Gray and Impaired Water Cooling in Surface Condensers and Heat Exchangers

In recent years, concern over the continued use of limited fresh water supplies or similarly, cooling towers and their essential makeup, high maintenance and associated chemical treatment requirements has spawned a clever, yet dramatic change in powerplant surface condenser and heat exchanger cooling. The paradigm shift away from the established and typical toward the unconventional has produced an innovative and non-traditional cooling water source for surface condensers and heat exchangers. Pundits suggest water shortages will increase the amount of water reuse (Chart 1) in the US from a current estimated 1.7 billion gallons to an estimated 12 billion gallons by the year 2015². Given this dramatic prediction, water reuse, or the reclamation and treatment of impaired or gray water will be driven by and emerge as market incentives joined at the hip by emerging or mandated effluent discharge standards. Without a clear understanding of the legislative and political landscape, regulative complexities that deal with this type of cooling water could conceivably lead to an unattractive environmental legacy. Having duly noted the “trend or aberration” dilemma, this paper will further identify efforts by the municipal wastewater treatment plants to economically process a usable product. We will investigate the impact of ancillary add-on costs absorbed by the electric utility such as secondary filtration and examine an actual case study involving the extensive use of gray water. Finally, the paper will evaluate new operational conditions, emerging new corrosion issues with suggested abatement, metallurgical changes, pollution considerations, maintenance issues and other mechanisms which have forced utilities to develop innovative solutions when employing impaired cooling water sources for the main surface condenser and other heat exchangers.