Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Chemical and Biochemical Engineering

Supervisor

Dr Chunbao (Charles) Xu

Abstract

Agglomeration of bed materials at high temperature is one of the most important and challenging problems for fluidized-bed biomass boilers for thermal/power generation. Inorganic alkali components from the fuel can be problematic as they form low-melting alkali compounds. In the present study, the critical amount of liquid (molten ash in real biomass boiler operations) that would result in severe bed agglomeration and defluidization was studied in two small pilot-scales bubbling fluidized bed (BFB) rigs, one operated at room temperature using glycerol-water to simulate molten ash and the other operated at elevated temperatures using low melting-point salt (KOH) to simulate molten ash. It was found that in the fluidization systems studied the critical liquid amount causing bed agglomeration is likely 0.2-0.5 wt% (in relation to the weight of bed material loaded) and 0.7-0.8 wt% would cause severe channeling and very poor fluidization conditions.


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