Patent ID: 7476317

Claim:
A hydrocyclone for effecting separation of a combined phase input stream with at least two constituents comprising: inner and outer spaced shells which are concentric with a longitudinal axis and each of which has an inner surface and an outer surface, the outer shell having an inner surface radius with respect to said longitudinal axis which is greater than the radius of the outer surface of the inner shell with respect to said axis to form therebetween a cyclone chamber providing a helical path for the stream, the shells having an input opening therebetween at one end of the cyclone chamber for receiving the stream and an output opening therebetween at the opposite end of the cyclone chamber for discharging separated constituents of the stream; wherein the inner surface of the inner shell is spaced from the longitudinal axis and defines an inner shell bore which has one end at and which extends from the chamber output opening to adjacent the chamber input opening for conveying a separated constituent to an end of the bore adjacent the chamber input opening; at least one wall forming an expansion chamber which is within a circle lying in a plane perpendicular to and centered on the longitudinal axis and having a radius not more than 30% greater than the radius of the outer surface of the outer shell, said expansion chamber having a first opening which opens to the input opening of the cyclone chamber and a second opening spaced from the first opening for providing the input stream to the expansion chamber, the spacing of the first opening and the second opening and the dimensions of the expansion chamber being selected to substantially reduce the velocity of the input stream, at least by the time that the stream reaches the input opening of the cyclone chamber, with respect to the velocity of the input stream at the second opening of the expansion chamber; and a tubular extension of the inner shell extending from the end of the bore of the inner shell adjacent the input opening of the cyclone chamber to exteriorly of the expansion chamber.