JP2012526702A - 2-step CAM system - Google Patents

Abstract

A two-step CAM system is provided.
The present invention includes a ship, and an elongated mooring column having an upper end connected to a ship arm protruding from the ship bow and a lower end connected to the seabed by a tether line. The mooring system is characterized in that the arm is rotatable about a horizontal axis.

Description

  The present invention relates to an offshore system for mooring a marine vessel, a mooring column having a height, an upper end portion and a lower end portion, and a mooring column set to the vessel. A rotating mooring arm that connects the upper end of the mooring column to the ship so as to allow rotation about a horizontal axis of the ship, and an upper end connected to the lower end of the mooring column. A plurality of heavy chains, said heavy chains extending to the sea floor with a loose catenary curve, providing the restoring force required to maintain the vessel once connected, and the mooring column can be The system is self-floating and holds the chain weight at the bottom to keep the chain from flowing.

  Hydrocarbons can be transported by various types of offshore terminals from offshore pipelines, such as those leading to subsea wells, to offshore tankers. It is desirable to allow tankers to leave the terminal under severe environmental conditions such as where there is a large floating ice group in addition to storms, and because they are not subject to many of the severe environmental conditions. Many of the terminals are submerged deep below sea level. One type of offshore terminal that can be used under these conditions has a riser with a lower end that is loosely tethered to the seabed, such as by a group of catenary curve chains. . The chain holds the riser above the seabed but deep underwater and allows the riser to be easily raised to the ship. An improvement in such a system that facilitates the connection of the upper part of the riser to the ship and provides improved mooring at a minimum cost is one of considerable value.

  The system known from U.S. Pat. No. 4,645,467 describes an offshore structure of the type having a riser loosely tethered by a chain and can facilitate the mechanics of fixation. In a detachable riser, the riser can have a lower end that is lifted and weighted until most of its height extends from the sea, providing better tethering dynamics. The weight can have a clamp weight that hangs from the lower end of the riser.

  Another reissued patent No. 32,578 comprises a floating device and a chain for tethering the floating device, said chain being connected to a body rotatable about the vertical axis of an arm attached to the floating device. The mooring system is explained. The conduit extends through the body from the seabed towards the floating device. This patent includes a buoy where the arm is rigidly attached to the floating device and the body has its own buoyancy that is connected to the arm by a quick coupling coupling with releasable locking means Special focus is on improvements that can be made or detached from.

  The present invention describes the two-step lifting of the mooring column upon connection of the vessel by its mooring arm to the mooring column. This two-stage lifting upon connection has the advantage of minimizing both the size and rigidity of the hoisting equipment. In the unlikely event that this lifting is done entirely by hoisting equipment (winches, lines, sheaves, etc.), this equipment will have a significant negative impact on the geometry, physics and cost of the connected equipment. Shortening the initial lift with low tension hoisting equipment results in lower tension and stiffness due to the lifting line that keeps the components small and relaxes the initial connection. The structural connection according to the present invention is able to handle heavy loads and therefore the mooring arm hydraulic lifting system is designed to lift the CAM to its operating position anchored at its high tension.

U.S. Pat. No. 4,645,467 Reissued Patent No. 32,578

  It is an object of the present invention to provide an offshore system for mooring a vessel in which the lifting of heavy chains on the mooring column is realized by the use of only a rotating arm after the vessel is connected to the mooring column. .

  Accordingly, it is a further object of the present invention to provide a system of the type described above that is financially efficient and suitable for use at lower depths than the same system according to the prior art.

  According to the present invention, the offshore mooring system provides a mooring device in which the rotating arm and the arm that reaches and lifts the mooring column are relaxed and does not require the use of an expensive and large winch.

  Furthermore, in the form according to the invention, the arm is mounted such that it can be moved from an inboard position to its operating position protruding beyond the bow of the ship, so that during transport the components Prevents hanging from and partially damaged by the effects of green water.

  The novel features of the invention are set forth with particularity in the appended claims. The invention is best understood from the following description when read in conjunction with the accompanying drawings.

FIG. 1 a shows a detailed view of the mooring arm retracting mechanism. FIG. 1b shows a detailed view of the mooring arm retracting mechanism. FIG. 2 shows a three-dimensional view of one possible embodiment mooring arm retracting mechanism according to the present invention. FIG. 3 shows the system according to the invention in one step of the connection procedure. FIG. 4 shows the system according to the invention in one step of the connection procedure. FIG. 5 shows the system according to the invention in one step of the connection procedure. FIG. 6 shows the system according to the invention in one step of the connection procedure.

