JP2003284940A - Method for generating gas hydrate in sea, gas hydrate generator, and underwater storage system of carbon dioxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly practically useful technology which can generate a large amount of CO<SB>2</SB>hydrate with a simple constitution and store it in the sea for isolating carbon dioxide causing global warming, in the ocean. <P>SOLUTION: In an underwater storage system of carbon dioxide, carbon dioxide is introduced into a gas hydrate generator 11 installed at a prescribed depth in the sea, carbon dioxide is brought into contact with seawater while regulating the water depth position of the gas hydrate generator 11 by buoyancy due to gas or the like stored in the generator, CO<SB>2</SB>hydrate 50 is generated by using seawater pressure, and the generated CO<SB>2</SB>hydrate 50 is settled and stored in storage parts 81, 82 on the bottom of sea. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing underwater gas hydrate, an underwater gas hydrate producing apparatus, and carbon dioxide, which can be used, for example, for the purpose of hydrating carbon dioxide gas (carbon dioxide gas) and storing it in the sea. Subsea storage system.

[0002]

2. Description of the Related Art With the progress of global warming due to carbon dioxide, it is planned to develop a technology for isolating carbon dioxide in the atmosphere by fixing it in the ocean.
l.80 No.896, p1156-1164 (2001. 12 May); "high pressure science and technology", Vol. 11 (2001) 42nd special issue high-pressure debate Abstracts p34-35, and CO ₂ ocean sequestration CO ₂ hydrate (Takeo Aya)]. Ocean sequestration of carbon dioxide can be roughly divided into "dissolution method" and "storage method". As a storage method, a liquid CO ₂ storage method, a hydrate storage method, and the like have been proposed. As a typical example of the liquid CO ₂ storage method, carbon dioxide is transferred to a CO ₂ storage sea area by a ship and the water depth is 3500 m. A method of sending liquid carbon dioxide through a pipe to a deeper ocean floor is being studied. The hydrate storage method is a method in which carbon dioxide is stored in the seabed as an inclusion compound called clathrate hydrate (simply referred to as “hydrate” in the present invention).

By the way, when producing CO ₂ hydrate on land, it is necessary to use carbon dioxide and water as raw materials, pressurize the inside of the reactor to a pressure of 1 MPa or more, and cool the temperature to near 0 ° C. , High pressure equipment and cooling equipment are required. For the purpose of mitigating global warming, it is necessary to sequester a large amount of carbon dioxide, but in order to produce a large amount of CO ₂ hydrate, a large-scale high-pressure / cooling facility is required, and carbon dioxide is consumed on land. It is not realistic to switch from hydrate to hydrate.

As a technique for producing a hydrate in the sea, a method for immobilizing carbon dioxide gas in the deep sea has been proposed in Japanese Patent Laid-Open No. 5-4039. This method
Carbon dioxide and seawater are pumped into a transport pipe that extends to the deep sea, and C
In addition to generating O ₂ hydrate, methane hydrate existing in the deep sea is sampled, and heat of formation of CO ₂ hydrate and heat of decomposition of methane hydrate are heat-exchanged. However, since this method is a method for producing hydrate in the transport pipe, there is a concern that clogging may occur due to the production of massive hydrate. Further, since it is necessary to extend the double pipe to the deep sea of 500 m to 600 m or more, the device becomes large-scaled and the feasibility is poor. Furthermore, there is a large restriction on the installation site in that carbon dioxide must be transported to a point containing methane hydrate (not necessarily near the sea).

[0005]

SUMMARY OF THE INVENTION The first object of the present invention is to provide a method for efficiently producing a large amount of gas hydrate in the sea and an apparatus suitable for the method, and thus to provide the earth. It is a second object to provide a highly practical system that generates a large amount of CO ₂ hydrate with a simple structure and stores it in the sea in order to sequester carbon dioxide that causes global warming in the sea. .

