Experiments and attempts for practical use of the fluidized bed combustion, which has many advantages such as fuel flexibility, improved heat transfer, less maintenance cost, environmentally clean combustion, etc., are being world-widely carried out.
In the land service field, a fluidized bed combustion boiler is already in the process of being put to practical use, but in the marine service field, there is nothing but a few papers on a fundamental study and application of this boiler to a marine propulsion plant.
We made an experimental research of fluidized bed combustion for its marine use to cope with the recent trend to using low quality fuels such as coal and heavier fuel oil.
In the experiments, we used a 500 mm^_??_ vertical furnace and a 500 mm^_??_ inclined furnace adjustable in angles (0°, 10°, 15°and 22.5°) as test furnace, coal from Australia for test fuel, and silica sand for bed material, and we found relation for marine use between combustion factors (bed temperature, heat release, combustion air ratio, bed height, free board height in furnace) and combustion efficiency, change of bed temperature after coal feed cut, relation between ash recycle ratio and combustion efficiency, relation between furnace inclined angle and combustion efficiency, and measures to prevent unfluidized bed caused by inclined furnace.
On the basis of this research, we developed a marine fluidized bed combustion boiler and a marine propulsion plant, “Kawasaki-UNI Plant”, with the marine fluidized bed combustion boiler and a repeat steam turbine.
We will report about these developments on other papers.