Longannet Power Station – Turbines

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Longannet Power Station Turbine HallThe turbine hall at Longannet housed four cross-compound generating units arranged in eight turbine lines. There were eight 300 MW generators – one per turbine line. Each of the four units manufactured by English Electric / GEC therefore had a total capacity of 600 MW.

General view of units 2 to 6 in the Longannet turbine hall
General view of units 2 to 6 in the Longannet turbine hall

Cross Compound Turbine Arrangement

Unit 1 high-pressure line in the foreground with the intermediate-pressure line behind.
Unit 1 high-pressure line in the foreground with the intermediate-pressure line behind.

Longannet utilised a cross-compound arrangement of turbines. Each unit had two turbine lines and therefore two generators per unit. One line incorporated a high-pressure (HP) turbine and two low-pressure (LP) turbines. The second line incorporated two intermediate-pressure (IP) turbines followed by two low pressure turbines. The steam was fed into the HP turbine first, then reheated and fed into the two IP turbines on the second line. After expansion in the IP turbines, the steam was finally divided equally between the four LP turbines. This arrangement has advantages in that the individual casings of the turbines can be smaller and has improved efficiency overall.

The boiler feed pumps were supplied by G&J Weir. Each unit had two starting/standby feed pumps and one primary feed pump driven by a steam turbine utilising steam bled from the high-pressure line.

Longannet Generating Units

List of power generating units at Longannet Power Station:

Unit Name Capacity Date
Commissioned
Date
Decommissioned
Turbine/Generator
Manufacturer
Boiler
Manufacturer
Unit 1 600 MW 1972 2016 English Electric / GEC Foster Wheeler John Brown
Unit 2 600 MW 1972 2016 English Electric / GEC Foster Wheeler John Brown
Unit 3 600 MW 1972 2016 English Electric / GEC Foster Wheeler John Brown
Unit 4 600 MW 1972 2016 English Electric / GEC Foster Wheeler John Brown

Turbine Pictures

Boiler Feed Pump Pictures

Unit 1 Starting/Standby Boiler Feed Pumps, with the primary feed pump and turbine behind
Unit 1 Starting/Standby Boiler Feed Pumps, with the primary feed pump and turbine behind

Documents and Schematics

Cross-compound turbine and generator arrangement at Longannet
Cross-compound turbine and generator arrangement at Longannet

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