Deposition of ash and its effect on heat transfer during the oxy-combustion of biomass and biomass-coal blends.

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1603249 Wendt, Jost The overall objective of this project is to provide information that will enable implementation of oxy-combustion of biomass and biomass-coal blends for power generation. This technology, when followed by carbon sequestration, has the potential to have significant impact because it can simultaneously produce electricity and decrease CO2 emissions, using essentially conventional equipment. This process requires a knowledge of ash deposition and heat transfer under biomass oxy-combustion conditions, which are the twin thrusts of this research. The international team assembled consists of the Universities of Utah (UU) and North Dakota (UND) in the US and Huazhong University of Science and Technology (HUST), and Southeastern University (SEU) in China. Scientific objectives are to: 1) validate predictions of ash deposition rates during the oxy-combustion of biomass-coal blends; and 2) understand how these impact boiler chamber radiation. The hypothesis, based on limited preliminary experimental work, is that ash deposition rates are linearly dependent on the concentration of sub-micron particles (PM1) in the flue gas. In extending the work to oxy-biomass combustion, it is sought to understand formation of both the inner binding layer and bulk layer of controlled ash deposits, and to develop and apply experimental information to refine existing models for predicting the ash layer build up and submicron aerosol formation. These models will be employed in conjunction with high fidelity radiative property models in computational fluid dynamic simulations of the combustion scenarios. The simulations will be validated through coordinated experiments in both the US and China, at various scales, for various fuels, covering a range of combustion conditions, including experimental validation at both atmospheric and pressurized oxy-combustion conditions. This international collaborative project is expressly designed to provide the fundamental knowledge that will help bring this technology into practice, for both first generation (atmospheric pressure) and second generation (elevated pressure) oxy-combustion technologies. A US graduate student will assist in some of the experiments in China while Chinese students will participate in US activities.