Energy-Efficient Membrane Separations in the Sweetener Industry. Final Report

摘要

Objective was to investigate the use of membrane processes as energy-efficient alternatives to certain conventional separation processes now in use in the corn-sweetener industry. Three applications of membranes were studied during the program: the concentration of corn steep water by reverse osmosis; the concentration of dilute wastes, called ''sweetwater,'' by a combination of reverse osmosis and countercurrent reverse osmosis; and the enrichment of corn syrup in fructose by a process involving selective complexation of fructose by membrane filtration. Laboratory experiments were conducted for all three applications, and the results were used to conduct technical and economic analyses of the process. Calculations indicate that the use of reverse osmosis in combination with conventional mechanical-vapor-recompression evaporation to concentrate steep water, offers savings of a factor of 2.5 in capital costs and a factor of 4.5 in operating costs over currently used evaporation alone. In the concentration of sweetwater by reverse osmosis and countercurrent reverse osmosis, capital costs would be about the same as those for evaporation, but operating costs would only be about one-half those of evaporation. For the fructose-enrichment scheme, preliminary results indicate that the savings in energy alone for the membrane process would be about $0.01/lb of sweetener produced by the process, or about $20 million annually, for the corn-sweetener industry. (ERA citation 11:040842)