Extended Operation of a Cooling Tower - Sponsored Whitepaper

Solution ProChemTech was requested to investigate the problem on a competitive basis. Following an evaluation of the makeup water quality and plant cooling water system; a new water management program based on use of softened makeup water with appropriate water treatment chemistry was proposed. As softening the makeup water removed all scale forming minerals from the cooling water, the major problem that the new program had to address was the increased corrosivity resulting from cycling of soft water in the cooling tower system. ProChemTech SofTek tm water treatment chemistry was specified to control the known corrosivity problems resultant from use of softened makeup water as it is designed to provide corrosion free operation of cooling towers at high dissolved solids levels with completely soft makeup water.

Following acceptance of the proposal, ProChemTech supplied water softener equipment was installed in early 2002 for 100% softening of cooling tower makeup water. The ProChemTech SofTek water management program was implemented following equipment installation and startup.

System Information The cooling tower system consisted of five galvanized steel, plastic fill cross flow units of 400 tons capacity each banked as one system with a typical load of 1200 tons. The water management program when reviewed consisted of pH control using sulfuric acid with a control point of 7.0, a molybdate traced phosphonate-phosphate based corrosion and scale inhibitor with hydantoin bromine tablets and glutaraldehyde used as alternating biocides, each slug dosed once a week. Cycles of concentration (COC) were maintained at three (3) and analysis of water samples taken during the review indicated that steel and copper corrosion rates were excessive given the levels found in the cooling water. A bypass sand filter was installed with blowdown controlled by conductivity and chemical inhibitor was fed proportional to makeup.