DK2631368T3 - Method and device for noise reduction - Google Patents

Description

Method and device for acoustic insulation Description

The invention relates to a sound insulation apparatus for pile driving under water, having at least one line which can be fixed on the seabed which has a plurality of holes and also at least one compressor, by way of which compressed air can be introduced into the line, with the result that said compressed air can exit from the holes. Furthermore, the invention relates to a method for reducing the transmission of sound in a liquid comprising the following steps: deploying a line onto the seabed, which line encloses the sound source in an annular manner and is provided with holes, and introducing compressed air into the line, with the result that said compressed air exits through the holes.

Apparatus and methods of this kind can be used for sound insulation when driving cylindrical piles into the seabed. Piles of this kind can be used to anchor monopole, tripod, tripile or jacket constructions, on which structures such as wind measurement masts, wind turbines, drilling rigs or substations can be established in the offshore region.

The aforementioned foundation structures can be largely prefabricated on land, so that they can be installed simply and quickly on site in often difficult weather conditions. It is disadvantageous, however, that heavy piling implements are needed for the erection which introduce a high sound level of more than 130 dB, for example, into the environment. Sound levels of this kind may be harmful to marine fauna.

It is therefore known from DE 10 2004 043 128 A1 for compressed air to be conducted through a pipe system surrounding the pile driving site, which air can escape through holes in the pipes. However, since the line has great buoyancy because of the air it contains, these measures can only be carried out in a time-consuming manner. For example, the line can be secured to the seabed by divers, in order to prevent it from floating upwards during operation. Once the building work has been completed, the line must either be abandoned or released from the sea bed by deploying divers once again. Alternatively, the line can be loaded with external weights, although this makes it more difficult to handle.

The problem addressed by the invention is therefore that of specifying a device and a method for pile driving under water which combines a good sound insulation effect with low expenditure on apparatus, so that the sound insulation measures can be carried out quickly and easily.

The problem is solved by a sound insulation apparatus according to Claim 1, a hose according to Claim 8 and also a method according to Claim 12.

It is proposed according to the invention, for sound insulation during pile driving, for air bubbles to be allowed to rise in a manner known per se from a line which surrounds the pile driving site in a roughly annular manner. Due to the inhomogeneity of density between the rising air bubbles and the surrounding seawater and also the compressibility of the air bubbles, the energy of the soundwaves can be at least partially dissipated, so that a smaller sound intensity prevails outside the curtain of bubbles. In order to achieve a sound reduction in all directions, the line can be deployed in such a manner that it completely encloses the pile driving site in annular fashion. Insofar as a reduction is only necessary in certain directions, the line can of course only be laid in these directions or else the ring around the pile driving site may not be completely closed.

The compressed air emerging from the line is supplied by at least one compressor which is usually mounted on a ship or a jack-up barge on the water surface. The compressed ambient air is then fed to the line via a supply hose and leaves the line via a plurality of holes which are introduced along the longitudinal extent of the line.

Since the line is therefore completely full of air when the apparatus is running, buoyancy forces act on the line. In order for the sound insulation apparatus to function, however, it is necessary for the line to remain lying on the seabed. Otherwise, the sound emanating from the piling driving can pass unhindered between the line and the seabed and can therefore be propagated with full intensity.

It is proposed according to the invention that a ballast body should be introduced into the line. In this way, the total weight of the line is increased to such an extent that it remains lying on the seabed without further anchoring or additional external weights. Since the ballast body is attached within the line, the outer shape of the line remains unchanged, which means that it can still be recovered and/or deployed, without external weights obstructing the process. Anchoring by drivers can also take place in addition, although this is not usually necessary. The number of anchors can at least be reduced or the spacing of the anchoring points increased, as the line remains lying on the seabed due to its high dead weight.

