Treated sewage water as make-up to the cooling tower requires novel approaches to control potential cooling water problems common to refineries besides meeting environmental regulations. An intensive field study was conducted to evaluate the effectiveness of non-chromate treatment programs. On-line cleaning of the exchangers occurred prior to instituting the new chemical treatment program. Low carbon steel corrosion rates with minimal deposition was achieved. Microbiological fouling was controlled with chlorination and non-oxidizing biocide program. Field results are presented which compare the efficacy of these proprietary treatments to control corrosion and inhibit scale and fouling. Analytical results which provide a comprehensive performance evaluation of a new non-chromate chemical treatment program are presented.
Keywords: cooling tower, chromate, sewage water, corrosion, scaling, microbiological fouling, heat exchanger, phosphate, cycles of concentration, chlorination, non-oxidizing biocide.