GB2354462A

GB2354462A - Vortex device for separating oil or floating algae from water; combinations of separators

Info

Publication number: GB2354462A
Application number: GB9925767A
Authority: GB
Inventors: Thomas Merlin Maddock; Alun K Lewis
Original assignee: MANTIS OIL SEPARATION Ltd
Current assignee: MANTIS OIL SEPARATION Ltd
Priority date: 1999-09-22
Filing date: 1999-11-01
Publication date: 2001-03-28
Also published as: GB9925767D0

Abstract

A vortex device for separating oil (or floating algae) from water comprises a chamber 1a, 73a, means to impart a rotational movement to the oil and water so that a non-turbulent vortex of oil floats on the water, means for removal of oil from the vortex, an outlet 41 for the escape of water from the chamber, and variable flow regulating means 8a,80a regulating the flow of water through the chamber. There may also be a similar means 85a regulating flow of oil from the chamber, and the inlet flow may be controlled by a hinged gate. The means imparting rotational movement may be a tangential entry port, a stirrer, electromagnetic fleas, or as shown a spiral track. In Fig 4, the vortex device is used in conjunction with a tilted plate separator 40 and filter elements 65 which remove residual traces of oil. In Fig 8, water upstream of the vortex chamber may bypass it along pipe 100, this flow being controlled by a further regulating means 101. In Figs 9 and 10 (not shown), the device is buoyantly supported in a body of water and propelled by a marine outboard engine.

Description

2354462

VORTEX OIL SEPARATION SYSTEM Technical Field

It is known to separate oil from water by methods which include the formation of a rotating fluid mass in which separation occurs under the influence of centrifugal forces. Where the oil and water to be separated are present in a naturally occurring or artificially generated moving stream, it is well known to generate the rotational movement by causing tangential entry of the flow into a suitably shaped chamber or enclosure whose walls direct the flow into a rotational path.

In the VORTOIL (T.M.) System, oil contattriated water passes under pressure through a tangential inlet at high speed into an hydro cyclone chamber to create a swirling vortex in which the fluid swirls at rates of up to 30,000 rpm. Very high centrifugal forces are generated and the oil n-igrates almost instantly to the core of the vortex from which it is withdrawn through an outlet located near the inlet. The de-contaminated water is discharged from the other end of the hydro cyclone chamber.

In the CYCLONET (T.M.) System, an unit which comprises an hydrocyclone chamber and a forwardly directed scoop is attached to a boat. When the boat is driven forward, the scoop skims floating oil and a moderate amount of surface water. The fluids are driven through a tangential inlet slot leading into the hydrocyclone chamber which is tapered towards its base. A tangential outlet slot is located adjacent to the base. By reason of the forward speed of the boat and the tangential entry and outlet slots, the fluids form a rotating mass in which oil separates from the water by centrifugal force and gravity and rises to the top whence it is pumped out to storage. Oil decontaminated water flows out through the tangential outlet slot. During operation, the CYCLONET units may be mounted on either side of the hulls of trawlers, supply vessels, barges, and sea-going tugs. The operating speed is in the region of 3.10 knots. The rate of flow of water through the CYCLONET hydrocyclone chamber and the fluid surface level within the chamber will be governed by the dimensions of the slots, the forward speed through the water of the boat to which the unit is attached and/or the depth at which the scoop is set. The decontan-iinated water flows freely out of the chamber through the tangential outlet slot and away into the surrounding body of water.

In another system referred to by its promoters as "Captain Blomberg's Hydrodynamic Circ&', boom means are used to direct floating oil carried by a river or tidal flow into the side inlet of an hexagonal enclosure defined by its side walls and open above and below. The enclosure is mounted on a small boat provided with a pushing rudder on the opposite side of the enclosure. The side inlet with its boom means are disposed to face upstream. The side inlet provides what may loosely be called a tangential entry into the enclosure. Within the enclosure, floating oil and a layer of water on which it floats are diverted by the side walls so as to form an eddy within which the oil accumulates at its centre. The oil is sucked out of the centre of the eddy and is passed to a floating storage bag. The water flows out through the open base area of the enclosure to re-join the river or tidal flow below.

Disclosure of the Invention

In general, the present invention relates to apparatus and a method for separating oil from water in which rotational movement is imparted to a flow of oil and water admitted into a vortex chamber so as to form a rotating fluid mass within which a non-turbulent vortex of oil floats on a swirling stream of water that passes through the chamber. The water escapes from the vortex chamber through outlet means located below the level of the floating oil. The present invention in its several aspects brings in the regulation of the associated features of (a) The rates of fluid flows through the vortex chamber, and (b) Fluid surface levels within the vortex chamber and externally at the inlet. In each case, the level will depend upon the downstream fluid flow associated with it.

The expression "fluid surface level" as used in this specification shall mean the uppermost liquid surface level at any point. Thus, where water alone is present, the fluid surface level will be the level of the surface of the water. But where oil floats on the surface of the water, the fluid surface level will be the level of the surface of the oil. In the working of the several aspects of this invention, the fluid flows and surface levels of both water and oil and their mutual interaction fall to be considered. Regulation of any one or more of the fluid flows can influence the operation other fluid flows and hence the fluid surface levels with which the others are associated in a complex hydrodynamic system..

Direct regulation of water flow: "Means X'.

According to the First Aspect of the present invention, there is provided apparatus for separating oil from water which comprises:

(i) A vortex chamber adapted to admit through an inlet a flow of oil and water; (ii.) Means adapted to impart a rotational movement to the admitted oil and water so as to form within the chamber a rotating fluid mass within which a non-turbulent vortex of oil floats on the water; (iii.) Means for the removal of oil from the oil vortex-, (iv.) Outlet means adapted to be located below the level of the floating oil for the escape of water from the vortex chamber, and (v.) Variable flow regulating means located at or downstream of the outlet means and adapted to regulate the rate of flow of water through the chamber.

In an important to appreciate for a full understanding of the present invention that the variable flow regulating means as mentioned under (v.) above will also serve to regulate the fluid surface level within the vortex chamber. In general, in the context of the present invention and in the absence of other factors, regulation of a liquid flow will inevitably result in the regulation of the fluid surface level of the liquid upstream, and vice versa. Separation of floating oil.

There are circumstances where the oil to be separated from water floats as a discrete layer on the water surface. In such a case, the rate of flow of water through the vortex chamber may be regulated indirectly. Such indirect regulation may be additional to or in substitution for the direct regulation of the flow as mentioned above in relation to the First Aspect of the present invention.

Indirect regulation of water flow: "Means B".

According to the Second Aspect of the present invention, there is provided apparatus for separating floating oil from water which comprises:

1.) A forward part adapted to receive a flow of water that bears a floating layer of oil; 2.) A vortex chamber located downstream of the forward part adapted to admit through an inlet an upper layer of the flow of water together with the layer of oil that floats on such upper layer; 3.) Means adapted to impart a rotational movement to the admitted oil and water so as to form within the chamber a rotating fluid mass within which a nonturbulent vortex of oil floats on the water; 4.) Means for the removal of oil from the oil vortex; 5.) Outlet means adapted to be located below the level of the floating oil for the escape of water from the vortex chamber; 6.) By pass means having inlet means in the said forward part adapted to admit water from below the oil/water interface upstream of the vortex chamber inlet and to divert the admitted water past the vortex chamber, and 7.) Variable flow regulating means adapted to regulate the rate of flow of water through the by pass means.

Variable flow regulating "Means A to D." Means A.

The expression "Means A" is used herein to refer to the direct variable flow regulating means mentioned under (v.) above in relation to the First Aspect of the invention. Means A may act alone according to the present invention to regulate the flow of water through the vortex chamber, uninfluenced by any other variable flow regulating means. Use of Means A alone represents the simplest aspect of the working of the present invention.

The present invention when broadly defined covers the cases where one or a plurality of other variable flow regulating means is or are put to use either in conjunction with Means A or otherwise. Each such means will also regulate as a matter of course the particular upstream fluid surface level related to the flow that it regulates. When simultaneous use is made of two or more such means, there is set up a complex hydrodynamic system. The other means are:

Means B: Means mentioned under 7.) above in relation to the Second Aspect of the invention and applicable only where floatirig oil is to be separated from water, Means C: Means adapted to regulate the rate of flow of oil during its removal from the floating oil vortex, and Means D: Means adapted to regulate the rate of flow of floating oil into the vortex chamber through the vortex chamber inlet, and applicable as for Means B. By regulating the rate of flow of water through the by-pass means, Means B is also adapted to regulate the outer fluid surface level upstream of the vortex chamber at its inlet. Given for the time being i. free entry of the flow of water and floating oil into the vortex chamber, ii. constant conditions for the escape of water from the vortex chamber and iii. the absence of simultaneous variati6n of any of the other said flow regulating Means, a change in the outer fluid surface level at the vortex chamber inlet results in a corresponding change in the fluid surface level within the chamber. The rate at which water escapes from the vortex chamber is influenced by the hydrodynamic pressure at the water outlet which in turn depends upon the fluid surface level within the chamber. Hence, where applicable, Means B constitutes a variable flow regulating means which, because of its effect upstream of the vortex chamber inlet is adapted to regulate the rate of flow of water through the chamber.

Regulation of the rate of removal of oil: "Means C".

According to the Third Aspect of the present invention, there is provided apparatus for separating oil from water which comprises each of the features (i) to (iv) mentioned above in relation to the First Aspect of the present invention together with variable flow regulating means adapted to regulate the flow of oil from the oil vortex and out of the vortex chamber.

Regulation according to Means C will result in the varying of the amount of oil in the oil vortex, and hence its size. This will affect the fluid surface level within the vortex chamber and, as a result, the hydrodynamic pressure at the water outlet.

Regulation of the rate of inflow of floating oil: "Means D".

According to the Fourth Aspect of the present invention, there is provided apparatus for separating floating oil from water which comprises:

(L) A vortex chamber adapted to admit through an inlet a flow of water together with a layer of oil that floats on the water-, 2.) Means adapted to impart a rotational movement to the admitted oil and water so as to form within the chamber a rotating fluid mass within which a nonturbulent vortex of oil floats on the water (3) Means for the removal of oil from the oil vortex- (4.) Outlet means adapted to be located below the level of the floating oil for the escape of water from the vortex chamber, and (5.) Variable flow regulating means controlling the upper part of the inlet and adapted to regulate the flow of floating oil into the vortex chamber.

