JP2003065496A - Method of transporting natural gas by ship and natural gas carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of transporting natural gas by a ship with improved transporting efficiency. SOLUTION: This method of transporting the natural gas in a pelletized state by a ship comprises a process (Fig. 7 (1)) for receiving the natural gas at a loading place 2, pelletizing the natural gas on a natural gas carrier 6, and loading the natural gas in a cargo hold 11a, a process (Fig. 7(2)) for transporting the pellets loaded in the cargo hold 11a while cooling the same at a predetermined temperature under a predetermined pressure, and a process (Fig. 7(3)) for heating the natural gas by a heat source device 12 at an unloading place 7 to decompose the pelletized natural gas, and charging the natural gas in a storage tank 8a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a natural gas transportation method and a natural gas transportation ship by a ship that hydrates (slurries or pelletizes) natural gas for transportation.

[0002]

2. Description of the Related Art Conventionally, a natural gas transportation method by a ship is a method of liquefying natural gas at a loading place, loading the liquefied natural gas on a ship for transportation, and unloading the liquefied natural gas from the ship at an unloading place. Met. FIG. 11 is a diagram for explaining a conventional natural gas transportation method by a ship.
11 (1) shows the state at the loading place, FIG. 11 (2) shows the state during transportation, and FIG. 11 (3) shows the state at the unloading place. As shown in FIG. 11 (1), in the loading land 101, the gaseous natural gas sent from the natural gas mining land is liquefied and accumulated in the storage tank 102.

[0003]

[Table 1]

The conditions for producing and storing the liquefaction at this time are, as described in the section of the prior art of Table 1, the state of natural gas in the liquid phase, the temperature below minus 162 [° C.], and the pressure about. Cooling is a means for keeping the liquid natural gas at 0.025 [MPa] or less. When transporting the liquefied natural gas in the storage tank 102 to the place of consumption, the procedure was as follows.

First, a liquefied natural gas (LNG) ship 103 is berthed at a loading point 101, and the storage tank 102 and LNG are connected to each other.
The cargo tank 104 of the ship 103 is connected with the liquid line 105 and the gas line 106, and the L side of the liquid line 105 on the land side is connected.
Cargo tank 1 of LNG carrier 103 by NG pump 107
Liquefied natural gas was loaded on 04, and the decomposed natural gas was returned to the storage tank 102 of the loading place 101 by the compressor 108 of the gas line 106 (see FIG. 11 (1)). The cargo conditions are listed in the prior art cargo column of Table 1.

[0006] Next, the LNG ship 103 is
To the landing site 111 (see FIG. 11 (2)).
The shipping conditions are listed in the Prior Art Shipping section of Table 1. Next, the LNG carrier 103 is docked at the landing site 111, and the cargo tank 104 and the landing site 111 of the LNG carrier 103 are docked.
The storage tank 112 of No. 1 is connected with the liquid line 113 and the gas line 114, and the liquefied natural gas is unloaded to the storage tank 112 of the landing site 111 by the ship side LNG pump 115 of the liquid line 113, and unloaded by the compressor 116 of the gas line 114. LNG carrier 10 from the storage tank 112 of the land 111
The decomposed natural gas was returned to the cargo tank 104 of No. 3 (see FIG. 11 (3)). The unloading conditions are described in the column of unloading of the related art in Table 1.

[0007]

According to the above-mentioned conventional natural gas transportation method by ship, the natural gas is boiled off due to the relationship between pressure and temperature because it is loaded or sailed in the state of liquefied natural gas. Sometimes. In particular, when liquefied natural gas is loaded from the storage tank 102 to the LNG carrier 103 at the loading place, the liquefied natural gas is boiled off to some extent and is also boiled off during the cargo voyage, and a predetermined amount of liquefied natural gas is used for the ballast voyage. Had to be left on the LNG carrier 103, which resulted in the loss of a large amount of liquefied natural gas and the poor transport efficiency. Further, it is necessary to consider the refrigerating equipment for achieving an extremely low temperature, the material for the refrigerating equipment, and the like, resulting in a drawback that the equipment cost is increased. The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a natural gas transportation method and a natural gas transportation vessel by a ship with improved transportation efficiency.

