CONTINUOUS FERMENTATION AND STRIPPING OF ETHANOL

Recycling the contents of a continuous fermenter through a stripping c olumn is proposed as a means of reducing product inhibition and loweri ng the cost of fuel ethanol production. A 2-L fermenter and 10-cm pack ed column were continuously operated for 150 days without contaminatio n. Some fouling of the packing with attached yeast cells was observed which partially blocked the column. Cell yield was lower than in a sim ple continuous fermenter. Complete conversion of 200 g/L glucose feed and 90% conversion of 600 g/L glucose feed were achieved. Data were an alyzed by computerized process simulation. Cost analysis indicated tha t, with heat recovery to reduce heating and cooling costs, the continu ous fermentor/stripper is possibly a lower-cost alternative to convent ional fermentation and distillation.