(280g) The Status of Chemical Looping Processes Developed At the Ohio State University
AIChE Annual Meeting
Tuesday, October 18, 2011 - 2:42pm to 3:00pm
The chemical looping processes (CLP) have the potential to efficiently utilize the indigenously abundant carbonaceous fuels such as coal in an environment-friendly manner. The CLP utilize an oxygen carrier particle to indirectly convert carbonaceous fuels while capturing the CO2 byproduct for sequestration. This attractive incentive has resulted in global development of the chemical looping technology. At the Ohio State University, multiple chemical looping efforts ranging from pre-combustion to post-combustion of coal have been demonstrated under various scales. The iron-based CLP developed at the Ohio State University (OSU) presents a unique advantage compared to the other chemical looping technologies. The combination of a moving bed reactor system with the use of iron-based oxygen carrier results in the potential generation of high purity H2. This makes the iron-based CLP a fuel and product flexible technology. The OSU CLP can be classified into Syngas Chemical Looping (SCL) and Coal-Direct Chemical Looping (CDCL) technologies based on the fuel type handled in the looping system. The SCL process is tailor-made for complete conversion of any carbonaceous gaseous fuel like syngas and natural, with 100% in-situ CO2 capture. The process can be configured to generate H2, electricity or any combination thereof. It can also be incorporated into the Fischer-Tropsch process to enhance the efficiency and yield of coal to liquid fuels production. The process has been tested under a 25kWth sub-pilot scale continuous operation for more than 100 hours with current efforts focused on the scale up demonstration of the 250 kWth pilot SCL unit. The CDCL process involves the direct utilization of solid fuels, such as coal, biomass, etc., in the chemical looping reactor system with the same product flexibility as the SCL process. The direct introduction of solid fuel (coal) into the reactor system provides improved efficiency while presenting unique challenges. The CDCL system has been extensively demonstrated in the bench-scale (2.5 kWth) and the sub-pilot scale (25 kWth) unit is currently being constructed.
This presentation will discuss multiple aspects of the CLP being developed at OSU. The process reaction scheme of both the SCL and CDCL process will be presented in detail. This will be followed by the techno-economic evaluation of both the processes with a comparison to the conventional state-of-the-art processes. The results obtained in the SCL sub-pilot demonstration unit will be summarized followed by the preliminary CDCL testing results. The robust performance of the iron oxygen carrier particles synthesized at OSU will be highlighted with emphasis on future pathway for improvement. The current status of the SCL and CDCL processes will be addressed with special focus on the key results. Finally, the scale-up strategy of the processes for commercial use will also be highlighted.