CN116888326A - Filter device for collecting debris from the surface of a body of water - Google Patents

Abstract

The invention relates to a filtering device comprising: -a conduit (11) intended to be immersed in a fluid flow, and-a filter (14) arranged in the conduit and extending over the entire cross-section of the conduit, the conduit comprising an inlet opening (12) receiving the fluid flow and an outlet opening (13), the conduit comprising a downstream section (11 b) conveying the fluid flow exiting the filter towards the outlet opening, the surface area of the outlet opening being smaller than the surface area of the inlet opening, these surface areas being in a plane perpendicular to the longitudinal axis (X) of the conduit.

Description

Filter device for collecting debris from the surface of a body of water

Technical Field

The present invention relates to the collection of solid debris floating at or near the surface of bodies of water such as oceans, rivers and lakes.

Background

Many solutions have been proposed. Generally, these solutions consist of autonomous devices dedicated to collecting floating waste. Such devices include their own propulsion means, making them expensive to manufacture, operate and maintain.

An apparatus capable of being towed by a vessel is also presented. Such a device is described, for example, in patent EP 2 812 498. The apparatus includes a conduit positioned at the surface of the body of water along the direction of travel of the vessel. The conduit has a width that increases from the inlet of the conduit to the inlet of the filter in an attempt to reduce the resistance of the filter, thereby limiting excessive energy consumption of the vessel due to the presence of equipment towed over the surface of the body of water. The disadvantage of this device is that it can only be used at low speeds of less than 2m/s, in particular in order to maintain its ability to direct the incoming fluid towards the filter. It proves unsuitable for equipping vessels that normally travel at speeds greater than 2 m/s. Furthermore, at such speeds, the resistance introduced by the ducts arranged around the filter may exceed the resistance of the filter.

In particular, it was found that the greater the extent to which the velocity of the water surrounding the fluid is reduced in order to reduce the resistance of the filter, the more the resistance of the guide elements surrounding the filter increases.

Disclosure of Invention

It is therefore desirable to provide a filtration apparatus that effectively collects waste from the surface of a body of water without the need for a propulsion device. It is also desirable to increase as much as possible the ratio between the flow rate of the filtered water and the resistance generated when the filtering device is towed in the submerged state. It is also desirable that the filter device can be equipped with any vessel and can therefore be driven at speeds of more than 2 m/s. For this reason, the apparatus needs to be able to withstand the impact of waves travelling at high speed and to prevent large waste that may clog the filter inlet.

Some embodiments relate to a filtration apparatus comprising: a pipe intended to be immersed in a fluid flow, and a filter arranged in the pipe to filter the fluid entering the pipe, the pipe comprising: an inlet opening receiving the fluid flow, an upstream section extending from the inlet opening and accommodating the filter, an outlet opening, and a downstream section extending from the filter up to the outlet opening to convey the fluid flow exiting the filter toward the outlet opening, the downstream section having a length greater than or equal to the length of the upstream section, the outlet opening having a surface area less than a surface area of the inlet opening, the surface areas being surface areas in a plane perpendicular to a longitudinal axis of the conduit.

According to one embodiment, the upstream section has an internal profile in a plane passing through the longitudinal axis of the pipe, the internal profile being oriented towards the longitudinal axis of the pipe at an angle of zero or 0 ° to 16 ° to the direction of fluid flow.

According to one embodiment, the duct has a protrusion on its outer surface surrounding the inlet opening, the protrusion having a tangent at the inlet opening, the tangent being at an angle of more than 45 ° with respect to the longitudinal axis of the duct.

According to one embodiment, the downstream section has a straight or curved inner profile in a plane passing through the longitudinal axis of the pipe, which inner profile is at an angle of 0 ° to 20 °, preferably at an angle of 4 ° to 9 °, to the direction of the fluid flow.

According to one embodiment, the surface area of the outlet opening is tailored such that the velocity of the fluid flow at the outlet of the conduit is 80% to 110% of the velocity of the fluid around the outlet opening.

According to one embodiment, the surface area of the outlet opening is 0.1 to 5 times the total fluid passing surface area through the filter.

According to one embodiment, the cross-section of the conduit is circular, oval, trapezoidal, triangular, polygonal, square or rectangular in shape, or a shape consisting of these shapes.

According to one embodiment, the device comprises a grille positioned in front of the filter and having a fluid flow through surface area greater than that of the filter, the grille being positioned in the duct, or in front of the opening of the duct, so as to act as a filter and/or breakwater, the grille being potentially associated with a cleaning or suction device for removing debris captured by the grille.

