Abstract:
A method for storing and/or transporting a plurality of objects ( 5   a,    5   b ) for one or more wind turbines is presented, the method comprising arranging a first object ( 5   a ) to be supported by a plurality of wheels( 901 ), arranging a second object ( 5   a ) to be supported by a plurality of wheels( 901 ), rolling the first object into a first location( 13   a ), subsequently raising the first object to a second location ( 13   b ) above the first location, and subsequently rolling the second object into the first location, thereby inserting the second object under the first object.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to methods for storing and/or transporting a plurality of objects for one or more wind turbines, and a method for storing and/or transporting a plurality of objects. 
       BACKGROUND OF THE INVENTION 
       [0002]    There is a trend of new wind turbine models having increased rated power, and this increases the sizes of the turbines. The total weight of some modern offshore wind turbines amount to hundreds of tons, and in some cases the total weight of the blades only exceed a hundred tons. 
         [0003]    Normally, before wind turbines are installed, their components, such as towers, blades and nacelles, are manufacturing at separate factories, after which the components are transported to the wind turbine erection sites. In addition some components, like towers, can be transported separated into sub-components, for example tower sections, from factories to assembly sites, at which the sub-components are assembled into components which are sent to the installation sites. Wind turbine tower sections are usually assembled by bolting flanges at the tower section ends together. 
         [0004]    Transportation of wind turbine components usually takes place on roads, on railroad or at sea. The increasing sizes of wind turbine models mean that the sizes of their components increase as well. This causes challenges to their transportation. 
         [0005]    For transport of wing turbine tower sections, a transport frame can be bolted onto the flange at each tower section end; DE202012009278U1 shows an example of such a frame. WO2007093854A2 discloses an example of an alternative device to be mounted to tower section flanges for tower transport. Similarly, for blades a transport frame can be bolted onto a flange at the blade root end, and another frame can be mounted somewhere between the tip of the blade and the blade centre of gravity. 
         [0006]    Stacking components on top of each other can be useful to save floor space on the transporting vehicle or vessel, and to increase carrying capacity. For example, towers sections for a plurality of towers, or blades for a plurality of wind turbines, can be stowed on the deck of a sea vessel, or onto a train. Thereby, frames of the type mentioned above can be used for stacking the tower sections or the blades on top of each other. Examples of such stacking for tower sections are shown in EP2360372A1, US2008232920A1, WO2007093854A2 and WO2010012280A1, and for blades in WO2011076238A1. 
         [0007]    Moving wind turbine components onto or off from a vessel or a vehicle is usually done with a crane. Also stacking of wind turbine components is usually done with a crane. Due to the increasing sizes of the components, large capacity cranes are needed at the site at which handling takes place. This adds to the complexity and planning of the transport handling procedures. In particular, the large cranes with the capacity needed for some wind turbine components might cause ground capacity problems, for example at harbour quays for loading components onto a sea vessel. 
         [0008]    A way to avoid cranes when loading components onto or off from a vessel (e.g. a sea vessel) or a vehicle (e.g. a road truck or a railway vehicle) is to use a roll-on-roll-off system, i.e. a system where support devices with wheels are secured to the transported components, and the components with the support devices are rolled onto or off from vessel or vehicle. For example, a sea vessel can be provided in the form of a roll-on-roll-off ship (RoRo ship), which has a loading area which is accessible from a quay and allows the cargo to be rolled on and off the ship. 
         [0009]    A problem with roll-on-roll-off systems is that they do not allow for stacking components without the use of a crane. However, as stated cranes can entail added complexity and planning of the transport handling procedures. 
         [0010]    The discussion above focuses on transportation of wind turbine components, but similar considerations and problems can appear for storing wind turbine components. 
       SUMMARY 
       [0011]    It is an object of the invention to improve wind turbine component handling. It is another object of the invention to reduce crane lifting operations in wind turbine component handling. It is a further object of the invention to increase the carrying capacity of wind turbine component transport vehicles and vessels. It is yet another object of the invention to facilitate transportation of large wind turbine components. 