  1a and 1b show plan views of a system according to the invention. In accordance with the present invention, the mooring arm 1 is horizontally mounted on the ship 5 to the cart wheels / rails that allow it to be moved forward to its operating position protruding beyond the bow of the ship as shown in FIG. 1b. Installed. In FIG. 1a, arm 1 is stowed and does not protrude beyond the bow of the ship, preventing components from hanging from the bow during transport and being partially damaged by the effects of green water. .

  FIG. 2 shows a three-dimensional view of one possible embodiment of a mooring arm retracting mechanism according to the present invention. In the embodiment shown, rack and pinion drive systems 17, 18 for retracting and extending the arm 1 are used. The pinion system ranch teeth 17 are provided along the length of the arm 1 and the toothed sprocket 18 is provided in the box 3. The pinion is driven by a hydraulic or electric motor. The rack and pinion limits the acceleration of the arm 1 due to the dynamic movement of the ship. The arm is slid by the friction pad 2 located inside the box-type structure 3. Box 3 also functions as a rotation system that rotates arm 1 downward and upward about axis 16. The box 3 is hinged to the two supports 19 by a shaft (not shown).

  The arm 1 is rotated around the axis 16 under the action of the powerful hydraulic cylinder 4. When the upper position of the arm is reached, the mechanical fixing system is activated to release the hydraulic pressure in the cylinder 4. The cylinder 4 is provided with a mechanical safety device system when a failure occurs during operation.

  The piping of the retractable arm 1 is connected by a spool piece that can be retracted and extended sideways. When the arm is extended, the spool piece extends and is connected to the export line on the arm with a graylock.

  In order to operate the system, the ship 5 navigates to the vicinity of the mooring column 8 protruding above the water level, and the ship stops and maintains the holding position. FIG. 3 shows the ship 5 as it is moved forward through the ship's bow gate along the rail 6 on the deck until the arm 1 projects beyond the bow 15 by a predetermined distance. The export line on the arm is located inside the arm to avoid problems with the slide box system.

  FIG. 4 shows the first connection step, where the ship 5 is in contact with the mooring column 8. The mooring column 8 is a counterweight articulated mooring (CAM) with a slim structure riser column, the upper end of which protrudes above the water, and the lower end of the mooring column 8 is anchored to the sea floor by a catenary curve-shaped mooring chain 9. Fixed and floating vertically in the water. During operation, the first part of the system is the weather of the moored ship, in addition to the heave, pitch, sway, sway and roll movement of the ship 5 It is connected to the mooring column 8 by a mechanical connecting machine with an articulated joint that allows no vaning.

  Piping to both arm 1 and mooring column 8 to allow the transfer of natural gas (or other product) from the storage tank of the ship to the shore to the submarine pipeline or from the submarine pipeline into the ship A system 10 is provided.

  The pick-up line is lowered from the outer end of the mooring arm 1 for connection (by work boat) to the line 11 pre-mounted on the top of the CAM column. The mooring arm 1 is then articulated downward using a water hammer pump on the ship deck so that the outer end of the arm 1 is close to the top of the mooring column.

  FIG. 5 shows further steps when the pick-up line is drawn to lift the mooring column upper part 12 into contact with the mechanical coupler 7 and the mooring arm 1 and the mooring column 8 are connected to each other. By shortening the initial lift with low tension, the hoisting equipment 13 keeps the components small, resulting in low tension requirements for the lift line.

  This low tension requirement results in a much more flexible line that stretches easier and better, and reduces line snatch loading due to the initial lifting physics of the mooring column 8 which results in a relative motion match between the column 8 and the vessel 5. avoid. The current in-phase motion allows a low impact structural connection as the column 8 is lifted by the line towards the coupling machine 7.

  FIG. 6 shows the final step of the connection between the ship and the mooring column. In this embodiment, it is clearly shown that the mooring arm 1 is articulated at a high position (not only horizontally) and the ship is now moored safely on the mooring column 8. The structural connection is able to handle large loads, so the hydraulic lifting system on the mooring arm 1 is designed to lift the column to its operating position anchored at its high tension.

