Influence of Pre-Heat Train Performance and Fired Heater Design on Fuel Efficiency of Crude Distillation Units

The amount of heat recovery achieved in the pre-heat train used ahead of the fired heater feeding a crude oil distillation unit does not just affect fuel efficiency of the process by controlling the heating that must be undertaken in the fired heater. It can also affect the fouling encountered within the fired heater itself which leads to reduced heat transfer coefficient and increased fuel burn.

Furthermore, geometry and firing arrangements of the fired heater also have an influence on the fouling occurring within the unit.

This paper presents an analysis of the influence of heater inlet and heater geometry on fouling and crude oil residence time within the heater.

It is shown that under some circumstances the flow in the first coil of the convective section is single phase. The result is low crude side heat transfer coefficient which leads to high wall temperature and high fouling rates in the convective section of the heater. This is accompanied by higher than necessary residence times. It is possible that these factors lead to excess coking within the heater with coke subsequently being deposited in the column itself.