JP2000302702A - Production of gas hydrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for continuously producing methane hydrate in an industrial scale suitable for transportation or the like from a natural gas mainly comprising methane and water. SOLUTION: This method comprises supplying a raw gas mainly comprising methane and water or an anti-freeze into the first pressure vessel, producing fine crystals of methane hydrate with a high speed agitation by a rotating agitator, supplying the raw gas and water or the anti-freeze to the second pressure vessel, producing crystals of methane hydrate having diameter larger than the prescribed crystals with a slower speed agitation than the prescribed agitating speed by an agitator, discharging the methane hydrate crystals to the outside after mixing both methane hydrate crystals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing gas hydrate, and more particularly, to industrially produce methane hydrate (or gas hydrate) from water containing methane as a main component such as natural gas and water. It relates to a gas hydrate production method.

[0002]

2. Description of the Related Art In recent years, natural gas and other gases mainly containing methane have attracted attention as a clean energy source and various constituent materials, and research has been conducted to convert natural gas into a gas hydrate for the purpose of storage or transportation. Has been done. Methane hydrate is composed of water and methane, and its production requires a high pressure of, for example, about 80 MPa or more at a temperature of 303 ° K. And methane hydrate
It is a structurally unstable substance. For example, the water / methane ratio (hydration number) of methane hydrate is determined by the occupancy rate of gas molecules with respect to the structure at the molecular level (theoretically, the hydration number is 1 On the other hand, the water molecule has an apparent hydration number of 5.75) and a water / methane ratio including macro unbound water. Conventionally, methane hydrate is a method in which methane and water are reacted under high pressure and low temperature using a pressure vessel, but this method is only a laboratory method and is manufactured continuously in an industrial manner. There was no known way to do it.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to continuously and industrially produce methane hydrate suitable for transportation and the like from a gas containing methane as a main component such as water and natural gas. It is an object of the present invention to provide a manufacturing method which can be used.

[0004]

Means for Solving the Problems To solve the above problems, the invention claimed in the present application is as follows. (1) A raw material gas containing methane as a main component and water or an antifreeze are supplied to a first pressure vessel, and high-speed stirring is performed by a rotary stirrer to generate methane hydrate microcrystals. And water or an antifreeze solution are supplied to the second pressure vessel, and the same stirrer is used to stir at a lower stirring speed than the aforementioned stirring speed to precipitate methane hydrate crystals having a larger particle size than the above. Then, after mixing both methane hydrate crystals, the mixture is discharged out of the system. (2) The temperature and pressure in the first and second pressure vessels are 1 to 4 ° C. and 30 to 100 atm, and the raw material gas and the water or the antifreeze are each in a weight ratio of about 1: 6. The pressure is supplied to the pressure vessel, the stirring speed (peripheral speed) of the stirrer in the first pressure vessel is 2 to 20 m / s, and the stirring speed (peripheral speed) of the stirrer in the second pressure vessel is 0.1 m / s. A method for producing a gas hydrate, which is set to 5 to 5 m / s.

The rotary stirrer used in the present invention is a rotary stirrer in which a raw material gas collides with a propeller type stirrer, or a rotor having a spiral chamber such as a centrifugal pump is rotated at a high speed to convert the raw material gas and water or antifreeze. Some of them are sucked and collided inside.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing an example of an apparatus used for the method for producing methane hydrate of the present invention. This device is
A first pressure vessel 1, a line 3 for supplying a raw material gas containing methane as a main component and water or an antifreeze into the vessel 1, a stirrer 2 inserted in the center of the vessel 1 and a drive motor 4 for the stirrer 2 A methane hydrate discharge pipe 5 provided at the bottom of the vessel 1, a second pressure vessel 6 which is not connected, a stirrer 7 inserted into the center of the vessel 6, and a drive motor 8 thereof. And a methane hydrate discharge pipe 8 provided at the bottom of the container 6.

