Patent Description:
The present application claims priority with respect to <CIT>.

PTL <NUM> discloses using a cargo pump in discharging liquefied gas stored in a tank from the tank in a ship that carries the liquefied gas as a cargo.

In the configuration described in PTL <NUM>, pressure for pumping the liquefied gas is applied to the pump in addition to the pressure of the liquefied gas stored in the tank. Accordingly, the pump is required to have a large pressure capacity in a case where the pressure of the liquefied gas stored in the tank is high.

The liquefied gas in the tank may be discharged by applying pressure to the gas phase in the tank from the outside of the tank. However, in this case, the pressure from the outside is applied to the tank in addition to the pressure of the liquefied gas stored in the tank. Accordingly, the tank itself is required to have a large pressure capacity in a case where the pressure of the liquefied gas stored in the tank is high.

Increasing the pressure capacity of a tank or a pump as described above leads to an increase in cost. Further, an increase in tank size is hindered by the tank itself being required to have a large pressure capacity.

The present disclosure has been made in view of the above, and an object of the present disclosure is to provide a ship in which it is possible to enable an increase in tank size while suppressing an increase in cost.

In order to achieve the above object, a ship according to the present disclosure includes a hull, a main tank, a sub tank, a transportation line, a first line, a second line, a vaporizer, and a pumping unit. The hull has a pair of broadsides. The main tank is provided in the hull. The main tank stores a liquid or gas cargo. The sub tank is smaller in capacity than the main tank and higher in pressure resistance than the main tank. The transportation line is connected to the sub tank. The transportation line has an outboard connection portion. The first line connects the main tank and the sub tank. The second line connects the main tank and the sub tank. The vaporizer is provided on the second line and is not provided on the first line. The vaporizer evaporates a cargo liquid, which is a liquid phase of the cargo, to generate a cargo gas. The pumping unit selects either the first line or the second line to pump the cargo liquid from the main tank to the sub tank. A pressurizing line connects an upper portion in the sub tank and an upper portion in the main tank and pressurizes an inside of the main tank by pressure in the sub tank.

According to the ship of the present disclosure, it is possible to enable an increase in tank size while suppressing an increase in cost.

Hereinafter, a ship according to an embodiment of the present disclosure will be described with reference to <FIG>.

A ship <NUM> of the embodiment of the present disclosure illustrated in <FIG> carries a fluid cargo G such as liquefied carbon dioxide. The ship <NUM> includes at least a hull <NUM>, a main tank <NUM>, a sub tank <NUM>, and a pipe system <NUM> (see <FIG>).

As illustrated in <FIG>, the hull <NUM> has a pair of broadsides 3A and 3B, a ship bottom (not illustrated), and an exposed deck <NUM>, which form the outer shell of the hull <NUM>. The broadsides 3A and 3B are provided with a pair of broadside skins respectively forming the left and right broadsides. The ship bottom (not illustrated) is provided with a ship bottom skin connecting the broadsides 3A and 3B. By the pair of sides 3A and 3B and the ship bottom (not illustrated), the outer shell of the hull <NUM> has a U shape in a cross section orthogonal to a ship stern direction Da. The exposed deck <NUM> is a whole deck exposed to the outside. In the hull <NUM>, an superstructure <NUM> having an accommodation space is formed on the exposed deck <NUM> on a stern 2b side.

In the hull <NUM>, a cargo tank storage compartment (hold) <NUM> is formed closer to a bow 2a side than the superstructure <NUM>. The cargo tank storage compartment <NUM> is recessed toward the ship bottom (not illustrated) below the exposed deck <NUM> and is open upward.

The main tank <NUM> and the sub tank <NUM> are disposed in the cargo tank storage compartment <NUM>. In this embodiment, two main tanks <NUM> as an example are disposed in the cargo tank storage compartment <NUM>. Three sub tanks <NUM> as an example are disposed in the cargo tank storage compartment <NUM>. The main tank <NUM> and the sub tank <NUM> are not limited in any manner in terms of layout and installation number in the cargo tank storage compartment <NUM>.

