INSTALLATION FOR MULTIPLE SKIMMING

Abstract

Apparatus (10) for removing gases in a liquid, and/or for removing foam and particles from a liquid and/or for the transport of liquid, the device (10) comprises conduits (16) for transporting the liquid from a first location to a second location, where the conduit (16) comprises a first upstream conduit portion (16a) for receiving of liquid, a substantially horizontal conduit portion (16b), a downstream conduit portion (16c) to discharge liquid out of the conduit (16), and a venting conduit portion (16d) to discharge gases, particles and a part of liquid out of the conduit (16) via conduit portion (16e) and means (17) arranged in the upstream conduit portion (16a) and/or horizontal conduit portion (16b) for supplying microbubbles to the conduit (16), and that in the conduit (16) means (19) are provided for establishing vacuum in parts of the conduit (16), characterized in that the device (10) in the conduit portion (16b) comprises two or more venting conduit portions (16d).

Claims

1-41. (canceled)

42. A device (10) for removal of gases in a liquid, and/or for removal of foam and particles from the liquid and/or for transport of the liquid, the device (10) comprising: a pipeline (16) to transport the liquid from a first location to a second location, where the pipeline (16) comprises: a first upstream pipe section (16a) for intake of liquid; a principally horizontal pipe section (16b); a downstream pipe section (16c) for passing liquid out of the pipeline (16); and a venting pipe section (16d) to lead gases, particles, and a portion of the liquid out of the pipeline (16) via a further pipe section (16e); wherein one or more injector/ejector means (17) is arranged in the upstream pipe section (16a) and/or the horizontal pipe section (lob) for supplying microbubbles to the pipeline (16); wherein means (19) are arranged in the pipeline (16) to establish negative pressure in sections of the pipeline (16); and wherein the device (10) in the pipe section (16b) includes two or more venting pipe sections (16d).

43. The device (10) according to claim 42, wherein the two or more venting pipe sections (16d) are arranged in connection with the horizontal pipe section (16b) or in the transition between the horizontal pipe section (16a) and the downstream pipe section (16c), and wherein the device is comprised of 3 or more of the venting pipe sections (16d).

44. The device (10) according to claim 42, wherein adjacent to each venting pipe section (16d, 16d′, 16d″, 16d′″) the further pipe section (16e, 16e′, 16e″, 16′″) is arranged for the removal of gases, particles and the part of liquid separated from the venting pipe sections (16d, 16d′, 16d″, 16d′″).

45. The device according to claim 42, wherein the one or more injector/ejector means (17) is provided in the pipeline (16) for the supply gases to the pipeline (16), wherein the one or more injector/ejector means (17) is arranged in a horizontal pipe section (16b), or wherein the one or more injector/ejector means (17) is arranged just downstream of one or more of said venting pipe sections (16d, 16d\ 16d″, 16d′″), or wherein the one or more injector/ejector means (17) is arranged in the upstream pipe section (16a).

46. The device according to claim 42, wherein in connection to each venting pipe section (16d, 16d′, 16d″, 16d′″) a number of pipe sections (16e, 16e′,16e″, 16e′″) are arranged for the discharge of the gases, particles, and liquid which are separated in the venting pipe sections (16d, 16d′, 16d″, 16d′″).

47. The device according to claim 42, wherein each of the one or more injectors/ejectors (17) is connected to a pump for the supply of water under pressure to the one or more injectors/ejectors (17).

48. The device according to claim 42, wherein the one or more injectors/ejectors connected to an open-air hose which brings air to the one or more injectors/ejectors (17).

49. The device according to claim 42, wherein the gases, particles and liquid are passed from the venting pipe sections (16d, 16d′, 16d″, 16d′″) to a cyclone (20) for the separation of the gases from the liquid.

50. The device according to claim 49, wherein to the upper part of the cyclone (20) means (19) are arranged for establishing an underpressure in the cyclone (20) and the venting pipe sections (16d, 16d′, 16d″, 16d′″).

51. The device according to claim 42, wherein 0-25% of the liquid which is passed through the pipeline (16) are brought via the venting pipe section (16e).

52. The device according to claim 51, wherein 0.01-10% of the liquid which is passed through the pipeline (16) are brought via the venting pipe section (16e).

