JPWO2003006589A1 - Granulation, handling and transportation of gas hydrate - Google Patents

Abstract

The powdery gas hydrate is compression-molded by a granulator to form a pellet. Thereafter, the solidified gas hydrate is loaded into tanks of ships and storage facilities.

Description

TECHNICAL FIELD The present invention relates to a method for granulating, loading, and transporting a so-called gas hydrate composed of a gas mainly composed of methane, such as natural gas, and water, and to a method for transporting and granulating gas hydrate.
BACKGROUND ART Conventionally, transportation and storage of natural gas have been performed in the form of liquefied natural gas (hereinafter, referred to as LNG) or compressed natural gas.
However, LNG needs to be transported and stored while maintaining the cargo temperature at minus 162 ° C, and requires special vessels (LNG vessels) and storage facilities with expensive tanks specially manufactured for transport and storage. It is. Further, in order to make the liquid of minus 162 ° C., it is necessary to put a lot of energy into the production. In addition, LNG vaporizes rapidly when control goes wrong, and is dangerous. In addition, LNG has an extremely low temperature, as described above, and therefore has a high vaporization rate and is not suitable for long-term storage.
On the other hand, methane-based gas, such as natural gas, is attracting attention as a clean energy source and raw material for various structures, and natural gas, such as natural gas, is artificially used for transportation and storage. In addition, research on making gas hydrate industrially has been conducted.
Gas hydrate has a crystal structure in which gas molecules are contained one by one in a basket formed by water molecules. For example, in methane hydrate, 1 m ³ of methane hydrate at normal pressure (this It is said that 164 m ³ of methane can be stored in 0.8 m ³ of water.
Thus, methane hydrate has attracted attention as a new natural gas transport and storage alternative to LNG because of its high gas storage capacity. The density of methane gas in methane hydrate is about 3.5 times lower than that of LNG, but when manufactured artificially or industrially, it is cooled down to the liquefaction temperature (less than -162 ° C) like LNG. It is said that energy efficiency is greatly improved because there is no need.
When methane hydrate is artificially produced, for example, water or an antifreeze is sprayed from a spraying means into a pressure vessel having a temperature of 1 to 10 ° C. and a pressure of 30 to 100 atm. Supply gas (methane). Then, the water or antifreeze sprayed from the spraying means and natural gas (methane) are synthesized to generate powdery methane hydrate. Since the powdered methane hydrate has a small filling rate (volume of methane hydrate / volume of the storage container), a tank having a large volume is required for transportation and storage.
Further, when stored in large quantities for a long period of time, powdery gas hydrates have a problem in that they are combined with each other due to their own weight and the like to form a rock, and are difficult to take out (unload).
DISCLOSURE OF THE INVENTION The present invention has been made in view of such conventional problems, and aims at improving the filling rate of gas hydrate, safety during transportation and storage, handling during cargo handling. It is an object of the present invention to provide a method of granulating and handling gas hydrate, and a method of transporting the gas hydrate, which can measure the ease and the like of the gas hydrate.
In order to solve the above-mentioned problems, a gas hydrate granulation method of the present invention is characterized in that a powdery gas hydrate is compression-molded by a granulator to form a pellet.
Further, the gas hydrate loading method of the present invention is a method of compressing and molding a powdery gas hydrate into a pellet by a granulator, and thereafter, the solidified gas hydrate is stored in a tank of a ship or a storage facility. It is characterized by loading.
Here, before processing the powdery gas hydrate into pellets, it is preferable to spray a liquid on the gas hydrate in advance to wet it. Further, it is preferable to spray a liquid onto the solidified gas hydrate to moisten it, and then to supercool it. Further, it is preferable to mix two or more kinds of gas hydrates in the form of pellets having different dimensions and load the mixed gas hydrate on a ship or a storage tank of a storage facility. Further, it is preferable that the diameter ratio of two or more kinds of gas hydrates in the form of pellets having different dimensions is 1.5 to 30.
On the other hand, the method for transporting gas hydrate of the present invention comprises compressing powdery gas hydrate by a granulator into pellets, and then solidifying the gaseous hydrate in a tank of a ship or storage facility. It is loaded and transported at a predetermined temperature.
Here, it is preferable to maintain the storage temperature of the gas hydrate in the form of pellets at -5 ° C to -30 ° C.
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view showing a gas hydrate granulation and cargo handling method according to the present invention. Before describing the method, a method for artificially producing methane hydrate will be briefly described.
Methane hydrate can be produced by two methods, a dry method and a wet method, and when it is produced by a wet method, for example, it is produced by an apparatus shown in FIG.
This apparatus comprises a cylindrical container 101, the temperature in the container 101 is maintained at 1 to 10 ° C, and the pressure is maintained at 30 to 100 atm. The water or antifreeze sprayed from the spraying means 112 is combined with natural gas (methane) supplied from the supply pipe 108 in the reaction section 101A to generate powdery methane hydrate a, and the water or antifreeze in the storage section 101B is formed. Fall to the surface of antifreeze. The powdery methane hydrate a floating on the surface layer of water or antifreeze is sequentially drawn by the scraper 114 toward the discharge port 107 and discharged from the discharge port 107. The powdery methane hydrate a discharged from the discharge port 107 is stored in a storage tank (not shown) after removing excess water or antifreeze.
