JP2003238976A - Apparatus for producing gas hydrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for producing a gas hydrate which can efficiently produce the gas hydrate. <P>SOLUTION: A boiloff gas ejecting means 5 is provided at the lower part of a gas hydrate producing tank 1 and, at the same time, a circulating pipe 6 through which the boiloff gas ejecting means 5 communicates with the upper part of the gas hydrate producing tank is provided. Furthermore, a circulating fan 7 is provided on the circulating pipe 6 to form a circulating flow which is circulated out of the gas hydrate producing tank 1 and through the circulating pipe 6 and, simultaneously, a gas hydrate c formed in the gas hydrate producing tank 1 is positively agitated by the circulating flow. Moreover, a gas hydrate cooling means 9 to cool the gas hydrate c is provided in the gas hydrate producing tank 1. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generates boil-off gas (BOG) in which a part of liquefied natural gas (LNG) stored in a storage tank is vaporized into gas hydrate (NGH), and also stores and gasifies it. The present invention relates to technology for using BOG.

[0002]

2. Description of the Related Art Generally, natural gas is stored as LNG (liquefied natural gas) at a low temperature of about -164 ° C. L
In the LNG storage tank in which NG is stored, the amount of L being stored is about 0.1% / day due to the heat entering the tank.
NG is vaporized and boil-off gas (BOG) is generated.

The generated BOG is liquefied again and returned to the LNG storage tank, or after being pressurized by a gas compressor and stored in a gas holder or the like, it is supplied to the city as city gas. A large amount of electric power energy is required both when the BOG is liquefied again and when the pressure is increased by the gas compressor. Therefore, a technique for effectively utilizing a large amount of BOG is desired.

By the way, there is known a technique for producing a gas hydrate by introducing BOG and water into a hydrate production tank. However, even if BOG and water are simply introduced into a hydrate production tank, the gas hydrate is produced. Is difficult to manufacture efficiently.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a gas hydrate manufacturing apparatus capable of efficiently manufacturing gas hydrate.

[0006]

In order to solve the above problems, a gas hydrate production apparatus according to the invention of claim 1 introduces boil-off gas and water into a gas hydrate production tank. A gas hydrate production apparatus for producing gas hydrate, wherein boil-off gas ejection means for ejecting boil-off gas is provided in a lower portion of the gas hydrate production tank, and the boil-off gas ejection means and an upper portion of the gas hydrate production tank. And a circulation fan is provided in the circulation pipe to form a circulation flow around the gas hydrate production tank and the circulation pipe, and in the gas hydrate production tank by the circulation flow. The gas hydrate produced in 1. is positively stirred, and further, the gas hydrate production tank A gas hydrate production apparatus comprising providing a gas hydrate cooling means for cooling the gas hydrate.

In the gas hydrate production apparatus according to the second aspect of the present invention, the gas hydrate produced in the gas hydrate production tank is sent to the pyrolysis tank, and the gas hydrate is produced in the pyrolysis tank. It is a gas hydrate manufacturing apparatus of Claim 1 which thermally decomposes.

In the gas hydrate production apparatus according to the third aspect of the present invention, the gas hydrate production tank is connected to a gas hydrate production tank and a lower portion of the gas hydrate production tank. And a boil-off gas supply pipe for supplying boil-off gas to the gas injection pipe, and the boil-off gas supply pipe and the gas hydrate. The gas hydrate production apparatus according to claim 1 or 2, wherein the production tank is connected to the production tank via a circulation pipe, and the circulation pipe is provided with a circulation fan and a cooling means.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view of a gas hydrate production apparatus according to the present invention. In FIG. 1, 1 is a vertically long gas hydrate production tower, which also serves as a storage tank. Two
Is a boil-off gas supply pipe attached to the bottom of the gas hydrate generation tower 1, and is adapted to supply the boil-off gas (BOG) a in which LNG in the LNG tank (not shown) is vaporized into the gas hydrate generation tower 1. ing. Three
Is a water spray nozzle provided at the top of the gas hydrate production tower 1, and sprays the water b supplied from the water supply pipe 4 into the gas hydrate production tower 1. The water spray nozzle 3 is equipped with an electric heating type defrosting device (not shown) to prevent freezing.

A gas injection pipe 5 is provided as close to the bottom of the gas hydrate production tower 1 as possible and has a large number of gas ejection holes (not shown). Reference numeral 6 is a circulation pipe that connects the gas injection pipe 5 and the top of the gas hydrate generation tower 1, and a gas circulation fan 7 is provided in the middle thereof. A gas delivery pipe 8 is connected to the circulation pipe 6.

Further, a cooling means 9 for applying a heat medium and a heating means 10 for applying a heat medium are provided slightly above the gas injection pipe 5, and at the bottom of the gas hydrate production tower 1 is recovered. The water pipe 11 is connected. 1
Reference numerals 2, 13 and 14 denote valves. Further, at least two gas hydrate generation towers 1 (three in the case of the figure) are installed.

