To provide a water channel decompression structure capable of being installed at low cost and a bypass line installation method for hydroelectric power generation using the structure.
A part of headrace and discharge channel between which a Francis water turbine of an existing hydraulic power plant exists is used as a bypass channel of a new hydraulic power plant. A water turbine is removed except for a spiral casing 1 of the turbine. A decompression element is placed at the center part of the casing 1 left in the bypass water channel. The decompression element formed in cylindrical shape has a porous member 2 with multiple holes 2a through which water coming from upstream into the casing 1 passes to adjust a water pressure of downstream in the water channel to be lower than that of upstream to form a water channel decompression structure. Thus, a water channel decompression structure and a bypass line for hydraulic power generation can be installed at low cost by using the casing 1 of an used water turbine.
NAGASE ATSUSHI
NISHIKAWA HIROTOSHI
Higashio Masahiro
Takayoshi Tagawa