ABSTRACT
This chapter examines some operating schemes in which the flow pattern is more complex and involves recycling and flow reversals. Chromatographic flowsheets aimed at reducing the shock effects are thus likely to lead to globally less irreversible processes, and ultimately to less diluted products and less costly downstream separation of the eluant from the product. Since the operation involves recycle, the first cycles of such an operation will be different from subsequent cycles and from the cyclic steady state. In mixed recycle chromatography, some separation is lost when the recycled part of the chromatogram is lumped into one fraction, itself being mixed with fresh feed. The recycle is made of a single fraction, which is not mixed with fresh feed, but instead injected before the fresh feed. The set of nonlinear equations can be linearized by a suitable transformation, in a sense a generalization of the hodograph transform.
