Characteristic Evaluation and Process Simulation of CuFe₂O₄ as Oxygen Carriers in Coal Chemical Looping Gasification

Chemical looping gasification (CLG) has been described as an innovative and low-cost gasification technology to convert carbonaceous fuels into synthesis gases. Oxygen carrier (OC) is the key to resolve the contradiction between rapid carbon conversion and appropriate partial oxidation of coal. At present, the solid fuel conversion in the CLG process is limited by an iron-based OC, and a copper-based carrier has difficulty in maintaining the reduction atmosphere. Hence, CuFe₂O₄ has been proposed as a high-performance OC because of its synergistic effect. The present study first conducted a characteristic evaluation on CuFe₂O₄, including the reducibility and oxygen release capacity. The results showed that the addition of copper made a great contribution to the reduction process, and the presence of ferrite better relieved the deep oxygen loss of CuFe₂O₄. The thermodynamic limitation and evolution behavior of CuFe₂O₄ in the reduction process were discussed for the simulation. An Aspen model of the CLG process with coal as the fuel and CuFe₂O₄ as the OC was then established and validated by the experimental data. By consideration of the high carbon conversion and high syngas productivity in the operation, an OC/fuel mass ratio of approximately 1.25-2.25 and a gasification temperature range of 800-900 °C were thought to be optimal in the coal CLG process.