53. The device (10) according to claim 42, further comprising a pumping device (18) for pumping the liquid in via the upstream pipe section (16a) or the horizontal pipe section (16b).

54. The device according to claim 42, wherein the upstream pipe section (16a) and/or the horizontal pipe section (lob) comprise a garland (21) with openings (21a), adapted for passively sucking air into the liquid stream which is passing through the horizontal pipe section (16b).

55. The device according to claim 42, wherein an addition of air is arranged in the venting pipe section (16d) to give an extra lift to the foam.

56. The device according to claim 42, wherein the venting pipe sections (16d, 16d′, 16d″, 16d′″) have a certain volume which ensures a large interfacial area liquid: gas, and that the liquid circulates slowly through the pipeline (16) so as to reduce the amount of gas flowing with the liquid via the downstream pipe section (16c) to the second liquid volume.

57. The device (10) according to claim 42, wherein the device (10) is arranged in an installation for breeding marine organisms.

58. The device (10) according to claim 42, wherein the device (10) is arranged in an installation for the treatment of wastewater.

59. The device (10) according to claim 42, wherein in the pipeline there are means for the supply of oxygen, so that oxygen is supplied to the liquid before discharge via the downstream pipe section (16c).

60. The device (10) according to claim 50, wherein the underpressure in the pipeline (16) and the cyclone (20) is sufficient to carry foam and smaller particles with the gas-liquid flow out of the pipeline (16).

61. The device according to claim 42, wherein the liquid level in a liquid volume A and a liquid volume B is different, so that the water through flow in the pipeline (16) is wholly or partially driven by the level difference.

Description

DESCRIPTION OF FIGURES

[0051] Preferred embodiments of the invention shall, in the following, be described in more detail with reference to the accompanying figures, in which:

[0052] FIG. 1 shows schematically a device for the removal of gases and particles from a liquid which is passed through a pipeline.

[0053] FIG. 2 shows schematically a device for the removal of gases from a liquid, by gases, particles and liquid being further separated into a cyclone.

[0054] FIG. 2 shows an embodiment of the present invention in which a number of cleaning steps are carried out.

[0055] FIG. 3 shows an embodiment in which the horizontal pipe section is provided with several sections for the extraction of gases (and smaller sections of liquid).

[0056] FIG. 4 shows an embodiment in which the horizontal pipe section is provided with venting sections having a longitudinal direction. In the embodiment shown, there are two such longitudinal venting sections.

[0057] FIG. 5 shows in cross section a configuration of the pipeline 16b with a rectangular cross section.

DETAILED DESCRIPTION OF THE INVENTION

[0058] FIG. 1 shows the principle for the cleaning of a liquid as it is passed through pipelines 16. The liquid can be moved from a first liquid volume A to a second liquid volume B as indicated in FIG. 1, but the liquid can also be moved from one point in liquid volume A to another point in liquid volume A, i.e. from a location in liquid volume A to another location in the same vessel. Often, it is appropriate to move a fluid from the centre of a container to a point closer to the container periphery.

[0059] As shown in FIG. 1, arranged in a first liquid volume A are one or more pipelines 16 for the circulation of water from a first liquid volume A to a second liquid volume B. There may, of course, be several such pipelines 16 for the circulation of water from a first to a second fluid volume B. The pipelines 16 have an upstream pipe section 16a that extends from the first liquid volume A and the, in the main, vertically upward to above the surface level of the first liquid volume A, and this upstream pipe section 16a is used for the intake of liquid to the pipeline 16.

[0060] In a section above the liquid level in liquid volume A, there is an upstream pipe section 16a in fluid communication with a horizontal pipe section 16b. Preferably, this pipe section 16b is arranged gently inclined, or mainly horizontal. Downstream of the horizontal pipe section 16b, the liquid is further transported through a downstream pipe section 16c. This downstream pipe section 16c is arranged, in the main, vertically and carries the liquid out of the pipeline 16 and over to the liquid section B. The horizontal pipe section 16b can, in some preferred embodiments, be of a considerable length so that the liquid is transported a considerable distance. In a section 16d, gases, foam and some liquid are removed from the main fluid stream. This section 16d is preferably connected to pipe section 16b or in the transition between pipe section 16 and pipe section 16c.

