The vacuum residue feed is preheated and then introduced to the feed zone of the coker fractionator tower. The fractionator bottoms is heated in a carefully engineered multi-pass coker heater furnace to optimal high coil outlet temperatures to minimise the deposition of fouling coke within the furnace tubes. Coking of the feed is delayed until the feed mixture reaches the coke drum.

Within the coke drums, the hot liquid vacuum residue undergoes further controlled thermal cracking at appropriate temperatures and pressures. Petroleum coke slowly builds up in the on-stream coke drums until a designated level is reached, while light hydrocarbons simultaneously leave the on-stream coke drum as overhead products and are routed back to the coker fractionator. In the fractionator, the liquid phase, naphtha and gas-oils are recovered, while the remaining gas phase exits the coker fractionator accumulator. The overhead off-gas from the DCU is routed into the fuel gas system.

When a coke drum is full, it is switched off-line and Petcoke is then removed by hydraulic decoking using a jet pump system. Continuous operation is maintained by switching coke drums once the online drum reaches the expected coke inventory target level. Coke is moved to coke crushers and belts for transfer to interim inventory or to rail car loading via either a bridge crane or large front end bucket loaders.