In some embodiments of the invention, the ballast body may comprise a metal or an alloy. In other embodiments of the invention, the ballast may comprise a mineral material or consist thereof, for example concrete. During production of the line, for example by extrusion, the ballast body or ballast bodies can be directly introduced into said line. For example, ballast bodies can be bonded, screwed or riveted in at certain intervals in the line. In another embodiment of the invention, a plurality of ballast bodies can be connected to one another using a cable or a chain which prevent slippage along the longitudinal extent of the line. In one embodiment of the invention, at least one chain of sufficient size can be used with a plurality of chain links as a single ballast body. A ballast body of this kind can easily be introduced into the line. The movability of the chain links means that the ballast body does not obstruct the rolling up and unrolling of the line, or only to a negligible extent.

In some embodiments of the invention, the line may have at least one length section which has a hose with a wall, the wall comprising at least one layer of a wire mesh. In some embodiments of the invention, a plurality of layers of a wire mesh may be present in the wall. In some embodiments of the invention, the number of layers of the wire mesh may be between 1 and 8, between 2 and 7 or between 3 and 5. The wire mesh in the wall of the hose increases the tensile strength thereof, so that mechanical damage or a cross-sectional or length change that does not fall within tolerances is avoided when unwinding the hose. Furthermore, the wire mesh can restrict the elasticity of the hose, so that this retains its desired cross section, even with a high excess pressure. Consequently, the apparatus can be operated with greater reliability and deployed and recovered particularly safely.

In some embodiments of the invention, the wire mesh and/or the chain or the at least one ballast body may comprise stainless steel or consist thereof. For the purposes of the present description, stainless steel should be understood to mean an alloyed steel which is corrosion-resistant or at least corrosion-inert. For example, steels with the material numbers 1.4401, 1.4571 or 1.4462 can be used. The use of these stainless steels extends the service life of the proposed apparatus in the event that the air outlet openings or damage to the wall causes sea water to come into contact with the ballast body and/or the wire mesh.

In some embodiments of the invention, the sound insulation apparatus furthermore contains at least one winding apparatus with at least one drum onto which the line can be wound. In some embodiments of the invention, the drum may exhibit a drive, for example an electrical or hydraulic drive. The drum may be set up so that more than approximately 900 m, more than approximately 1000 m or more than approximately 1100 m of line can be wound on. Using the proposed winding apparatus, the line can be unrolled in a similar manner to an anchor chain from on board a working ship and laid on the seabed. Provided the ship tracks a circle around the pile driving site during this, all spatial directions of the sound propagation can be covered.

In order to take up the line following completion of the work, in some embodiments of the invention it may be sufficient for the line to be rolled onto the drum, while the ship drifts substantially without propulsion or with a small engine output. In this way, the ship is guided by the line as with an anchor chain and follows the course of the line backwards, while the line is wound onto the drum. In particular with this type of deployment and recovery of the line, a line with greater tensile strength proves successful, as in the proposed embodiment with at least one wire mesh in the wall. The ballast body can also be used to absorb tensile forces when said ballast body comprises a chain or a wire cable or consists thereof.

In some embodiments of the invention, a plurality of lines can be deployed at the same time, said lines enclosing the sound source in an annular fashion in each case. In this way, a plurality of roughly concentrically arranged curtains of bubbles is formed. Because a single curtain of bubbles from a single line causes a reduction in sound of approximately 12 dB to approximately 20 dB, a plurality of bubble curtains means that a correspondingly greater reduction can take place. To the extent that a plurality of lines is deployed at the same time, this improved sound insulation can be installed with a single journey of the ship about the pile driving site. In some embodiments of the invention, the number of lines deployed at the same time is approximately 2 to approximately 6.

In some embodiments of the invention, a plurality of lines can be deployed at the same time, in that each line is unwound from an associated winding device which unwinds the lines at a different speed. Insofar as the winding devices each have drums with the same diameter, different rotational speeds can be chosen for this purpose. It was recognized according to the invention that the lines in this case come to rest on the seabed in a spaced-out manner. For example, the speed in some embodiments of the invention can be chosen in such a manner that the lines are arranged substantially concentrically, wherein the outer line is laid with a radius which is approximately 10 m to approximately 30 m greater than the radius of the inner line.

