West Burton power stations

West Burton Power Stations
West Burton Power Station Viewed from the south in November 2006
Location of West Burton Power Stations in Nottinghamshire
Country	England
Location	West Burton, Nottinghamshire
Coordinates
Status	Operational
Construction began	1958 (A station) 2006 (B station)
Commission date	1968 (opened by Roy Mason)
Construction cost	£600 million (Gas)
Owner(s)	EDF Energy
Operator(s)	Central Electricity Generating Board (1968-1990) National Power (1990-1996) Eastern Group (1996-1998) TXU Energy (1998-2001) London Power Company (2001-present)
Thermal power station
Primary fuel	Coal
Tertiary fuel	Gas
Power generation
Nameplate capacity	2,000 MW 3,270 MW (2013 on)
Website www.edfenergy.com
grid reference SK791855

The West Burton power stations are a pair of power stations on the River Trent near Gainsborough, Lincolnshire, England. One is a coal-fired power station, which was commissioned in 1968, and the second is a combined cycle gas turbine power station, commissioned in 2011. Both stations are owned and operated by EDF Energy. The station has been accredited as an Investor in People since 1995 and ISO accredited (ISO 14001) for its environmental management system since 1996. The power station won a RoSPA President’s Award in 2006, 2007 and 2008. The site is the furthest north of series of power stations in the Trent valley, being 3.5 miles (5.6 km) downstream of the Cottam power stations. The Sheffield to Lincoln Line supplies the station with coal.

History

It is built on the site of the deserted medieval village of West Burton. The station was commissioned between 1967 and 1968. It was originally operated by the CEGB and then run by National Power after privatisation, until April 1996 when it was bought by the Eastern Group which became TXU Europe. In November 2001 when the price of electricity was low and TXU Europe had severe financial problems, it was bought by the London Power Company for £366 million. The station is now run by EDF Energy.

In 1988 the then chairman of the CEGB Walter Marshall, Baron Marshall of Goring announced a 2 x 900 MW coal-fired power station fitted with FGD to be known as 'West Burton B' would be built on the site. The plan was later shelved just before privatisation. Prior to privatisation West Burton was the last CEGB power station to be awarded the Christopher Hinton trophy in recognition of good housekeeping. The station has a Discovery Centre to educate local school children and also has the oldest mound of FGD gypsum in the UK, part of an experiment set up by CEGB scientists in 1988. In the summer of 1998 Station Manager Derrek Wells was awarded the OBE for his services to the power industry.

In 1977 a British Rail Class 56 locomotive was officially named in front of the coal plant control block as 'West Burton Power Station' number 56009 later re-numbered to 56201.

Architecture

The principal architects for the buildings were Architects Design Group (ADG) from Baker Street, Nottingham. Heliodon modelling was used to determine the visual and psychological impact of the structures to be used on site due to their scale. This created a Zone of Visual Influence (ZVI) a system pioneered by the CEGB for the creation of future 2000 MW power stations in the 1960s. The tower layouts exploit line and lozenge formations. The opposite pairs of the lozenge group were coloured light and dark to avoid tendency of shapes to coalesce when viewed at a moderate distance. The offset tower of the line group has a light colour with intense hue which acts as a nodal point. The main building colours are limited to black, white and yellow. The ancillary buildings are grouped around two courts through which the approach road passes. The Executive partner for (ADG) was Rex Savidge and Architect in charge was John Gelsthorpe assisted by Norman Simpson.

West Burton was granted an award by the Civic Trust for its ‘outstanding contribution to the surrounding scene.’ The Civic Trust, announcing the 82 awards it made in 1968 from more than 1,400 entries from 94 counties in the United Kingdom described West Burton as ‘an immense engineering work of great style which, far from detracting from the visual scene, acts as a magnet to the eye from many parts of the Trent Valley.’

Construction

Work began on site in 1958 by the Northern Project Group a department within the CEGB the construction was overseen by resident engineer Douglas Derbyshire who had recently completed the build of the nearby High Marnham Power Station. In a bid to combine efforts at the design and construction stages the Boiler and Turbo-generator plant were replicated at Fiddlers Ferry power station located in Cuerdley, Cheshire, in North West England.