Where the flow of oil into the vortex chamber is restricted, an ever thickening layer of floating oil will build up at the inlet and the thickness of the floating oil vortex inside the vortex chamber will decrease, and vice versa. Water continues its flow below the oil layer into the vortex chamber. The factors determining the rate of flow of water through the vortex chamber will include the thickness of the said outer layer of oil and of the inner floating oil vortex, each of which will have a bearing on the hydrodynamic pressure at the water outlet. As the rate of inflow of the floating oil is varied, the rate of flow of water through the outlet will respond pending restoration of a steady inflow of the oil.

Any of the variable flow regulating Means A to D mentioned above may be constituted by fluid valves or gates of the known kind that control the passage of a fluid through a pipe or aperture. Such valves or gates may be operated manually or else automatically in response to signals from sensors located, as may be appropriate, either within the vortex chamber or in the forward part of the apparatus which indicate the surface fluid levels and/or the oil/water interface levels at their several respective locations.

Where the apparatus of the invention is located on a stable support or on a support that is not subject to disruptive periodic or random physical movement, each or any of Means A to D may be operated by reference to the control of fluid flow over a weir rim. The weir rim may be provided by:

(a) A sluice gate arrangement of the known kind, or (b) Save in the case of Means D, a downstream weir valve arrangement as described in the Specification of our co-pending United Kingdom Patent Application No. BP 9922369.5 (believed by the present applicants to be novel.) For the purposes of this specification, such an arrangement will be referred to below as a "Tulip Valve"; and it is described below.

The Tulip Valve is not appropriate for use as Means D. However, Means D may advantageously be operated using an hinged gate extending across the upper part of the vortex chamber inlet and opening to admit fluid flow into the chamber. Preferably, such admission is effected in the same direction as the rotational flow within the chamber at the location of the inlet.

Weir acting sluice gates constitute the preferred form of the regulating Means A and, where called for, Means B and/or Means C. Amongst such gates, Tulip Valves are particularly preferred because of their precision, reliability and ease of handling.

Marine Application.

The apparatus according to the present invention may be mounted on to a boat or else provided with buoyancy means in order to remove floating oil from the surface of a body of water, e.g. out at sea or on a lake, harbour, river or other water surface. For the purposes of this specification, such user of the apparatus will be referred to below as "Marine Application".

The operation may from time to time be affected by wave motion or unpredictable current flows. In Marine Applications of the invention such as the removal of an oil slick at sea, the prime object is frequently the physical removal of as much of the floating oil contaminant as possible. The purity of the water that has passed through the apparatus may well be a secondary consideration. Likewise in an industrial context where the water from which oil has been separated is to be recycled. In such circumstances, submerged sluice gate valves other than those acting by reference to the height of a weir rim, (i.e., other than "weir acting sluice gates") may be found to perform adequately as the variable flow regulating Means A, B and/or C.

On the other hand, when operating on inland waters, the purity of the water discharged from the apparatus of the invention could be a matter of prime importance calling for the precision and reliability provided by the Tulip Valve as the Means A. Under calm conditions, the same Tulip Valve may also be employed in the method described below for the removal of residual oil that has survived passage through the vortex chamber.

Rotation of the fluid mass within the vortex chamber. When a layer of oil floats on a water vortex, the combination of the resulting drag effect of the water and of centrifugal/centripetal forces transforms the layer into a discrete oil vortex having the shape of an inverted bell-curve that spins around its axis. The height or depth of the curve at its centre will vary, inter alia, with the speed of rotation of the oil up to the point where the speed becomes excessive and oil breaks off the bottom of the vortex.

The rotation of the fluid mass within the vortex chamber may be brought about by tangential entry of a fluid flow into a chamber having an appropriate inner cross-sectional configuration, in particular, a circular inner configuration. Rotational movement of the fluid may also be caused or enhanced by known means, e.g. by use of stirrers and/or electro-magnetically driven "fleas". In the preferred embodiments of the present invention, rotational movement is brought about at least in part using suitably disposed guide means adapted to direct the lower level of an incoming flow of oil and water into a rotational path so as to impart a rotational movement to the remainder of the flow by a drag effect. Such means may function either with or without the assistance provided by tangential entry of the fluid flow.

Oil and water that is fed to a vortex chamber by the use of a conventional pump will, in the ordinary course of events flow through the vortex chamber inlet as a random mixture. On the other hand, the vortex chamber may receive a two layer liquid flow through the inlet, being a discrete floating layer of oil supported by a layer of water.

This will be the case:

i. Following upstream stabilisation during which the oil and water is allowed to flow gently along extended channels or conduits so as to allow oil time to separate out as buoyant droplets which rise to the surface of the water. Submerged corrugated separator plates, and, in particular, submerged "Lerner Plates" as defined below with their groove depths increasing along the longitudinal direction of flow may be disposed within the channels or conduits to promote the separation of the oil.

ii. During Marine Applications of the invention.

When using means other than tangential entry to generate or enhance rotation of the fluid mass within the vortex chamber, it is preferred that such means operate (a.) below the level of the interface between the incon-dng oil and water layers in cases coining under i. or ii. above, and (b.) in other cases, below the level of the oil/water interface after a floating layer of accumulated oil has been formed following upward migration of dispersed oil, as the case may be, and C. in every case, below the level of the oil vortex when and after it is formed. "Clock Spring Guide" The expression "Clock Spring Guide" is used herein to refer to a particularly effective guide means for effecting or enhancing fluid rotation within the vortex chamber. Reference is made to the description of the device and of its applications set out in the specification of our co-pending United Kingdom Patent Application No. GB 9922368.7. The Clock Spring Guide may be used in conjunction with other rotation inducing means, e.g. tangential entry. Alternatively, it may be used as the sole rotation inducing means, as in the case of a "frontal" non tangential entry of the oil and water.

Definition. The Clock Spring Guide is defined for the purposes of this specification as a device for converting a flow of liquid into a vortex in which a wall member in the form of an helix when seen in plan view stands on a base member so as to provide an helical path of progressively diminishing radius adapted to receive the flow or a selected layer of the flow and guide the same along the said path to the zone around the centre of the helix, such zone comprising liquid outlet means passing through the base member. Where the Clock Spring Guide is located within or constitutes part of a vortex chamber provided with tangential entry means disposed in the same direction as the helical path towards the centre of the helix, the first circuit of the helical path will in practice fie between the inner wall of the chamber and the outer whorl or coil of the helical wall member of the Clock Spring Guide.

Seen from above, the helical wall member resembles an unwound spiral clock spring the inner end of which stops short of the geometrical centre of the helix and preferably stops at or short of the outlet means. Hence the designation "Clock Spring Guide". A Clock Spring Guide provides very effective, smooth acting means for converting a liquid flow into a vortex. It may be present within a vortex chamber acting in conjunction with tangential entry means. In such a case, it provides additional rotational impetus to the liquid or to a layer of the liquid which enters the helical path over and above tangential entry alone. Alternatively, the Clock Spring Guide may be disposed within a vortex chamber to receive all or part of the liquid flow as it enters so that the same does not impinge against the chamber wall.

In operation, the whole or part of a liquid flow is guided along an helical path of diminishing radius to the zone around the centre of the helix. Where part only is thus guided, in practice, it constitutes the lower layer of the flow. As it passes along the helical path, such lower layer exerts a drag effect upon the remainder of the flow so that all the flow is transformed into a vortex.

When a Clock Spring Guide is used to generate an oil vortex in the separation of oil from water, it is preferred that the level of the upper rim of the helical wall guide be progressively lowered in the direction of the centre of the helix. This is done in order to accommodate the pendulous submerged portion of the oil vortex after it has been formed. Ideally, the path traced by such upper rim will be located away from the interface between the oil vortex and the supporting water, but will follow the contour of the nearest point on the interface. The best results are obtained where the oil vortex does not extend downwardly as far as the upper rim of the helical wall member at any point. The Clock Spring Guide may also be put to use independently so as to act as a vortex chamber in the manner described under the heading "Independent Clock Spring Guide" in the aforesaid specification of our co-pending United Kingdom Patent Application No. GB 9922368.7. In such a case, an inlet is provided at or near the mouth of the helix between the upper part of the helical waH member that constitutes the outer circumferential coil or whorl and the upper part of the first inner wall member coil or whorl. The inlet fies above a barrier plate that spans the the gap between the outer and first inner wall member coils or whorls at or near to the mouth of the helix and extends downwardly to the base member. The height of the barrier plate determines the height of the inlet above the base. Oil and water may be fed into the device through the inlet. The device may also be used to separate floating oil. To this end, it is immersed in a surface oil contaminated body of water to a depth that permits the admission of a flow of oil and -Il- a supporting layer of surface water through the inlet. Downstream of the inlet, an underlying layer of the water enters the helical path defined by the wall member, and a primary vortex is formed leading to the formation of the floating oil vortex as more oil/water feed mixture flows in. Care should be taken to ensure that the height of the helical wall member untially decreases along the direction towards the centre at a rate that will ensure minimal disruption at the oil/water interface when the oil vortex is formed. The Clock Spring Guide provides the following practical advantages: (a) It can be adapted to act selectively at any level of a liquid flow. In practice, and when used in an oil separation process, the best results are secured where the helical wall is adapted to act on the underlying layer of water. The primary vortex thus generated exerts a drag effect upon the overlying water so that it becomes the upper part of the water vortex. This in turn exerts a smooth drag effect upon the floating oil over the whole area of the oil/water interface to give a stable, non turbulent oil vortex. (b) It provides an effective means for generating a vortex in circumstances where it may be difficult, expensive or impractical to provide a tangential entry into a vortex chamber. It can be used in conjunction with a direct entry port. A direct entry port is, in general, easier to make and seal than a tangential entry port. (c) It acts to dampen down turbulence, pulsations, vibrations and other disruptive elements that may accompany the liquid flow at the inlet. As a result, it provides a smoother and more regular rotating fluid mass than that provided by tangential entry alone or by mechanical stirring. This property is put to good effect in the separate use of a Clock Spring Guide as the principal operative element in a method for stabilising a liquid flow by the dampening down and/or elimination of turbulence, pulsations and/or vibrations transmitted or carried by the flow. (d) It provides a very effective method of converting a fluid flow into a rotating fluid mass of relatively high angular velocity, giving a substantially higher "conversion ratio" of angular velocity of the mass to inlet flow speed than tangential entry alone. (e) It provides an effective alternative to tangential entry where difficulties of cost or design associated with the provision of tangential entty are to be avoided.

