Delayed coking in the oil & gas industry

The Delayed Coking process is applied to the residual heavy oil, also called residuum feed, which emerges from the bottom of the vacuum distillation column. Via the bottom feed from a further fractionator column, this is fed, with steam, to another furnace and into coke drums. This cracks the heavy, long chain hydrocarbon molecules into coker gas oil and solid petroleum coke. The solid coke deposit remains in the coke drum, and the gas oil and lighter components in the vapour phase are fed back to the fractionator, to separate out the light gas oil, heavy gas oil and naphtha.

One coke drum might be filled with solid coke deposits in about 24 hours: the drums are installed in tandem, so the flow can then be switched to the second drum. While the second drum is filling, the top and bottom heads of the first drum are removed and the solid petroleum coke is removed with a high pressure water nozzle. Refineries might have multiple sets of these drums – which can be up to 45 meters in height.

KROHNE offers high temperature ultrasonic flowmeters that can tolerate the high temperatures of the feed of residual oil feed, which can be up to 500°C. One of the major benefits of the ultrasonic meter over the traditional wedge type meters is the obstructionless design of the flow tube, which prevents any clogging of the meters. Other delayed coker instrumentation from KROHNE includes ultrasonic and vortex flowmeters suitable for high temperature steam applications, and level measurement systems for the separators.