In the drawing, 103 is a cooling jacket, 106 is a refrigerant supply line, 102 is a refrigerant outlet line, 104 is a water or antifreeze draining line, 105 is a water or antifreeze circulation line, 110 is a circulation pump, 111 is water or An antifreeze extraction line 113 is a water or antifreeze supply line.
Next, the method for granulating and handling gas hydrate according to the present invention will be described with reference to FIG.
In FIG. 1, 1 is a storage tank for storing powdered methane hydrate a, 2 is a horizontal screw conveyor provided at the bottom of the storage tank 1, and the screw conveyor 2 is a cylindrical main body 3. And a screw shaft 4 positively driven by an electric motor 5. The main body 2 has a downwardly directed duct 6 on the lower surface of the distal end.
Immediately below the duct 6, a pelletizer (granulator) 7 including two rollers 8a and 8b is provided. The roller 8a rotates clockwise in the figure, and the roller 8b rotates counterclockwise in synchronization with the roller 8a.
As shown in FIG. 2, hemispherical depressions 9 are provided at regular intervals in the circumferential direction on the outer peripheral surfaces of the rollers 8a and 8b. The shape of the depression 9 is not limited to a hemisphere, and a desired shape such as a semi-elliptical sphere or a semi-column is employed. The size is also set to an arbitrary size. Note that the pelletizer is not limited to the above-described roller system, and other systems may be used.
Returning to FIG. 1, a water injection nozzle 10 is provided between the duct 6 and the pelletizer 7. Further, a horizontal transfer device 11 is provided directly below the pelletizer 7. The transport device 11 includes a belt conveyor 12 and a box-shaped main body 13. The main body 13 has a hopper 14 directly below the pelletizer 7 and a downward duct 15 on the lower surface of the tip. Further, the main body 13 of the transport device 11 is provided with a water injection nozzle 10 a on the downstream side of the hopper 14. The water injection nozzle 10 a has its tip directed toward the upper surface of the belt conveyor 12.
Further, the main body 13 has a cooling jacket (not shown) on the outside thereof, so that the conveyed object conveyed by the belt conveyor 12 is supercooled. Further, the belt conveyor 12 is held by two to three rollers 16 at one location so as to maintain the dynamic angle of repose (see FIG. 3).
The space between the duct 6 of the screw conveyor 2 and the hopper 14 of the transfer device 11 is sealed with a cover or the like (not shown) so that vaporized gas does not leak to the outside.
Next, a case where methane hydrate (NGH) is loaded and transported on a carrier (bulk carrier) will be described.
As shown in FIG. 1, when the duct 15 of the transport device 11 is inserted into the loading port 32 of the hold (loading tank) 31 of the bulk carrier 30 and then the electric motor 5 of the screw conveyor 2 is driven, the storage tank 1 is supplied to the pelletizer 7 by the horizontal screw conveyor 2.
The powdery methane hydrate a supplied to the pelletizer 7 is compression-molded by two rollers 8a and 8b having a hemispherical depression 9 on the outer peripheral surface, and is formed into a spherical (ball-shaped) methane hydrate b. You. When the wetness of the powdery methane hydrate a is insufficient, water c is injected from the water injection nozzle 10 to wet the powdery methane hydrate a. Then, the tightness of the powdery methane hydrate a becomes hard, and the powder methane hydrate a hardly breaks even when dropped.
The ball-shaped methane hydrate (hereinafter, referred to as methane hydrate ball) b is supplied from the pelletizer 7 onto the belt conveyor 12 of the transport device 11, for example, in a hold of a large carrier (bulk carrier) 30. In the case of loading into the cargo tank 31, water c is sprayed from a water spray nozzle 10 a provided on the main body 13 of the transfer device 11 toward the methane hydrate ball b on the belt conveyor 12 to decrease the temperature from −5 ° C. to −20 ° C. To supercool.
Then, the outer surface of the methane hydrate ball b is covered with an ice film (capsule), the strength of the methane hydrate ball b further increases, and the methane hydrate ball b is held in the hold (load tank) 31 of the large carrier (bulk carrier) 30. Not only will it be hard to break even when loaded, but it will be less likely to be crushed by its weight even when loaded in large quantities.
Powdered gas hydrate a has a self-preserving property because it has a crystal structure in which gas molecules are contained one by one in a basket formed by water molecules. In addition, when the outer surface of the methane hydrate ball b is covered with an ice film (capsule), there is an advantage that the self-preservation property is further improved.
The methane hydrate ball b whose outer surface is covered with the ice film is loaded into the hold (load tank) 31 of the bulk carrier 30 by the belt conveyor 12. The inside of the hold (load tank) 31 is maintained at a lower temperature (for example, minus 5 ° C. to minus 30 ° C.) than the temperature at which the methane hydrate ball b decomposes.
As the bulk carriers 30, those shown in FIGS. 7 and 8 are preferably used. The bulk carrier 30 shown in FIG. 7 has a loading conveyor 33 and a discharging conveyor 35. Further, a baffle plate / hatch 38 for evenly loading the gas hydrate balls b is provided. The baffle plate / hatch 38 moves up and down. In the figure, 31 is a hold, 34 is a gate, 36 is a ballast tank, 37 is a cover, and 39 is a heat insulating material.
On the other hand, the bulk carrier 30 shown in FIG. 8 includes a cargo handling machine 50 that can move in the bow and stern direction. Reference numeral 31 denotes a hold, 37 denotes a cover, and 39 denotes a heat insulating material.
In the above description, the case where the methane hydrate balls b are loaded into the hold (load tank) 31 by the belt conveyor type transfer device 11 is described. However, when the methane hydrate balls b are directly loaded from the pelletizer 7 into the hold (load tank) 31, the transfer is performed. A pneumatic transportation system may be adopted as the device.
