Investigation of Coal Fueled Chemical Looping Combustion Using Fe3O4 as Oxygen Carrier

Abstract

Chemical-looping combustion (CLC) is a novel combustion technique with CO 2 separation. Magnetite (Fe304) was selected as the oxygen carrier and Shenhua coal (Inner Mongolia, China) as the fuel for this study. The influences of operation temperatures, and coal to Fe 304 mass ratios on the reduction characteristics of the oxygen carrier were investigated using an atmosphere TGA. The sample, comprised of 2.25mg coal and 12.75mg Fe304, was heated to 1000 "C. Experimental results show that the reaction between the coal volatile and Fe 304 began at 700°C while the reaction between the coal char and Fe 304 occurred at 800°C and reached a peak at 900°C. Fe304 was fully reduced into FeO, while some FeO was further reduced to Fe. As the operation temperature rises, the reduction conversion rate increases. At the temperatures of 850°C, 900°C, and 950°C, the reduction conversion rates were 37.1 %, 46.5%, and 54.1% respectively. When the mass ratios of coal to Fe 304 were 5/95, 10/90, 15/85, and 20/80, the reduction conversion rates were 29.5%,40.8%,46.5%, and 46.6% respectively. With the increase of coal to Fe304 mass ratio, the conversion rate increases first and then changes no more. There exists an optimal coal to Fe 304 mass ratio.

Chemical Looping Hydrogen Generation over Ceria/Zirconia-Enhanced NiO–NiFe2O4 Oxygen Carrier

“…This also is consistent with the result of Fe 0.64 Ni 0.36 detected by XRD. The same phenomenon also appears in Figure 8d 4 oxidation, indicating that the small ZrO 2 particle showed better effect in protecting OC from sintering. In addition, due to the space limitation of ZrO 2 , the materials inside the enclosure can be better contacted and reacted.…”

“…Thus, in the CLHP system, pure hydrogen can be obtained after complete fuel combustion as R­(II). Moreover, the part of CLC has higher energy conversion efficiency than the integrated gasification combined cycle system, and chemical looping hydrogen (CLH) systems, which produce H 2 from syngas combined with integrated carbon capture, also show higher efficiency than the conventional H 2 generation technique The efficiency of the CLHP system mainly depends on the performance of the oxygen carrier.…”