Formation of multiple combustion fronts in an imbert downdraft gasification reactor

¹ School of International and Interdisciplinary Engineering Programs, School of Engineering, King Mongkut’s Institute of Technology Ladkrabang, 1 Soi Chalong Krung 1, Chalong Krung Road, Ladkrabang Bangkok, 10520, Thailand
² Department of Mechanical Engineering, Faculty of Engineering and Technology, Mahanakorn University of Technology 140 Cheum-Sampan Road, Nong-Chok, Bangkok 10530, Thailand
³ Department of Teacher Training in Mechanical Engineering,King Mongkut’s University of Technology North Bangkok, 1518 Phacharat 1 Road., Bang Sue, Bangkok 10800, Thailand

^* Corresponding author: kasemsilo@kmutnb.ac.th

Abstract

The experimental study of downdraft gasification was performed in this paper. The operation which led to the formation of the second combustion front was pointed out. In this situation, both combustion fronts will lose their intensity and finally be extinguished. The operation was unintentionally stopped. It was revealed that the combustion front propagated upward in the reactor after starting the test. While it was about to reach the air inlet nozzle, the second combustion front was detected by an abrupt temperature rise of the thermocouple above the air supply nozzle. After the formation of the second combustion front, both fronts started to lose their intensity which indicated by the decrease in temperature corresponding with their locations. It was possible that the second combustion front would dilute the oxygen concentration supplied to the first combustion front. The decreasing temperature of the first combustion front reduced the heat transfer rate to the second combustion front. Finally, both combustion fronts were extinguished. The operation was unintentionally stopped.