KR102040000B1 - Liquefied gas storage ship, and operating method thereof - Google Patents

Abstract

A liquefied gas storage vessel and its operating method are disclosed. The liquefied gas storage vessel according to an embodiment of the present invention is nitrogen gas or the demand source supplied from the demand source to at least one first storage tank of the liquefied natural gas supplied from the source of natural gas from the demand source of natural gas A nitrogen gas supply line for supplying nitrogen gas vaporized with liquid nitrogen supplied from the gas to vaporize the liquefied natural gas remaining in the first storage tank after unloading; A first compression unit receiving and compressing a mixed gas of natural gas and nitrogen gas in the first storage tank generated by nitrogen gas supply; A heating unit for heating the compressed mixed gas; And a heated mixed gas supply line for supplying the heated mixed gas to one or more second storage tanks in the storage tank to vaporize the liquefied natural gas remaining in the second storage tank after unloading.

Description

Liquefied gas storage vessel and its operation method {LIQUEFIED GAS STORAGE SHIP, AND OPERATING METHOD THEREOF}

The present invention relates to a liquefied gas storage vessel and its operation method.

Recently, with the tightening of the International Maritime Organization (IMO) regulations on the emission of greenhouse gases and various air pollutants, the shipbuilding and shipping industry replaces existing fuel oil, heavy oil and diesel oil with natural gas, which is a clean energy source. (Hereinafter referred to as "ship") as a fuel.

This natural gas is cooled to cryogenic temperatures of approximately -163 ° C for ease of storage and transportation, and converted to Liquefied Natural Gas (LNG) with a volume reduced by 1/600. Are stored in. The vessel stores liquefied natural gas in a storage tank and transports it to a remote demand site for unloading.

On the other hand, ships that have arrived at the demand destination by operating in the mountain area are supplied to the storage facility of the demand destination and unloaded, and then the storage tank is operated to the mountain area with empty storage tank for transportation of the liquefied natural gas again. This lowers the operating efficiency of the liquefied gas storage vessel has an inefficient aspect.

In addition, in order to eliminate the possibility of fire or explosion prior to shipping the liquefied gas to the storage tank, inert gas is supplied to the inside of the storage tank to remove oxygen. Then, a process of cooling the inner wall of the storage tank using a spray device is performed. For example, Korean Patent Laid-Open Publication No. 10-2010-0110500 (published on October 13, 2010) discloses a technology of performing a cooling operation after deactivating a storage tank using nitrogen.

However, for this purpose, the ship should be equipped with a separate nitrogen gas generator (N2 Generator) and related facilities on the hull, incurs facility costs and management costs.

Korean Patent Publication No. 10-2010-0110500 (published Oct. 13, 2010)

The embodiment of the present invention can be transported while storing the liquefied natural gas and liquid nitrogen in the storage tank alternately in the origin and demand of natural gas, through which the liquefied gas storage vessel and its operation method can be improved efficiency To provide.

In addition, to provide a liquefied gas storage vessel and a method of operating the liquefied gas storage and cooling operation for the liquefied natural gas remaining in the storage tank after receiving the nitrogen gas and liquid nitrogen from the demand source.

According to an aspect of the present invention, the liquefied natural gas supplied from the source of natural gas to the first storage tank of one or more of the storage tanks unloaded from the demand of the natural gas nitrogen gas supplied from the demand source or the liquid supplied from the demand source A nitrogen gas supply line for supplying nitrogen gas vaporized with nitrogen to vaporize liquefied natural gas remaining in the first storage tank after unloading; A first compression unit receiving and compressing a mixed gas of natural gas and nitrogen gas in the first storage tank generated by the vaporization operation; A heating unit for heating the compressed mixed gas; And a heated mixed gas supply line for supplying the heated mixed gas to at least one second storage tank of the storage tanks to vaporize the liquefied natural gas remaining in the second storage tank after unloading. Ships may be provided.

