(135a) Monitoring and Analysis of Inorganics Breakthrough in Refinery Pre-Heat Trains

Monitoring of crude oil fouling in refinery heat exchanger typically focus on the gradual decay of thermal performance based on measured temperatures, heat duties or, most commonly, fouling thermal resistances. Such indicators, however, are inherently unable to provide information on the extent, location and composition of the fouling deposits, and therefore to successfully diagnose the underlying causes. The development of monitoring and analysis methods capable of discriminating such effects is particularly important when fouling is due breakthrough of inorganic foulants into the hot end of the preheat train, where organic deposition is usually assumed to be the dominant mechanism. Such problem may be a result of desalter malfunctioning, changes in feedstock or unsuitable management of operations. Here, a novel model-based monitoring and analysis approach is presented. It enables to improve the understanding on how complex deposit structures involving both inorganic and organic species affect the thermo-hydraulic performance of heat exchangers. From an operational stand point it allows the use of primary plant measurements to early detect, and diagnose the underlying causes. Examples are presented combining simulation, industrial plant data and analytical characterization of the deposit.