JP2003307299A - Hydrate tank device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrate tank device suitable for hydrating and transporting raw gas. <P>SOLUTION: This device comprises a tank 1 for generating hydrate, a heat exchanger 2 for setting/maintaining a temperature inside the tank 1 at one of conditions for generating hydrate, for storing hydrate and for vaporizing hydrate, a raw gas feed part 12 with an open/close valve 11 for feeding raw gas inside the tank 1 for generating hydrate at the time of generating hydrate, a medium feed part 22 with an open/close valve 21 for feeding water W as a medium for generating hydrate inside the tank 1 at the time of generating hydrate, a gas outlet pipe passage with an open/close valve 31 for discharging gas generated inside the tank 1 to outside the tank 1, and a relief valve 40 for relieving gas pressure to outside the tank 1 when the gas pressure inside the tank 1 increases above a predetermined value. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses one tank to produce a hydrate by a hydrate-forming reaction between a source gas (eg, methane) forming a hydrate and a medium (eg, water). The present invention relates to a hydrate tank device that can store, store, and vaporize it to supply it to a consumer as fuel gas.

[0002]

2. Description of the Related Art It is known that natural gas components such as methane are distributed in large amounts as hydrates in underground areas of cold regions. Since these hydrates stably exist under conditions of low temperature and high pressure, they are expected as a next-generation natural gas source. In particular, methane hydrate (hereinafter referred to as “methane hydrate”) is a type of clathrate compound (clathrate) in which methane molecules are contained in a cage composed of three-dimensionally arranged water molecules. Since the intermolecular distance of methane in the Japanese basket is shorter than the intermolecular distance in the high pressure filled gas cylinder, it is in a tightly packed state.
Transportation is expected. On the other hand, research that not only depends on natural resources but also efficiently produces methane hydrate is under way.

[0003] Conventionally, an example of a storage device for generating a hydrate, storing it, and vaporizing it when necessary is disclosed in Japanese Patent Laid-Open No. 2001-2001.
No. 165397. This storage device is attached to a part of the natural gas supply line, and in a situation where surplus gas is generated, part of the natural gas is hydrated and stored to reduce its volume, and the amount of gas used increases. During the period, the hydrate is vaporized and returned to the gas supply line. According to this storage device, hydrate can be generated by controlling the temperature with the cooling pipe and the heating pipe, and the hydrate can be gasified. Therefore, the hydrate is moved within the plant. There is no need, and there is an advantage that the plant configuration can be simplified.

[0004]

However, the above-mentioned storage device is interposed in a part of a line for supplying gas to a consumer, and is always used in a state where it is connected to the gas line. And its function is limited to buffers. In other words, it functions as a permanent fixed facility, and was not developed with the intention of transporting the hydrate together with the storage device to another place.
Therefore, if it is planned to transport methane gas in a hydrated state from a gas production site to a gas consumption site, there is a risk of safety problems even if the conventional idea is applied to the plan as it is.

In view of the above circumstances, it is an object of the present invention to provide a hydrate tank device suitable for transporting a raw material gas in a hydrated state.

[0006]

A hydrate tank device according to a first aspect of the present invention is a tank for hydrate generation, the temperature and pressure inside the tank, the conditions for generating hydrate, and the hydrate. And a temperature and pressure condition setting means for setting and maintaining any one of the condition for storing the gas and the condition for vaporizing the hydrate.

In this hydrate tank device, when producing a hydrate, first, the raw material gas and the medium are kept in a state in which the temperature inside the tank is set and maintained at a condition where the hydrate can be produced by the temperature / pressure condition setting means. Install in the tank. Then, by setting and maintaining the hydrate generation condition, the source gas is hydrated.
When a predetermined amount of hydrate can be achieved, the temperature and pressure conditions inside the tank are set and maintained at a temperature and pressure suitable for storage. As a result, the tank itself can be transported (that is, it becomes a portable tank), and the gas can be transported from the production source of the raw material gas to the consumption location in a state where the volume is reduced by hydration. When the hydrate is gasified and supplied to the consumption area after the tank is transported to the vicinity of the consumption area, the temperature inside the tank is set and maintained at the vaporization condition by the temperature / pressure condition setting means. By doing so, the hydrate can be gasified and sent to the consumer. In this case, when the gas is taken out from the tank, it is taken out in the gas state instead of the hydrate state, so that there is no problem such as blockage during transportation.

