Earlier this month testing was begun with a new high performance screw. This screw was designed to maximize pressing performance. Along with new resistor bars, it was retrofited to a VP-22 dewatering screw press at the Cargill citrus plant in Frostproof, Florida.

The press in question was originally built in 1978 for pressing alfalfa. It had a 100 hp DC drive at a time when 40 hp was standard on the VP-22. In 1992 it was acquired by Proctor & Gamble who then owned the Frostproof plant. They had Vincent convert the press to pressing orange peel with a 75 hp motor and gear reducer.

Initial results were below expectations. The horsepower drawn was under 40, and press cake moisture was over 68%. A Supercharger was added in 1993, and horsepower went up to 50 while press cake moisture came down to 65%.

With the latest modification the power drawn has increased to 60 hp, and press cake moisture is averaging under 63%! Changes made to the screw include a tighter pitch, a different contour, and angular changes. To increase press throughput capacity, (1) the gearing of the variable speed Supercharger drive was increased by a third, and (2) the screw shaft diameter in the inlet hopper was decreased. An 11% increase in press capacity should result from this latter change alone. In addition a change was made to a reactor bar feature that had gone unaltered since the early 1950’s.

The benefits of the high performance screw design are being made available throughout the Vincent product line. For example, the new screw design has already been offered to a brewery in Taiwan for a VP-10 pressing spent rice wine grain.

April 1997 addendum: The extremely high compression design can result in enough back-pressure to reduce press throughput capacity. For this reason our standard today falls between the original and the Cargill designs.