(713d) Controlling Foaming during Thermal Cracking - a Non-Silicon Based Antifoaming Agent
This paper shows how a non-silicon based antifoam is used to control foaming during thermal cracking in a pilot unit delayed coker drum. A vacuum resid with known properties was fed to the 3-inch diameter coker equipped with a gamma densitometer that allows for a transient analysis on foam growth and collapse during the experiment. This non-silicon antifoam; Tire oil, is an aromatic compound that does not contain any contaminants which can affect the downstream units or catalyst. Two modes of AF injection are tested; intermittent and continuous injections (at 0.36 cc/min and 0.18 cc/min after initial injection). Both modes were found to be effective at controlling the foam in the coke drum. The continuous foaming case resulted in a morphology change and liquid yield increased. Two AF concentrations are also tested (a neat injection and a mix with a hydrocarbon carrier) using the intermittent injection mode. Both concentrations were effective at controlling the foam.
The processing capacity of an industrial coke drum utilizing this non-silicon AF may be increased by decreasing the zone used to impede foamovers as a result of the eliminated risk of catalyst poisoning typically caused by foamover of silicon containing liquid. This increases the profitability of the delayed coker process.