The Offshore System & the InvisiHead
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Elmosa
Canada
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Seawater intake system of Elmosa offshore type is made up of the InvisiHeadpatented -the backbone of the system, the Pipeline whether its steel, steel lined with polyethylene, GRP, concrete, or high density polyethylene (HDPE) pipe, and the NatSeppatented. The omni directional InvisiHead intake head system adds to the performance of the offshore system. It is fitted to the upstream end of the intake system pipeline located some distance into the sea from the shoreline. Entrance velocity is lower than 0.091 m/s (0.3 fps). The approach velocity is extremely slow - <0.0027 m/s (0.009 fps) - the InvisiHead intake head becomes hydraulically invisible to marine life and debris. In other words, the intake head does not act as a sink point and therefore does not suck in sediments, marine life, or debris. No impingement or ingress of fish.
The InvisiHead
Super slow entrance velocities also lead to lower head losses and lower level draw downs at the pump intake basin. The InvisiHead entrance section is hydraulically fine tuned in lab tests. The entrance dimensions are not arbitrarily selected but hydraulically calculated in multi dimensional approach and through model setup and testing. Each dimension is a function of the steady flow velocity. Eddies through this approach are totally eliminated thus head loss at the InvisiHead is reduced to a negligible level - < 0.2 millimeters.
Should the dimensions become out of phase as the case in standard intake head inlets and with the streamlines leaving the approach stage and reaching the entrance (which is usually the case when one of the dimensions like the height or the width is arbitrarily chosen and the other is calculated by dividing the area by the chosen dimension), eddies will form and multiply causing turbulence and flow disturbance at the head entrance. This causes a higher pressure drop that will result in higher suction and thus higher head loss and level reduction at the intake basin, and higher pumping energy. That is why we tune the flow with the height and the circumference of the InvisiHead. Once the three are in phase, the InvisiHead is kept to minimum in size, the head loss is kept to minimum and the level drop of water is kept to the absolute minimum at the NatSep intake basin. When that is done, less sediment and debris flows through, smaller pipelines will satisfy the flow capacity required, smaller and shallower NatSep basins will be needed. All these optimization factors translate into lower initial investment and lower operation and maintenance costs for the intake system and for the overall plant costs.
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