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Drax FGD Plant - Supporting the Process

In 1988 National Power undertook an eight year project to install a flue gas desulphurisation plant (FGD) at Europe's largest coal-fired power station at Drax in North Yorkshire. This would neutralise over 250,000t of annual sulphur emissions from the boilers; the scheme was vital to reducing Britain's contribution to the effects of acid rain.

Drax Power Station, United Kingdom
Drax Power Station, United Kingdom

The Drax 400MW power station has six large boilers and generates one tenth of Britain's total energy demand. The FGD plant diverts the flue gases from each pair of boilers through a large cylindrical tower where they are scrubbed with a limestone slurry: most of the sulphur dioxide is removed, thus cleaning the flue gases and producing high quality gypsum. Every week at full load, the power station imports 10,000t of crushed limestone and produces 15,000t of gypsum that goes for manufacture into plasterboard. To support the new flue gas ductwork and piping, and provide the frames for the absorber towers and the buildings for limestone and gypsum required over 23,000t of diverse structural steelwork. Cleveland Bridge was awarded the sub-contract to detail, supply and erect this steelwork over a three year period on site.

The new plant had to be installed without interrupting the power output from the station and each pair of boilers could only be shut down for a fourteen week "outage" every three years. The design of the FGD plant and the construction was dominated by this constraint – this applied equally in the steelwork erection. The particular challenge lay in working around the existing buildings and live ducts and services. Redesign of works to overcome these problems for the plant increased the steel requirement to 27,000t and the numbers of pieces to be erected – with no increase in the time for erection. At one stage, 10,000t of steel were put up in just 10 months. The 60m high absorber buildings contained twice the tonnage originally envisaged and required 50% more lifts.

The new plant was complete in 1996. Cleveland Bridge had a major role in a second FGD plant for Ratcliffe Power Station near Nottingham, undertaking the structural steelwork and the ducting.


Power Generation