Experimental results of chemical-looping combustion with NiO/NiAl2O4 particle circulation at 1200 °C

Chemical-looping combustion is the indirect combustion by use of solid medium. This combustion with circulation of solid particles was investigated experimentally. There were two reactors: a reduction column and an oxidation column. The slurry of solid powder of NiO mixed with Al2O3 prepared by a dissolution method was fed into a spray dryer, and a spherical particle of diameter about 97 pm was obtained. The rates of both reduction and oxidation for the produced fine particles were measured in advance by a thermogravimetric analyzer. Then reactions with circulation of reacting solid particles were performed at elevated temperatures. In this paper, the results at 1200 degreesC by use of hydrogen as fuel are presented. The features of the reactions are discussed based on the analyses of the composition of the exhaust gas. Examination of the surface of the solid particles by a scanning microscope revealed that the condition of the solid particle in both reduction and oxidation columns was much milder than that in the TGA experiment, and significant change of the particle was not observed. (C) 2002 Elsevier Science Ltd. All rights reserved.