Spray Chamber Dust
Everyone is familiar with Formica counter tops. This material is made from ground wood dust that is combined with phenolic resin. The material is heated and pressed to produce a rigid, homogeneous, void-free material. In addition to counter tops, the material is used for wall paneling (Masonite board) and furniture. Vincent Corporation buys rods and tubes of this material, called Ryertex, to manufacture certain bushings and screw conveyor hanger bearings.
The International Paper plant in Hampton, South Carolina produces Micarta sheets and rods of this material. It is known for its electrical insulating properties. One of their engineers happened upon the Vincent web site, www.vincentcorp.com, and thought of using a screw press to dewater their waste stream. A phone call was made and, within a very few months, a Model CP-12 screw press was built and installed.
Sawing and sanding operations are part of the manufacturing process, which creates a lot of dust. Dust-laden exhaust air is drawn through the chamber, and water is sprayed into the air. The dust and water fall to the bottom of the chamber, forming a sludge. There was a need to separate the free water because the waste is sent to landfill.
To dewater the sludge from the spray chamber it is elevated by a drag flight conveyor to the CP-12. This flow is about 1,000 pph at 16% consistency. The press cake produced by the press is a dry material with only 32% moisture, and the press liquor is clear enough for reuse within the plant.
Initially the CP-12 did not perform very well. Then the screw was slowed by switching to a 1200 rpm motor. With this change the cake became much drier.
An unexpected problem was encountered at the installation. The powdery press cake entered between the screw shaft and the cone bushing. The heat was sufficient to melt resin that is present, and the cone started seizing to the screw shaft. The condition was caught before serious damage occurred.
To address the situation an automatic lube system was designed and supplied. It uses compressed air to pump lubricating grease to the cone bushing. A timer sets the frequency and duration of the pump cycle. This system is now being offered as standard in a variety of Vincent applications.