In some embodiments of the invention, the drum of the winding device may have an internal air supply, so that the line can be loaded with compressed air during unwinding and/or during recovery. In this way, the line is not only mechanically stabilized, so that it does not experience any inadmissibly small bending radii which could damage the line. Furthermore, the penetration of seawater and sand which could lead to the blockage of individual holes in the wall of the line is avoided.

The invention is to be explained in greater detail below with the help of figures without limiting the general principle underlying the invention. In the figures:

Figure 1 shows an exemplary embodiment of a proposed line according to the invention.

Figure 2 shows a connecting element for two line parts according to an embodiment of the invention.

Figure 3 shows a winding apparatus according to an embodiment of the invention.

Figure 4 shows the cross section through a line.

Figure 5 illustrates the functional principle of the proposed sound insulation apparatus.

Figure 1 shows a hose 11 which can be used as a line 10 in a sound insulation apparatus 1 according to the invention. In this case, the hose 11 may form at least one length section of in the line 10. In other embodiments of the invention, the line 10 may be completely formed by the proposed hose.

The hose 11 has a wall 111 which is explained in greater detail with the help of Figure 4. The wall 111 defines the clear span 116 of the hose 11. The wall 111 may be produced from a rubber or a polymer. For example, the wall 111 may comprise polyvinyl chloride or EPDM or consist thereof. In order to improve the tensile strength and the compressive strength of the hose 11, the wall 111 may comprise at least one wire mesh 112, 113 or 114. Figure 4 shows an embodiment with three approximately concentrically arranged layers of wire mesh. These can be inserted into the wall 111 during the extrusion or vulcanization of the hose 12. In other embodiments of the invention, the number of wire meshes 112, 113 and 114 may be greater or also smaller and be between approximately 1 and approximately 7. In some embodiments of the invention, wire mesh can also be dispensed with.

The wall 111 has a plurality of holes 105, one of which is depicted in cross section in Figure 4. The holes 105 may have a diameter of approximately 0.5 to approximately 5 mm. The holes 105 may be arranged at intervals of approximately 100 cm to approximately 10 cm in the wall 111.

On the inside 115 of the wall 111, there is at least one ballast body which balances the uplift of the hose 111 to such an extent that said hose remains lying on the seabed, even if the remaining clear span 116 of the hose 11 is filled with compressed air. As explained with the help of Figure 1, a chain with a plurality of chain links 102 is used as the ballast body 101 in the exemplary embodiment shown. In an embodiment of this kind, the hose 11 or else the line 10 still remains flexible, so that it can easily be unrolled and rolled up and thereby laid on the seabed in a particularly simple manner and removed from there again. Even if the chain 101 can fill a large part of the clear span 116, the compressed air can still flow through the line 10 between the links 102. Furthermore, just as in the case of the wire mesh 112, 113 and 114, the chain 101 can further increase the tensile strength of the line 11, so that damage is avoided when the line 10 is deployed and recovered.

The wire mesh 112, 113 and 114 and also the chain 101 or else another ballast body may be produced in some embodiments of the invention from corrosion-inert or corrosion-resistant steel. In this way, the service life of the line 10 is extended if, during operation of the apparatus, sea water should enter through damage points or through the holes 105.

Figure 2 shows a connecting element 40, with which different length sections of a hose 11 can be assembled into a single line 10. The connecting element 40 has a sleeve 41. The sleeve 41 comprises a cylindrical base body on the outside of which a plurality of ribs 45 is arranged. The outer diameter of the cylindrical base body 41 roughly corresponds to the clear span 116 of the hose 11. In this way, the hose 11 can receive the cylindrical base body 41, wherein the ribs 45 come to lie on the inner wall 115.

Once two hoses have been located on the base body 41 from both sides, the joint can be inserted into a clip 43 configured as a half-shell. The clip 43 is then closed via holes 44 using a screw connection 47.

