JPH033830B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a construction method for laying an underwater intake pipe in, for example, ocean temperature difference power generation.

[Prior art] Ocean thermal power generation uses ocean surface warm water (24 to 28 degrees Celsius) heated by solar energy and deep water (100 to 28 degrees Celsius) that circulates from the polar regions in the ocean general circulation.
1000m) and cold water (4-7℃)
℃) to operate a heat engine and obtain useful energy such as electrical energy.

The methods can be roughly divided into closed cycle methods and open cycle methods. An example of a closed cycle system is shown in FIG.

In the figure, a is a cold water intake pipe, b is a cold water pump, c is a condenser, d is a hot water intake pipe, e is a hot water pump, f is an evaporator, g is a working fluid pump, h is a turbine, and i is a generator. This method transfers heat from seawater to a low-boiling point medium such as ammonia, fluorocarbon-based media, or propane to increase energy density and generate electricity.In the case of a closed cycle method, the working fluid undergoes evaporation, expansion, and condensation. Repeatedly, constantly cycling in a closed loop.

By the way, one of the important technologies in such ocean temperature difference power generation is the installation of cold water intake pipes for taking cold water from deep layers (100 to 1000 m).

Generally, the submarine towing method, floating towing method, and laying ship method are known as methods for laying submarine pipelines.

The submarine towing method requires space and equipment for manufacturing and towing long pipes in the pipe yard, and also requires launching equipment. It also requires large towing equipment.
Furthermore, to adjust the weight of the tube, a buoy is required to reduce the underwater weight of the tube in order to reduce the frictional force with the seabed and reduce the towing force.

The floating towing method does not require the pipe yard to be an extension of the pipeline, but it does require space and equipment to manufacture long pipes and launch the tow. In addition, the equipment used requires a large number of ships. Furthermore, in order to adjust the weight of the tube, it is necessary to reduce the weight of the tube underwater so that the tube can bend smoothly from the sea surface to the seabed. Other environmental conditions include relatively calm weather.

The laying ship method does not require a land yard other than a steel pipe storage yard as a pipe yard, but it does require a specially equipped laying ship as equipment. In addition, it is necessary to adjust the weight of the pipe so that the steel pipe can be installed smoothly from the installation ship to the seabed.
Furthermore, relatively calm weather is required as an environmental condition.

Of the submarine towing method, floating towing method, and towing boat method, the methods that can be implemented for laying cold water intake pipes in ocean temperature difference power generation are the submarine towing method and floating towing method, but these methods include the above-mentioned methods. There was a problem.

[Problems to be Solved by the Invention] The present invention solves the above-mentioned problems of the submarine towing method, floating towing method, and laying ship construction method that have been adopted as conventional methods for laying submarine pipelines. There is no need for a land yard, it is almost unaffected by environmental conditions, the equipment used only requires the modification and rigging of ordinary barges, it does not require too many ships, and it is easy to use pipes. This method was developed to provide a construction method for installing underwater intake pipes in temperature difference power generation, which does not require weight adjustment, is suitable for deep-sea piping, and allows installation of large-diameter pipes.

[Means for Solving the Problems] The construction method for laying a bottom water intake pipe according to the present invention maintains the work boat offshore at a depth greater than the installation water depth of the cold water intake, and installs a chain anchor and a hanging wire attached to the water intake and the water intake. Set up on a work boat, connect the single pipes, install support frames at specified intervals around the outer circumference of the single pipes, extend the suspension wire vertically, connect the single pipes at the specified water depth of the water intake part, and connect them to land. Move the work boat toward the bottom and place the chain anchor and intake section on the bottom.
We checked the bottoming status of the water intake, connected the single pipe, extended the suspension wire, and at the same time moved the work boat to land.
Lay the intake pipes one by one at the bottom of the water, and as you approach the shore,
From the land side, use a landing wire to lift the suspension wire from the work boat to the shore, and after the intake pipe has landed on the slope, it is fixed to the anchor, and the remaining piping on the slope is done, and the cold water reservoir is installed. (power plant).

[Example] 1 Construction specifications 1.1 Cold water intake water intake volume: ^70m3 /min Intake pipe: inner diameter 1000mm (flow velocity = 1.50m/min)
sec) Extension: Slope 900m (from leaf line to water intake) Horizontal 180m (from leaf line to plant) Intake depth: RL-600m 1.2 Hot water intake water intake: 100m ³ /min Intake channel: width 2m Effective water depth Channel length of 1 m or more Length: 180 m (from reef line to plant) Intake depth: Intake of surface water (1 m or more above the lowest water level) 2 Consideration of cold water intake pipes 2.1 Pipe materials Materials for submarine piping include steel pipes, FRP pipes, and rigid pipes. There are PVC pipes and hard polyethylene pipes, but their prerequisite is good insulation. Durable. Strong impact resistance. We have a track record of producing large diameter pipes. Considering these factors, FRP pipes will be adopted for practical plants.

2.2 Joint method A single pipe length (length of one pipe) of 10 m is used, and the pipes are joined using a joint. The flange method will be adopted as the joint method from the viewpoint of ease of construction and reliability.

Regarding the installation of water intake pipes based on the above construction use,
This will be explained below with reference to the drawings.

Suspend the intake pipe to a water depth of 600m, move the work boat towards land while joining the single pipes, and lay the intake pipe. The details of the procedure will be explained below.