[0008]

In order to achieve the above object, a method for transporting natural gas by a ship according to the invention of claim 1 is a method of pelletizing natural gas and transporting the natural gas by ship. Receiving natural gas at the ground, pelletizing it on a ship and loading it into a cargo hold; transporting the loaded pellets while cooling it at a predetermined temperature under a predetermined pressure; heating and pelleting at the landing place And discharging the liquefied natural gas to unload it. In order to achieve the above object, claim 2
A natural gas transportation method by a ship according to the invention described is a method of transporting natural gas into a slurry by ship,
Loading slurry natural gas into the cargo hold at the loading place, transporting the loaded slurry natural gas while cooling it at a predetermined temperature under a predetermined pressure, and slurry natural gas at the landing place And a step of unloading. In order to achieve the above purpose,
A method for transporting natural gas by a ship according to the invention of claim 3 is a method of loading the slurry-like natural gas into a ship and pelletizing and transporting the natural gas, and loading the slurry-like natural gas into a cargo hold at a loading point, The slurry natural gas loaded in the cargo hold in the above step is drained by a drainage pump, and cooled at a predetermined temperature under a predetermined pressure to pelletize the natural gas, and the natural pelletized in the step. It is characterized by including a step of transporting the gas while cooling it at a predetermined temperature under a predetermined pressure, and a step of decomposing and unloading the pelletized natural gas by heating at a landing site. . In order to achieve the above object, the natural gas transport ship according to the invention of claim 4 is a natural gas transport ship capable of pelletizing and transporting natural gas, the natural gas being pelletized on a receiving ship, and a cargo hold. A natural gas pellet manufacturing device to be put into a container, a cargo hold having a strength equal to or higher than a predetermined pressure and being heat-insulated, and the cargo hold being cooled at a predetermined temperature during transportation and being unloaded at a landing place. Is
It is provided with a heat source device capable of decomposing the heated and pelletized natural gas, and a cargo handling means for sending the decomposed natural gas to the landing-side facility when unloading. In order to achieve the above object, a natural gas transport ship according to the invention of claim 5 is a ship that transports natural gas in the form of a slurry and has a strength equal to or higher than a predetermined pressure and is heat-insulated. And a loading and unloading means for loading the slurry-like natural gas into the cargo hold at the loading place and unloading the slurry-like natural gas at the discharge place, and a heat source device capable of cooling the cargo hold to a predetermined temperature. It is characterized by. In order to achieve the above-mentioned object, a natural gas transport ship according to the invention of claim 6 is a ship that transports slurry-like natural gas loaded and pelletized, and has a strength equal to or higher than a predetermined pressure and is heat-insulated. A cargo hold, a cargo handling means for loading the slurry-like natural gas into the cargo hold at the loading place, and a predetermined temperature of the cargo hold during the pelletizing of the slurry-like natural gas loaded in the cargo hold and during the transportation period. A heat source device capable of decomposing the pelletized natural gas by heating it when unloading at the landing site, and a drainage means for discharging only water from the slurry-like natural gas loaded in the cargo hold while cooling the It is characterized by having.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments and examples of the present invention will be described below with reference to the drawings. (First Embodiment) FIGS. 1 to 7 show a first embodiment of the present invention.
It is a figure for explaining the embodiment of. Figure 1
FIG. 1 is a diagram for explaining an entire first transportation system including a natural gas transportation method by a ship of the present invention.

In FIG. 1, the first transportation system 1
a is a gas tank 4a which is a natural gas mining means 3 and a storage facility installed in the loading place 2, a natural gas transport ship 6 equipped with the natural gas pellet manufacturing apparatus 5, and a gas storage tank installed in the landing site 7. 8a and liquid line 9 at loading area 2
a and a gas line 10a at the landing site 7. A natural gas transportation vessel used in such a transportation system will be described with reference to FIGS. 2 to 4.

FIG. 2 is a view showing a natural gas transport ship used in the natural gas transport method by a ship according to the first embodiment of the present invention, and FIG. 2 (1) is a side showing the natural gas transport ship. FIG. 2B is a system diagram showing a heat source device for cooling and heating a plurality of cargo holds of a natural gas transportation ship. Figure 3
It is a top view showing a natural gas transportation ship used for a natural gas transportation method by a ship concerning a 1st embodiment of the present invention. FIG. 4 is a horizontal cross-sectional view showing the natural gas transport ship according to the first embodiment.

In FIG. 2 (1) and FIGS. 3 to 5, the natural gas transport ship 6 is a ship capable of pelletizing and transporting natural gas, and has the following components. That is, as shown in FIG. 2 (1), FIG. 3 and FIG. 4, the natural gas transport ship 6 has a cargo barge 11a, 11a, ... The natural gas pellet manufacturing apparatus 5 that receives natural gas, pelletizes it on the ship, and puts it in the cargo hold 11a, and cools each of the cargo holds 11a, 11a, ... At a predetermined temperature during transportation, and at the landing site 7. When unloading, the heat source device 12 capable of decomposing the heated and pelletized natural gas and the cargo handling means 13 provided in the ship are provided.

