MINIMIZATION OF CORROSION USING ACTIVATED SODIUM-BROMIDE IN A MEDIUM-SIZE COOLING-TOWER

The cooling tower at the Albemarle Process Development Center in Baton Rouge, Louisiana, historically used chlorine as a biocide in combinat ion with phosphorus-based corrosion/scale inhibitors. Although this re gimen provided biocontrol, sludge and iron buildup was a problem in lo w-velocity, small cross-sectional areas of piping. A general cleanup o f the system was performed in April 1995. This cleanup was followed wi th a switch to a two-component corrosion inhibitor/dispersant package. Alternate biocides were evaluated at this time. Activated sodium brom ide was found to be particularly effective in this tower, which operat es at pH similar to 8.4. Relative to chlorine, the use of activated so dium bromide led to a decrease in general and pitting corrosion on mil d steel. The reduced corrosion appears to be due to a combination of b oth chemical (less attack on passivated metal surfaces) and biological factors (better control of heterotrophic and sessile bacteria). These conclusions are supported by chemical analyses, corrosion meter and c oupon data, dip slides, biological activity reaction tests, and visual observations of the tower sump and heat exchanger surfaces.