The sub tank <NUM> is smaller in capacity and higher in pressure resistance than the main tank <NUM>. In other words, the sub tank <NUM> is a small high-pressure tank. On the other hand, the main tank <NUM> is a so-called large low-pressure tank larger in capacity and lower in pressure resistance than the sub tank <NUM>.

In this embodiment, each of the main tank <NUM> and the sub tank <NUM> has, for example, a horizontally extending cylindrical shape. Stored in the main tank <NUM> and the sub tank <NUM> is a liquefied gas to be carried (hereinafter, simply referred to as the cargo G) such as liquefied carbon dioxide. A cargo liquid L, which is the liquid phase of the cargo G, is stored in the lower portions in the main tank <NUM> and the sub tank <NUM>. A cargo gas V, which is the gas phase of the cargo G resulting from the evaporation of the cargo liquid L or the like, is stored in the upper portions in the main tank <NUM> and the sub tank <NUM>. The main tank <NUM> and the sub tank <NUM> are not limited to cylindrical tanks and may be spherical.

As illustrated in <FIG>, the pipe system <NUM> includes a transportation line <NUM>, a first line <NUM>, a second line <NUM>, a vaporizer <NUM>, a pumping unit <NUM>, and a pressurizing line <NUM>.

The transportation line <NUM> is connected to the sub tank <NUM>. The transportation line <NUM> includes an external connection pipe <NUM> and sub tank connection pipes <NUM>.

The external connection pipe <NUM> has an outboard connection portion 31j at one end thereof. The connection portion 31j has a flange or the like, and a delivery pipe (not illustrated) for sending out the cargo G (cargo liquid L) to an outboard liquefied gas storage facility or the like is detachably connected.

The sub tank connection pipes <NUM> are respectively connected to the sub tanks <NUM>. Each sub tank connection pipe <NUM> branches (or merges) from the external connection pipe <NUM> and reaches the inside of the sub tank <NUM>. The lower end of each sub tank connection pipe <NUM> is open to the lower portion in the sub tank <NUM>. Each sub tank connection pipe <NUM> is provided with two opening-closing valves 32v and 32w, which are at an interval in the axis direction of the pipe.

The first line <NUM> connects the main tank <NUM> and the sub tank <NUM> (in this embodiment, the sub tank connection pipe <NUM>). The first line <NUM> includes first main tank connection pipes <NUM>, a first merging pipe <NUM>, and first branch pipes <NUM>.

The first main tank connection pipe <NUM> is provided in each main tank <NUM>. Each first main tank connection pipe <NUM> reaches the inside of the main tank <NUM> from the outside of the main tank <NUM>. The lower end of the first main tank connection pipe <NUM> is open to the lower portion in the main tank <NUM>. Each first main tank connection pipe <NUM> is provided with an opening-closing valve 41v outside the main tank <NUM>.

The plurality of first main tank connection pipes <NUM> connected to the main tanks <NUM> are connected to the first merging pipe <NUM>. As a result, in this embodiment, the two first main tank connection pipes <NUM> extending from the two main tanks <NUM> are connected to one end side of the first merging pipe <NUM>.

The first branch pipe <NUM> is equal in number to the sub tank <NUM>. In this embodiment, three first branch pipes <NUM> are provided. Each first branch pipe <NUM> branches and extends from the other end side of the first merging pipe <NUM>. The first branch pipes <NUM> are connected to the sub tank connection pipes <NUM> extending from the sub tanks <NUM>. Specifically, each first branch pipe <NUM> is connected to the intermediate portion between the opening-closing valve 32v and the opening-closing valve 32w on the sub tank connection pipe <NUM>. Each first branch pipe <NUM> is provided with an opening-closing valve 43v.

The first line <NUM> communicates with the inside of the main tank <NUM> and the inside of the sub tank <NUM> when the opening-closing valves 41v, 43v, and 32v are open. The first branch pipe <NUM> may be directly connected to the sub tank <NUM> without being connected to the sub tank connection pipe <NUM>. In <FIG>, every opening-closing valve is illustrated in white. In <FIG>, the opening-closing valve that is open is illustrated in white and the opening-closing valve that is closed is illustrated in black.

