(16c) An Iron-Based Chemical Looping Coal Combustion Island

Coal is a carbon intensive energy source. Almost a third of the anthropogenic CO2 emissions are produced by coal-fired power plants, which produce more than 50% of the electricity generated in the US and about 40% of the electricity generated worldwide [1]. Among them, the pulverized coal-based power plants account for more than 90% of the electricity generated from coal [2]. Nowadays, there is both a growing concern about the effect of the greenhouse gases into the global climate and, a need to improve the efficiency of power plants. Coal Chemical Looping Combustion (CLC) is a promising technology to address these issues.

CLC is a two step process that provides inherent separation of carbon dioxide by avoiding direct contact between air and fuel. It integrates the combustion, the CO2 separation, and the water gas shift reaction into the chemical loop. An oxygen carrier, which transports oxygen and energy, circulates between an air reactor and a fuel reactor. In the air reactor, the oxygen carrier is oxidized with air while it provides the oxygen and energy for combustion in the fuel reactor. Generally, the oxidation of oxygen carrier is exothermic while its reduction is endothermic. In the fuel reactor, the fuel is never mixed with air so that almost pure CO2 is produced which may be compressed for sequestration.

At NETL we are working to model and simulate a CLC island that may be used for existing pulverized coal-based power plants. The aim is to develop plants with zero CO2 emissions. In this work we provide an optimized design of an iron-based CLC island. An Illinois No. 6 coal was used.

References: [1] U.S. Department of Energy, Annual Energy Outlook 2008, revised to Include the Impact of H.R. 6, ?Energy Independence and Security Act of 2007? Enacted in December 2007. DOE Energy Information Administration, Washington, DC, Report #: DOE/EIA-0383, 2008. [2] B. G. Miller, Coal Energy Systems, Elsevier, Amsterdam, Boston, 2005. [3] J. N. Armor, Catal. Lett., Vol. 114, 115?121, 2007. [4] F. Li and L. Fan, Clean coal conversion processes ? progress and challenges, Energy Environ. Sci., Vol. 1, 248?267, 2008.