Control and pump system makes the most of whisky distillation

Paul Boughton

Glenfiddich was founded in 1886 by William Grant and on Christmas day 1887 the first Glenfiddich spirit trickled from the stills.

Today Glenfiddich is the best-selling single malt Scotch whisky in the world: one in every five bottles of single malt whisky sold in the world is a bottle of Glenfiddich (Fig.1).
In the distillation process, the wash that is created from the fermentation of the malted barley is distilled in copper pots that exactly match the shape and size of the original stills bought over a century ago by William Grant.
Continual heating gradually turns the alcohol to vapour, which rises through the narrowing neck of the still and is guided downwards through a water-cooled condenser.
At this stage the condensate contains about 21percent alcohol, and the distillation process is repeated in smaller aspirit stills'. The vapourised alcohol is drawn off and condensed as before, with the final liquid now legally a bonded, taxable spirit.
Running and monitoring the distillation process is the responsibility of a stillman, and is a delicate operation where any mistake can ruin the whisky's flavour. Only the fine middle cut, or heart of the distillation is retained for maturation, which the stillman catches at the flick of a tap.

Crucial to the process, then, is the cooling of the condensate. The water for the cooling operation comes from a storage dam, which is in turn kept topped up by pumping from a nearby pond formed from the Glenfiddich river (Fig.2).
We use two pumps to push the water up against gravity to the storage damensuring we have a reliable water supply for the condensation process says Glenfiddich's Derek Matheson. Historically we had run the pumps at fixed speed24hours a dayseven days a week365 days a yearbut we began to wonder if we could increase efficiency without compromising supply."
Looking around for systems that would provide this efficiency boostGlenfiddich highlighted an innovative ultrasonic level measurement and water distribution system from Siemens Process Instruments (which consolidates the instrumentation product offerings previously supplied through Milltronics) -- the EnviroRanger ERS500. Using non-contacting ultrasonic technology and patented echo processing techiquesthe EnviroRanger accurately monitors and control liquid levelsproviding control outputs to variable speed drives for more efficient pump operationand eliminating the need for any further discrete control equipment.
When Matheson asked about suitable variable speed drives for the pumps to work in conjunction with the EnviroRangerMicroMaster drives were recommended.
Two Siemens MicroMaster inverters were duly installedlinked via Profibus to the EnviroRangerwhich provides the required control signals based on the water level in the storage dam.
A key advantage of the system is that the pumps no longer need to be driven at fixed speed. Since the power used by a pump is proportional to the cube of speeda nominal reduction in speed can give a much larger percentage reduction in energy.
There are secondary benefitsas well. Because the MicroMaster drives ramp-up the pumps to the required speedand then ramp them back down at programmed rates for starting and stoppingthe motors are not hit by the huge initial torque that comes with direct-on-line startingso reducing maintenance and lengthening the operating lifespan.
"With the new control system in placewe are accurately controlling the pumps so that water delivery precisely matches demand added Matheson. That means we are making significant energy savings. Andbecause the package was highly cost-effectivewe have quickly translated those energy savings into a genuine cost reduction."

Scottish Highlands DistilleryGlenfiddich has used Siemens variable speed drives on their water control and pumping system.


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