(103a) Elutriation, Particle Separation, Fines, Cold Flow, Energy, Fluidized Bed, Bubbling

Chemical looping combustion (CLC) technology is being pursued as a promising clean and high efficiency method of power generation. The basis of CLC technology is to supply the fuel reaction process with oxygen via “oxygen carriers” that are oxidized in a separate air reactor in a recirculating cycle. One challenge with applying CLC to solid fuel is that typical combustion is estimated to produce 1% of unburnt carbon which has the potential to get cycled into the air reactor resulting in efficiency and emission penalties. Therefore, the US DOE has a set a goal to demonstrate that over 90% of the unburnt carbon can be separated from the oxygen carrier being transported back into the air reactor.

To meet this objective cold flow experiments are being performed on a 0.1 m meter diameter bubbling bed with a 0.9 m height to characterize elutriation rates for a binary mixture in a continuous process. A binary mixture of glass beads with a sauter mean diameter of 707 μm and DayGlo plastic particles with a sauter mean diameter of 39 μm were used to simulate the respective oxygen carrier and char ash fines. Steady state conditions were achieved by continuously feeding the mixture into the system with over flow ports at predefined bed heights to maintain constant heights. In addition to standard differential pressure measurements along the riser the time dependent weight of the mixture from the overflow port and the elutriated fines exiting the top of the riser were recorded via scales. In addition the separation efficiencies were determined by post-test sieving of the overflow material. Therefore the fines elutriation rates and efficiency could be analyzed, mapped, and optimized based on the following parameters: riser gas velocity, bed height, binary mixture feed rate, and concentration of fines in the binary mixture.