Characteristics of stoichiometric CH4/O2/CO2 flame up to the pure oxygen condition. (1st February 2019)

• Record Type: Journal Article
• Authors: Li, Bo; Shi, Baolu; Chu, Qingzhao; Zhao, Xiaoyao; Li, Junwei; Wang, Ningfei
• Is Part Of: Energy. Volume 168(2019)
• Page Start: 151
• Page End: 159
• Publication Date: 2019-02-01
• Subjects: Oxy-fuel combustion -- Oxygen content -- Tubular combustion -- Combustion regimes; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2018.11.039
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: To pursue high efficiency in oxy-fuel combustion, usually a stoichiometric mixture with high oxygen content is preferred. However, the oxygen level in industrial operation is restricted by potential hazards of flame flash back, equipment erosion and combustion instability. In this study the stoichiometric CH4 /O2 /CO2 mixtures are tested in a rapidly mixed tubular flame combustor by varying the oxygen content from 0.21 to 1.0. Based on previous studies, the combustor is optimized to successfully achieve the steady tubular combustion up to the pure oxygen condition; the adiabatic flame temperature can vary between 1750 and 3050 K; in the CH4 /O2 tubular flame, the overall mole fraction of active radicals can reach 0.20, and the net heat release rate is much higher than that of CH4 /air flame. With three additional burners, this study systematically evaluates the influential factors such as oxygen content, inlet size, burner diameter and flow rate on the flame characteristics; furthermore, the dimensionless Damköhler number and Reynolds number are adopted to quantitatively identify different burning regimes through the Borghi diagram; the results provide a useful guide to the operation of oxy-fuel combustion up to the pure oxygen condition. Highlights: Steady stoichiometric CH4 /O2 /CO2 combustion is achieved up to pure oxygen condition. Flame structure, temperature, burning velocity, product and stability are examined. Burning regimes are identified by Borghi diagram of Damköhler and Reynolds numbers.