A MAINTENANCE STRATEGY FOR HEAT-TRANSFER EQUIPMENT SUBJECT TO FOULING- A PROBABILISTIC APPROACH

Fouling of heat transfer surfaces introduces a major uncertainty into the design and operation of heat transfer equipment. After a brief dis cussion on impact of fouling, we present and discuss a stochastic appr oach to the analysis of fouling models. In view of the performance ind icator (U/U-c) of the heat exchangers, a maintenance strategy for plan ned maintenance schedules is presented. Various scenarios of reliabili ty based maintenance strategy are introduced. The strategy is explaine d in terms of the scatter parameter (root alpha) of the time-to-foulin g distribution corresponding to a critical level of fouling, and the r isk factor (p) representing the probability of tubes being fouled to a critical level after which a cleaning cycle is needed. In addition, t he cost implications of the above mentioned strategy are explained and their impact on heat exchanger maintenance is highlighted.