- Title
- Thermogravimetric analysis of Ni0/Si0₂ oxygen carriers under CO/air environment for chemical looping combustion
- Creator
- Song, Hui; Shah, Kalpit; Doroodchi, Elham; Moghtaderi, Behdad
- Relation
- 11th Australian Combustion Symposium. Proceedings of the 11th Australian Combustion Symposium (Shoal Bay, N.S.W. 29 November-1 December, 2011) p. 223-226
- Relation
- http://www.anz-combustioninstitute.org
- Publisher
- The Combustion Institute: Australian and New Zealand Section
- Resource Type
- conference paper
- Date
- 2011
- Description
- Chemical looping combustion using coal offers several advantages such as higher net efficiency and in situ CO₂ capture during combustion process. However, direct utilization of coal is confronted with many challenges, in particular, the separation of the solids including coal ash and oxygen carriers. To avoid this, one of the most feasible ways is to use the product gas. ie. syngas, from coal gasification in chemical looping combustion. Looking to the reactivity difference between H₂ and CO in syngas during combustion, reactivity analysis of NiO/SiO₂ oxygen carriers have been investigated under alternating reduction (CO) and oxidation (Air) environment using thermogravimetric analyser (TGA) in the current work. The experimental matrix was designed based on two variables ie. temperature (ranging from 500⁰C to 950⁰C) and reducing agent ie. carbon monoxide (CO) - 5~70 vol%. A temperature dependent redox cycle was observed. The conversion rate and extent were observed to be higher with increase in temperature except for the experiment conducted at highest temperature 950⁰C where a lower reaction rate was observed with increased extent of conversion. This observation challenges some of the recent observations reported in the literature about related to the impact of nickel silicate formation and suggests that nickel silicate formation may not be entirely responsible for the drop in the conversion rate under CO reducing environments. Furthermore, kinetics of NiO/SiO₂ is determined using shrinking core model for reacting particles with spherical grain geometry. The values of activation energy E, reaction order n and pre-exponential factor k are found to be 24 kJ/mol, 0.85 and 0.095 mol⁻ⁿm³ⁿs⁻¹, respectively.
- Subject
- chemical looping combustion; reduction kinetics; oxygen carriers; carbon monoxide
- Identifier
- http://hdl.handle.net/1959.13/1055153
- Identifier
- uon:15846
- Identifier
- ISSN:1839-8170
- Language
- eng
- Full Text
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