Modeling the thermo-hydraulic performance of direct fired heaters for crude processing

Although fouling in heat exchangers for crude processing has received much attention in recent years, the problem still remains unsolved and the economic losses associated to it are significant. Development and application of fouling models due to coke deposition on the heat transfer surface have been achieved with a high degree of certainty for situations where single phase occurs. Fouling rates in systems where two phase flow takes place, as in fired heaters, have been yet studied little. In this work a fouling rate model is adapted to the case of two phase flow conditions and used to predict the thermo-hydraulic behavior of fired heaters. The model is used to predict how fuel consumption is increased as the thermal resistance builds up on the heat transfer surface; additionally, production losses as a consequence of increased pressure drop are determined.