Emission factors for 19 polycyclic aromatic hydrocarbons were measured during wind tunnel simulations of open burning for agricultural and forest biomass fuels including cereal grasses, agricultural tree prunings, and fir and pine wood (slash). Yields of total PAH varied from 5 to 683 mg kg-1 depending principally on burning conditions and to a lesser extent on fuel type. Barley straw and wheat straw loaded at 400−500 g m-2 emitted much higher levels of PAH, including benzo[a]pyrene, than other cereal and wood fuel types burning under more robust conditions. As anticipated, total PAH emission rates increased with increasing particulate matter emission rates and with declining combustion efficiency.

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Gasification of four biomass feedstocks (leucaena, sawdust, bagasse, and banagrass) with significantly different fuel-bound nitrogen (FBN) content was investigated to determine the effects of operational parameters and nitrogen content of biomass on the partitioning of FBN among nitrogenous gas species. Experiments were performed using a bench-scale, indirectly heated, fluidized-bed gasifier. Data were obtained over a range of temperatures and equivalence ratios representative of commercial biomass gasification processes. An assay of all major nitrogenous components in the gasification products was performed for the first time, providing a clear accounting of the evolution of FBN. Important findings of this research include the following:(1) NH 3 and N 2 are the dominant species evolved from fuel nitrogen during biomass gasification; >90% of FBN in feedstock is converted to NH 3 and N 2 ; (2) relative levels of NH 3 and N 2 are determined by thermochemical reactions in the gasifier; these reactions are affected strongly by temperature; (3) N 2 appears to be primarily produced through the conversion of NH 3 in the gas phase; (4) the structural formula and content of fuel nitrogen in biomass feedstock significantly affect the formation and evolution of nitrogen species during biomass gasification.

Abstract. Particulate matter emitted from wind tunnel simulations of biomass burning for five herbaceous crop residues (rice, wheat and barley straws, corn stover, and sugar cane trash) and four wood fuels (walnut and almond prunings and ponderosa pine and Douglas fir slash) was collected and analyzed for mojor elements and water soluble species. Primary constituents of the particulate matter were C, K, C1, and S. Carbon accounted for roughly 50% of the herbaceous fuel PM and about 70% for the wood fuels. For the herbaceous fuels, particulate matter from rice straw in the size range below 10 gm aerodynamic diameter (PM10) had the highest concentrations of both K (24%) and C1, (17%) and barley straw PM10 contained the highest sulfur content (4%).•, •, and S were present in '•'• n•s of •'• wood c,,• ot ,-,•a .... a lc,,7o1• with maximum concentrations of 6.5% (almond prunings), 3% (walnut prunings), and 2% (almond prunings), respectively. Analysis of water soluble species indicated that ionic forms of K, C1, and S made up the majority of these elements from all fuels. Element balances showed K, C1, S, and N to have the highest recovery factors (fraction of fuel element found in the particulate matter) in the PM of the elements analyzed. In general, chlorine was the most efficiently recovered element for the herbaceous fuels (10 to 35%), whereas sulfur recovery was greatest for the wood fuels (25 •o 45%). Unique potassium to elemental carbon ratios of 0.20 and 0.95 were computed for particulate matter (PM10 K/C(e)) from herbaceous and wood fuels, respectively. Similarly, in the size class below 2.5 gm, high-temperature elemental carbon to bromine (PM2.5 C(eht)/Br) ratios of-7.5, 43, and 150 were found for the herbaceous fuels, orchard prunings, and forest slash, respectively. The molar ratios of particulate phase bromine to gas phase CO2 (PM10 Br/CO2) are of the same order of magnitude as gas phase CH3Br/CO2 reported by others.