Design of in-line emulsification processes for water-in-oil emulsions

The fabrication of water-in-oil emulsions is a process with widespread applications in formulation engineering. The most common process approach is to use a stirred vessel provided with a high speed dispersing impeller or a rotor-stator head and operated in batch or semi-batch mode. The mean drop size and the drop size distribution are usually correlated by the properties of the surfactants and the specific mechanical energy dissipated by the mixer among others. The present paper addresses an application in the oil industry: the large-scale manufacturing of a fine water-in-oil emulsion. Instead of using a tank-based operation, the idea is to create the emulsion in line and operate the process in a continuous mode. Several commercial in-line dispersing technologies are available and the purpose is here to determine the process and dispersing technology parameters that make possible the fabrication of a stable emulsion. Likewise in stirred tank, it is shown that apart from the energy dissipation rate, the kinetics properties of the surfactants and the process configuration also play a major role in obtaining a stable emulsion.