(f) By varying the characteristics of the helical wall member, including its height, the contour of its upper rim and the tightness of the coils of the helix, the characteristics (including speed of rotation) of the vortex or of different parts of the vortex that is generated may be varied.

Removal of oil from the oil vortex.

As the oil/water feed continues to enter the vortex chamber, additional oil accrues to the floating oil vortex which remains in the chamber. The oil vortex is supported by the continuous stream of water that flows between the inlet and the vortex chamber water outlet. Where use is made of the Clock Spring Guide as the vortex begetter, the outlet means passing through its base member will constitute the vortex chamber water outlet. When the oil vortex, however begotten, has attained its desired size, oil is withdrawn aL' a rate that is dependent upon the rate of accretion of additional oil from the oil/water feed flow. The thickness or depth of the oil vortex will increase with an increase in its speed of rotation up to a critical speed of rotation beyond which its inverted bell-curve configuration is impaired or lost as oil breaks off the lower part of the vortex. It is therefore important to limit the speed of rotation so as not to arrive at such a critical speed. In the context of the present invention, this is done by limiting the rate of flow of water through the vortex chamber. The speed of rotation of the oil vortex and that of the surrounding swiding water is dependent upon such rate of flow. Means A as defined above will regulate the rate of flow, either acting alone or as influenced where relevant by Means B and/or, to a limited extent, Means C and/or Means D.

A centrally disposed horizontal baffle plate located below the oil/water interface will serve to counter the tendency of the oil to break away from the bottom of the oil vortex and promote the oil vortex's integrity. Also as a precautionary measure, there may be provided, in addition, small supplementary and preferably symmetricaUy disposed outlet apertures at or near the periphery of the base member of the vortex chamber to take away some of the peripheral swirling water that tends to encourage oil to break away ftom the oil/water interface around the lower parts of the oil vortex.

The oil may be removed from the oil vortex through an oil removal pipe having its inlet immersed within or at the surface (see below) of the oil vortex. Removal may be upwardly by way of suction or downwardly by way of gravity. For upward removal, the inlet of the oil removal pipe may be dipped into a cup shaped sump immersed within the oil vortex. In general, however, removal is preferably effected downwardly by way of a centrally disposed oil removal pipe that extends downwardly from the inlet and which may usefully support the centrally disposed horizontal baffle plate. Under stable conditions, the shape of the oil vortex ensures a reliable

supply of oil from a deep and turbulence free reservoir of oil that surrounds the oil removal pipe inlet.

The shape assumed by the oil vortex also provides an advantage when operating under unquiet conditions, e.g., where outside wave motion results in uncontrolled movement of the support or mounting of the apparatus and in fluctuations in the fluid surface level within the vortex chamber. To the extent of the depth of the vortex in any particular case, protection is afforded against fluctuations that would result in the entry of water.

Removal of oil by application of the "Density Differential" principle.

When a layer of oil floats on water, the fluid surface level is elevated. This phenomenon is a necessary consequence of the difference in the density as between oil and water. Since the density of floating oil is less than that of water, it follows that the volume of floating oil required to displace a given volume of water will be greater than the volume of water displaced. The thicker the layer of the floating oil, the more will its surface be elevated. Advantage is taken of this phenomenon, (referred to herein as the "Density Differential" principle,) by setting the fluid surface level within the vortex chamber when water alone flows through the chamber at an appropriate level below the inlet rim of a centrally disposed and downwardly extending oil removal pipe. When an oil/water feed flow enters the chamber, a floating oil vortex is formed around the inlet. As more oil/water feed enters, more oil accumulates within the oil vortex. Its thickness increases. The fluid surface level of the oil rises. Where the original water surface level has been appropriately set, the surface level of the oil will rise above the level of the rim. Oil will flow into the inlet and out through the oil removal pipe for collection and storage.

Removal in practice. When using a downstream weir acting valve as the downstream Means A to regulate the fluid surface level within the vortex chamber, the "Density Differential" principle for the removal of oil is applied by establishing the appropriate difference in level between the oil removal inlet rim within the chamber and the level of the weir rim of the downstream valve. The inlet means themselves may conveniently be constituted by one or more lateral slots in an upwardly disposed pipe. It may be convenient to make the level of the inlet rim adjustable, e.g. by telescopic mounting of the inlet or its support on to the oil removal pipe. The fluid surface level in the vortex chamber is regulated by the weir rim level of the downstream valve. In practice, to establish the correct final settings for oil removal, the downstream weir rim is initially set to provide a relatively low fluid surface level within the vortex chamber with water alone flowing through it. Such surface level will be below the anticipated eventual working level of the water surface. A stream of oil/water feed is then fed into the vortex chamber. An oil vortex is formed. It is allowed to accumulate oil and grow to the desired size. At this stage, its surface will lie below the oil removal inlet rim. The downstream weir rim level is adjusted so as to raise the fluid surface level within the vortex chamber to the point where the oil vortex surface level arrives at the level of the oil removal inlet rim. That provides the permanent setting for the downstream valve. As more oil from the oil/water feed accrues to the oil vortex from the incoming oil/water feed stream, oil simultaneously flows over the oil removal inlet rim and out of the chamber of its own accord for collection and storage.

The preferred downstream weir acting valve means for putting the "Density Differential" principle into effect is a Tulip Valve.

Means A provides direct regulation of the appropriate surface fluid level within the vortex chamber for the application of the "Density Differential" method of the removal of oil from the chamber according to the present invention. Means B provides indirect regulation and can operate independently of Means A. Means C and Means D, by regulating the outflow and inflow respectively of the oil will influence the amount of oil in the oil vortex and hence its fluid surface level. within the vortex chamber. The operation of each of the Means can have a bearing upon the operation of the others. For example, if Means B were used to contribute to the regulation by Means A of the flow of water through the vortex chamber, the relevant weir valve rim settings to be adjusted as against the setting of the oil removal inlet rim would include the setting of the valve means arranged to regulate the flow of water through the by-pass means. As a general rule, when the broad scope of the application of the "Density Differential" principle falls to be considered, account will have to be taken of each of Means A to D when and insofar as they are put to use..

Tulip Valves.

A Tulip Valve as referred to herein is a weir valve arrangement as described in the Specification of our aforesaid co-pending United Kingdom Patent Application No. GB 9922369.5.

Definition. A Tulip Valve is defined for the purposes of this specification as a weir valve which comprises a pipe member having an expanded upper end bounded at least in part by a rim, the length of the rim or of its horizontal projection being significantly greater than the inner circumference of the pipe member, together with means whereby the vertical disposition of the rim may be regulated so that it acts as the rim of a weir of variable height that governs i. the rate of flow of liquid out of, or alternatively into the pipe member and/or ii. respectively the surface level of a body of liquid which for the time being is: a. connected to liquid within the pipe member, or b. connected to liquid outside the pipe member.

The ratio of the length of the weir rim or of its horizontal projection as the case may be of a Tulip Valve to the inner circumference of the pipe member referred to is, for practical purposes, at least between one and one third and one and one and a half to one, preferably at least two to one, advantageously at least three to one and usefully at least four to one. The rim may be contained and maintained in an horizontally disposed plane. Other configurations of the rim are possible, Thus the rim may be provided with upwardly extending parts adapted to enable the Tulip Valve to exert variable control on fluid flow by varying the level of the rim so as to vary the areas or apertures between the upwardly extending parts through which fluid will flow. The extent and variation of such flow may be ascertained and calibrated by trial and error and/or in the case of suitably shaped areas and/or apertures, by calculation..

For the purposes of the present invention, it is preferred to use a Tulip Valve that has its rim contained and maintained in an horizontally disposed plane.

in the preferred embodiments of the present invention, the weir rim bearing pipe member of a Tulip Valve is mounted telescopically onto or within a fixed lower pipe or socket, e.g. by way of a screw threaded mounting. Precise regulation of the location and of the upward and downward movement of the rim and its associated support member may be secured by means well known per se, for example by way of screw mountings, rack and pinion means or the use of intermediate support members of adjustable length. In this way, the height and movement of the pipe member supporting the weir rim may be finely tuned so as to provide precise control and adjustment of the weir rim height. Where such precise control and adjustment are not called for, the weir rim bearing pipe may be ftiction mounted.

The description below refers to the use of Tulip Valves as performing the functions of Means A, Means B and/or Means C in the several aspects of the method of the present invention. It will be understood that, where the context so admits, such description will apply also, mutatis mutandis to the use of other valve means as already referred to above. However, such other valve means do not provide the peculiar advantages that result from the use of Tulip Valves.

The use of a Tulip Valve as a downstream Means A that regulates the rate of flow of water through the vortex chamber provides significant advantages in tenns of reliability, accuracy and ease of operation when setting and adjusting the fluid surface level within the vortex chamber. With stable mounting of the apparatus of the invention, a Tulip Valve will also provide the preferred form of each of Means B and Means C, (- i. e., regulation of by-pass flow and the flow of oil from the oil vortex respectively.) The embodiment of the present invention that makes use of the "Density Differential" principle in the removal of residual oil retained by the water flowing out of the vortex chamber using a tilted plate separation device is described below. It employs the same Means A to regulate the fluid surface levels both within the vortex chamber and the separation device. The Tulip valve is ideally suited for this purpose.

By-Pass Flow Regulation Means. Means B. In the embodiments of the present invention wherein the oil enters the vortex chamber as a discrete layer floating on a layer of water, the water and oil are arranged to flow initially through a forward part of the apparatus located upstream of the vortex chamber inlet. Such forward part comprises a base member. During operation, the fluid surface level of the incoming flow at the inlet to the vortex chamber should be maintained at a constant level so far as circumstances permit. That is, so far as possible, a constant depth of fluid above the base member of the forward part should be maintained at the inlet.

To this end, the present invention provides for by-pass means to divert water from the lower part of the water as it flows through the forward part of the apparatus. This water is diverted away from the vortex chamber. Means B regulates the flow of the diverted water through the bypass means.

The provision and regulation of by-pass flow means are of particular significance in Marine Applications of the present invention. For example, in one such Application, the apparatus of the invention may be buoyantly mounted for forward movement through an oil slick. The rate at which the oil bearing surface water enters the forward part of the apparatus will depend upon the forward speed of the apparatus. At higher speeds, oil bearing surface water will pile up in front of the vortex chamber inlet. The fluid surface level at the inlet will be elevated. The fluid surface level inside the vortex chamber will rise, resulting in what could become an excessive flow rate of water through the chamber. But at lower speeds, the fluid surface level at the inlet will be depressed. The result could be an insufficient flow of water to maintain a steady (oil vortex supporting) stream of water through the chamber between the inlet and the base outlet means.

