Monitoring and assessment of an industrial antifouling treatment. Seasonal effects and influence of water velocity in an open once-through seawater cooling system

• Fouling growth in a condenser of a power plant cooled by seawater was evaluated.
• The antifouling treatment applied by the power plant reduced the amount of fouling.
• The warmer seasons (spring and summer) were more prone to fouling growth.
• The water flow velocity affects the fouling quantity and its composition.
• The parameter Rf resulted very useful for monitoring the fouling progression.

The fouling is one of the main problems affecting industrial heat exchangers using water from natural sources (lakes, rivers and sea) as the cooling agent. Negative consequences of the fouling formation are the reduction in heat transfer, loss of cooling efficiency, premature deterioration of facilities and increased operation and maintenance costs. In order to minimize this undesirable phenomenon and its effects, antifouling treatments are applied to reduce the accumulation of deposits. A major concern among industrial facilities is the correct choice of a suitable antifouling treatment and its optimization in order to keep the cooling system in optimal conditions and, at the same time, minimize harmful discharges to the environment. This study evaluates the development of fouling in a condenser of a combined cycle power plant, cooled by seawater under actual operating conditions, which means: irregular chlorine treatment, seasonal influence and fluctuation of flow rate according to the number of circulating pumps in operation. The aim of the study was to determine the best operating conditions for improving antifouling treatment. The experiments were carried out in a pilot plant simulating the industrial condenser and operating as side-stream monitoring device on the cooling system while drawing water from the same point than the power plant. Fouling progression throughout an annual cycle and under actual operating conditions was monitored and evaluated. In all the seasons, the chlorine-based antifouling treatment reduced the amount of total solids by approximately 80–85% compared to the control. Control tubes as well as the rest of the test tubes, presented the maximum accumulated fouling in spring, while the lowest quantity of fouling was obtained in winter. The results under the different operating conditions showed that both, the solids accumulation as well as the heat transfer resistance were higher than the rest, when low water velocities were used. Furthermore, the circulating water flow rate affected the composition of the deposits.