Terminal dam apparatus
The present invention relates to a terminal dam apparatus for use in collecting oil or the like floating on a water surface, comprising a barrier member having an opening for the through-flow of collected oil, and having end portions which, in use, e. g. are connected to the ends of respective dam lengths for the formation of a horseshoe_. configuration for the guiding of captured oil towards the apparatus.
From GB patent No. 1 519 693 there is known an apparatus for collecting and recovering oil and the like floating on a water surface, and showing essentially the above-mentioned features. In this known apparatus it is the question of a concentrator comprising a flexible duct formed in such a manner that the inlet of the duct has a larger dimension extending parallel to the water surface and a smaller dimension perpendicular thereto, and such that the outlet has a smaller dimension extending parallel to the water surface and a larger dimension perpendicular thereto. Thereby it is achieved that the layer of oil or the like becomes deeper during its passage of the concen¬ trator duct. This apparatus needs additional facilities to take up the oil or the like which is collected, and further it will not be very suitable for use at sea in rough sea.
The object of-the present invention is to provide a dam apparatus which in particular will contribute to increasing the efficiency of the oil defence in that it will provide an effective oil collection also under very adverse weather conditions and will function as a release valve when it is used together with conventional dams deployed in a horseshoe configuration.
Simultaneously, it is an object to provide a dam apparatus which is easy to operate, simple to assemble and easy to clean, at the same time as it is sturdy and durable and also adapted to the vessels presently used in the oil defence, such as supply ships and purse-net boats.
For the achievement of the above-mentioned objects there is provided a terminal dam apparatus of the introduc- torily stated type which, according to the invention, is characterized in that the barrier member is a rigid plate structure which, by means of buoyancy means, are arranged to float in an essentially vertical position, and on which there is mounted a gate means and an associated operating means which may be actuated to move the gate between posi¬ tions wherein the opening is closed and open, respectively, and that a flexible hose is connected to the opening on the side facing away from the collecting area, for conduc¬ ting away collected oil to a vessel or the like.
The invention will be more closely described below in connection with an exemplary embodiment which is schema¬ tically shown in the drawings, wherein:
Fig. 1 shows a front elevation of the terminal dam apparatus;
Fig. 2 shows a side view of the terminal dam apparat in section along the line II - II in Fig. 1;
Figs. 3A and 3B show an upper frame forming part of the terminal dam, viewed from the side in Fig. 3A and from above in Fig. 3B;
Fig. 4 shows a simplified front view of the terminal dam, including parts of the operating system of the dam gate omitted in Fig. 1; and
Fig. 5 shows a front view corresponding to Fig. 4, but with the gate means shown in open position, and wherein there are also shown further details of the operating and remote control system of the terminal dam not shown in Fig. 4.
Such as appears from Figs. 1 and 2, the shown terminal dam apparatus comprises a barrier member in the form of a rigid and, in the illustrated embodiment, rectangu lar and plannar plate structure having a plate 1 which in its central area has an opening 2 which is oval in the illustrated embodiment. The dam wall constituting plate 1 may consist of acid-resisting light metal or possibly of a suitable plastic material, and to the rear side of the plate there are attached a plurality of horizontally
extending braces in the form of square bars 3. In Fig. 2 nine such bars (not shown in Fig. 1) are suggested.
To the upper edge of the dam plate 1 and at right angles thereto there is attached an upper supporting plate 4 carrying a horizontal upper frame or top frame 5 the structure of which appears from Figs. 3A - 3B. The top frame consists of a tube structure of transversely extendi rods 6 and longitudinally extending rods 7. The transvers extending rods 6 project equal distances outwards on each side of the supporting plate 4 and are by means of clamps 8 attached thereto with suitable bolts 9 or the like. The longitudinally extending rods 7 are welded to the transvers extending rods 6 and in the illustrated embodiment consist of three rods on each side of the supporting plate 4. on the other side of the supporting plate 4 there is arranged a longitudinally extending buoyancy body 10 which, in use, has a wave-breaking function and which also is filled with pressurized air to provide an air source for the pneumatic control system of the dam apparatus, such as more closely described below. The body 10 is attached to the supporting plate 4 by means of suitable clamps 11.
Such as appears from Figs. 1 and 2, a number of side floats 12 are attached to the underside of the top frame 5 on each side of the dam plate 1. These floats determine the floating level of the apparatus (the water line 13 is suggested in Fig. 2) and constitute dam-stabiliz pontoons. In the illustrated embodiment three floats 12 are arranged on each side, and each of these floats is attached to the top frame 5 by means of cushioning means shown in the form of a number of shock absorbers 14. Thus, the floats are independent of each other in order to be able to absorb wave motions individually, so that the position of the terminal dam in rough sea is stabilized.
