JP2019034665A - Ship for energy transport - Google Patents

Abstract

To provide an easy-to-use ship for energy transport capable of suppressing the heel amount and of efficiently cooling a cargo tank.SOLUTION: The ship for energy transport includes at least one or more cargo tanks T to store liquefied natural gas and a heel tank used to store the heel, which has less capacity than the cargo tank.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a ship for energy transportation.

  In recent years, the demand for LNG (Liquefied Natural Gas) as a clean energy has increased. Since LNG has a boiling point of around −160 ° C. and an ultra-low temperature, LNG is stored in a special cargo tank that is insulated to keep the temperature below the boiling point during transportation, and is transported while being cooled.

  Most of the LNG stored in the cargo tank is transported as cargo, but a part is used for navigation of LNG transport vessels. For example, a part of LNG vaporized by heat input from the outside of the cargo tank is used as fuel for LNG transportation vessels, and a technique for suppressing and controlling the vaporization of this LNG is disclosed (for example, Patent Document 1). . Some LNG is used for cooling the cargo tank. Hereinafter, LNG used for cooling the cargo tank is referred to as heel.

Japanese Patent Application Laid-Open No. 2014-163412

  The cargo tank needs to be sufficiently cooled not only during transportation of LNG as cargo but also before storing the LNG. That is, for example, even during ballast voyage in which LNG as cargo is not stored, at least one cargo tank can cool all cargo tanks when storing LNG at the next loading site. It is desirable to store an amount of heel. For this reason, in general, not all LNG is fried in the fried land, and a necessary amount of heel is left.

  However, since the cargo tank containing the heel must always be cooled by using this heel, the heel amount further increases in proportion to the number of cargo tanks containing the heel, the cargo tank capacity, and the number of days of voyage. End up. In addition, since cargo tanks have a large volume and surface area and do not have high heat insulation performance suitable for long-term storage of heels, especially for long-term voyages, consider the amount of heel that evaporates in proportion to the number of days. It is necessary to secure. For this reason, there was a problem that the amount of LNG as cargo was pressed.

  The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an energy transportation ship capable of efficiently cooling a cargo tank while suppressing a heel amount.

  According to the present invention, an energy transport ship includes at least one cargo tank that stores liquefied natural gas, and a heel tank that has a smaller volume than the cargo tank and is used to store a heel. .

  ADVANTAGE OF THE INVENTION According to this invention, the ship for energy transportation which can suppress a heel amount and can cool a cargo tank efficiently and is easy to use can be provided.

FIG. 1 is a schematic view illustrating the configuration of an LNG transport ship according to this embodiment. FIG. 2 is a configuration diagram showing an example of the configuration of the cargo area according to the present embodiment. FIG. 3 is a flowchart showing an example of temperature management control of the cargo tank according to the present embodiment. FIG. 4 is a graph illustrating the relationship between the temperature change, pressure change, and gas generation amount of the cargo tank according to this embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same part in subsequent figures, the detailed description is abbreviate | omitted, and a different part is mainly described.

FIG. 1 is a schematic diagram showing a configuration of an LNG transport ship 1 according to the present embodiment.
The LNG transportation ship 1 includes a cargo area 10 including a plurality of tanks T for storing LNG, and a bridge 20.

  In the bridge 20, not only the maneuvering related to the voyage but also the control of the tank T and other command or control of the entire ship are performed. The shape of the bridge and the internal configuration are not limited.

  The tank T includes a cargo tank for storing LNG as a cargo or a tank for storing a heel.

  The bridge 20 includes a control device 22 that controls the temperature, pressure, and the like in each tank T included in the cargo area 10, for example.

  Each tank T in the cargo area 10 is connected by a spray line 12 which is a pipe for transferring LNG. A spray pump for sucking up LNG in each tank T, a spray nozzle for injecting LNG when cooling the tank T, and the like are connected to the tip of the spray line 12. Moreover, in order to prevent vaporization of LNG sucked up by the spray pump, it is preferable that the spray line 12 is excellent in heat insulation performance. Details of the spray pump and the spray nozzle will be described later with reference to FIG.

