Ultra Super Critical Boilers
Clean coal technology
A substantial part of the world’s growth in power generation will continue to be based on coal for decades. At the same time there is a requirement for reduction of harmful emission from coal fired units and also an increasing demand for limiting greenhouse gas (CO2) emission.
“Clean Coal Technology” faces these requirements and the Ultra Super Critical (USC) power cycle is the ultimate commercial technology, due to its high electric efficiency of just below 50%. It was first demonstrated by BWE more than 15 years ago with a world record electric efficiency of above 47 % and has since proved excellent performance and availability records.
During the 1980’s and 90’s the technology was developed from the subcritical through the super critical to the ultra super critical design with the first two units designed by BWE in commercial operation in 1997 and 1998 and the third unit in 2001. The characteristic of the USC cycle is the steam properties of 600°C temperature and 305 bar pressure. Double reheating has been introduced in order to increase the efficiency and in order to reduce the wetness of the steam in the low-pressure turbine.
Apart from the improvements in the steam cycle and the related development of new materials, there have also been major improvements in the conceptual design of the boiler. Thus the Avedøre unit 2 was the first multi-fuel tower boiler with 800 MWth capacity designed for 100% coal, 100% natural gas, 100% HFO and 80 % wood pellets. The total plant electric efficiency: 51% in a configuration involving preheat from a gas turbine.