According to another aspect of the hydrate tank apparatus of the present invention, a raw material gas supply unit with an on-off valve for supplying a raw material gas for producing hydrate to the inside of the tank during hydrate production, and the above-mentioned raw gas during hydrate production. A medium supply unit with an on-off valve for supplying a medium for producing hydrate to the inside of the tank, a gas outlet line with an on-off valve for taking out gas generated inside the tank to the outside of the tank, and a gas pressure inside the tank is predetermined. A safety valve is provided to release the gas pressure to the outside of the tank when the pressure rises above.

In the hydrate tank device, when producing a hydrate, first, the raw material gas supply line is connected to the raw material gas supply unit and the medium supply line is connected to the medium supply unit. Then, while the temperature inside the tank is set and maintained by the temperature and pressure condition setting means so that hydrate can be generated, the open / close valves of both supply units are opened to introduce the raw material gas and the medium into the tank. In this case, the pressure condition inside the tank can be set by the supply pressure of the raw material gas. By setting and maintaining the hydrate generation condition in this manner, the source gas is hydrated. When a predetermined amount of hydrate can be achieved, the on-off valves of the raw material gas supply unit and the medium supply unit are closed to disconnect the supply units from each supply line. Then, in order to maintain this state, the temperature and pressure condition inside the tank is set and maintained at a temperature and pressure suitable for storage. As a result, the tank itself can be transported (that is, it becomes a portable tank), and the gas can be transported from the production source of the raw material gas to the consumption location in a state where the volume is reduced by hydration.

By the way, there is a possibility that the pressure inside the tank will rise more than necessary due to temperature rise during the storage and transportation. At that time, the safety valve opens and the gas pressure is automatically released. There is no risk that the internal pressure will rise above a predetermined level, and safety can always be maintained. For example, when tanks are transported by air or land, there is no danger of problems because they can reach their destinations in a short time, but when they are transported by sea, they are transported for a long time, making temperature and pressure management difficult. , The pressure inside the tank may rise excessively. However, in the case of this device, since the safety valve is provided, the hydrate can be safely stored and transported within the limit of the specified pressure. Therefore, the pressure resistance of the tank can be suppressed to a low level, and a compact, lightweight, and low-cost tank can be used.

When the tank is transported to the vicinity of the consuming place and then the hydrate is gasified and supplied to the consuming place, first, a gas delivery line is connected to the gas outlet pipe line and the gas outlet pipe is connected. The on-off valve provided in the passage is opened, and the temperature inside the tank is set and maintained at the vaporization condition by the temperature / pressure condition setting means. By doing so, the hydrate can be gasified and sent to the consumer. In this case, when the gas is taken out from the tank, it is taken out in the gas state instead of the hydrate state, so that there is no problem such as blockage during transportation.

A third aspect of the present invention is characterized in that, in the hydrate tank device according to the first or second aspect, the tip of the pipe line in which the safety valve is interposed is connected to a flare stack.

In this device, the safety valve is opened and the gas escaped is burned by the flare stack, so that the safety can be maintained.

According to a fourth aspect of the present invention, in the hydrate tank device according to any one of the first to third aspects, the temperature / pressure condition setting means is a heat exchanger for adjusting the temperature inside the tank by circulating the refrigerant. And a refrigerant control means for controlling the amount of the refrigerant flowing into the heat exchanger or the temperature of the refrigerant to be circulated.

In this apparatus, the temperature inside the tank is controlled by controlling the flow rate of the refrigerant flowing in the heat exchanger or the temperature of the refrigerant, so that the temperature condition for producing the hydrate, the temperature condition for storing the hydrate, and the hydrate. Are adjusted to three temperature levels of vaporizing temperature. Therefore, the temperature inside the tank can be controlled easily and reliably.

According to a fifth aspect of the present invention, in the hydrate tank device according to the fourth aspect, the heat exchanger used for vaporizing the hydrate is arranged in at least one of the tank upper layer portion and the tank side wall portion. It is characterized by having done.

In this apparatus, since the hydrate can be vaporized from the tank upper layer portion and the tank side wall portion, it is possible to prevent the hydrate in the tank from collapsing during gasification.

According to a sixth aspect of the present invention, in the hydrate tank device according to any one of the first to fifth aspects, hydrate production amount detecting means for detecting the amount of hydrate produced inside the tank is provided. Is characterized by.

Since this apparatus can detect the amount of the generated hydrate, the hydrate can be efficiently manufactured. As the detecting means, a level detecting means such as an ultrasonic sensor can be used.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the embodiment of the present invention, the case where methane gas is used as the raw material gas for forming the hydrate will be described, but the raw material gas is not limited to pure methane gas, and any gas containing at least methane gas may be used. For example, natural gas including methane gas may be used.