And a second compression unit configured to receive and compress a mixture of the natural gas and the mixed gas in the second storage tank generated by the heated mixed gas, and a first discharge line for discharging the compressed mixture toward the demand destination. can do.

A second discharge line for supplying and compressing a mixture of natural gas and the mixed gas in the second storage tank generated by the heated mixed gas to the first compression unit, and the first compression unit of the nitrogen gas supply line And a branching line branched from between the heating unit and the compressed mixture to send the compressed mixture toward the demand destination.

Spraying the liquid nitrogen supplied from the demand source through the spray line into the spray line connecting the storage tank and the demand source, and the storage tank after the vaporization process for the remaining liquefied natural gas after the unloading is completed It may further comprise a nozzle unit for cooling.

According to another aspect of the present invention, (a) from the nitrogen gas supplied from the source or the demand source to the first storage tank of one or more of the storage tanks unloaded from the source of the natural gas liquefied natural gas supplied from the source of natural gas Supplying nitrogen gas vaporizing the supplied liquid nitrogen to vaporize the liquefied natural gas remaining in the first storage tank after unloading; (b) compressing and heating a mixed gas of natural gas and nitrogen gas in the first storage tank generated by the vaporization operation and supplying it to one or more second storage tanks to liquefy remaining in the second storage tank after unloading. Vaporizing natural gas; And (c) cooling the first storage tank by injecting liquid nitrogen supplied from the demand source into the first storage tank to provide a method of operating a liquefied gas storage vessel.

After the step (b), the method may further include the step of receiving the compressed mixture of the natural gas and the mixed gas in the second storage tank generated by the heated mixed gas to be discharged toward the demand destination.

After the step (c), when the vaporization operation for the liquefied natural gas remaining in the second storage tank is being performed, the second storage tank by compressing and heating the gas generated in the first storage tank in which the cooling operation is performed. Supplying to, may further include the step of being used for the vaporization of the second storage tank.

The liquefied gas storage vessel and its operation method according to an embodiment of the present invention can be transported while alternately storing the liquefied natural gas and liquid nitrogen in the storage tank in the origin and demand of natural gas, thereby improving the efficiency of operation Can be.

In addition, by receiving nitrogen gas and liquid nitrogen from the demand source, it is possible to perform vaporization and cooling operations for the liquefied natural gas remaining in the storage tank after unloading.

In addition, after receiving the nitrogen gas from the demand source, and performing the vaporization work for the liquefied natural gas remaining in the first storage tank after unloading, the second storage after unloading the mixed gas of natural gas and nitrogen gas generated in the first storage tank By reducing the amount of nitrogen gas supplied from the demand source, it is used for the vaporization of the liquefied natural gas remaining in the tank and cooling the inside of the first storage tank after the vaporization operation is performed using the liquid nitrogen supplied from the demand source. Efficiency can be improved by shortening the operating time needed to meet the purity of liquid nitrogen to meet the needs of the customer.

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a view illustrating a liquefied gas storage vessel storing liquefied natural gas and liquid nitrogen in a storage tank while operating between a source of natural gas and a destination of natural gas according to an exemplary embodiment of the present invention.
Figure 2 uses the nitrogen gas supplied from the source of the liquefied natural gas remaining in the first storage tank of the liquefied gas storage vessel shown in Figure 1 after the unloading operation at the demand source or the nitrogen gas vaporized liquid nitrogen supplied from the demand source And vaporize, and compress and heat the mixed gas of natural gas and nitrogen gas generated in the first storage tank to be used for vaporizing the second storage tank.
FIG. 3 illustrates another example of compressing a mixture of natural gas and mixed gas generated by a second storage tank vaporization operation through a first compressor of FIG.
FIG. 4 illustrates a cooling operation of the first storage tank by supplying liquid nitrogen to the first storage tank from a demand source during the vaporization of the second storage tank of FIG. 2.
5 is a flowchart illustrating a method of operating a liquefied gas storage vessel according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments introduced below are provided as an example to sufficiently convey the spirit of the present invention to those skilled in the art to which the present invention pertains. The present invention is not limited to the embodiments described below and may be embodied in other forms. Parts not related to the description are omitted in the drawings in order to clearly describe the present invention, in the drawings, the width, length, thickness, etc. of the components may be exaggerated for convenience. Like numbers refer to like elements throughout.

