A study on combustion characteristics of dried sludge pellets by use of a pulverized coal combustion test furnace

Abstract

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 NOx conversion ratios (NOx concentration at the furnace outlet / NOx concentration when all the nitrogen in the fuel converts into NOx) 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.