KR101224918B1 - Lng loading pipe device and loading method using the same - Google Patents

Abstract

Disclosed are a piping system for loading liquefied natural gas and a shipping method using the same. One embodiment of the present invention has a vertical pipe form capable of heat transfer, and the dropping pipe disposed inside the cargo hold to fill the liquefied natural gas,
The diaphragm member is provided inside the end of the dripping pipe, and when the upper row of the dripping pipe is transferred to the lower side and the height of the liquid column of the liquefied natural gas is increased, the diaphragm member gradually reduces the volume and gradually widens the flow path of the dripping pipe. It includes.

Description

LNG loading piping system and loading method using same {LNG LOADING PIPE DEVICE AND LOADING METHOD USING THE SAME}

The present invention relates to liquefied natural gas shipment, and more particularly to a liquefied natural gas loading piping device and a shipping method using the same.

As is well known, liquefied natural gas (LNG) refers to a colorless, transparent cryogenic liquid whose natural gas, which contains methane as its main component, is cooled to minus 163 ° C and its volume is reduced to approximately one hundredth.

As such liquefied natural gas has emerged as an energy resource, an efficient transportation method that can transport a large amount from the production base to the demand site has been considered in order to use this gas as energy. LNG carriers that can be transported by air have emerged.

By the way, the LNG carrier should be equipped with a cargo tank (cargo) for storing and storing the liquefied natural gas liquefied in the cryogenic state, the liquefied natural gas has a boiling temperature of about 163 ℃ below zero In order to safely store and store it, the cargo hold for storing and storing it should be made of materials that can withstand cryogenic temperatures, such as aluminum steel, stainless steel, 35% nickel steel, etc., and is resistant to other thermal stresses and heat shrinkage, It should be designed to prevent intrusion.

Accordingly, the cargo hold is made of, for example, spherical type (mepherical type), membrane type (membrane type), etc., the membrane type cargo hold has a larger loading capacity than the old type cargo hold, it is the most widely used because of the easy production. have.

Liquefied natural gas carriers, floating production storage vessels or floating facilities according to the prior art is a cargo hold liquid line for loading or unloading LNG in the cargo hold 100, as shown in FIG. It has a pipe network 101 including.

In addition, the conventional vessel or floating equipment is connected to one side of the pipe network 101, the unloading column 103 having a pump 104 to unload the liquefied natural gas to the outside of the cargo hold 100, and the pipe network ( It is connected to the other side of the 101 is provided with a loading column 102, which is a vertical pipe for loading the liquefied natural gas into the cargo hold 100. The loading column 102 is coupled vertically downward from the pipe network 101 and extends toward the bottom of the interior of the cargo hold 100.

Here, in the case of the conventional vessel or floating equipment, the pipe network 101 or the loading column 102 for the shipment of the liquefied natural gas in the cargo hold 100 is not provided with a device for adjusting the pressure inside the pipe or column. .

In addition, since the exit end of the loading column 102 connected to the pipe network 101 and the liquefied natural gas in the cargo hold 100 directly contact each other, the pressure inside the pipe or column affects the height of the liquid column of the liquefied natural gas in the cargo hold 100. Will receive.

In the case of the loading column 102, which is a vertical pipe of the piping network 101 for shipment, when the liquid column of the liquefied natural gas in the cargo hold 100 is low, the loading column 102 by the change in the static pressure according to the liquid column height and the acceleration of the flow The probability of the occurrence of bubbles in the cavity increases considerably.

In this case, the liquefied natural gas may be transported in the form of a two-phase flow including bubbles rather than a single phase flow.

In this case, phenomena that adversely affect the pipe network 101 system such as cavitation or flashing may occur due to pressure fluctuations in the pipe network 101.

These phenomena are frequently seen in system operation such as transferring, circulation, mode change, etc., when the liquid column height of the liquefied natural gas in the cargo hold 100 is low.

This phenomenon may also occur during initial shipment of the cargo hold 100 into the storage tank, thus leading to more excessive gas generation.

For example, during the initial shipment according to the prior art, the liquefied natural gas flowing along the pipe network 101 at the top of the cargo hold 100 is accelerated by gravity when it reaches the inner top of the loading column 102, the loading column 102 It flows rapidly downward along.

Because of this, the pressure of the liquefied natural gas in the upper portion inside the loading column 102 is reduced to below the atmospheric pressure, and eventually a large amount of bubbles may be generated and increased in the liquefied natural gas.