The second line <NUM> connects the main tank <NUM> and the sub tank <NUM>. The second line <NUM> includes second main tank connection pipes <NUM>, a second merging pipe <NUM>, and second branch pipes <NUM>.

The second main tank connection pipes <NUM> are respectively connected to the main tanks <NUM>. Each second main tank connection pipe <NUM> reaches the inside of the main tank <NUM> from the outside of the main tank <NUM>. Each second main tank connection pipe <NUM> is provided with an opening-closing valve 51v outside the main tank <NUM>.

The second main tank connection pipes <NUM> extending from the main tanks <NUM> are connected to the second merging pipe <NUM>. In other words, in this embodiment, two second main tank connection pipes <NUM> extending from two main tanks <NUM> are merged and connected to one end side of one second merging pipe <NUM>.

The second branch pipe <NUM> is equal in number to the sub tank <NUM>. In this embodiment, three second branch pipes <NUM> are provided. Each second branch pipe <NUM> branches and extends from the other end side of the second merging pipe <NUM>. The second branch pipes <NUM> are respectively connected to the sub tanks <NUM>. The lower end of each second branch pipe <NUM> is open to the upper portion in the sub tank <NUM> (for example, uppermost end portion). Each second branch pipe <NUM> is provided with an opening-closing valve 53v.

The vaporizer <NUM> is provided on the second line <NUM> and is not provided on the first line <NUM>. Exemplified in this embodiment is a case where the vaporizer <NUM> is provided on the second merging pipe <NUM> of the second line <NUM>. The vaporizer <NUM> generates the cargo gas V by vaporizing the cargo liquid L flowing in the second line <NUM> (adiabatic expansion). The vaporizer <NUM> evaporates the cargo liquid L by using seawater collected from the outside of the ship, steam generated in the hull <NUM>, or the like as a heat source. Opening-closing valves 52v and 52w are provided in front of and behind the vaporizer <NUM> on the second merging pipe <NUM>.

The second line <NUM> communicates with the inside of the main tank <NUM> and the inside of the sub tank <NUM> when the opening-closing valves 51v, 52v, 52w, and 53v are open.

The pumping unit <NUM> sends out the cargo liquid L stored in the main tank <NUM> to the second main tank connection pipe <NUM>. A pump such as a rotary pump can be used as the pumping unit <NUM>. The pumping unit <NUM> is connected to the second main tank connection pipe <NUM> of the second line <NUM>. More specifically, the pumping unit <NUM> is provided at the lower end of the second main tank connection pipe <NUM> in the main tank <NUM>. The pumping unit <NUM> suctions up the cargo liquid L in the main tank <NUM> and pumps the cargo liquid L.

A connection line <NUM> is provided between the first line <NUM> and the second line <NUM>. The connection line <NUM> connects the first line <NUM> and the second line <NUM>. One end of the connection line <NUM> in this embodiment is connected to the second main tank connection pipe <NUM> between the pumping unit <NUM> and the vaporizer <NUM> on the second line <NUM>. More specifically, one end of the connection line <NUM> is connected to the second main tank connection pipe <NUM> between the opening-closing valve 51v and the opening-closing valve 52v. The other end of the connection line <NUM> is connected to the first main tank connection pipe <NUM> of the first line <NUM>. The other end of the connection line <NUM> is connected to the first main tank connection pipe <NUM> on a side closer to the sub tank <NUM> than the opening-closing valve 41v. The connection line <NUM> is provided with an opening-closing valve 80v, and it is possible to switch between communication and non-communication between the second main tank connection pipe <NUM> and the first main tank connection pipe <NUM> (connectable and disconnectable).

The pressurizing line <NUM> connects the main tank <NUM> and the sub tank <NUM> so as to be capable of communicating with each other. By this pressurizing line <NUM>, the upper portion in the sub tank <NUM> and the upper portion in the main tank <NUM> are capable of communicating with each other. The pressurizing line <NUM> includes sub tank side pressurizing pipes <NUM>, a pressurizing merging pipe <NUM>, and main tank side pressurizing pipes <NUM>.