In each case, the flow of water will be regulated by Means B. At the higher speeds, Means B will be adjusted so as to admit more water into the by pass conduit. At the lower speeds, it will be adjusted so as to admit less water into the conduit. With appropriate adjustments, there will be maintained as constant an outer fluid surface level at the vortex chamber inlet as may be reasonably possible. Hence there will also be maintained as constant a fluid surface level within the vortex chamber and, in consequence, as constant a flow through the chamber as may be reasonably possible.

During operation, a variation from one area to another in the thickness of an oil slick may call for a variation in forward speed and/or in the rate of flow through the by-pass means.. The thicker layers of oil in the slick will call for slower forward speeds and/or an enlargement of the by- pass flow, and vice versa. The setting of Means B will be varied accordingly.

in general, when separating floating oil according to the present invention, variations i. in the rate of flow of the feed stream into the apparatus of the invention and/or ii. in the relative proportions of oil and water in the feed stream may be responded to in a controlled manner by the use of Means A and/or Means B. In addition, Means C and Means D are available to deal respectively with variations in the rate of inflow of oil into the forward part of the apparatus and their consequences following either of the variations mentioned under i. and ii. above. Any one of several Means will influence the effect of any or all of the others when operated simultaneously.. The by pass means are advantageously constituted by one or more pipes or conduits. Their inlet or inlets are located in the forward part of the apparatus at the level of the lower layers of the incoming water and away from the floating oil/water interface. In Marine Applications, regulation of the rate of water flow through the by-pass means may be by the use of one or more submerged sluice gates set to operate at such inlets or at any point along the by-pass pipes or conduits. In other applications, weir acting sluice gates may be used. Particularly preferred in this context is the use of Tulip Valves.

Means for regulating the flow of oil from the floating oil vortex. Means C.

In the case of Means C, the oil removal pipe is connected to variable flow regulating means adapted to control the flow of oil from the oil vortex within the vortex chamber. In this way, Means C can be used to control the surface level of the oil. Where the apparatus is provided with a stable base or mounting, and precise control is sought, the preferred Means C is a Tulip Valve. The surface level of the oil will in practice be the fluid surface level within the vortex chamber. This will influence the hydrodynamic pressure at the water outlet. Such pressure, in turn, will influence the rate of water flow through the outlet. Thus Means C may, indirectly, exert a regulating effect upon the rate of flow of water through the chamber.

It may be borne in mind that notwithstanding the maintenance of a constant fluid surface level for the floating oil vortex within the chamber, there will still be variation in the hydrodynamic pressure at the water outlet if the thickness of the floating layer is altered. This is a necessary consequence of the difference between the respective specific gravities of oil and water. In practice, such variation will be relatively minor and may for a practical purposes be ignored.

Means for regulating the flow of oil into the vortex chamber. Means D.

Means D regulates the flow of floating oil into the vortex chamber and in practice is disposed across the upper part of the vortex chamber inlet. When all or part of the floating oil is denied entry, the underlying layers of the flowing water flow freely below the oil layer through the inlet. Means D may comprise a barrier plate the upper rim of which is arranged to span the inlet at an adjustable height so as to provide a weir rim that controls the entry of floating oil whilst its lower allows free flow of underlying water into the chamber. Alternatively, it may comprise a barrier plate adapted to be adjustably lowered into the incoming fluid stream to restrict the flow of floating oil carried by the water. During operation in this case, a relatively thick layer of oil is initially allowed to build up. The level of the lower rim of the barrier plate is then adjusted appropriately to allow entry of the oil into the vortex chamber at the desired rate The preferred form of Means D comprises a pivoted gate member adapted to open and close across the upper part of the vortex chamber inlet. The gate member is arranged to open inwardly into the vortex chamber in the same direction as the movement of the rotating fluid mass within the chamber. When the gate member opens, floating oil enters the vortex chamber together with its adjacent supporting layer of water. By closing the gate means either partially or wholly, the entry of the oil into the vortex chamber is restricted or prevented and a thickening layer of floating oil builds up against the pivoted gate member.

By regulating the rate of entry of the oil into the vortex chamber, the size and thickness of the floating oil vortex within the chamber may be regulated, subject to the imposition of a constant fluid surface level by the setting of the rim of the oil removal pipe inlet and/or the effect of Means C where the same is incorporated into the apparatus.

Where Means D comprises a pivotally mounted gate member, an horizontal baffle plate may advantageously be disposed across the inlet immediately below the gate member and adapted to extend in part into the interior of the vortex chamber with its underside at a level above the rotation imparting means. Such plate may be attached to the lower edge of the gate member. Its function is to provide an initial barrier between the oil bearing incoming flow and the rapidly rotating mass of water within the chamber and to minimise the setting up of disruptive flow patterns within the vortex chamber.

Static and dynamic Marine Application in a useful embodiment of the invention, the apparatus is buoyantly supported at a partly submerged level for static or dynamic oil separation activity.

In the case of static operation, the buoyantly supported apparatus is anchored or positioned to face upstream in a river or tidal flow and fitted with a pair of forwardly extending divergent booms to direct surface oil into the apparatus. It may also be used to separate oil that has been trapped by boom means extending across a river or tidal flow or the like and diverted to the forward part of the apparatus. In addition or as an alternative to a naturally occurring river or tidal flow, the apparatus may be adapted to supplement such a flow or to generate its own flow. To this end in each case, the apparatus is provided with rearwardly directed water propulsion means, for example a pump or an outboard motor marine screw propellor adapted to act upon the flow of decontaminated water when it emerges from the final exit pipe. The propulsion means may be located within the exit pipe, or downstream of the exit pipe outlet. Water that has flowed through the by-pass means may also be directed into the same exit pipe. The propulsion means generates or enhances a compensating flow of replacement water into the forward part of the apparatus, carrying with it a layer of floating oil. Variation in the power output of the propulsion means will result in a variation in the rate at which water flows through the vortex chamber. A conventional marine outboard motor can set up and maintain a very substantial flow of water during operation. By drawing a significant proportion of such a flow from the exit pipe, a significant throughput results, and surface contaminated water is drawn into the apparatus from a wide area.

In the case of dynamic operation, rearwardly directed water propulsion means mounted downstrewn of the decontaminated water exit pipe may be adapted to act to propel the buoyantly supported apparatus in a forward direction through a body of surface contaminated water. The propulsion means also promotes the flow of the surface contaminated water into the apparatus. Forwardly extending divergent boom arms are arranged to gather and direct the contaminated water into the forward part of the apparatus. The well known characteristics of a conventional marine outboard engine make it the preferred means both for controlled forward propulsion of the buoyant arrangement and for rearward propulsion of the decontaminated water.

Removal of Residual Oil.

In an important embodiment of the present invention, residual oil that has escaped capture within the vortex chamber is separated from the water that flows out of the vortex chamber outlet. In the working of this embodiment, simultaneous use is made of the same direct variable flow regulating means, Means A that is located downstream of the vortex chamber outlet both in relation to the initial vortex separation of the oil and water and in relation to the subsequent separation of the residual oil carried by the water following the initial separation.

Simultaneous separation of the residual oil is accomplished by the use of a Tilted Plate Separator interposed within the line of flow between the vortex chamber outlet and the Means A. The preferred form of the Means A is a Tulip valve. The following description will apply, however, to the use of other appropriate flow control valves, mutatis mutandis, and especially to the use of weir acting sluice gates.

A Tilted Plate Separator as envisaged in this specification comprises one or a plurality of submerged tilted corrugated plates located in a separation chamber through which the partly decontaminated water flows from the vortex chamber outlet. The water carries with it the residue of oil that has not been separated out during the passage of the water through the vortex chamber. On entering the separation chamber, the partly decontaminated water impinges against the lower part of the downwardly facing corrugated surface or surfaces of one or more tilted corrugated plates. The flow continues along an upwardly inclined path in contact with such corrugated surface or surfaces. The upward flow may be a "cross-flow", i.e. substantially at right angles to the direction of the corrugations as in the case of the CROSSPAK (T.M.) Tilted Plate Separators. Preferably, the flow will be a "longitudinal flow" in the direction of the corrugations. The tilted corrugated plate or plates extend upwardly from the base of the separation chamber to a level that is below the water surface level. Where oil floats on the water, the plate or plates extend upwardly to below the level of the oil/water interface.

The fluid surface level within the separation chamber is regulated by the downstream Tulip Valve. The Tulip Valve simultaneously regulates the fluid surface level within the vortex chamber upstream. Within the separation chamber, the upward flow of the oil bearing water in contact with the downward facing corrugated surface of the tilted plate or plates results in the coagulation of small particles of dispersed oil into droplets. When these attain a particular critical size, they break off at the top edge of each corrugated plate and float to the surface. Over a period of time, this leads to an accumulation of the oil droplets to form a layer of oil floating on water above the corrugated plates. The several zones wherein the oil droplets float to the surface and accumulate to form layers of floating oil are referred to herein as "surface accumulation zones".

A separation chamber may comprise (a) a single surface accumulation zone, as where a single corrugated plate or else a single "Stacked Plate" arrangement is employed to separate out the oil, or (b) a plurality of surface accumulation zones, as where a plurality of discrete single corrugated plates and/or of "Stacked Plate" arrangements are so employed, e.g. in a "Serial Plate" arrangement.

Stacked Plate arrangement and Serial Plate arrangement.

A plurality of tilted corrugated plates may be arranged respectively as:

i. A "Stacked Plate" arrangement, and ii. X'Serial Plate" arrangement which consists of a. a series of single corrugated plates acting in sequence, or b. a series of discrete units each comprising two or more such plates in a Stacked Plate arrangement acting in sequence, or C. any combination of a. and b. Stacked Plate arrangement.

In this case, two or more corrugated plates are arranged within a separation chamber in a stack of substantially parallel tilted plates. Within a stack-of plates, one plate is located above and in close proximity to the next plate below. During operation, a strewn of oil bearing water is arranged to flow upwardly in contact with the corrugated or grooved undersides of each of the plates. Coagulated oil in the form of buoyant oil droplets break off the top edges of the plates and rise to the surface accumulation zone above. In the case of known tilted plate oil separators, it is customary to use the Stacked Plate packs with the plates inclined at an angle of 45 degrees to the horizontal. This inclination is said to maximise the effective separation surface area. The expression "effective separation surface ara' in this context relates to the horizontal component of the surface area of the inclined plates. Other angles of inclination can be effective, depending on the circumstances.

