Bypass chromatography – design and analysis of an improved strategy for operating batch chromatography processes

Design of bypass-simulated moving bed chromatography for reduced purity requirements

“…In other words, the highest productivity ratio, for the case of an infinitely efficient column, is obtained when the SMB is designed to provide an extract that corresponds to the target purity and the raffinate is pure followed by blending the feed with the raffinate to obtain the target purity. This observation is consistent with the results obtained for single-column bypass chromatography [Siitonen et al, 2012]. Summarizing, the maximum ratio of the BP-SMB and RP-SMB productivities, operated at points P and R, respectively, is given by:…”

“…These are quite interesting results that show that the BP-SMB does not provide any advantage in terms of solvent consumption. This again is fully consistent with the observations made for bypass-chromatography [Siitonen et al, 2012]. Specifically, the desorbent requirement in region 4, where productivity advantages are seen does not disadvantage the BP-SMB in terms of desorbent requirement, while providing the additional possibility to improve productivity.…”

“…This configuration, that will be referred to as "Bypass SMB" (BP-SMB), provides additional degrees of freedom to produce low purity products by over-purifying them with the feed to reach the target-purity. Siitonen et al, described a single-column version of this concept (bypass chromatography) and developed explicit design methods for systems that follow linear and Langmuir isotherms [Siitonen et al, 2012[Siitonen et al, , 2013. They also explored conditions under which bypass chromatography provides advantages over a chromatographic separation that directly provides products that meet the target purities.…”

Design of batch chromatography for separation of binary mixtures under reduced purity requirements

“…It is similar to that used by Golshan-Shirazi and Guiochon [2] for systems with Langmuir isotherm in a special case where only the second component is the target. A similar method was also used by Sainio and Kaspereit [14] to design mixed-recycle steady state recycling chromatography (MR-SSR), by Siitonen et al [16] to design MR-SSR with an integrated solvent removal unit, and by Siitonen et al [17] to design bypass chromatography. In this work, however, the approach is applied to batch separations where two product fractions without generation of waste or recycle fractions are desired.…”

A Modular Framework for the Modelling and Optimization of Advanced Chromatographic Processes

“…For example, operating concepts, such as closed-loop recycling [4,5] or steady-state recycling (SSR) [6][7][8] incorporate different strategies for the recycling of unresolved fractions from the column outlet back to the inlet with the aim of improving yield, solvent consumption and/or productivity [7]. If purity requirements are limited, bypass streams can be advantageous [9]. Moreover, the use of multiple columns gives rise to various concepts ranging from clever series or parallel arrangements of multiple batch columns [10,11], over pseudo-continuous processes, up to the many variants of the powerful continuous simulated moving bed (SMB) concept.…”