Abstract
In the U.S. alone, approximately 200 million tons of dry cattle waste are being produced annually. Recently, cattle and poultry manure have been classified as biomass fuels and have been identified as sources of renewable energy. One of the processes for energy conversion of biomass fuels is thermochemical gasification. For the current study, a laboratory scale, 10 kW[th], fixed-bed gasifier (reactor internal diameter 0.15 m, reactor height 0.30 m) facility was built at the Texas A&M University Boiler Burner Laboratory, and was fired with a) coal, b) feedlot biomass (FB), c) chicken litter biomass (LB), d) high ash feedlot biomass (HFB), e) coal: FB blend (CFB), f) coal: LB blend (CLB), g) coal: HFB blend (CHFB), and h) LB: HFB blend (LHFB). The temperature profiles, and the gas species profile in the bed are measured and the species analyzed for heat contribution. The parametric studies include the effect of fuel particle size (average particle used were 0.52 mm and 9.5 mm), and the air flow rate (45 and 60 SCFH) on the gasification characteristics of the fuels. A summary of the results is as follows: The peak temperature in the bed was about 1500 K for coal (4.28 % ash), 1350 K for FB (14.83 % ash), and 1200 K for LB (43.85 % ash), correlating the decreased peak temperature with increased ash content. The devolatilization of coal, FB, and LB yielded the following: CH₄ (%): 2.5, 1.8, 1.0, CO (%): 27.9, 29.1, 29.1, H₂: 8.5, 8.0, 7.0. On an average, the heating value of the product gas leaving the gasifier was about 5.0 MJ/m³ for coal, 4.8 MJ/m³ for FB, and 4.5 MJ/m³ for LB. The gasification efficiency (45 SCFH) was the lowest for coal (37 %), followed by 39 % for FB, and 68.47 % for LB fuels. LB (18.9 % (Na₂O + K₂O) in ash) showed consistent bed agglomeration, while FB (7.03 %) showed a reduced tendency for agglomeration, and coal (1.98 %) exhibited no agglomeration in the bed. Based on the current gasification study FB is preferred compared to LB, since the former has a lesser tendency to agglomerate.
Priyadarsan, Soyuz (2002). Fixed bed gasification studies on coal-feedlot biomass and coal-chicken litter biomass under batch mode operation. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2002 -THESIS -P75.