JP2018080545A - Gas hydrate recovery apparatus and gas hydrate recovery method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas hydrate recovery apparatus capable of efficiently melting gas hydrates, and a gas hydrate recovery method.SOLUTION: A bulk gas hydrate m and a sediment are supplied into a gasification tank 5 together with water at a water bottom 2, so as to separate the bulk gas hydrate m from the sediment due to the difference in specific gravity. The bulk gas-hydrate m is melted to generate a gas g. While the gas g inside the gas tank 5 is taken out for recovery, the sediment is discharged outside the gas tank 5.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a gas hydrate recovery device for collecting and recovering a massive gas hydrate from the bottom of the water together with the water at the bottom for the purpose of melting the gas hydrate and recovering the gas such as methane by taking it outside. More particularly, the present invention relates to a gas hydrate recovery apparatus and a gas hydrate recovery method for efficiently melting gas hydrate.

  Various gas hydrate recovery devices for recovering methane gas hydrate present at the bottom of the sea or lake (hereinafter sometimes referred to as water bottom) have been proposed (see, for example, Patent Document 1).

  Patent Document 1 proposes a gas hydrate recovery device that recovers gas generated by melting massive gas hydrate by moving massive gas hydrate together with water at the bottom of the water to a water facility. In the separator, the collected gas hydrate and the surface layer water were mixed, and the gas generated as the gas hydrate melted was collected.

  The bottom sediment flows into the separator along with the massive gas hydrate. This earth and sand accumulates on the bottom of the separator, causing a problem that the passage formed in the bottom of the separator is blocked. It is expected that every time the passage at the bottom of the separator is blocked with earth and sand, the gas hydrate recovery operation must be interrupted to clean the inside of the separator. Therefore, it becomes difficult to recover the gas hydrate continuously for a long time.

  Since melting of the gas hydrate is an endothermic reaction, the temperature of the surface layer water supplied from the upstream side of the separator decreases as it moves downstream. Therefore, it is expected that the gas hydrate does not efficiently melt on the downstream side of the separator.

  The gas hydrate accumulated in the separator freezes the dissolved water of the gas hydrate and the seawater of the surrounding seawater by the endothermic reaction when the gas hydrate decomposes, and forms a large lump of gas hydrate and ice. May grow. When a mass of gas hydrate and ice is formed, the gas hydrate has a small surface area and is difficult to melt. Therefore, it is expected that it is difficult to efficiently melt the gas hydrate with the conventional separator.

JP2015-31097A

  The present invention has been made in view of the above problems, and an object thereof is to provide a gas hydrate recovery apparatus and a gas hydrate recovery method capable of efficiently melting gas hydrate.

A gas hydrate recovery device for achieving the above object includes a gas hydrate recovery device including a gasification tank for recovering a massive gas hydrate collected from the bottom of the water together with water at the bottom of the water. A supply port for guiding the gas hydrate in a lump together with the water in the bottom to the inside of the gasification tank, a gas recovery unit for taking out the gas in the gasification tank to the outside, and a bottom of the gasification tank And a discharge port for discharging the earth and sand collected together with the water at the bottom of the water to the outside.

  The gas hydrate recovery method for achieving the above object is to collect a gas hydrate from the bottom of the water together with water at the bottom of the gas in a gasification tank and recover a gas generated by melting the gas hydrate in the form of a mass. In the gas recovery method, the supply step of supplying the massive gas hydrate and earth and sand together with the water in the bottom into the gasification tank, and the massive gas hydrate and earth and sand are separated by a difference in specific gravity. A separation step, a melting step for generating gas by melting the massive gas hydrate, a recovery step for taking out and collecting the gas inside the gasification tank, and the earth and sand to be separated in the separation step. A discharge step of discharging to the outside of the gasification tank.

  According to the gas hydrate recovery device and the gas hydrate recovery method of the present invention, since the earth and sand recovered together with the massive gas hydrate can be discharged from the gasification tank, the gasification tank is used continuously for a long time. be able to. It is advantageous to efficiently melt the gas hydrate.

It is explanatory drawing which illustrates the gas hydrate collection | recovery apparatus of this invention. It is explanatory drawing which illustrates the gasification tank of FIG. It is explanatory drawing which illustrates the gasification tank of FIG. 2 by AA arrow view. It is explanatory drawing which illustrates the modification of the gasification tank of FIG. It is explanatory drawing which illustrates the modification of the gasification tank of FIG. It is explanatory drawing which illustrates the modification of the gasification tank of FIG.

  Hereinafter, a gas hydrate recovery apparatus and a gas hydrate recovery method of the present invention will be described based on the embodiments shown in the drawings.

  As illustrated in FIG. 1, a gas hydrate recovery device 1 of the present invention excavates a methane gas hydrate m existing in a water bottom 2 that is the bottom of a sea or a lake, and collects a massive gas hydrate m. 3 and a riser pipe 4 that conveys the gas hydrate m collected by the excavation mechanism 3 upward from the vicinity of the water bottom 2.

  The excavation mechanism 3 can be composed of, for example, a drill bit or an underwater heavy machine. The configuration of the excavation mechanism 3 is not limited to this, and it is sufficient that the excavation mechanism 3 has a configuration in which the bottom 2 is excavated and the massive gas hydrate m is sent to the recovery port 4 a at the lower end of the riser pipe 4.

  The riser tube 4 can be formed of, for example, a cylindrical body that extends in the vertical direction. A recovery port 4 a at the lower end of the riser pipe 4 is disposed in the vicinity of the water bottom 2.

  The upper end of the riser pipe 4 is directly or indirectly connected to the gasification tank 5. The gasification tank 5 is installed in a structure 6 such as a ship or a floating body arranged near the water surface. The structure 6 in which the gasification tank 5 is installed is not limited to a ship or the like disposed near the water surface, but may be configured by a land structure or a floating body disposed in water.