That is, the natural gas transport ship 6 shown in FIGS. 3 to 5 has a hull structure having a double bottom 65, a double hull 66 and a central longitudinal bulkhead 67, and an independent tank system provided with a heat insulating material 68. Of the independent cargo tanks 11a, 11a, ...
Are placed regularly on both sides, and each cargo hold 11a, 11
.. have a strength equal to or higher than a predetermined pressure, and the outer circumferences of the cargo holds 11a, 11a ,. By dividing these cargo holds 11a, 11a, ... into starboard and port sides, the respective cargo holds 11a, 11a, ...
It becomes possible to take a large heat exchange area of the refrigerant pipe 20 which is effective for rapid heat exchange with respect to the cargo inside, and also the free surface of the free surface when separated water (water) exists in the cargo hold 11a. It has a structure that can suppress the rise of the center of gravity due to the influence and maintain stability. In addition, these cargo holds 11a, 1
.. are supported by the double bottom 65, the double hull 66, and the central longitudinal bulkhead 67 through the heat insulating material supporting joists 69, and the corner portions of the cargo holds 11a, 11a ,. It has a predetermined curvature to avoid stress concentration due to cooling. In addition, each cargo hold 11a, 11a, ...
A pressure / temperature / liquid level gauge 40 and a safety valve 41 are provided, and are configured so that the environment inside each cargo hold 11a, 11a, ... Can be detected and controlled to a predetermined value.

As shown in FIG. 2B, the heat source device 12 includes a compressor 15, an oil separator 16, a condenser 17, a liquid receiver 18, and an expansion valve used for freezing and heating. 19
, A refrigerant pipe 20, a pipe connecting them, and a valve for determining a pipe path or closing the pipe path. The discharge side of the compressor 15 is connected to the oil separator 16 through a pipe 22 provided with a valve 21. The outlet of the oil separator 16 is branched into a valve 23 and a valve 25 via a pipe 24, and can further communicate with the condenser 17 via the valve 25. The outlet of the condenser 17 can communicate with the liquid receiver 18 through a pipe 27 equipped with a valve 26.
The outlet of the liquid receiver 18 is connected to a pipe 29 equipped with a valve 28.

One end of the refrigerant pipe 20 is connected to the pipe 29 via an electromagnetic valve 30 and an expansion valve 19. One end of the refrigerant pipe 20 is connected to the pipe 33 via the solenoid valve 31.
It is connected to the. The pipe 33 is connected via a valve 34 to a pipe 39 having a valve 35. Piping 24
Is connected to the other end of the refrigerant pipe 20 via an electromagnetic valve 36. One end of the pipe 39 has a compressor 1
5 is connected to the suction port. The refrigerant pipe 20 is shown in FIG.
(2) As shown in FIGS. 3 and 4, each cargo hold 11
are arranged for cooling a, 11a, ...
As shown in FIG. 11, it is stretched around the inner wall of the cargo hold 11a. In addition, inside the cargo hold 11a of the refrigerant pipe 20,
As shown in FIG. 4, a refrigerant pipe protector 38 is provided further inside the refrigerant pipe 20.

Further, each cargo hold 11 of the natural gas transport ship 6
a, 11a, ... As shown in FIG.
The liquid level gauges 40, 40, ... Are provided, and the safety valves 41, 41, ... And the heat insulating hatches 42, 42 ,. In addition, the natural gas transport ship 6 is shown in FIG.
, The engine room 43, the freezer machine room 44,
A pump chamber 47 and the like are provided.

FIG. 5 is a system diagram showing a cargo handling means provided in the natural gas transport ship used in the natural gas transport method by a ship according to the first embodiment of the present invention. As shown in FIG. 5, the cargo handling means 13 provided in the natural gas transport ship 6 has a gas conduit system 45 for guiding the natural gas and a drain pipe system 46 for guiding the water separated from the slurry-like natural gas. Consists of.

Here, the gas conduit system 45 includes a valve 48.
A pipe 49 provided with is connected to the cargo hold 11a, and this pipe 49 is connected to a common pipe 50. This piping 4
Are provided corresponding to the respective cargo holds 11a, 11a ,. A connecting pipe 51 is connected to the common pipe 50, and a valve 52 is provided at the end of the connecting pipe 51. The drainage pipe system 46 includes liquid pumps 55, 55, valves 56, 56 provided on the suction side of the liquid pumps 55, 55, and cargo holds 11a, 11a ,.
57, 57, ... communicating with the respective pipes 57, 57,
, And valves 59, 59 provided on the cargo hold 11a side of each pipe 58.

FIG. 6 is a diagram for explaining the principle of the natural gas pellet manufacturing apparatus used in the natural gas transport ship used in the first embodiment of the present invention. In FIG. 6, the natural gas pellet manufacturing apparatus 5 includes a production container 60,
Stirrer 61, water supply / drainage device 62, and transfer pump 63
And a dehydrator 64, which are configured as follows. Natural gas is supplied to the production container 60. Water is supplied from the water supply / drainage device 62 to the production container 60. The inside of the production container 60 is agitated by an agitator 61. The lower part of the production container 60 is communicated with the suction part of the transfer pump 63. The discharge part of the transfer pump 63 is communicated with the dehydrator 64. The dehydration device 64 is connected to the water supply / drainage device 62.

