A simple unmixed reservoir was developed for the one column chromatograph with recycle analogous to an SMB (Analog) to replace mixed tanks or a complicated unmixed reservoir. Separation of the 1,1' bi-2-naphthol enantiomers was studied. In the linear range the purity index (PI) of the Analog with mixed tanks is 87.5, PI = 94.8 for the unmixed reservoir Analog, and PIT = 96.9 for the SMB. SMB scaling rules, extended to Analogs, are used to increase the product purities of the unmixed reservoir Analog to match SMEB purities but with lower productivity. Then productivity is increased at constant purity by operating at the maximum allowable pressure drop (15 bar) in each step. After scaling, the unmixed reservoir Analog's productivity was higher than the productivity of a standard SMB (one recycle pump) at the same purities (PI = 96 9), and the mixed tanks Analog's productivity was 3.5 times higher than the standard SMEB, but with a significantly lower purity. (c) 2006 American Institute of Chemical Engineers.