The sub tank side pressurizing pipe <NUM> is equal in number to the sub tank <NUM>. In other words, in this embodiment, three sub tank side pressurizing pipes <NUM> are provided. Each sub tank side pressurizing pipe <NUM> in this embodiment branches from the second branch pipe <NUM>. More specifically, each sub tank side pressurizing pipe <NUM> is connected to the second branch pipe <NUM> between the sub tank <NUM> and the opening-closing valve 53v. Each sub tank side pressurizing pipe <NUM> is provided with an opening-closing valve 71v. The sub tank side pressurizing pipe <NUM> may be directly connected to the sub tank <NUM> instead of the second branch pipe <NUM>.

Each sub tank side pressurizing pipe <NUM> is connected to the pressurizing merging pipe <NUM>. In other words, in this embodiment, three sub tank side pressurizing pipes <NUM> extending from three sub tanks <NUM> are merged and connected to one end side of one pressurizing merging pipe <NUM>.

The main tank side pressurizing pipe <NUM> is equal in number to the main tank <NUM>. In other words, in this embodiment, two main tank side pressurizing pipes <NUM> are provided. Each main tank side pressurizing pipe <NUM> branches from the other end side of the pressurizing merging pipe <NUM>. The main tank side pressurizing pipes <NUM> are respectively connected to the main tanks <NUM>. The lower end of each main tank side pressurizing pipe <NUM> is open to the upper portion in the sub tank <NUM> (for example, uppermost end portion). Each main tank side pressurizing pipe <NUM> is provided with an opening-closing valve 73v outside the main tank <NUM>.

In the ship <NUM>, by the pipe system <NUM> being provided as described above, two or more (three in this embodiment) sub tanks <NUM> are connected to one main tank <NUM> via the first line <NUM>, the second line <NUM>, and the pressurizing line <NUM>. In addition, two or more (two in this embodiment) main tanks <NUM> are connected to each of the sub tanks <NUM> via the first line <NUM>, the second line <NUM>, and the pressurizing line <NUM>.

As illustrated in <FIG>, when the cargo liquid L in the main tank <NUM> is sent out to the second main tank connection pipe <NUM> by the pumping unit <NUM> with the opening-closing valves 51v and 80v open and the opening-closing valves 41v and 52v closed, the cargo liquid L flows into the first line <NUM> via the second main tank connection pipe <NUM> and the connection line <NUM>. Then, this cargo liquid L is sent to the sub tank <NUM> side as it is through the first line <NUM>.

On the sub tank <NUM> side, on condition that the opening-closing valves 43v and 32v are opened and the opening-closing valve 32w is closed, the cargo liquid L sent through the first line <NUM> can be supplied into the sub tank <NUM>. As a result, the cargo liquid L in the main tank <NUM> can be moved into the sub tank <NUM> with its liquid state maintained.

By closing the opening-closing valve 43v, it is possible to block the cargo liquid L sent through the first line <NUM> from being supplied into the sub tank <NUM>. As a result, it is possible to transfer the cargo liquid L from the main tank <NUM> to a part of the sub tanks <NUM> without transferring the cargo liquid L to the rest.

Although the cargo liquid L is transferred from one main tank <NUM> to two sub tanks <NUM> in the example illustrated in <FIG>, the cargo liquid L may be moved to one sub tank <NUM> or to every sub tank <NUM>.

As illustrated in <FIG>, when the cargo liquid L in the main tank <NUM> is sent out to the second main tank connection pipe <NUM> by the pumping unit <NUM> with the opening-closing valves 51v, 52v, and 52w open and the opening-closing valves 41v and 80v closed, the cargo liquid L is sent to the sub tank <NUM> side through the second line <NUM>. The cargo liquid L is vaporized by the vaporizer <NUM> provided on the second merging pipe <NUM>, and the cargo gas V is generated. The generated cargo gas V is sent to the sub tank <NUM> side through the second line <NUM>.

On the sub tank <NUM> side, on condition that the opening-closing valve 53v is opened, the cargo gas V sent through the first line <NUM> is introduced into the sub tank <NUM>.

The volume of the cargo gas V generated from the cargo liquid L considerably increases as compared with the state where the cargo liquid L is yet to become the cargo gas V. The pressure in the sub tank <NUM> increases when the cargo gas V is introduced into the sub tank <NUM>. As a result, the cargo liquid L is pushed out of the sub tank <NUM> and discharged to the outside of the ship through the transportation line <NUM>.

