Most heat exchangers are already low minimum approach temperatures; thus, there is little scope to increase the heat duty of the existing exchangers by merely adding surface area or intensifying heat transfer.
Also, the sequence of heat exchangers is thermodynamically correct
with higher-temperature hot streams providing heat to crude at higher temperature.
The project goal was to achieve the required throughput targets
with minimal modifications in the existing equipment and piping.
It was very critical to the project to minimize capital investment
and keep the modifications simple.
Since the primary objective of this study was debottlenecking issues rather than energy conservation, an increase in furnace load within its limits was considered to minimize modifications.