THESIS FOR THE DEGREE OF LICENTIATE OF ENGINEERING High-Temperature Corrosion Chemistry in Oxy-Fuel Combustion

Drastic cuts in global CO2 emissions are needed to mitigate the global warming if limiting global warming to 2ºC. The power generation sector is largely based on fossil fuels and produces a significant share of the global CO2 emissions. Thus, new power generation processes with drastically reduced CO2 emissions need to be employed to mitigate global warming. Two alternatives which may be part of the solution is the replacement of coal with biomass or to apply the concept of carbon capture and storage (CCS). In CCS the CO2 is captured and processed on site and thereafter transported to a storage location. Oxy-fuel combustion, which has been studied in this thesis, has been demonstrated in large-scale pilot plants (30-60 MW). This work investigates the possibilities to co-combust biomass and coal in oxy-fuel combustion for CO2 capture. Biomass combined with CO2 capture has the potential to contribute to negative CO2 emissions. However, the high temperature corrosion (HTC) and the related K-Cl-S chemistry need to be studied in detail in order to determine the potential consequences for corrosion on heat transfer surfaces. This, since the use of biomass in power generation is problematic due to the relative high content of alkali (mainly potassium) and chlorine. Together these compounds form KCl, a salt which causes corrosive deposits and subsequen