Collision Characterization of Mixed Hydrocarbon Liquid Droplets with Polyethylene Particles

Abstract

In the gas–solid fluidized bed with condensed liquid spray applied to ethylene polymerization, the collision characteristics of condensed droplets and polyethylene particles play an important role in determining the heat transfer and product properties. High-speed photography, noninvasive laser heating, and a quasi-circle data processing approach are employed to investigate the collision interaction between the hydrocarbon liquid droplets with different mixed compositions and a single polyethylene particle, under different particle temperatures and droplet Weber numbers. The results have found that the hydrodynamic behavior and heat transfer characteristics of the liquid films formed during the droplet–particle collision are more dependent on the liquid components with a higher mass fraction. The behavior of the liquid films is divided into two types, named the directly slip and recoil, the latter of which is beneficial for enhancing heat and mass transfer efficiency. Especially under low Weber numbers, the long-time recoil only occurs during the evolution of 1-octene and n-hexane/1-octene mixed liquid films. Generally, as the Weber number rises, the temperature thresholds required for recoil appearance increase for all kinds of liquid films. It is indicated that the necessary conditions for recoil are low inertia force and high temperature.