Serial Plate arrangement In this case, the tilted corrugated plates are arranged so as to act in sequence to promote the separation of oil from water. The sequence may be of single tilted corrugated plates. Alternatively, the sequence may include discrete tilted Stacked Plate units of two or more corrugated plates disposed so as to act in sequence along the line of the fluid flow between the inlet and the outlet of the separation chamber. The area where the droplets of oil separated out by the first tilted corrugated plate or by the first Stacked Plate unit accumulate to form a floating layer of oil is referred to for the purposes of this specification as "the first surface accumulation zon6". A barrier extending downwardly from above the fluid surface isolates the first surface accumulation zone from a second corresponding like zone which receives oil from the second tilted plate or tilted Stacked Plate unit. Likewise, each successive like surface accumulation zone in sequence is isolated by a barrier from its preceding surface accumulation zone. The barrier in each case directs the flow of water down to the vicinity of the base of the separation chamber. The water takes with it the oil that has not been left behind in the previous surface accumulation zone. The fluids flow under the barrier and then upwardly in contact with the downwardly facing corrugations of the next corrugated plate or Stacked Plate unit as the case may be. Oil that is separated out by the such corrugated plate or Stacked Plate unit rises to the surface of the next surface accumulation zone. The sequence is repeated as many times as may be deemed necessary or desirable to achieve the required degree of separation. Oil in progressively diminishing amounts accumulates in the successive surface accumulation zones. It is removed in the manner indicated below. Oil depleted water flows out of the separation chamber from below the surface of the last surface accumulation zone. Such water may then be passed through a filter matrix of a known kind to entrap very finely divided oil particles that have survived passage through the separation chamber.

Recovery of oil from the separation, chamber.

During operation, surface oil accumulates in a continuously thickening layer within the several surface accumulation zones. It may be scooped out or sucked out by conventional means.

In the preferred method of this application of the present invention, the oil is removed by making use of the "Density Differential" principle mentioned above. Within the several surface accumulation zones, or within certain selected zones, there are located oil removal pipe inlets leading onto downwardly extending oil removal pipes. As in the case of the setting of the respective levels of the weir rim of the downstream Tulip Valve and the rim of the oil removal pipe inlet within the vortex chamber, the respective levels of the weir rim of the Tulip Valve and of each oil removal pipe inlet rim within the separation chamber are set so that when water alone flows through the separation chamber, each inlet rim stands proud of the water surface level. Each inlet rim is also set at a level that is low enough to allow the oil to rise above its level when the thickness of the layer of accumulated oil in its particular zone attains a particular value. The thickness of the respective oil layers increases and the oil surface levels rise when oil contaminated water flows through the separation chamber. Oil eventually flows over the rims of the respective inlets and down through the oil removal pipes. See also the discussionabove under the heading "Removal in practice".

During the operation of the Serial Tilted Plate type separator, the oil accumulates in successive surface accumulation zones at successively slower rates. Eventually, the rate of accumulation in one or more downstream zones may become negligible so that it becomes impractical to rely on the Density Differential principle for an outflow of oil. It may be preferable to use an oleophilic rag, sponge or swab to remove it. Use of Oil Filters. Water that has flowed through the separation chamber will carry with it traces of residual oil in the form of very finely divided particles that are resistant to coagulation into droplets. At this stage, further oil separation may be carried out by passing the water through an oil adsorbent matrix filter, e.g. a porous polyurethane foam or polyurethane matted fibre matrix of the kind widely used in oil/water separators. Preferably, this is done by way of a downward flow. In the absence of an intermediate Tilted Plate separation chamber, the partly decontaminated water that flows from the vortex chamber may be passed directly through such an oil adsorbent matrix filter. Many oil/water separators in current use employ such matrix filters as the principal expedient whereby oil is separated from water. When the filters become saturated, they are re- constituted or replaced. This limits their utility where there is a high proportion of oil in the oil/water feed mixture. Steps have to be taken to recover the oil from the saturated filter matrices, and this inevitably involves effort and expense. On the other hand, when the method of the present invention is put to use, the filter matrix is called upon to deal with no more than a. where a Tilted Plate separator is used as indicated herein, the nearly negligible amount of very finely divided oil carried by the water after its passage through the separation chamber, or b. the residual oil present in the water flowing out of the vortex chamber where no intermediate Tilted Plate separator is used; and the frequency and cost of replacing or reconstituting the filter matrices is materially reduced. Use of "Lemer Plates". The present invention includes within its scope the use of a Tilted Plate separator as described in the specification of our co-pending United Kingdom Patent Application

No.GB 9922717.5. Such Tilted Plate separator comprises one or more of the particular corrugated or grooved plates which, in part, form the subject matter of that specification. For convenience, such plates are referred to herein as "Lemer Platee'.

Definition. A Lerner Plate is defined for the purposes of this specification as a corrugated plate for use in separating two masses of flowable matter having different specific gravities which comprises adjacent longitudinal grooves disposed between corresponding ridges, the depth of each groove being arranged to increase progressively simultaneously with a progressive decrease in the mean angle between the groove sides when proceeding along the one or other longitudinal direction.

For the purposes of this definition, the expression "the mean angle between the groove sides" means the angle between two lines, each extending upwardly from the same point on the base line of a groove, the one to the ridge line running along the ridge located on the one side of the groove and the other to the ridge line running along the ridge located on the other side of the groove, both lines as seen in plan view being disposed at right angles to the said base line.

The description of the Tilted Plate separator device and of the corrugated plates and, furthermore, the manner of their operation as set out in the last mentioned specification are incorporated in each case by reference into the present specification. Such description indicates and identifies the preferred Tilted Plate separators incorporating corrugated plates to be interposed between the vortex chamber and the Means A, (in particular, a Tulip Valve) for the removal of residual oil fi7om the partly decontaminated water outflow from the vortex chamber in this embodiment of the present invention.

Upstream Stabilisation.

Reference has been made above to an upstream stabilisation of the oil and water feed mixture following which the oil and water flow into the vortex chamber as two separate layers. Where there has been no stabilisation of this kind, and in cases other than Marine Applications, the manner of the sourcing and of the transference and/or delivery of an oil/water feed mixture to the vortex chamber can give rise to random irregularities in the rate of flow and to the transmission of disruptive elements within the flow. For example, direct pumping of an oil/water mixture can result in the transmission of turbulence, pulsations and/or vibrations which can be prejudicial to the formation of a stable and turbulence free floating oil vortex within the vortex chamber. The situation is aggravated when air is adn-fixed with the oil/water mixture. Such admixture is inevitable when the oil/water feed is drawn from a surface oil skimmer such as the MANTIS (T.M.) Skimmer described in our co-pending International Patent Application No. PCT/Gl3 99/01327. In this and in other cases, it becomes desirable to stabilise the flow before it enters the vortex chamber.

The present invention in its broadest scope includes the provision of upstream stabilisation means acting on the oil and water feed stream prior to its admission to the vortex chamber which includes:

i. a preliminary vortex chamber that contains flow diverting baffle or guide means that impart a rotational movement to the stream. In this connection, it is highly advantageous to make use of a Clock Spring Guide-, ii. optionally, a further chamber to receive the stream from the preliminary vortex chamber and which contains one or more baffle plates adapted to lie across the direction of flow of the stream. By the use of such stabilisation means, turbulence, pulsations and vibrations within or transmitted by the oil/water feed stream are diminished or eliminated. The placated stream will enter the vortex chamber to provide a smooth and turbulence free oil vortex floating on the water. Where the oil/water mixture is delivered by gravity flow alone, problems of the kind that are caused by an upstream pump seldom arise. The apparatus of the invention may be usually be worked satisfactorily without the addition of an upstream stabilisation chamber. The present invention also relates to a method in which each or any of the several embodiments of the apparatus of the invention as described herein is used to separate oil from water. Algae separation. According to an important further aspect of the present invention, the apparatus of the invention as described herein may be used for the purpose of separating floating algae from water. In this connection, the description herein insofar as it relates to the separation of oil from water is repeated, where the context so admits, so that the expression "floating algae" is substituted for the expression "oil" where it occurs.

Supplementary Tulip Valves and Sluice Gates.

In the case of any weir acting sluice gate referred to herein, including any Tulip Valve, there may be added to such a device one or a plurality of such devices all connected in parallel to the original source of liquid flow to the first device, but with the weir rim of the second and each subsequent device being set at a pre-determined level that is marginally higher than the level of the weir run of the preceding device in sequence. Such an arrangement provides means for accommodating unexpected or undesired surges in flow that might exceed the capacity of the first device or of the preceding devices in the sequence. In this connection, reference is made to the disclosure in the specification of our aforesaid co-pending United Kingdom Patent Application No. GB 9922369. 5.

The drawings.

The invention will now be described by reference to accompanying schematic drawings in which:

Figure I and Figure 2 represent in plan and cross sectional side view respectively a simple form of vortex oil separation system of the invention.

Figure 3 and Figure 4 represent in plan and cross sectional side view respectively the embodiment of the present invention in which a tilted corrugated plate separation chamber and a filter matrix chamber are interposed between i. the vortex chamber and ii. the Tulip Valve that constitutes the variable flow regulating means adapted to regulate the rate of flow of water through the vortex chamber as represented in Figures I and 2.

Figure 5 represents a "Lemee' corrugated plate for use in the tilted corrugated plate separator according to the preferred embodiment of this aspect of the invention.

Figure 6 represents a sectional side view of apparatus according to the embodiment of the present invention in which oil to be separated enters the vortex chamber as a discrete layer floating on water. Figure 7 represents a plan view of the apparatus of Figure 6.

Figure 8 represents a sectional side view of a modification of the apparatus of Figure 6 which comprises by-pass means and weir valve means for controlling the flow of water through the by-pass.

Figure 9 represents in plan view apparatus according to the present invention which is mounted for buoyant support between a pair of parallel adjacent hulls, one on each side and is provided with a pair of forwardly extending divergent booms to divert floating oil and a layer of surface water into the forward part of the apparatus. Rearwardly directed water propelling means in the form of a marine screw propellor is provided behind the final exit pipe for the water that has passed through the vortex chamber. By-pass conduits extend from the forward part of the apparatus upstream of the vortex chamber inlet to divert some of the water entering the forward part of the apparatus around the sides of the vortex chamber. Sluice gate valve means are provided to control respectively:

i. the rate of flow of water through the vortex chamber, and ii. the rate of flow of water through the by-pass means.