1 is a view illustrating a liquefied gas storage vessel storing liquefied natural gas and liquid nitrogen in a storage tank while operating between a source of natural gas and a demand source of natural gas according to an exemplary embodiment of the present invention.

1, a liquefied gas storage vessel (100, hereinafter referred to as "ship") according to an embodiment of the present invention is supplied with liquefied natural gas (LNG) from the source (1) of natural gas storage tank 110 After storing to the demand destination (2), the liquefied natural gas (LNG) stored in the storage tank 110 is unloaded from the demand destination (2), the liquid supplied to the empty storage tank 110 from the demand destination (2) Nitrogen (LN2) can be stored and transported back to the source of natural gas (1).

Here, the storage tank 110 is installed in a plurality of hulls, it may be made of a membrane (Membrane) type of heat-insulated treatment to minimize the generation of boil-off gas by external heat intrusion. The storage tank 110 may receive and store liquefied natural gas from the source 1 of natural gas, and receive and store liquid nitrogen from the demand source 2. That is, the vessel 100 may alternately store liquefied natural gas and liquid nitrogen in the storage tank 110 while reciprocating between the natural gas producing region 1 and the demand destination 2. The storage tank 110 may include a delivery pump (not shown) and a pump tower (not shown) for sending the liquefied gas stored therein to the outside. For reference, the fuel tank 110a provided in the vessel 100 always stores liquefied natural gas as a supply fuel of the vessel 100.

Through this, the vessel can unload the liquefied natural gas to the demand place, and when the voyage to the natural gas production area for the transportation of the liquefied natural gas, it is possible to solve the problem that the storage tank is empty and operated in an empty state.

Figure 2 uses the nitrogen gas supplied from the source of the liquefied natural gas remaining in the first storage tank of the liquefied gas storage vessel shown in Figure 1 after the unloading operation at the demand source or the nitrogen gas vaporized liquid nitrogen supplied from the demand source And vaporize, and compress and heat the mixed gas of natural gas and nitrogen gas generated in the first storage tank to be used for vaporization of the second storage tank. Hereinafter, for convenience of description, the storage tank 110 will be described by dividing the first storage tank 111 and the second storage tank 112.

2, the liquefied gas storage vessel 100 according to an embodiment of the present invention is to unload the liquefied natural gas supplied from the origin of natural gas (1, see FIG. 1) at the demand destination of natural gas (2), After unloading, a process for storing the liquid nitrogen in the storage tank (110).

The liquefied gas storage vessel 100 according to the embodiment of the present invention, after unloading the liquefied natural gas, nitrogen gas or demand source 2 supplied from the demand source 2 to the first storage tank 111 of at least one of the storage tanks 110. The nitrogen gas supply line (L1) for supplying the nitrogen gas vaporized the liquid nitrogen supplied from the) to vaporize the liquefied natural gas remaining in the first storage tank 111 after unloading, and generated by the above-mentioned vaporization operation A first compression unit 120 for receiving and compressing a mixed gas of natural gas and nitrogen gas in the first storage tank 111 and a heating unit for heating the mixed gas compressed by the first compression unit 120 ( 130 and the liquefied natural gas remaining in the second storage tank 112 after unloading by supplying the mixed gas heated by the heating unit 130 to at least one second storage tank 112 of the storage tank 110. It includes a heated mixed gas supply line (L2) to be vaporized.

In addition, the liquefied gas storage vessel 100 is compressed by receiving a mixture of the natural gas and the mixed gas in the second storage tank 112 generated by the mixed gas heated and supplied by the heating unit 130 described above. The second compression unit 140 and the first discharge line (L3) for discharging the mixture compressed by the second compression unit 140 toward the demand destination (2).

