Process and apparatus for contacting a liquid with a gas

XII In a process for deodorising an oil with steam, the steam is injected upwardly into the lower portion of a horizontal stream of the oil along a length of the stream to cause the mixture of oil and steam in a longitudinal zone of the stream to rise to a position in which it moves to a second longitudinal zone of the stream spaced transversely from the other longitudinal zone and wherein the oil descends and returns to the first longitudinal zone so that the oil follows a helical path in the direction of flow of the stream. The pro cess may be carried out under vacuum and the steam may be injected at a plurality of points at a pressure not less than twice the static pressure at the point of injection. The ratio of the speed of local circulation to the speed of longitudinal movement of the stream of oil is preferably not less than 100:1 and may be 1000:1. In the apparatus shown, the oil is passed through a series of concentric circular channels arranged on a tray with a central opening and connected so that the oil flows from the innermost channel to the outer most channel. A number of such trays are arranged one above the other in a vertical column and oil from an outermost channel flows to the innermost channel of the next lower tray through a pipe 38. Steam is fed into each channel from a pipe 28 and a hood is provided over the partitions which divide each channel into two transversely spaced zones. The steam containing the odorous sub stances passes to a central duct 39 from which it is removed by an evacuating arrangement (not shown). As shown in Fig. 7 a plate 21 cuts across all the channels and oil flow be tween the channels is by way of gaps 23 and 24 in the walls of the channel.