Optionally, the clip 43 may exhibit recesses or ribs 46 which are formed or arranged to match the ribs 45. In this way, a form-fitting connection of the hose 11 to the cylindrical base body 41 is achieved, so that high tensile forces in the direction of the length section of the hose 11 can be transmitted without the hose 11 slipping out of the connecting element 40.

Figure 5 shows a sample application of the sound insulation method or the sound insulation apparatus proposed according to the invention. Figure 5 shows the tower of a wind turbine 3 which is anchored to the seabed 2 by means of a tripod 30. The water depth at the installation site of the wind turbine 3 may be approximately 10 m to approximately 45 m or approximately 25 to approximately 40 m, for example.

The tripod 30 has assembly sleeves 31 on its base points. The assembly sleeves 31 are provided to receive a driven pile 32. Insofar as the tripod 30 is securely connected to the driven piles 32 and the driven piles 33 are securely anchored in the seabed 2, the wind turbine 3 is reliably located on the seabed 2. For this purpose, the driven piles 32 may have a diameter of approximately 2 m to approximately 5 m and a length of approximately 20 m to approximately 40 m.

The driven piles 32 are driven in using a pile driver which is not shown, wherein high-intensity sound emissions 21 are produced which are propagated as structure-borne sound in the sea water.

In order to reduce damage to marine fauna by sound emission 21, it is proposed according to the invention that a line 10 should be deployed in an annular shape around the pile driving site or around the entire tripod 30 with all pile driving sites. For this purpose, the line 10 is unrolled from a winding apparatus 15 according to the invention, which is mounted on a ship 11 and is described in greater detail with the help of Figure 3. Once the ship 11 has sailed around the construction site once and has unrolled the line 10 during this, said line lies on the seabed 2 as a result of its dead weight. In order to reduce the penetration of salt water into the clear span 116 of the line 10 and/or to stabilize the line 10 mechanically, the line 10 can be loaded with compressed air from the compressor 18 even during deployment. On account of the ballast body within the line 10, said line sinks as a result of its own weight to the seabed.

Before the piling work begins, the line 10 is loaded with compressed air by at least one compressor 18 and a line 181. The compressed air 180 leaves the line 10 through the openings 105 and rises in the form of bubbles to the surface of the sea. The high intensity sound emission 21 is attenuated during the passage through this curtain of bubbles 180, so that a lower sound intensity 22 can be perceived outside the area delimited by the line 10.

Upon completion of the work, the line 10 can be hauled on board the ship 11 again with the help of the winding apparatus 15 and is then available for the next deployment. In order to recover the line 10, the ship 11 can drift without propulsion or with a low engine output, while the line 10 is recovered using the winding apparatus 15. This leads to the ship 11 following the line 10, as when an anchor chain is being hauled in, so that bending loads on the line 10 or the winding of the tripod 30 with the line 10 is avoided.

The function of the winding apparatus 15 is described with the help of Figure 3. The winding apparatus 15 has a frame 151. The frame 151 may exhibit the external dimensions of a traditional container, for example the dimensions of a freight container in accordance with ISO 668. In this way, the winding apparatus 15 can be transported and stored in a space-saving manner.

Insofar as the frame 151 exhibits the standard dimensions of a freight container, it may also exhibit the connecting elements 153 of a container of this kind, so that a plurality of pieces of winding apparatus 15 can be stacked on top of one another like containers or mixed stacks made up of winding apparatus 15 and containers can be formed. This makes space-saving, cost-effective transport possible on the ship 11. A drum 152 is mounted rotatably within the frame 151. The drum 152 may be designed to receive more than 500 m, more than 900 m, more than 1000 m or more than 1100 m of the hose 11. Since the hose 11 is produced from a flexible rubber or plastic and has a smooth outside due to the ballast bodies arranged inside, the hose 11 can be mounted on the drum 151 in a particularly space-saving manner.

In order to recover the hose 11, the drum 152 may be rotated using a hydraulic drive which is not shown, so that the hose 11 is unrolled while the ship 19 circles the area provided for the sound insulation measures. Insofar as the drive of the drums 152 is sufficiently large in size, the ship 19 can be pulled backwards on the hose 11 in order to recover the hose 11, wherein the hose 11 is wound on the drum 152.