For additional stabilization of the floating position of the terminal dam, a plurality of stabilizing weights 15 are attached along the lower edge of the dam plate 1.
For reinforcing the dam structure, bracing means
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are mounted on each side of the dam plate 1, and in the illustrated embodiment at each end of the dam apparatus. Each bracing means consists of an oblique rod 16 which is attached, e. g. by welding, with its lower end to the dam plate 1 and with its upper end is attached to the outer edge of the top frame 5, and further of a horizontal brace 17 which is attached with one end to the dam plate 1 and with its other end is attached to the rod 16.
At each end of the dam plate 1 there are mounted fastening means 18 for connection of e. g. the topical types of conventional dams which may be thought to be used together with the terminal dam apparatus in use at sea.
In order to make the terminal dam apparatus readily visible in operation, it is provided with a number of safety markers 19. These consist of orange-coloured, self-lighting pennants and are attached e. g. one in each corner of the top frame 5 and at each end of the wave- breaking buoyancy body 10.
The oval opening 2 in the dam plate 1 is surrounded by a flange 20 attached to the dam plate 1 and projecting somewhat outwards on each side thereof, as shown in Fig. 2. A flexible hose 21 is inserted with one end thereof on the flange 20 on the side of the dam apparatus facing away 'from the oil collecting side, and is attached to the flange by a suitable clamping means 22. The hose extends between the dam opening 2 and a suitable recovery means for collected oil, e. g. a tank on a vessel (not shown) . The hose 21 is kept floating on the surface of the water by means of floating bodies (not shown) , e. g. in the form of pneumatic tires surrounding the hose. In the section of the hose extending between the opening 2 and the surface of the water, the hose has a decreasing cross-section and is e. g. conically tapering, in order to obtain a pressure on the oil flowing into the hose during operation, so that the oil can be transferred to the recovery means without the use of special pumping means. In Fig. 2 the oil flow is suggested with arrows A.
On the opposite side of the dam plate in relation
to the hose 21 there is mounted a gate means with an associated operating means for movement of the gate between positions wherein the opening 2 is closed and open, respec¬ tively. In the illustrated embodiment the gate means consists of a pair of §3_*escsτfc-shaped shutters 23 and 24, respectively, which are slidably mounted on the dam plate 1 and by means of the operating means can be moved towards each other to mutually sealing connection for closing of the opening 2, as shown in Figs. 1 and 4, or away from each other for partial or full opening of the opening, as shown in Fig. 5. The sealing connection in closed position is achieved by a partial overlapping of the shutters. To each of the shutters there are attached a number of horizon¬ tally extending braces 25. Three such braces are shown in Figs. 1 and 2 (omitted in Figs. 4 and 5).
In the closed position of the shutters. 23 and 24 these are sealingly bearing against the associated end of the* flange 20 through an encircling gasket 26 which may e. g be made of polyethylene. When the shutters are in motion, these are in sliding contact with horizontally extending slide bars 27 attached to the dam plate 1. In the illustrat embodiment, three such slide bars in the form of slide rods with circular cross-section are provided for each of the shutters. Instead of the illustrated slide bars other forms of bearing means may be used, e. g. mutually engaging guide members which are attached to the dam plate and the shutter in question, respectively.
For stable movement of the shutters 23 and 24, each of the shutters are slidably mounted, by means of an upper holder 28 and a lower holder 29, on a horizontal, upper slide or guide rod 30 and a horizontal, lower slide or guide rod 31, respectively. Like the shutters, the holders may be made of acid-resisting light metal or plastic, and consist of a bearing member and a blade member projecting therefrom and being attached to the shutters by means of suitable bolts. The guide rods 30 and 31 are attached to the dam plate 1 by means of end mountings 32. For stopping the shutters 23, 24 in the proper closing position when they are moved towards each other, stoppers 33 are provided ,¥.Pi
on the guide rods and constitute abutments against the holders in the closing position of the shutters. The stoppers may be attached on the quide rods, or they may be fastened to the dam plate 1 such as shown in Fig. 2. The operating means for movement of the shutters
23 and 24 in the illustrated embodiment consists of double- acting, hydraulic cylinders 34 of which one cylinder pair is provided for each shutter. Each cylinder is at one end thereof attached to the dam plate 1 by means of a cylinder mounting 35, whereas the piston rod end of the cylinder is attached to the shutter in question by means of a rod mounting 36. The hydraulic cylinders are operated by means of oil which is supplied by way of containers 37 for hydraulic oil, one container for each cylinder pair (schematically shown in Fig. 4) . Even if the cylinder/ piston units could be operated pneumatically, it is advan¬ tageous to use oil as working medium under the surface of the sea, in order to avoid condensation in the cylinder/ piston units. Such as mentioned above, the control system for actuating the cylinders is, however, pneumatic, and for each cylinder it is thus provided a pneumatic/hydraulic control valve 38 which, by way of an associated air hose 39, communicates with a respective air bleed 40 in the buoyancy body 10 constituting the pressurized air source of the control system. The buoyancy body 10 is provided with vacuum valves 41 opening automatically when the pressure in the buoyancy body decreases below a certain limit, so that the correct pressure is achieved again.