  Each tank T is provided with a thermometer 30 and a pressure gauge 40. The thermometer 30 measures the member temperature of the inner wall of the tank, the atmospheric temperature in the tank, and the like. The pressure gauge 40 measures the pressure in the tank.

  Each tank T is connected to the control device 22 of the bridge 20 by a control line 14. The control device 22 acquires the temperature value measured by the thermometer 30 of each tank T and the pressure value measured by the pressure gauge 40 via the control line 14. Further, the control device 22 controls the opening and closing of the pump, the cooling device, the piping, and the like through the control line 14 so that the temperature and pressure of each tank T become predetermined values.

  Further, a pipe (vapor line 16) through which gas passes is installed at the top of each tank T. The gas in each tank T flows from the high pressure tank to the low pressure tank through the vapor line 16. Thereby, the pressure in each tank T becomes equal.

FIG. 2 is a configuration diagram illustrating an example of the configuration of the cargo area 10 according to the present embodiment.
The cargo area 10 includes, for example, four cargo tanks T1 to T4 and a heel dedicated tank TH for storing the heel HL.

  Spray nozzles C1 to C4 are installed in the cargo tanks T1 to T4, and these are connected to the spray line 12.

  A spray pump PH and a spray nozzle CH are installed in the heel dedicated tank TH, and these are connected to the spray line 12. Further, the heel dedicated tank TH is connected to the other cargo tanks T1 to T4 via the spray line 12.

  The volume of the heel dedicated tank TH is necessary for replacing the heel amount necessary for cooling the cargo tanks T1 to T4 from room temperature to a low temperature at which cargo can be stored and for replacing the gas in the cargo tanks T1 to T4 with cargo gas. The heel amount is determined based on the heel amount and the heel amount for the number of voyage days required for cooling the heel dedicated tank TH during voyage, and is smaller than the volume of the cargo tanks T1 to T4. That is, the surface area of the inner wall of the heel dedicated tank TH is smaller than the surface area of the inner walls of the cargo tanks T1 to T4. Therefore, the heel amount necessary for cooling the heel dedicated tank TH is smaller than the heel amount necessary for cooling the cargo tanks T1 to T4.

  All heels HL required for cooling the cargo tanks T1 to T4 are stored in the heel dedicated tank TH. Therefore, during the ballast voyage, the cargo tanks T1 to T4 may remain empty (that is, it is not necessary to maintain the cooling state), and the cargo tanks T1 to T4 are kept at room temperature before storing the LNG as the next cargo. To the cargo tank member temperature allowed in terms of tank strength.

  The spray pump PH sucks up the heel HL in the heel dedicated tank TH according to a command from the control device 22 and transfers the sucked up heel HL to the cargo tanks T1 to T4 via the spray line 12.

  The spray nozzles C1 to C4 (or spray nozzle CH) spray the heel sucked up by the spray pump PH according to a command from the control device 22 into each cargo tank T1 to T4 (or heel dedicated tank TH), for example, in a spray form. . The injected heel HL is vaporized in the cargo tanks T1 to T4 (or the heel dedicated tank TH). The cargo tanks T1 to T4 (or the heel dedicated tank TH) are cooled by the heat of vaporization generated when the heel is vaporized.

  As described above, when starting the ballast voyage, the heel HL according to the number of voyage days thereafter so that the cargo tanks T1 to T4 can be cooled and the next LNG can be stored when arriving at the next loading place. Is left in any one or more cargo tanks T1 to T4. Below, the amount of heel required when performing ballast voyage toward the next loading place after filing LNG as cargo in the landing place of LNG is explained.

  First, for example, the amount of heel HL required when storing the heel HL in the cargo tank T1 will be described using a specific example.