According to one embodiment, the device comprises at least one filter having one of the following features: the filter has a conical or pyramidal shape; the filter has a conical or pyramidal shape and a debris discharge opening at the apex of the conical or pyramidal shape; the filter is planar and arranged perpendicular to the longitudinal axis of the conduit; the filter is planar and is arranged obliquely with respect to the longitudinal axis of the duct; the filter has a plurality of juxtaposed grooves having a V-shaped cross-section; each face of the filter has a convex portion and a concave portion; the filter consists of parallel rods; and the filter comprises rods or mesh whose profile is such as to reduce the resistance of the filter.

According to one embodiment, the filter is associated with a cleaning device or a suction device to remove debris captured by the filter.

According to one embodiment, the device includes a member configured to push the device upward when the device is fully immersed in the water, and a member configured to push the device downward when the device is not fully immersed in the water.

Some embodiments may also relate to a method for collecting solid debris near a surface of a body of water, the method comprising the steps of: providing a filter apparatus as described above and associating the filter apparatus with a structure that holds the pipe of the filter apparatus immersed in a water flow at a water surface or associating the filter apparatus with a vessel to hold the pipe of the filter apparatus immersed at a water surface and moving the vessel at a cruising speed to produce a water flow within and around the pipe of the filter apparatus.

According to one embodiment, the method comprises the steps of: the debris is collected in a reservoir.

According to one embodiment, the water flow has a velocity of 1m/s to 15m/s.

Drawings

Exemplary embodiments of the invention will now be described, without limitation, with reference to the accompanying drawings, in which:

figure 1 depicts a filter device according to one embodiment in a longitudinal section in a vertical plane,

figure 2 is a perspective view of a filter apparatus according to another embodiment,

figure 3 is a longitudinal cross-sectional view of the filter apparatus of figure 2 in a vertical plane according to one embodiment,

fig. 4 is a longitudinal sectional view of a filter of the filtering apparatus according to one embodiment, fig. 4A is a detailed sectional view of a portion of the filter shown in fig. 4,

figure 5 is a perspective view of a filter apparatus according to another embodiment,

figure 6 is a longitudinal cross-sectional view of the filter apparatus of figure 5 in a vertical plane according to one embodiment,

figure 7 is a longitudinal cross-sectional view of a filter device according to another embodiment in a vertical plane,

figure 8 is a perspective view of a filter apparatus according to another embodiment,

figure 9 figures 9A and 9B are longitudinal cross-sectional views of the filtration apparatus of figure 8 in a vertical plane and a horizontal plane according to one embodiment,

figure 10 is a perspective view of a filter of a filtering apparatus according to another embodiment,

fig 11A and fig 11B are a top view in a horizontal plane and a longitudinal cross-sectional view in a vertical plane of a filter device according to another embodiment,

fig 12 fig 13 fig 14 fig 12-14 are longitudinal cross-sectional views in a vertical plane of a filter apparatus according to various other embodiments,

fig. 15 fig. 16 fig. 15 and 16 are longitudinal sectional views in a vertical plane of a filtering apparatus according to the related art.

Detailed Description

Fig. 1 depicts a filtration device 10 according to one embodiment. The apparatus 10 comprises a filter 14 arranged in a tubular duct 11, the tubular duct 11 comprising an upstream section 11a and a downstream section 11b, the upstream section 11a delivering a fluid flow to be filtered and having entered through an inlet opening 12 of the duct, the downstream section 11b delivering a filtered fluid flow towards an outlet opening 13 of the duct. A filter 14 is disposed in the conduit between the upstream and downstream sections for receiving a fluid flow to be filtered.

The filter device 10 may be immersed in a fluid stream, for example, towed or pushed under the surface 1 of a body of water, or fixed under the surface of a waterway. It may be noted that only the inlet opening 12 of the device may be immersed, the longitudinal axis X of the device 10 being maintained at an angle of less than 25 ° with respect to the surface 1 of the water.

According to one embodiment shown in fig. 1, the upstream section 11a defines an interior volume of cylindrical shape having a cross-sectional area that remains constant between the inlet opening 12 and the inlet of the filter 14. Thus, the total surface area of the filter may be the same as the surface area of the inlet opening 12. The downstream section 11b defines an internal volume of frustoconical shape having an internal cross-section narrowing from the outlet of the filter 14 to the outlet opening 13. The interior volume of the downstream section may have other shapes, such as the shape of a hyperboloid of revolution.

