Biomass combustion chemistry with oxygen carriers

Forskningsprojekt, 2017 – 2022

Chemical-looping combustion (CLC) is a novel principle for converting hydrocarbon fuels, based on a transfer of oxygen from air to fuel using oxygen-carriers of metal oxide in two interconnected fluidized-beds. The technology is of significant interest for use with biomass, with the purpose to capture atmospheric CO2 and accomplish negative emissions. Such negative emissions are likely necessary to meet current global climate targets. However, biomass includes ash compounds, such as alkali (K,Na) which involves both opportunities and challenges in the application to CLC. Although the subject is of major importance there are essentially no earlier studies and the understanding is poor. To address this lack of understanding this project was conducted, combining the highest competences on CLC, alkali and ash chemistry.

A range of experimental methods and models were employed to characterize the main gas-phase and heterogeneous reaction paths of alkali compounds under relevant reducing conditions. The reactions were studied in the presence of oxygen carrier particles and ash, and under the influence of chlorine, nitrogen and sulfur precursors. 

The project is expected to be of great importance for the further development of chemical-looping combustion of biofuels and the generic understanding of alkali chemistry in this and related processes including oxygen-carrier aided combustion and dual fluidized bed biomass gasification.