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Water of Life
Siemens energy technology is helping a Scottish distiller to make uisge beatha, the water
of life, one of the world’s oldest alcoholic beverages known as whisky. A new environmentally friendly CHP energy center not only provides the distillery with high-reliability process
steam and all its electrical power, but also exports surplus electricity to the local grid.
Despite the faint but distinct odor of whisky in the air, the distillery
operated by family-owned Scotch whisky distillers William Grant &
Sons at Girvan bears little resemblance to the layperson’s perception of traditional whisky making. Set on a large industrial site
near the small town of Girvan on the Ayrshire coast, not far from
Scotland’s famous golf courses at Royal Troon and Turnberry, the
distillery has stunning views of hills, sea and in the distance the
craggy offshore island of Ailsa Craig. Nevertheless, with its giant
steel silos, complex vessels, tanks and maze of gleaming pipe
work, the facility could be easily mistaken for almost any industrial
processing unit.
THE IRISH CONNECTION
VIVE LA DIFFÉRENCE
WHEAT, WORT, WASH AND WHISKY
The principal difference between Grant’s Girvan operation and its
other distilleries is that the Ayrshire plant is dedicated principally
to the production of grain whisky, rather than the highly-prized
single malts such as the Balvenie and the company’s world-leading
Glenfiddich. These famous brands are made in traditional ‘pot’
stills at the ‘single’ distilleries in the Scottish highlands giving the
brand-name location, using a fixed quantity of fermented malted
barley and distilled as many as three times.
In the continuous production of grain whisky at Grant’s Girvan distillery, a mixture of milled wheat and malted barley is cooked in
water at high temperature to form the wort, a dark-colored sugary
liquid. This is cooled and transferred to fermentation vessels
called washbacks, where yeast is added to produce a viscous, beerlike liquid from the soluble sugar, with an alcohol content of
between 8 and 9 per cent. The fermented liquid, known as wash, is
pumped to the top of the first column or ‘analyzer’ of the double-
Alternatively, grain whisky is made from a fermented ‘wash’ based
mainly on finely ground wheat. Raw spirit is produced in a continuous operation on an industrial scale in very large distillation units
based on the ‘patent’ or ‘Coffey’ still — a form of double-column
heat exchanger developed in 1831 by Irishman Aeneas Coffey — to
produce large volumes of high-quality neutral grain alcohol,
efficiently and economically. This in turn can be used either as the
principal constituent of other spirits such as gin or vodka, or it
can be matured in oak barrels for a minimum of three years to create the light whisky which forms the base for all blended whiskies.
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column distillation unit, and high temperature steam is fed into the
base. The steam rises to meet the cooled wash causing alcohol to
boil off as vapor. This is fed to the base of the second, ‘rectifier’ column where it rises, cools, condenses and is run off through
further cooling stages and collected continuously as 94 per cent
by volume, neutral grain alcohol.
After maturing in oak barrels for three years to convert the neutral
grain alcohol into whisky, the resulting light and fragrant product
is blended with up to 30 malt whiskies and left for several months
to ‘marry’ in large oak vessels called tuns. This creates the distinctive
flavors and aromas of Grant’s own blended brand, which is finally
bottled at its plant at Motherwell near Glasgow. As well as forming the
base for its own blended whisky, the mature grain whisky is also
supplied in bulk to virtually all other Scotch whisky-makers as a base
for the blended brands marketed by these companies.
INNOVATIVE ENERGY
Founded in 1886 by William Grant and now operated by his descendents, the company is the largest of the handful of Scotch
whisky distillers remaining in family ownership and the world’s
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fourth largest producer of Scotch whisky. The company has a history of innovation, being the very first to pioneer single malt
whisky and more recently with the introduction of the solera concept, to create Glenfiddich Solera Reserve. Innovation has also
extended to the company’s manufacturing technologies, with significant recent investments in leading-edge process-monitoring
and control systems from Siemens. However, one of the largest and
most important investments in new technology in recent years
has been the installation by Siemens Industrial Turbomachinery of
a combined heat and power (CHP) plant, which now forms the heart
of a new Energy Center at the whisky distiller’s Girvan operation.
