Ultra pure water process and apparatus

Abstract

Abstract Deionized pretreated supply water is stored in a storage unit, and a part of the stored water is recirculated through a pure water recirculation loop. The recirculated water is polished in polishing demineralizers to an electrical resistivity at the circulating temperature equivalent to 18 megohm electrical resistivity at 25*C. A proess portion of this polished water is heated to about 170*F. in a heat exchanger while retaining the 18 megohm equivalent resistivity and delivered to one point of use and then discarded from the recirculation loop. The remainder of the recirculating water is returned to storage, either directly if not used or after reclamation following use as process water. The heat exchanger preserves the ultra pure quality of the water in the 18 megohm equivalent resistivity range by a technique of indirect heating in a coil of inert plastic tubing which is immersed in a body of liquid heated by an immersion heater. The high velocity of the water in the recirculation loop prevents degradation of the quality of the water by minimizing the time of contact with the conduit structure of the recirculation loop. The storage unit has sufficient capacity to make the flow balance substantially non-critical and to provide reserve capacity for the quantities needed for process use. The storage unit and the high quality deionized pretreated water permit the polishing demineralizers in the recirculation loop to be sized for flow rather than for capacity and also permit equipment in the pretreatment supply to be replaced or repaired without interruption of flow in the recirculation loop.

Inventors

• 👤 Terry Lee Faylor
• 👤 Roger W Martin

Bibliographic Details