Figure 10 represents a sectional side view of the apparatus of Figure 9.

In Figures I and 2, 1 represents a vortex chamber which receives the feed mixture of oil and water to be separated through its inlet 2. A Clock Spring Guide having a wall member 3 that stands on a base 17 and which provides an helical path is located within the vortex chamber. An oil removal pipe 5 has its inlet 4 at a level above the wall member 3 and extends downwardly through the outlet aperture 16 in the base member 17 of the Clock Spring Guide. Around the upper part of pipe 5 and below the location of the bottom of the oil vortex is disposed a baffle plate 30 the function of which is to restrain the occasional tendency of the floating oil vortex to be distended downwardly with consequent breaking off of the lower parts of the vortex.

As shown in Figure 1, for the first near complete circuit, the helical path provided by wall member 3 proceeds between the vortex chamber inner wall and the outer wall of the helical wall member 3 of a Clock Spring Guide. Thereafter, the path proceeds between the opposing sides of the wall member to the zone surrounding the centre of the helix where there is located a liquid outlet aperture 16 in the base member 17. When the feed mixture enters the vortex chamber 1, it encounters the whirling mass of fluid whose rotation is generated and maintained by the combined effect of the tangential entry and the drag effect of the lower part of the water mass that flows along the helical path. Oil migrates upwardly and inwardly through the surrounding water by reason of its lower specific gravity. A centrally disposed floating oil vortex 13 is formed. As the continuous strewn of feed mixture brings additional oil into the vortex chamber, more oil joins the vortex 13. The oil vortex assumes the shape of an inverted bell-curve that spins around its axis. It floats above the helical wall member 3 of the Clock Spring Guide, supported by the rotating stream of water as the water progresses through the chamber to the outlet 16 in the base member 17. As it proceeds towards the outlet 16, the lower part of the swirling mass of water enters the spiral path of diminishing radius provided by the Clock Spring Guide. This adds impetus to its rotational motion. As a result, the water exerts a drag effect from below upon the overlying fluid layers. This, in addition to the effect of tangential entry sets up and maintains the rotational movement of all the fluid within the vortex chamber.

The level of the upper rim of the helical wall member 3 is progressively lowered in the direction of the zone surrounding the centre of the helix. This is done so as to accommodate the pendulous submerged portion of the oil vortex 13. The best results are obtained when the interface 6 between the oil vortex and the supporting water does not extend downwardly as far as the upper rim of the wall member 3.

The inlet 4 of a downwardly directed oil extraction pipe 5 is arranged to be located within the oil vortex. Preferably, the height of the rim of inlet 4 is made adjustable, e.g. by screw mounting the inlet 4 on to the oil extraction pipe 5. When the surface level of the floating oil vortex rises above the level of the rim of inlet 4, oil flows out of the vor-tex chamber through pipe 5.

Water flows out of the vortex chamber I through outlet 16 in the base member 17 of the Clock Spring Guide component. Outlet 16 may be supplemented by small peripheral outlets (not shown) located, preferably symmetrically in the base member 17. Their function is to discourage a distortion of the shape of the submerged oil vortex leading to a breakaway of oil from the vortex to join the outflow of water. Where use is made of such small supplementary outlets, most of the water flow nonetheless leaves the vortex chamber through the outlet 16.

The water may then, optionally, be passed through a stabilizing zone comprising one or more horizontal baffle plates disposed across the direction of its flow.

The water flows onwardly through pipe 7 into the weir valve arrangement constituted by the Tulip Valve chamber 8. Water fills the chamber 8 up to the level of the Tulip Valve weir rim 9. As more water enters chamber 8, a stream of water spills over the rim 9 and into the Tulip Valve outlet pipe 10.

Weir rim 9 forms the rim of the expanded opening I I of the downwardly extending pipe 12 which is mounted telescopically onto the outlet pipe 10. Upward and dow nward movement of the rim may be precisely controlled by providing a screw mounting as between the pipe 12 and the outlet pipe 10. Alternatively, use may be made of other means whereby longitudinal adjustment may be made to the relative positions of one pipe or tube telescopically mounted on another.

The level of the downstream weir rim 9 governs both the fluid level in the vortex chamber and the rate at which water flows through the vortex chamber.

The "Density Differential" principle for the removal of separated oil from the oil vortex is put into operation. (See discussion in the text above.) The weir rim 9 and of the rim of inlet 4 are respectively set at levels, the one in relation to the other which will ensure that when water alone flows through the chamber, the inlet rim stands proud of the water surface, but when the thickness of a floating layer of separated oil within the vortex chamber exceeds a particular value, oil will flow through the inlet 4 and out through the oil removal pipe 5. See also the matter set out in the text above under the heading "Removal in practice'.

Upstream stabilization.

Where necessary or desirable, an upstream stabilisation chamber 20 may be employed to dampen or eliminate disruptive turbulence, pulsations and/or vibrations transmitted from an upstream pump or the like which may be prejudicial to the stability and the smooth running of the separation process within the vortex chamber 1. In the embodiment of the invention described by reference to Figure I and Figure 2, the oil/water feed mixture on entering the stabilisation chamber 20 encounters a Clock Spring Guide arrangement whereby the feed stream is conducted along an helical path defined by the inner wall of the chamber 20 and the helical wall member 21 of the Guide before flowing downwardly through the base outlet aperture 22 into a lower chamber comprising one or more horizontal baffle plates 23 disposed across the direction of the flow. For this application, the upper rim of the wall member 21 maintains a constant height or else increases in height in the direction of the flow towards the central zone.

The use of the stabilisation chamber 20 provides self evident advantages in stabilising the flow of the oil/water mixture into the vortex chamber and in damping down turbulence, pulsations and/or vibrations in the feed mixture. As an alternative to a vortex chamber, upstream stabilisation may be effected as mentioned above by the gentle flow of the oil/water feed mixture along channels or conduits under and between horizontal or slightly tilted corrugated baffle plates with their corrugations disposed in the direction of the flow. Preferably, use is made of "Lerner Plates" as defined above disposed with their groove depths increasing in the direction of the flow.

In Figure 3 and Figure 4, a tilted corrugated plate separation chamber 40 and a filter matrix chamber 60 are interposed between the vortex chamber I and the Tulip Valve chamber 8 of Figure I and Figure 2 above. Elements or features represented in the drawings of Figure I and Figure 2 are numbered as in Figures I and 2, but with a suffix 'W' in each case so that the vortex chamber I and weir valve chamber 8 of Figures I and 2 become the vortex chamber I a and the weir valve chamber 8a in Figures 3 and 4, and so on.

In the preferred embodiment of the present invention, the construction and operation of the separation chamber 40 and of its associated tilted corrugated plates are as described in the Specification of our co-pending United Kingdom Patent Application No. GB 9922717.5 entitled "Corrugated Plate Separators". In the description provided by that Specification, the corrugated plates described and used are limited to "Lemer Plates". In other embodiments of the present invention, the tilted corrugated plates may include those commonly used in known tilted corrugated plate oil separators.

Referring to Figure 3 and Figure 4, water from the vortex chamber I a carrying with it a residual amount of oil enters the separator chamber 40 through inlet pipe 41 and impinges against the lower part of a downward facing side of a tilted grooved plate 42 extending from the base of the separation chamber upwardly to a level below the liquid surface. Its corrugations lie in the direction of the fluid flow. As the partially decontaminated water flows upwardly in contact with the downwardly facing corrugated side of plate 42, oil particles coagulate into droplets which, on reaching the upper edge of the grooved plate, break off and float to the surface. As the flow continues, the droplets accumulate to form a layer of floating oil 43. This layer is located within a zone 44 (the first surface accumulation zone) bounded by barrier 45. that extends downwardly from above the fluid surface, stopping short of the base of the separator chamber so as to provide a gap 46. Water together with the oil that has not been left behind in layer 43 is guided downwardly by the barrier 45 and passes through gap 46 to impinge against the lower part of the second tilted grooved plate 47. It then moves upwardly in contact with the grooves along the underside of the plate. Additional oil breaks off from the upper edge of tilted grooved plate 47 and rises to form a second floating oil layer 48 within the second surface accumulation zone 49. This process is repeated, mutatis mutandis, each time the fluid flow encounters a like combination of barrier plate and tilted grooved plate.

In Figure 5, 51 represents isometrically a "Lemer Plate" that has downwardly facing grooves 52, 53 and 54 and complimentary upwardly facing grooves 55 and 56. The outer plate edges 58 and 59, ridges 61, 62 and 63 and groove base lines when seen in plan view are arranged to be parallel to each other. The angle between the grooved walls decreases in the direction shown as "N'. At the same time, the height of the grooved walls (base line to ridge) increases in the direction shown by "A". When using Lerner Plates in a tilted plate oil separator, each plate is disposed so that the depth of the grooves progressively increases whilst the mean angle (as defined above) simultaneously decreases in the direction of the fluid flow. In the present instance, the partly decontaminated water will flow upwardly in contact with the undersides of the plates. Oil particles carried by the flow will rise towards the apices of the inverted grooves.

There, they are constrained to move along a path that becomes progressively more constricted. This promotes coagulation leading to the formation of the droplets that eventually break free from the upper edges of the plates and float to the surface.

(Although the Lemer Plate described by reference to figure 5 above is refer-red to and depicted as having parallel sides and ridges, the definition of a Lerner Plate at its broadest will include the case where the sides and ridges are not necessarily parallel.) The corrugated plate separator separates out all but a small proportion of the residual oil carried over by the flow of water from the vortex chamber. At each successive surface accumulation zone, the amount of oil left behind diminishes. The number of successive combinations of barrier and grooved plate, and hence of the surface accumulation zones will depend upon the degree of separation sought and the cost advantages or disadvantages of adding further barrier/grooved plate combinations. The limit may be reached when any of the oil that is still carried by the flow of water is in such a finely divided state as to call for other measures for further extraction. The thickness of the layer of the oil in the final oil separation zones, even after prolonged operation, may be no more than minimal. It may be possible in practice to remove such oil as may be present using oleophilic rags, swabs or sponges.

The respective surface fluid levels within the vortex chamber I a and within the several surface accumulation zones in the separation chamber 40 are all regulated and set by the level of the weir rim 9a of the Tulip Valve arrangement downstream.

Removal of oil from the separation chamber.

