Date of Completion
Modeling, chemical looping combustion, optimization, fixed bed, dusty gas diffusion
George M. Bollas
Field of Study
Doctor of Philosophy
Combustion of hydrocarbon fuels using the concept of chemical-looping combustion (CLC) is a novel approach projected to have higher energy efficiency than conventional CO2 capture technologies. For CLC technologies to become commercially relevant, it is important to optimize the design of CLC reactor systems for high efficiencies for CO2capture and power generation. From an engineering point of view, CLC is a complex system with a large number of candidate materials and reactor configurations that need to be considered for process improvement. In this work, a model-based methodology was proposed as a formal framework to guide in developing novel technologies, using CLC as an exemplary case study. This framework deals with the development and validation of process models, optimization of a cyclic controls strategy for batch systems, and elimination process bottlenecks through the intensification of chemical reactors. As a first step, modelling and simulation was integrated with bench-scale CLC experiments to understand the phenomenological changes inside the CLC reactor and identify sources of model uncertainty. Optimal experimental design techniques were used to determine statistically-rich kinetic networks and parameters, in order to obtain kinetic models that are valid for prediction and extrapolation to large-scale systems. Optimization problems were formulated to maximize the efficiency of the CLC reactors with respect the cycle operation, to seamlessly integrate CLC into advanced power cycles. It was found that the process efficiency of conventional CLC reactor configurations was limited by an upper bound due to restrictions originating from poor gas/solid contact and low bed utilization. To improve upon the existing reactor designs, a novel reverse-flow reactor was proposed as a process intensification option for CLC. From a theoretical analysis, the reverse-flow process is shown to be a potentially disruptive technology, which offers the ability to reach higher plant efficiencies, while minimizing the process footprint. The feasibility of this structured methodology is demonstrated, as a means to enable faster deployment of novel technologies.
Han, Lu, "Dynamic Simulation, Optimization, and Control of Flexible Chemical-Looping Combustion Processes" (2016). Doctoral Dissertations. 1039.