High energy loss fluid flow control device

Abstract

A high energy loss fluid flow control device suitable for use with high temperature, abrasive coal liquids, gases and the like comprises an elongated body having an axially extending bore with longitudinally spaced apart inlet and outlet passages in communication with the bore. An elongated valve member is mounted for sliding axial movement within the bore between open and closed positions. The valve member includes an outer surface spiralling about a longitudinal axis from a maximum diameter portion adjacent one passage toward a minimum diameter portion adjacent the other passage. The bore of the elongated body includes a surface in close facing relation with the spiralling surface of the valve member and this surface also is spiralled about a longitudinal axis from a minimum diameter portion towards a maximum diameter portion. The cooperative spiralling surfaces of the bore and valve member define a spiral fluid flow path extending between the inlet and outlet passages having a generally polygonal, transverse cross-section which may be of constant or continuously increasing cross-sectional area between the inlet and outlet passages. Means is provided for moving the valve member longitudinally in the bore between open and closed positions. The flow control device has a unique step-tapered design providing for minimal clearance flow and fewer crevices or dead space wherein solid materials (commonly found in coal liquids and gases) can collect and interfere with operation.