Preventing unscheduled shutdowns at paper mill

Cross automatic filters are installed at a large paperboard mill in the UK to permanently protect against the risk of expensive pump failures and plant shutdowns due to poor quality lubricating water

Cross automatic filters have been installed at one of the largest paperboard mills in the UK to permanently protect against the risk of expensive pump failures and plant shutdowns due to poor quality lubricating water.

The mill has recently been modernised and expanded, introducing state-of-the-art plant and machinery, including new pulpmill pumps that use water to lubricate their mechanical seals and glands.

The pumps are protected against a contaminated water supply by flow switches, which automatically shut down the plant if they begin to register a blockage.

It soon became apparent that this plant demanded a higher quality of water than could be guaranteed from the mill's river water source.

Although the mill has always treated the incoming water supply, this was found to be insufficient to prevent the pulpmill from shutting down as a result of blockages, which had a knock-on effect on the operation of the rest of the mill.

If the pulpmill has an unscheduled shutdown because of the seal water, it could result in blockages that might take several hours and cost many thousands of pounds if the board machines have to shut.

It is also vital that the mechanical pumps always have water to lubricate the seals, since just 60 seconds without it can ruin them.

Filtration specialists John Morfield were invited to find a solution to this expensive and disruptive problem.

They recommended the installation of Cross automatic filtration equipment, which would permanently remove the offending contamination without interrupting the water supply.

Cross filters utilise specially designed 'zero-gravity' filter coils which use a pressure differential or time lapse signal to backwash to a completely clean condition.

Cross 'Phoenix' filter units each comprise six coils, which are individually and sequentially backwashed, with no interruption to the flow through the filter.

Three Phoenix filters, rated at 50 microns, have been installed to protect the pulpmill, providing the additional ability to continue plant operation if one is taken off line.

Another, 25 micron rated 'Phoenix' filter is also installed on the dedicated lubrication line for the mill refiner plant.

The introduction of the Cross filters has swiftly benefited the operation of the mill.

Their success in avoiding unscheduled shutdowns in the pulpmill has recouped the GBP20,000 cost of fitting them in only a few months.

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