The Shah of Iran visits West Burton Power Station in a Westland Whirlwhind of The Queen's Flight escorted by the Lord Lieutenant of Nottinghamshire in 1965

The consulting engineers for the project were Merz & McLellan and the main contractor on site was Alfred McAlpine with steelwork designed by the Cleveland Bridge & Engineering Company.

The station was the first 2000 MW to be constructed in the United Kingdom and was visited by the then chairman of the CEGB Christopher Hinton on 27 November 1964 the instigator of the new 500MW units. It subsequently attracted visitors from around the world including Mohammad Reza Pahlavi the Shah of Iran who was escorted around the site by Robert Laycock the Lord Lieutenant of Nottinghamshire on 6 March 1965. The station was officially opened in 1969 by the Minister of Power Roy Mason, Sir Stanley Brown the then Chairman of the CEGB, Arthur Hawkins Director of the Midlands Region and Douglas Pask director of the Northern Project Group.

Specification

The power station provides electricity for around two million people, and is situated on a 410-acre (1.7 km²) site. Coal for the power station, like Cottam, came from the Welbeck colliery at Meden Vale until it closed in May 2010. The station's other supplier, Thoresby colliery, is expected to last longer. The station connects to the National Grid, like most similar sized coal power stations, via a transformer and substation at 400 kV. The chimneys of West Burton Power Station are 200 metres (660 ft) tall.

Turbo-Generator

The 500 MW single shaft machines manufactured by English Electric, are arranged lengthwise along the turbine hall, which is 259.08 m (850 ft) long by 39.624 m (130 ft) wide by 26.060 m (85.5 ft) high. The overall length of each machine is 49.53 m (162.5 ft). The generators are rated at 500 MW, 22 kV at 0.85 power factor. Steam conditions at the H.P. turbine stop valve are 2,300 p.s.i.g (158.6 bar). at 566 °C with a single reheat stage to the I.P. cylinder of 565 p.s.i.a. (38.96 bar) at 566 °C. The turbine has a design steam consumption of 6.3932 lb/kWh, including reheating, feed heating, and boiler feed pump drive and an overall heat input of 7,543 BThU/kWh.

A novel mounting arrangement was adopted for the turbo-generators. The L.P. cylinders are supported on two steel beams about 22.098 m (72.5 ft) long, which bridge between the concrete blocks at the H.P. steam and generator ends of the sets. The fabricated condenser structure was welded directly to the underside of the L.P. frame using a pre-heated welding technique. This provides a compact arrangement of the condenser and the main set and is a major factor in the reduction of size related to the output of the machines, which is a striking feature of the turbine hall. The L.P. frame is supported at its corners, each of the supports taking about 203.2 tonnes (200 tons) in weight. The overall weight of the frame and condenser structure is some 2,235 tonnes (2,200 tons) of which 1,422 tonnes (1,400 tons) is supported on the bottom of the condenser by the mounting springs.

The condensers were fabricated on site by English Electric from sub assemblies and welded to the bridge beams supporting the L.P. cylinder. There are over 40,000 9.144 m (30 ft) long, 25.4 mm (1 in) diameter aluminium/brass tubes in each condenser, giving an effective surface area of 27,870 m² (300,000 sq ft) the equivalent of 3.9 football pitches. Operation is at 1.3 inHg with 1,023 m³/min (225,000 gal/min) of cooling water at 15.5 °C. Steam is passed to the condenser at over 963.9 t/hr (2,125 klb/hr). Since contamination of the condensate by the cooling water must be avoided, a double tube plate construction has been adopted in which the condenser tubes are expanded into an extra tubeplate in addition to the one forming the side of the water box. The narrow space between the plates is filled with demineralised water, supplied from a header tank from 48.768 m (160 ft). This provides a pressure considerably higher than the 20 p.s.i.g. developed in the cooling water system, so that any leaks on the tube end plates will be supplied from the header tank.

The single shaft five cylinder impulse-reaction turbine has a double flow arrangement for the I.P. cylinders as well as for the L.P. cylinders. There are double casings on H.P., I.P., and L.P. cylinders, and the last stages of the L.P. are fitted with 914.4 mm (36 in) blades.