The gasification tank 5 has a function of gasifying the massive gas hydrate m. The gasification tank 5 includes a gas recovery unit 7 that extracts an internal gas g to the outside, and a gas supply line 8 that is connected to the gas recovery unit 7 at one end. The other end of the gas supply line 8 can be connected to a storage tank that stores the gas g, a device that transports the gas g, and a pipeline that transports the gas g to a consumption area. In order to continuously supply the gas g to the gas supply line 8, the gasification tank 5 may have a function of storing a predetermined amount or more of the gas hydrate m.

  The gasification tank 5 is directly or indirectly connected to a discharge pipe 9 extending toward the bottom 2. The discharge pipe 9 is formed of a cylindrical body, for example, and the lower end portion 9 a is disposed in the vicinity of the water bottom 2. In the present specification, the vicinity of the bottom means a region from the bottom 2 up to about 10 m. The range in the vicinity of the water bottom is not limited to the above and can be set as appropriate. The range in the vicinity of the water bottom may be, for example, a range from the water bottom 2 up to 2 m, or a range from the water bottom 2 up to 50 m.

  The massive gas hydrate m excavated and collected by the excavation mechanism 3 at the bottom 2 is sent to the recovery port 4 a at the lower end of the riser pipe 4. Since the gas hydrate m contains a gas resource such as methane gas and has a relatively small specific gravity, the gas hydrate m moves upward in the riser pipe 4 by buoyancy.

  Since the water pressure decreases and the temperature increases as it approaches the water surface, the gas hydrate m rising in the riser pipe 4 may melt and generate gas g bubbles. Since the amount of bubbles increases as it approaches the upper end of the riser tube 4, the density of the fluid in the riser tube 4 decreases as it approaches the upper end.

  Since the specific gravity difference between the recovery port 4a and the upper end of the riser pipe 4 is increased, an upward flow is generated in the riser pipe 4 due to the specific gravity difference. The same effect as a so-called air lift pump occurs. By this upward flow, water and earth and sand (hereinafter sometimes referred to as slurry) in the vicinity of the bottom 2 together with the massive gas hydrate m are sucked up by the riser pipe 4 and collected in the gasification tank 5. A power source such as a pump is installed in the riser pipe 4 or a gas is blown into the riser pipe 4 to generate bubbles so that an upward flow is actively generated in the riser pipe 4. Good.

  When a gas is blown into the riser pipe 4, a gas lift mechanism is installed that collects the gas g such as methane from the gasification tank 5 or the gas supply line 8 and supplies the gas g into the riser pipe 4. It is desirable. Since this gas lift mechanism does not mix other gases such as air with the gas g recovered via the gas supply line 8, the quality of the recovered gas g can be easily maintained constant. In addition, disasters such as combustion and explosion can be avoided.

  In addition, it is desirable that the gas lift mechanism is configured to supply the gas g from a position in the middle of the riser pipe 4 where the water depth is shallower than 300 m and includes 300 m. This is advantageous in avoiding the problem that the gas g supplied into the riser pipe 4 regenerates the gas hydrate. It is possible to avoid a problem that the regenerated gas hydrate adheres to the inner wall surface of the riser pipe 4 to block the flow path or prevent the upward flow.

  Moreover, the gas g can be made into a low pressure rather than blowing the gas g supplied to the inside of the riser pipe 4 in the vicinity of the water bottom. Since the gas g to be blown becomes a low pressure, it can be avoided that the bubbles of the gas g become excessively large inside the riser pipe 4 and prevent the lifting.

The bottom 2 where the gas hydrate m exists is, for example, a depth of 400 m or more, and the water temperature of the bottom 2 is 5 ° C. or less. On the other hand, the circumference of the gasification tank 5 installed in the structure 6 such as a ship is about 20 ° C., for example. Since the temperature in the gasification tank 5 is relatively higher than that of the bottom 2, the gas hydrate m is melted in the gasification tank 5 to generate gas g. Further, the gas g generated by melting the gas hydrate m during the flow through the riser pipe 4 is recovered in the gasification tank 5.

  Gas g such as methane in the gasification tank 5 is taken out from the gas recovery unit 7 to the gas supply line 8 outside the gasification tank 5. The gas recovery unit 7 can be constituted by, for example, a check valve that allows gas to move only from the inside of the gasification tank 5 to the outside.

  The earth and sand inside the gasification tank 5 is discharged to the outside through the discharge pipe 9. Therefore, it is possible to suppress sediment from being deposited in the gasification tank 5. Since it is possible to suppress sedimentation and blockage of earth and sand inside the gasification tank 5 and the capacity of the gasification tank 5 being pressed due to the accumulation of earth and sand, the gasification tank 5 can be continuously operated for a long time. . It is advantageous to efficiently melt the gas hydrate m. In this specification, the earth and sand refers to solids such as gravel and sand mud collected together with the gas hydrate m from the bottom 2.

  Since it is difficult for sediment to accumulate in the gasification tank 5, the gas hydrate m is lifted up by the riser pipe 4 continuously for a long time, and in parallel with the gasification in the gasification tank 5, the discharge pipe 9 is used. The sediment can be discharged continuously. That is, the gas hydrate m can be collected continuously for a long time.

  In the present invention, the configuration for supplying the massive gas hydrate m to the gasification tank 5 is not limited to the riser pipe 4. What is necessary is just to have the structure which can supply the block-shaped gas hydrate m of the bottom 2 to the gasification tank 5, for example, you may comprise with a bucket etc.

  As illustrated in FIGS. 2 and 3, the gasification tank 5 is constituted by a horizontal tank in which the length in the vertical direction is set shorter than the length of the long side in the horizontal direction. In the figure, the flow direction of the slurry in the gasification tank 5 is indicated by an arrow x, the crossing direction intersecting the flow direction x in the horizontal plane is indicated by an arrow y, and the vertical direction is indicated by an arrow z. 2 and 3, the length of the gasification tank 5 in the flow direction x is a long side, and the length of the crossing direction y is a short side.

