JP4773647B2 - Gas hydrate transfer device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for mining a gas hydrate existing in the ground, and particularly to a technique for conveying a fluid containing the excavated gas hydrate through a pipe.
[0002]
[Prior art]
A gas hydrate is an icy solid substance composed of gaseous gas molecules and water molecules. Needless to say, a water molecule consists of one oxygen atom and two hydrogen atoms, but in the liquid state, a plurality of water molecules are bonded or separated, and dozens of water molecules are bonded. The state is called a cluster structure. The cluster structure is unstable in a liquid state, but becomes stable when pressurized or cooled, and the number of water molecules constituting the cluster structure increases.
[0003]
When sufficient gas molecules are present here, gas molecules are taken into the inside of the crevices and hydrates are generated. Those in which gas molecules are taken into the voids of the cluster structure are called gas hydrates, and those in which methane molecules are taken in are called methane hydrates.
[0004]
It has been clarified that gas hydrate containing a large amount of methane, that is, methane hydrate, exists in the natural world under permafrost and in submarine ground at a depth of about 500 m or less. The reserves are extremely large, and there are great expectations for next-generation energy resources to replace conventional fossil fuels.
[0005]
[Problems to be solved by the invention]
The existence of methane hydrate is supported by acoustic exploration and trial drilling of the seabed, but due to its unique properties, it is necessary to establish a unique drilling technique different from conventional fossil fuels such as oil and natural gas. .
[0006]
For example, what we are trying to mine is methane gas or other useful gas, which does not need water, but because it is combined with useful gas to form a hydrate, it is pulled up to the sea. Consumes a lot of energy. However, when trying to suck up the ice mass of methane hydrate through a pipe hanging from the sea to the bottom of the sea, the ambient temperature may increase as it approaches the sea, and the methane hydrate decomposes and the water concentration increases. In other words, useless energy is consumed to suck up water that has no utility value.
[0007]
In addition, if the methane hydrate ice blocks are sucked up through the pipes, it is expected that the ice blocks freeze and block at the joints of the pipes. When clogging occurs inside the piping, it is very dangerous because not only a great deal of energy is required to solve this problem, but also the equipment for excavation can be seriously damaged.
[0008]
This invention is made | formed in view of said situation, and aims at extracting the gas hydrate which exists in the ground efficiently and safely.
[0009]
[Means for Solving the Problems]
As means for solving the above problems, the following configuration is adopted. That is, the gas hydrate transfer device according to claim 1 of the present invention is a gas hydrate transfer device for transferring a fluid in a state where gas hydrate, gas and water are mixed, through a pipe, and drains water from the inside of the pipe. Draining means , a cylindrical body that is installed in a position spaced apart from the inner wall of the pipe, and has a large number of openings on the side surface, and the flow of the fluid upstream of the cylindrical body And a swirl flow imparting means for imparting a swirl flow .
[0010]
Gas hydrate conveying device of the reference example of the present invention is to install a tubular body aligned lengthwise at a position spaced from the inner wall of the front Symbol pipe, forming a number of openings on the side surface of the tubular body It is characterized by that.
[0011]
Gas hydrate conveying device of the reference example of the present invention, upstream from previous SL cylindrical body, characterized in that a swirling flow imparting means for imparting the swirling flow to the fluid stream.
[0012]
In the present invention, from the relationship between density and velocity distribution in the fluid flowing through the inside of the pipe, the higher the density, the closer the inner wall of the pipe, and the lower the density, the closer the center of the pipe. Therefore, by utilizing this property, a relatively low density gas and gas hydrate out of gas hydrate, gas, and water are allowed to flow along the center of the pipe, and high density water flows along the inner wall of the pipe. And if the water which flows along an inner wall is discharged | emitted outside, the density | concentration of the water in the fluid which flows through piping will fall.
[0013]
Further, in the present invention, the cylindrical body is installed in the pipe with the length direction aligned, and the relatively low density gas and gas hydrate are inside the cylindrical body, and the high density water is the cylindrical body. It is desirable to form a large number of openings on the side surface of the cylindrical body. For example, a cylindrical body is manufactured with a perforated plate or a net-like mesh material. According to this, water is easily moved from the center of the pipe to the outside, and the water separation efficiency is increased.
In the present invention, it is desirable to provide swirl flow imparting means for imparting a swirl flow to the fluid flow upstream of the cylindrical body. According to this, the force with which high density water tries to move outward is enhanced by the action of centrifugal force, and the water separation efficiency is further increased.
