delayed coker

A type of coker whose process consists of heating the residual oil feed to its thermal cracking temperature in a multi parallel pass furnace. This cracks the long chain heavy carbon and hydrogen molecules of the residual oil into coker gas oil and pet coke. Both are in a liquefied form in the mixture as it leaves the furnace and enters the coke drum. In the drum, the coker gas oil vaporizes and separates from the mixture. It is directed to a fractionation column where it is separated into the desirable boiling point fractions. The liquid coke solidifies in the drum as it cools and the velocity slows down. After the drum is full of the solidified coke, the hot mixture from the furnace is switched to a second drum. While the second drum is filling, the full drum is steamed to further reduce hydrocarbon content of the pet coke, and then water quenched to cool it. The top and bottom heads of the full coke drum are removed, and the solid pet coke is then cut from the coke drum with a high pressure water nozzle, where it falls into a pit for reclamation to storage. Larger cokers have several pairs of tandem drums.