Stop valves and governor valves are situated at the inlet to the H.P. strainers and I.P. turbine. There are four 228.6 mm (9 in) bore main steam pipes, and four 431.8 mm (17 in) bore pipes on both the hot and cold reheat circuits to the turbine. In view of the size and increased volume of pipework compared to earlier designs, special attention was paid to mounting the valve chests as close to the machine as possible to reduce the stored energy effect of overspeed. For the H.P. valves this is done without actually mounting the valves on the cylinder, thus avoiding complication of the H.P. casing.

The generator stator winding is water cooled at 2.155 m³/min (474 gal/min) and the stator core and rotor winding are cooled by hydrogen at 60 p.s.i.g. circulated by a blower on the shaft. To reduce the transport weight, each stator consists of an outer gas tight enclosure, which carries the hydrogen coolers and the end brackets which support the rotor bearings, and an inner stator comprising the magnetic core and windings.

Because the coupled shafts 'hang' in a curve, which may be 12.7 mm (1/2in) lower at the centre than at the ends, the complete generator must be adjusted with its outer end slightly higher than the end adjacent to the turbine, so that the turbine and generator coupling faces are parallel, and peripherally true before they are bolted together. This adjustment is achieved to an accuracy at the coupling face of 0.0127 mm (0.0005 in).

Feed system

There are three stages of H.P. feed heating with six heater shells arranged in parallel pairs, a de-aerator and three low pressure heaters. Steam is bled from the main turbine H.P. exhaust to drive the main boiler feed pump turbine, which exhausts to the feed heating system to improve the overall cycle efficiency.

The main feed pump turbine is a 15,150 hp single-cylinder impulse machine with steam conditions, at the h.p. exhaust, of 610 psia (42.06 bar) at 366 °C. The rotor has eleven stages and the steam is exhausted to the de-aerator at 52 psia. (3.585 bar) at 144 °C. The pump is a six-stage centrifugal unit with a capacity of 1.588 kt/hr (3,500 klb/hr). Two 50 per cent duty start-up and standby feed pumps, electrically driven, are also provided.

Boiler

The four boilers have single divided furnaces and assisted circulation. Each has a maximum continuous rating of 1.565 kt/hr (3,450 klb/hr) and a design efficiency of 90.75%. Built by International Combustion, the design is similar in many respects to that of the now redundant 550 MW ICL boiler at Thorpe Marsh which had two furnaces with centre division walls. There are six stages of superheat and three stages of reheat in each boiler, with superheat and reheat stages mixed in position. As a result of operating experience on boilers of this size at Thorpe Marsh it was found that higher superheat temperatures and larger pressure drops than the design figures occurred in the boiler. New materials had to be employed for the superheat sections and the tube paths redesigned as a result.

The boilers are 53.65 m (176 ft) high and the main suspension girders span 27.43 m (90 ft). The total downward thermal expansion is about 228 to 305 mm (9 to 12 in). The superheater output is at 569 °C 2,400 p.s.i. (165.5 bar). The reheater has inlet and outlet temperatures of 364 and 569 °C with an inlet pressure of 592 p.s.i. (40.82 bar) and steam flow of 1.243 kt/hr (2,740 klb/hr). The single steam drum weighs 162.6 tonne (160 tons).

The furnace is tangentially fired with eight burner boxes, each with six burners, together with oil burners in each box for lighting up. Steam temperature control is by electrically operated tilting burners and by electro-hydraulically operated spray desuperheaters, giving a control range of 70 to 100% of the maximum continuous rating. There are four desuperheaters for each of the superheater and reheater circuits. The economisers have a heating surface of 44,970 m² (484,000 sq ft).

There are two forced and two induced draught Davidson fans per boiler. The f.d. fans are driven by constant speed 1,300 h.p. motors at 596 r.p.m. and are rated at 11,380 m³/min (402,000 ft³/min).

