Gravity-Based Percolation of Small Particles through an Assembly of Large Particles

The Chemical-Looping Gasification is one of several options being explored to design and operate a Chemical-Looping System using solid fuels (e.g. coal). There are many challenges for solid fuel chemical looping, such as the handling of the oxygen carrier, the continuous feeding of the solid fuel and its mixing with the oxygen carrier to maximize its conversion, and how to continuously remove of the solid wastes (e.g. ash) during the fuel consumption process to maintain efficient operations. One proposed configuration to address these challenges is a moving bed reducer (e.g. Stevens, Fan et. al., Velazquez-Vargas, Tong et. al.). The reactor consists of a slow downward moving bed composed of oxygen-carrier and larger solid fuel particles with a multiphase stream composed of gas and smaller particles moving through the pore network formed by these larger particles. The insight in the overall dynamics of this reactor configuration and its accurate prediction is of practical interest for the design and operation of these solid fuel-based moving bed reactors.

There are many interacting physical sub-processes within this system. In this work, we examine one relevant sub-processes: mono- and bi-disperse gravity-driven percolation of fine particles through a packed bed of larger particles. Using the results from extensive Discrete Element Method (DEM) simulations, we discuss percolation regimes through the analysis of the mean transit time and the radial variance of the positions of the percolating matter. The numerical results are also compared with experimental data (Lominé & Oger, 2006).

References

L. Velazquez-Vargas, “Final Report: Commercialization of an atmospheric iron-based CDCL process for power production. Phase I: Technoeconomic analysis”, DOE-FE009761 (2013).

https://www.osti.gov/scitech/servlets/purl/1222706/

L-S Fan., “Coal Direct Chemical Looping (CDCL) Retrofit to Pulverized Coal Power Plants for In-Situ CO2 Capture”, Project Review Meeting, DOE-NT0005289 (2014).

https://www.netl.doe.gov/publications/proceedings/10/co2capture/presentations/wednesday/Ray%20Kim-NT0005289.pdf

R. Stevens, R. Newby, D. Keairns, M. Woods, “Moving Bed Chemical Looping Combustion (MB-CLC) Reference Plant Design and Sensitivity Studies”, Clearwater Coal Conference (2016).

A. Tong, S. Bayham, M. V. Kathe, L. Zeng, S. Luo, L.-S. Fan. “Iron-based syngas chemical looping process and coal-direct chemical looping process development at Ohio State University”. Applied Energy 113, pp. 1836–1845 (2014)

F. Lominé, L. Oger. “Transport of small particles through a 3D packing of spheres: experimental and numerical approaches”. Journal of Statistical Mechanics: Theory and Experiment, pp. 1-13 (2006)