[0014]
A gas hydrate transfer device according to a reference example of the present invention is a gas hydrate transfer device that transfers a fluid containing gas hydrate and gas and water through a pipe, and detects the temperature of the fluid inside the pipe. It is characterized by comprising temperature detecting means and heating means for heating the fluid based on the detection result of the temperature detecting means.
[0015]
Gas hydrate conveying device of the reference example of the present invention, prior Symbol heating means, wherein the conductive path of the heat medium provided inside the pipe, a pump for circulating the heating medium in the conductor passage, wherein the temperature detection And a heater for heating the heating medium based on the detection result of the means.
[0016]
In the reference example of the present invention , the clogging inside the pipe is prevented by detecting this and heating the fluid so that the temperature of the fluid inside the pipe does not drop to a temperature at which clogging easily occurs.
[0017]
A gas hydrate transfer device of a reference example of the present invention is a gas hydrate transfer device that transfers a fluid in a state where gas hydrate and gas and water are mixed through a pipe, and the pipe is divided into a plurality of parts. Pressure detecting means for detecting the pressure of the fluid is installed for each part, and the presence or absence of the blockage and the part where the blockage occurred are specified based on the detection result of the pressure detection unit.
[0018]
Reference Example of gas hydrate conveying apparatus of the present invention has established a heating means for heating the fluid before SL in each part, heating the identified part inside the fluid based on the detection result of said pressure detecting means It is characterized by that.
[0019]
In the reference example of the present invention, if the pressure is significantly different before and after a certain part (high pressure on the upstream side and low pressure on the downstream side), it is specified that the part is blocked. Once occlusion occurs, the occlusion is resolved by heating the fluid inside the part.
[0020]
A gas hydrate transfer device of a reference example of the present invention is a gas hydrate transfer device that transfers a fluid in a state where gas hydrate and gas and water are mixed through a pipe, and the pipe is divided into a plurality of parts. A temperature detecting means for detecting the temperature of the fluid for each part and a heating means for heating the fluid are installed, and the fluid is heated for each part based on the detection result of the temperature detecting means. To do.
[0021]
In the reference example of the present invention, the temperature of the fluid is detected for each part, and if there is a part that has fallen to a temperature that is likely to cause clogging, the fluid flowing inside this part is heated to prevent clogging inside the pipe. Is done.
[0022]
A gas hydrate transfer device according to a reference example of the present invention is a gas hydrate transfer device that transfers a fluid in a state where gas hydrate and gas and water are mixed through a pipe, and temporarily transfers the fluid in the middle of the pipe. A space is provided for promoting the decomposition of the gas hydrate, the water accumulated in the space is discharged to the outside, and the gas is conveyed through the pipe.
[0023]
In the reference example of the present invention, a temporary reservoir of fluid is provided to promote decomposition of gas hydrate, and excess water is discharged to the outside, so that only the gas or the concentration of the gas is increased beyond that. Is transported.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of a gas hydrate transfer apparatus according to the present invention will be described with reference to FIGS.
FIG. 1 shows a gas hydrate mainly containing methane (that is, methane hydrate) buried in the seabed and offshore facilities that excavate natural gas mainly composed of methane. In the figure, reference numeral 1 is a platform installed on the ocean, 2 is a high-concentration facility that dehydrates the mined methane hydrate to increase the concentration, 3 is a production facility that generates methane hydrate from the mined methane gas, and 4 Hydrate piping for conducting methane hydrate from the underground hydrate layer H, 5 is a gas piping for conducting methane gas from the underground gas layer. Methane hydrate having a high concentration or generated on the platform 1 is transported on the sea by a dedicated transport ship 6 and stored in a storage facility 7 provided on land.
[0025]
The gas hydrate transfer apparatus according to the present invention is provided in the hydrate pipe 4. In the hydrate pipe 4, a fluid in a state where methane hydrate MH, methane gas g, and water W are mixed is conveyed. As shown in FIG. 2, a cross section is provided at a position near the lower end of the hydrate pipe 4. A cylindrical body (cylindrical body) 10 is installed with the length direction aligned at a position spaced from the inner wall of the circular hydrate pipe 4 and the centers thereof aligned. The cylindrical body 10 is fixed to the inner wall of the hydrate pipe 4 with the upper and lower ends enlarged in a funnel shape. The cylindrical body 10 is obtained by processing a perforated plate, and a large number of holes (openings) 10a are formed on the side surface.
[0026]
The hydrate pipe 4 is provided with a pump (discharge means) 12 that discharges water from a space 11 formed between the cylinder body 10 and the opening / closing valve V.