[0006]

In order to solve the above-mentioned problems, the invention of the method for producing a gas hydrate in the sea according to claim 1 provides a gas hydrate-forming substance in a generator provided in the sea at a predetermined water depth. The method is characterized in that the water depth position of the generator is adjusted by the buoyancy of the generator, the gas hydrate-forming substance is brought into contact with seawater, and the gas hydrate is generated using seawater pressure.

According to the invention of the method for producing gas hydrate in the sea, since the gas hydrate is produced by utilizing the water pressure in the sea, a high pressure facility as in the case of producing gas hydrate on land is unnecessary. And since the water depth position of the generator can be adjusted by the buoyancy of the generator,
It is possible to easily maintain a desired water depth position, and it is possible to maintain an optimum gas hydrate generation environment.

Further, the invention of the undersea storage system of carbon dioxide according to claim 2 is the method for producing underwater gas hydrate according to claim 1, wherein the carbon dioxide introduced from land is hydrated in the sea. The produced CO ₂ hydrate is allowed to settle and stored in a storage section on the seabed.

The method of hydrating carbon dioxide and sequestering it in the sea is a method of dissolving carbon dioxide and storing it in the sea (so-called dissolution method), which is a local increase in dissolved carbon dioxide concentration or diffusion into the sea. Since there is no possibility of adversely affecting the seawater environment, such realization is desired. In the invention of the undersea storage system of carbon dioxide of the present invention, the gas hydrate is generated by utilizing the seawater pressure and the seawater temperature, and the water depth position is controlled by utilizing the buoyancy of the generator, so that the energy consumption is kept low. It is possible and the device used is simple. Therefore,
The undersea storage system of the present invention is a system suitable for storing a large amount of carbon dioxide in the atmosphere, which causes global warming, in the sea.

The invention of a submerged gas hydrate generator according to a third aspect is arranged in the sea, and the gas hydrate is generated by utilizing seawater pressure by bringing the gas hydrate-forming substance into contact with seawater. An underwater gas hydrate production device, characterized in that it is provided with a gas storage part for storing gas, and that the buoyancy of the device is utilized to control the water depth position.

According to the invention of the underwater gas hydrate generator, since the water depth position can be adjusted by the buoyancy of the device, it is possible to easily maintain a desired water depth position suitable for gas hydrate generation. In order to generate a gas hydrate by utilizing the water pressure in the sea, it is necessary to control the water depth position of the generator so that the water pressure satisfies the hydrate generation condition. If this water depth position is controlled by a fixture, it is necessary to lay the equipment up to a depth of 100 m or more in the sea, and it is also necessary to have strength to cope with changes in ocean currents and tide levels. Will be required. On the other hand, in the present invention, since the position adjustment can be performed by utilizing the buoyancy of the raw material gas or the like stored in the generator, fine adjustment is easy, and a simple device configuration always provides an optimal hydrate generation environment. Can be maintained. In addition, when installing the device, it is possible to adjust the buoyancy from the sea surface and gradually lower it, and also when performing the maintenance of the device, etc., it is possible to adjust the buoyancy and raise it to the sea surface. No need to use a large winch for installation or maintenance. Therefore, the gas hydrate generator of the present invention can be advantageously used, for example, in the storage of carbon dioxide in the sea.

The invention of a gas hydrate generator according to a fourth aspect is characterized in that, in the third aspect, it is connected to a flexible supply means for introducing the gas hydrate-forming substance. According to this feature, since the gas hydrate-forming substance is introduced from the land or the like by being connected to the flexible supply means, the flexible supply means enables the gas hydrate generation device in water. The position of can be set flexibly. That is, it is much easier to move the generator in the horizontal direction and adjust the water depth position as compared with metal pipes and the like.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an overview of a carbon dioxide subsea storage system according to an embodiment of the present invention. In the undersea storage system of the present embodiment, seawater pressure is used as the pressure required to generate the CO ₂ hydrate 50, and therefore a high-pressure reaction vessel is not required unlike the on-shore production.

