International NSF project could help reduce CO2 emissions from power plants
University of North Dakota Chemical Engineers Wayne Seames and Gautham Krishnamoorthy are co-principal investigators on a recently awarded international research grant to study barriers associated with oxy-biomass and oxy-coal combustion technologies and their impacts on producing electricity and removing CO2 from the atmosphere.
This four-year, $1-million project is jointly funded by the National Science Foundation in the U.S. and the National Science Foundation of China. The overall objective is to provide information to enable implementation of oxy-combustion of biomass and biomass-coal blends for power generation from power plants. It’s a collaboration of the University of Utah (U.S. lead organization), UND, Huazhong University of Science and Technology (HUST – the Chinese lead organization) and Southeastern University (China).
Seames is a Chester Fritz Distinguished Professor of Chemical Engineering at UND, while Krishnamoorthy is the Ann and Norm Hoffman Associate Professor of National Defense/Energetics. Both men are faculty members in the UND College of Engineering and Mines.
UND’s primary role in the international NSF project is to carry out numerical simulations to compliment the experiments carried out at partner institutions.
In oxy-combustion, oxygen is separated out of air prior to its use in a steam boiler. This generates a nearly pure CO2 flue gas that is easy to reuse or sequester since the CO2 doesn’t have to be separated from nitrogen. The issue here is the “nearly pure” part of the flue gas. A portion of the CO2 is recycled back to the boiler because burning biomass or coal with pure oxygen generates temperatures that are too high for current boiler materials. However, replacing nitrogen with CO2 affects fuel combustion characteristics and ultimately influences burnout and ash deposition. Further, contaminants build up on boiler tubes, reducing heat transfer efficiency and causing corrosion.
This technology is attractive because it can simultaneously produce electricity and remove CO2from the atmosphere, using conventional equipment. But the technology requires a knowledge of ash deposition and heat transfer under biomass oxy-combustion conditions, which are the twin thrusts of this research. The team aims to (1) uncover deposition mechanisms and validate predictions of ash deposition rates and (2) understand how these impact boiler chamber radiation.
The project also explores the use of pressurized combustion systems. These proposed next generation systems may result in increased thermal efficiencies and reduced pollution rates compared to conventional combustors.
The groundwork for this partnership was laid nearly three years ago when Seames participated in a joint U.S.-Chinese workshop focused on sustainable combustion technologies. At the workshop, Seames met Minghou Xu from HUST and they agreed to collaborate on future proposals.
Xu was already collaborating with Utah’s Jost Wendt, who was Seames’ doctoral research advisor in the 1990s. They agreed to team up to develop the project.