Abstract
Open-recirculating cooling water systems are often accidentally contaminated with foreign matters from process side, air, etc., and contaminants sometimes cause various troubles obstructing the safe and continuous operation of these systems.
In this paper, two case histories of different cooling water contaminations are discussed.
Case history 1 involves controlling severe fouling caused by bentonite and alum carryover from clarification pretreatment of make-up water. These materials produced a sticky matter and severely fouled heat exchangers with high water temperature. A special nonionic wetting agent was used to remove the fouling matter from heat exchangers and prevent its additional accumulation.
Case history 2 is concerned with how to control the accidental leakage of acetic acid into the cooling water from a heat exchanger in an acetic acid plant. The high concentration of acetic acid in cooling water increased the corrosion rate by lowering water pH and caused biological fouling by accelerating bacteria growth. Slime removal treatment was accomplished by adding a non-oxidizing, non-foaming anti-fouling agent, in addition to routine countermeasures such as neutralization and blowdown increase. As a result, corrosion and fouling of heat exchangers were sufficiently controlled and kept the heat exchanger in clean condition.