Since the bubbles generated or increased in this way are exposed in the cargo hold 100 as it is, since a lot of gaseous gases are generated in the cargo hold 100 at the time of initial shipment, the pressure of the cargo hold 100 is increased, so that the equipment for the treatment of a separate gas gas is increased. Installation or operating costs may be required or adversely affect LNG management and operation.

Accordingly, according to one aspect of the present embodiment, by installing a diaphragm member at the lower end of the dropping pipe, opening and closing of the flow path of the dropping pipe end by the temperature changed as the liquefied natural gas is filled in the cargo hold By adjusting the amount, it is possible to increase the pressure inside the pipe network, including the drip pipe during the initial shipment to more than atmospheric pressure to prevent the generation of steam.

An embodiment of the present invention has a vertical pipe form capable of heat transfer, the dropping pipe disposed inside the cargo hold to fill the liquefied natural gas, and provided inside the end of the dropping pipe, the heat of the dropping pipe is transferred, When the liquid column height of the liquefied natural gas is raised, the liquefied natural gas loading piping device including a diaphragm member which gradually decreases the volume and gradually widens the flow path of the dropping pipe can be provided.

In addition, the diaphragm member may be filled with a working fluid including natural gas or methanol, and may include a body part provided in pairs at the end of the dropping pipe.

In addition, the diaphragm member may be formed so that heat is continuously transmitted through the dropping pipe to prevent a sudden volume change of the diaphragm member.

In addition, the embodiment of the present invention is the step of increasing the fluid volume of the diaphragm member in accordance with the rise of the temperature of the cargo hold, the step of reducing the member side flow path according to the expansion of the diaphragm member, and liquefied natural gas is shipped to the cargo hold Gradually decreasing the fluid volume of the diaphragm member according to the temperature drop of the cargo hold; gradually expanding the member-side flow path according to the reduction of the diaphragm member; and after completion of the LNG shipment, the diaphragm member is It is possible to provide a shipping method using a liquefied natural gas loading piping device comprising the step of restoring the original reduced form.

In addition, when the LNG is shipped to the cargo hold, as the diaphragm member is expanded, the internal pressure of the pipe network and the dropping pipe to which the liquefied natural gas is supplied may be increased above atmospheric pressure.

In addition, the diaphragm member may be continuously transferred to the heat through the dropping pipe to prevent a sudden volume change of the diaphragm member.

According to the present invention, when the cargo hold temperature is relatively high before shipment, the diaphragm member installed at the lower end of the dropping pipe can be expanded to reduce the size of the flow path of the dropping pipe. And as the filling through the drip pipe, it is possible to naturally have a pressure above atmospheric pressure in the drip pipe and the pipe network.

At this time, since the pressure transmitted from the land base for the shipment of liquefied natural gas takes into account the pressure when the liquefied natural gas fills the cargo hold within a predetermined range, it is not necessary to maintain the pressure in the tube at this time. It is possible to prevent liquefied natural gas from converting into a two-phase flow in the drip pipe without affecting other effects.

Therefore, the present embodiment can contribute a lot to alleviate side effects due to bubbles that may occur in the reduction of the amount of gas generated in the cargo hold and the circulation or liquefied natural gas transfer generated during cargo loading.

1 is a view illustrating a LNG cargo hold having a conventional loading column.
2 is a view illustrating a LNG cargo hold having a dropping pipe having a diaphragm member according to an embodiment of the present invention.
3 is a view schematically illustrating that the diaphragm member installed at the end of the dropping pipe is adjusted according to an embodiment of the present invention.
4 is a flowchart illustrating a process of loading liquefied natural gas using a diaphragm member installed at an end of a dropping pipe 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. In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

2 is a view illustrating a LNG cargo hold having a dropping pipe having a diaphragm member according to an embodiment of the present invention.

Referring to FIG. 2, a shipping piping device for loading liquefied natural gas into a LNG storage 200 according to the present embodiment is connected to a liquid main head 201 of a pipe network of the cargo storage 200 and is stored inside the cargo storage 200. It may include a dropping pipe 202 that refers to the disposed portion, and a diaphragm member 206 provided at the lower end of the dropping pipe 202.

The dropping pipe 202 may include a heat pipe line in the form of a vertical pipe through which heat is transferred, and may be disposed inside the LNG carrier 200.

The liquefied natural gas may be introduced into the cargo hold 200 through a pipe network of a ship or a floating facility and a dropping pipe 202 disposed inside the cargo hold 200 through an inter-connecting device provided at a terminal such as a shipping port. .

