NOVELTY - Producing ethanol involves flashing carbon dioxide from beer stream (100) to provide degassed beer feed (106); boiling this feed in pre-boiler to provide vapor by-pass fraction (112) and beer column feed stream (114); distilling beer column stream (114) to provide overhead vapor fraction (118) and spent beer fraction (122); distilling vapor by-pass fraction (112) and overhead vapor fraction (118) in rectifier column to provide ethanol-rich rectifier overhead vapor stream (126) and water-rich rectifier bottom stream.    USE - For producing ethanol (claimed), which is of motor fuel grade; useful as alternative to petroleum based gasoline and diesel products.    ADVANTAGE - The process allows free capacity in the rectifier column to be filled by alternative ethanol-water vapor and/or condensate streams from sources other than the existing beer column, allowing improvements in molecular sieve bed regeneration to be used in improving the overall throughput of existing and new plants. The process provides an increase in overall capacity (upto 25.7%) of the ethanol recovery area of a dry grind plant due to extra capacity in the rectifier column and in particular in the upper section of the rectifier column.    DETAILED DESCRIPTION - Producing ethanol involves:    (1) flashing carbon dioxide from a beer stream (100) to provide a carbon dioxide gas stream (104) and a degassed beer feed (106);    (2) boiling the degassed beer feed (106) in a pre-boiler to provide a vapor by-pass fraction (112) and a beer column feed stream (114);    (3) distilling the beer column feed stream (114) in a beer column to provide an overhead vapor fraction (118) and a spent beer fraction (122); and    (4) distilling in a rectifier column, a combination comprising the vapor by-pass fraction (112) and the overhead vapor fraction (118) to provide an ethanol-rich rectifier overhead vapor stream (126) and a water-rich rectifier bottoms stream.    The process further involves dehydrating the rectifier overhead vapor stream (126) by passing the stream through at least one active molecular sieve bed to provide an anhydrous ethanol vapor stream (202).    DESCRIPTION OF DRAWING(S) - The figure shows a system for producing ethanol.    beer stream (100)    carbon dioxide gas stream (104)    degassed beer feed (106)    vapor by-pass fraction (112)    beer column feed stream (114)    overhead vapor fraction (118)    spent beer fraction (122)    ethanol-rich rectifier overhead vapor stream (126)    regenerate ethanol-water stream (130)    anhydrous fuel-grade ethanol vapor stream (202)    water-rich molecular sieve beds. (204)