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The effect of different polymeric fibers on non-Brownian oil drop steady-state bed coalescence was investigated. Three polymeric low-energy smooth fibers were used: polyethylene, polyester, and polyurethane. The oil-in-water system was used as the model of an unstable emulsion, with the drop size smaller than the pore size. Experiments were carried on geometrically similar beds over a wide range of bed permeability (porosity) and a wide range of fluid velocity, from 16 to 70 m h -1 . The bed coalescence efficiency was followed via the effluent oil concentration and critical velocity. The unexpectedly large differences in critical velocities obtained on the investigated materials correlated well with the critical surface tension.

The effect of fibrous bed permeability on the efficiency of steady-state coalescence was investigated. Bed permeability was changed by compression of polyurethane fibers. The effect of bed permeability was followed based on the effluent oil concentration and critical velocity. An oil-in-water system was used as the model of unstable emulsion, with the drop size smaller than the pore size of the fibrous bed in all experiments. Different fluid velocities, bed lengths, and fluid-flow orientations were applied. The results indicate the existence of two regions of dependence, with a break point at a defined range identified as a critical one. Empirical equations were derived by describing the effluent concentration and critical velocity as a function of the bed permeability and length.

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This paper investigates the separation possibilities of model emulsion oil-in-water using polypropylene fibre bed coalescence. Experiments were carried out over a wide range of physicochemical characteristics of mineral oils, bed permeability and operating fluid velocities. The aim of this study was to analyze the influence of the dispersed oil phase nature and of the bed geometry on the separation efficiency. From the obtained results, it can be concluded that polypropylene fibers in the broadest studied range of bed permeabilities and fluid velocities, effectively separate oil that is highly polar. On the contrary, for the other two investigated oils at low values of bed permeability a region was detected in which the coalescer is incapable to operate. It has to be emphasized that the polypropylene fibres efficiently separate all three investigated oils at the highest studied bed permeability.