MX2008009736A - Geostationary anchoring and riser arrangement on a ship - Google Patents

Abstract

A geostationary anchoring and riser arrangement in a vessel comprises a rotating body (11), which is mounted in a vertical shaft (6) in the vessel (1) by axial and radial annular bearings (31, 32). Above the upper axial and radial bearing (31, 32) is mounted a dynamic primary seal (35), thereby establishing a dry space above the bearings, in the shaft (6). Under the bearing is mounted a secondary seal (41). A fluid manifold (28) is placed in the dry shaft space.

Description

ANCHORING DEVICE AND GEOSTATIONARY UP-DUCT TUBES IN A BOAT DESCRIPTION OF THE INVENTION The present invention relates to the extraction of offshore hydrocarbons with the use of a geostationary anchored vessel. Said vessel is anchored to the seabed by means of a body rotatably mounted on the vessel, a so-called tower from which mooring cables extend to the seabed. From the bottom of the boat, ascending pipes also ascend through the rotating body. These risers are connected to a fluid manifold mounted above the rotating body from which there are lines extending for transfer of fluids to tanks on board the vessel. An object of the invention is to provide an improved geostationary anchor and riser device on a ship, particularly a ship and a converted tank. The invention is especially developed in connection with a conversion of a tanker as specified in the parallel patent application of the same applicant: "Method for the conversion of a tanker", but is not limited to use in connection with the same The use of the solution according to the invention can either be considered in new systems or as a substitute for existing bearing systems. In accordance with the parallel application mentioned above, a tank ship with a hull containing tanks is provided. In the hull, in one or more of the tanks a vertical opening is made, structural elements in the hull such as frames and abutments are cut and part of the projected opening is removed. A cassette-like structure is provided with plate elements designed to fit and connect with the structural elements cut into the vertical opening, which cassette has a vertical through-shot. The cassette is inserted in the vertical opening cut out in the hull and connected via the plate elements with the cut structural elements, so that a structure is formed which is incorporated in the hull and forms part of the reinforcement of the surrounding hull. A body is rotatably mounted around a vertical axis in the vertical shot. The cassette is incorporated into the existing helmet in such a way that the reinforcement of the helmet is not damaged. The vertical shot can advantageously be provided with a lower cylindrical section and an upper cylindrical section extending in relation to the lower section, lower cylindrical section which in the state incorporated in the cassette will be located near or in the area of the bottom of the helmet, the body is rotatably mounted at the transition between the two sections. By assembling the body at the transition between the two sections, facing down on the hull, preferably near the area of the bottom of the hull, the hull reinforcement that exists in the bottom area of the hull is advantageously utilized. In the upper part of the body a fluid manifold can advantageously be placed in the shot. This provides the possibility of mounting the fluid manifold in a protected position under the main deck of the vessel in a dry working space at the top of the draft. The anchoring device and geostationary riser tubes in a vessel according to the invention comprises a body mounted on a vertical shot in the vessel, which body is rotatably mounted in a wet boat area about a vertical axis by means of axial bearings and segmented annular radial, body which has an upper side and a lower side, vertical guides for ascending tubes between the upper and lower side and is provided with a superposed fluid manifold connected to the risers, the device is characterized in that Above the axial / radial bearing a dynamic primary seal is mounted between the body and the draft and a secondary seal is mounted between the body and the draft under the axial / radial bearing. The dynamic primary seal allows the space in the shot above the rotationally mounted body (the tower) to remain as a dry space, when the fluid manifold can be assembled and to which it can have personal access. The secondary seal is preferably a static seal which only comes into operation when the dynamic primary seal is neutralized in order to provide access to the axial / radial bearing for maintenance and other work. The lashing cables can be connected to the rotatably mounted body via a structure (anchoring table) whereby a respective larger lever arm is obtained for the lashing cables in relation to the body. A fluid manifold column can be supported particularly advantageously in the draft by a central stem projecting from the upper side of the body. This central stem is advantageously provided with a surrounding operation cover around the upper side of the body and the individual riser is advantageously connected to a suitable block with an ESD valve (emergency disconnected) in a level with the operation cover. In an advantageous embodiment, the body rotatably mounted around a vertical axis is characterized in that it is constructed as a cylindrical plate structure with an upper side and a lower side, with a central stem projecting from the bottom side upwards through the upper side and surrounding the stem, between the lower side and the upper side, coverings distributed for ascending pipes, stem which is designed to support the fluid manifold. The support for a body in a vertical draft in a vessel comprises a segmented annular bearing with adjustable bearing segments, characterized in that the individual bearing segment contains a part of wear against the body, wear parts which can be lubricated under pressure, an intermediate