JPS61275086A - Rotary mooring device - Google Patents

Abstract

PURPOSE:To make it possible to carry out the guide of a rotating cylindrical section constituting a turret together with an upper rotary board, by disposing the turret rotatably in a well formed in the center section of a floating body, and by disposing plain bearings the cylindrical section of the turret and the well. CONSTITUTION:A turret 3 is supported rotatably in a well 2 formed piercing through in the center section of a floating body 1 for an off-shore working platform for digging petroleum and so forth, and a mooring cable 12 in a chain locker 20 is connected to an anchor through a winch 22 and rollers 21, 13, thereby a rotary mooring device may be constituted. The turret 3 is composed of a lower cylindrical section 4 and an upper rotary board section 5 which is supported by bearings 24, 25 while the cylindrical section 4 is supported to the well 2 of the floating body by means of the plain bearings disposed therebetween. Due to the provision of the plain bearings which may be held under water, the cylindrical section may be supported to the lower section of the floating body under water, thereby it is possible to smoothly guide the cylindrical section.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a rotary mooring device (also referred to as a turret device),
In particular, the present invention relates to a rotary mooring device suitable for mooring an offshore work platform with a large mooring force.

[Conventional technology]

Large floating structures called offshore platforms are used for oil exploration and production in offshore oil fields.

This offshore work platform is a large structure measuring between 3,000 mm and 5,000 mm, and is moored at a predetermined position to proceed with oil drilling and other operations under unfavorable sea conditions such as waves and strong wind and rain. Because of this necessity, large mooring devices with large mooring forces are used.

For example, US Pat. No. 3,279,404 has proposed a device for stably mooring this large offshore work platform at a predetermined position.

FIG. 5 is a schematic cross-sectional view showing the main parts of the rotary mooring device proposed in the above-mentioned U.S. patent. is,
Rotary mooring bag W covering the inside and upper part of this well 2
, R is rotatably provided.

This turret 3 is composed of a cylindrical part 4 and a rotary disk part 5 formed by expanding the upper part of this cylindrical part 4 in the shape of a flange in the horizontal direction, and between the upper surface of the floating body 1, the rotary disk part 5, and the lower surface. A bearing 6 provided to bear the vertical force and a floating body 1
A bearing 7 is provided on the upper part of the cylindrical part 4 and bears the lateral force by contacting the periphery of the cylindrical part 4, and a bearing 7 is provided on the lower surface of the arm 9 of the upper structure 8 to absorb the force that causes the rotary disc part 5 to rise. It is rotatably supported with respect to the floating body 1 by bearings 10 that bear the load.

The mooring line 12 untied from the winch 11 provided on the rotary disk portion 5 is guided by the roller 13 provided at the lower end of the cylindrical portion 4 through the outer periphery of the cylindrical portion 4, and further attached to the anchor sunk on the seabed. It is connected.

Past performance of rotary mooring equipment for oil drilling shows that the inner diameter M (also called moon pool) of turret 4 is 7~
It is about 8m. However, in the case of a rotary mooring device R used for an offshore work platform P for oil production, the turret 3
The diameter of the cylindrical part 4 and the rotary disc part 5 of the turret 3 is increased due to the need for oil production and processing equipment on the rotary disc part 5 at the top of the turret 3, and at the same time, the offshore work platform P is moored at a fixed position. As a result, the mooring force increases due to the need to withstand severe sea conditions.

Furthermore, when the floating body 1 is provided with an oil storage device, the structure of the rotary mooring device R becomes even larger, and the load acting on it also becomes a significantly larger value.

The rotary mooring device R having the above structure also has the following problems.

(1) A roller 13 is provided at the bottom of the cylindrical portion 4 to guide the mooring rope 12, and since the distance between the bearing 7 and the roller 13 is quite long, when the mooring force F acts on the mooring rope 12, the turret 3 At the same time, a large moment is generated that tends to bend the cylindrical portion 4 and the like.

(2) If the roller bearings are placed below the sea level W, there will be problems with maintenance and inspection, such as corrosion and adhesion of shellfish, so the bearings are concentrated in the upper part of the turret 3.

(3) As mentioned above, when the tension of the mooring rope 12 increases, a large bending moment is generated in the turret 3;
To counter this, it is necessary to increase the rigidity in order to prevent deformation of the turret 3, and it becomes necessary to make the entire rotary mooring bag-R larger than necessary, making it impossible to design it economically.

(4) The bearing 7 that supports the periphery of the cylindrical part 4 needs to bear the force acting on the cylindrical part 4 evenly, so the bearing 7 supports the periphery of the cylindrical part 4.
The bearings 7 are arranged closely because the gap between them cannot be made too large. As a result, there are problems such as making maintenance and inspection work difficult and requiring the turret 3 to have a strong structure that does not deform.

As mentioned above, conventional rotary mooring devices have various problems, and the turrets used for offshore oil production platforms have gradually become larger, which is why they have not been used in past oil production offshore platforms. Severe durability is required, which is different from rotary mooring devices.

[Purpose of the invention]

The present invention has been achieved in order to solve the problems of the conventional rotary mooring device for offshore work platforms, and its objects are (1) high durability;
To provide a rotary mooring device capable of generating a large mooring force.

(2) To provide a rotary mooring device that is easy to maintain and inspect.

(3) To provide a rotary mooring device in which the moment generated in the turret is minimized to prevent the turret from increasing in size and weight, and the supporting structure thereof is simplified.

