Manufacture of stable bimodal emulsions using dynamic mixing

A process for preparing a bimodal emulsion of viscous hydrocarbon in water includes providing a stream of water at ambient temperature; providing a liquid additive that tends to gel when mixed with water at temperatures less than a gelling temperature TG; heating the stream to provide a heated stream at a temperature TC which is greater than ambient temperature and less than the gelling temperature TG; feeding the heated stream to a mixer having a mixer inlet so as to impart energy to the heated stream; adding the liquid additive to the heated stream downstream of the mixer inlet, whereby the liquid additive mixes with the stream and the energy inhibits gelling of the liquid additive to provide a substantially homogeneous solution of additive in water. The solution is then divided and used to make two different droplet sized emulsions which are mixed to form the bimodal emulsion.