Abstract
A new type of sewage sludge incinerator, which combines a pressurized fluidized bed combustor and a turbocharger driven by flue gas, was proposed. We constructed a demonstration plant (4.32 t/d scale) at a sewage works in Oshamanbe Cho in Hokkaido. The objectives of this study were combustion characteristics of de-watered sludge in this plant. Additionally, the characteristics between our new plant and a conventional one were compared using the experimental results. As the results, CO NOx, and N2O emissions were SUBstantially reduced by the pressurization. N2O emission could be controlled by the freeboard temperature in spite of the high nitrogen content of the fuel and the pressurized conditions. In particular, N2O emission of the new plant was less half of that of the conventional plant. It is thought that N2O was decomposed at a local high temperature place in the freeboard. This phenomenon was verified qualitatively by investigating the chemical reaction rates. Therefore, our new fluidized bed incinerator with the turbocharger had a low environmental impact.
