12,000 Hours of Operation with Oxygen-Carriers in Industrially Relevant Scale (75,000 kWth).

Journal article, 2017

Oxygen carrier aided combustion (OCAC) is a novel combustion method and a spin-off from chemical-looping combustion (CLC). The core of the technique lies in the utilization of an oxygen carrier (OC) as bed material, and the purpose to enhance the distribution of oxygen in fluidized bed (FB) boilers. The concept combines the robustness of the well-established technology FB boilers with the novel features of oxygen active properties introduced by the OC. Due to several similarities, the OCAC concept can also contribute with knowledge in a transitional path for the scale-up of other chemical-looping techniques, such as CLC, from lab to industrial scale. In this work, the first experiences are presented where a 75,000 kWth CFB-boiler has been operated with ilmenite (FeTiO3) as bed material during 12,000 hours with municipal solid waste as fuel. The investigation shows that ilmenite can replace the commonly used bed material silica-sand without any retrofitting of boiler equipment, and that ilmenite enhances the mass transfer of oxygen inside the furnace. The results show that ilmenite can drastically reduce the amount of carbon monoxide in the flue gas, even when the furnace is operated with an oxygen concentration that is lower compared to ordinary silica-sand operation. Even though still being in the early stages, this concept can contribute to overcome the threshold of understanding the mass transfer and mixing conditions in industrial conditions to enable scale-up of CLC.