TABLE OF CONTENTS The various components that go into a demineralizer, i.e., vessels, distributors, valves, and so forth (Fig. 5-33), must all be designed using good engineering practice for the demineralizer to operate properly. The following subsections provide some general ideas regarding these items.
Skid-Mounted Demineralizer System. Photo courtesy of U.S. Filter.
The flow rate of water or regenerant across the resin should be uniform to prevent channeling or areas of high and low flow. Distributor design is most important. Distributors are usually supplied in a lateral type arrangement so that the spray uniformly covers the entire surface area of the resin. The spray nozzles and piping should be designed to provide the same quantity of water from each opening.
Ion exchanger vessels are rubber lined to prevent corrosion. The rubber lining must be installed properly and spark tested to eliminate any holidays in the liner. If liquid gets behind the liner, where it can attack a localized area of the vessel shell, shell failure may result. Vessels must also be fabricated in accordance with pressure-vessel design codes. This becomes particularly important for on-line conden-sate polishers, which may operate at several hundred pounds of pressure.
The valving arrangement on a demineralizer can be fairly complicated. Valves automatically open and close during changes between service, regeneration, and rinse. Positive shutoff valves such as block valves are recommended so that process fluids do not infiltrate unwanted areas.
Materials for piping, valves, and tanks must...