Here, the dropping pipe 202 may serve to transfer the upper heat of the cargo hold 200 to the bottom.

Through this, the dropping pipe 202 may continuously transmit heat to the diaphragm member 206 to prevent rapid volume change of the diaphragm constituting it.

In addition, the diaphragm member 206 is loaded with a structure filled with a working fluid (for example, natural gas (NG) and methanol) having a temperature characteristic similar to that of liquefied natural gas therein. It can be arranged in pairs to adjust the size of the flow path or the pipe bore size when liquefied natural gas is shipped.

That is, when the cargo hold 200 is empty before the shipment of the liquefied natural gas, the temperature of the cargo hold 200 may increase.

In this case, due to the expansion of the working fluid inside the diaphragm member 206 due to the increase in temperature, the diaphragm member 206 is expanded in the originally reduced state, thereby reducing the diameter of the flow path at the end side of the dripping pipe 202 to be smaller. I can let you.

Then, when liquefied natural gas is shipped, the pressure in the pipe network, including the dropping pipe 202 may be increased above atmospheric pressure as the flow path is reduced.

As the liquefied natural gas is continuously loaded, the height of the liquid column may increase in the cargo hold 200, and the temperature of the cargo hold 200 may decrease.

At this time, since the upper portion of the dropping pipe 202 does not directly contact the liquefied natural gas, heat of the upper side of the dropping pipe 202 may continue to be transferred to the lower side of the dropping pipe 202.

As a result, the expanded state of the diaphragm member 206 is not abruptly reduced, but can be gradually reduced as the liquid column height rises with the internal temperature drop of the cargo hold 200.

That is, the volume reduction of the working fluid inside the diaphragm member 206 may be made gradually during the filling of the liquefied natural gas.

Then, when the liquefied natural gas is filled in the cargo hold 200, the diaphragm member 206 is returned to its original shape, the flow path size may also be the original size.

Through this process, at the beginning of the LNG loading, the pressure inside the dropping pipe 202 may be raised above atmospheric pressure.

In addition, when the filling is continuously made, as the height of the liquid column in the cargo hold 200 increases, the pressure to act on the drip pipe 202 is increased, as a result, the pressure inside the drip pipe 202 is continuously maintained above atmospheric pressure Can be.

That is, the diaphragm member 206 may be used for the purpose of preventing the internal pressure of the pipe network or the dropping pipe 202 below the atmospheric pressure because the height of the liquid column in the cargo tank 200 is very low at the beginning of liquefied natural gas shipment.

3 is a view schematically illustrating that the diaphragm member installed at the end of the shipping pipe is adjusted according to an embodiment of the present invention.

Referring to FIG. 3, the diaphragm member 206 has an enlarged body portion 206a, 206b or a reduced body portion provided in pairs at the end of the dropping pipe 202 in a structure filled with the aforementioned working fluid. 206a ', 206b'.

If liquefied natural gas is before being loaded into the cargo hold, the temperature of the cargo hold can be kept relatively higher than when storing the liquefied natural gas.

As shown in the left side of FIG. 3, the diaphragm member 206 may have expansion body portions 206a, 206b.

Thereafter, the liquefied natural gas may start filling the cargo hold, so that the liquefied natural gas and the diaphragm member 206 may directly contact each other.

The diaphragm member 206 may not immediately shrink because heat can be continuously transmitted from the upper portion of the dripping pipe 202 having a relatively high temperature.

In addition, the liquefied natural gas shipped to the liquefied natural gas cargo hold may initially have a very low liquid column height, and thus the volume of the one body portion 206a and the other body portion 206b may be maintained in an expanded state. In addition, while making the flow path of the dripping pipe 202 small, the internal pressure of the dripping pipe 202 and the pipe network can be increased.

Liquefied natural gas loaded into LNG cargo hold may have higher and higher liquid column height, and the temperature inside the cargo hold may gradually decrease.

In such a case, as shown in the right side of FIG. 3, the diaphragm member 206 does not immediately contract, but gradually contracts according to the rate of receiving heat from the upper portion of the dropping pipe 202, thereby reducing the body parts 206a ′ and 206b. Can be

In particular, as the liquid column height of the cargo hold increases, the flow path of the dripping pipe 202 gradually increases as the volume of the diaphragm member decreases, but due to the water head pressure of the liquefied natural gas at the end of the dripping pipe 202 increased. As a result, the internal pressure of the dropping pipe 202 and the pipe network can also be continuously maintained above atmospheric pressure.

