Llanelly power station

Llanelly power station, also known as North Dock power station, supplied electricity to the town of Llanelly (Llanelli since 1966) and the surrounding area from 1910 to the late 1960s. The power station was owned and operated by a succession of companies, including the Llanelly and District Electric Supply Company Limited, prior to the nationalisation of the British electricity supply industry in 1948. The power station was redeveloped in the 1920s to meet the increased demand for electricity.

Llanelly power station
CountryWales
LocationLlanelli
Coordinates51°41′33″N 04°10′15″W
StatusDecommissioned
Construction began1910
Commission date1910
Decommission dateLate 1960s
Owner(s)Llanelly and District Electric Lighting and Traction Company Limited
(1910–1924)
Llanelly and District Electric Supply Company Limited (1924–1947)
British Electricity Authority
(1948–1955)
Central Electricity Authority
(1955–1957)
Central Electricity Generating Board
(1958–1970)
Operator(s)As owner
Thermal power station
Primary fuelCoal
Secondary fuelOil
Turbine technologySteam turbines
Chimneys5
Cooling sourceSeawater
Power generation
Units operational1 x 12.5 MW, 1 x 7.5 MW, 1 x 5 MW
Make and modelBritish Thomson-Houston
Units decommissionedAll
Nameplate capacity24 MW
Annual net output83.6 GWh (1946)

History

In 1891 Llanelly Corporation applied for a Provisional Order under the Electric Lighting Acts to generate and supply electricity to the town. This was granted by the Board of Trade and was confirmed by Parliament through the Electric Lighting Orders Confirmation (No. 4) Act 1891 (54 & 55 Vict. c. lii).[1] The Corporation did not construct an electricity supply system but transferred the Provisional  Order to J. C. Howell Limited, which was established on 20 December 1905.[2] The Provisional Order was subsequently transferred to the Llanelly and District Electric Lighting and Traction Company Limited when it was established in 1911. This company also supplied current for the Llanelly and District Electric Tramways from June 1911 until the tram system closed in September 1932. In 1924 the Lighting and Traction company changed its name to Llanelly and District Electric Supply Company Limited.[3]

Llanelly power station was constructed at the north east corner of the North Dock (51°41'33"N 04°10'15"W).[4] The location facilitated the supply of coal for the boilers, and cooling water which was drawn from the sea. Further equipment was added to meet the rising demand for electricity; by the late 1920s the station had a generating capacity of 25 MW.[5]

Equipment specification

Plant in 1923

In 1923 the generating plant at the Llanelly power station comprised:[5]

  • Coal-fired boilers generating up to 76,000 lb/h (9.58 kg/s) of steam which was supplied to:
  • Generators:[5]

These machines gave a total generating capacity of 6,250 kW comprising 5,750 kW of alternating current (AC) plus 500 kW of direct current (DC).[5]

Electricity supplies to consumers were:

  • 12,400 & 6,600 Volts, 3-phase, 50 Hz AC
  • 500 & 250 Volts DC
  • 500 V DC Traction current[5]

Plant in 1923–28

New plant was commissioned and installed at the Llanelly power station from 1923 to 1928. This comprised:[6]

  • Boilers:
    • 2 × 40,000 lb/h (5.04 kg/s) boiler, steam conditions 265 psi and 700°F (18.3 bar, 371°C)
    • 2 × 60,000 lb/h (7.5 kg/s) boilers, steam conditions as above
    • 4 × 20,000 lb/h (2.52 kg/s) boilers, steam conditions as above

The boilers were manufactured by Babcock & Wilcox and Yarrow and supplied steam to:

  • Generators:[6]
    • 1 × 5 MW British Thomson-Houston turbo-alternator, generating at 6.6 kV
    • 1 × 7.5 MW British Thomson-Houston turbo-alternator, generating at 6.6 kV
    • 1 × 12.5 MW British Thomson-Houston turbo-alternator, generating at 6.6 kV

The station was supplied with coal via a siding off the nearby dock railway line.[4]

Condenser cooling water was drawn from the sea.[6]

Operations

The supply of electric current in the early years of operation of Llanelly power station was as follows:[7]

Llanelly power station output
Year Electricity supplied MWh
1915 3,479
1916 4,048
1917 4,359
1918 5,675
1919 5,826
1920 6,761

Operating data 1921–23

The electricity supply and consumption data for the period 1921–23 was:[5]

Llanelly power station supply and consumption data 1921–23
Electricity Use Units Year
1921 1922 1923
Lighting and domestic MWh 480 773 715
Public lighting MWh 175 157 178
Traction MWh 454 459 514
Power MWh 5,554 7,853 11,214
Bulk supply MWh 0 0 0
Total use MWh 6,663 9,243 12,620

The electricity loads on the system were:[5]

Year 1921 1922 1923
Maximum load kW 2,655 3,529 3,780
Total connections kW 8,000 9,734 10,670
Load factor Per cent 18.5 17.8 17.7

Revenue from sales of current (in 1923) was £69,818; the surplus of revenue over expenses (1923) was £32,186.[5]

The Corporation tramways ceased operating in September 1932.

