Performance Evaluation of Polydimethylsiloxane-Solvent Blends as Defoamer for Crude Oil Foam

Abstract

The study is directed at the use of polydimethylsiloxane-based defoamer formulated with different solvent blends that are capable of breaking and preventing crude oil foam. The control or elimination of the foam that arises in oil and gas industrial processes is a crucial factor in the smooth and efficient operation of the plant. Foam can reduce available capacity of processing vessels, and interfere with the efficiency of the process. Foaming problem is common in the three-phase separators in crude oil flowstations; it can result in level control difficulties and carryover of valuable crude oil into the gas scrubbers and eventually to the gas flare, resulting in loss of production. The effectiveness of these solvent blended defoamers in controlling crude oil foam was determined using foam-rise or Bikerman test method. The collapse rates of the foam with the application of each defoamer sample at various treatment rates (10ppm, 15ppm and 20ppm), were observed as against a blank as control. It was observed that at 10ppm treatment, defoamer A had the highest foam collapse rate (0.0108mm/s). At 15ppm treatment, defoamer G had the highest foam collapse rate (0.0110mm/s), and at 20ppm treatment, defoamer E had the highest foam collapse rate (0.0108mm/s). This shows that defoamer A, which is the conventional formulation (i.e. 20 %vol. silicone + 80 %vol. kerosene), had the highest foam collapse rate at the lowest dosage of 10ppm. On the overall, the highest foam collapse rate (0.0110mm/s) was obtained with defoamer G at 15ppm treatment. Defoamer G is 20 %vol. Silicone + 80 %vol. of a (1:1 %v/v) blend of kerosene and crude palm kernel oil. This suggests that the presence of crude palm kernel oil in the solvent blend had a remarkable effect on the crude oil foam collapse rate. Conclusively, the performance of defoamers varies considerably with the kind of solvent or blend of solvents used for the dispersion of the silicone fluid. It is also worthy of note that the treatment dosage of a defoamer, together with the foam collapse rate are key factors that influence the selection of an effective defoamer.