[0061] In a section of upstream pipe section 16a, the horizontal pipe section 16b, or the pipe section 16d, an injector 17 is arranged. The injector 17 supplies gas microbubbles, preferably air, to the pipeline 16. The microbubbles which are transported through the pipeline 16 together with the liquid from liquid volume A will cause gases and smaller particles that are dissolved in the liquid volume A to seek the microbubbles. For example, if CO.sub.2 is dissolved in the first volume of liquid A, this will be drawn to the microbubbles and could be vented out of the liquid in the tube section 16d. By the term “injector” is meant any supply of a gas into a liquid stream so that microbubbles of gas or air are formed in the liquid. The term thus also covers an “ejector” which is based on the gas being passively sucked into the liquid jet (venturi) and an “injector” which is based on something being injected (forced) into the liquid/gas stream.

[0062] An underpressure is established in the pipeline 16 in that means 19 to generate an underpressure is in communication with the pipeline 16. The liquid flow that goes through the horizontal pipe section 16b is then separated by the pipe section 16b going over to a downstream pipe section 16c where the majority of the liquid flows through and to a venting section 16e (shown in FIG. 2) where gases are extracted from the pipeline 16 due to the established underpressure and the microbubbles supplied. By adjusting the underpressure in the pipeline 16, and adjusting the dimensions (diameter) of the downstream pipe section 16c and the venting section 16d, it is possible to also transfer a part of the fluid that flows through the horizontal pipe section 16b via the venting section 16e.

[0063] Tests have shown that it is possible to transfer up to 25% of the liquid via the venting section 16e. However, it is preferred that between 0.01 and 10% of the liquid is taken out via the venting part 16e and the remaining liquid is passed through the downstream pipe section 16c.

[0064] The supply of gases, preferably air, will ensure that the liquid which rises in the pipeline in upstream pipe section 16a or horizontal pipe section 16b is lighter and also lighter than the liquid which is discharged from the pipeline via pipe section 16c as gases/air is removed from the liquid in a venting section 16d. In that the liquid in pipe section 16a is lighter than in pipe section 16c the flow and transport of the liquid through the pipeline 16 are established. Experiments have shown that with sufficient supply of air via injector 17 and the establishment of a sufficient underpressure via fan 19, the liquid is transported at a sufficient speed through the device 10, without the need to use pumps to pump the liquid.

[0065] There will also be the lighter part of the liquid (which has a large amount of dissolved gas bubbles) discharged via the venting pipe section 16e.

[0066] In some embodiments of the device 10, in a section of the pipeline 16, i.e. in either the upstream pipe section 16a, horizontal pipe section 16b or downstream pipe section 16c, a pumping device 18 is preferably arranged to pump the water up from the first volume of liquid. Preferably this is a propeller pump 18 which is suitable for pumping large quantities of low-pressure water. For example, as shown in FIG. 1, the pump is arranged in the upstream pipe section 16a such that liquid is drawn from the first volume of liquid via the upstream pipe section 16a.

[0067] In the solution which is shown in FIG. 1 the pipe section 16b has a considerable length, and it is slightly sloped downwards so that liquid which is pumped to the top of the pipe section 16b will flow through the pipe section 16b. A large liquid surface is generated and this provides effective removal of any gases that are in the first volume of liquid A. Thus, the liquid contains a lesser amount of dissolved gases after it has passed through pipe section 16b and the venting section 16d.

[0068] If the device 10 is used in a fish farm, the first volume of liquid A is usually the water reservoir in which the marine organisms, such as fish, live, and this will eventually contain large amounts of dissolved CO.sub.2. It is therefore an aim of the present invention to remove this CO.sub.2 or to simultaneously replace it with oxygen or air. In the first liquid there is a relatively high content of CO.sub.2 and low O.sub.2. Furthermore, there will be a mixture of water and small air bubbles in the pipeline sections 16a and 16b, and CO.sub.2 goes from being dissolved in water and into the air bubbles due to the equilibrium principle. In embodiments of the invention which are not shown in the figures, there will be means in the downstream pipe section 16c for the supply of oxygen to the liquid which flows out of the pipeline 16 via the downstream pipe section 16c.

