Eulerian simulations of liquid distribution generated by chimney and bubble cap distributors

Abstract

• Measurements on flow through single units of industrial gas-liquid distributors. • Liquid flow morphology analyzed using dual-tip voidage probes. • Development of Eulerian CFD model with weighted drag formulation and validation. • Performance analysis of chimney and bubble cap distributor configurations. • Effect of addition of liquid dispersion plates on liquid distribution. Gas–liquid distributors form an integral part of an industrial packed bed reactor, esp. trickle bed reactors used for hydrodesulphurization of liquid fuels. Among several process parameters that influence performance of trickle bed reactors, gas–liquid distributors are of foremost importance. In the present work, we have developed a computational model based on Eulerian two-fluid approach to simulate the gas–liquid flow in widely–varying flow regimes encountered in a distributor unit. The predictions are validated using the liquid distribution measured using high-speed imaging, morphology of gas–liquid flow measured using in–house developed voidage probes, and pressure drop measurements. Owing to the difference in the inherent nature of flow through the standard chimney and standard bubble cap distributors, the liquid discharge pattern, uniformity and symmetry of flow streams, and pressure drop across the distributor were found to be significantly different from each other. Further, the addition of liquid dispersion plates to the outlet of the main distributor unit not only resulted in improved liquid discharge pattern and wider coverage span, but also in a highly dispersed stream. Lastly, the application of the above study and the presented methodology was demonstrated for predicting the gas–liquid distribution through industrial trays, using standard bubble cap and chimney trays.