Next, the operation of this gas hydrate production apparatus will be described.

When the boil-off gas (BOG) a is supplied from the boil-off gas supply pipe 2 into the gas hydrate formation tower 1 and the gas circulation fan 7 is operated, the boil-off gas (BOG) a is generated. And a circulation pipe 6 are circulated in a closed loop.

When water b is sprayed there from a water spray nozzle 3 at the top of the gas hydrate generating tower 1 and supplied as water having a fine particle size, it is a hydrate of water and boil-off gas (BOG). A certain gas hydrate (NGH) c is produced. The heat generated when the hydrate is produced is removed by using the cold heat of LNG supplied to the cooling means 9.

Although the gas hydrate (NGH) c is deposited on the bottom of the gas hydrate production tower 1, the boil-off gas (5) ejected from the boil-off gas injection pipe 5 provided near the bottom of the gas hydrate production tower 1 ( Since it is blown up by BOG) a, it is always fluidized.

Therefore, the production of the gas hydrate (NGH) c is further promoted, and the gas hydrate (NGH) c does not freeze on the cooling tube constituting the cooling means 9, so that the cooling is performed. It is possible to prevent the functional deterioration of the means 9.

When a predetermined amount of gas hydrate (NGH) c is generated, the valves 12 and 14 are closed to stop the boil-off gas (BOG) a and water b, and the gas hydrate (NGH) is generated in the gas hydrate generation tower 1. Store c.

When the natural gas d is taken out from the gas hydrate production tower 1, the valve 13 of the gas delivery pipe 8 and the valve (not shown) of the condensate pipe 11 are opened, and then the hot water brine e is applied to the heating means 10. Supply. Then, the boil-off gas (BOG) c in the gas hydrate production tower 1
Is decomposed into natural gas d and water b, the natural gas d is supplied to the demand area through the gas delivery pipe 8, and the water b is stored in the tank (not shown) from the condensate pipe 11 and again gas hydrate ( NGH). Regeneration of natural gas may be carried out all at once in all the gas hydrate production towers 1, but it may also be carried out one by one in order.

Natural gas d is a gas hydrate (NG
Since it expands to about 170 times the volume of H) c, boosting by a compressor is not necessary. This is also clear from the dissociation curve from generation to decomposition of gas hydrate (NGH) in FIG.

FIG. 2 is a schematic view showing another embodiment of the gas hydrate production apparatus according to the present invention. In this gas hydrate production apparatus, high pressure gas hydrate (NGH) is decomposed in the gas separation tower 15 so that the gas hydrate production tower 1 does not have a high-pressure container structure.

The same parts as those of the gas hydrate production apparatus of FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted, but the gas hydrate (NGH) c produced in the gas hydrate production tower 1 is, for example, It is adapted to be supplied to the gas separation tower 15 by a transfer means 16 such as a screw conveyor. The transfer means 16 and the bottom of the gas hydrate production tower 1 are connected by a pipe 18 having a valve 17, the boil-off gas supply pipe 2 is connected to the body of the gas hydrate production tower 1, and a gas delivery pipe 8 is provided. Are connected to the gas separation tower 15.

By the way, the LNG tank has a temperature of about -164 ° C.
The temperature of the boil-off gas (BOG) a generated from the LNG tank is −90 ° C. to −130 ° C.
℃.

Therefore, the generated gas hydrate (NG
If the H) c is exposed to the low temperature boil-off gas (BOG) a for a long time, the gas hydrate (NGH) c may be overcooled.
Can be improved as shown in FIG.

The gas hydrate production tower 1 comprises a gas hydrate production tank 21 and a cylindrical body 22 having a diameter smaller than that of the gas hydrate production tank 21. A water spray nozzle 3 is provided on the top of the gas hydrate production tank 21, and an upward boil-off gas injection pipe 23 is provided in the cylinder 22 connected to the lower portion of the gas hydrate production tank 21. ing.

A boil-off gas supply pipe 2 for supplying a boil-off gas (BOG) a is connected to the boil-off gas injection pipe 23. This boil-off gas supply pipe 2
Is connected to the gas hydrate production tank 21 via the circulation pipe 6. The circulation pipe 6 is provided with a circulation fan 7 and a cooling means 9. Further, below the cylindrical body 22, a transfer means 16 such as a screw conveyor is provided.

In the gas hydrate production tower 1, when a gas hydrate (NGH) c which is a hydrate of boil-off gas (BOG) a and water b is produced, the inside of the cylinder 22 below the boil-off gas injection pipe 23. Because it will descend towards
The low temperature boil-off gas (BOG) a ejected from the boil-off gas injection pipe 23 is not exposed for a long time. The gas hydrate (NGH) c in the cylindrical body 22 is transferred to a storage tank (not shown) by the transfer means 16 such as a screw conveyor.

