Feasibility of Efficient Pyrolysis of Wood Chips and its Product Yield in Developing Countries

Abstract

This paper is about the feasibility of combustibles gases like methane, ethane and carbon monoxide production from wood pyrolysis. This first laboratory experimental stage objective was to see what products can be obtained from wood pyrolysis in absence of oxygen and presence of nitrogen. The effect of temperature on the product yields was investigated. Products were characterized using gas-chromatography.  We found that products of wood pyrolysis for temperatures of 700, 800, 900, 1000 and 1100°C were char, CO2 and combustibles gases like CH4, C2H2, CO and tar. NH3 was not found in the produced gases. In our study, condensable gases were not recovered and quantified. A gas condenser would have been necessary inserted for this purpose at the outlet of the pyrolysis reactor before routing the gases to the mass spetrograph. This study show that char production decrease from 17.08% at 700°C on the weight basis to 12.95% at 1100°C. Gases and tar production decrease, going from 82.92% at 700 °C on the weight basis to 87.05% at 1100°C. Carbone dioxide production also increase with temperature. It is the biggest part of produced gases of the wood pyrolysis gases representing an average weight proportion of 6.99% of the initial wood. Carbone monoxide yield is almost constant, around 1.6% at 800, 900 and 1000°C thought its yield at 700°C was found slightly higher accounting for 2.29% weight of the initial wood. Ethylene (C2H4) is only produced in small amount compared to others combustibles gases like methane and carbon monoxide. Its proportion which was observed almost constant, around 0.14% on the weight basis in respect to the initial wood chips weight from 700 to 900°C dropped to 0.02% at 1000°C. Methane (CH4) is produced in weight basis proportions of 2.55% which remain almost constant from 700 to 1000°C.