TASK 3.4--IMPACTS OF COFIRING BIOMASS WITH FOSSIL FUELS

摘要: With a major worldwide effort now ongoing to reduce greenhouse gas emissions, cofiring of renewable biomass fuels at conventional coal-fired utilities is seen as one the lower-cost options achieve such reductions. The Energy & Environmental Research Center has undertaken fundamental study address viability with coal in pulverized (pc)-fired boiler for power production. Wheat straw, alfalfa stems, and hybrid poplar were selected candidate materials blending 20 wt% level an Illinois bituminous Absaloka subbituminous coal. found be easily processed by shredding pulverizing size suitable pc bench-scale downfired furnace. A literature investigation was on mineral uptake storage plants considered order understand modes occurrence inorganic elements plant matter. Sixteen essential elements, C, H, O, N, P, K, Ca, Mg, S, Zn, Cu, Fe, Mn, B, Mo, Cl, are throughout plants. predominant K which function all cells will, therefore, evenly distributed nonreproductive, aerialmore » portions herbaceous biomass. Some constituents, e.g., organically associated incorporated into structure plant. Cell vacuoles repository excess ions Minerals deposited these ubiquitous organelles expected most leached from dry material. Other may not have specific functions within plant, but nevertheless absorbed fill need, silica. Na, nonessential, Their concentration will depend entirely extrinsic factors regulating their availability soil solution, i.e., moisture content. Similarly, Cl content determined less needs than solution; addition occurring naturally, present anion complement fertilizer applications. An analysis performed existing data switchgrass samples ten different farms south-central portion Iowa, goal determining correlations between elemental composition geographical seasonal changes so identify that influence important levels various chemical compounds differences related conditions. Combustion testing obtain deposits typical fouling slagging conditions well fly ash. Analysis methods using computer-controlled scanning electron microscopy fractionation applied determine association samples. Modified sample preparation techniques quantification procedures cluster developed characterize material Each types exhibited associations fuel Morphological analyses wheat straw show elongated 10-30-{micro}m amorphous silica particles or phytoliths structure. Alkali potassium, calcium, sodium bound dispersed organic materials. test results showed blends fed quite evenly, good burnout. Significant slag deposit formation observed 100% compared coals burned under similar Although growing rapidly, coal-biomass significantly weaker those coals. Fouling only slightly worse ash greatest similarity analyzed. high percentage both contained Si K. While significant component fuel, very little detected sample.« less