Effect of oxygen addition in steam gasification of chicken manure

Abstract

The continued increase in the production scale of chicken industry have led to increased use of chicken manure as fertilizers or landfill disposal which leads to land and water pollution by eutrophication from landfills. Thus, although chicken manure is rich in ash and moisture content, thermochemical waste to energy techniques such as gasification of chicken manure makes it an efficient alternative energy source with clean waste management. The role of oxygen addition to steam gasification of chicken manure at different concentrations was examined and evolutionary behavior of the gases evolved with time were analyzed using gas chromatography. Isothermal conditions were maintained in a semi-batch reactor at a temperature of 1173K while the oxygen concentration was increased from 0% to 12% (dry basis). From the oxygen concentrations examined, the addition of oxygen decreased the reaction duration by 50% while improving the syngas characteristics and energy yield on short periods. The reduction in energy yield was limited to minimal amounts that varied from 4% to 15% with reduction directly proportional to oxygen content in the gasifying agent. Accumulative yield of carbon monoxide was maximum for oxygen concentration of 9% (dry basis) above which extra oxygen concentration caused further oxidation of the syngas components to decrease the energy content of syngas yield. The results revealed reduction in net energy requirements by decreasing the reaction time by up to 70% (for oxygen content of 12%) with minimal reduction in energy content from syngas yield and improved carbon conversion. These results provide improved design strategies for better waste to energy technique by addition of oxygen to steam during gasification of chicken manure.