A saving in the overall size of the boiler house building, which measures 259.69 m (852 ft) long, 44.2 m (145 ft) wide and 60.05 m (197 ft) high, was achieved by arranging the pulverised fuel mills in two rows between adjacent boilers instead of in a line along the length of the boiler house as usual. This meant that coal conveyors at right angles to the trunk conveyor had to be installed for each line of mills, but the cost of these was more than offset by the saving in capital on the building. There are six roller type mills per boiler, each powered by a direct coupled 635 h.p. motor at 985 r.p.m. The coal is fed to the mills by Lopulco chain feeders with induction regulator speed controllers.

Separated over-fire air (SOFA) burners were installed on all four of the station's units in 2007 to meet European Union nitrogen oxide emission legislation. The burners were installed by GE Energy.

Cooling water system

The eight cooling towers, built by Davenport Engineering Ltd. of Bradford, have a capacity of 30,690,000 l/hr (6,750,000 gal/hr) and a normal cooling range of 8.5 °C (47.3 °F). The towers are 106.7 m (350 ft) high with internal diameters at sill level of 86.56 m (284 ft) and at the top 49.99 m (164 ft) and 46.33 m (152 ft) at the throat. Cooling tower C1 was fitted with reinforced concrete tension rings in 2000 to provide additional stability to the structural shell.

Cooling water is circulated by Allen Gwynnes horizontal centrifugal bottom suction cooling water pumps, with four in each of the two pump houses. Each pump has a capacity of 545,500 l/min (120,000 gal/min) with a net generated head of 23.16 m (76 ft). Make-up water from the river Trent is pumped by four 45,460 l/m (10,000 gal/min) vertical centrifugal pumps).

Coal store

Coal arriving at the station is discharged from the permanently-coupled 29.03-tonne-capacity (32 tons) hopper wagons, the bottoms of which are opened by automatic lineside gear while the train moves through at 0.8 km/hr (0.5 mph). The four W & T Avery Ltd. weighbridges, two on each of the two rail tracks using electronic weighing heads, record the weight of the coal wagons loaded and empty and summate the total quantity of coal delivered. The coal store on the site has a maximum capacity of 1,814,000 tonnes (2 million tons) at 9.14 m (30 ft) deep, it is used to deposit all surplus coal and to build up stocks.

West Burton Power Station was used as a testing ground for the Merry-go-round train system in 1965 which would be introduced at all 500 MW and above power stations.During the stations' early life in the 1970s and under the merry-go-round train agreement with British Rail and the National Coal Board no deliveries were made at the weekends. The coal store has capacity for over three month's operation of the station. When discharged from the railway wagons, the coal drops into the hoppers immediately under the track where it is scooped out evenly along the length of the hoppers by remotely operated paddle feeder machines. These deposit the coal on a two twin deep-trough belt conveyors 1371.6 mm (54 in) wide, each with a capacity of 1,361 tonnes/hr (1,500 tons/hr) at 137.16 m/min (450 ft/min). The belt conveyors feed coal via the screening and crushing plant, where it is also passed through magnetic separators, to the transfer tower.

From this tower the coal can be passed to stock via a boom stacker or direct to the boiler house. There are seven belt weighers installed in the conveyor system, to enable checks to be made on the coal quantities passed to stock, re-claimed from stock and finally passed to the boiler house bunkers. The four 2,722-tonne-capacity (3,000 tons) boiler bunkers will hold enough coal for overnight operation without drawing from the coal store. The normal maximum consumption of each boiler is approximately 181.4 tonnes/hr (200 tons/hr).

Gas turbine

Four 17.5 MW gas turbine driven alternators were installed at the station. They supply power to the auxiliaries in the event of the grid system frequency varying outside suitable limits for the plant. A low frequency relay, which can be pre-set between 49 and 50 cycles per second, initiates the starting operation on the gas turbines; normally the setting is 49.5 cycles per second. The load is automatically taken over by the gas turbines and the auxiliary plant is isolated from the grid supply, provided the system frequency has by then fallen to approximately 48 cycles per second. The gas turbine generators can also be used for augmenting the station output at peak load via the unit transformers.