[0069] As shown in FIG. 1, there is in a section, preferably in the transition between the horizontal pipe section 16b and the downstream pipe section 16c, a device 19 arranged to establish an underpressure in the pipe section 16b. This is shown by a fan 19 in FIG. 1. The air bubbles in the liquid will be with such an underpressure drawn out of the liquid which flows through horizontal pipe section 16b and further via the venting section 16d to the downstream pipe section 16c. Due to the underpressure and large surface area between the air bubbles and water, this method will effectively remove CO.sub.2 and other gases from the liquid.

[0070] As shown in FIG. 1, the liquid in the first volume of liquid can be exchanged for gases as it is passed through the device 10, i.e. through the different pipe sections 16a, 16b and 16c. Along with this exchange of gases, the device 10 can be used to move liquid. As shown in FIG. 1, liquid is transported from the first liquid volume A via the pipeline 16 to a second liquid volume B. This can be from one net cage to another net cage or it can be from one segment of one net cage to another segment of the net cage. In some embodiments, the liquid which is transported through the pipeline 16 is returned to the same volume of fluid from which it is retrieved, i.e., the first and second volumes of liquid are the same net cage or net cage segment (as shown in FIG. 3).

[0071] FIG. 2 illustrates an alternative solution to show the principle of the present invention i.e., there is in addition to the solution in FIG. 1, a cyclone 20 used to separate gases and liquid. It can be seen from FIG. 2 that the device comprises an, in the main, vertical upstream pipe section 16a which passes into an, in the main, horizontal pipe section 16b. In the pipe section 16a means are arranged for the supply of air, preferably microbubbles of air. It is not necessary, but in some embodiments, means 18 (not shown in FIG. 2) in the upstream pipe section 16a are also used to draw water from a first liquid volume A and through the pipeline 16. In the transition between the horizontal pipe section 16b and the downstream pipe section 16c, a venting section 16d is established so that gases, at transport of liquid and air in via the upstream pipe section 16a and horizontal pipe section 16b, in a venting section 16d are removed from the liquid and discharged from the pipeline 16 via venting pipe section 16e. Discharged from the venting section 16d, foam with particles and gases is extracted via the pipe section 16e, with means 19 being provided in the pipe section 16e or in conjunction with the pipe section 16e to establish an underpressure in the venting section 16d. The means 19 for establishing an underpressure can be directly connected to pipe section 16e, and not necessarily via the cyclone 20 as shown in FIG. 2.

[0072] By establishing a sufficient underpressure and appropriate dimensioning of the pipe peripheries for the pipe section 16e and the pipe section 16c, a part of the liquid will also be discharged from the pipeline 16 via the venting pipe section 16e. It is the lightest portion of the liquid, i.e. the one with high content of gas bubbles, which will be discharged through the venting pipe section 16e. The heaviest part of the liquid will be discharged downstream of the pipe section 16c.

[0073] It is an advantage that the venting section 16d is of a certain volume, and in particular that the liquid surface is of a certain size. This results in a large interfacial fluid: gas which, together with the underpressure that is established, will provide effective extraction of gases dissolved in the liquid. The air bubbles which are supplied to the liquid from the injector 17 via the upstream pipe section 16a or the horizontal pipe section 16b will also cause smaller particles to be drawn out of the liquid and into the gas phase, and out of the venting pipe section 16e. Foam will also form in this section which is pulled over into the pipe section 16e. The conditions which are established in the venting section 16d, i.e., underpressure, large surface, and liquid with air bubbles, will effectively separate gases from the liquid. The gases are removed via the pipe section 16e, and the largest part of the fluid is taken out via the downstream pipe section 16c.

[0074] Further, in the device 10 shown in FIG. 2, a garland 21 with openings 21a for passive suction of air is arranged. This garland 21 can be arranged in the upstream pipe section 16a above the liquid surface in the liquid volume A, or it can be arranged in the horizontal pipe section 16b. The openings 21a can be adjustable so that one can control the amount of air supplied.

