Liquid purification or separation – With heater or heat exchanger – With treating fluid addition
Patent
1983-07-25
1985-01-01
Therkorn, Ernest G.
Liquid purification or separation
With heater or heat exchanger
With treating fluid addition
210220, 2102422, 2102423, 2105121, 210923, E02B 1504
Patent
active
044915187
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to a device or craft for selectively picking up a layer of light liquid, such as hydrocarbon, floating on the surface of a sheet of water likely to be subjected to a swell, usable more especially for cleansing zones covered with a layer of hydrocarbon following accidental discharges.
It should first of all be recalled what the problems are which are met with in the construction of a cleansing or depolluting device for use at sea.
Polluting hydrocarbon is in the form of a thin layer (of the order of a millimeter) formed by a hydrocarbon phase which may be very viscous due to evaporation of the light components or by a polyphase emulsion of hydrocarbon with sea water and/or air, following the stirring caused by the waves.
The device must be designed for cleansing as large a width as possible at each passage. The water inevitably picked up at the same time as the pollutant must represent as small a fraction as possible of the part extracted and stored. To obtain this latter result is thwarted by the very small ratio between the thickness of the pollutant layer and that of the water layer which must necessarily be picked up because of the variations in level due in particular to the swell.
Patent publication No. FR-A-2 467 769 describes a device of a type which comprises a hull provided with propulsion means for running before the sea, the hull having a central part projecting forwardly with respect to the two lateral parts which define with the central part ducts leading to separators and the central part having deflector means such as fins for creating swirls whose orientation tends to reduce the divergence of the surface flow about the hull.
The deflector means allow a double result to be reached. On the one hand, the device thus sweeps the sea between two current lines which, upstream, have a much greater separation than they would have had in the absence of these means; correspondingly, there is a thickening of the light liquid layer at the intake of the delivery ducts. Because the pick-up operation takes place running before the sea, the wake of the ship causes damping of the swell.
Thus, thicknening by a factor of the order of 2.5 may be achieved between the open sea upstream of the device and the water intakes of ducts 16. In practice, because of the convergence of the current lines, a thickening rate of the hydrocarbon layer of the order of 2.5 may be achieved.
Such thickening remains however very insufficient for feeding a separator, more especially of the centrifugal type, under conditions such that the ratio between pollutant and water in the flow picked up is acceptable.
The invention aims more particularly at providing a pick-up device in which progressive thickening of the light liquid layer is achieved along an open stream flow until separation by a free surface swirling procedure, with vertical axis and central pick-up.
This thickening must be carried out very progressively from the stem of the central part as far as the pick-up by an axial plunger tube. In fact, the equilibrium of a light liquid layer of variable thickness causes this liquid to be carried along by the water resulting from a speed discontinuity at the interface with a tangential constraint proportional to the gradient of the square of the thickness; this equilibrium becomes unstable beyond a limit value of this constraint, so also of this gradient or of the speed discontinuity.
To this end, the invention proposes a device of the above-defined type, characterized in that each duct or passage comprises a floor with deviating profile whose leading edge projects forwardly of the ducts, for slowing down the flow upstream of the leading edge and causing progressive thickening of the layer, and in that it is separated by an approximately vertical dividing wall over a part of its height extending at a distance from a horizontal limit of the water layer in two sub-channels one of which communicates upstream with the inlet of the duct and, downstream, with the separa
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patent: 3744254 (1973-07-01), Fennelly
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Benaroya Henry
Cadoux Jean-Elie
LeFoll Jean
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