Abstract
Carbon capture is essential to enable the use of fossil fuels while reducing the emissions of CO 2 into the atmosphere. Among the methods of CO 2 capture and storage, oxyfuel technology provides a promising option for power and steam generation systems. In this technology, the fuel is burned in pure oxygen instead of air, and the flue gas consists primarily of CO 2 and H 2O that can be easily separated via condensation. In order to moderate the furnace temperature in the absence of N 2, a fraction of the flue gas is recycled in the combustion chamber. In this work, the characteristics of oxyfuel combustion are compared to those of air-fuel combustion in a typical natural gas fired package boiler and the results can be applied to large boilers such as industrial and utility boilers. The percentages of recycled CO 2 considered in this study are 83.8% and 77% by mass. The first corresponds to 21% O 2 and the second corresponds to 29% O 2 by volume. Validations for both oxyfuel combustion and air-fuel combustion are conducted through comparison with the available experimental data. Results indicate that the temperature levels are reduced in oxyfuel combustion. As the percentage of recirculated CO 2 is increased, the temperature levels are greatly reduced. We found that the fuel and oxygen consumption rates are slower in oxyfuel combustion relative to air-fuel combustion. Heat transfer from the burnt gases to the water jacket along the different surfaces of the furnace is calculated. It is shown that the energy absorbed is much higher in the case of air-fuel combustion along all surfaces except for the end part of the furnace close to the furnace rear wall. The heat transfer in the return chamber (tube bank) was also calculated and the results indicated higher heat transfer in the oxyfuel case in comparison with the air fuel case as a result of ignition delay in the vicinity of the furnace entrance region.
Original language | English |
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Pages (from-to) | 152-165 |
Number of pages | 14 |
Journal | Computers and Fluids |
Volume | 56 |
DOIs | |
State | Published - 15 Mar 2012 |
Bibliographical note
Funding Information:The financial support of KFUPM under the KFUPM-MIT collaboration program during the course of this work is greatly appreciated. The support and collaboration of MIT mechanical engineering department is also appreciated.
Keywords
- Air-fuel combustion
- Computational fluid dynamics
- Oxyfuel combustion
- Water tube boilers
ASJC Scopus subject areas
- General Computer Science
- General Engineering