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Abstract
Quite some studies have been conducted in order to implement oxy-fuel combustion with flue gas recycle in conventional utility boilers as an effective effort of carbon capture and storage. However, combustion under oxy-fuel conditions is significantly different from conventional air-fuel firing, among which radiative heat transfer under oxy-fuel conditions is one of the fundamental issues. This paper demonstrates the nongray-gas effects in modeling of large-scale oxy-fuel combustion processes. Oxy-fuel combustion of natural gas in a large-scale utility boiler is numerically investigated, in which a recently refined weighted-sum-of-gray-gases model (WSGGM) applicable to oxy-fuel conditions is used to perform non-gray and gray calculations, respectively, and a widely used air-fuel WSGGM is also employed for gray calculation. This makes the only difference among the different computational cases. The simulation results show that the gray and non-gray calculations of the same oxy-fuel WSGGM make distinctly different predictions in the wall radiative heat transfer, incident radiative flux, radiative source, gas temperature and species profiles. In relative to the non-gray implementation, the gray calculation of the oxy-fuel WSGGM remarkably over-predicts the radiative heat transfer to the furnace walls and under-predicts the gas temperature at the furnace exit plane, which also result in a higher incomplete combustion in the gray calculation. Moreover, the gray and non-gray calculations of the same WSGGM make much more pronounced difference in the results than the gray implementation of different WSGGMs does (i.e., the oxy-fuel and air-fuel WSGGMs). Even though particle radiation also has an important impact and will compromise the demonstrated nongray-gas effects to some extent in large-scale oxy-coal combustion, the non-gray formulation of an oxy-fuel WSGGM is still highly recommended for a reliable oxy-fuel combustion modeling.
Original language | English |
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Journal | Energy & Fuels |
Volume | 26 |
Issue number | 6 |
Pages (from-to) | 3349-3356 |
Number of pages | 8 |
ISSN | 0887-0624 |
DOIs | |
Publication status | Published - 2012 |
Keywords
- Oxy-fuel combustion
- Radiative heat transfer
- Nongray-gas effects
- WSGGM
- CFD
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Dive into the research topics of 'Nongray-gas Effects in Modeling of Large-scale Oxy-fuel Combustion Processes'. Together they form a unique fingerprint.Projects
- 1 Finished
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OxyNG: Advanced modeling of oxy-fuel combustion of natural gas (ForskEL 10256)
01/05/2009 → 30/04/2011
Project: Research