Within or leading out of the surface accumulation zones are oil removal pipe inlets. Each inlet leads to an oil removal pipe through which oil will flow away from the apparatus of the invention. In Figures 3 and 4, the inlets are represented schematically and for the purpose of explanation by sideways facing pipe elements 65, 66 and 67. In actual practice, however, it is preferred that the inlets be located within the respective surface accumulation zones facing upwardly and having vertically adjustable rim levels, e.g. as provided by screw threaded telescopic mounting on to their respective oil removal pipes. The respective levels of the oil removal inlet rims are set at a level that will enable the Density Differential principle referred to above to be applied to the removal of oil from the vortex chamber. That is, the height or heights of the fims of the respective inlets on the one hand and the height of the weir rim 9a of the downstream Tulip Valve on the other hand are arranged to be such that a) Where water alone flows through the system, the outlets stand proud of the water level, but b) Where a layer of oil accumulates within the surface accumulation zones or any of them, the fluid surface will rise. When the layer has become sufficiently thick, oil in each case will flow over the oil removal inlet rim provided for the zone in question and away through its associated oil removal pipe. See also the discussion under the heading "Removal in practice" above. As already indicated by reference to the embodiment of Figures I and 2, the fluid surface level within the vortex chamber is also regulated by the level of the weir rim of the downstream Tulip Valve. Thus the mechanism whereby the oil is removed from the separation chamber is the same, mutatis mutandis as the mechanism described above whereby oil is removed from the vortex chamber Ia. A twofold result, being the separation of oil using vortex means within a vortex chamber and, in addition, the separation of the removable residual oil flowing out of the vortex chamber is achieved by the use of Means A in conjunction with the application of the Density Differential principle. Figures 3 and 4 in addition disclose the interposition of a filter matrix chamber 60 between the separation chamber 40 and the weir valve arrangement in chamber 8a. By the time the flow reaches the filter chamber 60, no more than a minimal amount of oil may be carried by the water. The flow proceeds downwardly through the chamber 60. One or a series of filter elements 65 are disposed across the path of the flow to trap the very finely divided particles of oil that resisted capture within the separation chamber. The water is thus provided with its final "polislf. Since a very high proportion of the oil will already have been removed before the water enters the filter chamber 60, the cost and effort of replacing or refurbishing the filter elements is minimised. In the embodiment of the invention represented by reference to Figures 6 and 7, a stream of water 71 bearing a floating layer of oil 72 enters a vortex chamber 73. Gate 74 hinged at 75 opens to admit the layer of oil and a supporting upper layer of the water through the vortex chamber inlet. Horizontal plate 76 is connected to the lower edge of the gate 74 and moves partly into the interior of the vortex chamber when the gate is opened. The lower layer of the water enters through the lower part 77 of the vortex chamber inlet and continues along an horizontal helical path of diminishing radius provided by the inner wall of the chamber acting in conjunction with the helical wall member 78 of a Clock Spring Guide located within the chamber. A swirling fluid mass is thus formed in the chamber which includes a stable turbulence free vortex of floating oil 86 at its centre. The rate at which oil enters the vortex chamber to join the oil vortex may be controlled by the gate 74. (Gate 74 thus constitutes "Means D": see above. ) On shutting the gate 74, the oil accumulates in a thickening layer outside the vortex chamber. When the gate is opened, horizontal plate 76 serves as a baffle which helps to shield the floating oil on entry into the chamber from the disruptive effect of the rapidly rotating mass of water below.

The helical wall member 78 of the Clock Spring Guide stands on the base member 79 that is provided with an outlet aperture 87 which constitutes the vortex chamber outlet. Water flows downwardly through this outlet and through the conduit member 88 into a Tulip Valve arrangement contained in the chamber 80. The Tulip Valve weir rim 81 is set at a level that regulates the rate at which the water flows through the vortex chamber 73 and, in addition, the fluid surface level within the vortex chamber. Thus when no oil is present, the fluid surface level (of the water) as set by the weir rim 81 will be below the level of the rim of the inlet 82 to the oil removal pipe 83. But when a layer of oil of sufficient thickness floats on the water in the vortex charnber, the surface level of the floating oil will rise above the level of the rim of the inlet 82, and oil will flow into the oil removal pipe 83.

In this particular embodiment, the floating oil vortex 86 is connected to a separate Tulip Valve arrangement located in chamber 85. In this way, there is provided a further means for regulating the surface level of the floating oil in the vortex chamber together with means for regulating the rate at which oil is withdrawn from the floating vortex. C'Means C".)This is done by adjusting the level of the weir rim 89 of the Tulip Valve arrangement upwardly or downwardly as required. In the embodiment represented in Figure 6, the oil removal pipe 83 carries the oil from the oil vortex 86 to the chamber 85. Pipe 90 having an expanded end portion 91 that terminates with the weir rim 89 is mounted telescopically on to the outlet pipe 92. Oil from the oil vortex flows over the weir rim 89 and out through outlet 92. Water that accompanies the flow of oil from the vortex 86 separates out in chamber 85 and accumulates as a layer 93 at the bottom of the chamber whence it is periodically removed through outlet 94.

The rate of the flow of water through the vortex chaniber will respond to the surface fluid level in the chamber. Thus the Tulip Valve arrangement in the chamber 85 may constitute means for regulating such rate.

The arrangement of Figures 6 an 7 has proved particularly useful in the separation of oil from water where the oil/water feed had first been stabilised by passing it through an "horizontal flow" stabilisation stage which comprised the use of slow moving flow zones, baffles and a trough in which were located submerged, longitudinally disposed Lemer Plates as described by reference to Figure 5 tilted at a shallow angle. The original oil/water feed mixture came from a MANTIS (T.M.) Skimmer working in an industrial environment on the surface of a body of water covered by a coating of heavy waste oil Following such stabilization, the oil separated from the water and floated as a discrete layer on the surface of the water flow that entered the vortex chamber.

A vortex chamber arrangement as described by reference to Figures 6 and 7 is also ideally adapted for Marine Applications under stable conditions, e.g. where the apparatus is land based or securely mounted on stable buoyant support to receive a river, tide borne or induced flow of surface oil contaminated water.

Figure 8 represents a sectional side view of the embodiment of the invention as represented by Figure 6 to which has been added a by-pass conduit means that constitutes a "Means B", i.e., means adapted to regulate the flow of water through bypass means arranged to divert water that enters the forward part of the apparatus upstream of the vortex chamber away from the chamber. Save for such addition, Figure 8 replicates Figure 6; and for convenience, elements or features appearing in Figure 8 that also appear in Figure 6 are given the same numbering, but with the suffix "a".

In Figure 8, a by-pass conduit 100 leads from the lower levels of the mass of water 7 1 a in the forward part of the apparatus upstream of the vortex chamber 73 a to chamber 10 1 that houses a Tulip Valve. During operation, water flows through the conduit 100 into chamber 10 1 where it spills over the weir rim 102 of the Tulip Valve into the exit pipe 103. The level of the rim 102 of the Tulip Valve, if acting alone, win regulate the rate of flow of the water through the by-pass conduit 100 and., in addition, the fluid surface level above the water 71 a which, in turn will influence the fluid surface level in the vortex chamber 73a. Figure 8 thus represents embodiments of each of the Means A to D. Means A and Means C are represented respectively by the Tulip Valve arrangements in chambers 81a. and 85a, and Means D by the gate 74a. Means B is represented by the Tulip Valve arrangement in chamber 10 1.

Where two or more flow control means are put to work in a fluid system as represented by Figures 6, 7 and 8, the operation of the one will inevitably have an effect upon the operation of one or more of the others. Taking for example the embodiment of Figure 8, an increase in the flow through the by-pass conduit 100 regulated by Means B could lower the fluid surface level of the water 71a immediately upstream of the vortex chamber. This in turn, acting alone will reduce the rate of gravity induced flow into and through the vortex chamber unless compensated, (in the circumstances, possibly temporarily) by a lowering of either or both of the relevant Tulip Valve weir rims in chambers 80a and/or 85a and/or the opening of gate 74a. Likewise, any variation of the flow regulated by any or more of the other Means will affect the overall operation of the system. It is the task of the operator to adjust and set the relevant weir rim levels and the gate opening so as to secure optimum operation of the apparatus of the invention in any particular circumstances. In the course of practical operations, satisfactory settings for coping with the different circumstances that arise are arrived at by trial and error. By way of example, the periodic adjustments and settings of Means B could be crucial factors in Marine Applications where the relative forward speed of the apparatus in relation to the incoming flow of surface oil bearing water and/or the thickness of the oil layer can vary unpredictably. Such variations will also have an important bearing on the necessary settings of each of the other Means A, C and D. On the other hand, in a stable industrial environment not subject to unpredictable changes in operational circumstances, satisfactory performance may be secured by the adjustment and setting of Means A, C and D only.

The above considerations will apply, mutatis mutandis, in the case where one or more of the fluid flow regulating arrangements referred to by reference to the drawings is replaced by another suitable fluid flow regulating valve arrangement.

Figures 9 and 10 represent an arrangement in which apparatus according to the present invention is buoyantly supported in a partly submerged state between two parallel hulls or booms I 10 and I I I for removing floating oil from a body of water. A pair of forwardly extending divergent booms 115 and 116 are arranged to divert oil bearing water into the forward part of the apparatus. The arrangement may be anchored facing upstream in a river or tidal flow. In static water, fluid flow through the apparatus is induced by rearwardly directed water propulsion means 112. In general, such means may be employed:

i. To augment or induce the flow of oil bearing surface water into the forward part of the apparatus between the forwardly extending divergent booms 115 and 116, and, additionally, ii. Where required, as propulsion means for driving the buoyantly supported apparatus forwardly over a body of surface oil contaminated water.

The apparatus of Figures 9 and 10 comprises a vortex chamber 113 that is provided with an inlet 114 through which flows the oil bearing upper layer of a stream of water that has been diverted by the boom arms 115 and 116. Downstream of the boom arms, a fixed barrier plate 13 5 is mounted across the base 120 of the forward part of the apparatus. This plate allows entry into the apparatus of the oil bearing upper layer of water 136 only from the outer body of water. Slidable gate valve plates 117 and 118 are located adjacent the base 120 of the forward part of the apparatus upstream of the vortex chamber inlet 114 and well below the water surface level 121 when the apparatus is buoyantly mounted for operation.. They are adapted to close and open their respective associated apertures 119 and 132 that lead respectively to by-pass conduits 13 3 and 134. They may be operated manually or else by means that respond to fluid surface levels in the forward part of the apparatus and/or within the vortex chamber.

