How do ion exchange resins work?
Two or three purification vessels or “columns” are usually required. These can best be described as “lead”, “lag” and “standby” columns. The lead column does the bulk of the polishing and the second (lag) column does the trace polishing. The standby column is used in case of emergency or when the lead column exhausts. Raw biodiesel flows through the lead and lag column. When the effluent of the second column contains increased glycerine levels, this column then becomes the lead column. If available, the standby column then goes into the lag position and the original column goes into standby.
