(571d) Insights from Thermodynamic System Analysis of Thermochemical Solids Looping Systems for Reforming and Combustion Applications

Authors: 
Kathe, M., The Ohio State University
Sandvik, P., The Ohio State University
Wang, W. K., The Ohio State University
Kong, F., The Ohio State University
Fan, L. S., The Ohio State University
The iron-based moving bed based solids chemical looping technology developed at OSU is a versatile technology platform that can be used for various energy conversion applications. The technology platform has been adopted for gasification and combustion applications with system analysis showing efficiency and cost benefits. This talk will present two iron-based chemical looping case studies, wherein the system analysis provide insights into tradeoffs associated with maximizing the energy and product efficiency of a system. In the first case study, a three reactor chemical looping system for converting methane to hydrogen will be considered. This analysis is based on examining the thermodynamic limits for product formation, using mass balances and Gibbs Free Energy minimization. The system is designed to maximize H2 production from methane, while transferring energy between three chemical looping reactors. A surprising insight that is obtained from this analysis is that the system operating conditions for maximum H2 production may not always satisfy the energy balances associated with solids circulation. This case study will include results that discuss the trade-offs associated with maximizing H2 production as a function of several independent design variables like solids circulation, pre-heat temperatures, amount of inert solids and temperature swings associated with solids flow through the three reactor systems. In the second case study, a two reactor chemical looping system that produces syngas at high pressure will be evaluated. This system analysis provides a different tradeoff scenario, wherein high syngas yields may not always correspond to high methane conversions. Overall, for both the case studies an interplay of various independent parameters are leveraged to design looping systems that provide advantages over conventional methods. The results of both these studies will be used to draw holistic conclusions on thermodynamic process analysis of thermochemical solids looping systems.