[0075] Further, in the device 10 shown in FIG. 2, there is an injection device 22 which can supply (inject) liquid to the fluid flow in the pipeline 16. The injection device 22 is preferably arranged in the upstream pipe section 16a but can also be arranged in the horizontal pipe section 16b.

[0076] Further, in the device 10 which is shown in FIG. 2, a cyclone 20 is provided for separating liquid and gases flowing through the cyclone from the venting pipe 16e. The means 19 for establishing an underpressure can then be in communication, via the cyclone venting pipeline 16f, with the cyclone 20.

[0077] FIG. 2 shows that the first and second volumes of liquid are different, i.e., the liquid is transported through the device 10 to exchange gases and to remove foam and particles in the liquid, while the bulk of the liquid is conducted via the downstream pipeline 16c from liquid volume A to liquid volume B.

[0078] FIG. 3 shows an embodiment of the present invention, i.e. where the horizontal pipe section 16b is fitted with several sections for extracting gases (and smaller amounts of liquid) from the pipe section 16b. In the embodiment which is shown in FIG. 3, the device 10 is provided with a cyclone 20 for the separation of gases and liquid discharged from the venting pipe section 16e, but the device will also function without such a cyclone 20. In some embodiments there is more than cyclone 20 being used. The means 19 is the central fan or vacuum pump which constantly causes an underpressure in the pipeline 16 and provides gas extraction, and a section of liquid, from the pipe sections 16e, optionally via pipe section 16f from the cyclone 20.

[0079] The liquid is transported via the inlet pipe section 16a and through the pipe section 16 to an outlet via the pipe section 16c. One or more injectors/ejectors 17 are provided in the pipeline 16, preferably in the lower section of the pipeline 16 and in the pipeline section 16b. It is preferred that a pump that supplies liquid, preferably water, to the injectors/ejectors 17 is connected to the injectors/ejectors 17. Also connected to the injectors/ejectors 17 is an open-air hose for the supply of air into the ejectors 17. This occurs with a venturi when water flows through the nozzles.

[0080] As shown in FIG. 3, the present invention comprises several sections 16e where gases, particles and a portion of liquid are separated from the liquid stream which is taken in through the pipe section 16a, i.e., the gases/liquid/particles that are discharged from the pipe section 16b via the pipe section 16e are purified for gases, particles and foam in several subsequent purification steps. In FIG. 3, the different pipe sections 16d are shown as 16d, 16d′, 16d″ and 16d′″. The pipe section 16d and transfer to the pipe section 16e show the first cleaning step (i.e., as also shown in FIGS. 1 and 2), while the pipe sections 16d′, 16e′ show the second cleaning step, and the pipe sections 16d″, 16e″ show the third cleaning step, and 16d′″, 16e′″ show the fourth cleaning step. The final cleaning step, in this embodiment, is carried out in the cyclone 20. The solution according to the invention can comprise two or more such cleaning steps. Optionally, the embodiment of the invention can comprise more cleaning steps than those that are shown in FIG. 3.

[0081] Thus, the pipe section 16b is fitted with several pipe sections 16d, 16d′, 16d″, 16d′″, so that the liquid which flows through the pipe section 16b can be discharged via a number of pipe sections 16d. In each of these, there is a venting section so that gases, particles, foam, and some liquid are vented and fed via pipelines 16e, 16e′, 16e″, 16e′″ out of the pipeline 20, optionally via the cyclone 20 and the pipe section 16f. The pipe sections 16d, 16d′, 16d″, 16d′″ have an, in the main, a vertical configuration, but sections of the pipe sections 16d, 16d′, 16d″, 16d′″ can be inclined as shown in FIG. 3. In the pipe sections 16d, 16d′, 16d″, 16d′″, water is collected with foam and particles and sucked into the drains, i.e. the pipe sections 16e, 16e′, 16e″, 16e′″. Gases/particles/liquid which are discharged from device 10 can be connected and collected in one pipeline, as shown in FIG. 3, and be fed together to the cyclone 20.

[0082] It is preferred, as shown in FIG. 3, that the device comprises a number of ejectors 17. As mentioned, an injector/ejector 17 is preferably arranged in the lower section of the pipeline 16a. Experimental testing of the device according to the invention has also shown that it is advantageous to arrange an injector/ejector 17 just downstream of each of the suction towers, i.e. just downstream of each pipe section 16d, 16d′, 16d″, 16d′″.

