Assessment of technological solutions for improving chemical looping combustion of solid fuels with CO2 capture

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 233; pp. 56 - 69
• Main Authors: Gayán, P., Abad, A., de Diego, L.F., García-Labiano, F., Adánez, J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-11-2013
• Subjects: Carbon; Carbon capture and storage; Carbon dioxide; chemical engineering; Chemical-looping combustion; CO2 capture; Coal; Combustion; energy; Fuels; gases; gasification; Mathematical models; Optimisation; oxygen; Reactors; Simulation; simulation models; streams; Strippers; Chemical-looping combustion; CO2 capture; Simulation; Optimisation; Coal
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2013.08.004

New arrangement proposed for the iG-CLC process. [Display omitted]
•Several technological options to improve the performance of iG-CLC are analysed.•A mathematical model is developed to evaluate the performance of each option.•The use of a secondary fuel reactor increases the potential to reduce the oxygen demand.•A new iG-CLC configuration is proposed which minimises oxygen demand.
The chemical looping combustion of solid fuels by in situ gasification (iG-CLC) has great potential to reduce the economical and energetic cost of CO2 capture for generating energy from coal. Previous studies have highlighted that a high CO2 capture rate can be reached, but incomplete combustion is predicted by theoretical models or obtained during experimental work. In this paper, a mathematical model for the fuel reactor and carbon stripper, validated through experimental results, is adapted to evaluate the relevance of several technological improvements in order to increase the combustion efficiency of the iG-CLC process. The technological options evaluated include increasing the gas–solid contact in the fuel reactor, incorporating a secondary fuel reactor, re-circulating exhaust gases to the fuel reactor or the carbon stripper, or feeding coal into the carbon stripper instead in the fuel reactor. Model simulations showed that the use of a secondary fuel reactor has the major impact by reducing the unburnt compounds in the CO2 stream. The origin of the unburnt compounds is determined from a thorough analysis of the results obtained during the evaluation of these technological options. Thus, a new arrangement of the iG-CLC reactors is proposed, one which would minimise the presence of unburnt compounds. In this concept, exhaust gases from the fuel reactor are sent to the carbon stripper. The oxygen demand for this concept is predicted to be ΩT=0.9%.