JPH04316795A - Storage system for natural gas - Google Patents

Abstract

PURPOSE:To store natural gas and to send it to consumers after regasification by using a simple equipment and at a small cost. CONSTITUTION:Natural gas is absorbed into water solution 6 of hydrate formation accelerator in a storage tank 1 for converting the natural gas to hydrate so as to store it. Then, the natural gas converted to the hydrate is heated by means of a heating heat exchanger for regasification. This regasificated natural gas is extracted and sent to a consumer side. By this constitution, it is possible to store natural gas at a small cost and also to omit the conventional refrigerating equipment, which is necessary for lique-faction, and electric power consumption for operating it and also it is not necessary to provide any vaporizing equipment on purpose.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for converting natural gas into hydrates, storing and regasifying the hydrates.

0002

2. Description of the Related Art Natural gas has the property of liquefying when frozen to -162°C, and when liquefied, its volume becomes 1/600. Therefore, when storing natural gas, the natural gas is first liquefied and stored in a storage tank, and when consumed, the liquefied natural gas (hereinafter referred to as "LNG") is gasified using a vaporizer.

[0003] Thus, when storing natural gas, refrigeration equipment is required for liquefaction, and its operation consumes a large amount of electricity.

[0004] In addition, the above-mentioned liquefaction method is also used as a means of transporting natural gas by tanker. In addition, a reliquefaction method using refrigeration equipment has been adopted as a method for disposing of a large amount of BOG generated when LNG transported by tanker is received in a receiving tank at a receiving terminal.

[0005]

[Problems to be Solved by the Invention] As described above, the conventional method of storing natural gas involves freezing it to -162°C and liquefying it, which incurs enormous costs in terms of equipment costs, electricity costs, etc.

[0006] Furthermore, in order to gasify LNG, a vaporizer is required, and this vaporization equipment and operation also require a large amount of cost.

An object of the present invention is to provide a natural gas storage system that is particularly effective when applied to small-scale natural gas storage and regasification or, for example, BOG processing equipment at natural gas satellite bases. be.

[0008]

[Means for Solving the Problems] The structure of the present invention is as follows.

[0009] A storage tank filled with an aqueous solution of a hydrate formation accelerator, a natural gas jet pipe inserted into the aqueous solution in the storage tank, and a heating pipe inserted into the aqueous solution in the storage tank. The natural gas jetting pipe vigorously jets natural gas into the aqueous solution in the storage tank, and uses the kinetic energy of this jetting to stir the aqueous solution and promote natural gas absorption, and the heating means A natural gas storage system characterized by performing a vaporization action to heat and separate natural gas that has been absorbed into an aqueous solution and converted into hydrates in a tank and taken out of the storage tank.

0010

[Operation] The storage tank is filled with an aqueous solution of a hydrate formation accelerator (for example, an aqueous solution of fatty amines). Natural gas is vigorously jetted into the aqueous solution from the natural gas jet pipe, and the kinetic energy is used to stir the aqueous solution, increasing absorption efficiency, absorbing it into the aqueous solution, and converting it into hydrates. During this conversion, heat is emitted, so this heat may be absorbed by the cold heat of the liquefied natural gas, for example, by installing an endothermic heat exchanger inside or outside the storage tank, or by installing an endothermic heat exchanger inside or outside the storage tank.
In the case of G, since it is usually in an extremely low temperature state, the heat generation may be absorbed using this sensible heat. Of course, the sensible heat of BOG and the cold heat of liquefied natural gas may be used together.

[0011] Natural gas converted to hydrate and stored in a storage tank is separated and gasified when heated by a heating means, so it can be reused while controlling heating (heat input) according to the consumption amount. It is gasified, taken out of the storage tank, and sent to the consumer.

Alternatively, it is also possible to transport the converted hydrate to another location by pipe or tank truck.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a storage system according to the present invention. The code 1 is the storage tank, and 2 is the natural gas receiving line (BOG).
3 is a natural gas jetting pipe inserted into the storage tank 1, and this natural gas jetting pipe 3 is connected to the natural gas receiving line 2.

