JP7141653B1 - Gas sampling device - Google Patents

Abstract

A gas sampling apparatus is provided that can enhance gas sampling efficiency without discharging water such as seawater from a gas guideway when sampling gas. A gas sampling apparatus (10) of the present invention comprises a gas retainer (11) provided in a through hole formed in a barge (20), and a ground (G) on the sea floor disposed in seawater below the gas retainer (11). A gas sampling tool 12 for sampling methane gas released into the seawater from the gas hydrate layer MH formed in the gas hydrate layer MH, and a lower end opening is connected to the gas sampling tool 12 so that the methane gas from the gas sampling tool 12 is collected together with the seawater in a gas retainer. 11, the upper opening of the gas guiding path 13 is arranged below the sea level in the through hole, and the methane gas is discharged from the upper opening to the gas retainer 11. At the same time, the seawater accompanying the methane gas flows back into the seawater under the water surface in the through-hole. [Selection drawing] Fig. 1

Description

TECHNICAL FIELD The present invention relates to a gas sampling device, and more particularly, to a gas sampling device for sampling methane gas that is released into the water from a methane hydrate layer formed on the surface layer of the ground on the bottom of a deep sea, lake, or the like and rises to the surface. .

Japan is a resource-poor country, and most of its fossil fuels such as petroleum and natural gas are dependent on imports from overseas. However, in recent years, a methane hydrate layer has been discovered in the seafloor in the sea near Japan, and methane gas released from the methane hydrate layer is considered promising as a fossil fuel. The methane hydrate that forms the methane hydrate layer is an ice block that freezes in a state where methane gas molecules are confined in a cage with water molecules under a specific low temperature and high pressure. This methane hydrate layer has a sand layer type and a surface layer type. Sand layer type methane hydrate is widely distributed, for example, in the Nankai Trough on the Pacific Ocean side, and is contained in a sand layer that spreads horizontally in the ground at a depth of 100 m or more from the seabed. Surface-type methane hydrates are distributed, for example, off the coast of Joetsu on the Sea of Japan side. . However, all methane hydrate layers are formed on the deep sea floor at depths of several hundred to 1000 m or more.

The sand layer type methane hydrate layer is formed in the ground at a depth of 100m or more from the seabed, and in order to extract the methane hydrate, it is necessary to drill further 100m or more from the deep seabed, and gas extraction costs are high. high cost and technically difficult problems. On the other hand, the surface-type methane hydrate layer is formed as a methane hydrate lump in the ground surface layer of the seabed. Methane gas is released into the water from this methane hydrate clump and rises to the surface as air bubbles.

The methane gas released from surface methane hydrate freezes as methane hydrate in a short period of time in seawater that satisfies the formation conditions of low-temperature, high-pressure methane hardrate. Due to the difference in specific gravity from seawater, this methane hydrate also deviates from the freezing condition while it floats in the seawater, and immediately changes to a vaporized state to become methane gas, and the bubbles float in the seawater. A columnar shape formed by floating methane gas is called a methane plume. The methane gas that forms the methane plume gradually dissolves into the seawater while the bubbles float in the seawater, and the methane gas bubbles disappear when the seawater rises several hundred meters. Therefore, the methane gas must be collected at the position where the methane gas is released on the sea floor where the methane plume rises.

Techniques for extracting methane gas from a methane plume are disclosed in Patent Documents 1 and 2, for example. In the technique of Patent Literature 1, the methane plume is covered with an inverted cup-shaped steel collecting container, and methane gas is collected on board through a collected gas lead-out pipe. In the technique of Patent Document 2, a collection membrane is used as a collection container corresponding to the collection container described in Patent Document 1, and methane gas is collected on board via a tube.

Japanese Patent No. 5771762 JP 2017-128950 A

However, in both the techniques of Patent Documents 1 and 2, while searching for the methane plume and moving the steel collection container or the collection membrane to the methane plume, the collection pipe or tube is removed from the collection container or the collection membrane. Sea water enters inside. Therefore, every time the gas sampling tool is moved to the methane plume for methane gas sampling, the methane gas must be collected after discharging the seawater in the gas guideway consisting of a pipe or tube. Harvesting efficiency decreases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above - mentioned problems. It is an object of the present invention to provide a gas sampling apparatus capable of enhancing gas sampling efficiency without discharging water such as seawater from a channel to the outside .

