SAND SEDIMENTATION SEPARATION APPARATUS

摘要

Coarse sand grains and fine sand grains in a raw water are separately removed from the beginning and are efficiently separated from the raw water. Two sand sedimentation separation tanks (10) and (20) are disposed upstream and downstream, respectively, in the flow of a raw water. Each sand sedimentation separation tank has, in an upper part thereof, a separator (11) or (21) where a raw water is caused to flow through a spiral channel (13) or spiral channels (23A) and (23B) to thereby separate sand grains from the raw water by the action of centrifugal force and gravity. Each separation tank further has, in a lower part thereof, an accumulator (12) or (22) where the sand grains separated with the separator are settled and accumulated. The separator of the upstream-side sand sedimentation separation tank has a constitution in which coarse sand grains are separated by causing a raw water to flow through the spiral channel at a high velocity. The separator of the downstream-side sand sedimentation separation tank has a constitution in which fine sand grains are separated by causing the raw water to flow through the spiral channels at a lower velocity than in the separator of the upstream-side sand sedimentation separation tank.