The supply of electric current in the inter-war period was as follows:[8]

Llanelly power station output
Year Electricity supplied MWh
1921 7,080
1922 12,605
1923 13,761
1926 12,330
1927 18,300
1929 23,675
1930 24,546
1931 24,092
1932 24,282
1933 26,143
1936 37,952
1938 53,066

Operating data 1946

Llanelly power station operating data for 1946 was:[9]

Load factor per cent Max output load MW Electricity supplied MWh Thermal efficiency per cent
39.7 25,777 83,576 15.15

The British electricity supply industry was nationalised in 1948 under the provisions of the Electricity Act 1947 (10 & 11 Geo. 6 c. 54).[10] The Llanelly and District Electric Supply Company Limited was dissolved, ownership of Llanelly power station was vested in the British Electricity Authority, and subsequently the Central Electricity Authority and the Central Electricity Generating Board (CEGB).[11] At the same time the electricity distribution and sales responsibilities of the Llanelly Electric Supply Company were transferred to the South Wales Electricity Board (SWEB).

Operating data 1954–67

Between 1964 and 1966 the boilers were converted to oil-firing.[12] [13] Operating data for the period 1954–67 was as follows.[6] [14] [12]

Llanelly power station operating data, 1954–67
Year Running hours or load factor (per cent) Max output capacity  MW Electricity supplied MWh Thermal efficiency per cent
1954 4548 24 59,947 14.11
1955 3315 24 39,188 13.83
1956 1992 24 22,122 13.69
1957 1564 24 18,917 13.91
1958 1151 24 13,507 13.75
1961 5.7 % 24 11,933 13.15
1962 4.5 % 24 9,483 13.01
1963 7.0 % 24 14,722 13.64
1967 5.0 % 24 10,413 14.39

The output from the station in MWh is show on the graph.

Llanelly supply district

Following nationalisation Llanelly became an electricity supply district, covering 161.1 square miles (417 km2) with a population of 106,810 in 1958.[6] The number of consumers and electricity sold in the Llanelly supply district was:[6]

Year 1956 1957 1958
Number of consumers 31,685 32,528 33,171
Electricity sold MWh 337,312 344,323 342,339

In 1958 the number of units sold to categories of consumers was:[6]

Type of consumer No. of consumers Electricity sold MWh
Domestic 28,562 30,472
Farms 833 2,397
Commercial 3,344 12,614
Industrial 420 295,439
Public lighting 12 1,417
Total 33,171 342,339

Closure

Llanelly power station was decommissioned in the late 1960s,[15] and was demolished in 1972.[13]

See also

References
  1. "Local Acts 1891". legislation.gov.uk. Retrieved 24 November 2020.
  2. Garcke, Emile (1898). Manual of Electrical Undertakings 1898-99 vol. 3. London: P. S. King and Son. pp. 239, 560.
  3. "Llanelly and District Electric Lighting and Traction". The Times. 1 March 1924. p. 18.
  4. Ordnance Survey Six-inch England and Wales Carmarthenshire LVIII.NW (includes: Llanelly Rural; Pen Bre.), revised 1913, published, 1921
  5. Electricity Commissioners (1925). Electricity Supply – 1920–23. London: HMSO. pp. 228–231, 514–519.
  6. Garrett, Frederick (1959). Garcke's Manual of Electricity Supply vol. 56. London: Electrical Press. pp. A-72 A-126 B-187.
  7. "Llanelly and District Electric Lighting and Traction Company Limited". The Times. 13 December 1921. p. 16.
  8. The Times, 4 April 1928 p. 23, 16 April 1931 p. 22, 28 February 1933 p. 21, 2 March 1934 p. 23, 29 June 1939 p. 19
  9. Electricity Commissioners (1947). Generation of Electricity in Great Britain year ended 31 December 1946. London: HMSO. p. 11.
  10. "Electricity Act 1947". legislation.gov.uk. Retrieved 24 November 2020.
  11. Electricity Council (1987). Electricity supply in the United Kingdom: a Chronology. London: Electricity Council. pp. 45, 60, 69, 73. ISBN 085188105X.
  12. CEGB Statistical Yearbook, 1967
  13. "North Dock power station, Llanelli". coflein.gov.uk. Retrieved 24 November 2020.
  14. CEGB Annual report and Accounts, 1961, 1962 & 1963
  15. The station is in the CEGB Statistical Yearbook 1967 but not in the 1972 edition
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