Chemical looping combustion and gasification - A novel technique to produce concentrated stream of hydrogen and carbon dioxide from victorian lignites

Chiranjib Saha, Ali Akhavan, Sankar Bhattacharya

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Abstract

Chemical-Looping combustion and gasification is a novel technique where an oxygen carrier is used to transfer oxygen from the combustion air to the fuel, thus avoiding direct contact between air and fuel. This technology is an alternative to conventional combustion and gasification where oxygen needs to be supplied from air or air separation plants which are energy intensive. This new methodology prevents CO 2 from being mixed with combustion gases. Chemical looping concept has been widely studied for combustion of natural gas; however its application to solid fuel, such as coal, is being studied only recently. From literature it is evident that limited number of studies has been performed on chemical looping using lignites. Victoria has large resources of lignites ( > 500 years at current consumption rate) and therefore there is a strong incentive for development of efficient technologies, such as chemical looping, for power generation from lignites. Oxide of metals such as Nickel, Copper, Cobalt, and Manganese are good oxygen carrier candidates and have been studied extensively to be used in chemical looping process. Iron oxide is an inexpensive mineral in Australia and when used in chemical looping, it is expected to generate concentrated stream of CO 2 and H 2 . However, much is unknown about the yield of products such as H 2 , CO 2 , CO, Char etc. from this process as a function of time, temperature, particle size and type of lignites. Present literature also lack information regarding the fate of the externally added Fe 2 O 3 particles through their interaction with the constituents of lignites and their prospects for regeneration. This paper explores the possibility of using lignite in chemical looping with iron oxide as oxygen carrier. The reduction and reoxidation properties of Fe 2 O 3 are investigated using thermogravimetric analyzer (TGA). Scanning electron microscopy (SEM) along with EDX of fresh solid reactants is compared with used reactants to understand the changes in surface morphology and mineral composition. Surface elemental information of agglomerates as a function of temperature and time are also being investigated. This paper presents preliminary results from this ongoing study.
Original languageEnglish
Title of host publication27th Annual International Pittsburgh Coal Conference 2010, PCC 2010
Pages457-467
Number of pages11
Volume1
Publication statusPublished - 1 Dec 2010

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