         [0012]    These objects are solved by a method for storing and/or transporting a plurality of objects for one or more wind turbines, the method comprising
       arranging a first object to be supported by a plurality of wheels, and   arranging a second object to be supported by a plurality of wheels, the method further comprising   rolling the first object into a first location,   subsequently raising the first object to a second location above the first location, and   subsequently rolling the second object into the first location, thereby inserting the second object under the first object.       
 
         [0018]    By rolling the first wind turbine object into the first position and then subsequently raising the first object to the second location above the first location, enough to insert the second wind turbine object under the first object, the raising of the first object can be a short, local and relatively limited vertical movement. Therefore, the first object can be raised with an arrangement provided adjacent to, or in the direct vicinity of the first location. Thus, this arrangement can be simple and specialised for this particular raising step, and the stacking of the first and second objects can be done without a crane. Thereby, stacking of transported wind turbine components is allowed, while not adding to the complexity of the transport handling procedures. Thereby, transportation of large wind turbine components is facilitated, and wind turbine component handling is improved. 
         [0019]    A particular advantage of the invention is that it allows for the objects to be rolled onto the vessel or vehicle individually, and then stacked on top of each other once on the vessel or vehicle, without the use of a crane. It should be noted however that the invention can also be used for stacking the objects 
         [0020]    As exemplified below with reference to the figures, it is understood that for undoing the stacking of the first and second objects, essentially the steps mentioned above are carried out in a reverse order, i.e. the second object is rolled away from the first location, the first object is lowered to the first location, and the first object is rolled away from the first location. 
         [0021]    The steps of arranging the first and second objects to be supported by a plurality of wheels can be performed in a number of alternative ways. The first and second objects can be placed onto multi-axle trailers or self-propelled modular trailers (SPMTs), or one or more handling interface devices, (examples of which are discussed below), with wheels can be mounted onto the first and second objects. 
         [0022]    Preferably, after rolling the second object into the first location, the first object is lowered so as to be supported by the second object or one or more handling interface device, such as frames, (examples of which are discussed below), mounted to the second object. Preferably, the first location is on a vehicle or a vessel and the first and second objects are rolled onto the vehicle or the vessel before being rolled into the first location. 
         [0023]    Preferably, the method comprises mounting to each of the first and second objects at least one handling interface device, as exemplified below with reference to the figures. For example, for each object there could be one handling interface device in the form of a cradle, or there could be two handling interface devices each in the form of a frame. 
         [0024]    Preferably, the at least one handling interface device mounted onto the first object presents a plurality of engagement elements, the method further comprising engaging a raising arrangement to the engagement elements, the step of raising the first object to the second location being carried out by means of the raising arrangement. 
         [0025]    Preferably, when the at least one handling interface is mounted on the first object, the engagement elements are arranged distributed around the centre of gravity of the first object. 
         [0026]    The engagement of the raising arrangement with the engagement elements is preferably done after the first object has been rolled into the first location. 
         [0027]    As exemplified below, the raising arrangement can comprise jack up devices, herein also referred to as jacks, arranged to push up the first object. Each jack up device is a mechanical device that can apply a linear force, and it comprises an actuation device such as a hydraulic cylinder or a screw thread. To “push” means here to use force to move something away from the actuation device directly causing the motion. 
         [0028]    Preferably, after rolling the second object into the first location, the first object is lowered so as to be supported by one or more handling interface devices mounted to the second object, and the handling interface devices are used to fix the first and second objects to each other after the step of lowering the first object onto the second object. 
         [0029]    Preferably, where the first and second objects are elongated objects, the method comprises mounting to each of the first and second objects at least two handling interface devices, each handling interface device mounted to the first object comprising at least one engagement element, preferably two engagement elements, the method further comprising engaging to each of the engagement elements a respective jack up device, the step of raising the first object to the second location being carried out by means of the jack up devices. 
         [0030]    Preferably, on each of the first and second objects, the two handling interface devices are mounted at opposite sides of centre of gravity, at two respective locations being separated in the longitudinal direction of the respective object. 