First, water is put into the production container 60 from the water supply / drainage device 62, and pressurized natural gas is supplied to the production container 60.
The temperature and pressure are set to predetermined values, and if necessary, stirring is performed by the stirrer 61 to generate hydrate (natural gas in the form of slurry). At this time, the slurry hydrate produced in the mixed state of water and hydrate is transferred to the dehydrator 64 by the transfer pump 63. In the dehydrator 64, water is dehydrated from the slurry hydrate to form pellets, and the separated water is sent to the water supply / drainage device 62, and is again returned to the production container 60 by the water supply / drainage device 62.

The term "hydrate" means that natural gas is solidified together with water, and water molecules (under low temperature and high pressure) form hydrogen bonds in the same tetrahedral arrangement as ice. It is an inclusion compound in which gas molecules are incorporated in a cage-like structure made by. Further, the “slurry” is a suspension of a liquid and solid particles, and has a fluidity of 10 to 20,000 [centipoise] obtained by mixing the hydrate and the liquid. The term "pellet" means, among the above-mentioned slurries, those which are mainly made of hydrate only by removing water, and further compressed to increase the density, and to facilitate loading, for example, a cube or a spherical shape. It means the one that is molded into etc. A natural gas transportation method by a ship in such a transportation system will be described based on FIGS. 1 to 6 with reference to FIG.

FIG. 7 is a process diagram showing a natural gas transportation method by a ship according to the first embodiment of the present invention.
(1) illustrates the loading process, FIG. 7 (2) illustrates the transportation process, and FIG. 7 (3) illustrates the unloading process. In FIG. 7, a natural gas transportation method by a ship according to the first embodiment of the present invention is a method of transporting natural gas by a pelletized natural gas transportation ship (ship). According to the conditions shown in 1, the natural gas pelletized by the following steps is transported.

[0023]

[Table 2]

Next, in the first step, in the loading place 2, the gas tank 4a which is a storage facility of the loading place 2 and the natural gas pellet manufacturing apparatus 5 provided on the natural gas transport ship 6 are installed in the gas line 9a. The natural gas is received by the natural gas pellet manufacturing apparatus 5 on the natural gas transport ship 6,
Natural gas is pelletized by the natural gas pellet manufacturing apparatus 5, and the pelletized natural gas is loaded on the cargo hold 11a of the natural gas transport ship 6 which has been cooled to minus 15 [° C] in advance (Fig. 7). (See (1)). The conditions at this time are, as shown in the section of production in the column of Example 1 of Table 2, the state of natural gas is pellets (Pellet),
The temperature is below -15 [℃] and the pressure is 0.02
The pressure is 5 [MPa] or less, and the manufacturing means is a cooling and stirring type, a spray type, or a bubbling type.

Then, in the natural gas transport ship 6, when the cargo ship 11a is filled with the pelletized natural gas, the heat insulating hatch 42 of the cargo ship 11a is closed, and the natural gas pellet manufacturing apparatus 5 is removed from the heat insulating hatch 42. , The natural gas pellet manufacturing apparatus 5 is moved to the position of the next cargo hold 11a, the natural gas pellet manufacturing equipment 5 is connected to the heat shield hatch 42, the heat shield hatch 42 is opened, and the pellets are loaded again on the cargo hold 11a. . By repeating this, when all the cargo holds 11a, 11a, ... Are filled with the natural gas pellets, the preparation for transportation is completed.

Next, in the second step, the cargo hold 11a,
The pellets loaded in 11a, ... Are transported while being cooled at a predetermined temperature under a predetermined pressure (see FIG. 7 (2)). The conditions for this transportation are, as described in the transportation section in the column of Example 1 in Table 2, the state of natural gas is pellets, and the temperature inside the cargo hold 11a is minus 15 [° C].
Below, the pressure in the cargo hold 11a is 0.025 [MPa]
The temperature is kept below, and the cargo hold 11a is cooled and kept warm.

As shown in FIG. 7 and below, the natural gas transport ship 6
The third step starts when the ship arrives at the landing site 7 and berths. In the third step, first, the gas conduit system 45 of the cargo handling means 13 of the natural gas transport ship 6 is connected to the gas line 1 of the landing site 7.
0a to connect the cargo hold 11a of the natural gas transport ship 6 to the storage tank 8a of the landing site 7, close the valves 25 and 37 and the solenoid valve 30 of the heat source device 12, and close the valves 23 and 34, By opening the solenoid valves 31 and 36 respectively, hot gas can be supplied to the refrigerant pipe 20, and the compressor 15 is operated to supply the hot gas to the refrigerant pipe 20 to heat it to decompose the pelletized natural gas. And unloads to storage tank 8.