In FIG. 2, the above-described vaporization operation and the related configuration are applied to the first storage tank 111 and the second storage tank 112 for clarity, but this configuration may be applied to other storage tanks 110. Do. Hereinafter, each component is demonstrated concretely.

Nitrogen gas supply line (L1) is one or more first storage tank 111 is completed to unload the liquefied natural gas by pumping the nitrogen gas supplied from the demand source (2) or the nitrogen gas vaporized liquid nitrogen supplied from the demand source (2) by the pump ), The liquefied natural gas remaining in the first storage tank 111 that can not be unloaded by the pump to be vaporized. In this case, nitrogen gas may be simultaneously supplied to the plurality of first storage tanks 111 or nitrogen gas may be supplied to any one of the first storage tanks 111.

Here, although not shown, the nitrogen gas supplied from the demand source 2 for the vaporization of the first storage tank 111 is heated to a predetermined temperature by a heating means provided in the nitrogen gas supply line L1 or the demand destination 2. Then it may be supplied to the first storage tank 111.

In addition, when the liquid nitrogen is supplied from the demand source (2) for the vaporization of the first storage tank 111, although not shown, the liquid nitrogen by the vaporization means (not shown) provided in the nitrogen gas supply line (L1). After vaporizing with nitrogen gas, it may be supplied to the first storage tank 111. In this case, a vaporization means (not shown) may be provided to the demand destination 2 to vaporize the above-described liquid nitrogen with nitrogen gas and then supply the first nitrogen gas to the first storage tank 111 through the nitrogen gas supply line L1. Hereinafter, for convenience of description, the nitrogen gas is supplied from the demand source 2 for vaporization of the first storage tank 111 by way of example.

As described above, when the remaining liquefied natural gas of the first storage tank 111 is vaporized by the nitrogen gas supplied from the demand source 2, natural gas is generated, which is supplied by the mixed gas mixed with the nitrogen gas to supply the heat mixed gas. It is supplied to the first compression unit 120 through the line (L2).

The first compression unit 120 compresses the corresponding mixed gas on the basis of a preset pressure, and sends the compressed mixed gas to the heating unit 130 through the heating mixed gas supply line L2.

The heating unit 130 includes, for example, a heater and heats the mixed gas compressed by the first compression unit 120 to the one or more second storage tanks 112 through the heating mixed gas supply line L2. Supply.

Natural gas is generated when the remaining liquefied natural gas of the second storage tank 112 is vaporized by the heated mixed gas supplied through the heat mixed gas supply line (L2), which is a mixture mixed with the above-described mixed gas. It is discharged to the demand destination 2 via the second compression unit 140 through the first discharge line (L3). This is because the mixture contains a large amount of natural gas, it is preferable to discharge through the first discharge line (L3) in order to store the liquid nitrogen of high purity in the second storage tank (112).

The second compression unit 140 may compress the above-described mixture according to the pressure required by the customer 2.

As such, the nitrogen gas used for the liquefied natural gas vaporization of the first storage tank 111 is compressed and heated together with the natural gas generated in the first storage tank 111 to liquefy the natural gas of the second storage tank 112. By reusing the vaporization, the amount of nitrogen gas supplied from the demand source 2 can be reduced.

Referring to FIG. 3, as another example, the liquefied gas storage vessel 100 is connected to the front end of the first compression unit 120 of the heating mixed gas supply line L2, and is heated and supplied by the heating unit 130 described above. A second discharge line L4 for supplying and compressing a mixture of natural gas and mixed gas in the second storage tank 112 generated by the mixed gas to the first compression unit 120 and a heated mixed gas supply line ( It may include a branch line (L5) branched from between the first compression unit 120 and the heating unit 130 of L2 and discharges the mixture compressed by the first compression unit 120 toward the demand destination (2). Through this, it is not necessary to separately provide the second compression unit 140 described above.

