Abstract: A process is described for producing a fermentation product such as ethanol, in which a feedstock is formed consisting of a slurry of starch and acid combined with a recycle stream of non-fermented carbohydrate material from a fermenter. This combined feedstock at a solids content of 15 to 30% is hydrolyzed in a single continuous hydrolyzer of a high intensity type to form a hydrolyzate in fluid form containing at least 80% glucose. The hydrolyzate is fermented to form a fermentation product and the fermentation product is distilled, leaving a distillation residue containing non-fermented carbohydrate material. This distillation residue forms the recycle stream and a substantial proportion of the non-fermented material is hydrolyzed together with the starch in a single hydrolysis stage to a fermentable glucose-containing fluid.

Abstract: A feedstock slurry of starch and acid is continuously moved through a high intensity tubular starch hydrolyzer to produce a fluid hydrolyzate containing glucose. This glucose-containing fluid is then fermented to form a fermentation product containing ethanol which is then distilled to separate the ethanol from the residue of the distillation which contains non-fermented carbohydrate materials. At least part of the distillation residue is recycled as part of the feedstock slurry of starch and acid to the hydrolyzer, thus allowing a substantial portion of the previously unfermented feedstock to be hydrolyzed to a fermentable glucose-containing fluid.

Abstract: A process and apparatus are described for producing a modified carbohydrate material, preferably starch, in fluid form. In the process a starch slurry is continuously moved through a confined tubular preheat zone where heat is very rapidly transferred to the slurry, whereby the slurry passes through a gelation stage and forms into a hot free flowing liquid. The heat transfer is from superatmospheric steam surrounding at least part of the tubular heating zone, the temperature of the steam and the cross-sectional area of each tubular preheat zone being selected to rapidly transfer heat from the steam throughout the slurry and minimize the magnitude of the zone of high viscosity gel formed during the gelation stage. The hot liquid formed is immediately forced through a restrictive opening and into a confined tubular reaction zone accompanied by a sudden decrease in pressure whereby the starch is made highly reactive.