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From self-cleaning filters to automatic-discharge centrifuges
Solid-liquid separation is a key unit operation that processors look to for a wide-range of applications ranging from: the lowly removal of debris from coolingfluid lines and products; through the recovery of product from solvents; to massive-scale dewatering of sludge and mineral slurries. Depending on the application, there is a plethora of technology available to perform these tasks. What follows is a brief overview of new developments in filtration and centrifuge technology.
Self-cleaning filters
Early this year, Russell Finex, Inc. (Pineville, N.C.) added another model to its Eco Self Cleaning Filters, the 502 Eco Filter. Similar to other filters in the Eco range, the 502 can be specified with a straight wiper or a SpiroKlene wiper, which continuously wipes the inside of the filter element and positively moves oversize material into the sump section with a corkscrew action. With this design, the movement of oversize material does not rely on gravity, so the filter can be mounted horizontally as well as vertically.
The reusable filter elements are continuously cleaned, and therefore the need for stripdown is infrequent, says the firm; the stainless steel microscreen can be cleaned rather than thrown away as landfill, as in the case for disposable bag. "Substantial" savings in operating costs are said to be achieved, compared to disposable bag and cartridges, which incur high costs for media replacement and disposal, product loss and downtime, says the firm.
A range of Eco Filters are available handling throughputs from a few hundred liters per hour up to rates over 100,000 L/h. Pressure buildup is thus kept at a minimum, oven for filtration cutoff levels down to 10 micron. Jacketed options are available for filtering products, such as chocolate, that need to be kept above ambient temperature.
The TRF (photo) from GTI FIB Industriële Bedrijven B.V., Leeuwarden, Netherlands) is a dynamic cross-flow membrane system that features a patented rotating membrane filter for nano and microfiltration applications. The rotating membrane is continuously cleaned by a turbulent liquidstream flowing with a velocity of 5 m/s. The TRF can be used for filtering fat in wastewater, achieving a 98% reduction of fat to meet Dutch standards of less than 300 ppm. At the same time, the chemical oxygen demand...