the raffinate flowrate waveform would change due to the asymmetric nature of the two groups of vessels the flowrate through the remaining three vessels in the group would be increased as much as 33 during some process steps a factor which must be considered to prevent fluidization of the adsorbents and or fluid shocks in the piping and or valving systems in alternative configuration of the present invention the modules are separated into four groups and are each operated 90 degrees out of phase fig2 shows that the resulting raffinate flowrate varies between about 2 000 and 6 000 a ratio of about 3 1 this is roughly half the flowrate variation experienced in the first embodiment where two groups of modules operate 180 degrees out of phase and one sixth the variation of the prior art methods although this flowrate variation reduction is impressive it reduces the number of modules per group to two for the example of an eight module system if one module must be repaired the change in flowrate for he other module in the group would be 100 during some cycle steps a factor to be considered in designing the vessels and their interconnecting valves and flow conduits in a further alternative configuration of the present invention eight groups of modules are employed with their cycles offset by 45 degrees this yields only a modest decrease in flowrate pulsation compared to four groups and results in even larger changes in flowrate should a module require repair in the example of the eight module.