A water droplet size distribution dependent modeling of hydrate formation in water/oil emulsion

Experimental data on chord length distributions and growth rate during methane hydrate formation in water-in-oil emulsions were obtained in a high pressure stirring reactor using focused beam reflectance measurement and particle video microscope. The experiments were carried out at 274.2 K for 10-30% water cuts and agitation rates ranging from 200 to 500 rpm initially at 7.72 MPa. Rapid growth was accompanied by gradually decrease in rate. Free water was observed to become depleted during rapid growth while some water remained encapsulated inside hydrate layers constituting a mass transfer barrier. The apparent kinetic constants of methane hydrate formation and free-water fractions were determined using a newly developed kinetic model independent of the dissolution rate at the gas-oil interface. It was illustrated that continued growth depends on distribution and transfer of water in oil-dominated systems. This perception accords with observations of hydrate film growth on suspended water droplet in oil and clarifies transfer limits in kinetics. (c) 2016 American Institute of Chemical Engineers AIChE J, 63: 1010-1023, 2017