Heat recovery in distillation process

A process for the separation and recovery of ethanol from an aqueous fermentate comprising a liquid mixture consisting essentially of ethanol in water and a minor portion of suspended solid matter, the process comprising;

• separating and discharging said solid matter from said mixture in an evaporator, producing evaporator vapors during separation of said solid matter, recompressing said evaporator vapors by means of a compressor and condensing the compressed vapors, fractionating said liquid mixture under reduced pressure fractionation into vapors rich in ethanol and liquid bottom product rich in water, recompressing said vapors rich in ethanol in a compressor and condensing the vapors to form a liquid product rich in ethanol, withdrawing said liquid product containing at least about 97 volume percent ethanol, driving each of said compressors by an engine, said engine producing recoverable waste heat, and using at least a portion of said recoverable waste heat for heating said fermentate or said discharged solid matter.

A process for separation and recovery of ethanol from a fermentate comprising a liquid mixture consisting essentially of ethanol in water and a minor portion of suspended solid matter, the process comprising:

• passing said liquid mixture to a fractionation stage and fractionating said mixture under reduced pressure fractionation into vapors rich in ethanol and a liquid bottom product rich in water, withdrawing the vapors and withdrawing the bottom product, recompressing said vapors rich in ethanol in a compressor, condensing the vapors to form a liquid product rich in ethanol, withdrawing said liquid product containing at least about 97 volume percent ethanol, driving said compressor by an engine, said engine producing recoverable waste heat, and using at least a portion of said recoverable waste heat for heating said fermentate or said bottom product.