(93f) An Integral Technique of Monitoring Localized Coking in Refinery Fired Heaters

A typical refinery consumes about 445,000 Btu/barrel of crude processed, most of which is provided by process heaters. The recent trend of high utilization in the refining industry enforces operating of process heaters close to, or beyond, design capacities. Argonne is pursuing a long-term project for developing a pipe-flow two-phase flow process model, with the objective of predicting localized coking in straight and in U-bend regions. The threshold fouling developed for crude oil is incorporated into the process model to determine localized coking in crude and resid refinery heaters. The prediction results show localized variations of coking in straight and U-bend regions. An integral technique consists of this fired heater model and high temperature fouling/coking unit to monitor change in coking trend of the feedstock. The coking data from the fouling/coking unit are feedback into the prediction model. This integral technique combined with discrete as well as infra-red measurements of the tube metal temperatures will provide a real-time monitoring of the fired heater.