May 22-27, 2016
Fluid CokingTM is a process to upgrade heavy oils through thermal cracking. Oil is injected in a downward-flowing bed of hot coke particles, where it heats up and cracks into smaller vapour molecules. The down-flowing coke particles are sent to a burner where they are reheated and send back to the reactor to provide heat for cracking reactions. Liquid sprayed with atomization gas into a fluidized bed forms a jet cavity that absorbs bubbles from the bubbling bed and periodically releases a large bubble from its tip. The jet penetration length, thus, cycles. With a faster jet cycle, the liquid is distributed more uniformly inside the bed, which is highly desirable. Poor liquid distribution increases the formation of wet agglomerates that slow down the coking reactions and lead to operating problems in commercial Fluid CokersTM.
A novel method is proposed to measure the jet penetration and cycle time in large, room-temperature fluidized beds. It is applied to the study of jet cavities from commercial-size spray nozzles, with a liquid flowrate of 180 kg/min with a sand bed of 8 tonnes. Six cameras-probes are positioned along the jet cavity. Computerized analysis of the resulting videos shows that the average jet penetration length and cycle time is affected by fluidization velocity and atomization gas flowrate.
Measuring the evolution of the bed electrical conductance provides the rate at which water is released from the wet agglomerates. This study shows how liquid distribution can be improved by adjusting jet penetration and cycle time.
Francisco Sanchez Careaga, Cedric Briens, and Franco Berruti, "Measurement of penetration and cycle time of jets from an industrial fluid coking spray nozzle" 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/77