The outer surface of the duct 11 may have a convex profile widening from the inlet opening 12 around the inlet opening 12. The raised profile has a tangent T1 to the edge of the opening 12, which tangent T1 converges towards the plane of the opening, that is to say, the tangent T1 forms an angle θ with the longitudinal axis X of greater than 45 °, preferably greater than 65 °. At the junction between the upstream section 11a and the downstream section 11b, the profiles of these sections have the same tangent. It can be noted that such a profile creates a resistance in a direction opposite to the direction of flow 2, that is, such a profile facilitates movement of the device through the fluid flow. In the example of fig. 1, such a raised profile widens along the length of the upstream section 11a up to about midway and then narrows up to the outlet opening 13. According to one embodiment, the ratio between the length of the inner profile and the length of the outer profile of the upstream section 11a is 0.7 to 1.0. The bulge thus formed increases the length of the path taken by the fluid and thus increases the velocity of the fluid around the upstream section 11 a. As a result, the pressure around the upstream section 11a decreases, thereby creating positive resistance. This then gives the tubular conduit 11 better hydrodynamic properties, whatever the velocity of the fluid in and around the conduit.

According to one embodiment, the upstream section 11a has a curved or rectilinear internal profile in a plane passing through the longitudinal axis X of the duct, at an angle of 0 ° to 16 °, preferably at an angle of 4 ° to 9 °, to the direction of fluid flow. These features help to reduce the resistance acting in the direction of flow 2.

According to one embodiment, the downstream section 11b has a rectilinear or curved internal profile in a plane passing through the longitudinal axis X of the duct 11, the internal profile being at an angle α of 0 ° to 20 ° to the direction of fluid flow.

According to one embodiment, the downstream section 11b comprises a section 11c, the section 11c having a circular internal cross-section, the downstream end of which defines the opening 13. The internal cross-section of the section 11c is dimensioned such that the edges of the opening 13 taper. The transition region between the frustoconical inner portion of the downstream section 11b and the cylindrical inner portion 11c may have a rounded outer profile in order to delay the possible separation of the fluid from the outer wall of the pipe 11 in this region.

According to one embodiment, the surface area of the outlet opening 13 is defined such that the fluid velocity at the outlet of the duct 11 is 80% to 110%, preferably equal to 100%, of the fluid velocity around the outlet opening 13. In this way, the shear stress occurring at the interface between the fluid exiting through the outlet opening 13 and the fluid outside the pipe is reduced, so that the resistance exerted on the pipe 11 can be reduced. The surface area of the outlet opening 13 can be tailored by varying the length of the downstream section 11b and varying the angle α. Furthermore, the speed of the fluid flow in the pipe depends on the characteristics of the filter, in particular on its resistance coefficient. The lower the coefficient, the more the length of the downstream pipe 11b can be reduced, and this also reduces the resistance of the downstream pipe. In addition, the lower the coefficient of resistance of the filter, the higher the velocity of the fluid through the filter can be. Thus, the outlet opening 13 may be larger.

The filter 14 has pores or cells through which fluid may flow. Hereinafter, "through surface area" of a filter refers to the sum of the surface areas of the pores or cells of the filter. According to one embodiment, the surface area of the outlet opening 13 is smaller than the passing surface area of the filter 14 in order to reduce the difference between the fluid velocity at the outlet 13 of the duct 11 and the fluid velocity around the duct outlet.

The surface area of the outlet opening 13 may be 0.1 to 5 times the surface area of the fluid passing through the filter 14, depending on the characteristics of the filter.

The mesh of the filter may be defined by wires of circular cross-section. According to one embodiment, the wires defining the mesh of the filter have a hydrodynamic profile (lower drag coefficient) against the direction of the (face intro) fluid flow 2, as shown in fig. 4A.

According to the embodiment shown in fig. 2 and 3, the filtering device 10 comprises a grating 17 (or gratings 17) positioned in front of the filter 14 to prevent oversized debris from entering the duct 11 and reaching the filter and to guide the debris towards a debris reservoir 22, which debris reservoir 22 may be fixed above the duct 11. The grille 17 comprises parallel bars which are inclined at the top towards the rear of the duct 11 up to the inlet of the reservoir 22 so that the debris can be driven towards the reservoir 22 by the fluid flow 2. For this purpose, the duct 11 has an upper opening 26, through which upper opening 26 the rods of the grille 17 pass. The grille 17 may have a fluid flow passing surface area that is greater than the passing surface area of the filter 14. According to one embodiment, the bars forming the grille 17 have a hydrodynamic profile so as to minimize the resistance caused by these bars under the action of the fluid flow 2.

According to one embodiment, profiled elements 27 intended to act as breakwaters and deflectors to divert large debris are held across the inlet opening 12 by the rods 23. The profiled element 27 may have a hydrodynamic profile in order to limit its resistance.

According to one embodiment shown in fig. 3 and 4, the filter 14 has a conical shape with an axis substantially coinciding with the axis X of the duct 11. The filter 14 has an opening at the apex of its conical shape, which is positioned downstream in the duct 11 and opens into the duct 24. The shape of the filter 14 allows the collected debris to be transported towards the conduit 24 by the flow of fluid through the filter. According to one embodiment, the discharge conduit 24 leads to the debris collecting reservoir 21, and the debris collecting reservoir 21 may be secured above the conduit 11. The conduit 24 may be arranged such that fluid flow entering the conduit 11 and then entering the conduit 24 carries debris into the reservoir 21 or the reservoir 22 forming a single reservoir positioned or secured over the conduit 11.

