Journal of the Japan Institute of Energy

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Two kinds of dried sludge pellets of municipal sewage sludge, produced by the Indirect Multi-Stage Tray Sludge Dryer Pelletier, were fired in a pulverized coal combustion test furnace (thermal input of fuel: 760 kW). Gas compositions and temperature at the furnace outlet and in the furnace were analyzed, and the unburned carbon in fly ash was also measured. The results are compared with those of a bituminous coal combustion test. The combustion efficiencies of the dried sludge pellets of municipal sewage sludge are higher than that of the bituminous coal. The NO_X conversion ratios (NO_X concentration at the furnace outlet / NO_X concentration when all the nitrogen in the fuel converts into NO_X) of the pellets are extremely lower than that of the bituminous coal. The temperature distributions of the pellets are different from that of the bituminous coal. The gas composition distributions are also different from that of the bituminous coal.

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An experimental study on the non-catalytic NO oxidation using methanol, ethanol, or acetaldehyde as an additive was performed, and the results were investigated by numerical analysis and sensitivity analysis using a chemical reaction model. It is found that the maximum NO oxidation efficiency when employing methanol is greater than 0.85, whereas the maximum using ethanol is approximately 0.6. Although it is known that methanol and ethanol have different oxidation reaction routes, non-catalytic NO oxidation may even be realized using the latter. Moreover, relative to utilizing alcohol, lower oxidation efficiency are observed using acetaldehyde. Thus, employing alcohols with ignition points above 600 K may be suitable for the non-catalytic NO oxidation.

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