On the other hand, referring to Figure 4, the liquefied gas storage vessel 100 is a spray line (L6) connecting the storage tank 110 and the demand destination (2), and the vaporization treatment operation for the remaining liquefied natural gas inside after unloading The nozzle unit 150 for spraying and cooling the liquid nitrogen supplied from the demand source 2 through the spray line L6 may be provided inside the completed storage tank 110.

In FIG. 4, the spray line L6 is configured to connect the first storage tank 111 and the demand destination 2 to facilitate understanding, and a nozzle unit (6) at the end of the spray line L6 inside the first storage tank 111. Although 150 has been described as an example, such a configuration may be configured in all other storage tanks 110.

That is, as described above, the cooling operation may be performed by the liquid nitrogen supplied from the demand source 2 for the storage tank 110 in which the vaporization operation is completed.

At this time, for example, during the cooling operation for the inner wall of the first storage tank 111, if the vaporization operation for the liquefied natural gas still remaining in the second storage tank 112 after unloading, the cooling operation is made The gas generated in the first storage tank 111 is sent to the first compression unit 120 and the heating unit 130 through the heat mixed gas supply line L2, compressed and heated, and supplied to the second storage tank 112. Thus, the second storage tank 112 can be used for the vaporization operation.

At this time, since the gas generated in the first storage tank 111 in which the cooling operation is performed includes a large amount of nitrogen, it can be effectively used for the vaporization of the second storage tank 112, and the nitrogen supplied from the demand source 2 through this. The amount of gas can be reduced. In addition, it is possible to reduce the content of natural gas contained in the gas of the second storage tank 112, increase the content of nitrogen gas, thereby increasing the purity of the liquid nitrogen to be shipped later.

In addition, when the vaporization work for the liquefied natural gas remaining in the second storage tank 112 is completed, the cooling operation for the second storage tank 112 together with the first storage tank 111 may be performed at the same time.

After the cooling operation is completed, the liquid nitrogen supplied from the demand source 2 is filled in the first storage tank 111.

Hereinafter, a method of operating the liquefied gas storage vessel 100 will be described with reference to FIG. 5 based on the above description.

First, as shown in FIG. 2, the liquefied natural gas supplied from the producing region 1 of natural gas is supplied to the first storage tank 111 of at least one of the storage tanks 110 unloaded from the demand source 2 of natural gas. The nitrogen gas supplied from (2) is supplied to vaporize the liquefied natural gas remaining in the first storage tank 111 after unloading (S1). Although not shown, the nitrogen gas supplied from the demand source 2 may be supplied into the first storage tank 111 in a state of being heated to a temperature set by a heating means.

In another example, the liquefied natural gas remaining in the first storage tank 111 may be vaporized by supplying nitrogen gas obtained by evaporating the liquid nitrogen supplied from the demand source 2. In this case, although not shown, vaporization means for vaporizing the liquid nitrogen supplied from the demand source 2 may be provided.

Next, by compressing and heating a mixed gas of natural gas and nitrogen gas in the first storage tank 111 generated by the above-described vaporization operation and supplying it to one or more second storage tanks 112, the second storage after unloading The liquefied natural gas remaining in the tank 112 is vaporized (S2). Here, as shown in FIG. 2, when the remaining liquefied natural gas of the second storage tank 112 is vaporized, natural gas is generated, which is a mixture mixed with the above-described mixed gas through the first discharge line L3. Via the second compression unit 140 may be discharged to the demand destination (2). In another embodiment, as shown in FIG. 3, a mixture of natural gas and mixed gas generated in the second storage tank 112 is compressed through the first compression unit 120 through the second discharge line L4. It may be sent to the demand source (2) through the branch line (L5).

Next, as shown in FIG. 4, the liquid nitrogen supplied from the demand source 2 is injected into the first storage tank 111 in which the vaporization operation is completed to cool the first storage tank 111 (S3).

Next, when the vaporization operation for the liquefied natural gas remaining in the second storage tank 112 after the unloading is being carried out, the heat generated gas supply line (L2) in the gas generated inside the first storage tank 111 cooling operation is performed By sending the first compression unit 120 and the heating unit 130 through the compression and heating, it is supplied to the second storage tank 112 to be used for the vaporization of the second storage tank 112 (S4). ).

