Monitoring of Important Variables Affecting the Formation of Fouling in Crude Oil Heat Exchangers

Conventional methods for determination and monitoring of the total thermal resistance of fouling are based on computing the overall heat transfer coefficient U over time. Heat exchanger cleaning schedules are developed using historical process data on the periods when the thermal resistance of fouling has become too high. There are many different variables of the preheating process that determine the actual rate of fouling build-up in crude oil heat exchangers, namely: flow velocities of the fluids in both shell- and tube-side of exchanger; wall temperatures of the exchanger tubes and the shear rates at the tube surfaces. In this paper, using data records acquired during 5 y of operation of a heat exchanger network coupled with a Crude Distillation Unit, the monitoring of those variables is discussed and their influence on fouling growth is estimated.