  In this case, the cargo tank T1 storing the heel HL needs to be constantly cooled during the ballast voyage. Further, when LNG as cargo is stored after arriving at the landing site, the cargo tanks T2 to T4 need to be further cooled from room temperature to less than the cargo tank member temperature L allowed in terms of LNG tank strength. .

For example, each of the cargo tanks T1 to T4 has a capacity of about 40,000 m ³ , and the heel amount necessary for cooling from room temperature to less than the temperature L per cargo tank is 500 m ³ , maintaining the cooling state per day. It is assumed that the amount of heel necessary for this is 30 m ³ . In this case, for example, when sailing for 30 days, the amount of heel HL required is 2400 m ³ (the amount of heel required for cooling the cargo tanks T2 to T4 from room temperature: 500 m ³ × 3 = 1500 m ³ Heel amount necessary for maintaining the cooling state of the tank T1 for 30 days: a total of 30 m ³ × 30 = 900 m ³ ).

The heel HL may be stored in two or more tanks. For example, when the heel HL is separately stored in the cargo tank T1 and the cargo tank T3, the heel amount necessary is 2800 m ³ (the heel amount necessary for cooling the cargo tanks T2 and T4 from room temperature: 500 m ³ × 2 = 1000 m ³ and the amount of heel required to maintain the cooling state of the cargo tanks T1 and T3 for 30 days: the sum of 30 m ³ × 2 × 30 = 1800 m ³ ). That is, when one tank storing the heel HL increases, the necessary heel amount increases by 400 m ³ .

  Next, the amount of heel HL required when the heel HL is stored in the heel dedicated tank TH will be described.

  In this case, the heel tank TH needs to be constantly cooled during the ballast voyage. Furthermore, when LNG as cargo is stored after arriving at the landing site, the cargo tanks T1 to T4 need to be further cooled from room temperature to below the cargo tank member temperature L allowed in terms of LNG tank strength. .

For example, the heel dedicated tank TH has a capacity of about one-tenth (4000 m ³ ) of the cargo tanks T1 to T4, and the heel amount required for cooling from room temperature to less than the temperature L per heel dedicated tank is 50 m ³ . Yes, it is assumed that the heel amount necessary to maintain the cooling state per day is 4 m ³ . In this case, for example, when sailing on the 30th, the necessary heel HL amount is 2120 m ³ (the heel amount necessary for cooling the cargo tanks T1 to T4 from room temperature: 500 m ³ × 4 = 2000 m ³ , The amount of heel required for maintaining the cooling state of the dedicated tank TH for 30 days: a total of 4 m ³ × 30 = 120 m ³ ).

The cargo area 10 may be provided with two or more heel tanks TH. In this case, on the 30th voyage, the heel amount necessary for one heel dedicated tank TH increases by 120 m ³ .

  Therefore, the amount of heel HL required when storing the heel HL in the heel dedicated tank TH is smaller than the amount of heel HL required when storing the heel HL in any of the cargo tanks T1 to T4. . Further, when the heel HL is stored separately in two or more cargo tanks, the amount of increase in the heel HL required for the heel HL required when storing the heel HL in two or more heel dedicated tanks TH is as follows. Much less than the increase.

  Furthermore, since the volume of the heel dedicated tank TH is smaller than the cargo tanks T1 to T4, the heel amount necessary to maintain the cooling state of the heel dedicated tank TH is necessary to maintain the cooling state of the cargo tanks T1 to T4. The amount of heel is small. For this reason, the effect of reducing the heel amount by providing the heel dedicated tank TH increases in proportion to the number of sailing days.

  In the present embodiment, the heel dedicated tank TH is preferably installed near the center of the positions of the other cargo tanks T1 to T4. Thereby, the distance from heel exclusive tank TH to each cargo tank T1-T4 becomes short, and the heel HL can be transferred efficiently.

  Moreover, it is preferable that the heel exclusive tank TH is excellent in heat insulation performance compared with the cargo tanks T1-T4. As a result, the cooling efficiency of the heel dedicated tank TH is improved, so that the amount of the heel HL can be further reduced.