[0014] That is, underwater storage system of the present invention, the CO ₂ hydrate 50 and mass production under mild conditions by utilizing the sea water pressure, resulting CO ₂ hydrate 5
0 can be stored and isolated on the seabed 200. CO ₂
Hydrate 50 has a seawater temperature of 10 ° C or lower,
Since it can be manufactured at a water depth of 100 to several hundreds of meters, it is possible to install the gas hydrate generation device 11 in the sea 100 in the sea area relatively close to the land, and mass production can be easily performed.

The gas hydrate generator 11 has a water depth of 1
It will be installed in the sea 100 of 100 to several hundred meters. The installation method is
You can choose from mooring method from the sea surface 300, mooring method from the seabed 200, installation method by installing a pedestal from the seabed 200, and method of self-sustaining underwater 100 by adjusting buoyancy and position control by propulsion machine without mooring. And is not particularly limited.

Supply of the gas hydrate-forming substance to the gas hydrate generator 11 arranged in the sea 100
As shown in FIG. 1, it can be performed from a supply device 61 installed on land via a flexible tube 60 as a supply means of a gas hydrate forming substance. As the flexible tube 60, for example, a tube in which a flexible material such as synthetic resin is reinforced with a steel wire can be used. Supply device 6
1 is equipped with a pressure-feeding means such as a compressor so that the gas hydrate-forming substance can be pressure-fed against the seawater pressure. Although not shown here, a power transmission pipe for supplying electric power to the gas hydrate generation device 11 also has a flexible structure and is arranged in parallel with the flexible tube 60.

The gas hydrate forming substance supplied to the gas hydrate generator 11 may be a gas (for example, carbon dioxide gas) or a liquid (liquid carbon dioxide). Liquefaction of a large amount of carbon dioxide for the purpose of sequestering carbon dioxide in the atmosphere into the sea requires a large amount of energy and equipment separately, but in the undersea storage system of the present invention, it remains as a gas as a gas hydrate forming substance. There are advantages that can be used.

In terms of the efficiency of hydrate formation, the gas hydrate-forming substance is preferably of a purity close to 100% in either case of gas or liquid, but in the present invention, the gas hydrate-forming device will be described later. Due to the characteristic structure of 11, even if oxygen, nitrogen or the like is mixed in carbon dioxide, it can be directly used as a gas hydrate-forming substance. Therefore, the equipment for the preliminary purification of the gas hydrate-forming substance can be simplified, and the energy consumption and the processing cost can be reduced.

The temperature inside the gas hydrate generator 11 does not require cooling if the temperature of the installation sea area is 10 ° C. or lower, but a cooling device may be provided to increase the generation rate. As the cooling device, for example, as described later,
Gas hydrate generator with jacket-type cooling device 1
The method of arranging around 1 is mentioned.

The CO ₂ hydrate 50 produced in the gas hydrate producing device 11 has a specific gravity larger than that of seawater, and therefore naturally precipitates and is stored in the storage portion on the seabed. Since CO ₂ hydrate stabilizes on the seabed, the environmental impact on the surrounding area is relatively small, and if an increase in the amount of dissolved carbon dioxide occurs, CO ₂ hydrate 5
It is also possible to collect 0 and move to another place. FIG. 1 shows a primary storage part 81 that stores the CO ₂ hydrate 50 that has settled, and a secondary storage part 82 that is provided on the seabed with a deeper water depth. Primary storage part 81, secondary storage part 8
In both cases, it is possible to use the natural seabed topography, but it is also possible to carry out construction such as excavation as necessary. The CO ₂ hydrate 50 can be transferred from the primary storage part 81 to the secondary storage part 82 by any method, but in the undersea storage system according to the present embodiment, the CO ₂ hydrate 50 is transferred together with the water flow as the transfer means. A jet pump 83 for sending the _2- hydrate 50 is provided.

