Screw press with continuous slope feed screw

A predrainer screw press for extracting free run and other juice from destemmed grape must by pressing and by centrifugal force, said press having an inlet end, a hopper for feeding must into the inlet end, and an outlet end, comprising:

• a cylindrical cage formed from at least one pair of semi-cylindrical frames, said frames supporting filter screens serving to pass extracted juice from said must therethrough, said pair of semi-cylindrical frames attached to offset hinges along the lower edges thereof and removeably attached along the upper edges thereof, whereby said cylindrical cage may be opened for cleaning of said screens or replacement of said screens;
• a rotatable feed screw having a body with a sloping frusto-conical shape, and a screw thread disposed helically around the surface of said body, the outside diameter of said screw thread having a ratio to the pitch of said frusto-conical shape not exceeding two-to-one, said feed screw disposed concentrically in said cylindrical cage and said screw thread having an outside diameter essentially equal to the inside diameter of said cage, the slope of said body selected to provide a gradual reduction in volume of the flights of said screw thread from the inlet end to the outlet end of said screw press to gently and progressively squeeze said must against said filter screens as said must is fed by a head of said must in said hopper from said inlet end to said outlet end of said press by rotation of said feed screw;
• adjustable drive means attached to said feed screw for rotating said feed screw at a rate which will produce sufficient centrifugal force on the juice in said must to maximize the amount of extracted juice from said must for a selected throughput of said must.

A dewatering system for liquid-containing materials comprising:

• (1) At least one predrainer screw press having
• (a) a cylindrical cage having an input for materials and having filter screen walls,
• (b) a rotatable feed screw having a body with a sloping frusto-conical shape and a screw thread disposed helically around the surface of said body, the ratio between the diameter of said screw thread to the pitch of said body being 2 to 1 or less,
• (c) adjustable drive means for rotating said feed screw at a rate sufficient to produce sufficient centrifugal force on the liquid in the material being dewatered to extract a portion of said liquid by such centrifugal force,
• (d) a drain outlet associated with said cage for receiving liquid extracted from the material, and
• (e) a pulp outlet for expression of material after extraction of liquid,
• (2) Separator means connected to said drain for receiving extracted liquid and separating remaining solid matter therein from the liquid;
• and
• (3) Conveyor means associated with said separator means for transporting the separated solid matter from said separator and feeding the same into said input.