Here, by closing the opening-closing valve 53v, it is possible to block the cargo gas V sent through the first line <NUM> from being introduced into the sub tank <NUM>. As a result, it is possible to achieve a configuration in which the cargo gas V from the main tank <NUM> is introduced into a part of the sub tanks <NUM> without being transferred to the rest.

Although the cargo gas V is sent into two sub tanks <NUM> from one main tank <NUM> in the example illustrated in <FIG>, the cargo gas V may be discharged from the sub tank <NUM> after the cargo gas V is sent into one sub tank <NUM> or every sub tank <NUM> (that is, three or more sub tanks <NUM>).

After the cargo liquid L in the sub tank <NUM> is discharged as described above, the cargo gas V remains in the sub tank <NUM>. In the sub tank <NUM>, a high-pressure state is maintained by the cargo gas V. With the pressure in the sub tank <NUM> higher than the pressure in the main tank <NUM> as described above, the opening-closing valves 71v and 73v are opened and the opening-closing valves 32v and 52v are closed as illustrated in <FIG>. Then, the upper portion in the sub tank <NUM> and the upper portion in the main tank <NUM> communicate with each other via the pressurizing line <NUM>, and the cargo gas V in the sub tank <NUM> flows into the main tank <NUM>. As a result, the inside of the sub tank <NUM> can be reduced in pressure.

When the cargo gas V in the sub tank <NUM> flows into the main tank <NUM> by the sub tank <NUM> being depressurized as described above, the pressure of the gas phase in the main tank <NUM> (cargo gas V) increases. Then, the pressurized cargo gas V pushes down the cargo liquid L positioned below the cargo gas V in the main tank <NUM>.

At this time, in a case where the cargo gas V is generated by the cargo liquid L pumped by the pumping unit <NUM> being vaporized by the vaporizer <NUM> as in <FIG>, the generated cargo gas V is sent into the sub tank <NUM> that is not in the process of depressurization as illustrated in <FIG>. Then, the cargo liquid L in the sub tank <NUM> into which the cargo gas V is sent is pressurized and the cargo liquid L can be discharged to the outside of the ship.

In this case, by using the pressure of the cargo gas V from the sub tank <NUM> reduced in pressure, the pressure applied to the cargo liquid L by the pumping unit <NUM> is smaller than in a case where the pumping unit <NUM> performs pumping alone.

In addition, as illustrated in <FIG>, the cargo gas V may be sent from the sub tank <NUM> in the process of depressurization into the other main tank <NUM> (main tank <NUM> on the right side in <FIG>) that is not the main tank <NUM> (main tank <NUM> on the left side in <FIG>) in the process of discharge of the sub tank <NUM> by the pumping unit <NUM>. To this end, the opening-closing valves 71v, 73v, 41v, and 43v are opened in the other main tank <NUM>. Then, in the other main tank <NUM>, the pressure of the cargo gas V flowing from the inside of the sub tank <NUM> into the main tank <NUM> pushes down the cargo liquid L positioned below the cargo gas V in the main tank <NUM>. As a result, the cargo liquid L is sent out through the first line <NUM> from the main tank <NUM>. After being sent out, the cargo liquid L is sent into the other sub tank <NUM> (left side in <FIG>) that is not the sub tank <NUM> (sub tank <NUM> at the center in the left-right direction in <FIG>) in the process of depressurization and the sub tank <NUM> (sub tank <NUM> on the right side in <FIG>) in the process of pumping by the pumping unit <NUM>.

The ship <NUM> of the above embodiment includes the hull <NUM>, the main tank <NUM>, the sub tank <NUM>, the transportation line <NUM>, the first line <NUM>, the second line <NUM>, the vaporizer <NUM>, and the pumping unit <NUM>. Further, the sub tank <NUM> is smaller in capacity and higher in pressure resistance than the main tank <NUM>. The first line <NUM> connects the main tank <NUM> and the sub tank <NUM>. The second line <NUM> connects the main tank <NUM> and the sub tank <NUM>. The vaporizer <NUM> is provided on the second line <NUM> and is not provided on the first line <NUM>. The vaporizer <NUM> evaporates the cargo liquid L, which is the liquid phase of the cargo G, to generate the cargo gas V. The pumping unit <NUM> selects either the first line <NUM> or the second line <NUM> and pumps the cargo liquid L from the main tank <NUM> to the sub tank <NUM>.

