Co-gasification of blended coal with feedlot and chicken litter biomass

Intensive animal feeding operations create large amounts of animal waste that must be safely disposed to avoid environmental degradation. Improper disposal leads to contamination of water supplies and poses serious health risks to humans. In this paper, fixed-bed gasification has been described as a technology for utilizing animal waste as a source of renewable energy, which can reduce its disposal problems and associated pollution issues. Fixed-bed co-gasification studies on coal and animal waste-based fuels like feedlot biomass (cattle manure), and chicken litter biomass have been experimentally investigated under batch mode operation. The average oxidation-front and gasification-front propagation velocity, spatial temperature profiles, and product gas composition have been measured for coal and the blended fuels at two different airflow rates: 1.48 and 1.97 kg/h (1.28 and 1.70 m(3)/h), and two different fuel particle sizes: 9.4 (+/- 3.1), and 5.15 (+/- 1.15) mm. The results suggest that the average oxidation-front propagation velocity is primarily dependent on the airflow rate and ash content of the gasified fuel. Using phenomenological analysis, the average oxidation-front propagation velocity is correlated with a dimensionless group involving the fuel properties and airflow rate through the gasifier. The typical molar composition of the product gas is 27-30% CO, 7-10% H-2, 1-3% CH4, 2-6% CO2, and 51-63% N-2 (dry basis), which is almost insensitive to the fuel particle size and airflow rate. The heating value of the product gas mixture varies between 4.5 and 5.12 MJ/kg (dry basis). (c) 2004 The Combustion Institute. Published by Elsevier Inc. All rights reserved.