Next, the structure of the gas hydrate generator 11 will be described in detail. FIG. 2 shows a schematic configuration of the gas hydrate generator 11 according to one embodiment of the present invention. The gas hydrate generation device 11 has an outer contour formed by a cylindrical body 31 made of a corrosion-resistant metal material (for example, stainless steel). The gas hydrate generator 11 does not have to have a pressure resistant structure. The lower part of the tubular body 31 is opened by an opening 35 that functions as a gas hydrate discharge part, and the upper part has a structure closed so that gas can be stored inside.

The upper part of the internal space of the gas hydrate generator 11 constitutes a gas storage part 33 for storing gas. The water depth position can be controlled by utilizing the buoyancy of the gas stored in the gas storage portion 33.

A valve mechanism 39 is provided above the gas hydrate generator 11 to connect the gas reservoir 33 to the outside of the apparatus. This valve mechanism 39 is
It has a function of discharging excess gas in the gas storage portion 33 and a buoyancy control function by adjusting the amount of gas storage.

Gas hydrate generator 1 having a cylindrical outer shape
A stirring shaft 46 and a stirring blade 47 (three pairs in FIG. 2) are provided at the center of No. 1 in order to enhance the gas hydrate generation efficiency. The stirring shaft 46 is rotated by the power of a motor 45 attached to the upper part of the apparatus, and the gas hydrate generator 1
The seawater in 1 and the gas hydrate forming substance can be mixed.

In the present embodiment, the flexible tube 60 constituting the gas hydrate-forming substance supply means has three branched ends (60a, 60b, 60c),
The gas hydrate generator 11 is connected to the introduction parts 37a, 37b, 37c provided at arbitrary positions. The positions of the introduction parts 37a to 37c are concentrated on one side of the lower side surface of the gas hydrate generation device 11 in FIG. 2, but the position is not limited to this, and the introduction can be performed from any position, and the number of introduction parts is also set arbitrarily. it can. In addition, the introduction parts 37a, 37
The inner surfaces of b and 37c and their vicinity are lined with fluororesin such as Teflon (registered trademark) or silicone. This is to prevent the gas hydrate-forming substance such as carbon dioxide gas introduced from the introduction part 37 from becoming hydrated and growing into a massive hydrate at this portion to cause a problem of blockage.

The position of the interface between the gas reservoir 33 and the seawater surface 53 inside the gas hydrate generator 11 must be controlled to be constant, and the gas hydrate generator 11 must be controlled in order to perform this control. An interface level meter 42 is provided. In addition, the gas hydrate generator 11
Is equipped with a water pressure sensor 41 for detecting the water depth position in the sea 100. In FIG. 1, reference numerals 43a and 43
Reference numeral b is a propulsion device for moving the gas hydrate generation device 11 in the horizontal direction and correcting the inclination due to the water flow.

Based on the above configuration, the underwater production of the CO ₂ hydrate 50 by the gas hydrate generator 11 of the present invention will be described. As shown in FIG. 2, the surrounding seawater flows into the inside of the gas hydrate generation device 11 from the seawater inlet appropriately arranged at the lower part and / or the side surface, and the gas liquid part 33 and the gas storage part 33 are surrounded. Forming an interface. The sea level 53, which is the gas-liquid sea level, is maintained at a predetermined level.

Carbon dioxide gas as a gas hydrate forming substance is introduced into the gas hydrate generator 11 from the supply device 61 installed on land through the flexible tube 60. In the gas hydrate generator 11,
The introduced carbon dioxide gas is brought into contact with seawater, and CO ₂ hydrate is produced by utilizing the seawater pressure. Here, by rotating the stirring blade 47, the contact efficiency of carbon dioxide gas and seawater is improved, and the hydrate generation efficiency is increased. The carbon dioxide gas introduced into the gas hydrate generator 11 gradually forms hydrate in the process of forming bubbles 51 and rising in the seawater. Of the introduced carbon dioxide gas, the remaining carbon dioxide gas that has not been hydrated and gas components such as oxygen and nitrogen contained as impurities in the raw material gas that are difficult to hydrate reach the gas storage section 33. Stored.

