Patent GB-947990-A (GB)
Title: Process and apparatus for separating components of a liquid-solids mixture
IPC: B04B1/12
Filed: 1962-10-08
Abstract: 947,990. Centrifugal separators. SHARPLES CORPORATION. Oct. 8, 1962 [Oct. 19, 1961], No. 37948/62. Heading B2P. [Also in Division C5] The components of a liquid-solids mixture in which the solids have a tendency to retain portions of the liquid are separated from each other by introducing the mixture and a carrier liquid heavier than, and immiscible with, the liquid of the mixture into a zone of centrifugation where the carrier liquid displaces the mixture inwardly and the solids form a concentrate layer immediately inward of the carrier liquid, causing a rapid shallow localized flow of the carrier liquid immediately radially outward of the concentrate layer in a direction substantially tangentially to it and an outward spilling of the carrier liquid adjacent the flow to agitate the adjacent solids in the concentrate layer causing them to release a portion of their retained liquid, and permitting a discharge separately of the liquid component and of the carrier liquid, the latter including entrained solids from the concentrate layer. The process may be applied to the dewaxing of oil. A mixture of solidified wax and oil, which may be dissolved in a solvent, is fed to the separating zone of a centrifuge bowl, Figs. 1 and 2, provided with frusto-conical discs 28 through tubes 40, 24 and distribution holes 27, 29. The carrier liquid, such as brine or water, from a pipe 70 passes through ducts 48 and tubes 50 to discharge within the bowl adjacent nozzles 52 for the discharge of the wax solids and the carrier liquid. Each nozzle has a discharge opening 62 facing rearwardly of the direction of rotation of the bowl and is provided with a tube extension 66. During operation, a carrier liquid-wax interface is formed at a and a wax-oil interface at b. The shallow localized flow of the carrier liquid in discharging through the tube extension 66 creates a Venturi effect promoting the entrainment of the wax solids from the interface a. The separated oil is discharged upwards through a passage 30 and over a ring dam 34 into the cover 38 of the apparatus. Separation of the wax may be facilitated by the addition of surface active agents of the ionic type such as organo-phosphorus compounds, e.g. sodium di-decyl phosphate. In a modified form of the centrifuge, Fig. 3, a dividing cone 72 is disposed above the upper disc element and spaced from the top 18<SP>1</SP> of the bowl defining a passage 74 for the discharge of excess carrier liquid. The upper end of the dividing cone has an extension 76 terminating in a discharge weir 78 for the separated oil. In a modification of Fig. 3, the passages 48<SP>1</SP> and the tubes 50<SP>1</SP> are eliminated and the carrier liquid is fed either through the tube 24<SP>1</SP> with the oil-wax mixture or through the passage 74. In a further modification, the nozzles 52<SP>1</SP> are replaced by an inwardly projecting annular dam integral with. or secured to, the wall of the bowl between the lower end of the cone 72 and the upper end of the tube 50<SP>1</SP>. The carrier liquid flows over the annular dam and, entraining the wax solids, is discharged through the passage 74. The process may also be applied to the production of tall oil to asisst in the removal of liquid between the oil layer and the mineral acid layer or to the separation of sterols from acidulated vegetable oil soap stocks.