Improving performance of simulated moving bed chromatography by fractionation and feed-back of outlet streams

Simulated moving bed (SMB) chromatography is an important technique for the continuous separation of valuable products. Recently suggested process modifications have shown the potential for further improvement. In this work, a concept is presented that combines non-permanent product withdrawal at one or both outlet ports (leading periodically to a "product" and a "non-product" fraction) with an internal recycle and re-feeding of the "non-product" fraction in alternation to the original feed mixture. Using simulation studies for linear and non-linear isotherms, it was shown that in terms of process performance and product recovery, this fractionation and feed-back approach (FF-SMB) is superior to both the conventional SMB process as well as to a previously reported fractionation and discard strategy.