According to one embodiment shown in fig. 1 to 3, the inlet opening 12 is centered on the longitudinal axis of the duct 11. In the example of fig. 1, the duct 11 has a rotational symmetry about its longitudinal axis X (if the opening 26 is omitted).

Furthermore, when considering the convex shape of the profile of the upstream section 11a and the frustoconical shape of the downstream section 11b, each angular sector of the duct 11 (around the longitudinal axis X of the duct) has a tendency to exert a thrust force towards the outside of the duct in a direction perpendicular to the inner surface of the duct. When the pipe 11 is completely immersed in the fluid, the thrust exerted by the various sections of the pipe are balanced against each other. In contrast, when, for example, the upper part of the pipe 11 emerges from the fluid, this equilibrium is lost, since the upper part region of the pipe no longer exerts an upward thrust. As a result, the lower section of the pipe has a tendency to drive the pipe 11 down to the fully immersed position.

According to one embodiment, the upper portion of the duct 11 is longer than the lower portion thereof. Therefore, since the thrust exerted by the upper portion of the pipe is greater than the thrust exerted by the lower portion of the pipe, the pipe has a tendency to rise above the water surface. When the pipe portion is exposed, the pipe has a tendency to fall back below the water surface because the lower portion of the pipe exerts a greater thrust than the exposed upper portion of the pipe. Thus, the pipe is automatically kept near the water surface. This effect can also be obtained by adjusting the convexity of the upper part of the upstream section 11 a. This effect can also be obtained using fins (fins 19 in fig. 2) fixed to the outer surface of the pipe, to the top of the pipe, to the front or rear of the pipe, or to each side of the pipe 11 in order to maintain the immersion, and oriented so as to exert an upward thrust force that is less than or equal to the downward thrust force exerted by the pipe when immersed only partially.

Fig. 4 depicts a filter 14 according to one embodiment. The conically shaped filter 14 is associated with a cleaning device 15, which cleaning device 15 comprises a brush configured to brush the mesh of the filter 14 and to rotate itself around the longitudinal axis of the filter 14, so that the debris is driven towards the vertex of the conical shape to enable the debris to be removed via the duct 24 under the influence of the fluid flow. The thrust of the fluid flow through the filter can be used to drive the rotation of the brush.

According to another embodiment, the cleaning device is stationary, while the filter 14 rotates about its longitudinal axis. Removal of debris toward the conduit 24 may be accomplished or facilitated by applying vibration to the filter.

According to another embodiment, the filter has a protrusion formed in the recess on the side opposite to the direction of the fluid flow. Thus, the filter may present a frustoconical portion having a large base and a small base, the small base being coupled to an end of the conical shape, the apex of the conical shape extending towards the large base of the frustoconical shape. Thus, in a plane perpendicular to the plane containing the large base of the frustoconical portion and passing through the apex of the conical shape, the filter has a W-shaped cross section.

Fig. 5 and 6 depict a filter device 30 according to another embodiment. The filter device 30 differs from the filter device of fig. 2 in that the filter device 30 comprises a duct 31 of rectangular cross-section, the duct 31 having an inlet opening 32 and an outlet opening 33 of rectangular shape. Filter 14 is replaced by filter 34. The filter 34 may be associated with a cleaning device 35 in the form of a roller brush that moves between a lower portion and an upper portion of the filter 34 to urge debris on the filter towards the reservoir 21'.

The filter device 30 may further comprise a set of parallel rods 37, which set of parallel rods 37 is fixed in the duct 31 between the inlet opening 32 and the filter 34. The rod 37 is able to remove large debris towards the reservoir 22' positioned above the duct 31. For this purpose, each bar 37 has an inclined portion in front of the opening 32 of the duct 31, so that the upper portion of the bar is closer to the downstream of the duct 31 than the lower portion of the inclined portion of the bar. Thus, debris captured by the rod 37 may be diverted upward into the reservoir 22' by the fluid flow. For this purpose, the duct 31 has an upper opening 26', through which the rod 37 can pass through the upper opening 26'. The stem 37 may have a fluid flow through surface area that is greater than the filter's through surface area. The stem 37 may, for example, have a fluid flow through surface area greater than 70% of the positive cross-sectional area of the conduit. According to one embodiment, the profile of the rods 37 is such that they minimize the resistance they cause under the action of the fluid flow 2.

According to one embodiment, the profiled element 27', which is intended to divert very large fragments, is held by the rod 23' in front of the inlet opening 32.