In the above gas hydrate production reaction, it is important that the water pressure and the water temperature at the place where the gas hydrate production apparatus 11 is installed match the gas hydrate production conditions. In the present invention, by adjusting the water depth position of the gas hydrate generation device 11 by the buoyancy of the gas stored in the gas storage portion 33 in the device, the gas hydrate is generated under the condition where the seawater pressure is optimum. be able to. The buoyancy depends on the amount of gas stored in the gas storage section 33. Therefore, the interface level meter 42 detects the level of the sea level 53 and monitors the amount of gas in the gas reservoir 33 to be constant.

The control of the amount of gas in the gas reservoir 33 can be easily realized by the valve mechanism 39 above the gas hydrate generator 11. By this valve mechanism 39, excess gas in the gas storage portion 33 is discharged, and the buoyancy can be controlled by adjusting the gas storage amount. When the source gas contains gas components such as oxygen and nitrogen that are difficult to hydrate, these are stored in the gas storage unit 3
Since it accumulates in No. 3, it is periodically discharged by the valve mechanism 39. Further, the water pressure sensor 41 can always detect the water depth position of the gas hydrate generator 11 in the sea 100 and can monitor whether or not a predetermined water pressure is maintained. Gas hydrate generator 11
Of the propulsion devices 43a, 43b
Can be adjusted by

With the above configuration, the underwater gas hydrate production apparatus 11 of the present invention does not require any high-pressure equipment as in the case of producing gas hydrate on land. Then, by the method of adjusting the water depth position of the gas hydrate generation device 11 by the buoyancy of the gas stored in the generation device, it becomes possible to easily maintain the desired water depth position, and always achieve optimum hydrate generation. The environment can be maintained.

The CO ₂ hydrate generated in the gas hydrate generator 11 usually has a larger specific gravity than water, so that it settles and is discharged from the discharge opening 35 at the bottom of the gas hydrate generator 11 and, for example, at a predetermined sea bottom. Stored in place (see Figure 1).

FIG. 3 is a diagram showing an outline of a gas hydrate generator 12 according to the second embodiment of the present invention. The gas hydrate generation device 12 of the present embodiment has the same basic configuration as the gas hydrate generation device 11 of the first embodiment of FIG. 2, and therefore the same configurations will be denoted by the same reference numerals and will not be described. The description will be omitted, and the differences will be mainly described below.

A jacket-type cooling device 44 is provided around the gas hydrate generator 12, and if there is a predetermined water pressure (that is, water depth), the inside of the gas hydrate generator 12 will be independent of the seawater temperature. It is configured so that a gas hydrate generation condition can be created. Further, since the gas hydrate generation reaction is an exothermic reaction, even if the seawater temperature in the installation sea area matches the gas hydrate generation temperature, the temperature inside the gas hydrate generation device 12 rises and the gas hydrate generation occurs. Although the efficiency may be reduced, by providing the jacket cooling device 44, the proper temperature can be always maintained.

Further, in this embodiment, a sparger type stirring means is adopted. That is, the stirring shaft 46 'is formed hollow, and by connecting the flexible tube 60 to the inside of the stirring shaft 46', carbon dioxide gas as a gas hydrate forming substance can be introduced. The carbon dioxide gas introduced into the stirring shaft 46 'is discharged from the tip of the stirring blade 47', and the carbon dioxide gas is discharged by using the centrifugal force of the stirring blade 47 'which is rotated by the drive of the motor 45'. The gas can be discharged as fine bubbles. Thus, with the sparger type stirring means,
This is advantageous because the effect of mixing by stirring and the effect of atomizing the bubbles can be obtained at the same time, and the problem of clogging due to the formation of hydrate lumps in the above-mentioned introduction portion does not occur.

