ENERGY SAVING – WATER IS
THE KEY
Poor attention to
water management can lose millions of dollars literally down the
drain each year from losses in fibre, power, chemicals and energy
in the form of heat, by using cold fresh water in the plant rather
than re-using warm clarified water.
Because of the need to produce a quality of recycled water that
is safe for reuse, better methods of treatment are being sought
and used. The Microfilter is one of those concepts.
After a survey of their water system and some trials. Hunsfos Paper
Mill, part of the Swiss owned Cham Group decided to install Microfilters
each of their machines, replacing the existing DAF units. Their
main objective was to produce a quality of water in order to be
able to re-use water and increase the machine system temperatures
overall, at the same time saving water, fibre and reducing effluent
discharge
In short, after commissioning, the mill set about re-routing the
flow of clear filtrate from the Microfilters to replace fresh water.
Some application areas were: wire & high pressure showers;
sealing water on mechanical seals and pump stuffing boxes; sealing
water on vacuum pumps; replacing fresh wash up water by re-cycled
water.
Two filters were installed on each of the smaller machines and
the third and largest unit on the biggest machine.
The result was a 5% reduction in electricity use, with 20% saving
in the yankee hood and 14% in the drying cylinders. The temperature
of the water discharged to the effluent plant increased from the
previous 13 up to 23 . Water consumption was reduced by 47% and
the amount of solids in the waste water passing to the effluent
system was reduced by 67%. Payback time was three months.
A recently developed computer programme can calculate from the
input of information from the customer mill, the savings that are
possible to achieve.
Details of water flow, solids content and stock preparation power
in kWh/ton, water and energy costs etc can be collated and those
in individual areas or for total savings can be presented.
Based on a raw material cost of $300/ton and adding associated
savings of water, power, energy, chemicals and sludge disposal
costs, saved by better water management, total savings of plus
$1.7 million/yr can be achieved.
For more information, contact Len W Dewhurst, Director of Sales,
ALGAS Fluid Technology Systems, P.O. Box 534, NO-1503 Moss, Norway
