The steam turbine to be supplied by Alstom to E.ON’s new Maasvlakte hard-coal-fired power plant in Rotterdam, under a contract signed in May, will be the largest steam turbine ever manufactured by Alstom for a fossil fired station. It is also perhaps the largest machine to date for a hard coal plant with such advanced steam conditions: 275 bar/596.4°C, live steam; 58 bar/619°C, reheat steam; overall plant net efficiency over 46%.
The new steam turbine is the second of four 3000 rpm (50 Hz) machines being supplied to E.ON by Alstom under a “Convoy” ordering scheme, the first being for Datteln 4 in Germany, and the other two for Staudinger 6 (also in Germany) and the Port of Antwerp in Belgium.
These other three Convoy projects will use four-casing (HP, IP, 2LP) steam turbines rated at 1100 MWe gross, whereas Maaslavkte will employ a five-casing (HP, IP, 3LP) machine rated at 1113 MWe gross.
The additional 13 MWe is possible at Maasvlakte because of the good cooling conditions that prevail at the harbour site, with an average cooling water temperature of 12°C and the use of direct seawater cooling, without the need for cooling towers (which are typically employed at central European sites).
The HP, IP and LP modules making up the four Convoy steam turbines are identical, but Maasvlakte has three LP casings rather than two, to accommodate the larger volume of steam that results from the lower exhaust pressure of the LP section due to the lower cooling water temperatures.
The LP casings employ 49in Ti last stage blades, providing a steam exhaust area of 13.2 m2 per flow.
The Alstom scope of supply at Maasvlakte will include, as well as the steam turbine and generator, condensers and auxiliaries, an integrated 1×100% 45 MW boiler feed pump turbine.
Construction is due to start in August 2010, with provisional acceptance certificate expected in December 2012 following a 56 day trial run.
The new plant, Maasvlakte Power Plant Unit 3 (MPP3), to give it its full title, will be built alongside the existing twin-unit 1040 MWe Maasvlakte power plant. Like the existing units the new plant is expected to co-fire biomass (for which the site has good transport logistics). Also, as with other E.ON fossil new build projects, it will be built “capture ready.”
The E.ON Convoy steam turbines are, in the Alstom nomenclature, of the STF100 type, while the associated 4-pole generators are of the Alstom Gigatop type.
