Coflow regeneration

The consequences of the coflow regeneration pattern become immediately apparent at the start of the next loading cycle. At the top of the column ion exchange is complete giving an equivalent concentration of A ions which then travel unaffected down the bed ... 

As discussed in Chapter 7 (Column Breakthrough and Leakage ) counterflow regeneration designs not only provide for better operational efficiencies compared with coflow systems but leakage residuals are virtually eliminated such that the column effluent quality only begins to deteriorate as the resin begins to truly exhaust. 

The broad overall principles of vessel construction remain the same as for coflow units except for one crucial, and essential, exception. The counterflow mode of operation means that a conventional fixed bed will be unstable during regeneration or service depending upon whether employing upflow regeneration or upflow service respectively. Therefore all counterflow designs incorporate a means whereby the resin bed remains stable and packed at all times. Several hold down techniques may be encountered in installed counterflow plants as illustrated in Figure 10.4. 

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