Simulated countercurrent sorption process employing ion exchange resins with backflushing

A process for separating an extract component from a fluid feed mixture comprising said extract component and one or more raffinate components in a simulated moving-bed system 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 components which process comprises the steps of:

• (a) maintaining fluid flow through a colum of said adsorbent, which column contains at least an adsorption zone, a purification zone, a desorption zone and a buffer zone, each such zone comprising a separation zone having separate separation functions occurring therein, said column also containing a backflushing zone in which backflushing is effected, 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 and the fluid flow in said backflushing zone being in a direction opposite said 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 at a downstream boundary of said zone;
• (c) maintaining said purification zone immediately upstream, with respect to said single direction, of said adsorption 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) maintaining said buffer zone as the nearest separation zone upstream, with respect to said single direction, from said desorption zone, said buffer zone defined as the adsorbent located between the desorbent input stream at a downstream boundary of said buffer zone and a raffinate output stream at an upstream boundary of said buffer zone;
• (f) maintaining said backflushing zone immediately upstream, with respect to said single direction, of said desorbent input stream to said column, said backflushing zone defined by the adsorbent located between said desorbent input stream at an upstream boundary of said zone and a backflushing output stream at a downstream boundary of said zone;
• (g) 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;
• (h) 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;
• (i) withdrawing an extract output stream comprising said extract component and desorbent material from said desorption zone;
• (j) withdrawing said backflushing output stream from said backflushing zone;
• (k) 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, extract output stream, and backflushing output stream to effect the shifting of zones through said adsorbent and the production of extract output and raffinate output streams.