Metso and Fortum's joint development work on oxyfuel combustion technology makes headway
In a joint R&D project, Metso and Fortum have developed oxyfuel combustion technology that aims to reduce the CO2 emissions of power plants. In 2010, Metso's 4-MW test plant in Tampere, Finland, was modified for oxyfuel combustion, resulting in the biggest known oxyfuel combustion process based on circulating fluidized bed technology in the world. Circulating fluidized bed boilers can be operated with a wide range of fuel types, such as coal, biomass and a mixture of fuels. The pilot has come to an end and the results of the project will be evaluated during 2011.
The joint project between Metso and Fortum involves research into switching over from air combustion to oxygen combustion. In oxyfuel combustion, the flue gas consists of almost clean water vapor and CO2, which can be captured. Adding a carbon dioxide recovery system to a biomass-fired power plant creates a carbon sink that abates climate change.
During the project, an international research cooperation network was established. Without such a network, it would be impossible to realize a project of this kind, which require extensive know-how. In addition to Metso and Fortum, the project is partly funded by Tekes, the Finnish Funding Agency for Technology and Innovation.
"We have carried out a comprehensive series of tests ranging from laboratory measurements to continuous pilot-scale tests. In the pilot-scale testing, we focused on developing both the actual boiler process and safe operation of the boiler plant during oxyfuel combustion. Modifying Metso's 4-MW test plant for oxyfuel combustion has been challenging and we are pleased with what we have achieved. With circulating fluidized bed technology, coal and biomass can be co-fired, thereby turning the power plant into a carbon sink," explains Jussi Mäntyniemi, General Manager, Technology at Metso's Power business line.
"Fortum has been very pleased with how the project has proceeded. By altering Metso's test equipment for oxyfuel combustion, we have received a lot of new information in terms of the future opportunities that the technology offers. The tests provide both empirical data and new information concerning the operation of the plant," says Marja Englund, manager of the project at Fortum.
In oxyfuel combustion, process fuel is combusted with a mixture of pure oxygen and recirculated flue gas instead of air. After cleaning, the flue gas consists of water vapor and CO2. Oxyfuel combustion can be used in circulating fluidized bed boilers that can be operated with a wide range of fuel types, such as coal, biomass and a mixture of fuels.
Metso is a forerunner in developing innovations and apart from contributing to research in oxyfuel combustion, Metso is also involved in developing new technologies for torrefaction, biogasification, pyrolysis and LignoBoost that are important energy solutions for the future.