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In my CDU unit, there are two type of feedstocks -- sour crude and sour condensate. I noticed both Units have same configurations -- except CDU have desalters and charge heater while Condensate Fractionation Unit does not have them. While crude feed is vaporized up to 60% before charged into CDU column (360degC), condensate feed is heat up only up to 140degC where it is still 100% liquid phase.
My question is,
1) Why in CFU configuration, it does not requires Charge Heater at upstream of Condensate Fractionation column?
2) What is the factor determining the vaporization rate of condensate/ crude feed into the fractionation column?
 
Answers
13/04/2017 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
Stabilizing or distilling condensate into fractions is much simpler than fractionating crude oil, even if it is very light crude. A crude oil will crack when heated above a maximum temperature. That maximum is different from crude to crude. The percent vaporized at the heater outlet depends entirely on the crude composition and the pressure drop through the system. With a feed heater, less bottoms product can be achieved than with a reboiler, thus the chosen configuration.
Distilling or fractionating condensate is more like separating propane from butane by distillation in terms of process configuration. A reboiler is the better configuration. Percent vapor at the column inlet depends on the extent of preheat and operating pressure.