Solids Entrainment into Gas, Liquid, and Gas-Liquid Spray Jets in Fluidized Beds

摘要

The injection of liquid into a fluidized bed is a crucial step in many processes such asfluid coking, fluid catalytic cracking, or gas-phase polymerization, whose performancegreatly depends on good and rapid contact between the injected liquid and the fluidizedparticles. The liquid spray, created by two-phase (gas-liquid) nozzles, forms a jet, I.e. agas-rich cavity within the fluidized bed. Past studies have shown that good liquid-solidcontact requires a large entrainment rate of particles into the jet, followed by intensivemixing of liquid droplets and entrained particles within the jet. The objective of thisstudy is the experimental measurement of solids entrainment into spray jets. The specificapplication of interest is the enhancement of solids entrainment under conditions relevantto the fluid coking process.A novel and accurate experimental technique has been developed to measure the solidsentrainment from a fluidized bed into two-phase gas-liquid jets, gas jets and liquid jets.The effects of operating conditions of the nozzle (sonic versus subsonic) and of thefluidized bed on the solids entrainment have been investigated. The differences betweenthe mechanisms of solids entrainment for two-phase gas-liquid, gas and liquid jets havebeen analyzed.This experimental tool has been applied to the design and testing of a mixing chamberconsisting of a cylindrical tube placed at a certain distance downstream of the nozzle tip,resulting in a confined, turbulent jet with enhanced liquid-solid mixing properties.