MATERIAL AND VAPORS OF THE SAME VOLATILE LIQUID AS THAT WETTING THE SURFACE OF THE STARTING WET GRANULAR SOLID MATERIAL, SUCH VAPORS SUBSTANTIALLY SATURATING THE CARRIER GAS SUCH THAT THE DEW POINT OF THE MIXTURE IS NOT APPRECIABLY HIGHER THAN THE ACTUAL TEMPERATURE OF THE STARTING WET GRANULAR SOLID MATERIAL, MAINTAINING THE GRANULAR MATERIAL AS A FLUIDIZED BED IN THE HEATING ZONE, HEATING THE FLUIDIZED BED BY INDIRECT HEAT EXCHANGE MEANS AND CONTACT WITH HEAT TRANSFER SURFACES IN THE HEATING ZONE TO VARPORIZE THE VOLATILE LIQUID, PASSING THE RESULTING SOLID-GAS MIXTURE CO-CURRENTLY UPWARD THROUGH THE HEATING ZONE AND TO A SEPARATING ZONE, SEPARATING THE SOLID GRANULAR MATERIAL FROM THE VAPOROUS MATERIAL AND COLLECTING THE RESULTING PRACTICALLY DRY GRANULAR SOLID MATERIAL, PASSING THE VAPOROUS MATERIAL TO A CONDENSING ZONE AND CONDENSING A PART OF THE VOLATILE LIQUID VAPORS, COLLECTING THE RESULTING LIQUID CONDENSATE AND PROVIDING A NON-CONDENSED VAPOR MIXTURE OF THE MATERIAL WHICH IS A GAS AT STANDARD CONDITIONS AND VAPORS OF THE VOLATILE LIQUID SUCH THAT THE VAPORS OF THE LIQUID SUBSTANTIALLY SATURATE THE NON-CONDENSED VAPOR MIXTURE AND THAT THE DEW POINT OF THE MIXTURE IS NOT APPRECIABLY HIGHER THAN THE ACTUAL TEMPERATURE OF THE STARTING WET GRANULAR SOLID MATERIAL, AND PASSING THE NON-CONDENSED VAPOR MIXTURE BACK TO THE HEATING ZONE AS THE AFOREMENTIONED CARRIER GAS FOR CONVEYING THE WET GRANULAR SOLID STARTING MATERIAL.