A physical model, built at an undistorted scale of 1:15 tested the original design of the six drum screen and nineteen cooling water pump intake connected to header bay. The capacity of origin water intake including huge pump station and drum screen is 400,000 m3/hr. The study objectives were to evaluate as-designed screen bay and pump bay performance and to propose design modifications to optimize intake flow conditions with respect to head-losses, uniformity of the approach flow, evenness of pump throat velocity distribution, and free and subsurface vortex formation. The model was built and operated in accordance with froude-number similitude. It allowed accurate representation of complex flow patterns caused by the physical geometry of the approach bay and pump bays. The major factors that can affect the selection of a concept and design development for a water intake are: a) The occurrence of dead water zones, flow separation or reverse flow b) Vortex building and air entrainment in the pump compartments c) Submerged vortices building in the pump compartments d) Low velocity area e) Strong rotational flow f) Strong cross flow appear in front of pump units g) Pre rotation in the pump suction lines. Dye injection was used to examine the stratified flow behavior along water. The existing design of the pump bays was found to produce a uniform, symmetrical flow distribution in the approach flow, weak but persistent floor and side-wall-attached submerged vortices, avoiding cross flow and reverse flow in front of the pumps and negligible swirling motion in the pump suction. Modified design includes (i) profiling low velocity area (ii) adding flow deflectors along inner walls (iii) infill area of low velocity (iv) adding suspended baffle in front of drum screens (v) adding diffuser block in front of pumps (vi) provision of floating booms in front of pumps.

Background and aim: A sea water intake, with original design of the six drum screen and twenty sea water pump intake with very different flow rate connected to header bay. The capacity of Origin Sea water intake including huge pump station and drum screen is 200,000 m3/hr. The purpose of the mathematical hydraulic model test of the sea water pumping station is to verify that the basin allows a good operating condition for each pump. To ensure a good operating condition for each pump, the design of the seawater basin has to insure: • A correct filter working; • Low transversal velocities; • A flow without vortex. Method and material: The mathematical model of the basin allows to know the flow and to verify: • The main dimensions of the pumping station; • The distance between the inlet ducts and the filters; • The distance between the filters and pump chambers. Result: in the first basin, the flow patterns no problems. Only swirl at the exit of culverts and near the free surface, and two areas where the flow has no velocity were observed. In the downstream other filters, we observe also a circulation that generates a tangential velocity. Conclusion: The mathematical model of the sea water pumping station has allowed calculating three cases (without and with filter stopped) for the low water level and nominal flow rate. In most difficult case, we observe some recirculation, mainly near the free surface, without more influence on principal flow. In the three cases, the distribution of the flow rate between the drum screens is uniform; the gap is inferior to 2%. At the entry of the pump chambers, the velocity fluctuations and the angle are low. Consequently, the secondary flows in pump chambers will be limited.

No abstract