Wildspur Mills - condensing plant

Image: © Chris Allen Taken: 8 Feb 2003

This mill contained a modern steam engine - a W H Allen & Co Ltd inverted vertical compound steam engine built in 1911 in Bedford. The cylinders are 13.5" & 19" x 9" and it developed 240 BHP at 428 rpm driving an alternator. It exhausted to a jet condenser with a motor driven Edwards air-pump. It was installed secondhand in this former beam engine house in 1949 and ran until 1970. It was removed in 2004 and is now in store at Ellenroad Engine House. This photograph shows the jet condenser in front of the motor-driven Edwards air-pump. This condensing engine was unusual for a dyeworks. Condensing increases the power by increasing the mean effective pressure in the low-pressure cylinder but it also improves the thermodynamic efficiency (T1-T2/T1) by reducing the exhaust temperature and increasing the temperature drop. However, the latent heat of the exhaust steam is still rejected to the cooling water and does no useful work. By using the steam for process heating, that latent heat is recovered in the process, rather than being used to warm the cooling pond, and the overall cycle efficiency is improved.

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