Subsequently, when the vaporization operation for the liquefied natural gas remaining in the second storage tank 112 is completed, the cooling operation may be performed like the first storage tank 111 described above.

Next, the first storage tank 111 in which the cooling operation is completed is supplied with the liquid nitrogen from the demand destination (2) and stored (S5). In this case, when the cooling operation for the second storage tank 112 is completed, the liquid nitrogen is supplied and stored from the demand source 2 like the first storage tank 111.

In the above, specific embodiments have been illustrated and described. However, the present invention is not limited only to the above-described embodiments, and those skilled in the art to which the present invention pertains can variously change variously without departing from the gist of the technical idea of the invention described in the claims below. Could be.

1: Natural gas producer 2: Natural gas demand source
110: storage tank 110a: fuel tank
120: first compression unit 130: heating unit
140: second compression unit 150: nozzle unit
L1: nitrogen gas supply line L2: heated mixed gas supply line
L3: first discharge line L4: second discharge line
L5: Branch Line L6: Spray Line

Claims (7)

Supplying nitrogen gas supplied from the source or nitrogen gas vaporized from the source of liquid to the first storage tank of one or more storage tanks in which the liquefied natural gas supplied from the source of natural gas is unloaded from the source of natural gas. A nitrogen gas supply line for vaporizing the liquefied natural gas remaining in the first storage tank after unloading;
A first compression unit receiving and compressing a mixed gas of natural gas and nitrogen gas in the first storage tank generated by the vaporization operation;
A heating unit heating the compressed mixed gas; And
Liquefied gas storage vessel including; a heated mixed gas supply line for supplying the heated mixed gas to at least one second storage tank of the storage tank, the liquefied natural gas remaining in the second storage tank to vaporize after unloading . The method of claim 1,
A second compression unit configured to receive and compress a mixture of the natural gas and the mixed gas in the second storage tank generated by the heated mixed gas;
A liquefied gas storage vessel further comprising a first discharge line for sending the compressed mixture toward the demand destination. The method of claim 1,
A second discharge line for supplying and compressing a mixture of the natural gas and the mixed gas in the second storage tank generated by the heated mixed gas to the first compression unit;
And a branching line branched between the first compression unit and the heating unit of the heating mixed gas supply line to direct the compressed mixture toward the demand destination. The method of claim 1,
A spray line connecting the storage tank and the demand destination;
And a nozzle unit for injecting and cooling the liquid nitrogen supplied from the demand source through the spray line to the inside of the storage tank in which the vaporization process for the remaining liquefied natural gas is completed after unloading. In the method of operating a liquefied gas storage vessel according to any one of claims 1 to 4,
(a) nitrogen gas supplied from the source or liquid nitrogen supplied from the source into one or more first storage tanks of the liquefied natural gas supplied from the source of the natural gas from the source of natural gas; Supplying a gas to vaporize the liquefied natural gas remaining in the first storage tank after unloading;
(b) compressing and heating a mixed gas of natural gas and nitrogen gas in the first storage tank generated by the vaporization operation and supplying it to one or more second storage tanks to liquefy remaining in the second storage tank after unloading. Vaporizing natural gas; And
(c) cooling the first storage tank by injecting liquid nitrogen supplied from the demand source into the first storage tank, thereby operating a liquefied gas storage vessel. The method of claim 5,
After the step (b), the operation of the liquefied gas storage vessel further comprises the step of receiving the compressed mixture of the natural gas and the mixed gas in the second storage tank generated by the heated mixed gas to the demand destination Way. The method of claim 5,
After the step (c), when the vaporization operation for the liquefied natural gas remaining in the second storage tank is being performed, the second storage tank by compressing and heating the gas generated in the first storage tank in which the cooling operation is performed. Supplying to, the operation method of the liquefied gas storage vessel further comprising the step of being used for the vaporization operation of the second storage tank.

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