Civil Engineering Reference
In-Depth Information
Fig. 18-2.
Cut-away of typical ion-exchange pressure vessel (Courtesy of Infilco Degremont,
Inc.)
Resin volume can be varied by changing the bed depth and the number of contac-
tors. Because maximum raw-water hardness is not within the control of the plant
designer, the only remaining variable is regeneration frequency. If the plant is auto-
matically operated, a minimum regeneration frequency of 8 to 12 hours is suggested.
However, in manually operated plants that have one shift per day, the frequency should
be every 24 hours. Sufficient product water storage to ''average out'' the reduction in
product water flow during contactor regeneration is desirable. Without storage, the
treatment system must be designed to continuously meet distribution system demands
even with one contactor out of service for regeneration.
