Characterization of natural copper ore as oxygen carrier in chemical-looping with oxygen uncoupling of anthracite

Chemical-looping with oxygen uncoupling (CLOU) provides a novel route for CO2 capture with low energy penalty. In this paper, natural copper ore, known for its low cost and abundant supply, was examined as an oxygen carrier material for CLOU in a batch fluidized-bed reactor. The relations between oxygen release/uptake rates and reactor temperatures were first explored. It was found as a general trend that both the oxygen release and uptake rates increase with the reactor temperature. The CLOU thermo-chemical characteristics were further investigated comprehensively using a typical Chinese anthracite (GaoPing coal) as fuel. The effects of reactor temperature, superficial fluidization velocity, oxygen carrier to fuel ratio, coal particle size, and steam content in fluidization gas on carbon conversion rate, coal combustion efficiency, and gas yields were investigated. It was found that the following factors would lead to a higher carbon conversion rate: a higher reactor temperature, smaller superficial fluidization velocity, smaller coal particle size, larger ratio of oxygen carrier to fuel, and higher steam volume concentration in the fluidization gas. High combustion efficiency above 96% and CO2 yield above 0.95 were attained in these tests. The copper ore particles showed only slight agglomeration and sintering in the long-term operation. (C) 2014 Elsevier Ltd. All rights reserved.