Author(s): Brian Morse; Tung-Thanh Quach
Linked Author(s):
Keywords: No Keywords
Abstract: For a 3.5-km open reach of river upstream of a hydro dam, we estimate daily heat loss to the atmosphere during typical winter conditions to be 4000 MWh, or 166 MW (thermal). This heat loss results in frasil ice formation equivalent to 47000 cubic meters of ice per day. This ice continues downstream and flows under a fixed cover upstream of the dam causing a hanging dam and potential flooding. In the past, fortunately, groundwater and wastewater coming from multiple sewers emptying into the river offset the heat loss. However, in a concerted effort to clean up the aquatic environment, the local government recently diverted these contaminated waters totemperature of 9oC resulted in loss of at least 124 MW. So after the treatment facility was built in 1995, frasil ice production in the reach quadrupled due to heat loss from42 MW to 166 MW. To prevent upstream flooding, the hydroelectric facility is forced to perform aggressive ice interventions under very stressful circumstances. It also results in a loss of electrical power (due to the necessary flow diversion and the loss in head due to ice accumulation in the reach downstream of the dam). In this paper, we discuss the effectiveness of various intervention strategies, including: (a) using heat exchangers to recover some of the heat from the waste water, (b) using local ground water in a closed loop to heat the river, (c) pumping treated water from its downstream location back upstream of the dam, (d) installing traditional ice booms and installing tension ice booms (that have a net floating on the river surface on the downstream side).
Year: 2002