Home »
Home » Sugar Cane
June 26, 2000
Sugar cane refineries have been on our list of markets to explore for the last six years. They were added to the list because in the 1950’s into the 1970’s Vincent dryers and a screw press were sold for use in Florida and Mexican sugar cane processing plants. During the recent harvest season a Fiber Filter study was conducted.
We found that generally the sugar cane arrives at the refinery already cut into short 6″ pieces. These are shredded in giant hammermills of huge torque and horsepower ratings. These break open about 90% of the plant cells.
The shredded material is run through a series of roller drum mills. A casual look at these presses showed that it was no place to put a screw press. Typically there were a row of six sets of three-roll presses operating at only 4 rpm. These are each driven by 600 to 1,500 horsepower steam turbines. The drive shafts are 20″ in diameter because of extremely high torque.
The crusher rolls are about 3′ in diameter, stacked in a pyramid. They are made with meshing grooves that are about 3″ deep. Because of the severe abrasive condition, they are repeatedly, almost continuously, hardsurfaced with weld applied material.
The cake from the final set of presses has around 50% moisture. It is used as boiler fuel to generate the steam required for the stream turbine drives and to operate the juice evaporators.
We saw a French Oil Mill screw press that had been tested and heard of others. Their fate was all the same: the abrasion all but destroyed the machines in a single operating season.
We hoped that the Fiber Filter might be useful in filtering the fiber from the sugar cane juice (press liquor). The flows are huge, generally 1,000 to 2,000 gpm. A Model FF-6 was supplied for joint testing between Louisiana State University and Evan Hall Sugar Coop. The machine could not be justified. Filtering the fiber from the juice ahead of the conventional decanter removed a press aid effect that was necessary for proper clarifier operation. At the same time, the fiber particles left in the juice after the clarifier were too small for capture by the Fiber Filter.
The price of sugar is currently at a fifteen year low. February 2001 update: Most of the mills we visited are now closed or in bankruptcy.
Issue 107