The conditions of this unloading are, as described in the unloading section of the column of Example 1 in Table 2, the state of natural gas is gaseous, the temperature of the cargo hold 11a is kept at room temperature, and
The means of gasifying and transporting is heating and pumping. The natural gas stored in the storage tank 8a is in a gaseous state as shown in the storage section in the column of Example 1 of Table 2, the storage temperature is room temperature, and the storage means is a pressure tank. is there.

Since the first embodiment is operated as described above, it can be efficiently transported, and if the temperature control is supercooled, the hydrate has a self-preserving effect, so the boil-off amount is reduced. Less is required and transportation efficiency is improved. In addition, although the first embodiment requires a relatively low temperature, the pressure can be kept low, so that the cargo hold 11a can be manufactured relatively easily.

(Second Embodiment) FIG. 8 is a diagram for explaining an entire second transportation system including a natural gas transportation method by a ship according to the present invention. In FIG. 8, the second
Of the transportation system 1b of the natural gas mining means 3 installed in the loading area 2 and a facility 4b for generating and storing the slurry.
And a natural gas transport ship 6 capable of transporting slurry-like natural gas, and a slurry storage tank 8b installed at the landing site 7.
And a liquid line 9b at the loading place 2 and a cargo handling means 10b at the unloading place 7.

Further, in the second embodiment, the natural gas transport ship 6 is different from the first embodiment only in that it is provided with a cargo hold 11b capable of storing slurry-like natural gas. The configuration of is the same as that of the first embodiment. A method of transporting natural gas by a ship using such a second transport system will be described with reference to FIG.

FIG. 9 is a process diagram showing a natural gas transportation method by a ship according to a second embodiment of the present invention.
(1) illustrates the loading process, FIG. 9 (2) illustrates the transportation process, and FIG. 9 (3) illustrates the unloading process. The natural gas transportation method by ship according to the second embodiment of the present invention is a method of transporting natural gas into a slurry (Slurry) by a ship, and according to the conditions shown in Example 2 of Table 3, Slurry by a process like
Transport the shaped natural gas.

First, the conditions of generation, storage and cargo in the cargo land 2 will be described. As shown in Example 2 of Table 3, the state of natural gas is slurry and its temperature is, for example, 1 to 8 [° C]. ] And the pressure is 0.3 [MP
a] or less, and the loading means uses a liquid pump.

In the loading area 2, the natural gas slurried is stored in the facility 4b. In the first step, the facility 4b and the cargo hold 11b of the natural gas transport ship 6 are communicated with each other using the liquid line 9b and the gas conduit system 45 of the cargo handling means 13 and are connected to the liquid pump 70 of the liquid line 9b. And loads the cargo holds 11b, 11b, ... (See FIG. 9 (1)). The conditions at this time are, as shown in the columns of production, storage, and cargo in the column of Example 2 in Table 1, the state of natural gas is slurry, the temperature is kept at, for example, 1 to 8 [° C], and the pressure is kept. Is maintained at 0.3 [MPa] or less, for example. The loading means is the liquid pump 70.

In the natural gas transport ship 6, when the cargo ship 11b is filled with the natural gas in the form of slurry, another cargo ship 1 is carried.
Supply to 1b, and when all the cargo holds 11b are full, move to the next process. In the next second step, the natural gas in the form of a slurry loaded in each of the cargo holds 11b, 11b, ... Is transported while being cooled at a predetermined temperature under a predetermined pressure (see FIG. 9 (2)). The conditions for this transportation are shown in Table 3.
As described in the transportation section in the column of Example 2 of the above, the state of the natural gas is a slurry state, the temperature in the cargo hold 11b is kept at, for example, 1 to 8 [° C.], and the inside of the cargo hold 11b is maintained. Is maintained at, for example, 0.3 [MPa] or less. Further, each cargo hold 11b is cooled and kept warm.

[0036]

[Table 3]

As shown in FIGS. 5 and 8, the third step is started when the natural gas transport ship 6 arrives at the landing site 7 and is at the shore. In the third step, first, the drainage pipe system 46 of the cargo handling means 10b and the gas line 45 communicate with the cargo hold 11b of the natural gas transport ship 6 and the storage tank 8b of the landing site 7, and the pump 55 unloads the cargo. The conditions of this unloading are as described in the unloading section of the column of Example 2 in Table 3,
The state of the natural gas is a slurry state, and the temperature of the cargo hold 11b is maintained at, for example, 1 to 8 [° C] and the pressure of the cargo hold 11b is maintained at, for example, 0.3 [MPa] or less. Further, as a means for carrying, a transfer by a liquid pump 55 is used.

