Case Study

Case Study: Baltimore Gas and Electric-Calvert Cliffs Nuclear Deoxygenation System

Source: 3M Separation and Purification Sciences Division
Liqui-Cel Membrane Contactors from Hoechst Celanese Corporation are being used to deoxygenate the high purity makeup water at BG&E Calvert Cliffs Nuclear Plant in Lusby MD. Ecolochem, Inc., headquartered in Norfolk Virginia, designed, built, and now maintains the make-up water treatment system under a service contract. Ecolochem specializes in water treatment service contracts for emergency, short term and long term needs.

System Design
Ecolochem customized the make-up water system to meet the stringent make-up water quality needs of BG&E. The 100-300 gpm make-up system was installed and started up in September of 1996. The water treatment system consists of a two pass, polyamide membrane RO system, three step ion exchange polishing and a state-of-the-art deoxygenation system.

The deoxygenation system consists of three Liqui-Cel Membrane contactors. The contactors contain thousands of microporous hollow fiber membranes. The hydrophobic membrane acts as an inert support structure that allows the gas and liquid phase to come into contact at the membrane's pore. By altering the concentration and pressure of the gases in contact with the water, gases can be selectively dissolved or removed from the water.

The contactors on the system are valved so that they can be operated in a two in parallel feeding one in series configuration or a three in parallel configuration. Both configurations are designed to operate under vacuum. Vacuum is drawn on the bottom lumen side port of each contactor. In this custom design, the dissolved oxygen and TOC levels are routinely lowered to less than 100 ppb. The contactors are followed by Ecolochem's patented catalytic DEOX® process. This process lowers the dissolved oxygen to less than 1 ppb. This design represents one of many ways Liqui-Cel can be incorporated into a hybrid deoxygenation system.

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3M Separation and Purification Sciences Division