         [0031]    Preferably, each of the jack up devices presents an engagement device for engaging a respective of the engagement elements, at least one of the engagement devices being adapted to be rotated around a vertical axis. Thereby, as exemplified below with reference to the figures, where the jack up device is installed such that it cannot be rotated, the jack up device can still be used for raising objects on both sides of the jack up device, simply by swinging the engagement device to face either side of the jack up device. 
         [0032]    The method can further comprise
       arranging a third object to be supported by a plurality of wheels, for example by placing it onto an SPMT or mounting one or more handling interface devices with wheels thereon,   fixing the first and second objects to each other after lowering the first object onto the second object,   subsequently raising the first and second objects to the second location above the first location,   subsequently rolling the third object into the first location, thereby inserting the third object under the second object, and   subsequently lowering the first and second objects onto the third object.       
 
         [0038]    Thereby, the invention can advantageously be used for blades. Since most modern wind turbines have three blades, this can provide for arranging stacks with sets of three blades for a wind turbine. 
         [0039]    Similarly to what has been mentioned above regarding the first and second objects, where the first location is on a vehicle or a vessel, the third object can be rolled onto the vehicle or the vessel before being rolled into the first location. Also, the third objects can, like the first and second objects, be elongated objects, and the method can comprise mounting to the first, second and third objects at least two handling interface devices, each handling interface device mounted to the second object comprising at least one engagement element, preferably two engagement elements, the method further comprising engaging to each of the engagement elements of the handling interface devices mounted to the second object, a respective jack up device, the step of raising the first and second objects to the second location being carried out by means of the jack up devices. Thereby, the handling interface devices on the second and third objects can be used to fix the second and third objects to each other after the step of lowering the first a second objects onto the third object. 
         [0040]    Embodiments of another aspect of the invention are defined in claims  10 - 15 . 
         [0041]    A further aspect of the invention is defined in claim  16 , related to a method for storing and/or transporting a plurality of objects. Thereby, the method can be used for storing and/or transporting objects other than objects for wind turbines. 
     
    
     
       DESCRIPTION OF FIGURES 
         [0042]    Below embodiments of the invention will be described with reference to the drawings, in which 
           [0043]      FIG. 1  shows an offshore wind turbine, 
           [0044]      FIG. 2  is a perspective view of two tower sections with frames, and self-propelled modular trailers, 
           [0045]      FIG. 3  is a perspective view of one of the tower sections in  FIG. 2 , and a sea vessel, 
           [0046]      FIG. 4  is a perspective view of a part of the tower section in  FIG. 3 , on board the vessel in  FIG. 3 , 
           [0047]      FIG. 5  is a perspective view of a part of the tower section in  FIG. 3 , on board the vessel in  FIG. 3 , and a jack for raising the tower section, 
           [0048]      FIG. 6  is a perspective view of the tower section in  FIG. 3  on board the vessel in  FIG. 3 , the tower being raised with jacks as the one shown in  FIG. 5 , 
           [0049]      FIG. 7  is a perspective view of both tower sections in  FIG. 2 , and the sea vessel in  FIG. 3 , 
           [0050]      FIG. 8  is a perspective view of the tower sections in  FIG. 7  on board the vessel in  FIG. 3 , 
           [0051]      FIG. 9 a    and  FIG. 9 b    show side views of alternative jacks to be used in embodiments of the method according to the invention, 
           [0052]      FIG. 10 a   - FIG. 10 d    show views of details for raising the raising the tower section in  FIG. 3 , 
           [0053]      FIG. 11  shows a wind turbine blade raised with jacks, and 
           [0054]      FIG. 12  and  FIG. 13  show perspective views of tower sections with respective alternatives to the frames shown in  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0055]      FIG. 1  shows an offshore wind turbine with three blades  2 . It should be mentioned that the invention is equally applicable to onshore wind turbines. The blades  2  are mounted to a hub  3 , forming together with the blades  2  a rotor. The hub  3  is in turn connected to a generator housed in a nacelle  4 . The nacelle  4  is mounted on top of a tower  5 , which in turn is mounted on an offshore foundation  6 . The nacelle  4  can be rotated around a vertical axis to as for the rotor to be oriented into the wind as the latter changes direction. The tower  6  comprises three tower sections  5   a,    5   b,    5   c,  which are mounted to each other at adjacent ends of the tower sections. The tower sections have internal flanges at their ends and they are connected to each other by bolts through adjacent flanges. 