Further, in the gas hydrate generator 12 according to the present embodiment, the water introducing section 38 is connected to the flexible tube 63 as a water supply line. As the flexible tube 63, the same flexible tube 60 as the above-mentioned gas hydrate-forming substance supplying means can be used. The flexible tube 63 is connected to a water supply device (pump or the like) not shown, and fresh water can be introduced into the gas hydrate production device 12 in the sea to dilute the salt concentration of seawater as needed. It is known that when a certain concentration of a substance such as sodium chloride exists in the raw water, the gas hydrate production conditions shift to the low temperature / high pressure side, making it difficult for gas hydrate to be produced. , It becomes possible to dilute the salt concentration in seawater and relax the gas hydrate generation conditions to the high temperature and low pressure side.

FIG. 4 is a drawing showing an outline of the gas hydrate production apparatus 13 according to the third embodiment of the present invention. This gas hydrate generation device 13 has a basic configuration, and the gas hydrate generation device 11 of the first embodiment of FIG.
Therefore, the same configurations are denoted by the same reference numerals, and the description thereof will be omitted. Below, the differences will be mainly described.

The gas hydrate producing apparatus 13 according to the present embodiment is an example of an apparatus suitable for the case where the specific gravity of the produced gas hydrate is lighter than that of seawater (that is, when the seawater does not sink and floats). Is. The gas hydrate generator 13 includes a discharge unit 2 provided at a predetermined portion of the tubular body 31.
At 1, the transfer pipe 25 is connected. A motor 23 is provided in the vicinity of the discharge part 21, and is configured to be able to transfer the gas hydrate 50 ′ having a lower specific gravity than seawater via the transfer pipe 25. Further, a pair of interface detection sensors 27, 27 are provided at predetermined positions inside the tubular body 31. The interface detection sensors 27, 27 are used to monitor the height of the boundary between the gas hydrate 50 'and the seawater surface, for example, using ultrasonic waves. In the gas hydrate generation device 13, the gas hydrate forming substance is introduced from the introduction part 37 (one place in this example) on the side surface of the device. Inside the device, the stirring blade 47
The gas-liquid contact between the seawater and the bubbles 51 of the gas hydrate-forming substance is promoted by the agitation by, and gas hydrate is generated. Since the generated gas hydrate has a lower specific gravity than seawater, it floats in the device and collects in layers between the gas storage portion 33 and seawater. That is, three layers of gas, gas hydrate 50 ', and seawater are formed inside the device. Therefore, the interface detection sensors 27, 27 monitor the interface between the gas hydrate layer (50 ′) and seawater, and derive the gas hydrate 50 ′ from the discharge part 21 to obtain the thickness of the gas hydrate layer. Make sure that (amount) is constant. With such a configuration, it is possible to continuously manufacture the gas hydrate 50 'having a lower specific gravity than seawater. The taken out gas hydrate 50 'is transferred to the transfer pipe 25 as indicated by an arrow in the figure.
Can be pumped to land, for example. Therefore, the gas hydrate generator 13 of the present embodiment
Is an apparatus suitable when the gas hydrate-forming substance as a raw material is, for example, methane gas or natural gas.

FIG. 5 is a diagram showing an outline of the gas hydrate production apparatus 14 according to the fourth embodiment of the present invention. This gas hydrate generation device 14 has a basic configuration, and the gas hydrate generation device 13 of the third embodiment of FIG.
Therefore, the same configurations are denoted by the same reference numerals, and the description thereof will be omitted. Below, the differences will be mainly described. Gas hydrate generator 14 according to the present embodiment
The lower part of the tubular body 31 is expanded downward and the opening 35 is expanded by the expanded part 32. From this wide opening 35, the source gas (gas hydrate forming substance) is introduced so that the gas hydrate 50 'can be generated. Therefore, the gas hydrate generator 14 is not connected to the flexible tube 60 as the gas hydrate-forming substance supply means. Note that FIG. 5 shows a state in which bubbles 51 ′ such as natural gas ejected from the seabed are directly introduced into the apparatus to produce a gas hydrate.