The apparatus of Figures 9 and 10 is adapted to separate floating oil from water. Hence, if desired, and dependent upon the circumstances, the particular features relating to regulation of flow through the vortex chamber inlet that characterise the embodiments of Figures 6, 7 and 8 above (including Means D) may, but need not be added to the Figures 9 and 10 embodiment.

Within the vortex chamber 113 of this embodiment, a combination of tangential entry and the influence of the helical wall member 122 of the Clock Spring Guide results in a rotating fluid mass within which the oil separates out to float as a vortex 123 on the surface of the water. Water escapes from the vortex chamber through the base outlet 124 of the Clock Spring Guide incorporated within and forming part of the vortex chamber. An oil removal pipe 125 has its inlet 137 adapted to be immersed in floating oil vortex 123 and extends downwardly through the outlet 124 and then through the lower chamber 127 located below the vortex chamber.. On leaving the vortex chamber through outlet 124, the water flows into the lower chamber 127 and then rearwardly through the lower chamber outlet 128 into exit conduit 129 that leads to the rear outlet 130 of the apparatus.. The rate of water flow through the vortex chamber is regulated by a gate valve which comprises a vertically slidable plate 126 adapted to control flow through the outlet 128. Gate valve plate 126 may be operated manually or else by means that respond to the fluid surface levels in the forward part of the apparatus and/or within the vortex chamber. Rearwardly directed water propelling means such as a screw propellor 112 of an outboard engine is mounted behind the rear outlet 130. Alternatively, the propellor may be mounted for static operation within the conduit 129 upstream of the outlet. By impelling rearwardly the flow of water that has passed through the apparatus, it sets up or augments the inward flow of replacement water. In non static operations, it drives the buoyantly supported apparatus forward.

The slidable gate valve plates 117 and 118 control entry of water into their respective associated apertures 119 and 132 leading to by-pass conduits 133 and 134 respectively. Both conduits are adapted to carry water from the forward part of the apparatus past the vortex chamber to the junction of each with the conduit 129 where such water is joined by the flow from the outlet 128 of decontaminated water that has passed through the 41- vortex chamber 113. The combined flows make their exit through the exit conduit 129. During operation, the by-pass arrangement brings Means B into play. The fluid surface level in the forward part of the apparatus between the forward barrier plate 135 and the inlet 114 to the vortex chamber is regulated by the sluice gate valve means operated by reference to slidable plates 117 and 118. In the face of a continuous oncoming feed stream, the level will be raised by restricting access to the by-pass means, and vice versa. The fluid surface level within the vortex chamber 113 will respond to the fluid surface level in the forward part outside the inlet 114. Raising such fluid surface levels results in an increase in the rate of flow through the vortex chamber, and vice versa. Simultaneously, Means A is available by way of the downstream sluice gate valve means operated by reference to slidable plate 126 that controls aperture 128.. The separated oil is drawn from the oil vortex through the oil removal pipe 125 for temporary storage in floating storage bags or container tanks or the like.

The present invention has no moving parts. It provides an economical and adaptable system for the separation of oil from water in several different contexts ranging from heavy industrial applications in an hostile environment to light commercial applications in, for example, local garages, parking areas, factory basements and other places that promise to be subject to increasingly demanding environmental controls. For large scale operations, several units are connected to work on the contaminated flow in parallel, and advantage is taken ofthe larger working surface area and enhanced capacity provided by the "Stacked Plate7 arrangement referred to above.

In Marine Applications, the invention provides light, transportable, economical and effective means for recovering floating oil. The mobile embodiment, i.e. the embodiment adapted to be propelled forwardly by an outboard engine or the like is ideally suited for operation under radio and/or electronically programmed control. A large area of surface contaminated water can be readily, expeditiously and efficiently treated. The running costs will amount to little more than those of providing and running a simple marine outboard engine.

Claims

1. Apparatus for separating oil ftom water which comprises:

(i) a vortex chamber adapted to admit through an inlet a flow of oil and water; (ii.) means adapted to impart a rotational movement to the admitted oil and water so as to form within the chamber a rotating fluid mass within which a non-turbulent vortex of oil floats on the water; (iii.) means for the removal of oil from the oil vortex; (iv.) outlet means adapted to be located below the level of the floating oil for the escape of water from the vortex chamber, and (v.) variable flow regulating means located at or downstream of the outlet means and adapted to regulate the rate of flow of water through the chamber.

2. Apparatus for separating floating oil from water which comprises:

(1) a forward part adapted to receive a flow of water that bears a floating layer of oil-, (2) a vortex chamber located downstream of the forward part adapted to adn-fit through an inlet an upper layer of the flow of water together with the layer of oil that floats on such upper layer; (3) means adapted to impart a rotational movement to the admitted oil and water so as to form within the chamber a rotating fluid mass within which a non-turbulent vortex of oil floats on the water; (4) means for the removal of oil from the oil vortex; (5) outlet means adapted to be located below the level of the floating oil for the escape of water from the vortex chamber; (6) by pass means having inlet means in the said forward part adapted to admit water from below the oil/water interface upstream of the vortex chamber inlet and to divert the admitted water past the vortex chamber, and (7) variable flow regulating means adapted to regulate the rate of flow of water through the by pass means.

3. Apparatus as claimed in claim I that comprises in addition the features fisted by reference to the designations (1), (2), (6) and (7) in claim 2 above.

4. Apparatus as claimed in any preceding claim that comprises variable oil flow regulating means adapted to regulate the flow of oil on its removal from the oil vortex.

5. Apparatus as claimed in either of claims 2 or 3 or, insofar as it is dependent upon claim 2, claim 4 which comprises a vortex chamber inlet variable flow regulating means controlling the upper part of the vortex chamber inlet and adapted to regulate the flow of floating oil into the vortex chamber.

6. Apparatus as claimed in claim 5 in which the vortex chamber inlet variable flow regulating means comprises an hinged gate adapted to extend across the upper part of the vortex chamber inlet and opening to admit fluid flow into the vortex chamber.

7. Apparatus as claimed (a) in claim I and any later claim insofar as it is dependent on claim I wherein the variable flow regulating means listed as "(v.)", and/or (b) in claim 2 and any later claim insofar as it is dependent on claim 2 wherein the variable flow regulating means listed as "(7)". and/or (c) in claim 4 wherein the variable oil flow regulating means comprises in each or any case a sluice gate means.

8. Apparatus as claimed in claim 7 in which the sluice gate means comprises variable height weir means.

9. Apparatus as claimed in claim 8 in which the sluice gate means comprises a Tulip Valve as herein defined.

10. Apparatus as claimed A. in claim I and its dependent claims wherein the means adapted to impart rotational movement to the admitted oil and water fisted as "(ii. y', or B. in claim 2 and its dependent claims wherein the means adapted to impart rotational movement to the admitted oil and water listed as "(3y' comprises a Clock Spring Guide as herein defined.

11. Apparatus as claimed in any preceding claim which includes flow stabilising means adapted to act on the flow of oil and water upstream of the vortex chamber.

12 Apparatus as claimed in claim I I in which the flow stabilising means comprises a Clock Spring Guide as herein defined.

13. Apparatus as claimed in any preceding claim wherein the means for the removal of oil from the oil vortex comprises an oil removal pipe having its inlet adapted to be located within the floating oil vortex when formed.

14. A modification of the apparatus as claimed in claim 13 insofar as claim 13 is dependent on claim I wherein the oil removal pipe has its inlet rim adapted to be located at a level that is close to but above the surface level of the water within the vortex chamber as controlled by the variable flow regulating means mentioned in claim I when water alone flows through the chamber so that, during operation, upon the elevation of the fluid surface level within the vortex chamber accompanying the accumulation of oil within the floating oil vortex, oil flows over the rim into the oil removal pipe.

15. Apparatus as claimed in any preceding claim insofar as the same is dependent on claim I which includes means located along the path of flow between the vortex chamber outlet and the downstream variable flow regulating means for the removal of residual oil carried by the water emerging from the vortex chamber.

16. Apparatus as claimed in claim 15 in which the means for the removal of residual oil includes a tilted plate separator comprising one or a plurality of tilted corrugated plates located in a separation chamber.

17. Apparatus as claimed in claim 16 in which the fluid surface levels in both the vortex chamber and the separation chamber are regulated by the downstream variable flow regulating means.

18. Apparatus as claimed in claim 17 in which the corrugated plates are Lerner Plates as defined herein.

19. Apparatus as claimed in claim 18 in which the tilted plate separator amounts to apparatus substantially as described in the specification of our co-pending United Kingdom Patent Application No. 9922717.5.

20. Apparatus as claimed in any of claims 16 to 19 in which the tilted plate separator comprises oil removal pipes having their inlet rims adapted to be located at a level that is close to but above the level of the water within one or more surface oil accumulation zones in the separation chamber as controlled by the downstream variable flow regulating means when water alone flows through the chamber so that, during operation, upon the 45- elevation of the fluid surface level in any zone accompanying the accumulation of separated oil within such zone, oil flows over the rim into its associated oil removal pipe.

21. Apparatus as claimed in claim 20 in which the level of the inlet rims is vertically adjustable.

22. Apparatus as claimed in any of claims 17 to 21 in which the downstream variable flow regulating means comprises a Tulip Valve as defined herein.

23. Apparatus as claimed in any preceding claim which includes in the line of flow downstream of the vortex chamber filter matrix means adapted to separate fine particles of oil from the flow.

24. Apparatus as claimed in claim 23 insofar as it is dependent on claim 16 wherein the filter matrix means is located downstream of the separation chamber.

25. Apparatus for the separation of oil and water as claimed in any of claims I to 8 and, insofar as they are dependent on such claims, any of claims 10, 13 and 14 adapted to be partially immersed in a body of water so as to adrnit fluid flow into the vortex chamber.

26. An arrangement that comprises apparatus as claimed in claim 25 together with water impelling means located downstream of the vortex chamber outlet that is adapted to draw water out of the outlet.

27. An arrangement as claimed in claim 26 that is adapted to be buoyantly supported on a body of water with the water impelling means adapted to propel the arrangement through the water with the vortex chamber inlet facing the direction of movement.

28. An arrangement as claimed in either of claims 26 or 27 wherein the water impelling means is a marine outboard engine.

29. A method of separating oid from water using i. apparatus as claimed in any of claims I to 25 and 29, and/or ii. an arrangement as claimed in any of claims 26 to 29.

29. Apparatus and arrangements of the invention as claimed herein substantially as described by reference to the accompanying drawings.