With this configuration, on condition that the cargo liquid L is pumped from the main tank <NUM> to the sub tank <NUM> through the second line <NUM> by the pumping unit <NUM>, the pumped cargo liquid L is evaporated by the vaporizer <NUM> and the cargo gas V is generated. Then, the pressure in the sub tank <NUM> increases when the cargo gas V generated by the vaporizer <NUM> is sent from the second line <NUM> into the sub tank <NUM>. As a result, the cargo liquid L in the sub tank <NUM> is pushed out and discharged to the outside of the ship through the transportation line <NUM>. Since the cargo liquid L in the sub tank <NUM> is discharged by the pressure of the cargo gas V pumped from the main tank <NUM> side in this manner, the cargo liquid L can be pumplessly discharged from the sub tank <NUM>.

In addition, the sub tank <NUM> is smaller in capacity than the main tank <NUM>. Accordingly, even if the sub tank <NUM> is highly pressure-resistant to the pressure of the cargo gas V, pressure resistance can be easily ensured and low-cost manufacturing can be performed as compared with enhancing the pressure resistance of the large-capacity main tank <NUM> to the same level. On the other hand, since the main tank <NUM> is lower in pressure resistance than the sub tank <NUM>, it is possible to easily realize an increase in the size of the main tank <NUM>. In addition, the pumping unit <NUM> only pumps the cargo liquid L for generating the cargo gas V by vaporization by means of the vaporizer <NUM>. Accordingly, the pumping capacity required for the pumping unit <NUM> is smaller than in a case where the cargo liquid L is directly discharged from the main tank <NUM> to the outside of the ship. As a result, the pumping unit <NUM> can be reduced in cost.

In addition, when the cargo liquid L is pumped from the main tank <NUM> to the sub tank <NUM> through the first line <NUM> by the pumping unit <NUM>, the pumped cargo liquid L is sent into the sub tank <NUM> with its liquid state maintained. As a result, the cargo liquid L stored in the main tank <NUM> can be transferred to the sub tank <NUM>. The cargo liquid L transferred to the sub tank <NUM> is discharged by the pressure of the cargo gas V pumped from the main tank <NUM> side as described above. In other words, it is possible to discharge the entire amount of the cargo liquid L in the main tank <NUM> and the sub tank <NUM> by sequentially repeating the transfer of the cargo liquid L from the main tank <NUM> to the sub tank <NUM> and the discharge of the cargo liquid L from the sub tank <NUM> by the pressure of the cargo gas V pumped from the main tank <NUM> side.

Accordingly, by means of the ship <NUM>, it is possible to enable an increase in tank size while suppressing a rise in cost.

The ship <NUM> of the above embodiment further includes the pressurizing line <NUM> that connects the upper portion in the sub tank <NUM> and the upper portion in the main tank <NUM> and pressurizes the inside of the main tank <NUM> by the pressure in the sub tank <NUM>.

As a result, when the upper portion in the sub tank <NUM> and the upper portion in the main tank <NUM> communicate with each other via the pressurizing line <NUM>, the gas phase in the main tank <NUM> (cargo gas V) is pressurized by the pressure in the sub tank <NUM>. Then, the cargo liquid L positioned in the lower portion in the main tank <NUM> is pressurized by the pressurized cargo gas V, and the cargo liquid L can be transferred from the main tank <NUM> to the sub tank <NUM> through the first line <NUM> and the second line <NUM>. In addition, as a result, it is possible to reduce the pressure of the cargo gas V in the sub tank <NUM>.

In the ship <NUM> of the above embodiment, two or more sub tanks <NUM> are connected to one main tank <NUM> via the first line <NUM>, the second line <NUM>, and the pressurizing line <NUM>.