A gas sampling apparatus according to claim 1 of the present invention is a gas sampling apparatus which is installed on a barge floating on the surface of the water to sample natural gas generated at the bottom of the water, wherein the gas sampling apparatus is attached to the barge. A gas retention device provided in the formed through-hole, and a gas collection device placed in the water below the gas retention device to collect the gas released into the water from the gas hydrate layer formed on the ground of the water bottom. and a gas guide path having a lower end opening connected to the gas sampling tool for guiding the gas from the gas sampling tool to the gas retainer together with water, the gas guide path being on the barge side . The upper end opening is located below the water surface in the through hole, and the gas is discharged from the upper end opening to the gas retainer, and the water accompanied by the gas is discharged from the through hole. It is characterized by overflowing from the upper end opening below the water surface inside and returning to the water.

According to a second aspect of the present invention, there is provided a gas sampling apparatus according to the first aspect of the invention, wherein the gas retainer is formed in an inverted cup shape, and the lower end opening protrudes downward from the through hole. It is characterized by

Further, in the gas sampling device according to claim 3 of the present invention, in the invention according to claim 1 or claim 2 , the gas sampling device is formed in an umbrella shape that can be opened and closed, and a plurality of weight is attached.

According to the present invention, no matter where the gas hydrate layer formed on the ground of the seabed is located, when the gas there is collected through the gas guideway, water such as seawater is discharged from the gas guideway to the outside. It is possible to provide a gas sampling apparatus capable of enhancing gas sampling efficiency without performing any work.

1 is a configuration diagram showing an embodiment of a gas sampling device of the present invention; FIG. FIG. 2 is a configuration diagram mainly showing a gas retainer of the gas sampling apparatus shown in FIG. 1; FIG. 2 is a configuration diagram mainly showing a gas sampling tool of the gas sampling apparatus shown in FIG. 1;

An embodiment of the gas sampling apparatus of the present invention shown in FIGS. 1 to 3 will be described below.

As shown in FIG. 1, the gas sampling apparatus 10 of the present embodiment is provided on a barge 20 that moves on the sea surface, and searches for a methane plume P using an ultrasonic probe mounted on the barge 20. , the power of the screw 21 or the like is used to move the barge 20 to just above the methane plume P, and the gas sampling device 10 is used to sample methane gas. The position of barge 20 is always measured via GPS22.

A water removing device 23 is installed on the barge 20 , and the water removing device 23 is connected to the gas sampling device 10 via a pump 24 . The water removing device 23 removes vaporized water contained in the methane gas sampled by the gas sampling device 10 to obtain dry methane gas.

As shown in FIG. 1, the water removing device 23 includes two heat exchangers 23A for cooling the methane gas containing water after extraction, and a refrigerant tank 23B for storing the refrigerant supplied to these heat exchangers 23A. , a refrigerator 23C that cools the refrigerant that is heated and circulated by cooling the methane gas, a circulation pump 23D that circulates the refrigerant among the heat exchanger 23A, the refrigerant tank 23B, and the refrigerator 23C, and from the heat exchanger 23A and a pressure-feeding pump 23E for pressure-feeding the outflowing methane gas after water removal.

The pressure-feeding pump 23E is connected to a high-pressure gas holder 31 installed on a carrier ship 30, and pressure-feeds the methane gas after water removal to the high-pressure gas holder 31. As shown in FIG. This pressure-feeding pump 23E pressure-feeds the methane gas after dewatering to a high-pressure gas holder (not shown) installed in the barge 20, where the methane gas is temporarily stored, and then the high-pressure gas holder of the carrier ship 30 is pumped. 31 may be pumped.

As shown in FIG. 1, the gas sampling apparatus 10 of the present embodiment includes a gas retainer 11 provided in a through-hole formed in a barge 20 and a A gas sampling tool 12 for sampling methane gas bubbles M of a methane plume P formed on a surface type methane hydrate layer MH on the sea bottom, and a tubular shape connecting the gas retainer 11 and the gas sampling tool 12. and a gas guide path 13 of

As shown in FIG. 2, the gas retention device 11 includes an elongated straight body portion 11A, a top portion 11B formed by closing the upper end of the straight body portion 11A, and an opening 11C formed at the lower end of the straight body portion 11A. , the top portion 11A protrudes into the air from the through hole, and the lower end opening 11C protrudes from the through hole into the seawater. The barge 20 floats on the sea surface, and the seawater reaches the middle of the straight body portion 11A of the gas retainer 11 fitted in the through hole. A space between the top portion 11B of the gas retention device 11 and the sea surface in the through hole is formed as a retention space for methane gas. A gas guide path 13 is connected to the lower end of the gas retainer 11 through a connector 14 in a state of being submerged in seawater. The wavy lines in FIGS. 1 and 2 indicate the sea level.

