Pannevis GT gas tight filters from Larox are the proven technology for filtering carboxy methyl cellulose.

LAPPEENRANTA, FINLAND - March 10, 2008 - With over 20 successful working
installations worldwide and more currently under construction, the Pannevis GT
gas-tight filter from Larox is now the accepted way to process carboxy
methyl-cellulose. 

The production of carboxy methyl cellulose (CMC) involves an alkali hydrolysis
of a cellulosic feedstock followed by carboxylation. This causes the formation
of sodium chloride which has to be washed out of the CMC before it can be
further processed. Unfortunately this is not so simple, as CMC is soluble in
water, so it has to be washed with an alcohol/water mixture usually with a
minimum of 60% alcohol. There are three main grades of CMC, technical or crude
CMC, purified and food grade. Food grade requires better than 99.8% pure CMC. 

Multiple wash stages are required in a counter-current sequence to achieve the
varying purity levels. The wash ratios utilized together with the high alcohol
content, to stabilize the CMC in the presence of water, require counter current
washing to keep the process economically feasible. Traditionally the CMC
production was ran on series of up to 6 centrifuges, set up in counter-current
mode but over the last 20 years the Pannevis GT filter has become the equipment
of choice as it is possible to carry out from 3 up to 8 or more counter-current
wash steps in a single unit under a sealed, re-circulatory nitrogen atmosphere.
Pannevis GT filters easily achieve the purity requirements of all three grades,
including the food grade. 

The Pannevis GT filter offers all the advantages of the standard Pannevis RT
filter including the capability to carry out multiple step counter-current
washing. 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 the gas exiting with the filter cake. 

Large windows in the sidewalls and lights on the roof ensure complete
visibility of the process inside the housing. The housing is designed to
ensuring all internal surfaces are easily cleaned and self draining.
Clean-in-place (CIP) is a standard option and the basic design is suitable for
sanitary processes as all dead spots are eliminated, windows and nozzles are
sloped to drain back into the housing and internal surfaces can easily be
polished to any specified level. 

As with all of the Pannevis RT based filters, the GT filter is extremely
reliable and maintenance is simple. All the major service items including the
cloth drive, bearings, pneumatic cylinders and sensors are mounted outside the
housing, eliminating both the risk of product contamination and the need to
access inside the filter housing for normal scheduled maintenance. Thus the
inert integrity of the filter is maintained at all times. 

Continuous filter cloth cleaning eliminates cross contamination and guarantees
100% product recovery. Cloth wash liquid can be recycled over the filter cake
assuring total solids capture and minimizing the consumption of fresh liquid.
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. 

Larox is committed to helping its clients meet the following goals
- Reduced lifetime production costs - especially energy based costs
- Improved product quality, value and consistency
- Improved safety, health and environmental performance
- Improved yield and productivity

The Pannevis range of horizontal vacuum belt filters is fully supported by the
Larox Service group, the most comprehensive and experienced network in the
industry, covering the world with operations in over 40 countries and providing
reliable support throughout the entire lifecycle of the product - “Performance
for Life”. 

For more information please contact:

Larox Corporation
P.O. Box 29
53101, Lappeenranta, Finland
Phone +358 207 687 200
Fax +358 207 687 277
E-mail info@larox.com
Internet www.larox.com