According to one embodiment, a rod 37 is also associated with the cleaning device 36, which cleaning device 36 moves along the rod in order to expel debris towards the reservoir 22'.

According to one embodiment, the rod has a hydrodynamic profile against the direction of the fluid flow 2.

According to one embodiment, the duct 31 is associated with lateral fins 39, the lateral fins 39 being arranged so as to keep the duct 31 just below the surface 1 immersed in the fluid, as shown in fig. 5. Fins may also be placed on the top, front, rear or underside of the tube 31.

According to various embodiments, the filter 44 is planar and is disposed in the duct 41 at a position inclined toward an opening provided in an upper portion of the duct 41 like the filter 34 in the duct 31, or is disposed in a space formed between an outer surface and an inner surface of the duct 31. The filter 44 may also be in the form of a filter 14 coupled to a conduit for discharging debris to a reservoir.

According to another embodiment shown in fig. 7, the duct 31', in particular the upper outer surface of the duct, is configured so as to house a set of bars 37 and reservoirs 21", 22". Thus, the upper outer surface of the pipe may for example be raised to accommodate this. In this case, the opening 26 is unnecessary and may be omitted.

Fig. 8, 9A and 9B depict a filtering apparatus 40 according to another embodiment. The filter device 40 differs from the filter device of fig. 2 in that the filter device 40 comprises a duct 41 of rectangular cross-section, the duct 41 having an inlet opening 42 and an outlet opening 43 of rectangular shape. Filter 14 is replaced by filter 44. The filter 44 may be associated with a cleaning device 45, the cleaning device 45 being in the form of a roller brush that moves between a lower portion and an upper portion of the filter 44.

The filtering device 40 may further comprise a set of parallel bars 47, the set of parallel bars 47 being fixed to the outside of the duct 41 facing the inlet opening 42. The rod 47 acts as a breakwater and is able to remove large debris into a reservoir 48 positioned above the pipe 41. For this purpose, each bar 47 has a portion inclined in front of the opening 42 of the duct 41, so that the upper portion of the bar is closer to the downstream of the duct 41 than the lower portion of the inclined portion of the bar. Thus, debris captured by the rod 47 may be diverted upward into the reservoir 48 by the fluid flow. The lower part of the inclined portion of the lever is connected to the lower part of the edge of the opening 42 by a portion facing downstream and slightly inclined with respect to the horizontal position.

According to one embodiment, the grille 47 is also associated with a cleaning device 46, the cleaning device 46 moving along the rod to drive debris captured by the grille towards the reservoir 48.

According to one embodiment, the stem 47 has a hydrodynamic profile against the direction of the fluid flow 2.

According to one embodiment, the tubes 41 are associated with lateral fins 49 arranged as shown in fig. 8 and 9B to keep the tubes 41 just below the surface 1 immersed in the fluid.

According to various embodiments, the filter 44 is planar and is arranged in the duct 41 in a position inclined toward the opening formed in the upper portion of the duct 41 like the grill 17 in the duct 11. The filter 44 may also be in the form of a filter 14 coupled to a conduit for discharging debris to a reservoir.

According to one embodiment, the filter 44 and the rod are substantially parallel and inclined with respect to the longitudinal direction X of the duct, and the duct is configured such that the plane of the inlet opening 42 is parallel to the filter. Thus, if the filter and rod are inclined upwardly, the lower portion of the duct extends further in the upstream direction than the upper portion of the duct.

Fig. 10 depicts a filter 44' according to another embodiment. The filter 44' has a plurality of juxtaposed grooves of V-shaped cross-section. The filter 44' may be arranged in the duct 41 such that its grooves are oriented in the vertical longitudinal plane of the duct and inclined at the top towards the rear of the duct 44. The filter 44' may be associated with a horizontally disposed cleaning brush having a shape that conforms to the cross-sectional shape of the filter in the horizontal plane. The filter 44 'may be cleaned by moving the cleaning brush between the lower and upper portions of the filter 44'.

According to other embodiments, the filter has a square or rectangular cross-section pyramid shape with sharp or rectilinear edge vertices. Thus, to adapt the filter to the filtering device 40, the filter may be pyramid-shaped with a rectangular cross-section and vertices in the form of straight segments.

According to one embodiment, the filter is cleaned by a suction system coupled to a reservoir (e.g., reservoir 21, 21' or 48) that includes a pump connected to a hose whose end moves along the surface of the filter. The reservoir for collecting debris may also be connected to a larger capacity reservoir by plumbing.

According to one embodiment, the filter does not have a grid, but rather consists of parallel bars, for example of vertically arranged parallel bars. It has been found that such filters are easier to clean and create less resistance. The profile of the rods or mesh forming the filter may be such that filter drag is reduced.