part with a degree of resilience and a mechanical lower part adjustable in height against the shot / the boat. Said individual bearing segment design allows it to adapt to irregular parts in the helmet as well as to the movements of the hull that occur in the sea. The mechanically adjustable height part of the bottom in the bearing segment allows adjustments to be made during assembly and dismantling of the bearing segment. Therefore, by moving the Bearing segment The lower part can be adjusted so that the load in the bearing segment is released in relation to the body so it is allowed to be removed and reinserted or easily replaced with a new one. A mechanically adjustable, height-preferred mode of the lower part in particular is that in which the lower part contains an interaction wedge that can be moved relative to one another for a height adjustment. By moving the wedges one in relation to the other, one can obtain the desired adjustment of the height of the bearing segment. The devices in addition to the wedge solution can be considered for adjusting the height of the bearing segments. In a particularly advantageous embodiment, the bearing can be placed in a system for pressurizing a medium suitable for lubricating the bearing support segments. In the lubricating medium they can be, for example, lubricants known per se, but also advantageously it can be pressurized water, particularly when some "lifting" of the body with respect to the annular bearing is required, a film is formed between the body and the segments of the lubricant. bearing. Pressure lubrication is important to avoid excessive "drag" of the body rotating when the boat turns under the influence of wind and weather. For water lubrication in particular, it is an advantage that this is done in the wet area, basically open to the sea. The invention will now be explained in more detail with reference to Figures 1 to 13, in which: Figure 1 is a section of a cross section through a tanker converted with the anchor and riser device, Figure 2 is a section through the axial and radial bearing of the rotary body, with a primary seal and a secondary seal, Figure 3 is a perspective section seen from the top of the axial and radial annular bearings, respectively in Figure 2 , Figure 4 is a sectional view from the top of the bearing in Figures 2 and 3, Figure 5 is an isometric view of the bearing segment according to the invention, Figure 6 is a section through the segment of the bearing in figure 5, figure 7 illustrates the front part of a converted tank-vessel, with an anchor table mounted below the ship, figure 8 illustrates the buoy anchor table, on a larger scale, Figure 9 illustrates the front part of a converted tanker, with a modified anchor table mounted below the ship, Figure 10 illustrates the anchor table in Figure 9lexion. , on a larger scale, figure 11 is a section through the vertical shot on a boat with the rotating body and the anchor table connected. Figures 12 and 13 are detailed sections respectively illustrating a possible immobilization of the rotating body and the anchoring table. In Figure 1, the rotating body 11 is shown positioned in a vertical shot 6 in the hull 1 of a ship. The shot 6 can be provided in a cassette 5 which is incorporated in the helmet 1 as described in the parallel patent application mentioned at the beginning. The body 11 has a lower side 12 and a side 13 above, and, as illustrated in Figure 1, is constructed as a cylindrical plate structure with an external cylinder 14 and a central stem 15 extending from the lower side 12 of the body 11 upwards, through the side 13 higher. In figure 1 two horizontal annular plates 16, 17 are illustrated which are welded between the central stem 15 and the external cylinder 14. The buttresses and other structural elements known to a person skilled in the art are not shown. Of course, the body 11 can be constructed in other ways which are well known to those skilled in the art. On its upper side 13, the body 11 has a flange 18, see also Fig. 2. This flange 18 is used for the rotational mounting of the body 11, as illustrated in Fig. 2. This will be described in greater detail in the following . In the annular space between the central stem 15 and the external cylinder 14, the body 11 has several liners 19, 20 which are provided for anchor changes 21 and riser tubes 22, respectively. The anchor cables 21 are tightened by means of a winch 23 on the deck 24 of the vessel. Several cable guides 25 are mounted on the cover (only one is illustrated in FIG. 1) which allows the mooring cables 21 to be operated by a single winch 23. The mooring cables 21 are suspended in a manner not shown in FIG. greater detail with the number 26 on the upper side 13 of the body 11, with the result that the mooring cables do not extend upwards in the shot after the anchoring is completed. The individual riser tubes 22 amount to the respective valve block 27 mounted on the upper part of the central stem 15. Each of the valve blocks 27 comprises an ESD (emergency disconnected) valve. On the central stem 15 a fluid manifold column 28 is mounted from which the fluid lines 29 extend to the tanks on board the vessel. Rounding out the central stem 15 is also provided with an operation platform 30. The space in the shot 6 above the upper side 13 of the body 11 is dry. The body 11 is distributed in the lower area of the tanker and is considered to be a wet area. Now we refer to Figure 2 and Figures 3 to 6 successive to explain the assembly of the body 11 in the shot 6. In the transition between the lower section 7 of the shot and the upper section 8 of the shot a packaging device is provided and bearing comprising a segmented annular axial bearing 31 and a radial annular segmented bearing 32. The axial bearing 31 has several bearing segments 33. The annular bearing 32 also includes bearing segments 34, in this case a smaller number (half) than the bearing segments 33 in the axial bearing.