         [0056]      FIG. 2  depicts two elongated objects in the form of a first tower section  5   a  and a second tower section  5   b,  both stored on land in a harbour area. The tower sections  5   a,    5   b,  made of steel, are intended for a wind turbine tower, and will be transferred to a sea vessel for transport to a tower assembly site. At each end of the first and second tower sections  5   a,    5   b,  a handling interface device  7  is mounted. Each handling interface device  7  is provided in the form of a steel frame  7  which is bolted onto respective internal flanges of the tower sections  5   a,    5   b.  The tower sections  5   a,    5   b  are supported by storage legs  8  detachably mounted to the handling interface device  7 . 
         [0057]    As can be seen in  FIG. 2 , in a first step of an embodiment of the method according to the invention, the first tower section  5   a  is arranged with a plurality of wheels  901 . This is done by placing the first tower section  5   a  onto two so called self-propelled modular trailers  9  (SPMTs). More particularly, the SPMTs  9  are driven, as indicated by the arrows A, into respective positions under a respective of the frames  7 , between the storage legs  8 . Each SPMT  9  comprises a chassis with a plurality of wheels  901 , and a load platform  902 , which can be raised and lowered with a hydraulic arrangement, as indicated by the double arrow B. Under the frames  7 , the load platforms  902  are raised so that the first tower section  5   a  is supported by the SPMTs  9 . 
         [0058]    As can be seen in  FIG. 3 , by means of the SPMTs  9 , the first tower section  5   a  is moved to a quay  10 , at which a so called roll-on-roll-off vessel (RoRo vessel)  11  is docked. The RoRo vessel  11  is a barge, but it can of course be any type of RoRo vessel. A ramp  12  is arranged to bridge a distance between the quay  10  and the vessel  11 . By means of the SPMTs  9 , the first tower section  5   a  is rolled onto the vessel  11 , and into a first location  13   a  on the vessel  11 . The first location  13   a  is between two skid beams  14  and sea fastening legs  15  described closer below. 
         [0059]    As can be seen in  FIG. 4 , in the first location  13   a,  the first tower section  5   a  is positioned so that lower corners  701  of the frames  7  are aligned with a respective sea fastening legs  15 . Thus, there are four sea fastening legs arranged at the first location  13   a,  although in  FIG. 4  only one sea fastening leg  15  is shown. Each sea fastening leg  15  is arranged to engage with a respective of the four lower corners  701  of the two frames  7  mounted on the tower section  5   a.  For this engagement, the load platforms  902  of the SPMTs  9  are lowered, so that upper ends  151  of the sea fastening legs  15  enter cavities of the respective lower corners  701  of the frames  7 . The frames  7  can be secured to the sea fastening legs  15  by so called twistlock fittings. 
         [0060]      FIG. 5  shows how one of the skid beams  14  supports a jack  16 , herein also referred to as a jack up device. Four such jacks  16 , together forming a raising arrangement, are used to raise the first tower section from the first location  13   a  to a second location above the first location. Although for this presentation, the jack  16  is not shown in  FIG. 4 , it is understood that the jacks  16  can already be in their respective locations, for raising the first tower section  5   a,  when the first tower section is placed in the first location  13   a.    
         [0061]    The four jacks  16  are arranged so that two jacks are placed at each frame  7 , on opposite sides of the respective frame  7 . Each jack  16  is mounted on top of a skid shoe  17 , which can be moved along the skid beam  14  by means of a wire  171  and an anchor  172 , as described closer below. Each jack  16  comprises a telescopic leg  161 , on top of which an engagement device in the form of a trunnion  162  is fixed. Each frame  7  presents two engagement elements  702  in the form of lugs  701  protruding on opposite sides of the first tower section  5   a.  The jacks  16  are aligned with a respective of the lugs  702 . In a manner that is closer described below, the jacks  16  extend, as indicated by the arrow D, so that the trunnions  162  engage the lugs  702 . 
