Frazil Ice Blockage of Intake Trash Racks

摘要

Operating water intakes in lakes and rivers in northern regions is complicated bythe presence of ice. One of the most difficult problems is the accumulation of frazil ice on the intake trash rack, which can completely block the trash rack and rapidly and unexpectedly shut down the intake facility. In extreme cases the blockage can cause the intake trash rack to collapse. Blockages of intake trash racks occur sporadically, most often at night, in cold weather and always underwater. As a result, opportunities for observation and measurement are limited. This report discusses the following topics: The blockage process in rivers and in lakes; Coping with frazil blockage; Suppressing frazil production by using heat; Mechanical removal; Back flushing, Vibration; Blasting; Removal of trash racks; and Operating under frazil conditions.