The Phenomenon of Flame Jump in Counter-current Flame Propagation in Biomass Packed Beds - Experiments and Theory

• Published in: Combustion science and technology Vol. 194; no. 6; pp. 1199 - 1212
• Main Authors: V M, Jaganathan, Ambatipudi, Mani Kalyani, S, Varunkumar
• Format: Journal Article
• Language: English
• Published: New York Taylor & Francis 26.04.2022; Taylor & Francis Ltd
• Subjects: Biomass; Biomass burning; Carbon dioxide; Devolatilization; Equivalence ratio; Flame jump; Flame propagation; flame propagation regimes; Gasification; Hydrogen production; Mixtures; Oxidizing agents; packed bed; Packed beds; Parameter identification; Propagation; Theoretical analysis; Volatile compounds
• ISSN: 0010-2202; 1563-521X
• DOI: 10.1080/00102202.2020.1804886

In this paper the phenomenon of flame jump vis-a-vis steady propagation in biomass packed beds in counter-current mode is discussed. By analyzing the fuel flux and propagation rate data from experiments with a range of oxidizers, namely, air, O 2 -N 2 , O 2 -CO 2 , and O 2 -steam mixtures, parameter regimes of steady propagation, and flame jump are identified. A theoretical basis for this classification is developed by analyzing the thermo-chemical conversion of single particles subject to flow and thermal conditions in a packed bed. The ratio of the ignition ( ) to devolatilization ( ) times is shown to emerge as the controlling parameter in determining the flame propagation regimes. It is found from the theoretical analysis that steady propagation occurs for < 2 and transition to flame jump occurs if 2. Operational zones of a packed bed biomass system is mapped using the predicted ratio of as a function of volatiles-based equivalence ratio ( ). Implications of these results to practical ligno-cellulosic biomass combustion and gasification systems, especially using oxygen-steam mixtures for hydrogen generation, are brought out.