  FIG. 3 is a flowchart showing an example of temperature management control of the cargo tanks T1 to T4 according to the present embodiment. More specifically, FIG. 3 shows an example of processing when the control device 22 performs temperature management control on the cargo tanks T1 to T4 during the ballast voyage.

  In step S101, the control device 22 determines whether or not the loading area is approaching. When it is determined that the loading area is not approaching, the control device 22 does nothing with the cargo tanks T1 to T4. In addition, when temperature management control is not performed, the temperature of the cargo tanks T1 to T4 is raised (hot up) to room temperature or outside temperature.

  On the other hand, when it is determined in step S101 that the loading area is approaching, the control device 22 performs temperature management control of all the cargo tanks T1 to T4 in step S102. The temperature management control is, for example, control for cooling the cargo tanks T1 to T4 to a predetermined temperature at which the LNG can be stored.

  Note that the control device 22 may determine whether or not the loading area is approaching based on, for example, whether or not the remaining voyage days to the loading area is equal to or less than a predetermined number of days, or the distance to the loading area. You may judge by whether or not is below a predetermined distance.

  Here, the example of the temperature management control performed with respect to the cargo tank T1 among the cargo tanks T1-T4 is shown below. In addition, the control apparatus 22 performs the same temperature management control also about other cargo tanks T2-T4.

  First, the control device 22 sucks a predetermined amount of heel out of the heel HL by the spray pump PH, and starts injection from the spray nozzle C1. Since the volume increases when the heel vaporizes and becomes gaseous, the pressure in the cargo tanks T1 to T4 and the heel dedicated tank TH (each tank T) increases as the heel is injected.

  Therefore, the control device 22 stops the heel injection when the pressure in each tank T becomes larger than a predetermined upper limit value, for example, and lowers the pressure in each tank T by removing the vaporized gas in each tank T. The vaporized heel is used, for example, as fuel for the LNG transport ship 1.

  When the control device 22 interrupts the heel injection, the temperature in the cargo tank T1 rises again due to heat input from the outside. Therefore, when the temperature in the cargo tank T1 becomes higher than a predetermined upper limit value, for example, the control device 22 starts heel injection from the spray nozzle C1 again, and lowers the temperature in the cargo tank T1.

  The control device 22 keeps the temperature in the cargo tank T1 in a cooled state by controlling the pressure and temperature by repeatedly injecting the heel and degassing the cargo tank T1 in this way.

  In addition, when cooling two or more cargo tanks, the control device 22 preferably performs heel injection by shifting the timing of control for a predetermined time between the cargo tanks so that heel injection does not occur simultaneously. Thereby, it is avoided that the heel is vaporized in a plurality of cargo tanks and a large amount of gas is generated.

  Further, it is preferable that all the cargo tanks T1 to T4 are cooled to the target temperature and the temperature is constant at the time of arrival at the loading site (immediately before loading LNG as the next cargo). Therefore, in addition to the cooling in step S103 performed for each of the cargo tanks T1 to T4, the control device 22 manages the temperature of the cargo tanks T1 to T4 so that the temperature of the entire cargo tanks T1 to T4 is constant and approaches the target temperature. May be. More specifically, for example, the control device 22 checks the temperature of all the remaining cargo tanks every time a heel injection is completed for one cargo tank, and determines the number of heel injections of the cargo tank that needs to be cooled. May increase. Further, at a certain point in time when the control device 22 stops the temperature management control, the temperature of the cargo tank that has finished the heel injection first becomes higher than the temperature of the cargo tank that has finally finished the heel injection. For this reason, the control apparatus 22 may change the target temperature of a cargo tank according to the order which finishes injection of a heel.

  In the present embodiment, the control device 22 activates the spray pump PH of the heel dedicated tank TH when, for example, the pressure in the tank to be cooled is lower than a predetermined lower limit value, and from the spray nozzle of the tank. When the heel is injected and the pressure in the tank rises above a predetermined upper limit value, the spray pump PH may be stopped to stop the heel injection.