As a result, it is possible to transfer the cargo liquid L from the main tank <NUM> by the pumping unit <NUM> and send in the cargo gas V through the vaporizer <NUM> with respect to the other sub tank <NUM> while pressurizing the inside of the main tank <NUM> by the pressure of the cargo gas V in the sub tank <NUM> in a part of the sub tanks <NUM>.

In addition, when the cargo liquid L is pumped by the pumping unit <NUM> while pressurizing the main tank <NUM> by the pressure of the cargo gas V in the sub tank <NUM>, the pressure applied to the cargo liquid L by the pumping unit <NUM> can be reduced as compared with a case where the pumping unit <NUM> performs pumping alone. As a result, less energy is required to operate the pumping unit <NUM>.

In the ship <NUM> of the above embodiment, three or more sub tanks <NUM> are provided, and the main tanks <NUM> are connected to each of the sub tanks <NUM> via the first line <NUM>, the second line <NUM>, and the pressurizing line <NUM>. In such a configuration, by pressurizing the main tank <NUM> with the pressure in one of the three or more sub tanks <NUM>, it is possible to generate the cargo gas V while transferring the cargo liquid L to another of the sub tanks <NUM> and discharge the cargo liquid L in the other sub tank <NUM> to the outside of the ship through the transportation line <NUM>.

In this manner, different processes can be performed in parallel in the sub tanks <NUM>. As a result, the cargo liquid L stored in the main tank <NUM> and the sub tank <NUM> can be efficiently discharged to the outside of the ship.

The ship <NUM> of the above embodiment further includes the connection line <NUM> that disconnectably connects the first line <NUM> and the second line <NUM>.

As a result, the cargo liquid L pumped by the pumping unit <NUM> can be sent out with either the first line <NUM> or the second line <NUM> selected.

Although an embodiment of the present disclosure has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment and also includes, for example, design changes within the gist of the present disclosure.

Although two main tanks <NUM> and three sub tanks <NUM> are provided in the above embodiment, the number of the main tanks <NUM> may be two or more and the number of the sub tanks may be three or more. In addition, although it may be impossible to execute the different processes in parallel, the main tank <NUM> and the sub tank <NUM> may be provided one by one.

In addition, the procedure for discharging the cargo liquid L illustrated in the above embodiment is merely an example and can be changed as appropriate.

The ship <NUM> described in the embodiment is, for example, grasped as follows.

An example of the pumping unit <NUM> is a pump.

As for the ship <NUM>, when the cargo liquid L is pumped from the main tank <NUM> to the sub tank <NUM> through the second line <NUM> by the pumping unit <NUM>, the pumped cargo liquid L is evaporated by the vaporizer <NUM> and the cargo gas V is generated. The volume of the cargo gas V generated from the cargo liquid L considerably increases as compared with the state where the cargo liquid L is yet to become the cargo gas V. The pressure in the sub tank <NUM> increases when the cargo gas V is sent into the sub tank <NUM> from the second line <NUM>. As a result, the cargo liquid L in the sub tank <NUM> is pushed out and discharged to the outside of the ship through the transportation line <NUM>.

In this manner, the cargo liquid L in the sub tank <NUM> is discharged by the pressure of the cargo gas V pumped from the main tank <NUM> side, and thus the cargo liquid L can be pumplessly discharged from the sub tank <NUM>. In addition, the sub tank <NUM> is smaller in capacity than the main tank <NUM>. Accordingly, even if the sub tank <NUM> is highly pressure-resistant to the pressure of the cargo gas V, pressure resistance can be easily ensured and low-cost manufacturing can be performed as compared with enhancing the pressure resistance of the large-capacity main tank <NUM> to the same level. On the other hand, since the main tank <NUM> is lower in pressure resistance than the sub tank <NUM>, it is possible to easily realize an increase in the size of the main tank <NUM>. In addition, the pumping unit <NUM> only pumps the cargo liquid L for generating the cargo gas V by vaporization by means of the vaporizer <NUM>. Accordingly, the pumping capacity required for the pumping unit <NUM> is smaller than in a case where the cargo liquid L is directly discharged from the main tank <NUM> to the outside of the ship. As a result, the pumping unit <NUM> can be reduced in cost.