[0027]
In the gas hydrate transfer device configured as described above, in the fluid flowing through the hydrate pipe 4, the higher the density, the closer the inner wall of the pipe flows from the relationship between the density and the velocity distribution. The smaller one uses the property of trying to flow through the center of the tube. More specifically, the fluid flowing through the hydrate pipe 4 has a velocity distribution in which the flow velocity increases toward the center of the tube and decreases toward the inner wall due to friction with the inner wall. Here, considering an arbitrary cross section, the energy of the fluid is considered to be constant at the center and the periphery (near the inner wall) of the tube, so the density of the fluid flowing in the center of the tube is ρ1, the flow velocity is v1, and the periphery is the density of the fluid flowing through [rho] 2, when the flow velocity and v2, a ^{ρ1 × v1 2/2 = ρ2} × v2 2/2. Here, since v1> v2, ρ1 <ρ2 is an absolute condition to satisfy the above relational expression. That is, methane gas and methane hydrate having a relatively low density flow in the center of the pipe, and water having a high density flows in the periphery.
[0028]
Due to such properties, in the hydrate pipe 4, methane gas g and methane hydrate MH flow inside the cylindrical body 10, and water flows in the space 11. Therefore, when the water flowing through the space 11 is discharged to the outside by the pump 12, the concentration of the water in the fluid flowing through the hydrate pipe 4 decreases.
[0029]
According to this, energy consumed to suck up water having no utility value can be saved, and methane hydrate excavation can be carried out efficiently.
[0030]
It should be noted that the hydrate transport device of this embodiment is effective not only at the lower end of the hydrate pipe 4 but at any location. It is more effective to install a plurality of hydrate transfer devices in the hydrate pipe 4.
[0031]
Next, a second embodiment of the gas hydrate transfer apparatus according to the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the component already demonstrated in the said 1st Embodiment, and description is abbreviate | omitted.
In the present embodiment, a swirler (swirl flow imparting means) 13 that provides a swirl flow to the fluid flow is provided upstream of the cylindrical body 10, that is, on the lower end side of the hydrate pipe 4. The swirler 13 is a device that creates a swirl flow by creating a flow in one circumferential direction along the inner wall of the tube.
[0032]
According to this, the centrifugal force acts on each element constituting the fluid by giving the swirl flow, and the force for moving the dense water to the outside is strengthened, so that the water separation efficiency is further increased. Hydrate excavation can be carried out more efficiently.
[0033]
Next, the gas hydrate conveyed equipment according to the reference example 1 of the present invention shown in FIG. In addition, the same code | symbol is attached | subjected to the component already demonstrated in said each embodiment, and description is abbreviate | omitted.
In this reference example , the hydrate pipe 4 has a double-pipe structure, and the fluid flows further inside the inner pipe 4a. The gas hydrate transfer device of the present reference example includes temperature detection means 20 that detects the temperature of the fluid inside the tube 4a, and heating means 21 that heats the fluid based on the detection result of the temperature detection means 20. It is configured.
[0034]
The heating means 21 uses a space 22 between the inner pipe 4a and the outer pipe 4b as a hot water conduction path as a heating medium, and is a pump provided in the middle of a hot water circulation path 23 including the space 22 as a part. 24 and a heater 25 for heating the hot water.
[0035]
In this gas hydrate transfer device, when the temperature of the fluid inside the pipe 4a falls below a certain temperature, the heater 25 is operated to heat the hot water, and the heated hot water is allowed to flow into the space 22 so that the hydrate pipe 4 Keep the inside at a constant temperature.
[0036]
According to this, the temperature at which the heater 25 is operated is set to be higher than the temperature at which the fluid in the hydrate pipe 4 is likely to block, thereby preventing blockage due to freezing of methane hydrate. As a result, methane hydrate excavation can be carried out safely and smoothly.
[0037]
The hydrate transport device of this reference example is more effective when the hydrate piping 4 is divided into a plurality of parts and the hydrate transport device is individually installed in each part.
[0038]
Next, the gas hydrate conveyed equipment according to the reference example 2 of the present invention shown in FIG. In addition, the same code | symbol is attached | subjected to the component already demonstrated in each said embodiment and reference example , and description is abbreviate | omitted.
In this reference example , a plurality of parts a, b, c... Divided in the length direction are set in the double-structure hydrate pipe 4, and the pressure for detecting the pressure of the internal fluid is detected for each part. Detection means 30 is installed. In addition, a heating unit 21 similar to the above is installed for each part, and a control unit 31 that operates the heating unit 21 of the part that has been blocked based on the detection result of the pressure detection unit 30 is installed.
[0039]
In this gas hydrate transfer device, if the pressure is greatly different before and after a certain part, it is specified that the part is clogged or is clogged. Once this state is specified, the heating means 21 installed in the part is operated to heat the fluid inside.
