Screw compressor and outlet portion for screw compressor

Abstract

The invention relates to a conical screw press for compressing and for removing liquid from bulk material, comprising a screw with a screw thread and a core in a housing, structure for rotating the screw in the housing, an inlet opening for the bulk material from which liquid is to be removed, an outlet opening for the bulk material from which liquid has been removed, and at least one outlet opening for the liquid which has been extracted. The characteristic features of the invention are that: a) the screw is dimensioned, for at least the greater portion of the length of the screw between the inlet opening for bulk material and the outlet opening for bulk material, such that the external diameter (D) of the screw thread and the diameter (d) of the screw core change axially in the screw press from a first axial position, where the external diameter of the screw thread=D.sub.1 and the diameter of the screw core=d.sub.1, to a second axial position, situated downstream in the direction of the bulk material, where the external diameter of the screw thread=D.sub.2 and the diameter of the screw core=d.sub.2, in accordance with the formula: ##EQU1## where K is a compression ratio describing the volume of the bulk material at the first position in relation to the volume of the bulk material at the second position, and n is a number between 2.5 and 3.5; and b) the angle .alpha. of the screw threads in relation to a plane at right angles to the screw shank varies by at most 20% in either direction from a constant angle in relation to the plane within the portion of the length of the screw.

Dependencies are inferred from the claim text.