Larox Corporation

May 16, 2007
Gas-tight, horizontal belt filter introduced for edible oil application

Larox recently delivered the largest, totally gas tight horizontal belt filter ever built. The Pannevis GT filter, with a filtration area of 3 m wide x 16.8 m long (50.4 m2 total filtration area) was recently delivered for a solvent based edible oil application. Operating under a nitrogen atmosphere, the Pannevis GT filter offers total containment of solvent based processes in an inert environment for safe and hygienic processing of a wide range of products including fine chemicals, bio-products, solvent-processed foodstuffs, solvent wetted organic solids, pyrophoric materials and pharmaceuticals. Larox is the world leader in solvent-based vacuum belt filtration with the Pannevis GT filter.

The filter as delivered is designed to work at temperatures below ambient and is equipped with 3x counter-current washing with the washes applied by banks of spray nozzles for maximum cake coverage during each wash stage. Washing of the filter cloth sides prior to discharge also ensures all possible solid phase product is recovered. Both the solid and liquid phases are further processed as valuable product in this application.

The Pannevis GT filter offers all the advantages of the standard Pannevis RT filter including capability to carry out co- or counter-current washing, reflux washing, vibration, all forms of mechanical compression and either hot gas or micro-wave drying. They can be configured in any combination of the above options for multi-step processing exactly as the standard RT filters.

The filter housing is normally operated with a slight internal over-pressure using nitrogen, which is continuously re-circulated around the filter circuit so that all components including filtrate receivers and pumps are totally inert. A very small make-up of nitrogen is required to compensate for nitrogen exiting with the filter cake.

Large windows in the sidewalls and lights in the roof ensure complete visibility. The windows also provide local access within the housing. The floor and roof of the housing are rounded while the sidewalls are flat so ensuring that all internal surfaces are easily cleaned and self draining. Clean-in-place (CIP) is a standard option and the filter is designed for sanitary processes as all dead spots are eliminated, windows and nozzles are angled to drain back into the housing and internal surfaces can easily be polished to a specified level.

Continuous filter cloth cleaning eliminates cross contamination and guarantees 100% product recovery, as cloth wash liquid can be recycled over the filter cake for total solids capture. Batch identification, when required, is easily achieved by carrying out semi-continuous operation. Full validation procedures to meet all FDA final product requirements are proven and available. When operating with solvent, the filters meet all the requirements of ATEX 95 category 2.