[0040]
According to this, it is possible to prevent clogging due to freezing of methane hydrate by heating the part that has been clogged or is causing clogging, and thus excavation of methane hydrate can proceed safely and smoothly.
[0041]
In this reference example, it is more effective to combine the temperature detection means 20 with each heating means 21 to constitute the gas hydrate transport device of Reference Example 2 and simultaneously perform blockage prevention by temperature detection and pressure detection. is there.
[0042]
Next, the gas hydrate conveyed equipment according to Embodiment 3 of the present invention shown in FIG. In addition, the same code | symbol is attached | subjected to the component already demonstrated in each said embodiment and reference example , and description is abbreviate | omitted.
In the present embodiment, a box 41 having a space 40 for temporarily storing fluid is provided in the middle of the hydrate pipe 4. The box 41 is provided with a heater 42 that heats the fluid accumulated inside, and a pump 43 that discharges the water accumulated in the space 40 to the outside.
[0043]
In this hydrate transfer device, the fluid sucked up to the space 40 through the hydrate pipe 4 temporarily stops, and during this time, the fluid is heated to decompose methane hydrate. And the increasing water is discharged | emitted outside from the space 40 with the pump 43, and the fluid with which the density | concentration of the remaining methane gas or methane gas increased further is conveyed upwards.
[0044]
According to this, energy consumed to suck up water having no utility value can be saved, and methane hydrate excavation can be carried out efficiently.
[0045]
【The invention's effect】
As described above, according to the present invention, a relatively low density gas and gas hydrate out of gas hydrate, gas, and water are inside the cylindrical body, and high density water is outside the cylindrical body. Since the concentration of water in the fluid flowing in the pipe is lowered by discharging the water flowing between the inner wall of the pipe of the cylindrical body and the cylindrical body to the outside, the water that is not useful is sucked up Energy can be saved, and gas hydrate excavation can be performed efficiently.
[0046]
According to the reference example of the present invention , it is possible to prevent clogging inside the pipe by detecting this and heating the fluid so that the temperature of the fluid inside the pipe does not decrease to a temperature at which clogging easily occurs. This allows gas hydrate excavation to proceed safely and smoothly.
[0047]
According to the reference example of the present invention , it is possible to prevent the clogging of the inside of the pipe by heating the part identified as being clogged due to the difference in pressure, thereby excavating methane hydrate. It can proceed safely and smoothly.
[0048]
According to the reference example of the present invention , the temperature of the fluid is detected for each part, and if there is a part that has been lowered to a temperature at which it is likely to cause clogging, the fluid flowing inside this part is heated, so This can prevent methane hydrate excavation safely and smoothly.
[0049]
According to the reference example of the present invention, a temporary reservoir of fluid is provided to promote decomposition of gas hydrate, and excess water is discharged to the outside, so that only gas or the concentration of gas is increased beyond that. Since the fluid is transported, it is possible to save the energy consumed for sucking up water that is not useful, thereby enabling efficient gas hydrate drilling.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment according to the present invention, and is a schematic diagram showing an offshore facility excavating methane hydrate and natural gas buried in seabed ground.
FIG. 2 is also a diagram showing the first embodiment, and is a side sectional view showing a structure of a gas hydrate transfer device provided in a hydrate pipe.
FIG. 3 is a side sectional view showing a structure of a gas hydrate transfer device provided in a hydrate pipe, showing a second embodiment according to the present invention.
FIG. 4 is a side sectional view showing the structure of a gas hydrate transfer device provided in a hydrate pipe, showing Reference Example 1 of the present invention.
FIG. 5 is a view showing a reference example 2 of the present invention , and is a side sectional view showing a structure of a gas hydrate transfer device provided in a hydrate pipe.
6 is a view showing a third embodiment of the present invention , and is a side sectional view showing a structure of a gas hydrate transfer device provided in a hydrate pipe. FIG.
[Explanation of symbols]
4 Hydrate piping 10 Cylindrical body (tubular body)
12 Pump (Discharge means)
13 slewing machine (swirl flow applying means)
20 Temperature detection means 21 Heating means 30 Pressure detection means 31 Control unit

Claims (1)

A gas hydrate transfer device for transferring a fluid in a state where gas hydrate and gas and water are mixed through a pipe,
Drainage means for draining from the inside of the pipe ;
A cylindrical body that is installed with the length direction aligned at a position spaced from the inner wall of the pipe, and forms a large number of openings on the side surface;
A gas hydrate conveying apparatus comprising: a swirl flow imparting unit that imparts a swirl flow to the fluid flow upstream of the cylindrical body .

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