  The gasification tank 5 has a supply port 10 that guides the massive gas hydrate m together with the water in the bottom 2 to the inside of the gasification tank 5. The supply port 10 is formed at a position relatively above the side surface of the gasification tank 5. The supply port 10 is preferably formed at a position higher than the average water level WL of water in the gasification tank 5.

  A baffle plate 11 may be installed inside the gasification tank 5 and on an extension line of the supply port 10. The baffle plate 11 is installed at a position where the slurry and the gas hydrate m supplied from the supply port 10 into the gasification tank 5 can collide with each other.

  The gasification tank 5 has a gas recovery unit 7 that extracts the gas g inside the gasification tank 5 to the outside. The gas recovery unit 7 is formed on, for example, the upper surface of the gasification tank 5.

  The gasification tank 5 has a discharge port 12 through which water inside the gasification tank 5 and earth and sand accumulated at the bottom are discharged to the outside. The discharge port 12 is formed on the bottom surface of the gasification tank 5. A discharge pipe 9 is connected to the discharge port 12. The water level inside the gasification tank 5 may be adjusted by adjusting the flow rate of the water discharged from the discharge port 12.

  As illustrated in FIG. 2, the gasification tank 5 has a first inclined portion 13 formed on the bottom surface and inclined downward along the flow direction x. A discharge port 12 is disposed near the lower end of the first inclined portion 13. As illustrated in FIG. 3, the gasification tank 5 has a second inclined portion 14 formed on the side surface and inclined downward toward the discharge port 12 in the intersecting direction y.

  The 1st inclination part 13 and the 2nd inclination part 14 have the structure which makes it easy to guide to the discharge port 12, without depositing the earth and sand inside the gasification tank 5. FIG. In the present invention, the first inclined portion 13 and the second inclined portion 14 are not essential requirements. You may comprise in other shapes, such as the curved surface which curved the bottom face and side surface of the gasification tank 5. FIG.

  As illustrated in FIG. 2, a heating mechanism 15 that supplies heat to the gas hydrate m inside the gasification tank 5 may be installed in the gasification tank 5. In this embodiment, the heating mechanism 15 is formed on the side surface of the gasification tank 5, collects the water inside and takes it out to the outside, a heater 17 that heats the water collected at the water intake 16, And a nozzle portion 18 for supplying water heated by the heater 17 from the upper part in the gasification tank 5. You may install a pump in the middle of piping which connects the water intake 16 and the nozzle part 18. As shown in FIG.

  In this embodiment, the heater 17 is installed outside the gasification tank 5, but the present invention is not limited to this configuration. A heater 17 may be installed inside the gasification tank 5, and water recovered at the water intake 16 may be heated and supplied to the nozzle unit 18.

  In this specification, the upper part in the gasification tank 5 refers to a position inside the gasification tank 5 and above the average water level WL. The nozzle part 18 is installed in the gasification tank 5 at a position where it is not submerged.

  A screen 19 may be installed in the vicinity of the water intake 16 to prevent the inflow of solids such as a massive gas hydrate m. The screen 19 should just have the structure which allows water to pass through, preventing the passage of solid. For example, it can be composed of a wire mesh.

  The heater 17 is constituted by, for example, a heater that heats water that passes by supply of electricity, a heat exchanger that heats water that passes through a pipe by circulating surface water having a relatively high temperature as a heat medium, and the like. Can do. The configuration of the heater 17 is not limited to the above, and it is only necessary to have a configuration capable of heating the water collected at the water intake 16.

  The nozzle unit 18 has a configuration in which, for example, a plurality of openings are formed in the pipe and water heated from the openings is supplied from the upper side to the lower side in the gasification tank 5. The nozzle unit 18 may be configured to have only one opening. In this embodiment, a plurality of nozzle portions 18 are arranged inside the gasification tank 5 in a state of being spaced apart from each other along the flow direction. A flow control valve 20 is installed in each pipe from the heater 17 to each nozzle portion 18.

  The baffle plate may be installed on the extended line of the opening of the nozzle portion 18. The heated water supplied from the opening of the nozzle unit 18 falls on the water surface inside the gasification tank 5 in a state where the size of the liquid droplet collides with the baffle plate and becomes smaller. With this configuration, the movement in the vertical direction z of water inside the gasification tank 5 can be made relatively slow.

  By slowing the movement in the vertical direction z of water inside the gasification tank 5, the gas hydrate m in the water can easily float on the water surface. That is, the separation of the gas hydrate m due to the difference in specific gravity can be promoted. Specifically, in order to promote the rising of the gas hydrate m having a specific gravity of 0.91 and a diameter of 1 mm or more, it is desirable that the flow rate in the vertical direction z of the gasification tank 5 is 1 cm or less per second.

  The baffle plate disposed on the extended line of the opening of the nozzle portion 18 can be constituted by, for example, a flat plate, a perforated plate, a slat (louver), a wire mesh, or the like. When the nozzle part 18 has a plurality of openings, it is desirable to arrange the baffle plate in a state where heated water supplied from all the openings can collide with the baffle plate.

  The configuration of the heating mechanism 15 is not limited to the above. You may make it the structure which installs the heater 17 in the piping which reaches each nozzle part 18, respectively. That is, a configuration in which the temperature of water supplied to each nozzle unit 18 can be changed may be used. Moreover, it is good also considering the nozzle part 18 installed in the gasification tank 5 as one.

  A monitoring mechanism 21 that monitors the state of the massive gas hydrate m in the gasification tank 5 may be installed in the gasification tank 5. The monitoring mechanism 21 can be constituted by, for example, a camera installed inside the gasification tank 5 and an image processing machine that processes an image acquired by the camera. The monitoring mechanism 21 can measure the position, size, and distribution of the massive gas hydrate m floating in the water inside the gasification tank 5.

