Overview

Howard M. Feintuch

Kenneth M. Negin

Foster Wheeler USA Corporation
Clinton, New Jersey

The delayed coker is an important residue conversion process, or so-called bottom-of-the-barrel process where residues from heavy, high-sulfur crudes are converted to transportation fuels.

Statistically, in terms of number of units installed and total current operating capacity, it is quite easy to show that delayed coking is the residue-conversion process which is most often used today. In addition, because of its wide commercial acceptance, delayed coking has been referred to as the yardstick against which other, less commercially proven, processes must be measured.2

Despite its wide commercial use, only relatively few contractors and refiners are truly knowledgeable in delayed-coking design, so that this process carries with it a black art connotation.3

The year in which delayed coking was first developed is given in historical listings of petroleum advances as 1928.4 We know that in early refineries severe thermal cracking of residue would result in the deposit of unwanted coke in the heaters. By evaluation of the art of heater design, methods were found by which it was possible to raise rapidly the temperature of the residue above the coking point without depositing the coke in the heater itself. Provision of an insulated surge drum downstream of the heater so that the coking took place after the heater, but before subsequent processing, resulted in the name delayed coking. 5

The next step was to add a second coke drum, which doubled the run length and led to the...