Prior to the CHP installation, the high energy demand for both
process steam and electrical power at the distillery was supplied respectively by large boilers burning heavy fuel oil and by the
local electrical power utility and formed a major and rapidly-increasing percentage of the company’s total production costs. In 2001,
mains gas supplies became available for the first time at the plant
and the decision was taken by Grants to replace the existing boilers with modern gas-fired units and to generate their own electricity and additional steam, using a modern, clean and energy-efficient combined heat and power system.
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“We went through a very steep learningcurve to become an independent power
producer, but we have been helped at
every step by the people at Siemens and
the company has proved to be an excellent partner.”
THE RIGHT CHOICE
“It was a very difficult decision for us,” explained Distillery Manager
Conn Lynch. “We had to be persuaded that moving away from
our core business to generate our own power would be the right way
forward. We looked carefully at our requirements, visited quite
a number of CHP installations in Scotland to see just how they were
operated and talked to a number of possible suppliers including
both Centrax and Turbomach as well as Siemens,” said Lynch. “Our
final choice was for a package from Siemens, based on the SGT-100
gas turbine, a gas compressor and heat recovery steam generator. With a rating of 5.25 megawatts and capable of supplying
process steam at the rate of around 11 tonnes per hour, this
met precisely our requirements for both heat and electrical power.”
WATCHING BRIEF
The outcome was a very satisfactory one, not least for Lincoln-based
Alastair Stirrat, Siemens’ Gas Turbine Product Strategy Manager,
who had been at the center of discussions with the customer. “We
formed a very good relationship with Grant’s and I’m sure that
they feel that we have done a good job for them,” he commented.
“At the same time, we have been keeping a very close eye on this
installation, partly through continuous contact with the people here
at Girvan and of course through the EDEN data-link which is providing both the customer and ourselves with vital operational information.” EDEN, Siemens’ Electronic Data Exchange Network
installed at the plant, not only allows essential data on the gas turbine-based installation to be collected, viewed and analyzed to
provide trending information, but also automatically generates reports, which help in planning custom-designed maintenance
regimes within Siemens’15-year maintenance contract. This enables
the plant to be run continuously, at full-rated output under base
load conditions, 24 hours a day, 7 days a week, for a total of 50 weeks
in every year, with just two weeks annual shutdown for essential
maintenance.
As Stirrat points out, “Data from this 24/7 monitoring system not only
helps us and our customer to run the plant at optimum efficiency
and reliability, but is also providing us with information that will
help in the future strategic planning of similar industrial heat
and power plants. The system also provides the customer with an
on-line helpdesk, in case of any unforeseen problems.”
CLEAN, GREEN, PROFITABLE PARTNERSHIP
As well as meeting its entire requirement for electricity from the
CHP plant, the distillery exports around 30 per cent of the generated output to the local grid network as a revenue-earning commodity. In addition to significant savings on the total energy
bill since changing from heavy fuel oil and mains electricity to cleanburn gas-fired boilers and gas turbine-powered CHP, Grant’s
have also become eligible for an 80 per cent rebate on the Climate
Change Levy, a fuel tax imposed on industry by the UK government to reduce greenhouse gas emissions by promoting energy
efficiency. The rebate is awarded only to CHP plants certified
under the CHP Quality Assurance Programme (CHPQA) as “good
quality combined heat and power schemes.” According to
Andrew Kean, Engineering and Maintenance Manager, the rebate is
a useful additional benefit, “but the main advantage is being
able to generate our own power cleanly and efficiently,” he says.
“We went through a very steep learning-curve to become an
independent power producer, but we have been helped at every step
by the people at Siemens and the company has proved to be an
excellent partner.”
In the 4 years since the CHP plant was installed the initial capital
investment has been completely recovered through savings in fuel
and operating costs, with power now being exported at a profit.
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