Furthermore, a compressed air connection 154 can be seen in Figure 3. The line of a compressor 18 can be attached to the connection 154, which compressor loads the line 11 with compressed air. Due to the compressed air connection of the hose 11 lying inside the drum, the hose 11 can be loaded with compressed air even during unrolling.

The invention is not, of course, limited to the embodiments shown in the figures. The above description should not therefore be regarded as limiting, but as explanatory. The following claims should be understood in such a manner that a specified feature is present in at least one embodiment of the invention. This does not preclude the presence of further features.

Claims (15)

A noise suppression device (1) for underwater piloting works having at least one cable (10) fixable on the seabed (2) with a wall (111) showing a plurality of bores (105) and enclosing a free width ( 116), and with at least one compressor (18) by which compressed air (180) can be introduced into the conduit (10) so that it can flow out of the bores (105), characterized in that the conduit has at least one longitudinal section, in which a weight body (101) is disposed within the free width (16). Noise-canceling device according to claim 1, characterized in that the weight body (101) contains or consists of a chain. Noise-canceling device according to claim 1 or 2, characterized in that the conduit (10) has at least one longitudinal section showing a hose (11) with a wall (111), wherein the wall (111) contains at least one layer of a wire mesh (112,113,114 ), or that the wall (111) contains between 2 and 7 layers of a wire mesh (112, 113, 114), or that the wall (111) contains between 3 and 5 layers of the wire mesh (112, 113, 114). Noise-canceling device according to one of claims 2 or 3, characterized in that the wire mesh (112, 113, 114) and / or the chain contains or consists of a stainless steel. The noise suppression device according to one of claims 1 to 4, further comprising a winding device (15) with a drum (152) on which the line (10) can be wound. The noise suppression device of claim 5, further comprising a hydraulic drive mechanism by which the drum (152) can be operated and / or that more than about 900 m, more than about 1000 m, or more than about 1100 m of drain (10) can be wound on the drum (152). Noise canceling device according to one of claims 5 to 6, characterized in that the winding device (15) has a frame (151) whose outer dimensions have the size and / or connecting elements (153) of a shipping container, for example a shipping container according to ISO 668. Hose with a wall (111) enclosing a free width (116), the wall (111) exhibiting a plurality of bores (105), characterized in that at least one longitudinal section of the hose in the free width (116) ) a weight body (101) is introduced. Hose according to claim 8, characterized in that the weight body (101) contains or consists of a chain. Hose according to one of claims 8 or 9, characterized in that the wall (111) contains at least one layer of a wire mesh (112, 113, 114) or that the wall (111) contains between 2 and 7 layers of the wire mesh (112). , 113, 114) or that the wall (111) contains between 3 and 5 layers of the wire mesh (112, 113, 114). Hose according to one of claims 8 to 10, characterized in that the wire mesh (112, 113, 114) and / or the chain (101) contain or consist of a stainless steel. A method for reducing the transmission of noise in a liquid, comprising the following steps: laying at least one conduit (10) on the seabed (2) enclosing the noise source annularly and provided with bores (105), introducing compressed air (180) in the at least one conduit (10) so that it flows out through the bores (105), characterized in that - the conduit is wound by means of a winding device (15) and exhibits at least one longitudinal section into which a weight cc (101) is introduced. so that, due to its own weight, it will lie on the seabed (2), and / or - at the same time, several wires are laid out, each enclosing the noise source annularly. The method according to claim 12, characterized in that the winding device (15) is mounted on a ship (11) which at least during the inhalation drives the drain around without driving force. Method according to one of claims 12 or 13, characterized in that the winding device (15) is provided with a drum (152) on which the conduit (10) is wound and which has an internal air supply (154), so that the conduit (10) during run-off and / or during inhalation may be affected by compressed air. Method according to one of claims 12 to 14, characterized in that at least two wires are laid out at the same time, each wire being rolled from an associated drum and both drums having different rotational speeds.