Next, a method of fixing the gas hydrate generator 11 of the present invention in the sea will be described. As described above, the method of installing the gas hydrate generation device 11 is arbitrary, and fixing is not essential, but in a sea area where the ocean current is strong, by fixing it, a stable water depth position can be maintained. An example of fixing the gas hydrate generator 11 is shown in FIG.
~ Shown in FIG.

FIG. 6 shows a state in which the gas hydrate generator 11 is moored to the seabed 200 using the wire 71. When mooring on the seabed 200 as shown in FIG. 6, a tension against the buoyancy of the gas in the gas reservoir 33 acts on the wire 71. Therefore, as shown in the figure, by installing a tension meter 72 on the wire 71 and detecting the tension applied to the wire 71, the amount of gas in the gas reservoir 33 (that is, the level of the sea level 53) can be known. . Therefore, in the case of FIG. 6, the interface level meter 42 of the gas hydrate generator 11 can be omitted.

FIG. 7 shows a state in which a float (floating offshore structure) 75 is arranged on the sea surface 300 and the gas hydrate generator 11 is moored by using a wire 73. When moored to the sea surface 300 as shown in FIG.
Compared to the case of mooring at sea (Fig. 6), it is more likely to be affected by tides and ocean currents, but it has the advantage of being easier to move to another location. In addition, it is much more stable than the method of floating in the sea.

FIG. 8 shows still another example of a method of fixing the gas hydrate generator 11 in the sea, in which three gas hydrate generators 11 are moored by a megafloat 75 'in a sea area away from land. It shows the state. In this example, the supply device 61 is also installed on the megafloat 75 ′ and can be freely moved anywhere from the coastal sea area to the open ocean, so that there is no restriction on the installation location. The gas hydrate generation device 11 according to the present invention has a simple structure and can be freely adjusted in position by being connected to the flexible tube 60. Therefore, as shown in FIG. 8, a plurality of gas hydrate generation devices 11 are arranged in parallel. It will also be easy to deploy. Therefore, it is suitable for the purpose of hydrating a large amount of carbon dioxide gas accumulated in the atmosphere and isolating it in the sea.

Although the present invention has been described with reference to various embodiments, the present invention is not limited to the above embodiments, and other embodiments are also possible within the scope of the invention described in the claims. Of course, it is applied.

For example, in the gas hydrate generators 11, 12, 13, and 14 of the first to fourth embodiments, the buoyancy is given to the device by the gas stored in the gas storage portion 33 of the tubular body 31. However, not limited to this, for example, a gas storage part such as a floating bag is provided outside the apparatus, and a gas such as a gas hydrate-forming substance or a gas such as air is separately introduced to give a buoyancy force. Is also possible. Also,
The material for giving buoyancy is not limited to gas, but a buoyancy device made of foam or the like may be attached to the outside of the device to give buoyancy.

[0046]

According to the method for producing a gas hydrate in the sea of the present invention, since the gas hydrate is produced by utilizing the water pressure in the sea, a high-pressure facility as in the case of producing a gas hydrate on land is unnecessary. . In addition, seawater temperature is 10 degrees Celsius
Cold heat is not required in the following sea areas. Furthermore, since the water required for gas hydrate production uses seawater,
No water supply equipment is required. Since the water depth position of the generator can be adjusted by the buoyancy of the generator, the desired water depth position can be easily maintained, and the optimum gas hydrate generation environment can be maintained.

Further, in the invention of the undersea storage system of carbon dioxide of the present invention, since the gas hydrate is generated by utilizing the seawater pressure and the seawater temperature, and the water depth position is controlled by utilizing the buoyancy of the generator, The energy consumption can be kept low and the device used can be simple. Therefore, the underwater storage system of the present invention is a system suitable for storing in the sea a large amount of carbon dioxide in the atmosphere, which causes global warming.

