A numerical study of accelerated moderate or intense low-oxygen dilution (MILD) combustion stability for methane in a lab-scale furnace by off-stoichiometric combustion technology
Autor: | Mengqian Xie, Yaojie Tu, Fangqin Dai |
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Rok vydání: | 2021 |
Předmět: |
Environmental Engineering
Materials science General Chemical Engineering Mixing (process engineering) 02 engineering and technology General Chemistry 021001 nanoscience & nanotechnology Combustion Biochemistry Instability Methane law.invention Dilution Ignition system chemistry.chemical_compound 020401 chemical engineering chemistry Chemical engineering law Combustor 0204 chemical engineering 0210 nano-technology Stoichiometry |
Zdroj: | Chinese Journal of Chemical Engineering. 32:108-118 |
ISSN: | 1004-9541 |
Popis: | Moderate or intense low-oxygen dilution (MILD) combustion has become a promising low-NOX emission technology, while the delayed mixing of reactants and slower oxidation rate could potentially cause ignition instability in some scenarios. This paper proposes a new idea for enhancing the ignition stability for methane MILD combustion by combining with off-stoichiometric combustion (OSC), and its performances have been numerically assessed through a comparison against the original MILD combustion burner. The results reveal although non-premixed pattern has the lowest NO emission, it suffers from a larger liftoff distance, thus less ignition stability. Contrarily, both partially-premixed and fully premixed patterns exhibit excellent ignition stability. Among the considered OSC conditions, the pattern of Inner ultra-rich and Outer lean produces the lowest NO emission while maintains a high ignition stability. Furthermore, the enhancement of the combustion stability by implementing OSC to the original MILD combustion burner is shown by comparing the operational range of furnace wall temperature (Tf), CO and NO emissions, as well as the evolution of chemical flame. The comparison reveals that OSC can extend the lowest operational Tf from 900 K to 800 K. More importantly, OSC can significantly improve the ignition stability in the whole range of Tf as compared to the original MILD combustion burner. |
Databáze: | OpenAIRE |
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