Patent ID: 6521120
Filing Date: 2003-02-18
Classification: B04B

Abstract:
A continuous centrifuge comprising a perforated basket of generally frusto-conical configuration which is adapted to rotate about a rotational axis and along whose inner peripheral wall a liquids/solids mix is caused to travel, with solids being discharged over a mouth of the rotating basket at its wider end and liquids being collected through perforations defined in the basket, wherein the basket has at least three regions of different inclination relative to the rotational axis of the basket corresponding respectively to (i) a liquid stage at the end of the basket wherein during rotation, solids in a liquids/solids mix are largely suspended as individual particles in a liquid volume, with liquid viscosity and inclination of the liquid stage being principally responsible for controlling the flow rate of the mix along the inclined basket wall, (ii) an intermediate stage wherein during rotation, the solids are immersed in a reduced liquid volume such that contact with each other and with the basket wall is increased, with a resulting apparent increase in liquid viscosity, frictional contact between some of the solids and the basket wall, and local basket inclination being principally responsible for controlling the flow rate of the mixture along the inclined basket wall, and (iii) a solids stage wherein during rotation, surplus liquid having been substantially removed via the basket perforations, solids are largely in contact with each other and the screen, with the coefficient of friction between the solids and the basket wall, between solid particles themselves and local basket inclination being principally responsible for controlling the flow rate of separated solids, the local basket inclination of each stage being set to control the flow rate and residence time over each stage individually and wherein, in addition, there is a reduction in the basket inclination between the solids stage and the mouth of the basket.