The control system is arranged to be actuated or operated by means of a radio remote control system of commercially available type, and for this purpose a re¬ ceiver 42 (Fig. 5) is placed on the terminal dam apparatus, which receiver can receive control signals from a trans¬ mitter unit (not shown) by way of an antenna 43 projecting upwards from the buoyancy body 10 and being provided with a marker flag 44. The receiver 42 is connected to a directional valve 45 which is in turn connected to the pneumatic/hydraulic control valves 38, so that the latter
are positioned in the correct position for operation of the hydraulic cylinders for opening and closing of the ga means in dependence of the signals received by the recei 42. The various connections between the directional val 5 45 and the pneumatic/hydraulic valves 38 are not depicte in the Figures, and the hydraulic connections between the hydraulic aggregates 37, the valves 38 and the hydraulic couplings (not shown) of the cylinders 34 are also omitte for the sake of the survey, as the arrangement is suppose 10 to be obvious to a person skilled in the art.
Such as appears from Fig. 5, the terminal dam apparatus is also provided with a green and a red lamp 46 and 47, respectively, which are actuated synchronously with the opening and closing of the gate means. Thus, th 15 green lamp 46 is illuminated when the shutters 23, 24 are moved to the closed* position, and is kept illuminated as long as the opening 2 is closed, whereas the red lamp 47 is illuminated when the shutters are moved towards and ar in the open position. 20 In addition to the fact that the gate means can b opened and closed by remote control via radio, the operat may also take place in dependence of the actual level of the collected oil. For this purpose one shutter 24 is provided with a plurality of sensors 48 arranged above ιy r each other in the vertical overlapping area. Advantageo these sensors may be coupled to the directional valve 45 in order to open the shutters at a certain oil level.
On the dams coupled to the terminal dam apparatus there may be mounted tension sensors sensing the mechanic 0 stress and providing for opening of the shutters when a certain limit is exceeded, so that the terminal dam appar then automatically functions as a release valve for the dam system of which the terminal dam apparatus forms part.
Further, at the bottom of the terminal dam there 5 may be provided a shield (not shown) to guide the oil int the through-flow opening. This may be necessary if the sea is rough. Further, it may be contemplated to be
arranged an additional shutter which, by means of oil level sensors, can be arranged to shut the lower part of the through-flow opening 2 in dependence of the actual level of collected oil, so that it is secured that it is essential only oil which flows through the opening.
When using the terminal dam apparatus, this is deployed together with conventional dams as menioned above, so that a horseshoe configuration is formed with the termina dam disposed in the bottom of the horseshoe, and so that win waves and water currents will move the oil forwards to the terminal dam. The dam system,may be deployed and hauled by a pair of vessels, or it may also be stationary. Under calm weather conditions the oil can be collected in that the two vessels move towards the oil discharge. When using the present terminal dam apparatus, the critical load on a dam system which is deployed in a horseshoe configuration, will be reduced with 60 - 68% according to effected tests. One achieves an effective collecting of oil in addition to the fact that the terminal dam can function as a release valve if the the weather conditions should make this necessary. Thus, onecan avoid failure in the dam system as a result of excessive load. By use of the remote control system as described above, a simple operation is achieved as all manoeuvering can take place by means of a pair of levers in connection with the transmitter. Such a remote control system can e. g. have a range of approximately 1000 meters.
The apparatus according to the invention has above been described in connection with the application at sea where it is intended to be connected to conventional dams for the formation of a e. g. horseshoe-shaped dam system. However, the terminal dam apparatus can also be contemplated to be used in rivers, in order to capture and transfer toxic chemicals or other dangerous substances which have been dis- charaged and flow in the upper layers of the river water. The apparatus is then installed with open gate and so that th contamination in the upper layers of the river water is guided towards the opening and flows therethrough. The dis¬ charge is then conveyed through the flexible hose to a^gyR^
collection means, e. g. a tank, from which it may possibly be carried away and distroyed.