Combustion of a Single Wood Log Under Furnace Conditions

Abstract

This paper presents the results of experimental combustion studies of large particle (>10 cm) thermally thick woody biomass under conditions representative of packed bed combustion. The combustion rate of thermally thick yellow poplar and paper birch tree segments (12 cm to 21 cm in diameter by 1.5 m long) in a typical combustion environment was measured in a special test furnace using load cells to measure mass versus time. Test conditions included a temperature range of 950{\textdegree}C to 1340{\textdegree}C and a variety of oxygen, carbon dioxide, and water vapor concentrations. Both green and dry woods were tested. The time to consume 90% of the mass of the wood ranged from 13 min to 55 min depending on wood and furnace conditions. The thickest char layer observed during these studies was 2 cm. A simple relationship for the buildup of the char layer within the range of conditions studied was developed. A numerical model to determine the combustion rate of single logs within the kiln, for the range of experimental values was developed using global reaction rates for combustion and gasification. Agreement between the numerical model and the experimental values is within 30% for nearly all of the 72 data points.