  This is the final step in which the mooring chain is lifted from the seabed to increase the tension in the lifting line. Thus, the heavy chain provides the restoring force required for the mooring column function.

  The mooring arm 1 and the mooring column 8 piping system 10 may be connected, and then the output may be transferred from (or into) the vessel 5.

  In order to separate the two parts of the mooring system after load transfer, the piping system is first flushed and then separated. The mooring arm is then rotated to its lower level, and then the mechanical coupler is released. The ship leaves from the mooring point.

  In the case of an emergency, the mooring column 8 and the pipe 10 can be quickly disconnected and released from the mooring position during operation.

  Furthermore, in order to cope with the collision, the pillar 8 needs to have a waterproof compartment as a whole along its length. The waterproof compartment is accessible by bolted flange access with a gasket between the flanges.

  A buffering system may be installed around the top of the column 8 to allow the support vessel to moor on the column and to facilitate personnel interference and maintenance.

  Many changes and modifications may be made to the practice of the invention without departing from its spirit or scope, as will be apparent to those skilled in the art in view of the foregoing disclosure. Accordingly, the scope of the invention should be construed according to the subject matter defined by the following claims.

Claims (7)

  A ship (5), an upper end (12) connected to the arm (1) of the ship (5) protruding from the ship bow (15), and a lower end connected to the seabed by a tether line (9) A mooring system comprising an elongate mooring column (10) having said mooring system, wherein said arm (1) is rotatable about a transverse axis (16).   The arm (1) is placed between the retracted position where at least most of the arm (1) extends into the ship and the mooring position where the arm (1) protrudes out of the ship (15) from the bow (15). The mooring system according to claim 1, further comprising a displacement member (2 and 3) for moving in the longitudinal direction of 5).   Mooring system according to claim 1 or 2, wherein the arm (1) is capable of rotating along an axis (16) in an upward direction relative to the horizontal.   Mooring system according to any of the preceding claims, wherein the arm (1) is displaceable in the longitudinal direction by a pinion system (17, 18). The mooring column is rotatable about a pair of horizontal axes with respect to the ship;
A plurality of chains have an upper end coupled to the lower end of the mooring post, the chains extending to the sea floor with a catenary curve, and once connected, to keep the ship moored The mooring column is free to attach to any buoyant body, the column is self-buoyant, holds the chain weight at the bottom, and the chain flows 5. A mooring system for mooring a vessel (5) according to claim 4, wherein the chain and the mooring column are lifted by using only the rotating arm after the connection with the mooring column of the vessel. A mooring system, characterized in that the rotation of the arm is capable of providing the required tension.   The rotating arm is also retracted so that it can be moved forward to its operating position protruding beyond the bow of the ship and backward so as not to protrude beyond the bow of the ship during transport. A mooring system for mooring a vessel as claimed in claim 2 which is possible. A method of mooring a ship to the sea, a ship (5), a mooring post (10) having a height and having an upper end (12) and a lower end, and the mooring post being the ship A rotating arm (1) for coupling the upper end of the mooring column to the ship to allow rotation about a pair of horizontal axes, and an upper coupled to the lower end of the mooring column The chain comprises a plurality of chains having ends, and the weight extends to the sea floor with a catenary curve and provides the restoring force needed to keep the vessel once connected moored. The lower half of the mooring column is free to attach to any buoyant body having a positive buoyancy greater than the negative buoyancy of the heavy chain;
-Navigating the ship to a point where the upper end of the mooring column projects above the water;
-Stopping the ship and maintaining the position;
-Moving the rotating arm along its length until the arm protrudes a predetermined distance beyond the bow;
-Lowering the pick-up line from the outer end of the mooring arm for connection to a messenger line pre-attached to the top of the elongated mooring post by a pull-in line;
-Articulating the rotating arm downward about an axis (16) using a water hammer pump on the ship deck so that the outer end of the arm approaches the top of the upper part of the elongated mooring post Steps,
-Pulling up a pick-up line so that the upper part of the mooring column is pulled up and brought into contact with a mechanical coupling machine until the rotating arm and the mooring column are connected to each other;
-After connection, the rotating arm is articulated to a level that provides tension to the mooring column and chain to moor the ship to the mooring column;
The arm and the buoy element piping system are connected, and the output is transferred from / to the ship by the piping system;

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