SRINI SRIVATSAN (Amec Foster Wheeler)

Ensure that the following scenarios or standards are met:

*The drum is switched slowly by taking to midpoint and holding for some time, thereby avoiding sudden depressurization of the coke drum.

*There is sufficient preheating so that the drum will be well warmed.

*Avoid having residual steam/condensed water in the drum due to incomplete steam free operation by draining completely prior to introducing feed.

*Avoid entrainment of antifoam due to high coke drum velocity. Antifoam loss due to entrainment can be controlled by proper design, optimizing dilution ratios, and possibly using higher viscosity antifoam. Typical antifoam injection should be at the top of the coke drum as far as possible from the coke drum overhead vapor nozzle 180°offset.

*Maintain reasonable outage and monitor level in the drum using a combination of continuous and point (density) nuclear level gages.