Baffle plate configurations to enhance separation in horizontal primary separators

Horizontal separators use gravity settling to separate oil from water and o ther components of oil well riser streams. Inlet designs can induce non-uni form liquid flow across the separator's cross section with a substantial zo ne of re-circulation. To optimise oil/water separation, the Liquid should a chieve near to plug flow, so that both phases experience a limited range of residence times. Internal fittings to improve flow uniformity have been in vestigated. A single perforated plate across the flow near the inlet increased uniformi ty of axial velocity across the separator cross section downstream of the b affle. A 10% free area baffle gave better uniformity of flow across the cro ss section compared to baffles having 5, 15 and 20% free areas. For a fixed free area fraction, the baffle hole size had only a small effect on the fl ow distribution even though the hole size was varied sufficiently to cover both laminar and turbulent flow through the holes. Two baffles gave further slight improvement in flow uniformity but only whe n the baffles were very closely spaced. Measurements on the flow of a 20% by volume oil in water mixture showed tha t the flow of this two phase mixture was similarly improved by the presence of a perforated baffle. (C) 2000 Elsevier Science S.A. All rights reserved .