Effect of spray nozzle design on liquid–solid contact in fluidized beds

In industrial fluid cokers the feedstock, consisting of heavy bituminous hydrocarbons, is atomized with steam and injected into a hot fluidized bed of coke. Good and uniform contact of the liquid droplets with the solid particles is required to provide heat for the cracking reactions while minimizing mass transfer effects. Experiments in a pilot plant coker have suggested that the initial particle/liquid mixing, in the spray jet, is rather poor. Experiments in a X-ray scanner showed that liquid droplets and entrained particles accumulate just below the tip of the jet plume to form agglomerates.An experimental technique was used to quantitatively determine the quality of mixing with a variety of nozzle configurations including several novel designs. By improving spray stability, redistributing liquid droplets to the solids-rich region of the jet and increasing the surface area of the gas–liquid jet-fluidized bed interface, liquid/solid contact is improved.

The effect of spray nozzle design on liquid–solid contact in gas–solids fluidized beds is studied. By improving spray stability, adding periphery gas jets (SS) and an impact device (IP) at the nozzle exit liquid/solid contact is improved. The best nozzle design reduced the amount of feed liquid that formed liquid/solid agglomerates, larger than 1 mm in diameter, from 96.5 wt.% to 10 wt.%.Figure optionsDownload as PowerPoint slide