To improve desulfurization characteristics by using limestone having a certain Ca content or above, a single crystal grain size in a specified range, a certain water absorption or above and a grain size in a specified range as a limestone fluid medium useful as a fluid medium for a fluidized bed combustion electricity generating system in coal burning thermal-power generation.
Limestone having ≥40 wt.% (expressed in terms of CaO) Ca content, 0.05-0.5 mm single crystal grain size, ≤3 wt.% water absorption and 0.1-10 mm grain size is used as a fluid medium and preferably 0.5-5.0 wt.% MgO is further incorporated. When cracks are present in the fluid medium, air confined in the medium expands at the time of heating to break and powder the medium and the medium cannot be reutilized. In order to prevent the breaking and powdering, the medium preferably has 0.05-0.5 mm single crystal grain size and ≤3 wt.% water absorption. A method for using the limestone fluid medium is not particularly limited and the conventional operation conditions of a fluidized bed can be adopted.
IZUMI KAZUSHI
NAKAMURA KAZUFUMI
MATSUMOTO TADASHI
NANBU MASAMITSU
BETSUPU MICHITOMO
