Foaming and foam overs are problems frequently encountered in the delayed coker drum. Inadequate foam control can cause foam overs which contaminate valuable overhead coker products as well as potentially plug overhead lines. The University of Tulsa Refining Technologies Group studies foaming through two unique devices- a gamma densitometer installed around the steel coker drum that gives an indication of foaming by measuring the density throughout the length on the coker every 1.5 minutes and a continuous quartz reactor that gives a visual indication of foaming using an NIR camera. From these units, the effects of feed rate, temperature and pressure recorded in literature have all been observed.
In addition, it has been observed that paraffinic feedstocks foamed more eagerly and aggressively than aromatic feedstock. Also, the tendency of foaming to occur during steam stripping (re-foam) is reduced if denser coke beds are made. The tendency for re-foam was observed to decrease as pressure or temperature increased. A foam model was built and is continually enhanced to include new findings as well as account for AF decay and foam regrowth. The effect of recycle is also incorporated in the model.
Understanding the causes and possible prevention of out-of-control foaming, re-foams, AF effectiveness and decay will help optimize the coke drum to minimize problems caused by foaming.
Quartz Reactor with NIR Camera
The Quartz reactor enclosed in a nitrogen purged shielded box is equipped with an NIR camera and video recording capability. It is used to study the foaming tendency of vacuum residues. Foam height, foam collapse, bubble size and foam sample collection are some of the unique features of this reactor.
Specifications
•Online gas measurement/ analyzer
•Pressure capability up to 40 Psig
•Maximum skin temperature 1100 oF
•Flow Range 1.2 – 5 kg/hr
•Typical test duration 2+ hrs