Also, when the methane hydrate balls b are loaded on the tank lorry 40, the methane hydrate balls b are loaded on the tank 41 of the tank lorry 40 by the belt-conveyor-type transfer device 11 similarly to the ship (see FIG. 6). Also, when the methane hydrate balls b are stored in the storage facility, the methane hydrate balls b are transported by the belt conveyor type transport device 11 as in the case of the tank lorry.
The size of the methane hydrate ball b may be from several centimeters to several tens centimeters, and sometimes about several meters. The larger the ratio, the smaller the surface area ratio and the less bridging occurs, resulting in a higher filling factor. The filling rate of the methane hydrate balls b granulated as described above is about 60%. Incidentally, since the filling rate of the powdery gas hydrate is 40%, it can be seen that the filling rate is greatly improved by granulating the gas hydrate.
FIG. 5 shows a method for further improving the filling rate of methane hydrate balls. That is, this is a method in which a pelletizer 7 'for producing methane hydrate balls b' having a large particle diameter and a pelletizer 7 "for producing methane hydrate balls b" having a small particle diameter. According to this method, the space (1-filling rate) created by the large methane hydrate balls b ′ is to be filled with methane hydrate balls b ″ having small particles. The rate filling rate is further improved to about 80%.
What is important here is the ratio of the diameter of the large methane hydrate ball b ′ to the diameter of the small methane hydrate ball b ″ (diameter ratio = the diameter of the large methane hydrate ball / the small methane hydrate ball). According to experiments, the diameter ratio is preferably in the range of 1.5 to 30, more preferably 5 to 20.
When the diameter ratio is less than 1.5, the filling rate does not increase because the small methane hydrate balls b ″ do not enter the space of the large methane hydrate balls b ′.
On the other hand, if the diameter ratio exceeds 30, the number of small methane hydrate balls b ″ increases and bridges are easily generated, so that the filling rate does not increase. Refers to the diameter of the inscribed sphere.
If this method is employed, the size of the hold (load tank) or tank lorry will be reduced to half or less as compared with the case where powder methane hydrate a is loaded. Further, the number of types of methane hydrate balls is preferably two or more. For example, when three types of methane hydrate balls, large, medium and small, are used, the filling rate can be further improved.
As described above, if the present invention is adopted and the temperature is kept lower than the temperature at which the methane hydrate ball decomposes, the contact area between adjacent methane hydrate balls is small, so that the methane hydrate balls are in a sintered state. To maintain.
Therefore, the aggregate of methane hydrate balls to be transported can be easily pulverized, and can be unloaded with a glove or the like.
In the above description, the case where methane hydrate balls are loaded in a hold or a tank truck is described. However, the present invention can also be applied to a case where methane hydrate balls are stored in a tank of a storage facility.
The present invention is also applicable to granulation, cargo handling, storage and transportation of gas hydrates other than methane such as propane and carbon dioxide.
As described above, according to the present invention, the gas hydrate can be made into a solid having uniform shape and quality by industrially pelletizing the powdery gas hydrate. For this reason, the fluidity of the gas hydrate is dramatically increased, and cargo handling and transportation are facilitated.
Further, the present invention is to industrially pelletize the powdery gas hydrate, so that the filling rate is significantly improved as compared with the powdery gas hydrate, and the transportation and storage can be ensured economically. became.
In addition, gas hydrate has a crystal structure in which gas molecules are contained one by one in a basket made by water molecules, so it does not vaporize rapidly even if the temperature control is malfunctioning, Higher safety than LNG. Also, since the vaporization rate is slow, it is more suitable for long-term storage than LNG.
Further, since the ball-shaped gas hydrate has a small contact area, the ball-shaped gas hydrate maintains a sintered state. Therefore, the aggregate of the ball-shaped gas hydrates collected during transportation or storage can be easily pulverized, and can be easily unloaded using, for example, a glove.
In addition, in the present invention, an ice film (capsule) is formed on the surface of the ball-shaped gas hydrate by spraying water on the ball-shaped gas hydrate and supercooling the ball-shaped gas hydrate, thereby reducing the strength of the ball-shaped gas hydrate. It increases and becomes hard to break. For this reason, a large amount of transportation and storage become possible.
Further, in the present invention, since two or more types of ball-shaped gas hydrates having different dimensions are mixed and loaded, the filling rate is further improved as compared with a case where only ball-shaped gas hydrates having the same diameter are loaded. Can be.
INDUSTRIAL APPLICABILITY The present invention having the above-mentioned excellent effects can be very effectively used for granulation, cargo handling and transportation of gas hydrate.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a method for granulating and loading gas hydrate according to the present invention.
FIG. 2 is an enlarged front view including a partial cross section of the pelletizer.
FIG. 3 is a cross-sectional view of the transfer device.
FIG. 4 is an explanatory view of a gas hydrate production method.
FIG. 5 is an explanatory diagram in the case of mixing two types of gas hydrates, large and small.
FIG. 6 is an explanatory view in the case of loading on a tank lorry.
FIG. 7 is a sectional view of the carrier.
FIG. 8 is a sectional view showing another example of the carrier.