[0083] It is also preferred that each of the sucking out towers (i.e. the pipe sections 16d, 16d′, 16d″, 16d′″) are fitted with respective valves 25, 25′, 25″, 25′″ for control of the pressure.

[0084] FIG. 4 shows a solution in which the venting sections 16d are in the form of elongated ducts. In principle, the venting sections 16d in the pipe section 16b can have any shape. Particularly preferred is the circular shape as indicated above and shown, inter alia, in FIG. 3. It is also preferred that the venting sections have a rectangular shape and that they are elongated in the longitudinal direction of the pipe section 16b. In this way, they will form venting ducts 16h.

[0085] In a preferred embodiment of the invention, the device 10 is provided with only one such venting duct 16h, preferably of a rectangular shape.

[0086] In other preferred embodiments, several such venting ducts 16h are provided, and where the gas vented from these venting ducts 16h is brought together to the cyclone 20. It is preferred that where the venting duct (16h) is formed as an external top section (16h), relative to the pipeline (16b) i.e., which is a rectangular longitudinal box which is external to the pipe section 16b.

[0087] Further, one or more wall sections of the top section, i.e. of the venting duct (16h), can be adjusted so that the opening in the venting duct can be adjusted so that it can regulate how much foam/liquid is sucked out.

[0088] FIG. 5 shows in cross-section an embodiment of pipeline 16b, i.e., that pipeline 16b need not have a circular pipe form. The figure shows a rectangular pipeline 16b. This can, for example, be built as a square profile, i.e., a carrier that is readily in steel or aluminum, or other material. Then the device itself will be able to carry its own weight with water, equipment and walkway, without support. The pipes 16e can then enter a connection rod which is an integral part of this carrier 16b. It can have several integrated runs of water for ejectors 17, water out of the air towers 16d and the pipe 16b itself, as a multi-channel carrier.

[0089] From tests we have found that we get the foam drained out and particles and air for each suction tower, and that by injecting new microbubbles right after each tower, we get new air that is not saturated with CO.sub.2 and particles, and get thereby an approximate n×improvement, where n is the number of towers/injections. The amount of CO.sub.2 in the water will gradually be reduced as it passes through the towers, and approach asymptotically with the natural CO.sub.2 level which is just below 1 mg/L water. In fishing tanks, the CO.sub.2 level is often between 10-15 mg/L.

[0090] The principles of the invention have been confirmed by full scale testing where the device 10 is fitted such that it raises water from the centre of a tank and passes it out and down into an outer segment of the tank. A vacuum pump 19 of an underpressure of 300 mbar will be able to lift the water 3 m up in the pipes. By adjusting the valves 25 one can regulate how high the water is in the individual 16d depending on the height of the horizontal pipe 16b for the individual installation. The horizontal pipe 16b was at a height of 2 m, while connection to the vacuum pump 19 was at a height of 3.5 m. Ejectors 17 fitted 1 m below the water surface at the bottom of the riser 16a, driven by water (30 l/min) at a pressure of 2.5 bar, sucked in air and created microbubbles which were fed to the pipe section 16a. These air bubbles make the water weight in the riser 16a lighter than in the downpipe 16c, thus creating circulation in the pipeline 16. These act as a “syphon”. The water flow out of the pipe 16c into the outer ring volume was measured at 330 l/min. The pipe dimension was 110 mm diameter.

[0091] At the same time, the air was sucked up in the vent together with foam which was formed by the microbubbles and particles in the water. The foam was separated and drained out as water in the cyclone 20. The experiment was conducted on pure seawater. After 5 min operation we drained 1 litre of water from the cyclone. Samples of this were sent for analysis as this was clearly discoloured. It had a turbidity of FNU 20-30, where the majority of the particles had a size of 2-10 μm.

[0092] At the same time, the gas level was measured at the inlet and in the outlet. This showed a drop in gas pressure from 100% to 95%. This confirms that the method is effective both for the removal of gases (especially CO.sub.2 since it is easily soluble in water) and the smallest particles, in the same process of moving the water from one place to another. This is therefore also a very energy efficient method.