Fuel reactor model validation: Assessment of the key parameters affecting the chemical-looping combustion of coal

Artikel i vetenskaplig tidskrift, 2013

The success of a Chemical Looping Combustion (CLC) system for coal combustion is greatly affected by the performance of the fuel reactor. When coal is gasified in situ in the fuel reactor, several parameters affect the coal conversion, and hence the capture and combustion efficiencies. In this paper, a mathematical model for the fuel reactor is validated against experimental results obtained in a 100 kW(th) CLC unit when reactor temperature, solids circulation flow rate or solids inventory are varied. This is the first time that a mathematical model for Chemical Looping Combustion of coal with in situ gasification (iG-CLC) has been validated against experimental results obtained in a continuously operated unit. The validated model can be used to evaluate the relevance of operating conditions on process efficiency. Model simulations showed that the reactor temperature, the solids circulation flow rate and the solids inventory were the most relevant operating conditions affecting the oxygen demand. However, high values of the solids circulation flow rate must be prevented because they cause a decrease in the CO2 capture. The high values of CO2 capture efficiency obtained were due to the highly efficient carbon stripper. The validated model is a helpful tool in designing the fuel reactor to optimize the CLC process. A CO2 capture efficiency of eta(CC) = 98.5% and a total oxygen demand of Omega(T) = 9.6% is predicted, operating at 1000 C and 1500 kg/MWth in the fuel reactor.