Since the second embodiment is operated as described above, it can be transported efficiently, and if the temperature control is supercooled, the hydrate has a self-preserving effect, so the boil-off amount is reduced. Less is required and transportation efficiency is improved. Further, in the second embodiment, although the pressure is a predetermined value, it can be transported at a relatively high temperature, and the liquid pump can be used for loading and unloading, so that the loading efficiency and the unloading efficiency are improved. Get higher

(Third Embodiment) FIG. 10 is a diagram showing a third transportation system according to a third embodiment of the present invention. In FIG. 10, the third transportation system 1c
Uses the loading method according to the second embodiment (the natural gas mining means 3 of the loading site 2, the facility 4b for slurry generation and storage, and the liquid line 9b) on the loading site 2 side, and transports the natural gas. The natural gas pellets are manufactured in the ship 6 and then transported, and the landing site 7 adopts the unloading method (the storage tank 8a and the gas line 10a of the landing site 7) in the first embodiment.

In short, this third transportation system 1c
Uses the natural gas mining means 3, the facility 4b for slurry generation and storage, and the liquid line 9b on the side of the loading land 2, and uses the gas line 10a and the storage tank 8a on the side of the landing site 7. Further, the feature of the third embodiment is that pellets are produced in the cargo hold 11a of the natural gas transport ship 6. First, generation, storage in the loading area 2,
Explaining the conditions of the cargo, as shown in Example 3 of Table 1, the state of natural gas is a slurry state, the temperature is, for example, 1 to 8 [° C.], and the pressure is, for example, 0.3.
[MPa] or less, and the cargo means uses a liquid pump.

[0041]

[Table 4]

At the loading area 2, the natural gas in the form of slurry is stored in the facility 4b. In the first step, the facility 4b and the cargo hold 11a of the natural gas transport ship 6 are connected using the liquid line 9b and the gas conduit system 45 of the cargo handling means 13 to the liquid pump 70 of the liquid line 9b. And loads the cargo holds 11a, 11a, ... (See FIG. 9 (1)). The conditions at this time are, as shown in the columns of generation, storage, and cargo in the column of Example 3 in Table 4, the state of natural gas is slurry, the temperature is maintained at, for example, 1 to 8 [° C], and the pressure is Is maintained at 0.3 [MPa] or less, for example. When natural gas in a slurry state is filled in the cargo hold 11a in the natural gas transport ship 6, it is supplied to the other cargo hold 11a and all the cargo hold 11a are supplied.
When a is full, move to the next step.

Next, in the first half of the second step, the cargo hold 11
Only water is drained from the slurry-like natural gas in a by the liquid pump 55, and the inside of the cargo hold 11a is cooled by the refrigerant pipe 20 of the heat source device 12. Here, the drainage conditions are, as shown in the drainage section of the column of Example 3 in Table 4, the state of the natural gas is slurry, and the temperature is, for example, 1 to 8.
The temperature is kept at [° C.], for example, 0.3 [MPa] or less, and the water decomposed by heat input from the slurry state is drained by the liquid pump 55.

The conditions after pelletization are as shown in the pellet section in the column of Example 3 in Table 4.
The state of the natural gas is pellets, and the cargo hold 11a is kept at, for example, minus 15 [° C], the cargo hold 11a is kept at 0.025 [MPa] or less, and the cargo hold 11a is cooled and kept warm. deep. By maintaining such conditions, pellets are produced in the cargo hold 11a in the first half of the second step.

Then, in the latter half of the second step, the pelletized natural gas is transported from the loading place 2 to the unloading place 7 by the natural gas transport ship 6 (see FIG. 7 (2)). The conditions for this transportation are, as described in the column of Example 1 of Table 2 and the section of transportation of Example 3 of Table 4, the state of natural gas is pellets, and the temperature in the cargo hold 11a is, for example, The pressure in the cargo hold 11a is maintained at, for example, 0.025 [MPa] or lower at a temperature of -15 [° C] or less, and the cargo hold 11a is cooled and kept warm.

The third step is started when the natural gas transport ship 6 arrives at the landing site 7 and is at the shore. The third step is
First, by connecting the gas conduit system 45 of the cargo handling means 13 of the natural gas transport ship 6 to the gas line 10a of the landing site 7, the cargo hold 11a of the natural gas transport ship 6 is communicated with the storage tank 8 of the landing site 7. The valves 25 and 3 of the heat source device 12
7, the solenoid valve 30 is closed, and the valves 23 and 34 and the solenoid valves 31 and 36 are opened, so that the refrigerant pipe 2
0 is supplied with hot gas, and the compressor 15 is operated to supply the hot gas to the refrigerant pipe 20 to heat it to decompose the pelletized natural gas and unload it to the storage tank 8a.