Above the two annular bearings 31, 32 a dynamic primary seal 35 is mounted between the flange 18 of body 11 and a console 36. Above this dynamic primary seal a backup bearing 37 is mounted in order to prevent the rotating body 11 is lifted. This bearing 37 in the backrest forms part of several plate segments 38 which are screwed to the console 36 by several screws 39, see also figure 3. The plate elements 38 are provided with the connecting flanges 40 which can be joining by screwing with the connecting flanges on adjacent plate elements and in this way a surrounding platform cover is formed. A secondary seal 41 is mounted below the flange 18. This is designed to be activated only during the inspection / replacement of the bearing elements 33, 34. In addition, there is a seal 42. This is only for use if the secondary seal 41 needs to be replaced, in which case, therefore, it is only a question of mounting the seal. As mentioned in the foregoing, the two annular bearings 31, 32 are formed of bearing segments 33 and 34, respectively. These bearing segments are basically of identical design, therefore only the following will be described in detail in the following. construction of a bearing segment 33, with reference to FIGS. 5 and 6. As illustrated in FIGS. 5 and 6, the bearing segment 33 is constituted by a box 43 on which an upper wear part 44 is mounted, an intermediate part 45 and a lower part 46 of adjustable height consisting of two interacting wedge elements 47, 48. The wear part 44 is made of a suitable material which will be well known to a person skilled in the art and the intermediate part advantageously made of a reinforced rubber material which will provide some degree of resilience. The wedges 47, 48 can be moved relative to each other by means of adjustment elements 49 only delineated in FIG. 10. By altering the relative position of the wedge elements, the height of the bearing segment 33 can be adjusted. The bearing segment 33 is designed and provided with pressure lubrication, as indicated by the tube 50 from which the branch tubes 51 extend to cruciform grooves 52 in the wear portion 44. As already mentioned, lubrication with pressurized water can be used in a particularly advantageous manner. It should be mentioned at this point that the bearing segments can operate in various modes, depending of the operating conditions; passive without any kind of lubrication, a standard sliding bearing; a sliding bearing with the ability to inject grease; active pressure lubrication by injection of a medium, typically water, which provides separation of the surfaces, i.e., a hydrostatic bearing. The body 11 is also mounted on the bottom of the ship in a manner known per se. The lower radial bearing is not shown, but it is also in the form of a segmented annular bearing. In order to reduce the non-circularity of the body 11 to a minimum, it will be advantageous to mount a machined stainless steel ring at the bearing point. The steel ring will ensure a uniform and continuous load distribution around the circumference of the body 11. In order to protect the steel ring against corrosion a cathodic protective system is provided. A significant advantage is that there is access for inspection, adjustment and replacement of all bearings and their segments. In FIG. 1, mooring cables and ascending tubes are passed upwards through guides in the body 11 mounted rotatably. It is known that the rotating body 11, as a geostationary mounted body, will present the tendency to follow the rotation of the ship under the influence of the wind of the climate or when the boat turns under the influence of a DP system (of dynamic placement). This is due to the inertia in the assembly of the rotating body. One way to avoid this is to have a drive unit in the rotating body and therefore allow it to turn positively. Another way is to provide larger lever arms for the lashing cables when they are connected to the rotating body, that is, the lower annular bearing for the rotating body in the shot. Figure 11 illustrates a possible embodiment in which an anchor table 53 is mounted which is connected to the rotating body 11 at the bottom thereof. The anchoring table 53 has pick-up devices 54 which are provided with a larger diameter than the rotating body 11 with the result that, due to the fact that the cables are suspended in the pick-up accessories 54 on the table 53, the cables 21 of mooring acquire a larger lever arm in relation to the rotating body 11. In Figure 11, the vertical guides 55 are illustrated for the lifting means 56 for hoisting the anchoring table 53 towards the rotating part 11. Between the rotating part 11 and the anchoring table 53, a connection means 57 is provided, see FIGS. 12 and 13. The riser tubes 22 are connected to the anchoring table 53 and mounted on the rotary body 11. coupling ends 58 suitable for interaction with the risers 22 when they are hoisted together with the table 53. The anchor table can be connected to the rotating body in several possible ways: it can be welded against the rotating body in the gunner; it can be attached to the rotating body by means of a bolted connection, which allows everything to be easily dismantled; it can be pulled towards the rotating body in the field and can be connected to the rotating body manually from the ship or can be connected in a remotely controlled manner. The anchoring table 53 with associated risers 22 of anchored location submerged in the water when the ship 1 moves on it. The lifting means (cables) are attached to the anchoring table 53 and, by means of winches (not shown), the anchoring table 53 is hoisted and connected to the rotating body 11 by means of the couplings 57 which are attached to the anchor table 53. illustrated in Figures 12 and 13. A winch distribution equal or similar to that shown in Figure 1 can be used, for example. The couplings 57 contain hooks 59 rotatably mounted which, by means of the working cylinders 60, can be placed in engagement with cutouts within the anchoring table 53.