[0028]

As described above, the present invention is a gas hydrate production apparatus for producing a gas hydrate by introducing boil-off gas and water into a gas hydrate production tank. A boil-off gas ejecting means for ejecting boil-off gas is provided at the bottom of the manufacturing tank, and a circulation pipe is provided which connects the boil-off gas ejecting means and the upper part of the gas hydrate manufacturing tank,
Further, a circulation fan is provided in the circulation pipe to form a circulation flow around the gas hydrate production tank and the circulation pipe, and the gas hydrate produced in the gas hydrate production tank by the circulation flow is positively activated. Since the gas hydrate cooling means for cooling the gas hydrate is provided in the gas hydrate manufacturing tank, the following effects can be obtained.

That is, the produced gas hydrate (NGH) c is deposited at the bottom of the gas hydrate production tower, but is boiled off from a boil-off gas injection pipe provided near the bottom of the gas hydrate production tower. Since it is blown up by the gas (BOG) a, it always fluidizes.

Therefore, since the production of the gas hydrate (NGH) c is further promoted and the gas hydrate (NGH) c does not freeze on the cooling tube which constitutes the cooling means, the cooling means. Can be prevented.

The heat generated when the gas hydrate (NGH) c, which is a hydrate of water and boil-off gas (BOG), is generated is removed by using the cold heat of LNG supplied to the cooling means. For gas hydrate (NGH)
The production of c is promoted.

Further, according to the present invention, the gas hydrate produced in the gas hydrate production tank is sent to the pyrolysis tank, and the gas hydrate is pyrolyzed in this pyrolysis tank. Therefore, the gas hydrate production tank is forced to a high pressure. Since there is no need to use a tank, the manufacturing cost of the gas hydrate manufacturing tank can be reduced.

Further, according to the present invention, the gas hydrate production tank is formed from a gas hydrate production tank and a vertically elongated cylinder connected to the lower portion of the gas hydrate production tank, and the gas hydrate production tank is directed upward in the cylinder. Of the gas injection pipe, further connecting the boil-off gas supply pipe for supplying boil-off gas to the gas injection pipe, and connecting the boil-off gas supply pipe and the gas hydrate production tank via a circulation pipe, and Since the circulation fan and the cooling means are provided in the circulation pipe, the supercooling of the gas hydrate can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic view of a gas hydrate production apparatus according to the present invention.

FIG. 2 is a schematic view showing another embodiment of the gas hydrate production apparatus according to the present invention.

FIG. 3 is a schematic view showing another example of a gas hydrate production tank.

FIG. 4 is a diagram showing a dissociation curve from generation to decomposition of gas hydrate (NGH).

[Explanation of symbols]

a boil-off gas b water c gas hydrate 1 gas hydrate production tank 5 Boil-off gas ejection means 6 circulation pipe 7 Circulation fan 9 Gas hydrate cooling means

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C07C 7/20 C07C 9/04 9/04 F17C 11/00 B F17C 11/00 13/00 302A 13/00 302 C10L 3 / 00 A (72) Inventor Hajime Kanda 5-6-4 Tsukiji, Chuo-ku, Tokyo F-term within Mitsui Engineering & Shipbuilding Co., Ltd. (reference) 3E072 AA03 EA10 3E073 DD05 4G075 AA03 CA03 CA65 CA66 EB01 4H006 AA02 AA04 AD40

Claims (3)

[Claims] 1. A gas hydrate production apparatus for producing gas hydrate by introducing boil-off gas and water into a gas hydrate production tank, wherein the boil-off gas is jetted to the lower part of the gas hydrate production tank. Is provided with a boil-off gas jetting means, and a circulation pipe that connects the boil-off gas jetting means with the upper part of the gas hydrate production tank is provided, and a circulation fan is provided in the circulation pipe to provide the gas hydrate production tank and the A circulation flow is formed around the circulation pipe, the gas hydrate produced in the gas hydrate production tank is positively stirred by the circulation flow, and the gas hydrate is cooled in the gas hydrate production tank. A gas hydrate production apparatus provided with a gas hydrate cooling means for 2. The gas hydrate production apparatus according to claim 1, wherein the gas hydrate produced in the gas hydrate production tank is sent to a pyrolysis tank, and the gas hydrate is pyrolyzed in the pyrolysis tank. 3. The gas hydrate production tank is formed of a gas hydrate production tank and a vertically elongated cylinder connected to a lower portion of the gas hydrate production tank, and an upward gas jet is injected into the cylinder. A pipe is installed,
A boil-off gas supply pipe for supplying boil-off gas is connected to the gas injection pipe, the boil-off gas supply pipe and a gas hydrate production tank are connected through a circulation pipe, and a circulation fan and cooling are connected to the circulation pipe. The gas hydrate production apparatus according to claim 1, further comprising means.