If the station becomes completely isolated from the grid system, the gas turbines are used to restart any main units that are shut down. This process is known as a black start and is tested annually. Each gas turbine unit consists of an English Electric type EA 3,000 r.p.m. expansion turbine employing two Rolls-Royce Avon type RA29 Stage 6A (1533–51) engines as gas generators, and is directly coupled to the alternator. The alternators, made by English Electric are rated at 11 Kv, 21.9 MVA, 0.8 p.f. lag and have a frequency range of 40 to 51 cycles per second. Two of the four gas turbines were later de-commissioned during the 1990s.

400 kV Supergrid Substation

The 400 kV substation interconnects four generator circuits, six feeders, two inter-bus transformers and includes two bus coupler switches and one main busbar section. The circuits are back to back and are arranged with the generator and interbus transformer connections on the power station side and the line entries on the opposite side of the substation. The current line entries are Bicker Fen-Walpole, Bicker Fen-Spalding North, Keadby 2, High Marnham, Cottam, and Keadby 1.

Civil works

The design of the prototype indoor 400 kV switch house was arrived at by close liaison between electrical and civil engineers before full details of plant and equipment were known. The structural frames are at 21.3 m (70 ft) centres, each frame consisting of five continuous portals, each 23.3 m (76 ft 6 in) wide with a 7.9 m (26 ft) cantilever at each end. The inner portals take the busbars and the two outer portals the breakers. The cantilever gives space for the through bushings and isolators.

There are nine 21.3 m (70 ft) structural bays in the length of the Switch House, making the building 195 m (640 ft) x 132.5 m (435 ft). The site area is approximately 5.26 hectares (13 acres), of which the switch house takes up 2.42 hectare (6 acres). The total weight of the steelwork is about 2,540 tonnes (2,500 tons).

Roof load

The main and longitudinal girders have been designed as welded lattice steel members of sufficient depth to incorporate the access walkways. In addition to transferring the roof load to the columns these girders also have the 'V' strain insulators attached to them. The side framing of the building as well as carrying the wall cladding also supports the wall bushings and provides anchorage for the strainer connections between the turbine house and the switch house. The switch house was designed so as to fit in the architectural treatment of the Power Station as a whole. The plastic-coated aluminium cladding is therefore coloured black on the north and south faces of the building and gold on the east and west. The roof line of the switch house is designed to blend with the 'saw tooth' effect on the turbine house roof. Construction work began in the severely cold winter of 1962/63. The cold weather was turned to advantage as the clay subsoil which is generally unmanageable when wet was frozen solid. Excavation went on uninterrupted on drainage branches during this period. The wet mix base was next introduced over all the site. The object of the wet mix was to apply a firm layer for the construction to be carried on even when subsoil clay was wet. Construction traffic also tended to compact the wet mix therefore improving it as a base for the final topcoat of bitumen macadam.

Steel erection began in June 1963. Erection was carried out by means of two derricks which ran along tracks extending over the length of the switch house. As soon as the steelwork contractor had moved out of the first bays, the civil contractor began work on erecting precast concrete structures, forming trenches and tidying up the surfacing. Access within the switch house was made easier by a decision to lay 228-millimetre-diameter (9 in) ducts to take many of the cables beneath the surface, thus eliminating numerous trenches.

The precast concrete structures proved to be comparatively easy to erect to very close tolerances. On the isolator structures the various concrete members are bolted together using high tensile steel bolts to a pre-determined torque. All in situ concrete is eliminated from these structures. The circuit breaker structures were cast in situ. The contract was started on 21 January 1963 and was substantially completed by 30 November 1964. Access was given to the electrical contractors in April 1964.

132 kV Substation

In addition to interconnecting the supergrid system, the West Burton 400 kV substation also feeds into the local 132 kV network. This connection is made via two 240 MVA, 400/132 kV auto-transformers manufactured by Associated Electrical Industries. The windings consists of a tertiary winding, a common, a tapping and a series winding. They are arranged so that the helical single layer tertiary winding is nearest the core, the continuous disc common winding next, followed by the interleaved full-length helical type tapping winding and the multi-layer type series winding and line shield. A continuously transposed conductor was used to minimise eddy current losses and reduce the space requirement of the windings.