As described in the unloading section of the column of Example 1 of Table 1, the condition of this unloading is that the state of natural gas is gaseous, the temperature of the cargo hold 11a is kept at room temperature, and
The means for gasifying and transporting is heating and pressure feeding (see FIG. 7 (3)). The conditions for unloading are as described in the unloading column of Example 1 in Table 2 and Example 3 in Table 4.

Since the third embodiment is operated as described above, it can be transported efficiently, and if the temperature control is supercooled, it has a hydrate self-preserving effect, so that the boil-off amount can be reduced. Less is required and transportation efficiency is improved. In addition, in the third embodiment, it is possible to carry at a relatively low pressure during transportation, and at the time of loading, it is possible to carry out loading with a liquid pump and to carry out loading efficiently.

[0049]

As described above, according to the inventions of claims 1 and 4, since the hydrate can be efficiently transported and the hydrate has a self-preserving effect, the storage is relatively low as compared with the liquefied gas. Since the pressure is applied, it is easy to handle, and specifically, there is an effect that the boil-off amount during transportation is small and the safety is improved. In addition, heat input and a certain amount of time are required for hydrate decomposition (gasification), so even if equipment damage occurs during connection work of the transportation line, sudden gas ejection does not occur, Also in that respect, it is extremely safe. Even if the decomposed gas is ignited, the heat of the hydrate surface is removed by the heat of decomposition during decomposition, so the progress of decomposition is suppressed, and therefore the hydrate burns slowly and explodes. There is no fear of this, and there is an effect that extremely safe transportation can be performed. Therefore, transportation efficiency is improved,
Manufacture of cargo holds is relatively easy.

According to the second and fifth aspects of the present invention, in addition to being able to be efficiently transported, if the temperature control is supercooled, the hydrate has a self-preserving effect, so the boil-off amount can be small, Although the transportation efficiency is improved and the liquid can be transported at a relatively high temperature despite having a predetermined pressure, and the liquid pump can be used for loading or unloading, the loading efficiency and the unloading efficiency are increased. According to the third and sixth aspects of the invention, in addition to being able to be efficiently transported, the boil-off amount is small, the transportation efficiency is improved, the transportation can be performed at a relatively low pressure, and the liquid can be transported at the time of loading. It can be loaded with a pump and can be loaded efficiently.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an entire first transportation system including a natural gas transportation method by a ship according to the present invention.

FIG. 2 is a view showing a natural gas transport ship used in the natural gas transport method by a ship according to the first embodiment of the present invention, and FIG. 2 (1) is a side sectional view showing the natural gas transport ship. 2 (2) is a system diagram showing a heat source device for cooling and heating a plurality of cargo holds of a natural gas transport ship.

FIG. 3 is a plan view showing a natural gas transport ship used in the natural gas transport method by a ship according to the first embodiment of the present invention.

FIG. 4 is a horizontal cross-sectional view showing the natural gas transport ship according to the first embodiment of the present invention.

FIG. 5 is a system diagram showing a cargo handling means provided in the natural gas transportation ship used in the natural gas transportation method by the ship according to the first embodiment of the present invention.

FIG. 6 is a diagram for explaining the principle of the natural gas pellet manufacturing apparatus used in the natural gas transport ship used in the first embodiment of the present invention.

FIG. 7 is a process diagram showing a natural gas transportation method by a ship according to the first embodiment of the present invention, wherein FIG. (1) shows a loading process, FIG. (2) shows a transportation process, and FIG. Shows the unloading process respectively.

FIG. 8 is a diagram for explaining the entire second transportation system including the method for transporting natural gas by a ship of the present invention.

9A and 9B are process diagrams showing a natural gas transportation method by a ship according to a second embodiment of the present invention, wherein FIG. 1A is a loading process, FIG. 2B is a transportation process, and FIG. Shows the unloading process respectively.

FIG. 10 is a diagram showing a third transportation system according to a third embodiment of the present invention.

FIG. 11 is a diagram for explaining a conventional natural gas transportation method by a ship, where FIG. (1) shows a state at a loading place, FIG. (2) shows a state during transportation, and FIG. (3) shows an unloading place. The state of each is shown.

[Explanation of symbols]

