Research issues in combustion and gasification of lignite

This paper presents an overview of the combustion and gasification research sponsored by the CRC for Clean Power from Lignite. This research is focused on two distinct areas, gasification of lignite for use in advanced gas turbine cycles and the utilisation of de-watered lignite in existing boilers. Fluid bed gasification is at the centre of a suite of technologies being developed for advanced power generation cycles using Victorian and South Australian lignite, the latter being particularly difficult to utilise on account of its high sodium and sulphur contents. Gasification research at Adelaide is focused on obtaining fundamental reactivity data under gasification conditions to validate and to further develop an existing fluid bed gasification model. The sodium and sulphur in the SA fuel present a special challenge and a considerable part of the research effort is devoted to developing techniques to manage these components. The team is utilising two small gasifiers, one batch and one continuous for this work and is about to commission a new 200-mm continuous fluid bed gasifier. Utilisation of de-watered lignite in existing boilers represents a significant fuel change, similar to the changes from coal to oil (1950-1960s) and oil to natural gas (1970-1980s), which did not occur smoothly. Researchers at Adelaide are currently developing mathematical and physical models for lignite-fired boilers, which, together with the lessons from the past, will equip the industry for the changes with minimum disruption.