[0001]
TECHNICAL FIELD The present invention relates to a method of handling a gas hydrate that handles a so-called gas hydrate composed of a gas mainly composed of methane, such as natural gas, and water, such as natural gas.
BACKGROUND ART Conventionally, transportation and storage of natural gas have been performed in the form of liquefied natural gas (hereinafter, referred to as LNG) or compressed natural gas.
However, LNG needs to be transported and stored while keeping the cargo temperature at minus 162 ° C, and requires special vessels (LNG vessels) and storage facilities with expensive tanks specially created for transport and storage. It is. Further, in order to make the liquid of minus 162 ° C., it is necessary to put a lot of energy into the production. In addition, LNG vaporizes rapidly when control goes wrong, and is dangerous. Further, as described above, LNG has an extremely low temperature and therefore has a high vaporization rate and is not suitable for a long-term storage tank.
On the other hand, methane-based gas, such as natural gas, is attracting attention as a clean energy source and raw material for various structures. For transportation and storage, natural gas-based gas, such as natural gas, is artificially used. Or industrially

[0003]
Therefore, a tank having a large capacity is required.
Further, when stored in large quantities for a long period of time, powdery gas hydrates have a problem in that they are combined with each other due to their own weight and the like to form a rock, and are difficult to take out (unload).
DISCLOSURE OF THE INVENTION The present invention has been made in view of such conventional problems, and aims at improving the filling rate of gas hydrate, safety during transportation and storage, handling during cargo handling. An object of the present invention is to provide a gas hydrate loading and unloading method capable of measuring the ease of loading and the like.
In order to solve the above problems, the gas hydrate loading and unloading method of the present invention comprises compressing a powdery gas hydrate with a granulating device into pellets, and thereafter, transporting the pelletized gas hydrate to a ship. And a method for loading and unloading gas hydrates in a storage tank of a storage facility, wherein two or more types of gas hydrates in the form of pellets having different dimensions are mixed and loaded in the storage tank.
Here, before processing the powdery gas hydrate into pellets, it is preferable to spray a liquid on the powdery gas hydrate to wet it.
Further, it is preferable that the diameter ratio of two or more kinds of gas hydrates in the form of pellets having different dimensions is 1.5 to 30.