Hereinafter, a shipping method using the liquefied natural gas loading piping device according to the present embodiment will be described.

4 is a flowchart illustrating a process of loading liquefied natural gas using a diaphragm member installed at an end portion of a shipping pipe according to an embodiment of the present invention.

Referring to FIG. 4, the shape of the original diaphragm member is reduced in a substantially flat state, and the size of the original diaphragm member side flow path may also be formed in a state similar to that of the shipping pipe.

In this state, when the cargo hold is empty before the LNG shipment, as the temperature of the cargo hold rises, the fluid volume of the diaphragm member installed at the lower end of the dropping pipe of the cargo hold may increase (S402). Here, the fluid of the diaphragm member may refer to the aforementioned working fluid.

In this case, the member-side flow path may be reduced by causing expansion of the diaphragm member (S404).

In this state, the cargo hold shipment of liquefied natural gas can be started. That is, after the liquefied natural gas is transferred through the pipe network and the dropping pipe through the line connecting device provided in the terminal of the loading port, it may be introduced into the cargo hold through the inner diameter of the diaphragm member of the lower end of the dropping pipe (S406).

In particular, since the diaphragm member side flow path is reduced, the pressure of the liquefied natural gas in the pipe network and the dripping pipe can be increased above atmospheric pressure even at the beginning of liquefied natural gas shipment, and thus, the generation of bubbles of the liquefied natural gas can be suppressed.

When the liquefied natural gas starts to be filled in the cargo hold, the fluid volume of the diaphragm member may gradually decrease as the cargo hold temperature decreases (S408).

 This decrease in fluid volume increases gradually during the filling of the LNG into the cargo hold. Accordingly, the diaphragm member is reduced so that the member side flow path may be gradually enlarged (S410).

After the LNG shipment, the diaphragm member may be restored to its original reduced form (S412).

In particular, as the liquid column height of the cargo hold is increased, the pressure inside the cargo hold is increased, so that the increased pressure inside the cargo hold is acted on the inside of the dropping pipe 202 even though the flow path of the dripping pipe 202 is gradually increased. As a result, the internal pressure of the dropping pipe 202 and the pipe network can also be maintained at an appropriate pressure level that can continuously suppress the generation of steam above atmospheric pressure.

In the above description, various embodiments of the present invention have been described and described, but the present invention is not necessarily limited thereto, and a person having ordinary skill in the art to which the present invention pertains can make various changes without departing from the technical spirit of the present invention. It will be readily appreciated that branch substitutions, modifications and variations are possible.

200: cargo hold 201: liquid main head
202: dripping piping 206: diaphragm member

Claims (6)

A dropping pipe having a vertical pipe shape capable of heat transfer and disposed inside the cargo hold to fill liquefied natural gas;
Is provided inside the end of the dropping pipe, when the heat of the dropping pipe is transferred, when the liquid column height of the liquefied natural gas is increased, the volume is gradually reduced to include a diaphragm member to gradually widen the flow path of the dropping pipe
LNG loading piping system.
The method of claim 1,
The diaphragm member
It is filled with a working fluid containing natural gas or methanol and comprises a body portion provided in pairs at the end of the dropping pipe
LNG loading piping system.
3. The method according to claim 1 or 2,
The diaphragm member
Heat is continuously transmitted through the dropping pipe so as to prevent a sudden volume change of the diaphragm member.
LNG loading piping system.
Increasing the fluid volume of the diaphragm member as the temperature of the cargo hold increases,
Reducing the member-side flow path according to the expansion of the diaphragm member;
Liquefied natural gas is shipped to the cargo hold;
Gradually decreasing the fluid volume of the diaphragm member as the temperature of the cargo hold decreases;
Gradually expanding the member-side flow path according to the reduction of the diaphragm member;
Restoring the diaphragm member to its original reduced form after completion of LNG shipment.
Shipment method using LNG gas piping system.
The method of claim 4, wherein
In the step where the liquefied natural gas is shipped to the cargo hold
According to the expansion of the diaphragm member, the internal pressure of the pipe network and the dropping pipe to which the liquefied natural gas is supplied may be increased above atmospheric pressure.
Shipment method using LNG gas piping system.
The method according to claim 4 or 5,
The diaphragm member
Heat is continuously transmitted through the dropping pipe to prevent a sudden volume change of the diaphragm member.
Shipment method using LNG gas piping system.

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