Development and Field Testing of Polymer-Based Heat Exchanger Coatings

Abstract

In aggressive geothermal environments, heat exchanger equipment capital and maintenance costs are high due to the expensive, corrosion-resistant materials required and to the maintenance involved in keeping the heat transfer surfaces clean. To reduce these costs, the National Renewable Energy Laboratory and Brookhaven National Laboratory have been conducting tests of polymer-based coatings systems. These coating systems protect low-cost carbon steel tubing from corrosion and are formulated to resist the strong attachment of scale, thus facilitating cleaning. Laboratory and field tests of a variety of polymeric coatings under development show that geothermal deposits bond to the most promising coatings as weakly as they do to expensive stainless steels, and the coated tubes can be easily cleaned using conventional hydroblasting methods without damage to the polymer coating.