[0004]
New
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing a method for handling gas hydrate according to the present invention.
FIG. 2 is an enlarged front view including a partial cross section of the pelletizer.
FIG. 3 is a cross-sectional view of the transfer device.
FIG. 4 is an explanatory view of a gas hydrate production method.
FIG. 5 is an explanatory diagram in the case of mixing two types of gas hydrates, large and small.

[0005]
FIG. 6 is an explanatory view in the case of loading on a tank lorry.
FIG. 7 is a sectional view of the carrier.
FIG. 8 is a sectional view showing another example of the carrier.
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanation showing a method for cargo handling of gas hydrate according to the present invention. Before explaining the method, a method for artificially producing methane hydrate will be briefly described.
Methane hydrate can be produced by two methods, a dry method and a wet method, and when it is produced by a wet method, for example, it is produced by an apparatus shown in FIG.
This apparatus comprises a cylindrical container 101, the temperature in the container 101 is maintained at 1 to 10 ° C, and the pressure is maintained at 30 to 100 atm. The water or antifreeze sprayed from the spraying means 112 is combined with natural gas (methane) supplied from the supply pipe 108 in the reaction section 101A to generate powdery methane hydrate a, and the water or antifreeze in the storage section 101B is formed. Fall to the surface of antifreeze. The powdery methane hydrate a floating on the surface layer of water or antifreeze is discharged by the scraper 114 in order.

[0006]
It is drawn to the direction 107 and discharged from the discharge port 107. The powdery methane hydrate a discharged from the discharge port 107 is stored in a storage tank (not shown) after removing excess water or antifreeze.
In the drawing, 103 is a cooling jacket, 106 is a refrigerant supply line, 102 is a refrigerant outlet line, 104 is a water or antifreeze draining line, 105 is a water or antifreeze circulation line, 110 is a circulation pump, 111 is water or An antifreeze extraction line 113 is a water or antifreeze supply line.
Next, a method for loading and unloading gas hydrate according to the present invention will be described with reference to FIG.
In FIG. 1, 1 is a storage tank for storing powdered methane hydrate a, 2 is a horizontal screw conveyor provided at the bottom of the storage tank 1, and the screw conveyor 2 is a cylindrical main body 3. And a screw shaft 4 positively driven by an electric motor 5. The main body 2 has a downwardly directed duct 6 on the lower surface of the distal end.
Immediately below the duct 6, a pelletizer (granulator) 7 including two rollers 8a and 8b is provided. The roller 8a rotates clockwise in the figure, and the roller 8b rotates counterclockwise in synchronization with the roller 8a.

Claims (8)

A method for granulating gas hydrate, wherein a powdery gas hydrate is compression-molded into a pellet by a granulator. A method for loading and unloading a gas hydrate, comprising compressing a powdery gas hydrate with a granulator to form a pellet, and thereafter loading the solidified gas hydrate in a storage tank of a ship or a storage facility. 3. The gas hydrate handling method according to claim 2, wherein a liquid is sprayed on the gas hydrate to wet it before the powdery gas hydrate is processed into pellets. 3. The method for handling gas hydrate according to claim 2, wherein the solidified gas hydrate is sprayed with a liquid to moisten the liquid and then supercooled. The method for handling gas hydrate according to any one of claims 2 to 4, wherein two or more kinds of gas hydrates in pellets having different dimensions are mixed and loaded into a tank of a ship or a storage facility. 6. The method for handling gas hydrate according to claim 5, wherein the diameter ratio of the gas hydrate in the form of two or more pellets having different dimensions is 1.5 to 30. The powdered gas hydrate is compression-molded by a granulator into pellets, and then the solidified gas hydrate is loaded into a tank of a ship or storage facility and transported at a predetermined temperature. Gas hydrate transportation method. The method for transporting gas hydrate according to claim 7, wherein the storage temperature of the gas hydrate in the form of pellets is maintained at -5C to -30C.

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