Reference numeral 4 denotes a heating heat exchanger as a heating means built into the storage tank 1, in which a heating medium circulates in the embodiment.

5 is a natural gas output line, 6 is a storage tank 1
The natural gas jet pipe 3 and the heating heat exchanger 4 are immersed in the aqueous solution 6 of a hydrate formation promoter.

FIG. 2 shows an embodiment in which a storage system according to the present invention is used for processing BOG generated from an LNG storage tank 7 at a satellite base. Natural gas enters the storage tank 1 via the natural gas receiving line 2 and is ejected from the natural gas jetting pipe 3 into the aqueous solution 6 in the storage tank 1, and this kinetic energy agitates the aqueous solution 6, thereby increasing absorption efficiency. However, it is absorbed into the aqueous solution 6 and converted into a hydrate.

When consuming the natural gas stored in this way, the natural gas converted into hydrates is heated by passing a heating medium through the heating heat exchanger 4 shown in FIG. The gas and the aqueous solution 6 are separated, and the natural gas with a light specific gravity can be taken out from the natural gas output line 5 equipped with a heater 9, and the aqueous solution 6 with a heavy specific gravity remains in the storage tank 1 and is reintroduced. It is used to absorb incoming natural gas. In FIG. 2, 10 is an LNG receiving line, and 11 is an LNG pumping line.

[0018]

[Effects of the Invention] As described above, the present invention has constructed a storage system that can convert natural gas into a hydrate, store it, gasify it again, and send it to the consumer.The present invention has the following effects. You can expect it.

a. Since the present invention employs a method of storing natural gas in the form of hydrate, a large amount of natural gas can be stored at a lower pressure than the conventional compression storage method. therefore,
There is no need for conventional refrigeration equipment and the huge amount of electricity required to operate this refrigeration equipment. Therefore, it is particularly applicable to small-scale natural gas storage bases (satellite bases), and is effective as BOG processing equipment.

b. A heating heat exchanger is installed in the storage tank, and by driving the heat exchanger, heat is applied to the natural gas converted to hydrates, and the gas can be taken out and consumed at will. Therefore, during regasification, there is no need for conventional vaporization equipment.

c. Natural gas is ejected into an aqueous solution in a storage tank, and this kinetic energy agitates the aqueous solution, increasing the absorption rate of natural gas and enabling its hydrate conversion, i.e., an increase in the amount of natural gas accepted. .

d. BOG reduces the heat generated by absorption of natural gas.
If the sensible heat is used to absorb the heat, a heat absorption device is not necessary or only needs to be used as an auxiliary aid.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a storage system according to the present invention.

FIG. 2 is an explanatory diagram in which the storage system of the present invention is applied to a natural gas satellite base.

[Explanation of symbols]

1 Storage tank 2 Natural gas receiving line 3 Natural gas jet pipe 4 Heating heat exchanger 5 Natural gas output line 6 Hydrate formation accelerator aqueous solution 7 LNG storage tank 8　BOG exit line 9 Heating heater 10 LNG receiving line 11 LNG pumping line

Claims (3)

[Claims] Claim 1: A storage tank filled with an aqueous solution of a hydrate formation accelerator, a natural gas jet pipe immersed and inserted into the aqueous solution in the storage tank, and a natural gas jet pipe immersed and inserted into the aqueous solution in the storage tank. The natural gas jetting pipe vigorously jets natural gas into the aqueous solution in the storage tank, and uses the kinetic energy of this jet to agitate the aqueous solution and promote natural gas absorption. A natural gas storage system, characterized in that natural gas absorbed in an aqueous solution and converted into hydrates in a storage tank is heated, separated, and vaporized to be taken out of the storage tank. 2. The natural gas storage system according to claim 1, wherein BOG generated in the liquefied natural gas storage tank is introduced into the storage tank from a natural gas jet pipe, converted into a hydrate, and stored. 3. The natural gas storage system according to claim 1, wherein the cooling energy of the liquefied natural gas is used to absorb the heat generated when the natural gas is converted into a hydrate.