         [0062]    In alternative embodiments the skid shoes  17  can be moved along the skid beam  14  by means of a self-drive system. Also, suitable alternatives to the trunnions  162  can be provided. 
         [0063]    Referring to  FIG. 6 , by extending the jacks  16  further, the jacks push up the first tower section  5   a,  which is raised from the first location  13   a  to the second location  13   b  above the first location. Thereby, the frames  7  are lifted from the sea fastening legs  15 . 
         [0064]    Reference is made to  FIG. 7 . In a manner similar to what has been described above, the second tower section  5   b  is arranged to be supported by a plurality of wheels  901  of SPMTs  9 , and rolled to the quay  10 , onto the vessel  11 , and into the first location  13   a,  as indicated by the arrow E. Thereby, the second tower section  5   b  is inserted under the first tower section  5   a,  which is held in the second location  13   b  by the jacks  16 . 
         [0065]    Reference is made to  FIG. 8 . In the first location  13   a,  the second tower section  5   b  is positioned so that lower corners  701  of the frames  7  are aligned with the respective sea fastening legs  15 . For engaging the frames  7  of the second tower section  5   b  to the sea fastening legs  15 , the load platforms of the SPMTs (not shown in  FIG. 8 ) are lowered, thereby lowering the second tower section  5   a,  as indicated by the arrow F, so that the upper ends  151  of the sea fastening legs  15  enter cavities of the respective lower corners  701  of the frames  7 . The frames  7  of the second tower section  5   b  are secured to the sea fastening legs  15  by twistlock fittings, or other suitable connection devices. 
         [0066]    Subsequently, by retracting the jacks  16  (not shown in  FIG. 8 ), the first tower section  5   a  is lowered, as indicated by the arrow G, onto the second tower section  5   b.  More specifically, by retracting the jacks  16 , the frames  7  mounted to the first tower section  5   a  are lowered onto the frames  7  mounted to the second tower section  5   b.  The frames  7  are connected by twistlock connections at the lower corners  701  of the frames  7  mounted to the first tower section  5   a,  and upper corners  703  of the frames  7  mounted to the second tower section  5   b.  Thereby, the first and second tower sections  5   a,    5   b  are safely stored on the vessel deck without the use of any crane. 
         [0067]    The arrangement for extending and retracting the telescopic legs  161  of the jacks can be provided in a number of alternative ways. For example, the telescopic legs  161  could be provided with a hydraulic cylinder and piston arrangement.  FIG. 9 a    and  FIG. 9 b    show two alternatives with wire operated telescopic legs  161 . In  FIG. 9 a   , a wire  164  extends from the lower end of an inner tube  163  of the leg  161 , around a pulley  165  mounted on the upper end of an outer tube  166  of the leg  161 , and to a motorised winch  167  in the skid shoe  17 . Reeling in the wire  164  with the winch  167  will cause the inner tube to move out of the outer tube so as for the telescopic leg  161  to be extended. In  FIG. 9 b   , the motorised winch is replaced with a hydraulic cylinder  168  arranged on the exterior of the leg  161 . The wire  164  is in  FIG. 9 b    extended around the two ends of the hydraulic cylinder  168  in such a way the an extension of the hydraulic cylinder  168  will cause the inner tube to move out of the outer tube so as for the telescopic leg  161  to be extended. 
         [0068]    When the first tower section  5   a  has been lowered onto the second tower section  5   b,  the jacks  16  are moved along the skid beams  14  to be used for stacking two further tower sections at a further location  13   c,  indicated in  FIG. 7 . Means for this movement of the jacks  16  is shown in  FIG. 6 . The two skid shoes  17  on each skid beam  14  are connected with a wire  173 , and on the other side of one of the two skid shoes  17  on one of the skid beams  14 , the anchor  172  is provided fixed to the skid beam  14 . The wire  171  connects the anchor  172  and the skid shoe  17  closest to the anchor  172 . The skid shoes  17  comprise motorised winches adapted to reel the wires  171 ,  173  in and out. Thereby, by suitable actuation of the motorised winches, the skid shoes  17  with the jacks can be moved to desired positions along the skid beams  14 . For flexibility of the system, the anchors  172  can be moved and mounted on in a large amount of alternative positions along the skid beams  14 . 