1a ... the first transportation system, 1b ... second transportation system, 1c ... third transportation system, 2 ... loading area, 3 ... Natural gas mining means, 4a ... a gas tank which is a storage facility, 4b ... Facility (for slurry generation and storage), 5 ... Natural gas pellet manufacturing equipment, 6 ... Natural gas carrier, 7 ... Landing area, 8a, 8b ... storage tank, 9a, 9b ... Liquid line (on the side of the loading place), 10a, 10b ... Gas line (on the unloading side), 11a, 11b ... cargo hold, 12 ... Heat source device, 13 ... cargo handling means, 15 ... compressor, 16 ... Oil separator, 17 ... condenser, 18 ... Receiver, 19 ... Expansion valve, 20 ... Refrigerant tube, 21 ... Valve, 22 ... Piping, 23 ... valve, 24 ... Piping, 25 ... valve, 26 ... Valve, 27 ... Piping, 28 ... Valve, 29 ... Piping, 30 ... Solenoid valve, 31 ... solenoid valve, 33 ... Piping, 34 ... Valve, 35 ... Valve, 36 ... Solenoid valve, 38 ... Refrigerant tube protector, 39 ... Piping, 40 ... Pressure / temperature / level gauge, 41 ... Safety valve, 42 ... Heat shield, 43 ... engine room, 44 ... Refrigerating machine room, 45 ... Gas conduit system, 46 ... drainage system, 47 ... Pump room, 48 ... Valve, 49 ... Piping, 50 ... Common piping, 51 ... Connection piping, 52 ... Valve, 55 ... Liquid pump, 56 ... Valve, 57 ... Piping, 58 ... Valve, 59 ... valve, 60 ... Production container, 61 ... Stirrer, 62 ... Water supply / drainage device, 63 ... Transfer pump, 64 ... dehydrator, 65 ... double bottom, 66 ... Double hull, 67 ... Central longitudinal partition, 68 ... Heat insulating material, 69 ... joists for supporting heat insulating material, 70 ... Liquid pump, 101 ... loading area, 102 ... a storage tank, 103 ... LNG ship, 104 ... cargo tank, 105 ... Liquid line, 106 ... Gas line, 107 ... LNG pump, 108 ... Compressor, 111 ... unloading place, 112 ... a storage tank, 113 ... Liquid line, 114 ... Gas line, 115 ... LNG pump on ship side, 116 ... Compressor,

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tomoji Okui             1-5-20 Kaigan, Minato-ku, Tokyo Tokyo Gas             Within the corporation (72) Inventor Shuhei Suga             945 Shinmachi Ko, Onishi Town, Ochi District, Ehime Prefecture             Shinkurujima Dock Co., Ltd. F-term (reference) 3E072 EA10

Claims (6)

[Claims] 1. A method of pelletizing natural gas and transporting it by ship, the method comprising receiving natural gas at a loading place, pelletizing it on board,
A step of loading the cargo into a cargo hold, a step of transporting the loaded pellets while cooling at a predetermined temperature under a predetermined pressure, and a step of decomposing and unloading the natural gas pelletized by heating at a landing site. A method for transporting natural gas by a ship, which comprises: 2. A method of transporting natural gas in the form of a slurry by a ship, comprising loading the slurry-like natural gas into a cargo hold at a loading place, and loading the loaded slurry-like natural gas under a predetermined pressure. A method for transporting natural gas by ship, comprising: a step of transporting while cooling at a predetermined temperature while transporting; and a step of unloading slurry natural gas at a landing site. 3. A method for loading slurry-like natural gas into a ship and pelletizing and transporting it, comprising the steps of loading the slurry-like natural gas into a cargo hold at a loading point, and the slurry-like natural gas loaded into the cargo hold in the step. Draining the gas from the gas with a drainage pump and cooling the natural gas at a predetermined temperature under a predetermined pressure to pelletize the natural gas; and the natural gas pelletized in the step at a predetermined temperature under a predetermined temperature. A method for transporting natural gas by ship, comprising: a step of transporting while cooling; and a step of decomposing and unloading natural gas pelletized by heating at a landing site. 4. A natural gas transportation ship capable of pelletizing and transporting natural gas, the natural gas pelletizing apparatus for pelletizing the natural gas on a receiving vessel and introducing it into a cargo hold, and a strength higher than a predetermined pressure. Carrying and holding the cargo hold and cooling the cargo hold at a predetermined temperature during transportation,
When unloading at the landing place, natural gas equipped with a heat source device that can decompose the natural gas that has been heated and pelletized, and a cargo handling means that sends the decomposed natural gas to the landing-side facility when unloading. Transport ship. 5. A ship for transporting natural gas in the form of a slurry, the cargo hold having a strength equal to or higher than a predetermined pressure and being insulated, and the natural gas slurry being loaded into the cargo hold at the loading place. A natural gas transport ship, comprising: a cargo handling means capable of unloading slurry-like natural gas at a landing site, and a heat source device capable of cooling the cargo hold to a predetermined temperature. 6. A ship for loading and transporting slurry-like natural gas in the form of pellets, the cargo ship having a strength equal to or higher than a predetermined pressure and being heat-insulated, and the slurry-like natural gas at a loading place. The cargo handling means for loading into the cargo hold, while cooling the cargo hold to a predetermined temperature during pelletization of the slurry natural gas loaded in the cargo hold and during the transportation period, and heating it when unloading at the landing place. A natural gas transport ship comprising a heat source device capable of decomposing pelletized natural gas and a cargo handling means for unloading the decomposed natural gas at a landing site.