Spray-Drying-Granulated Composite Oxygen Carrier Using Fine Cooper Ore and Hematite Powders as Raw Materials

Abstract

The semi-industrial demonstration of chemical looping combustor has been achieved. Consequently, the industrial-scale production of economical oxygen carrier has emerged as one key issue. In this work, a series of low-cost copper-iron oxygen carriers (OC) have been successfully prepared by an industrial via spray dryer. Hematite and copper ores are used as raw materials of active compositions of OC, as well as montmorillonite or kaolin as inert binder. It is found that the addition of montmorillonite in the OC enhanced the reactivity during 100 cycles of H2-fuelled chemical looping combustion (CLC) in a thermogravimetric analyzer. By comprehensively considering the oxygen transport capacity and redox rates, the optimal mass fraction of montmorillonite is 10 wt%. Subsequently, the CLC performance of the resultant CuFe10M OC (with 10 wt.% montmorillonite) is evaluated in a batch fluidized bed reactor using Shenhua bituminous coal as fuel. During the 100 redox cycles, the carbon conversion rate of coal, oxygen transfer rate of OC, and CO2 peak value exhibited an initial increase (within 1~70 cycles) and followed by a subsequent decrease (71-100 cycles), which correlated with the evolution of BET surface areas of OC. However, the gas yields and combustion efficiency are relatively stable throughout the entire experiment. When finishing the 100 cycles of coal-fueled CLC, slight sintering is observed on the surface of used OC. Nonetheless, the Fe, Cu, and Si elements in the OC particles remain uniformly distributed.

Keywords: chemical looping combustion, Oxygen carrier, Spray-drying granulation, Industrial scale