[Summary of the invention]

The configuration of the present invention to achieve the above object includes a well formed in a floating body, a turret having a cylindrical part located in the well, and a rotary disk part located in the upper part of the floating body, and A rotary mooring device comprising a mooring cable extending between the floating body and the seabed, and a plain bearing is used as a bearing provided between at least the cylindrical part and the surface of the well. It is.

The basic technical idea of the rotary mooring device according to the present invention is as follows.

(1) Most of the conventionally used roller bearings will be abolished, and a plain bearing structure will be adopted that can withstand large loads, is resistant to wear, and requires no maintenance or inspection.

(2) To provide a structure that can be installed even under sea level, reduces the moment acting on the turret as much as possible, reduces the weight of the turret structure, and can accommodate large-diameter turrets.

〔Example〕

Next, embodiments of the rotary mooring device according to the present invention will be described with reference to the drawings.

Fig. 1 is a sectional view showing the main parts of a device using the present invention as a rotary mooring device for a marine work platform, Fig. 2 is a sectional view taken along the line -■ in Fig. 1, and Fig. 3 is a sectional view taken along -■ in Fig. 1. −■ It is a sectional view.

A turret 3 is rotatably supported in a well 2 provided on the floating body 1, and a chenolocker 2 provided on the floating body 1
The mooring line 12 housed in the mooring cable 12 is connected to the anchor via a winch 22, rollers 21, and rollers 13.

Now, the supporting structure of the turret of the rotary mooring device according to the present invention is characterized by the use of plain bearings.
These bearings are used for bearings 23 that bear the lateral force, bearings 24 that support the lower surface of the rotary disk section 5, and bearings 25 that support the side surfaces of the rotary disk section 5.

This plain bearing needs to be used in locations where maintenance and inspection are easy, and it is particularly effective to use it for the bearing 23.

In addition, as shown in FIGS. 2 and 3, the bearings 23 and 24 are arranged to face each other at the bow side B and the stern side S, and the bearings 23 and 24 located at other positions are also arranged to face each other through the center of the well 2. It's good to do that.

In the present invention, it is necessary to use at least a plain bearing for the bearing 23, and as an example of the structure, the one shown in FIG. 4 can be used.

A wear-resistant material 31 is supported on the cylindrical portion 4 side of the turret 3 by a base 30. The wear-resistant material 31 is a wear-resistant material, such as a stainless steel plate.

Further, on the side of the well 2 formed in the floating body 1, a base 34 is placed on a support stand 32 via a spring material 33, and fixed with fastening members such as bolts 35 and nuts 36. Further, a wear-resistant material 38 is supported on the base 34 via a cushion material 37. As the wear-resistant material 38, a wear-resistant material with a small coefficient of friction and corrosion resistance is selected.

The wear-resistant material 38 constituting the plain bearing includes, for example,
We use materials with high corrosion resistance and pressure resistance, such as Zintert carbon, which is produced by molding 100% carbon material (powder) and treating it at high temperatures, copper alloy, ceramic, and industrial resins such as Teflon and nylon. do.

The wear-resistant material 38 normally withstands long-term use, but in order to inspect it and replace it in some cases, the wear-resistant material 38 is
It can be constructed such that it can be pulled up and loaded again by an operation from above.

Further, as shown in FIG. 1, an opening 40 may be provided in the wall of the well 2 so that the bearing 23 and the like can be inspected by entering and exiting through the opening 40.

〔Effect of the invention〕

A rotary mooring device according to the present invention includes a well formed in a floating body, a turret having a cylindrical part located in the well, and a rotary disk part located in an upper part of the floating body, and It has a mooring line extending between the top and the seabed, and is characterized by using a plain bearing for at least the bearing provided between the cylindrical part and the surface of the well. It can be effective.

<1) In order to use a plain bearing, the bearing can be located at the sea surface W.

Therefore, even if a large mooring force acts on the turret 3, no large moment is generated on it.

Therefore, a highly durable rotary mooring device can be obtained.

(2) Because it uses plain bearings, there are no rotating parts, so it can be used well even in water where shellfish are attached. (3) The plain bearings are made of self-lubricating and wear-resistant material. By using it, maintenance and inspection become extremely easy.

(4) Since the moment can be made as small as possible as described above, it is possible to prevent the turret from increasing in size and weight.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the main parts of a offshore work platform equipped with a rotary mooring device according to the present invention, and FIG.
n cross-sectional view, Figure 3 is the ■-■ cross-sectional view in Figure 1, and Figure 4 is
The figure is a cross-sectional view showing an example of a plain bearing provided on a turret, and FIG. 5 is a schematic cross-sectional view showing a conventional rotary mooring device. 1... Floating body, 2... Well, 3... Turret, 4
... Cylindrical part, 5... Rotating disk part, 23.24.25.
...Plain bearing, 30...Base, 31...
・Abrasion resistant material, 32... Support stand, 33... Spring material, 34... Base, 37... Cushion material, 3 days.
・・Wear-resistant material.

Claims (1)

[Claims] A turret having a well formed in a floating body, a cylindrical part located in the well, and a rotary disk part located on the upper part of the floating body, and a turret extending between the top of the floating body and the seabed via the turret. 1. A rotary mooring device comprising a mooring cable, and a plain bearing is used as a bearing provided between at least the cylindrical portion and the surface of the well.