Process innovation in the sugar industry: chromatographic sugar separation using SMB technology

The chromatographic separation of sugar from raw juice was identified as a promising alternative for the current juice purification. Simulated moving bed technology (SMB) was chosen as the most suitable technology on the basis of the purification, limited degree of dilution and increased sugar yield. An adsorbent was selected which binds sucrose selectively compared to glucose, glutamine and betaine. The binding mechanism on a molecular scale (CH-pi interaction) is weak enough to allow for a sensible desorption strategy. An SMB process model was used to evaluate the performance of the adsorbents. Experiments on the laboratory scale were done using micro-filtration and reverse osmosis. SMB experiments were carried out on pilot scale using the selected adsorbent. A temperature swing resulted in a concentration step during adsorption/desorption. This lowers the energy costs for water evaporation prior to the crystallization process. The process is economically feasible when all identified savings are realized. Important issues are the reduction of sugar losses in the total process, a higher sucrose yield in crystallization as a result of a higher purity, and limited operational costs due to prevention of dilution.