According to the underwater gas hydrate generator of the present invention, since the water depth position can be adjusted by the buoyancy of the device, it is possible to easily maintain the desired water depth position suitable for gas hydrate formation. That is, in order to generate the gas hydrate using the water pressure in the sea, it is necessary to control the water depth position of the generator so that the water pressure satisfies the gas hydrate generation condition. This water depth control,
If a fixture is used, it is necessary to lay the device in the water at a depth of 100 m or more, and it is also necessary to have strength to cope with changes in ocean currents and tidal levels, so large-scale equipment is required. On the other hand, in the device of the present invention, since position adjustment can be performed by utilizing the buoyancy of the raw material gas stored in the generator, fine adjustment is also easy, and a simple device configuration always produces the optimum gas hydrate. The environment can be maintained. further,
When installing the device, it is possible to adjust the buoyancy from the sea surface and gradually lower it, and also when performing the maintenance of the device, you can adjust the buoyancy and raise it to the sea surface. There is no need to use a large winch for maintenance or maintenance. Therefore, the gas hydrate generator of the present invention can be advantageously used, for example, in the storage of carbon dioxide in the sea.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an outline of an underwater carbon dioxide storage system.

FIG. 2 is a schematic diagram showing a schematic configuration of a gas hydrate generator according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram showing a schematic configuration of a gas hydrate generator according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram showing a schematic configuration of a gas hydrate generation device according to a third embodiment of the present invention.

FIG. 5 is a schematic diagram showing a schematic configuration of a gas hydrate generator according to a fourth embodiment of the present invention.

FIG. 6 is a diagram for explaining a seabed mooring system of a gas hydrate generator.

FIG. 7 is a drawing for explaining another example of the sea surface mooring system of the gas hydrate generator.

FIG. 8 is a drawing for explaining still another example of the sea surface mooring system of the gas hydrate generation device.

[Explanation of symbols]

11, 12, 13, 14 Gas hydrate generation device 21 Discharge part 23 Motor 25 Transfer pipe 27 Interface detection sensor 31 Cylindrical body 32 Expanding part 33 Gas storing part 35 Opening parts 37a, 37b, 37c Introducing part 39 Valve mechanism 41 pressure sensors 42 interface level meter 43a, 43b propulsion device 44 jacketed cooling device 45 motor 46 stirring shaft 47 stirring blades 50 CO ₂ hydrate 50 'gas hydrate 51 and 51' bubbles 53 sea level 53 'seawater - gas hydrate boundary 54 gas-gas hydrate boundary 60 flexible tube 61 supply device 63 flexible tube 71 wire 72 tensiometer 73 wire 75 float 81 primary reservoir 82 secondary reservoir 83 jet pump 100 undersea 200 seabed 300 sea level

Continued front page    (72) Inventor Hiroshi Tsukui             Mitsui Shipbuilding No. 1 Hachiman Kaigan Dori, Ichihara City, Chiba Prefecture             Chiba office F-term (reference) 4G075 AA03 AA04 BB10 CA74 DA02                 4G146 JA05 JB04 JC17 JC19 JC39

Claims (4)

[Claims] 1. A gas hydrate forming substance is introduced into a generator provided in the sea at a predetermined water depth, and the water depth position of the generator is adjusted by the buoyancy of the generator so that the gas hydrate forming substance and seawater Contact
A method for producing a gas hydrate in the sea, comprising producing a gas hydrate by utilizing seawater pressure. 2. The method for producing a gas hydrate in the sea according to claim 1, wherein carbon dioxide introduced from land is hydrated in the sea and then the produced CO ₂ hydrate is allowed to settle to form a storage portion on the seabed. CO2 storage system for carbon dioxide stored in the sea. 3. A submerged hydrate generator for generating a gas hydrate by utilizing seawater pressure by being brought into contact with a gas hydrate forming substance and seawater, which is a gas for storing gas. An underwater hydrate generator, which is provided with a storage unit and is configured to control the water depth position by utilizing the buoyancy of the device. 4. The gas hydrate production device according to claim 3, wherein the gas hydrate production device is connected to a flexible supply means for introducing the gas hydrate forming substance.