(197f) Modeling and Sensitivity Analysis of the Chemical Looping Combustion Process

Chemical looping is believed to a promising technology in clean combustion of gas or solid fuels for future power generation. In this process, oxygen required for combusting the fuel is provided through metal oxides rather than using air/oxygen. This prevents the production of pollutants like oxides of nitrogen as there is no nitrogen present in the feed. In addition, it has been proved that almost pure carbon dioxide can be produced as a result of this process which makes it easy for carbon sequestration. Noteworthy experimental works have been carried out in the past few years in determining the better metal oxide for these systems. However, the characteristics of metal oxides vary quite significantly with respect to fuel types. Thus, a universal metal oxide which suits for all kinds of fuel is yet to be determined. Therefore, devising a mathematical model to study the effectiveness of various important physical and operating parameters will be beneficial.

The process consists of two fluidized bed reactors connected through loop seals to maintain the pressure drop in the reactors. The inflow and outflow of the solid metal oxide and the fuel should be monitored appropriately for enhanced performance. The process is still at the nascent level and being controlled manually or by simple control algorithms. Once commercialized, there will be a definite need of advanced control strategies for controlled power output. Thus, in this study, we focus on developing a model for the entire CLC system with a view point of determining the optimal operating conditions and the sensitivity of important operating parameters. The model is based on system invariants under thermodynamic equilibrium coupled with the shrinking core mechanism to represent the gas-solid reactions. The model results are validated based on the experimental data available in the literature. To the authors' knowledge, this work is the first in proposing a control oriented model for the CLC system.

Keywords: Modeling, thermodynamic equilibrium, invariants, chemical looping combustion, control.