Overrun Computation

For WAC-SAC or WBA-SBA resin couples in demineralizers, WAVE will calculate the overrun to increase the load on the strong resin by increasing the ionic leakage from the weak resin. Depending on the options previously specified, WAVE will adjust the overrun in order that:

• The total quantity of chemical meets minimum recommended stoichiometric ratio.

  When the “Length of Operating Cycles” and the regenerant “Dose” are specified, respectively, in the IX Initialization Window and in the Product Quality and Regenerant Dose Window, WAVE calculates the amount of regenerant required based on strong resin. However, most of the ions are picked up by the weak resin. If there is not enough regenerant left over for the weak resin, then WAVE ‘over-runs’ to increase the load on the strong resin and the total quantity of regenerant needed. WAVE adjusts the overrun so that there is sufficient chemical to ensure that both resins are well regenerated (which also gives the best match of capacity and hydraulics).
  

• The total volume of resin (weak + strong combination) is minimized.

  When the “Length of Operating Cycles” and the “Regeneration Ratio” are specified, respectively, in the IX Initialization Window and in the Product Quality and Regenerant Dose Window, the amount of regenerant is given by the ionic load and the Regeneration Ratio. In this case, WAVE adjusts the overrun in order to minimize the total volume (weak + strong) resin.

• Weak resin potential run time and strong resin potential run time are comparable.

  When the Length of Operating Cycle is to be determined (e.g. Evaluating Existing Plant mode), WAVE adjusts the overrun so that weak resin potential run time and strong resin potential run time are comparable.

WAVE also provides the user with the option to input the amount of over-run by clicking on the radio button for “Manual” in the Overrun Computation box.