Fig. 11A and 11B depict a filtration device according to another embodiment. The filtering device comprises the conduit 41 described with reference to fig. 8, 9A and 9B, and a set of parallel rods 47', these rods 47' being held in front of the upstream opening of the conduit 41 by two floats 9, the conduit 41 being anchored to the floats 9, for example by means of a cable 8. The rod 47 'is able to remove large debris into a reservoir 48' secured above the float 9. For this purpose, the stem 47' is inclined in front of the opening 42 of the duct 41, so that the upper part of the stem is closer to the downstream of the duct 41 than the lower part of the stem. Thus, the debris captured by the rod 47 'may be diverted upwardly into the reservoir 48' by the fluid flow 2.

According to one embodiment, the rod 47 'is associated with a cleaning device that moves along the rod to expel debris toward the reservoir 48'.

The rods 47' may have a hydrodynamic profile so as to minimize their drag. Furthermore, the rod 47' may be hollow so as to have buoyancy, thereby minimizing the volume of the float 9 and thus the resistance of the float 9.

According to one embodiment, the filter present in the above embodiments may be flexible and may roll around rollers at the top and bottom of the pipes 11, 31, 41. The fixed rotating brush can clean the filter wound on one of the rollers when the filter moves upward or downward.

The filter may also be cleaned using a transfer pump that injects a water jet in a direction opposite to the direction of the fluid flow 2.

According to one embodiment, the float 9 is replaced by one or more fins connected to the grille formed by the rods 47' so as to generate lift and to maintain the grille at the desired height, with a portion immersed and a portion exposed.

Fig. 12-16 depict various contours of a duct of a filtering device according to various embodiments. Fig. 12 depicts a filtration apparatus 50 comprising a conduit 51 and a filter 54. The duct 51 includes an upstream section 51a and a downstream section 51b, the length of the downstream section 51b being 7 to 9 times the length of the upstream section 51 a. The internal volume of the upstream section 51a has a trapezoidal cross-section in the horizontal longitudinal plane, which is symmetrical about the longitudinal axis X of the duct 50 and widens in the downstream direction at an angle α1 up to the filter 54. The internal volume of the downstream section 51b has a trapezoidal cross-section in the horizontal longitudinal plane, which is symmetrical about the longitudinal axis X and widens in the upstream direction at an angle α2 relative to the longitudinal axis X up to the filter 54. Externally, the longitudinal section of the upstream section 51a has a rounded shape that widens up to the location of the filter 54. The outer shape of the longitudinal cross section of the downstream section 51b is substantially straight or slightly curved outwardly. The surface area of the outlet opening 53 is smaller than the surface area of the inlet opening 52 and the surface area of the inlet opening 52 is smaller than the positive cross-sectional area of the duct 50 at the location of the filter 54.

Fig. 13 depicts a filtration apparatus 60 comprising a conduit 61 and a filter 64. According to one embodiment, the conduit 61 comprises only the downstream section 61b. The internal volume of the downstream section 61b has a trapezoidal cross-section in the horizontal longitudinal plane, which is symmetrical about the longitudinal axis X and widens in the upstream direction at an angle α2 relative to the longitudinal axis X up to the filter 64. The outer shape of the longitudinal section of the downstream section 61b widens following a curved profile and then becomes substantially rectilinear again. The surface area of the outlet opening 63 is smaller than the surface area of the inlet opening 62 corresponding to the size of the filter 64. The inlet opening 62 may have the described protrusions.

Fig. 14 depicts a filtration apparatus 70 comprising a conduit 71 and a filter 74. The conduit 71 comprises an upstream section 71a and a downstream section 71b, the downstream section 71b having a length equal to the length of the upstream section 71 a. The internal volume of the upstream section 71a has a trapezoidal cross-section in the horizontal longitudinal plane, which is symmetrical about the longitudinal axis X of the tube 70 and widens in the downstream direction at an angle α1 up to the filter 74. The internal volume of the downstream section 71b has a trapezoidal cross-section in the horizontal longitudinal plane, which is symmetrical about the longitudinal axis X and widens in the upstream direction at an angle α2 relative to the longitudinal axis X up to the filter 74. Externally, the longitudinal section of the upstream section 71a has a convex shape that tapers at the inlet opening 72 and the filter 74 and is thicker near the middle of the upstream section. The outer shape of the longitudinal section of the downstream section 71b is substantially linear, and the thickness thereof may be substantially constant.

The surface area of the outlet opening 73 is smaller than the surface area of the inlet opening 72, and the surface area of the inlet opening 72 is smaller than the positive cross-sectional area of the duct 71 at the location of the filter 74.