FIG. 1 is a schematic configuration diagram of the hydrate tank device of the embodiment. In the figure, 1 is a tank for producing hydrate, which is provided with a heat insulating structure for the outside. Reference numeral 2 denotes a heat exchanger (cooling jacket, cooling coil, etc.) equipped inside the tank, and a refrigerant R is circulated in the heat exchanger 2 as necessary. Although a means for circulating the refrigerant and a means for controlling the temperature / flow rate of the refrigerant are omitted in the figure, by circulating the refrigerant through the heat exchanger 2, the temperature inside the tank 1 can be adjusted.

The heat exchanger 2 and a refrigerant control means (not shown) constitute a temperature / pressure condition setting means, and the inside of the tank 1 is controlled by controlling the amount of the refrigerant flowing into the heat exchanger 2 or the temperature of the refrigerant to be circulated. The temperature can be set and maintained at any one of the conditions for generating the hydrate H, the conditions for storing the hydrate H, and the conditions for vaporizing the hydrate H. The heat exchanger 2 used when vaporizing the hydrate H is provided in at least one of the upper layer portion of the tank 1 and the side wall portion of the tank 1 in order to prevent the hydrate H from collapsing during gasification. It is better to place

At the bottom of the tank 1, a raw material gas supply unit 12 with an opening / closing valve 11 for supplying a raw material gas for producing hydrate to the inside of the tank 1 at the time of hydrate production, and a raw material gas supply unit 12 at the inside of the tank 1 at the time of hydrate production. A medium supply unit 22 with an on-off valve 21 that supplies water W as a medium for hydrate generation is provided. In addition, a gas outlet conduit 32 with an opening / closing valve 31 for extracting gas generated inside the tank 1 to the outside of the tank 1 is provided on the ceiling of the tank 1, and a gas pressure when the gas pressure inside the tank 1 rises above a predetermined level. There is provided a safety valve 40 that escapes to the outside of the tank 1. The end of the pipe having the safety valve 40 is connected to the flare stack. Further, on the upper part of the tank 1, a hydrate production amount detecting means 50 such as an ultrasonic sensor for detecting the amount of the hydrate H produced in the tank 1 is provided.

Next, the operation will be described. This hydrate tank device uses one tank 1 to produce hydrate H, store hydrate H, and hydrate H.
FIG. 2 schematically shows the manufacturing process, FIG. 3 shows the storage process, and FIG. 4 schematically shows the gasification process.

In carrying out the hydrate manufacturing process of FIG. 2, first, the source gas supply line 12 is connected to the source gas supply line 13, and the medium supply unit 22 is connected to the medium supply line 23. Then, by flowing the refrigerant through the heat exchanger 2, the temperature inside the tank 1 is set and maintained under the hydrate generation condition, and in that state, the opening / closing valves 1 of both supply units 12 and 22 are maintained.
1, 1 and 21 are opened, and raw material gas and water W as a medium are introduced into the tank. In this case, the pressure condition inside the tank 1 is set by the supply pressure of the raw material gas.

By setting and maintaining the hydrate generation condition in this manner, the source gas is hydrated. When the source gas is methane gas, 2.6M when the temperature is 0 ° C
Hydrate at a pressure of Pa or higher. Also, the temperature is 5
Hydrate at a pressure of 4.6 MPa or higher at ℃. Methane gas is 1/100 to hydrated
The volume is reduced to 1/170.

When it is confirmed by the signal of the hydrate production amount detecting means 50 (see FIG. 1) that the hydration of a predetermined amount can be achieved, the open / close valves 11 of the raw material gas supply unit 12 and the medium supply unit 22, 21 is closed and the supply parts 12 and 22 are separated from the supply lines 13 and 23. Then, in order to maintain this state, the temperature inside the tank 1 is set and maintained at a temperature suitable for storage by adjusting the flow condition of the refrigerant as shown in FIG. In this state, the tank 1 itself can be transported. Therefore, it becomes possible to transport the gas from the production site of the raw material gas to the consumption site in a state of being reduced in volume by hydration.

For example, in this storage state, if the pressure inside the tank 1 rises more than necessary due to some reason, the safety valve 40 opens and the gas pressure is automatically released to burn the flare stack. Therefore, there is no risk that the pressure inside the tank 1 will rise above the allowable limit, and safety will always be maintained. Therefore, the hydrate can be safely stored and transported within the specified pressure limit even during long-time sea transportation.

