May 22-27, 2016
In the Fluid CokingTM process, heavy oil is sprayed into a downward-flowing fluidized bed of hot coke particles. A good liquid distribution on the particles is essential to achieve a high yield of desirable liquid products and avoid operating problems. This presentation shows how to modify local bed hydrodynamics to improve liquid distribution.
The distribution of the injected liquid in the bed can be improved by either increasing the atomization gas flowrate or, preferably, the local fluidization velocity. Study of nozzles at different locations and inclinations identifies the dominant effects of bed hydrodynamics at the nozzle and jet tips on the distribution of liquid on solid particles. Experiments with a moving nozzle, to achieve a relative velocity between spray nozzle and fluidized particles, show that increasing the relative velocity improves liquid distribution.
A model for the interactions between sprayed liquid and fluidized is proposed. When a gas-liquid spray enters a fluidized bed, it forms a jet cavity that expands as atomization gas and bubbles enter the cavity and contracts as large bubbles are periodically released from the jet tip. The model assumes that the injected liquid mixes with the solid particles displaced by the jet expansion. The model shows how increasing either the atomization gas flowrate or the local fluidization velocity improves the liquid distribution by shortening the jet expansion-contraction cycle. The model also explains how the motion of the spray nozzle relative to the fluidized bed can improve liquid distribution by preventing wet solids accumulation near the jet cavity.
Maryam Mohagheghi, Franco Berruti, and Cedric Briens, "Impact of local fluidized bed hydrodynamics on interactions between particles and gas-liquid sprays" in "Fluidization XV", Jamal Chaouki, Ecole Polytechnique de Montreal, Canada Franco Berruti, Wewstern University, Canada Xiaotao Bi, UBC, Canada Ray Cocco, PSRI Inc. USA Eds, ECI Symposium Series, (2016). http://dc.engconfintl.org/fluidization_xv/49