  The monitoring mechanism 21 is not limited to the above-described configuration, and may have a configuration capable of measuring the position and size of the gas hydrate m in the flow direction x and the cross direction y. The monitoring mechanism 21 is installed inside the gasification tank 5, for example, a laser scanner that measures the distance by irradiating laser light toward the gas hydrate m, an ultrasonic measurement device that measures the distance by ultrasonic waves, a gasification It can be configured by an X-ray device that is installed outside the tank 5 and measures the position of the gas hydrate m by X-rays.

  A control mechanism 22 that controls the flow rate control valve 20 may be installed in the gasification tank 5 in accordance with the state of the gas hydrate m obtained from the monitoring mechanism 21. By controlling the opening degree of the flow control valve 20, it is possible to increase the flow rate of hot water ejected from a certain nozzle unit 18 or to decrease the flow rate of hot water ejected from another nozzle unit.

  Further, the temperature of the hot water may be adjusted by the heater 17 according to the state of the gas hydrate m obtained from the monitoring mechanism 21. By controlling both the flow rate control valve 20 and the heater 17 according to the state of the gas hydrate m obtained from the monitoring mechanism 21, it is possible to control the flow rate and temperature of the hot water injected from the nozzle unit 18. it can. The control mechanism 22 is connected to the monitoring mechanism 21 and the flow rate control valve 20 via a wired or wireless signal line. In FIG. 2, the signal lines are indicated by alternate long and short dash lines for explanation.

  In the present invention, the monitoring mechanism 21 and the control mechanism 22 are not essential requirements. You may make it the structure which does not install the monitoring mechanism 21 and the control mechanism 22 in the gasification tank 5. FIG.

  The gasification tank 5 may be provided with a first injection mechanism 23 that is installed on the bottom surface of the gasification tank 5 and generates a water flow toward the discharge port 12. When the gasification tank 5 has the first inclined portion 13, the first injection mechanism 23 can be installed in the vicinity of the upper end of the first inclined portion 13. The 1st injection mechanism 23 should just have the structure which generate | occur | produces the water flow which the water to inject | pour toward the discharge port 12, and may be installed in the position moved upward from the bottom face of the gasification tank 5, for example. The number of the first injection mechanisms 23 installed in the gasification tank 5 may be one or plural.

  The gasification tank 5 may include a second injection mechanism 24 that generates a water flow in a direction opposite to the discharge port 12 in the vicinity of the discharge port 12 of the gasification tank 5. The second injection mechanism 24 can be installed on the bottom surface of the gasification tank 5 so as to generate a water flow upward, for example. The number of the second injection mechanisms 24 installed in the gasification tank 5 may be one or plural.

The 1st injection mechanism 23 and the 2nd injection mechanism 24 can inject the water collect | recovered from the water intake 16, for example. You may install a pump in the middle of piping which connects the 1st injection mechanism 23 and the 2nd injection mechanism 24, and the water intake port 16. FIG. The first injection mechanism 23 and the second injection mechanism 24 may be configured to take in surrounding water and inject it. 2 and 3, the water injection directions by the first injection mechanism 23 and the second injection mechanism are indicated by white arrows for the sake of explanation.

  The slurry pump 25 may be installed in the middle of the discharge pipe 9. The slurry pump 25 makes it easy to discharge the earth and sand inside the gasification tank 5 together with water. Water and earth and sand inside the gasification tank 5 can be returned to the bottom 2 through the discharge pipe 9. Since the water and earth and sand collected from the bottom 2 can be returned to the bottom 2, it is advantageous for suppressing changes in the underwater environment due to movement of earth and sand.

  When the gas hydrate m is recovered by the gas hydrate recovery device 1, first, slurry composed of water in the bottom 2, massive gas hydrate m and earth and sand is supplied into the gasification tank 5 from the supply port 10. (Supply process).

  When the baffle plate 11 is installed, the massive gas hydrate m collides with the baffle plate 11. By making it collide with the baffle plate 11, the massive gas hydrate m can be destroyed and reduced. Thereby, the gas hydrate m is easily melted.

  Further, by causing the slurry to collide with the baffle plate 11, the gas hydrate m spreads in the gasification tank 5, so that it is easily melted. The slurry collides with the baffle plate 11 and falls to the water surface inside the gasification tank 5 in a state where the size of the droplet is reduced. Therefore, the movement of water in the vertical direction z within the gasification tank 5 can be made relatively slow.

  The slurry supplied into the gasification tank 5 is separated by a difference in specific gravity (separation process). Since the gas hydrate m has a specific gravity smaller than that of water, it rises near the water surface. Inside the gasification tank 5, a flow is generated along the flow direction x by the supply of the slurry. Therefore, the gas hydrate m that has floated on the water surface easily gathers at a position far from the supply port 10. In FIG. 2, the gas hydrate m tends to gather on the right side of FIG.

  Since earth and sand have a specific gravity greater than that of water, they settle on the bottom of the gasification tank 5. When the gasification tank 5 includes at least one of the first inclined portion 13 and the second inclined portion 14, the earth and sand move toward the discharge port 12.

  Water in the gasification tank 5 is sent from the water intake 16 to the heater 17. The water heated by the heater 17 is jetted from the nozzle portion 18 to the gas hydrate m that floats on the water surface. The gas hydrate m is melted by heated water and decomposed into water and gas g (melting step).

  The gas hydrate m exists in a state of floating on the water surface in the gasification tank 5 and is melted by water supplied from above. Although water is taken from the water supplied from above and the water around the gas hydrate m as the gas hydrate m is melted, the water is taken from the intake port 16 located at a position lower than the gas hydrate m floating on the water surface. Is recovered, the water after the heat exchange with the gas hydrate m can be taken. That is, the heating mechanism 15 does not need to heat the entire amount of water in the gasification tank 5, and only circulates and uses only the surrounding water in which the gas hydrate m and the gas hydrate m exist. Therefore, the thermal efficiency at the time of melting the gas hydrate m can be improved.