         [0069]    As can be seen in  FIG. 7 , the vessel  11  comprises a further skid beam  14 , thus presenting three parallel skid beams  14 . As can be seen in  FIG. 10 a   - FIG. 10 d   , the trunnion  162  on top on each jack  16  can be swung around a vertical axis, as indicated by the arrow H in  FIG. 10 c   . This provides for jacks  16  on the middle skid beam  14  to serve tower section stacking operations on both sides of the middle skid beam  14 . 
         [0070]    It is understood that for unloading the tower sections  5   a,    5   b  from the vessel, essentially the steps described above are carried out in a reverse order. Thus, the jacks  16  are placed so are to at the frames  7 , and extended so as to engage the lugs  702  of the frames  7  mounted to the first tower section  5   a.  The first tower section  5   a  is raised and thereby released from the second tower section  5   b.  SPMTs  9  are placed under the frames  7  of the second tower section  5   b,  and the load platforms  902  of the SPMTs are raised so as to raise the second tower section  5   b  and release it from the sea fastening legs  15 . The second tower section  5   b  is then moved away from the first location  13   a  and rolled off the vessel  11 . The jacks  16  are retracted to lower the first tower section  5   a  from the second location  13   b  into the first location  13   a,  so as for the frames  7  mounted to it to engage the sea fastening legs  15 . SPMTs are placed under the frames  7  on the first tower section  5   a,  and the load platforms  902  of the SPMTs are raised to release the first tower section  16  from the sea fastening legs  15 . Then the first tower section  16  is rolled away from the first location  13   a  and off the vessel  11 . 
         [0071]      FIG. 11  suggests how the invention can be used for objects in the form of wind turbine blades. A first blade  5   a  is provided with frames  7  used to support the first blade on SPMTs (not shown) as has been described above. The first blade  5   a  is rolled into a first position  13   a,  in which the frames  7  are engaged by jacks  16 , similarly to what has been described above. The jacks  16  are used to raise the first blade  5   a  to a second position  13   b.  Thereafter, a second blade (not shown) is rolled into the first position  13   a,  as indicated by the arrow I. The first blade  5   a  is lowered onto the second blade. Thereafter, for a stack of three blades for a three blades wind turbine, the jacks  16  are used to raise the first and second blades, and a third blade (not shown) is rolled into the first position  13   a.  The frames on the third blade are fixed to sea fastening legs (not shown), similarly as described above, and the first and second blades are lowered onto the third blade. 
         [0072]    It should be noted that the handling interface device  7  can, instead of a frame  7 , be provided in a number of alternative forms. For example, as depicted in  FIG. 12 , for each object  5   a,  in this case a tower section  5   a,  a handling interface device  7  can be provided in the form of a cradle  7  supporting the object. Such a cradle could be adapted to extend around the centre of gravity of the object, and it could present all engagement elements, e.g. lugs  702  as described above, needed for engagement of a number of jacks to raise the object from the first to the second position. In other embodiments, for each object, a number of handling interface devices can be provided, each in the form of a bracket presenting a single engagement element for engagement of a respective jack. In further embodiments, handling interface devices as disclosed in WO2007093854A2 can be used. 
         [0073]    It should also be noted that the arrangement of the objects to be supported by a plurality of wheels can be embodied in a number of alternative ways. For example, instead of used SPMTs as described above, the handling interface devices  7  can be provided with wheels. For example, as depicted in  FIG. 13 , for each object, in this case a tower section  5   a,  frames  7  are provided with wheels  901 . Alternatively, the handling interface device(s)  7  can be provided as a cradle with wheels, or brackets with wheels. Wheels fitted to the handling interface devices can be permanently mounted on said devices. 
         [0074]    It should be noted that as an alterative to moving the second object into the first location, thereby inserting the second object under the first object, the first object can be moved along the skid beams, while supported by the jack up devices, from the second location into a third location above the second object.