Reburning of Cattle Biomass with Coals for Emissions Control
H. Oh, K. Annamalai, J.M. Sweeten
Texas A&M University, US
Keywords: reburn, cattle biomass, NOx reduction, renewable engergy
Abstract:Biomass fuels can subdivided into two classes: agricultural (AgB) and Animal waste (AnB). The AnB includes cattle manure or cattle biomass (CB), Poultry Litter or poultry biomass (PB), Hog biomass (HB) etc. Since the chemical composition of AnB fuels are almost similar to the ration fed to animals except for N and P, the quality of fuels are similar to those of AgB on dry ash free basis(DAF). Cattle biomass (CB) has been proposed as a renewable, supplementary fuel for co-firing and reburning with coal. Particularly reburning CB with coals has the potential to emissions in coal-fired boilers as well as to reduce fuel costs, lower coal consumption, decrease nonrenewable CO2 emissions, and dispose of agricultural waste from large concentrated animal feeding operations (CAFOs). To investigate the emission reductions from combustion of CB, experiments were performed on a small-scale (30 kW or 100,000 BTU/h) boiler burner facility. The objective is to determine the optimum operating conditions for the best NOx reductions using CB as reburn fuels. The results show that dairy biomass (DB) and feedlot biomass (FB) can be used very effective reburn fuels for the NOx emission control in coal-fired power plants. The % of NOx reductions increased with an increase of the CB proportion in reburn fuels and increase of equivalence ratio (ER) in the reburn zone and resulted in significant reductions of NOx. In the presence of heat exchangers (HEXs) in the boiler, higher NOx reductions were observed compared to the cases without HEXs. These higher reductions were probably caused by lower gas temperatures and catalytic effects of ash on HEXs.