  The heating mechanism 15 is configured to circulate water in the gasification tank 5 and does not use external water such as surface water. Therefore, it is possible to avoid mixing the surface water with the water at the bottom 2. This is advantageous for suppressing environmental changes in the bottom 2 such as the movement of microorganisms.

When the gas hydrate recovery device 1 has a plurality of nozzle portions 18 and a flow rate control valve 20, a position for supplying heated water in the gasification tank 5 under the control of the flow rate control valve 20. Can be adjusted. Since the gas hydrate m moves from the supply port 10 in the flow direction x, the amount of the gas hydrate m floating on the water surface increases as the position is farther from the supply port 10.

  Therefore, for example, it is possible to control the nozzle unit 18 installed at a position far from the supply port 10 along the flow direction x so that the amount of water to be ejected increases. Since the amount of heat supplied for each position in the flow direction x inside the gasification tank 5 can be adjusted, it is advantageous for efficiently melting the gas hydrate m.

  When the gas hydrate recovery device 1 includes the control mechanism 22, for example, the control mechanism 22 can perform control to change the amount of water ejected from each nozzle unit 18 every predetermined time. Moreover, you may make it the structure which adjusts the quantity of the water injected by the control mechanism 22 according to the excavation condition by the excavation mechanism 3 of the bottom 2.

  Specifically, when the amount of gas hydrate m recovered by the excavation mechanism 3 is not so large, the amount of water sprayed from the nozzle portion 18 is suppressed, and injection is performed as the amount of gas hydrate m to be recovered increases. Control to increase the amount of water to be performed may be performed. It is advantageous for improving the thermal efficiency in the gasification tank 5.

  When the gas hydrate recovery device 1 includes the monitoring mechanism 21, the flow rate of water supplied from the nozzle unit 18 is appropriately changed according to the distribution state of the gas hydrate m inside the gasification tank 5. be able to. That is, the distribution of the amount of heat to be supplied can be appropriately changed according to the distribution state of the gas hydrate m and the like. For example, it is possible to control to inject a large amount of heated water to a place where the amount of gas hydrate m floating on the water surface is large. It is further advantageous to efficiently melt the gas hydrate m.

  In the case where the gas hydrate recovery apparatus 1 includes a plurality of heaters 17 that are respectively disposed in the pipes that reach the nozzle portions 18, the temperature of the water supplied to each nozzle portion 18 can be changed as appropriate. Since the distribution of the amount of heat supplied to the inside of the gasification tank 5 can be controlled, the gas hydrate m can be efficiently melted. Both the flow rate and temperature of the water supplied from the nozzle unit 18 may be controlled, or one of them may be controlled.

  The gas g inside the gasification tank 5 is recovered from the gas recovery unit 7 (recovery process). The gas g includes, in addition to the gas g generated from the gas hydrate m that melts in the gasification tank 5, the gas g generated by melting the gas hydrate m in the middle of the riser pipe 4. In addition, the gas g dissolved in the water of the slurry is moved to the gas phase side with the passage of time inside the gasification tank 5.

  Sediment sedimented inside the gasification tank 5 is discharged to the outside from the discharge port 12 together with water (discharge process). For example, an opening / closing valve can be installed at the discharge port 12. Since the gasification tank 5 includes the discharge port 12, it is possible to avoid a problem that earth and sand accumulate in the gasification tank 5 and cause clogging. The earth and sand may be discharged continuously or intermittently. For example, the discharge port 12 can be switched between opening and closing every predetermined time.

  When the gasification tank 5 includes at least one of the first inclined portion 13 or the second inclined portion 14, the earth and sand moves to the vicinity of the discharge port 12 when depositing on the bottom of the gasification tank 5, The earth and sand can be efficiently discharged from the discharge port 12. It is advantageous for avoiding blockage due to earth and sand.

  When the gasification tank 5 includes the first injection mechanism 23, the sediment accumulated on the bottom surface can be forcibly moved to the discharge port 12 by injecting water from the first injection mechanism 23. The water injection by the first injection mechanism 23 may be performed continuously or intermittently. This is advantageous for suppressing sediment accumulation in the gasification tank 5. Since almost no cleaning or the like for removing earth and sand is required, the gas hydrate recovery device 1 can be operated continuously for a long time.

  In the case where the gasification tank 5 includes the second injection mechanism 24, the sediment accumulated near the discharge port 12 can be removed by injecting water from the second injection mechanism 24 (blocking prevention step). The water injection by the second injection mechanism 24 may be performed continuously or intermittently. It is advantageous to suppress the problem that the discharge port 12 is blocked by earth and sand.

  Further, when the water sprayed from the second spray mechanism 24 is sprayed upward, the slurry in the gasification tank 5 can be stirred. For example, the surrounding water can be cooled and re-frozen, and the gas hydrate m that has gathered together into a large lump can be crushed by stirring. Since the surface area of the gas hydrate m is increased by being finely crushed, it is advantageous for efficiently melting the gas hydrate m.

  You may make it the structure which controls the rotation direction of the slurry pump 25 installed in the discharge pipe 9 with the control mechanism 22. FIG. That is, the control mechanism 22 can be configured to switch between the normal rotation and the reverse rotation, which are the rotation directions of the slurry pump 25. When discharging the earth and sand, the slurry pump 25 is rotated forward, and the flow from the discharge port 12 toward the discharge pipe 9 is realized by the slurry pump 25 (forward rotation control).

  On the other hand, when the rotation direction of the slurry pump 25 is reversed, water flows from the discharge pipe 9 toward the gasification tank 5 (reverse rotation control). By this flow, similarly to the second injection mechanism 24, the earth and sand accumulated in the discharge port 12 can be removed, or the slurry in the gasification tank 5 can be stirred (blocking prevention step).

  You may make it the structure which installs in the gasification tank 5 the earth-and-sand monitoring mechanism 26 which monitors the state of the earth and sand in the inside of the gasification tank 5. FIG. The earth and sand monitoring mechanism 26 can be composed of, for example, a camera installed on the bottom surface of the gasification tank 5 and an image processor for processing images acquired by this camera. This earth and sand monitoring mechanism 26 can measure the position, amount and distribution of earth and sand accumulated on the bottom surface of the gasification tank 5.