According to an exemplary embodiment, the angle α1 is 0 ° to 20 °, and the angle α2 is 7 ° to 20 °. In the example of fig. 14, the angles α1 and α2 are 4 ° to 9 °, for example, equal to 6 °.

Fig. 15 depicts a filtration apparatus 80 comprising a conduit 81 and a filter 84. The duct 81 includes only the upstream section 81a. The internal volume of the upstream section 81a has a trapezoidal cross section in the horizontal longitudinal plane, which is symmetrical about the longitudinal axis X and widens in the downstream direction at an angle α1 up to the filter 84. Externally, the longitudinal section of the upstream section 81a has a rounded shape that tapers at the inlet opening 82 and the outlet opening 83 and is thicker between the openings 82, 83. The surface area of the outlet opening 83 corresponding to the size of the filter 84 is larger than the surface area of the inlet opening 82.

Fig. 16 depicts a filtration apparatus 90 comprising a conduit 91 and a filter 94. The conduit 91 differs from the conduit 71 in that the surface area of the outlet opening 93 thereof is larger than the surface area of the inlet opening 92.

In order to evaluate the effectiveness of the above-described filtering apparatus comprising a filter arranged in a pipe, it is necessary to consider the resistance of the filtering apparatus when it is driven through the water, for example by a ship. The resistance is the result of four components added to each other, namely the pressure resistance and the viscous resistance of the filter, and the pressure resistance and the viscous resistance of the pipe. Typically, resistance is related to the velocity of the fluid along the pipe wall and through the filter. The pressure resistance of the filter is related to the shape of the filter, the combined surface area of the mesh of the filter, and the cross-sectional area of the filter. The viscous drag of the filter is caused by friction of the water against the walls formed by the mesh of the filter. The viscous drag of the filter is low because of the small friction area. The viscous drag of a pipe depends on the area of friction of the fluid on the inner and outer walls of the pipe. The pressure resistance depends on the shape and cross-sectional area of the conduit.

To evaluate the performance of the various profiles shown with reference to fig. 1 and 12-16, various simulations were performed, fixing the fluid velocity around the pipe at 11m/s, i.e. 21.38 knots, and setting the cumulative surface area of the mesh of the filter to 50% of the total surface area of the filter, these areas being the areas in the transverse plane. The results of the arrangement in table 1 below were obtained with the planar filter placed in a circular cross-section duct in an inclined position with the upstream surface of the filter facing upwards. The results collated in Table 2 below are obtained with the planar filter placed perpendicular to the longitudinal axis X of the tube.

TABLE 1

TABLE 2

The first column of tables 1 and 2 contains the numbers of the filter devices used in fig. 1 and 12 to 16. Columns 2 and 3 of tables 1 and 2 collate the values of the pressure resistance and the viscous resistance of the filters. Columns 4 and 5 of tables 1 and 2 collate the values of the pressure resistance and the viscous resistance of the pipes. Column 6 contains the sum of the resistance values indicated in columns 2 to 5. It should be noted that the negative resistance value corresponds to the force that contributes to the forward movement of the device through the fluid and is obtained thanks to the projections formed by the outer surface of the upstream section of the duct. Column 7 collates the values of the fluid flow rate at the outlet of the pipe. Finally, the last column indicates the value of the ratio of flow rate to total resistance, enabling the effectiveness of the various profiles to be compared.

As is evident from tables 1 and 2, the inclined position of the filters is generally more advantageous and the profile of the filter devices 10, 50 and 60 performs better than the profile of the filter devices 70, 80 and 90. It should also be noted that the profile of the filtering device 80, which is intended to limit the fluid pressure at the filter, performs the worst. Furthermore, if the performance of the profiles of the filter devices 70 and 90 are compared, providing the outlet opening with a smaller surface area than the inlet opening makes it possible to improve the performance of the profiles.

Those skilled in the art will clearly appreciate that the present invention is applicable to a variety of embodiment variations and a variety of applications. In particular, the invention is not limited to devices towed or propelled by a vessel. In particular, the apparatus may be fixed relative to a structure in which the fluid flow is piped, for example to a stationary structure which holds the apparatus in the waterway.

Furthermore, the internal cross-section of the conduit may be of any shape, such as circular, oval, square, rectangular, trapezoidal, triangular, polygonal, or a combination of these shapes.

Furthermore, the filter may have a different size mesh, for example a thicker mesh, to allow plankton to pass through. The filter does not necessarily cover the entire cross-sectional area of the conduit. Furthermore, a plurality of filters may be arranged in series in the duct and spaced apart along the longitudinal axis X.