Figure 2 shows the plan layout of the work boat.
The position will be maintained offshore at a depth of 600 m or more using two locations each, Bit 2 on land A, Anchor 3 on the seabed B, and a tugboat 4 (one boat) on the sea side. A winch 5, a crawler crane 6, etc. are provided on the work boat 1.

Figure 3 shows the cross-sectional layout of the work boat, and shows the water intake section 8.
and chain anchor 11 and three hanging wires 1
2 on the work boat 1, and the length is 10 m, for example.
A single pipe 9 made of FRP is connected, a support frame 13 is attached every 5 m, a hanging wire 12 is extended vertically, and the single pipe 9 is connected at a predetermined water depth for taking water.

A cross-sectional view of the entire structure is shown in FIG. 4. The mooring wire 2a (FIG. 2) of the onshore bit 2 is wound up, the work boat 1 is moved toward land A, and the chain anchor 11 and water intake section 8 are brought to the bottom. let

Using a remote-controlled underwater television 15 such as an ROV, the status of the water intake section 8 reaching the bottom is confirmed. If it doesn't work, re-lay it. After that, the installation status of the water intake pipe 7 will also be confirmed.

The single pipe 9 is connected and the suspension wire 12 is extended, and at the same time the work boat 1 is moved to land A, and the intake pipes 7 are successively laid on the seabed B.

At approximately l=30m from the reef line A-1, from the land A side using the landing gear wire 16,
Pull the suspension wire 12 from the work boat 1 to land,
After the water intake pipe 7 is gradually brought to the bottom, it is fixed to an anchor in a buried trench that has been excavated in advance.

The remaining piping on the seabed B is carried out by the upper crane 6 of the work boat 1.
The single pipe 9 is suspended to the seabed B by using the same, and the single pipe 9 is connected by a diver in a buried trench that has been excavated in advance.

A vent pipe 9a is installed near the leaf line A-1 as shown in FIG. After that, piping will be installed from the land temporary road D shown in Figures 5 and 6 to the cold water reservoir C using a crane and a diver. Further, a flexible joint 10 (FIG. 7) is used as necessary.

Figure 8 shows the details of the cold water intake section.
The steel water intake part 8 and the single pipe 9 are connected by a flange joint 7a (FIG. 9). A rotatable hexagonal support frame 13 is attached to the water intake part 8, and a hanging wire 12 is set therein. Further, a rotatable octagonal support pedestal 14 is attached to the open end, and a chain anchor 11 is set therein.

FIG. 9 shows details of the support frame for the water intake pipe, and a hexagonal support frame 13 is attached to the outer periphery of the water intake pipe 7 at the connecting portion 7a of the single pipe 9 when viewed from the front. Assuming that the length of a single tube is 10 m, a support mount 13 is installed every 5 m. Further, the support frame 13 is provided with three clip members 13a for setting the three hanging wires 12.

[Effects of the invention] According to the construction method for cold water intake pipes according to the present invention,
The following excellent effects can be obtained.

(1) Land-based launching equipment associated with pipe extraction is not required.

(2) Applicable to any pipe fitting method.

(3) Since the installation begins in a vertical connection offshore where waves are relatively calm, there are few areas affected by waves, making it safe and requiring a short construction period.

(4) By fixing the suspension wire, the intake pipe can be safely installed on the slope of the seabed, not only when the slope of the seabed is gentle, but also when it is steep.

(5) There are fewer work fleets compared to the floating towing method.

(6) Buoys required for weight balance in the submarine towing method are not required.

(7) Since they can be installed sequentially on the seabed starting from the water intake, the water depth at the water intake can be determined.

(8) Can also be used for laying large diameter pipes.

(9) It can also be applied to the construction of water intake pipes for offshore plants.

[Brief explanation of the drawing]

Figure 1 shows the principle of ocean temperature difference power generation, Figure 2
Figure 3 is a plan layout of the work boat, Figure 3 is a sectional layout of the work boat, Figure 4 is an overall sectional view, Figure 5 is a detailed sectional view of the reservoir, Figure 6 is a detailed sectional view of the land area, 7
8 is a detailed side view and a plan view of the cold water intake section, and FIG. 9 is a detailed vertical sectional view and plan view of the support frame for the water intake pipe. 1...Work boat, 2...Bits, 3...Anchor,
4...Tugboat, 5...Winch, 6...Crawler crane, 7...Water intake pipe, 8...Water intake section, 9...
Single pipe, 10...Flexible joint, 11...Chain anchor, 12...Hanging wire, 13...Intake pipe support mount, 14...Intake support mount, 15...Remotely controlled underwater television, 16...Land Metsusenja wire for lifting.

Claims (1)

[Claims] 1. Hold the work boat offshore at a water depth greater than the installation water depth of the cold water intake section, set the water intake section and the chain anchor and suspension wire to be attached to the water intake section on the work boat, connect the single pipes, and place them on the outer circumference of the single pipes as specified. Attach supporting frames at intervals of Check the status of the intake pipe on the bottom, connect the single pipe, and extend the suspension wire. At the same time, move the work boat to land and lay the intake pipes one by one on the bottom of the water. When approaching the shore, connect the pipe from the land side to the shore. After lifting the lifting wire from the work boat to shore using a lifting wire and letting the intake pipe reach the bottom of the slope, fix it to the anchor, perform the remaining piping on the slope, and then connect it to land. A construction method for installing underwater water intake pipes.