In order to keep the anchor table 53, submerged in the water, afloat, before the connection, the anchoring table 53 is attached to a buoy, as can be seen, for example, in figure 7 or 9. Fig. 7 a buoy 62 is provided on the upper side of the anchoring table 53. When the connection between the rotary body 11 and the anchor table 53 is to be carried out, a cable 63 (or several) is lowered from the ship, from a ship crane, not shown, to the buoy 62. elevation means 56 (not shown) is attached to the anchoring table 53, in this case it is connected to the cables 64. The buoy 62 is inflated, by a controlled release of air and the introduction of water to the buoy 62, then that the anchoring table 53 is attached to the lifting means 56, the buoy 62 can be neutralized and released from the anchoring table 53, suspended on the cable 63. The buoy 62 can then be moved laterally in a controlled manner and away of the water (not shown) whereby the anchoring table 53 can be hoisted by the lifting means 56 and can be connected to the rotating body 11, as shown in Figures 11-13. In figure 9, the buoy 65 is placed under the table 53 and accompanies the anchoring table 53 upwards, towards the rotary body 11 after the cables 56 are connected. In this case also, the floating capacity The buoy can be controlled with air and water, as is known to those skilled in the art. Here, the risers 22 are passed through the buoy 65. It will be apparent from FIGS. 7 and 9 that the anchor and riser distribution, as it is known, is distributed near the perpendicular front, where the moment of the beam of vessel 1 and the deformations are small, while retaining sufficient structural strength. The invention has now been explained with non-limiting modalities. A person skilled in the art will appreciate that a multiplicity of changes and modifications can be made with respect to the described embodiments which are within the scope of the invention as defined in the following claims.

Claims (10)

1. Anchoring device and geostationary riser tubes in a vessel comprising a body, which, in a wet boat area, is rotatably mounted about a vertical axis by means of radial and axial segmented annular bearings to the vessel, which body has a side upper and one lower side, guides for ascending tubes between the upper side and the lower side, which are provided with a superposed fluid manifold connected to the risers and which is anchored to the seabed by several mooring cables, characterized by a seal dynamic primary between the body and the boat, above the axial-radial bearing and by a secondary seal between the body and the boat, under the bearing. Anchoring device and geostationary ascending tubes as described in claim 1, characterized in that the mooring cables are connected to an anchoring table mounted under the body at points which have a diameter greater than the body. Anchoring device and geostationary ascending tubes as described in claim 2, characterized in that the anchor table is attached to a buoy, by which it allows it to float submerged in the water when it is not connected to the body. Anchoring device and geostationary ascending tubes as described in claims 1 to 3, characterized in that the multiple fluid column is supported by a central stem projecting from the upper side of the body. Anchoring device and geostationary ascending tubes as described in one of the preceding claims, characterized in that the central stem supports a surrounding operating platform above the upper side of the body. Anchoring device and geostationary ascending pipes as described in claim 5, characterized in that each rising pipe is connected to a block with an ESD valve (emergency disconnected) on one level with the operating platform. Anchoring device and geostationary ascending tubes as described in one of claims 1 to 6, characterized in that the body is constructed as a cylindrical plate structure with an upper side and a lower side with a central stem projecting from the lower side upwards, through the upper side and surrounding the stem, between the lower side and the upper side, coverings distributed for the ascending tubes, stem which is designed for support the fluid manifold. Anchoring device and geostationary ascending pipes as described in one of claims 1 to 7, characterized in that at least one of the segmented ring bearings comprises a bearing segment comprising a wear part against the body, wear part which can be lubricated under pressure, an intermediate part with a certain degree of resilience and a lower part adjustable in height against the boat. 9. Anchoring device and geostationary ascending tubes as described in claim 8, characterized in that the lower part comprises interaction wedges which can be moved relative to one another for height adjustment. Anchoring device and geostationary ascending pipes as described in claim 8 or 9, characterized in that the system is provided for pressurized feeding of a medium suitable for lubricating the bearing support segments.