  Further, for example, when the temperature in the tank to be cooled rises above a predetermined upper limit value, the control device 22 activates the spray pump PH of the heel dedicated tank TH, and injects the heel from the spray nozzle of the tank, When the temperature in the tank falls below a predetermined lower limit value, the spray pump PH may be stopped and heel injection may be stopped.

  Further, the control device 22 combines some of the upper limit value or the lower limit value of the temperature, the upper limit value or the lower limit value of the pressure, the upper limit value or the lower limit value of the gas amount generated by the injection of the heel as a control factor, and You may control injection and stop of injection.

  In the present embodiment, the heel dedicated tank TH is constantly cooled by the control device 22 in order to store the heel. As with the cargo tanks T1 to T4, the heel dedicated tank TH is cooled by the control device 22 sucking up the heel HL using the spray pump PH and ejecting the sucked heel HL from the spray nozzle CH.

  FIG. 4 is a graph illustrating the relationship between the temperature change, pressure change, and gas generation amount of the cargo tanks T1 to T4.

  More specifically, FIG. 4 shows the change in pressure (G1), temperature (G2), and gas generation per unit time in one of the cargo tanks T1 to T4. (G3) is shown. The horizontal axis of the graph represents the time from the landing site arrival to the loading site arrival, and the vertical axis represents the cargo tank pressure, temperature, and gas generation amount.

  The control device 22 controls the temperature of the cargo tank so that the pressure in the cargo tank does not exceed the upper limit value (V1) of the pressure and the upper limit value (V2) of the gas generation amount. Temperature management control is performed so as to be within V4).

  For example, the control device 22 activates the spray pump at time points B1 to B4 to start cooling the cargo tank T1 (heel injection), and stops cooling the cargo tank T1 (heel injection) at the time points E1 to E4. . The control device 22 performs the cooling control in the same manner in all the other cargo tanks T2 to T4.

  In addition, the control device 22 controls the temperature so that all the cargo tanks T1 to T4 are cooled to the target temperature and the temperature is constant before arrival at the loading site (immediately before loading the LNG as the next cargo). Take control.

  According to the present embodiment described above, the LNG transportation ship 1 is provided with the small heel dedicated tank TH having excellent heat insulation performance. Thereby, compared with the case where a heel is stored in either of cargo tanks T1-T4, the tank which stored the heel can be cooled with a very small heel amount. Therefore, even when the number of voyage days increases, an increase in the necessary heel amount can be suppressed.

  In addition, when the heel tank TH is not provided, when the cargo tanks T1 to T4 are hot-up during voyage, the cargo tanks T1 to T4 are cooled while arriving at the facility holding the LNG for a long time and receiving the LNG supply. Need to do work. On the other hand, according to the LNG transportation ship 1 according to this embodiment, even when the cargo tanks T1 to T4 are hot-up during voyage, the LNG is loaded into the heel dedicated tank TH from the hot-up state of the cargo tanks T1 to T4. By storing a certain amount of heel necessary for cooling to a possible temperature, the cargo tanks T1 to T4 can be cooled without occupying a facility that holds LNG.

  In addition to the cargo tanks T1 to T4, even when the heel dedicated tank TH is hot up, the heel dedicated tank TH having a smaller volume than the cargo tanks T1 to T4 is cooled and the heel is mounted. Can be used to cool the cargo tanks T1 to T4 during the voyage. For this reason, the period which occupies the facility which holds LNG for the cooling operation | work of the cargo tanks T1-T4 can be shortened.

  In this embodiment, when the heel is stored in any of the cargo tanks T1 to T4, the control device 22 approaches the cargo tank storing the heel that needs to be constantly cooled before reaching the loading site. Then, it is necessary to perform temperature management considering both states of the cargo tank that does not store the heel that starts cooling. Therefore, the temperature averaging control in this case is more complicated than the temperature averaging control in the case where the heel dedicated tank TH is provided and the heel is stored only in the heel dedicated tank TH. That is, by providing the heel dedicated tank TH, the control device 22 can separately control the cooling of the heel and the cooling of the cargo tank, so that the temperature control becomes easy.