As shown in FIGS. 1 and 2, the connecting member 14 is, for example, formed like a string, and both ends thereof are connected to the lower portion of the inner peripheral surface of the gas retainer 11 and the upper end portion of the outer peripheral surface of the gas guide path 13, respectively. , the gas introduction path 13 is suspended from the gas retainer 11 via a connector 14, and the upper end opening of the gas introduction path 13 is positioned below the sea surface. A plurality of connectors 14 are connected to the inner peripheral surface of the gas retainer 11 and the outer peripheral surface of the gas guide path 1 at equal intervals in the circumferential direction. A ring plate mounted between the gas retainer 11 and the gas guide path 13 can be used instead of the plurality of connectors 14 . This ring plate has, for example, a plurality of flow holes formed at equal intervals in the circumferential direction of the ring plate, and these flow holes serve as passages for seawater. Therefore, the gas guide path 13 is suspended from the gas retainer 12 via the connector 14, and its upper end opening penetrates from the lower end opening of the gas retainer 11 as described above, and is positioned slightly below the sea level. ing.

The gas guide path 13 is formed of, for example, a flexible material in a cylindrical shape, and its length and diameter can be appropriately adjusted according to the depth and scale of the methane plume P. If the gas guide path 13 is cylindrical, it can be formed with a diameter of, for example, 1 m to several meters, and is formed as a flexible bellows-like assembly unit using a flexible material. The units can be connected together and adjusted as a gas guideway 13 depending on the gas sampling depth. The gas guide path 13 only needs to function as a guide path for the methane gas bubbles M to float together with the seawater, and the connection between the assembly units does not have to be strictly airtight. In order for the bubbles M to float smoothly in the gas guide path 13, it is preferable that the peripheral surface is formed as smooth as possible.

As shown in FIGS. 1 and 2, the upper end opening of the gas guideway 13 is positioned slightly below the sea surface in the through-hole of the barge 20, and the air bubbles M from the upper end opening of the gas guideway 13 pass through the sea surface. While the seawater is discharged into the gas retention space as indicated by an open arrow X, the seawater that floats along with the air bubbles M flows back into the seawater as indicated by an arrow Y from the upper end opening of the gas guide path 13 . In conventional equipment, pipes and tubes, which are gas guide paths, are connected to methane gas collection containers or collection membranes to collect only gas, so seawater that has entered the pipes or tubes is temporarily discharged to the outside. work efficiency was not good.

A gas sampling tool 12 is connected to the opening at the lower end of the gas guide path 13 , and the bubbles M of the gas plume P are introduced into the gas guide path 13 via the gas sampling tool 12 . The gas sampling tool 12 is configured to open and close like an umbrella as shown in FIGS. Umbrella-shaped gas sampling device 12 has a cylindrical ring 12A that fits into the lower end opening of gas guide path 13, and is spaced equally in the circumferential direction of ring 12A so that it swings around one end as indicated by an arrow. an axis 12C depending from the center of the ring 12A and longer than the first bone members 12B; a sliding member (not shown) sliding along the axis 12C; A plurality of second rib members 12D, one end of which is connected to the moving member and the other end of which is connected to the top of the first rib member 12B, and the sliding member are slid upward along the axis 12C to open into a polygonal pyramid shape. and a film 12E attached to a plurality of first bone members 12B, and is configured to collect methane gas with the film 12E opened in a polygonal pyramid shape by operating the sliding member of the shaft 12C. Further, weights 12F are attached to the free ends of some of the first rib members 12B that are evenly spaced among the plurality of first rib members 12B. Therefore, the gas sampling device 12 is kept open until the weights 12F hanging from the free ends of the plurality of first rib members 12B land on the seabed ground as shown in FIGS. The gas guide path 13 is extended, and the methane gas bubbles M are guided to the gas guide path 13 by the membrane 12E.