  The earth and sand monitoring mechanism 26 is not limited to the above structure, and it is sufficient that the earth and sand monitoring mechanism 26 has a structure capable of measuring the amount of sediment deposited on the bottom surface of the gasification tank 5. The earth and sand monitoring mechanism 26 is installed on the bottom of the gasification tank 5, for example, a laser scanner for irradiating laser light toward the earth and sand to measure the distance, the position of the earth and sand by X-rays installed outside the gasification tank 5 and the like. X-ray equipment for measuring The earth and sand monitoring mechanism 26 may be shared with the monitoring mechanism 21 that measures the state of the gas hydrate m. That is, the monitoring mechanism 21 may measure both the gas hydrate m state and the earth and sand state.

  The gasification tank 5 is provided with a sediment control mechanism 27 for controlling the injection and stoppage of water of at least one of the first injection mechanism 23 and the second injection mechanism 24 according to the state of the sediment obtained from the sediment monitoring mechanism 26. You may make it the structure to carry out. For example, the sediment control mechanism 27 can inject water from the first injection mechanism 23 to positively move the sediment to the discharge port 12 when the sediment accumulation amount exceeds a predetermined value.

When sediment accumulation at the discharge port 12 is measured by the sediment monitoring mechanism 26, the sediment control mechanism 27 can eject water from the second injection mechanism 24 to remove the sediment in the vicinity of the discharge port 12. The control of the rotation direction of the slurry pump 25 may be controlled by the earth and sand control mechanism 27 according to the state of earth and sand obtained from the earth and sand monitoring mechanism 26.

  Since the first injection mechanism 23 and the like are controlled according to the state of the earth and sand, the earth and sand can be efficiently discharged from the inside of the gasification tank 5 to the outside. Moreover, it is advantageous to avoid the problem that the discharge port 12 is blocked by earth and sand.

  The earth and sand control mechanism 27 is connected to the earth and sand monitoring mechanism 26, the first injection mechanism 23, the second injection mechanism 24, and the slurry pump 25 via a wired or wireless signal line. In FIG. 2, the signal lines are indicated by alternate long and short dash lines for explanation.

  The earth and sand control mechanism 27 may be shared with the control mechanism 22. In other words, the control mechanism 22 may control the flow control valve 20 and the first injection mechanism 23 and the like.

  In the present invention, the sediment monitoring mechanism 26 and the sediment control mechanism 27 are not essential requirements. The gasification tank 5 may be configured such that the sediment monitoring mechanism 26 and the sediment control mechanism 27 are not installed.

  As illustrated in FIG. 4, a gravel dam plate 28 that prevents passage of gravel contained in earth and sand may be installed at the bottom of the gasification tank 5. The gravel blocking plate 28 is erected upward from the bottom of the gasification tank 5.

  In this embodiment, the gasification tank 5 includes a first discharge port 12 a that discharges gravel blocked by the gravel blocking plate 28 to the outside of the gasification tank 5, and the first discharge port 12 a and the discharge pipe 9. And a slurry pump 25a installed in the middle of the pipeline. A first inclined portion 13 that is inclined downward toward the first discharge port 12a is formed on the bottom surface located between the supply port 10 and the gravel blocking plate 28.

  The gasification tank 5 includes a second discharge port 12b for discharging sand mud passing through the gravel blocking plate 28 to the outside of the gasification tank 5 and a midway of a pipe line between the second discharge port 12b and the discharge pipe 9. And a slurry pump 25b installed in the vehicle. A first inclined portion 13 that is inclined downward toward the second discharge port 12b is formed on the bottom surface located between the gravel blocking plate 28 and the second discharge port 12b. The number of installed gravel stop plates 28 and outlets 12 is not limited to the above. A plurality of gravel blocking plates 28 and a plurality of discharge ports 12 may be installed in the gasification tank 5. When a plurality of discharge ports 12 are installed, a plurality of first inclined portions 13 that are inclined downward toward the respective discharge ports 12 may be formed.

  In this specification, gravel refers to crushed material having a particle size of 2 mm or more, and sand mud refers to crushed material having a particle size of less than 2 mm. Therefore, the gravel damming plate 28 can be constituted by, for example, a wire mesh having an opening of 2 mm. The size of the opening of the gravel blocking plate 28 can be changed as appropriate. For example, you may comprise a wire mesh with a 1 mm mesh.

  According to this configuration, gravel having a particle size of 2 mm or more is discharged from the first discharge port 12a (gravel processing step), and only sand mud having a particle size of less than 2 mm is discharged from the second discharge port 12b (sand). Mud treatment process). Since the properties of the respective slurries passing through the first discharge port 12a and the second discharge port 12b are stabilized, it becomes easy to optimize the slurry pumps 25a and 25b corresponding to the respective properties. It is advantageous for efficiently discharging earth and sand from the inside of the gasification tank 5. The gravel treatment step and the sand mud treatment step can be performed independently of each other.

By installing the gravel blocking plate 28, it is possible to suppress the occurrence of sloshing by suppressing the oscillation of water inside the gasification tank 5. With the suppression of sloshing, the movement of water in the vertical direction z in the gasification tank 5 can be made relatively slow. As a member that reinforces the strength of the gasification tank 5, a gravel blocking plate 28 can be used.

  You may make it the structure which installs the safety valve 29 which discharge | releases an internal gas outside when the pressure inside the gasification tank 5 becomes more than predetermined. The safety valve 29 can be installed on the upper surface of the gasification tank 5 or in the vicinity of the upper surface. Even when a problem occurs in which a large amount of gas together with the slurry is supplied into the gasification tank 5 from the supply port 10, the pressure inside the gasification tank 5 can be lowered by the safety valve 29. This is advantageous in avoiding damage to the gasification tank 5 and the like.