Each of the pressure vessels 1 and 6 has a cooling jacket (not shown) through which a refrigerant flows. The ratio of raw material gas and water supplied to the first pressure vessel is 20 to 50% of the whole
The ratio of the raw material gas and water supplied to the second pressure vessel is 50 to 80% of the whole (weight basis, the same applies hereinafter). The pressure and temperature in the vessel are maintained at the reaction temperature and pressure at which methane hydrate is generated, usually in the range of 1 ° C to 4 ° C and 30 to 100 atm.

In the above system, natural gas and water or antifreeze are supplied from the line 3 to the first pressure vessel 1 at a ratio of about 1: 6 by weight at a first stirring speed. (2-20 m / s) with high speed stirring,
Microcrystalline methane hydrate is generated and discharged from the discharge pipe 5. On the other hand, natural gas and water or antifreeze having the same blending ratio as described above are supplied to the second pressure vessel 6, and
At a low stirring speed (0.5 to 5 m / s) to produce methane hydrate of crystal grains larger than the microcrystals. The methane hydrate of the relatively large crystal particles is discharged from the discharge pipe 8 and mixed with the methane hydrate of the microcrystals from the discharge pipe 5 in the mixing tank 9 to obtain the product 10
Is discharged outside the system. In the present invention, small-diameter particles are produced by high-speed stirring in the container 1, and large-diameter particles are produced by low-speed stirring in the container 6, and these mixtures are mixed in the mixing tank 9 in a so-called close-packed configuration. It is preferable to adjust the supply ratio and the stirring speed of the raw material gas and water at the stirring speed of the first and second pressure vessels.

[0009] The methane hydrate obtained as described above is suitable for transportation in a high-density, low-viscosity, smooth state. Hereinafter, specific examples of the present invention will be described below.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a first pressure vessel having a capacity of 10 liters and a second pressure vessel having a capacity of 15 liters were used, and 1 kg of a 1: 6 mixture (3 kg) of natural gas and water or antifreeze was used for the first pressure vessel. The remaining 2 kg was supplied into the second pressure vessel. A centrifugal pump type rotary stirrer is provided in each pressure vessel. The temperature and pressure of the first pressure vessel are 1 ° C., 40 atm, stirring speed 10 m / s,
The temperature and pressure of the second pressure vessel were 1 ° C., 40 atm, and the stirring speed was 2 m / s. The methane hydrate microcrystals (average particle size: 0.1 mm) obtained by reacting for 1 hour in the first pressure vessel were 1 kg. On the other hand, the methane hydrate crystal (average diameter 1.5 mm) obtained by reacting in the second pressure vessel for 1 hour was 2 kg. The product obtained by stirring and mixing these crystals in the mixing tank 9 was in the form of a smooth slurry.

[0011]

According to the present invention, a methane hydrate suitable for transportation or the like can be industrially produced by continuously reacting a gas containing methane as a main component with water or an antifreeze.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a methane hydrate production apparatus of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st pressure container, 2 ... Stirrer, 3 ... Supply line of natural gas and water or antifreeze, 4 ... Drive motor, 5 ...
Discharge pipe, 6: second pressure vessel, 7: stirrer, 8: discharge pipe, 9: mixing tank.

Claims (2)

[Claims] 1. A raw material gas containing methane as a main component and water or an antifreeze are supplied to a first pressure vessel and stirred at a high speed by a rotary stirrer to generate methane hydrate microcrystals. The raw material gas and water or antifreeze are supplied to the second pressure vessel, and the same stirrer is used to stir at a lower stirring speed than the above-mentioned stirring speed to form methane hydrate crystals having a larger particle diameter than the above. A method for producing a gas hydrate, comprising precipitating, mixing both methane hydrate crystals, and discharging the mixture outside the system. 2. The temperature and pressure in the first and second pressure vessels are set at 1 to 4 ° C. and 30 to 100 atm, and the raw material gas and water or antifreeze are each in a weight ratio of about 1: 6.
And the stirring speed (peripheral speed) of the stirrer in the first pressure vessel is 2 to 20 m / s, and
The stirring speed (peripheral speed) of the stirrer in the pressure vessel of 0.5 to 5
m / s, a method for producing gas hydrate.