When the tank 1 is transported to the vicinity of the consuming place and then the hydrate is gasified and supplied to the consuming place, first, as shown in FIG. 33 is connected to open the on-off valve 31 provided in the gas outlet conduit 32, and the temperature inside the tank 1 is maintained at the vaporization condition by adjusting the refrigerant circulation condition. By doing so, the hydrate H can be gasified and sent to the consumer. In this case, when the gas is discharged from the tank 1, the gas is discharged in the gas state instead of the hydrate state, so that problems such as blockage during transportation do not occur.

[0030]

As described above, according to the invention of claim 1, the hydrate can be produced, stored and vaporized in one tank. Therefore, it is not necessary to use a plurality of different tanks for each process of production, storage, and vaporization, and it is not necessary to transport the hydrate for each process, and it is possible to provide a compact device with less trouble. Therefore, it is possible to provide a hydrate tank device suitable for transporting the raw material gas after hydrating it.

According to the second aspect of the present invention, the raw material gas supply section, the medium supply section, and the gas outlet pipeline are each provided with an on-off valve. Therefore, the on-off valve is closed from the line except when necessary. Therefore, the tank itself can be transported, and the gas can be transported from the production source of the raw material gas to the consumption location in a state of being reduced in volume by hydration.
In addition, since the safety valve is provided, the hydrate can be safely stored and transported within the specified pressure limit.
The pressure resistance of the tank can be kept low, and it is possible to use a compact, lightweight, and low-cost tank.

According to the third aspect of the present invention, the safety valve is opened so that the escaped gas is burned in the flare stack, so that further safety can be achieved.

According to the fourth aspect of the present invention, the temperature inside the tank is controlled by controlling the flow rate of the refrigerant flowing in the heat exchanger or the temperature of the refrigerant, so that the temperature can be controlled easily and surely.

According to the fifth aspect of the invention, since the hydrate can be vaporized from the tank upper layer portion and the tank side wall portion, it is possible to prevent the hydrate from collapsing during gasification and to improve safety. Can be increased.

According to the sixth aspect of the present invention, since the amount of hydrate produced can be detected, the hydrate can be efficiently produced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a hydrate tank device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a manufacturing process in the same device.

FIG. 3 is an explanatory diagram of a storage process in the device.

FIG. 4 is an explanatory diagram of a gasification process in the apparatus.

[Explanation of symbols]

1 tank 2 Heat exchanger (temperature and pressure condition setting means) 11,21,31 on-off valve 12 Raw material gas supply section 22 medium supply unit 32 gas outlet line 40 safety valve 50 Hydrate production amount detecting means H hydrate W water

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hidetaka Ono             1-8 Koura, Kanazawa-ku, Yokohama-shi, Kanagawa               Mitsubishi Heavy Industries Yokohama Research Center F-term (reference) 3E072 AA03 EA07 GA30                 3E073 AA01 DB01 DC13 DC31

Claims (6)

[Claims] 1. A tank for producing a hydrate, a temperature and a pressure inside the tank, a condition for producing a hydrate, a condition for storing a hydrate, a condition for vaporizing the hydrate, And a temperature and pressure condition setting means for setting and maintaining any one of the above conditions. 2. A raw material gas supply part with an on-off valve for supplying a raw material gas for producing hydrate to the inside of the hydrate producing tank, and a medium for producing hydrate inside the tank when producing the hydrate. A medium supply unit with an on-off valve for supplying the gas, a gas outlet pipe line with an on-off valve for taking out gas generated inside the tank to the outside of the tank,
The hydrate tank apparatus according to claim 1, further comprising a safety valve that releases the gas pressure to the outside of the tank when the gas pressure inside the tank rises above a predetermined level. 3. The hydrate tank device according to claim 1, wherein the tip of the conduit having the safety valve interposed is connected to a flare stack. 4. The temperature and pressure condition setting means controls a temperature of a heat exchanger inside the tank by circulating the refrigerant, and a refrigerant control means for controlling a flow rate of the refrigerant to the heat exchanger or a temperature of the refrigerant to be passed. The hydrate tank device according to any one of claims 1 to 3, which comprises: 5. A heat exchanger used for vaporizing the hydrate is arranged in at least one of a tank upper layer portion and a tank side wall portion.
Hydrate tank device described in. 6. The hydrate tank device according to claim 1, further comprising hydrate production amount detection means for detecting the amount of hydrate produced inside the tank.