(<NUM>) The ship <NUM> according to a second aspect, which is the ship <NUM> of (<NUM>), further includes a pressurizing line <NUM> connecting an upper portion in the sub tank <NUM> and an upper portion in the main tank <NUM> and pressurizing an inside of the main tank <NUM> by pressure in the sub tank <NUM>.

When the upper portion in the sub tank <NUM> and the upper portion in the main tank <NUM> communicate with each other via the pressurizing line <NUM> in this manner, the inside of the main tank <NUM> is pressurized by the pressure in the sub tank <NUM>. Then, the cargo liquid L positioned in the lower portion in the main tank <NUM> is pressurized by the pressurized cargo gas V, and the cargo liquid L can be transferred from the main tank <NUM> to the sub tank <NUM> through the first line <NUM> and the second line <NUM>. In addition, as a result, it is possible to reduce the pressure of the cargo gas V in the sub tank <NUM>.

(<NUM>) In the ship <NUM> according to a third aspect, which is the ship <NUM> of (<NUM>), a plurality of the sub tanks <NUM> are connected to one main tank <NUM> via the first line <NUM>, the second line <NUM>, and the pressurizing line <NUM>.

As a result, it is possible to transfer the cargo liquid L through the first line <NUM> from the main tank <NUM> by the pumping unit <NUM> and send in the cargo gas V through the second line <NUM> and the vaporizer <NUM> from the main tank <NUM> by the pumping unit <NUM> with respect to the other sub tank <NUM> from the main tank <NUM> while pressurizing the inside of the main tank <NUM> by the pressure of the cargo gas V in the sub tank <NUM> in one or more of the sub tanks <NUM>.

(<NUM>) In the ship <NUM> according to a fourth aspect, which is the ship <NUM> of (<NUM>), the sub tanks <NUM> are three or more in number, and a plurality of the main tanks <NUM> are connected to each of the sub tanks <NUM> via the first line <NUM>, the second line <NUM>, and the pressurizing line <NUM>.

With such a configuration, in three or more sub tanks <NUM>, it is possible to release the residual pressure, transfer the cargo liquid L from the main tank <NUM>, and discharge the cargo liquid L to the outside of the ship in parallel. By sequentially performing these operations between the three or more sub tanks <NUM>, the cargo liquid L stored in the main tank <NUM> and the sub tank <NUM> can be efficiently discharged to the outside of the ship.

(<NUM>) In the ship according to a fifth aspect, which is the ship <NUM> of any one of (<NUM>) to (<NUM>), the pumping unit <NUM> is provided by being connected to the second line <NUM>, and the ship further includes a connection line <NUM> provided to disconnectably connect the first line <NUM> and the second line <NUM> between the pumping unit <NUM> and the vaporizer <NUM>.

Claim 1:
A ship (<NUM>) comprising:
a hull (<NUM>) having a pair of broadsides (3A, 3B);
a main tank (<NUM>) provided in the hull (<NUM>) and storing a liquid or gas cargo (G);
a sub tank (<NUM>) smaller in capacity than the main tank (<NUM>) and higher in pressure resistance than the main tank (<NUM>);
a transportation line (<NUM>) connected to the sub tank (<NUM>) and having an outboard connection portion (31j);
a first line (<NUM>) connecting the main tank (<NUM>) and the sub tank (<NUM>);
a second line (<NUM>) connecting the main tank (<NUM>) and the sub tank (<NUM>);
a vaporizer (<NUM>) provided on the second line (<NUM>), not provided on the first line (<NUM>), and evaporating a cargo liquid (L), which is a liquid phase of the cargo (<NUM>), to generate a cargo gas (V);
a pumping unit (<NUM>) selecting either the first line (<NUM>) or the second line (<NUM>) and pumping the cargo liquid (L) from the main tank (<NUM>) to the sub tank (<NUM>); and comprising a pressurizing line (<NUM>) connecting an upper portion in the sub tank (<NUM>) and an upper portion in the main tank (<NUM>) and pressurizing an inside of the main tank (<NUM>) by pressure in the sub tank (<NUM>).