Theoretical and Experimental Studies of Rice Husk Gasification Using Air as Gasifying Agent in a Downdraft Gasifier
Authors: Salisu J, Muhammad MB, Atta AY, Mukhtar B, Yusuf N, Waziri SM, Bugaje IM
Biomass gasification is a thermochemical process that converts biomass to a combination of gases known as syngas. It is considered to be a clean energy route and a way of reducing greenhouse gas emissions. Syngas has wide application in heating, power generation and synthesis of chemicals and liquid fuels. This paper reports a mathematical model formulation to predict rice husk gasification and experimental gasification of rice husk using air as gasifying agent. Theoretical rice husk gasification was done by inputting the composition of a characterized rice husk into set of mathematical equations derived using equilibrium approach and the resulting equations were solved using Newton Raphson method in MATLAB between temperatures of 500 and 1100 oC. Experimental rice husk gasification was conducted using a downdraft gasification system comprising of a gasifier as reactor, cyclone, filter, air blower and attached gas analyzer. Effect of varying air flow rates (6.4, 3.0 and 0.7 L/min) were studied; temperature, syngas composition and calorific value were monitored. The results of the model indicated an optimum temperature at 800 oC with syngas calorific value of 4.47 MJ/m3. The best experimental syngas composition recorded was at 6.4 L/min air flow. Root mean square error value of 7.58 was calculated when the model developed was validated with the best results obtained from the experiment. Performance analysis shows that for experimental gasification, the highest carbon conversion efficiency and cold gas efficiency were achieved at the highest air flow rate (6.4 L/min) as 21.27 and 12.55% respectively.
Affiliations: Department of Chemical Engineering, Ahmadu Bello University, Zaria, Nigeria.
Keywords: Gasifier, Rice Husk, Biomass, Gasification, Modelling
Published date: 2019/12/30