The methane gas bubbles M guided from the gas sampling tool 12 to the gas guide path 13 are mixed with the seawater in the gas guide path 13, and the bubbles M are accompanied by the seawater and rise while gradually increasing in size. 1. Sea water outside the gas sampling device 12 intrudes as indicated by the white arrow Z in FIG. At this time, the bubbles M rising in the gas guide path 13 push aside the seawater from the upper end opening and are discharged into the space inside the top portion 11B of the gas retainer 11 as indicated by the white arrow X in FIGS. On the other hand, the seawater overflowing from the upper end opening of the gas guideway 13 circulates into the seawater within the through hole as indicated by the arrow Y in FIGS. In this way, seawater overflows from the upper end opening of the gas guide path 13 and seawater enters the gas sampling tool 12 to form a circulating flow of seawater. This phenomenon causes a difference in specific gravity between seawater containing bubbles M inside the gas guide path 13 and seawater containing no bubbles outside the gas guide path 13 . It is understood that this difference in specific gravity acts as a driving force to generate a circulation flow of seawater indicated by arrows Y and Z in FIG.

In this way, when the extraction of methane from one methane plume P is completed and the barge 20 is moved to another methane plume P to extract methane gas, the seawater in the gas guideway 13 is not discharged. Methane gas can be collected by using it as a circulation flow. That is, in the present embodiment, when collecting methane gas from a new methane plume P, the seawater in the gas guideway 13 is circulated without being discharged. This simplifies the extraction work and increases the efficiency of methane gas extraction.

As described above, according to this embodiment, the gas sampling device 10 for sampling methane gas from the seabed includes the gas retainer 11 provided in the through hole formed in the barge 20 and the gas retainer 11 below the gas retainer 11. a gas sampling tool 12 for sampling methane gas released into the water from the methane gas hydrate layer MH formed on the ground of the seabed and placed in the seawater of the seawater; a gas guide path 13 for guiding the methane gas bubbles M from the tool 12 to the gas retainer 11 together with the seawater, and the gas guide path 13 has an upper end opening disposed below the water surface in the through hole of the barge. Since the air bubbles M are discharged from the upper end opening of the gas guide path 13 to the gas retainer 11 and the seawater accompanying the air bubbles M is recirculated into the seawater under the water surface in the through-hole, the gas from the gas guide path 13 Since there is no seawater discharge operation, the methane gas extraction operation is simplified, and the methane gas extraction efficiency can be improved.

In addition, since the gas retainer 11 is formed in an inverted cup shape, and the lower end opening 11C protrudes downward from the through hole of the barge 20, the gas is guided when the seawater flowing out from the upper end opening of the gas guide path 13 circulates. A descending flow can be formed by the channel 13 .

In addition, the gas sampling tool 12 is formed in an umbrella shape that can be opened and closed, and a plurality of weights 12F are attached to the outer peripheral end thereof, so that the posture of the gas sampling tool 12 above the methane plume P can be stabilized. .

It should be noted that the present invention is not limited to the above-described embodiments, and each component can be appropriately changed as necessary without departing from the gist of the present invention.

REFERENCE SIGNS LIST 10 gas sampling device 11 gas retainer 11C lower end opening 12 gas sampling tool 12F weight 13 gas guideway 20 barge M bubble MH methane hydrate layer (surface layer methane hydrate)
G Ground

Claims (3)

A gas sampling device installed on a barge floating on the surface of the water for sampling natural gas generated at the bottom of the water, the gas sampling device comprising: a gas retainer provided in a through hole formed in the barge; a gas sampling device arranged in the water below the gas retention device for sampling gas released into the water from a gas hydrate layer formed on the ground of the water bottom; and a lower end opening connected to the gas sampling device. a gas guideway for guiding the gas together with water from the gas sampling tool to the gas retainer, wherein the gas guideway is suspended from the barge side, and the upper end opening thereof is the through hole. The gas is discharged from the upper end opening to the gas retainer, and the water accompanied by the gas overflows from the upper end opening below the water surface in the through hole. A gas sampling device characterized by refluxing into the water. 2. The gas sampling apparatus according to claim 1, wherein said gas retention device is formed in an inverted cup shape, and a lower end opening protrudes downward from said through hole. 3. The gas sampling device according to claim 1, wherein said gas sampling device is formed in an umbrella shape that can be opened and closed, and a plurality of weights are attached to the outer peripheral edge thereof.

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