Experimental and Numerical Investigations of Liquid Fragmentation and Droplet Generation for Gas Processing at High Pressures

Abstract

Liquid fragmentation and droplet behaviour was experimentally and numerically studied within this thesis. In the numerical part, a generic transport equation was derived from the Boltzmann equation and was used to extend the population balance framework in order to describe the interaction between the dispersed phase with a continuous phase. Also, a momentum equation for the dispersed phase was proposed.

The population balance framework was used as a starting point for the droplet behaviour modelling, and the conservation equations were solved using the least squares method. The droplet study was focused on the breakage dominant formulation and several breakage and redistribution kernels were analyzed.

An inverse problem technique was used, together with the population balance framework, to find the breakage kernel for a gas–liquid and a liquid–liquid system. Even though the technique predicts a resulting breakage kernel, these types of derivations yield system dependent kernels.

The equations for the droplet description enable a more detailed description of the dispersed phase that requires new kernels dedicated to model the droplet generation from liquid entrainment. For this matter, experiments were run aimed to measure the droplet size distribution after a mass entrainment event.

The experimental part of this thesis consisted of collecting droplet data for a light hydrocarbon system, featuring a surface tension of the order of 20 mN/m, under two different geometries which were specifically selected to simulate liquid entrainment inside the gas scrubbers: the first set of experiments were performed for liquid entrainment from a stratified film and the second dataset was collected for droplet entrainment from a wetted wire with a perpendicular gas flow passing the wire.

The resulting droplet size distributions from both experiments are presented and compared with droplet data from other authors which used different geometries (i.e. annular flow). Two correlations used to predict the mean droplet size after entrainment were tested and a new correlation is presented.