  The heating mechanism 15 may be constituted by a jacket 15 a installed on the outer peripheral surface of the gasification tank 5, for example. The slurry inside the gasification tank 5 can be heated by the jacket 15a. The jacket 15 a may be installed on the inner peripheral surface of the gasification tank 5. The heating mechanism 15 having the nozzle part 18 and the jacket 15a may be installed in combination. While the gas hydrate m is effectively melted by the heating mechanism 15 having the nozzle portion 18, the occurrence of a problem that the gas hydrate m adheres to the inner wall surface of the gasification tank 5 and grows ice by the jacket 15 a is suppressed. be able to.

  The jacket 15a can be configured to circulate a heat medium such as surface water. You may comprise the jacket 15a with the heater which heats up by supply of electricity.

  As illustrated in FIG. 5, the gasification tank 5 may be configured by a vertical tank in which the length in the vertical direction z is set longer than the length in the horizontal direction. In this embodiment, the upper part of the gasification tank 5 is formed in a cylindrical shape, and the lower part is formed in a truncated cone shape whose diameter decreases downward. According to this structure, since the whole bottom face of the gasification tank 5 is comprised by the inclination part, it is advantageous in suppressing sedimentation of earth and sand.

  Even when the gasification tank 5 is a vertical tank, the second injection mechanism 24 can be installed in the vicinity of the discharge port 12. This is advantageous for suppressing the blockage of the discharge pipe 9. In this embodiment, the two second injection mechanisms 24 are disposed on the bottom surface of the gasification tank 5 and in the vicinity of the discharge port 12.

  In this embodiment, a wave-dissipating plate 30 that prevents water from moving in the horizontal direction is disposed below the supply port 10. The wave-dissipating plate 30 can be configured by, for example, a plate-like member that extends in the vertical direction z and is combined in a lattice shape in plan view. The wave-dissipating plate 30 can pass water, such as a perforated plate or a wire mesh, but may have a structure that can reduce the impact of waves. Since the fluctuation of water inside the gasification tank 5 can be suppressed, even if the gasification tank 5 is installed in a ship that is likely to be shaken by waves, the specific gravity difference between the gas hydrate m and earth and sand. Can be stably performed. Further, the strength of the gasification tank 5 that is a relatively large structure can be reinforced by the wave-dissipating plate 30.

  The average water level WL is maintained in a state above the upper end of the wave absorbing plate 30. Therefore, the gas hydrate m floating in the water flows and gathers at a position away from the supply port 10. One nozzle portion 18 is disposed above the position where the gas hydrate m gathers. You may make it the structure by which this nozzle part 18 is arranged in multiple numbers.

  When taking out the gas g from the gas recovery unit 7, it is desirable to maintain the internal pressure of the gasification tank 5 higher than the external pressure (atmospheric pressure). It is advantageous to prevent the quality of the gas g from becoming unstable due to the atmosphere flowing into the gasification tank 5 and mixing air or the like with the gas g.

  As illustrated in FIG. 6, the gasification tank 5 may be composed of two vertical tanks. In this embodiment, the gasification tank 5 is composed of a tank constituting the separation part 5a and a tank constituting the melting part 5b. Separation part 5a has supply port 10 to which slurry is supplied and discharge port 12 for discharging earth and sand to the outside. A wave-dissipating plate 30 may be installed in the separation unit 5a.

  The melting part 5 b has a water intake 16, a heater 17, and a nozzle part 18 that constitute the heating mechanism 15. On the upper surface of the melting part 5b, a gas recovery part 7 for taking out the gas g generated inside is disposed. The melting part 5b may have a discharge port 12 on the bottom surface for precipitating the earth and sand that could not be separated by the separation part 5a and discharging it to the outside. Even when recovery of the gas hydrate m from the bottom 2 is interrupted for a short time, in order to continuously supply the gas g to the gas supply line 8, the gas hydrate m is melted to a size that can store a predetermined amount or more. The part 5b may be configured. That is, the melting part 5b may have a function of storing the gas hydrate m. In the embodiment of FIG. 6, the second injection mechanism 24 may be installed in the vicinity of each discharge port 12 of the separation unit 5 a and the melting unit 5 b.

  An overflow pipe 31 is disposed between the separation part 5a and the melting part 5b. One end of the overflow pipe 31 is connected in the vicinity of the average water level WL of the separation part 5a, and the other end is connected above the average water level WL of the melting part 5b. The overflow pipe 31 is arranged in a state where the end on the separation part 5a side is higher than the end on the melting part 5b side, and the gas hydrate m is melted by the overflow in the separation part 5a. It has the structure which flows into the part 5b. For example, the water levels of the separation unit 5a and the melting unit 5b may be adjusted by adjusting the flow rates of water discharged from the discharge ports 12 of the separation unit 5a and the melting unit 5b.

  The separation unit 5a has a configuration in which the slurry supplied from the supply port 10 is separated by a specific gravity difference. The gas hydrate m that floats on the water surface in the separation unit 5a moves with the water to the melting unit 5b via the overflow pipe 31. Due to the flow of the slurry supplied from the supply port 10, the gas hydrate m moves from the separation unit 5 a to the overflow pipe 31.

  The gas hydrate m may be mechanically moved from the separation unit 5a to the overflow pipe 31 by a scraper or the like. Also in the separation unit 5a, the gas g dissolved in the slurry and the gas g generated by the melting of the gas hydrate m are accumulated in the upper part, so it is desirable to form the gas recovery unit 7 on the upper surface.

  The water that moves to the melting portion 5b together with the gas hydrate m is recovered from the water intake port 16, heated, and sprayed from the nozzle portion 18 to the gas hydrate m. You may install a pump in the middle of piping which connects the water intake 16 and the nozzle part 18. As shown in FIG.