Claims (14)

1. A filtration apparatus comprising a pipe (11, 31, 41, 51, 61, 71) intended to be immersed in a fluid flow, and a filter (14, 34, 44, 44',54, 64, 74) arranged in the pipe to filter the fluid entering the pipe, the pipe comprising:

an inlet opening (12, 32, 42, 52, 62, 72) receiving the fluid flow,

an upstream section (11 a,31a,41a,51a,71 a) extending from the inlet opening and accommodating the filter,

outlet openings (13, 33, 43, 53, 63, 73), and

a downstream section (11 b,31b,41b,51b,61b,71 b) extending from the filter up to the outlet opening to convey the fluid flow exiting the filter towards the outlet opening, the length of the downstream section being greater than or equal to the length of the upstream section, the surface area of the outlet opening being smaller than the surface area of the inlet opening, these surface areas being in a plane perpendicular to the longitudinal axis (X) of the conduit.

2. The apparatus according to claim 1, wherein the upstream section (11 a,31a,41a,51a,71 a) has an internal profile in a plane passing through the longitudinal axis (X) of the duct, the internal profile being oriented towards the longitudinal axis of the duct at an angle of zero or 0 ° to 16 ° to the direction of fluid flow.

3. The apparatus according to any one of claims 1 and 2, wherein the duct (11, 31, 41, 51) has a protrusion on its outer surface surrounding the inlet opening (12, 32, 42, 52), the protrusion having a tangent (T1) at the inlet opening, the tangent (T1) being at an angle of more than 45 ° with respect to a longitudinal axis (X) of the duct (11, 31, 41, 51).

4. A device according to any one of claims 1 to 3, wherein the downstream section (11 b,31b,41b,51b,61b,71 b) has a straight or curved internal profile in a plane passing through the longitudinal axis (X) of the duct, which internal profile is at an angle of 0 ° to 20 °, preferably 4 ° to 9 °, to the direction of the fluid flow.

5. The apparatus according to any one of claims 1 to 4, wherein the surface area of the outlet opening (13, 33, 43, 53, 63, 73) is tailored such that the velocity of the fluid flow at the outlet of the duct is 80 to 110% of the velocity of the fluid around the outlet opening.

6. The apparatus of claim 5, wherein the outlet opening (13, 33, 43, 53, 63, 73) has a surface area of 0.1 to 5 times the total fluid passing surface area through the filter (14, 34, 44, 44',54, 64, 74).

7. The apparatus according to any one of claims 1 to 6, wherein the cross-section of the conduit (11, 31, 41, 51, 61, 71) is circular, oval, trapezoidal, triangular, polygonal, square or rectangular in shape, or a shape consisting of these shapes.

8. The device according to any one of claims 1 to 7, comprising a grille (23, 17, 47), said grille (23, 17, 47) being positioned in front of said filter (14, 34, 44, 44',54, 64, 74) and having a fluid flow through surface area greater than that of said filter, said grille being positioned in said duct, or in front of an opening of said duct, so as to act as a filter and/or breakwater, said grille being potentially associated with a cleaning or suction device (16, 36, 46) for removing debris trapped by said grille.

9. The apparatus of any one of claims 1 to 8, comprising at least one filter having one of the following features:

-said filter (14) has a conical or pyramidal shape;

the filter (14) has a conical or pyramidal shape with a debris discharge opening (24) at the apex of the conical or pyramidal shape;

the filter (34) is planar and arranged perpendicular to the longitudinal axis (X) of the duct (31);

the filter (34) is planar and is arranged obliquely with respect to the longitudinal axis of the duct;

the filter (44') has a plurality of juxtaposed grooves having a V-shaped cross-section;

each face of the filter has a convex portion and a concave portion;

the filter consists of parallel rods; and

the filter includes rods or mesh whose profile is such that the resistance of the filter is reduced.

10. The device according to any one of claims 1 to 9, wherein the filter (14, 34, 44, 44') is associated with a cleaning device (15, 35) or a suction device to remove debris captured by the filter.

11. The apparatus of any one of claims 1 to 10, comprising means (19, 39, 49) configured to push the apparatus upwards when the apparatus is fully immersed in water, and means configured to push the apparatus downwards when the apparatus is not fully immersed in water.

12. A method for collecting solid debris near a surface of a body of water, the method comprising the steps of:

providing a filter device according to any one of claims 1 to 11, and

associating the filtering device with a structure for maintaining the pipes (11, 31, 41, 51) of the filtering device immersed in a water flow at the surface of the body of water, or

-associating the filtering device with a vessel to keep the pipe (11, 31, 41, 51) of the filtering device immersed at the surface of the body of water, and-moving the vessel at cruising speed to create a flow of water within and around the pipe of the filtering device.

13. The method of claim 12, comprising the steps of: the debris is collected in a reservoir (21, 22, 21',22',21",22",48, 48 ').

14. The method of claim 12 or 13, wherein the water flow has a velocity of 1m/s to 15m/s.