Regular Article

Experimental study of water droplet break up in water in oil dispersions using an apparatus that produces localized pressure drops

¹ PETROBRAS – Petróleo Brasileiro S. A., CENPES/PDDP/TPP, Av. Horácio Macedo 950, Cidade Universitária, Ilha do Fundão, 21941-915 Rio de Janeiro, RJ, Brazil
² UFRJ – Universidade Federal do Rio de Janeiro, Escola de Química, Av. Athos da Silveira Ramos 149, Cidade Universitária, Ilha do Fundão, 21941-909 Rio de Janeiro, RJ, Brazil
³ UNIFEI – NUSEC – Núcleo de Separadores Compactos, Instituto de Engenharia Mecânica, Av. BPS 1303, 37500-903 Itajubá, MG, Brazil

^* Corresponding author: fabriciosoares@petrobras.com.br

Received: 17 July 2018
Accepted: 22 October 2018

Abstract

Oil production facilities have choke/control valves to control production and protect downstream equipment against over pressurization. This process is responsible for droplets break up and the formation of emulsions which are difficult to treat. An experimental study of water in oil dispersion droplets break up in localized pressure drop is presented. To accomplish that, an apparatus simulating a gate valve was constructed. Droplet Size Distribution (DSD) was measured by laser light scattering. Oil physical properties were controlled and three different break up models were compared with the experimental results. All experimental maximum diameters (d_max) were above Kolmogorov length scale. The results show that d_max decreases with increase of energy dissipation rate (ε) according to the relation d_max ∝ ε^−0.42. The Hinze (1955, AIChE J.1, 3, 289–295) model failed to predict the experimental results, although, it was able to adjust reasonably well those points when the original proportional constant was changed. It was observed that increasing the dispersed phase concentration increases d_max due to turbulence suppression and/or coalescence phenomenon. Turbulent viscous break up model gave fairly good prediction.