Simulated countercurrent sorption process employing ion exchange resins with periodic backflushing

Claim 1

In a process for separating an extract component from a fluid feed mixture comprising said extract component and a raffinate component in a simulated moving-bed countercurrent flow system having simulated movement in but one direction by employment of a stationary adsorbent consisting essentially of an ion exchange resin having a greater selectivity for said extract component than for said raffinate component, the separation mode of such process comprising the steps of: (a) maintaining fluid flow through a column of said adsorbent, which column contains separation zones comprising at least an adsorption zone, a purification zone, and a desorption zone, said zones being serially interconnected with the terminal zones of said column connected to provide a continuous connection of said zones, said fluid flow in said separation zones being in a single direction; (b) maintaining said adsorption zone in said column defined by the adsorbent located between a feed input stream at an upstream boundary of said zone and a raffinate output stream comprising said raffinate component and said desorbent material at a downstream boundary of said zone; (c) maintaining said purification zone immediately upstream with respect to said single direction, of said adsorptive zone, said purification zone defined by the adsorbent located between an extract output stream at an upstream boundary of said purification zone and said feed input stream at a downstream boundary of said purification zone; (d) maintaining said desorption zone immediately upstream, with respect to said single direction, of said purification zone, said desorption zone defined by the adsorbent located between a desorbent input stream at an upstream boundary of said zone and said extract output stream at a downstream boundary of said zone; (e) passing said feed mixture into said adsorption zone at adsorption conditions to effect the selective adsorption of said extract component by said adsorbent in said adsorption zone and withdrawing a raffinate output stream from said adsorption zone comprising said raffinate component and desorbent material; (f) passing a desorbent material into said desorption zone at desorption conditions to effect the displacement of said extract component from the adsorbent in said desorption zone; (g) withdrawing an extract output stream comprising said extract component and desorbent material from said desorption zone; (h) periodically advancing through said column of adsorbent in a downstream direction with respect to fluid flow in said adsorption zone the feed input stream, raffinate output stream, desorbent input stream, and extract output stream, to effect the shifting of zones through said adsorbent and the production of extract output and raffinate output streams; and (i) periodically backflushing said adsorbent by periodically passing a backflush mode stream through said feed input stream as the backflush input stream and withdrawing a backflushing output stream as the backflushing output stream from said column, said backflushing output stream being upstream, with respect to said single direction of said feed input stream to effect the periodic backflushing of said adsorbent located between said feed input stream and said backflushing output stream.