  In addition, when the cargo tanks T1 to T4 are filled with an inert gas that is not LNG gas (hereinafter referred to as cargo gas) (gas-free state), the cargo tank T1 is temporarily stored before storing the LNG. It is necessary to replace the inert gas of ~ T4 with cargo gas. At this time, if the heel dedicated tank TH is not provided, it is necessary to berth for a long time at the facility that holds the LNG and perform the gas replacement work while receiving the supply of the LNG. On the other hand, according to the LNG transport ship 1 according to the present embodiment, for example, without occupying a facility that holds LNG, the heel of the tank for exclusive use of heel TH is used during the voyage to generate the inert gas in the cargo tanks T1 to T4. It becomes possible to perform the operation of replacing with LNG gas.

  Further, even when the heel dedicated tank TH is in a gas-free state in addition to the cargo tanks T1 to T4, the inert gas in the heel dedicated tank TH having a smaller volume than the cargo tanks T1 to T4 is replaced with the cargo gas, and the heel The dedicated tank TH may be cooled and loaded with LNG. Therefore, as compared with the case where there is no heel dedicated tank TH, the gas replacement work can be completed by the ship alone without being limited to the place where the LNG is loaded, and further, the period of occupying the facility holding the LNG is shortened. can do.

  In the present embodiment, the control device 22 may calculate in advance the total amount of gas generated by injecting the heel, and set a voyage plan based on the calculation result. The voyage plan is generally set in consideration of, for example, the speed of the ship determined based on the time and distance from the landing landing arrival time to the loading arrival time, and the geographical and weather requirements. Based on this voyage plan, the amount of gas required by the propulsion engine of the LNG transport ship 1 is determined. The control device 22 sets a voyage plan by comparing the total amount of gas generated with the amount of gas required by the propulsion engine. When the amount of gas is insufficient, the control device 22 makes a voyage plan to use a fuel other than gas (for example, heavy oil), for example, and when the amount of gas is excessive, for example, cooling timing of the cargo tank, cooling A voyage plan may be made to appropriately adjust temperature, route, ship speed, and the like.

  Note that the present invention is not limited to the above-described embodiments, and each embodiment can be carried out by deleting, adding, or changing components. Moreover, it can implement in a further different form by combining or exchanging each component of each embodiment suitably. As described above, even if the embodiment is directly different from the above-described embodiment, the same object as the present invention is described as the embodiment of the present invention, and the description thereof is omitted. Yes.

DESCRIPTION OF SYMBOLS 1 ... Ship for LNG transportation, 10 ... Cargo area, 12 ... Spray line, 14 ... Control line, 16 ... Vapor line, 20 ... Bridge, 22 ... Control device, 30 ... Thermometer, 40 ... Pressure gauge, T ... Tank

Claims (3)

At least one cargo tank for storing liquefied natural gas;
A ship for energy transportation comprising a heel tank having a smaller volume than the cargo tank and used for storing a heel. A pump for sucking up the heel from the heel tank;
A nozzle for injecting the heel into the heel tank and the cargo tank;
Further comprising
The ship for energy transportation according to claim 1, wherein said pump and said nozzle are connected by piping excellent in heat insulation performance. A thermometer for measuring the temperature of members and / or atmosphere in the cargo tank;
A pressure gauge for measuring the pressure in the cargo tank;
Based on the temperature measured by the thermometer or the pressure measured by the pressure gauge, the start and stop of the injection of the heel sucked up from the heel tank is controlled and / or transferred to the propulsion engine as fuel. Control means for controlling the temperature or the pressure in the cargo tank by controlling the amount of gas to be produced;
The ship for energy transportation according to claim 2, further comprising:

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