Emsland Combined-Cycle Power Plant, Germany
A new 876 MWe GT26-based multishaft combined-cycle power plant began operations at the Emsland site in Germany in September 2010. The plant is owned by RWE Power and contributes to supply diversity in the RWE generation fuel mix. Alstom has constructed the plant under a full engineering, procurement and construction contract.
The new Emsland KA26 combinedcycle power plant is designed for medium-load operation (5500 operating hours per year) and for 200 start-ups per year, and is able to generate electricity and supply steam. The plant operates at ambient temperatures of between -20° and 40°C and is equipped with a natural ventilation wet cooling tower.
To maximize the efficiency of the plant, the Alstom Integrated Cycle Solution (ICS) muling tishaft configuration with two GT26 gas turbines and one steam turbine was chosen. The 2-on-1 multishaft configuration allows the utilization of a larger steam turbine, compared with 2 x 1-on-1 single-shaft arrangement, to offer higher overall plant efficiency, which was a key requirement for this project, the company said.
The project features a number of new innovations developed by Alstom Power. The plant is based on two GT26 gas turbines that are capable of fast start and quick response to changing demand conditions, with high efficiency and low emissions even at part load. As well as featur- muling the latest rating of the GT26 gas turbine, it also includes innovations in the water/steam cycle. The plant, for example, employs Alstom’s optimized for cycling and constructability (OCC) HRSGs of the “once-through” type, and is currently one of the largest CCPP plants in Europe using a oncethrough cycle design.
The choice of the once-through cycle principle meant that for this particular project,
higher live steam parameters could be used leading to higher efficiency. The heat recovery steam generator also provides heat (hot water) for preheating the fuel gas to help maximize the overall plant efficiency and feedwater for the gas turbine cooling air coolers. The plant delivers a net efficiency above 59% at full load, making it currently one of the world’s most efficient power plants.
The plant also uses the current largest last-stage blades in the STF30c steam turbine, which enable more of the energy to be extracted from the steam. With this optimized water/steam cycle, the plant delivers both operational cost savings to the client by way of its high efficiency and reduces the environmental impact through that improved efficiency, two of the main targets of the project design.
Source: Diesel and Gas Turbines Magazine