long an net power station
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ongannet Power Station at
Kincardine-on-Forth is the
second largest coal-fired
power station in the UK and
one of the largest in Europe.
It is a coal-fired station with
an installed capacity of four 600
megawatt (MW) units. Operating at full
load, it can produce enough electricity to
meet the needs of two million people.
Longannet, with its landmark 183 metre
chimney, has played an important role inmeeting Scotlands energy needs since
1972, providing electricity for
businesses, transport, homes, hospitals
and schools throughout south and central
Scotland.
Electricity generated at Longannet is also
sold in the wholesale markets in England
and Wales and, since December 2001, to
Northern Ireland. The power is exported
via a system of high voltage transmission
lines which is linked to other networks
across the British Isles. Longannet
occupies a site of 89 hectares on the
edge of the River Forth near Kincardine
Bridge. Part of the station was built on
land reclaimed from the estuary using ash
from Kincardine Power Station, which
stood nearby until its demolition in 2001.
In 2000-2001 Longannet achieved the
highest generation output in its 30-year
history, supplying more than 12,250
Gigawatt hours, with coal burn for the
year topping five million tonnes.
Significant investment continues to be
made in the station to improve its
reliability, flexibility and environmental
performance.
Longannet Power Station,
Kincardine-on-Forth, by Alloa,
Clackmannanshire, FK10 4AA.
Tel: 01259 730631
LONGANNET POWER STATION
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The turbines have two parallel lines of rotors
(rotating shafts fitted with rings of blades)
each turning the electromagnet of a 300 MW
electrical generator at 50 revolutions a
second. There are many rings of blades on
both lines of rotors. To allow for the
expansion of the steam through the turbines,progressively larger blades are fitted towards
the low pressure ends of the machines. The
largest blades are 914 mm long.
the turbine blades causes the
turbine shaft to spin at high
speed. At the generator end
the spinning shaft of the rotorrotates at 3,000 rpm within
the tightly-fixed coils of the
stator, creating electricity.
The steam is returned for
reheating and then directed to
the intermediate pressure and
then the low pressure
cylinders of the turbine.
Afterwards the steam is
condensed back into water
using cooling water from theForth Estuary up to 327,000
cubic metres (72 million
gallons) every hour. This water
is later returned to the river.
to the high pressure cylinders of the
turbines. The steam is fed to
turbogenerators where the force of it striking
Driving force for industry, commerce
FUELLongannet burns Scottish coal from
Scottish opencast operations and other
sources. This is delivered directly to
Longannets coal store which can hold over
two million tonnes.
Coal is transferred from the storage area tobunkers in the boiler house by a
one-and-a-half-kilometre long conveyor
system. From the bunkers, the coal goes
into roller mills which pulverise the coal to a
fine dust, the consistency of face powder,
before it is mixed with preheated air, blown
into the furnaces and burned at very high
temperatures. Each of the four boilers is
served by eight pulverising mills.
WATER FOR STEAMAND COOLINGInside each of the boilers at Longannet is a
very large number of tubes which are filled
with water. The water used is taken from
the local towns water supply and purified
further by the stations water treatment
plant to avoid furring up the boiler.
As the very hot gases from combustion of
the coal pass over the water-filled tubes the
water boils and forms steam.
The steam up to 1,800 tonnes an hourper boiler is produced at a pressure of
169 bars. This is super heated to a
temperature of 568 C before being piped
The central control room is the nerve centr
introduced a revolutionary PC-based control
degree of automation.
LOMIS, pictured above being operated, ena
processes from starting up and shutting doprocessing. Operators can check on any as
any time, with just a few clicks of a mouse.
ensured via a sophisticated protection syste
The Nerve Centre of
The power of Scotland ... from left, Lstore, a Low NOxBurner arrives forturbine hall, big enough to accomm
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and homes
technique involves passing natural gas at
high velocity over the coal flame, causing a
chemical reduction which converts NOx into
elemental nitrogen and water vapour. When
used in conjunction with Low NOx Burners, it
can cut emissions of NOx by up to 80%. It
also reduces emissions of sulphur dioxide,dust and ash by around 20% and cuts CO2
emissions by 8%. The technique was
developed by ScottishPower in association
with a number of international partners at
Longannet Power Station between 1993 and
1998, with assistance from the EUs
THERMIE programme.
The environmental value of Gas Reburn was
recognised by a Queens Award in the
Sustainable Development category in 2001.