  Since the melting part 5b is composed of a tank different from the separation part 5a, the heat of water supplied from the nozzle part 18 does not move to the slurry of the separation part 5a. It is advantageous to efficiently apply the heat supplied from the heating mechanism 15 to the gas hydrate m.

An isolation wall extending in the vertical direction may be arranged inside one gasification tank 5 to separate the separation portion 5a and the melting portion 5b. In this case, an opening for moving the gas hydrate m from the separation part 5a to the melting part 5b can be formed in the isolation wall. Further, by arranging the discharge ports 12 on the bottom surfaces of the separation unit 5a and the melting unit 5b, and adjusting the flow rate of the water discharged from each discharge port 12, the water level between the separation unit 5a and the melting unit 5b is adjusted. You may make it the structure to carry out. With this configuration, the water level of the separation part 5a is raised and overflowed from the upper part of the isolation wall to the melting part 5b, and the gas hydrate m can be moved to the melting part 5b.

DESCRIPTION OF SYMBOLS 1 Gas hydrate collection | recovery apparatus 2 Water bottom 3 Excavation mechanism 4 Riser pipe 4a Recovery port 5 Gasification tank 5a Separation part 5b Melting part 6 Structure 7 Gas recovery part 8 Gas supply line 9 Discharge pipe 9a Lower end part 10 Supply port 11 Baffle plate DESCRIPTION OF SYMBOLS 12 Discharge port 12a 1st discharge port 12b 2nd discharge port 13 1st inclination part 14 2nd inclination part 15 Heating mechanism 15a Jacket 16 Water intake 17 Heater 18 Nozzle part 19 Screen 20 Flow control valve 21 Monitoring mechanism 22 Control mechanism 23 First injection mechanism 24 Second injection mechanism 25 Slurry pump 25a Slurry pump 25b Slurry pump 26 Sediment monitoring mechanism 27 Sediment control mechanism 28 Gravel dam plate 29 Safety valve 30 Wave extinguishing plate 31 Overflow pipe m Gas hydrate g Gas x Flow direction y Crossing Direction z Vertical direction WL Average water level

Claims (12)

In a gas hydrate recovery apparatus comprising a gasification tank for recovering a massive gas hydrate collected from the water bottom together with water at the bottom of the water,
The gasification tank includes a supply port that guides the gas hydrate in a lump together with the water in the bottom of the gasification tank, a gas recovery unit that extracts the gas in the gasification tank to the outside, and the gasification A gas hydrate recovery device, comprising: a discharge port that is disposed at the bottom of the tank and discharges the earth and sand recovered together with the water in the bottom. A heating mechanism for supplying heat to the massive gas hydrate in the gasification tank;
The heating mechanism has a water intake port for collecting water in the gasification tank, a heater for heating water recovered from the water intake port, and water heated by the heater in the gasification tank. The gas hydrate collection | recovery apparatus of Claim 1 provided with the nozzle part supplied from upper part.   The heating mechanism has a plurality of nozzle portions arranged in the gasification tank at intervals, and a flow rate of water supplied to the nozzle portions respectively installed in the plurality of nozzle portions. The gas hydrate collection | recovery apparatus of Claim 2 provided with the flow control valve to control.   A monitoring mechanism for monitoring the state of the massive gas hydrate inside the gasification tank, and a control mechanism for controlling the plurality of flow rate control valves according to the state of the massive gas hydrate obtained from the monitoring mechanism A gas hydrate recovery device according to claim 3.   The gasification tank has the supply port and the discharge port, and includes a separation unit that separates the gas hydrate in a lump form from the water at the bottom of the water, and the water intake port and the nozzle unit that constitute the heating mechanism. A gas hydrate recovery device according to any one of claims 2 to 4, further comprising a melting portion to which the gas hydrate in a lump shape separated by the separation portion is supplied.   The gas hydrate collection | recovery apparatus in any one of Claims 1-5 provided with the baffle board which is arrange | positioned inside the said gasification tank and collides with the said block-shaped gas hydrate supplied from the said supply port. A riser pipe extending from the gasification tank toward the bottom of the water and collecting the massive gas hydrate collected at the bottom of the water together with the water of the bottom of the water, and a gas recovered from the gasification tank of the riser pipe A gas lift mechanism to supply inside,
The gas hydrate recovery apparatus according to claim 1, wherein the gas lift mechanism is configured to supply the gas to a position in the middle of the riser pipe where the water depth is 300 m or less. In the gas recovery method for recovering the gas generated by melting the massive gas hydrate by recovering the massive gas hydrate from the bottom with the water in the bottom to a gasification tank,
A supply step of supplying the massive gas hydrate and earth and sand together with the water in the bottom into the gasification tank;
A separation step of separating the massive gas hydrate and the earth and sand by a specific gravity difference;
A melting step of melting the massive gas hydrate to generate gas;
A recovery step of taking out and recovering the gas inside the gasification tank to the outside;
A gas recovery method comprising: a discharge step of discharging the earth and sand separated in the separation step to the outside of the gasification tank. The gas recovery method according to claim 8, wherein in the melting step, water in the gasification tank is taken, and the water is heated and then supplied from an upper part in the gasification tank. Installing a plurality of nozzle parts for supplying water heated from the gasification tank from the upper part of the gasification tank;
The melting step monitors the state of the gas hydrate in the gasification tank and controls the flow rate of the water supplied from each nozzle unit according to the state of the gas hydrate. The gas recovery method according to claim 9. Forming a separation part and a melting part in the gasification tank
Separating the massive gas hydrate and the earth and sand in the separation unit, discharging the earth and sand to the outside of the gasification tank and supplying the massive gas hydrate to the melting part;
The gas recovery method according to any one of claims 8 to 10, wherein the gas generated is recovered while melting the massive gas hydrate in the melting part.   The mass gas hydrate collides with a baffle plate disposed inside the gasification tank when the mass gas hydrate and the earth and sand are supplied into the gasification tank together with water in the bottom of the water. Item 12. The gas recovery method according to any one of Items 8 to 11.

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