Entrainment and Stability of a Horizontal Gas-Liquid Jet in a Fluidized Bed

Abstract

Fluid coking is a non-catalytic process where heavy hydrocarbon feed, sprayed using jets into a fluidized bed reactor, cracks upon contacting hot coke particles and produces valuable volatile fractions. It is estimated that the Alberta tar sands contain 1.7 trillion barrels of oil, equivalent to 35% of the world’s crude oil reserves, of which the majority is processed using fluid cokers. Important parameters that affect the yield of fluid cokers include the feed jet stability and therefore its ability to entrain and mix the injected feedstock with the fluidized coke particles. To this purpose, this study investigated the effect of the use of various types of draft tubes, placed downstream of the feed jet to enhance mixing, on solids entrainment and jet stability.Specifically, it has been demonstrated with the use of a gas-liquid and gas-only jet that an optimum distance exists between the nozzle and draft tube for entrainment of solids. For both cases, this optimal distance occurs as the jet touches the draft tube wall. However, for a gas-only jet this occurs at a shorter distances due to the increased angle of expansion. The angles of expansion were confirmed using triboelectric probe measurements. It has also been shown that the shape of the inlet to the draft tube will have an effect on the rate of solids entrainment as will the presence of pulsations in the jet.