Nov 01 Update
Over the years Vincent has had many inquiries in regards to using a screw press with a coffee waste product.
The Vincent press is well suited for dewatering waste streams in the coffee processing industry. This is most commonly done with chaff and with spent grounds in soluble coffee (instant and decaf) operations. The objective is to remove the excess water so as to produce a press cake suitable either for incineration or landfill.
One local coffee bean processor has a Jones vertical press in daily use on chaff off the bean. The press cake goes to a fertilizer company that uses it as a filler.
A large coffee bean processor in Texas is getting 50% to 55% moisture content in the press cake with either a Davenport or a Rietz V-press. These robust machines come in two sizes: 3' and 5'. They consist of two rotating cones with perforated screen on the faces of the cones. The shafts are mounted at an angle to each other so that there is a large gap on one side and a small gap on the other. Material is fed into the large gap and as the cones rotate the material is compressed by brute force until it is allowed to fall out at the small gap: The pressing is very gentle as there is absolutely no agitation. These machines are expensive because of their heavy construction, and they are of low capacity as compared to screw presses. Their maintenance cost is regarded as excessive by most users we have talked to.
These Davenport presses will handle from 4,000 to 10,000 pounds per hour of inbound material. Their press cake will consistently be in the range of 50% to 55% moisture, which makes the press cake suitable for incineration. Some Folgers and Maxwell plants were originally set up for incineration, but most seem to have abandoned the practice or been shut down over the years.
In 1986 Vincent ran tests for Westreco (Nestles) with inbound material that contained 70% to 74% moisture. This was for a waste disposal project involving canned iced tea and a coffee drink. Moisture contents in the press cake of 58% to 63% were achieved with our press. This was regarded as good as was being achieved elsewhere with vertical presses with the same material, but no better. Thus they could not justify buying our press even though they liked its performance.
Recently we received an order for a CP-10 that will be used to dewater coffee grounds for a venture with Starbucks coffee. The press will reduce the moisture content of the grounds to the point where they can be conveyed in a pneumatic vacuum system.
There is another interesting application of Vincent equipment in the coffee industry. It has to do with one of the first steps in the production of coffee, near the site where it is grown. Coffee growers must dispose of the red pulp that they remove form the coffee bean. This pulp can be converted into a material to be blended with animal feedstuffs. This is achieved by first pressing and then further drying the material.
November 2001 Addendum: Vincent has been selling about one Series CP press per year for dewatering spent coffee.