Global Climate Change
The combustion of fossil fuels, such as coal
and oil, causes emissions of carbon dioxide
(CO2) the most abundant of the greenhouse
gases which have been linked with long term
climate change. ScottishPowers Generation
business is addressing this issue by ensuring
a balanced mix of generation, including wind
and hydro power as well as coal and gas.
At Longannet, steps have been taken to
reduce CO2 emissions by improving thethermal efficiency of the plant and through
the use of our Gas Reburn system, where
natural gas displaces 20% of the coal.
ENVIRONMENTLongannet Power Stations Environmental
Management System is accredited to two
key standards, the international standard
ISO 14001 and the EUs Eco-Management
and Audit Scheme (EMAS). The station
addresses key environmental issues in anumber of ways:
Acidification & Air Quality
Emissions from coal-fired power stations
such as sulphur dioxide (SO2) and oxides of
nitrogen (NOx) can cause acid rain. This is
associated with damage to eco-systems,
especially watercourses. Both SO2 and NOx
have been linked with respiratory irritation in
humans. Longannet uses mainly Scottish
coal which is naturally low in sulphur.However, the station is taking steps to
reduce SO2 emissions further through the
planned installation of Flue Gas
Desulphurisation (FGD) technology. The
technique chosen by Longannet, known as
Seawater Scrubbing, does not employ
quarried limestone but instead uses
seawater to dissolve SO2 from the boiler flue
gases. A study at Longannet has shown that
the technology has minimal impact on the
environment. To minimise NOx the station hasLow NOx Burners fitted on all four of its units
and has developed and proven a pioneering
NOx reduction technique, Gas Reburn. This
he power station. Longannet
em, LOMIS, in 1999, providing a high
the control and monitoring of all
enerating units, to on-line dataof the electricity generation process at
integrity and safety of operations is
ur Flagship station
annets massive coalallation and thee an ocean liner
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Electric experience
for our visitorsThousands of people have flocked to
Longannet Power Stations Visitors
Centre since it opened in 1998.
The Centre explains, through a host of
interactive displays, how electricity is
produced, covering the entire process
from coal mining to the transmission of
electricity and the disposal of ash.
There are also sections on the
environment and ScottishPowers
renewable energy operations.
Visitors to the Centre can also see inside
Longannets massive turbine hall big
enough to accommodate an ocean liner from the viewing gallery.
DUST
AND ASH
Generating electricity from coal produces
a significant amount of dust and ash.
Electrostatic precipitators capture dust
from the flue gases and prevent it
reaching the atmosphere.
The ash produced is of two types, thelight and more abundant Pulverised Fuel
Ash (PFA) and the heavier Furnace
Bottom Ash (FBA).
During recent years much of the ash
produced at Longannet has been
sold by ScotAsh, our joint
marketing venture with Blue Circle,
for use in construction and
products such as grout and cement.
Ash storage facilities, pictured above,
are in place at the station.
The remainder is transferred to ash
lagoons at Valleyfield nearby. Here it
accumulates, dries out and eventually
creates land, which is capped and
planted for amenity use by the
local community.
The lagoons are part of the
wider Torry Bay Local Nature
Reserve and ScottishPower
sponsors a full-time countryside
ranger to manage the lagoons in
the interests of biodiversity.Valleyfield is a haven for wildlife,
especially birds, along with butterflies,
such as the spectacular Peacock, below,
dragonflies, damsel flies and small
mammals. A leaflet on wildlife at the
lagoons has been produced and further
information is published in Longannets
EMAS Statement and the annual
Generation Environmental Factsheet.
TRANSPORTING ELECTRICITY
Electricity from Longannets generators is
fed into transformers which step up the
voltage from 17 to 275 kilovolts (kV). The
electricity passes through the switch
house beside the main building and is
sent out via overhead transmission lines
to transforming and switching stations on
ScottishPowers transmission network.
The high voltage transmission network
carries electricity at high voltage to
population centres. The voltage is then
stepped down at substations before it
passes into local distribution systems.
WASTE DERIVED FUELLongannet is involved in a project to
achieve useful energy recovery fromwaste derived fuel (WDF). The lightweight
granulised fuel is made from heat-treated
and dried sewage sludge at the Daldowie
sludge drying facility near Glasgow.
Up to 65,000 tonnes of WDF, which has
an energy content similar to brown coal,
will be burned along with coal at
Longannet Power Station to produce
electricity, combining waste disposal with
useful energy recovery. The project
received a Gold Award for its
environmental benefits in the UK-wide
Green Apple Awards during 2001.