Author(s): F. Al-Hulail; S. Neelamani
Linked Author(s): Neelamani Subramani
Keywords: Tide induced current; Silt and clay; Submarine pipeline; Seawater intake; Maintenance dredging; Power plant cooling system
Abstract: For more than two decades, an intake channel supplying seawater for a power plant in Kuwait is suffering with significant trapping of Total Suspended Solids (TSS). Maintenance dredging of about 400,000 m 3 /year is carried out with a total annual maintenance cost of about 20 to 25 million US$. There is a proposal to increase the capacity of seawater intake for a proposed 2050 MW additional power plant and hence further increase in the TSS settlement is anticipated, if the present sea water intake system is used. Alternative type of seawater intake system, which can reduce the entry of total suspended sediments, is explored. Before fixing another alternative seawater intake system, it is necessary to assess the TSS level in the seawater at different water depths, at different tidal phases and at different elevations. Seawater samples at two different locations (one in a shallow water of 1.37 m and another in a deep water with water depth of 5.67 m with respect to Kuwait Land Chart Datum (KLCD) is selected. At each locations, 24 water samples were collected, at three different elevations (one at the surface, one at mid-depth and one closer to the sea bed) and for 8 different tidal phases, covering the low tide and high tide. The TSS is expected to vary when the tide is varying due to the change in flow velocity of sea water, which results in different sediment carrying capacity of the flowing water. The average TSS value at seabed, mid-depth and at the surface in shallow water is obtained as 289.75 mg/l, 278.63 mg/l and 258.38 mg/l respectively. The average TSS value at seab ed, middepth and at the surface in deeper water is obtained as 431.88 mg/l, 355.63 mg/l and 248.13 mg/l respectively. It is hence advisable to draw water closer to the free surface in order to reduce the TSS load entering into the power plant system. It is also found that the TSS level reduces significantly (40% to 60%) when the flow velocity of sea water is minimum. Hence it is better to avoid taking in the seawater when the sediment carrying capacity of the seawater is high during high currents. This paper provides the details of variation of TSS with tide level variation at two locations and at three different elevations in Khor-Sabiya, Kuwait. This study will be useful for similar locations around the world for selecting a suitable seawater intake system which will help in the reduction of sediment load entering into the power plant.
Year: 2010