High speed resistor tap changers are provided on the 132 kV side of each transformer, giving a tapping range of plus 15% to minus 5%. The tapping winding has 7 taps which in conjunction with a buck/boost switch provide fourteen steps. The fixed contacts of each of the two rotary tap selector units associated with each phase are connected to one half of the tappings from the windings while the moving contacts are connected to the diverter switches. The diverter switch assembly, together with the transition resistors and operating mechanism is mounted on top of the 132 kV bushing which forms an integral part of the tap changer.

Erection of the transformer was carried out inside a translucent plastic dome, inflated by a small blower. This allowed the work to continue regardless of the weather and thus reduced the time normally taken for erecting large transformers in the open. By working day and night within the plastic dome the time for erection on site was reduced from an estimated 8 weeks to 3 weeks. Completely assembled, each transformer is 14.94 m (49 ft) long, 10.06 m (33 ft) wide, and weighs 325.1 tonnes (320 tons) made up of 154.4 tonnes (152 tons) of steel, 30.48 tonnes (30 tons) of copper, and 19.3 tonnes (19 tons) of insulation and 98,420 Litres (26,000 gallons) of oil. The current line entries for the 132 kV switch house are North Greetwell – Lincoln 1, Retford – Worksop – Checkerhouse 2, North Greetwell – Lincoln 2 and Retford – Worksop – Checkerhouse 1

Control system

In 1996 the first unit was equipped with the Advanced Plant Management System (APMS), a system developed by RWE npower and Thales, and implemented by Capula. All the remainder units followed in later years. The APMS database contains some 16,000 points. Operations staff interact with the system through four main workstation screens, supplemented by a further six overview screens.

Flue gas desulphurisation

In June 2000, work began on the fitting of flue-gas desulfurization (FGD) equipment at the station. FLS Miljo installed the Mitsubishi Heavy Industries wet limestone systems, while Arup Energy and Mowlem took up a design–build partnership to undertake the civil works and construction of infrastructure. The work was completed in October 2003, and had a total cost of £100 million. As part of the new FGD retrofit two new chimneys 200 m (656ft) high were constructed 194 m (636ft) to the north of the existing chimneys, numbers 1 and 2. In January 2003 when the new chimney 2 was erected alongside the old chimney 2 the wind direction changed and began blowing from the north hitting the new chimney 2 first, at a speed of 11.83m/s (26.47mph). This created a vortex and caused the old chimney 2 to start oscillating to a magnitude of 931 mm (36in) at its height of 182.8 m (600ft) and an angle of 600 seconds (0.166 degrees). The old chimneys were later demolished and used as built up ground to form the security gatehouse and parking area at the power station entrance.

Environment

West Burton is currently opted in to the UK Transitional National Plan, placing limits on its sulphur dioxide, nitrous oxides and particulates emissions to a period up to the end of 2020. part of the Industrial Emissions Directive 2010/75/EU which superseded the Large Combustion Plant Directive 2001/80/EC. Under the EU regulations West Burton is classed as two power plants due to the fact of having two chimneys.

Combined cycle gas turbine power station

A £600 million 1,270 MWe CCGT power station, which runs on natural gas, was built next to the coal-fired station. Construction by the Kier Group started in January 2008. It was built on land originally allocated for a proposed 1,800 MW West Burton 'B' coal power station that was to have been built in the 1980s. Privatisation of the electricity industry in 1990 cancelled this scheme. The power station commissioned in 2013, and supplies electricity to around 1.5 million homes. A new 12 mi (19 km) gas pipeline was built to link to the National Gas Transmission System at Grayingham in Lincolnshire. Around 1,000 people were involved in the construction. The plant consists of three 430 MW gas turbines each with a heat recovery steam generator.

Activists from the No Dash For Gas group protesting against the building of the gas plant pleaded guilty to charges of aggravated trespass in February 2013. EDF discontinued a civil lawsuit against them in March 2013.

External links

• Celebrating 40 years of electricity production at West Burton, EDF, 2009
• SOFA system on burners in 2004
• FGD retrofit
• New CCGT power station
• Aerial photograph
• No Dash For Gas ends the UK's longest power station occupation
• EDF Energy opens West Burton gas-fired power station