Storage tank for liquefied fuel

Abstract

A storage tank 10A has a heat insulating material layer 14 formed on the outer side of a partition wall 12 that has a container shape. The inside of the storage tank 10A is divided into two storage spaces V.sub.1, V.sub.2. The first storage space V.sub.1 stores liquefied hydrogen LH.sub.2 and the second storage space V.sub.2 storing slush hydrogen SH.sub.2. A plurality of fins 18 are disposed on the partition plate 16 so as to promote heat transfer between the liquefied hydrogen LH.sub.2 and the slush hydrogen SH.sub.2 and to reduce the amount of evaporation gas from the liquefied hydrogen LH.sub.2. An escape pipe 20 is connected to the storage space V.sub.1, and the fuel supply pipes 24a, 24b are connected to the storage spaces V.sub.1, V.sub.2, respectively. The fuel supply pipes 24a, 24b are connected to a combustor 26 via the main fuel pipe 24.

Claims

1. A liquefied-fuel storage tank, comprising: a partition wall of a container shape forming a storage space inside; a heat insulating material layer formed on the partition wall; a partition plate dividing the storage space into a first storage space and a second storage space, the first storage space storing liquefied fuel and the second storage space storing slush fuel which has a lower temperature than the liquefied fuel and which includes a mixture of a solid phase fuel and a liquid phase fuel; a heat transfer unit disposed on the partition plate, the heat transfer unit being configured to promote heat transfer between the liquefied fuel and the slush fuel; an outlet for discharging evaporation gas in the first storage space when a pressure of the first storage space reaches a setting pressure; and a fuel supply system for supplying the liquefied fuel from the first storage space and the liquid phase fuel from the second storage space to a combustor, wherein the partition plate is configured to shut off a flow of the liquefied fuel from the first storage space to the second storage space, and wherein the partition plate is further configured to shut off a flow of the slush fuel from the second storage space to the first storage space.

2. The liquefied-fuel storage tank according to claim 1, wherein the heat transfer unit includes a plurality of fins mounted to the partition plate so as to protrude into the first storage space and the second storage space.

3. The liquefied-fuel storage tank according to claim 1, wherein the heat transfer promoting unit includes a heat pipe mounted to the partition plate, the heat pipe including a working-fluid heating part disposed in the first storage space and a working-fluid cooling part disposed in the second storage space.

4. The liquefied-fuel storage tank according to claim 1, wherein a container which is formed by the partition plate and forms the second storage space is disposed in the storage space so that an entire periphery of the container is surrounded by the first storage space, and wherein the heat transfer unit is disposed on the partition plate which forms the container.

5. A liquefied-fuel storage tank, comprising: a partition wall of a container shape forming a storage space inside; a heat insulating material layer formed on the partition wall; a partition plate dividing the storage space into a first storage space and a second storage space, the first storage space storing liquefied fuel and the second storage space storing slush fuel which has a lower temperature than the liquefied fuel and which includes a mixture of a solid phase fuel and a liquid phase fuel; a heat transfer unit disposed on the partition plate, the heat transfer unit being configured to promote heat transfer between the liquefied fuel and the slush fuel; an outlet for discharging evaporation gas in the first storage space when a pressure of the first storage space reaches a setting pressure; and a fuel supply system for supplying the liquefied fuel from the first storage space and the liquid phase fuel from the second storage space to a combustor, wherein a container which is formed by the partition plate and forms the second storage space is disposed in the storage space so that an entire periphery of the container is surrounded by the first storage space, and wherein the heat transfer unit is disposed on the partition plate which forms the container.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a front cross-sectional view of a storage tank according to the first embodiment of the first aspect of the present invention.

(2) FIG. 2 is a front cross-sectional view of a storage tank according to the second embodiment of the first aspect of the present invention.

(3) FIG. 3 is a front cross-sectional view of a storage tank according to the third embodiment of the first aspect of the present invention.

(4) FIG. 4 is a front cross-sectional view of a storage tank according to the fourth embodiment of the first aspect of the present invention.

(5) FIG. 5 is a front cross-sectional view of a storage tank according to the fifth embodiment of the first aspect of the present invention.

(6) FIG. 6 is a front cross-sectional view of a storage tank according to the first embodiment of the second aspect of the present invention.

(7) FIG. 7 is a partial enlarged cross-sectional view of the storage tank in FIG. 6.

(8) FIG. 8 is a front cross-sectional view of a storage tank according to the second embodiment of the second aspect of the present invention.

(9) FIG. 9 is a partial enlarged cross-sectional view of the storage tank in FIG. 8.

(10) FIG. 10 is a front cross-sectional view of a storage tank according to the third embodiment of the second aspect of the present invention.

(11) FIG. 11 is a front cross-sectional view of a storage tank according to the fourth embodiment of the second aspect of the present invention.

DETAILED DESCRIPTION

(12) Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It is intended, however, that unless particularly specified, dimensions, materials, shapes, relative positions and the like of components described in the embodiments shall be interpreted as illustrative only and not limitative of the scope of the present invention.

Embodiment 1

(13) Now, the first embodiment of the first aspect of the present invention will be described with reference to FIG. 1. The first embodiment is applied to a storage tank for storing liquefied hydrogen. The storage tank 10A of the present embodiment is mounted to a rocket for launching a satellite or the like. The storage tank 10 includes a partition wall 12 of a container shape. A heat insulating material layer 14 is formed on the outer surface of the partition wall 12. The heat insulating material layer 14 includes, for instance, a heat insulating material such as a radiation heat insulating material and a foaming heat insulating material obtained by foam molding of rigid urethane or polystyrene. The inside of the storage tank 10A is partitioned by a partition plate 16 that has a flat shape and is made from steel, so as to be divided in half.

(14) Liquefied hydrogen LH.sub.2 is stored in a storage space V.sub.1 formed at one side of the partition plate 18, while slush hydrogen (hydrogen including liquefied hydrogen and solidified hydrogen mixed like sherbet) SH.sub.2 is stored in a storage space V.sub.2 formed on the other side of the partition plate 16. The liquefied hydrogen LH.sub.2 has a temperature of 20K, while the slush hydrogen SH.sub.2 has a temperature of 13K. A plurality of fins 18 is mounted over the entire region of the partition plate 16. The fins 18 are spaced from one another and arranged in a direction such that the fins 18 protrude into the storage spaces V.sub.1 and V.sub.2.

(15) An escape pipe 20 communicating with the storage space V.sub.1 is connected to the partition wall 12 forming the storage space V.sub.1. The escape pipe 20 includes a safety valve 22 for opening the escape pipe 20 when the pressure of the storage space V.sub.1 reaches a setting pressure. The side surface 12a of the partition wall 12 of the storage tank 10 is directly exposed to the outer space. Thus, the side wall 12a of the partition wall 12 is mainly exposed to sunlight and reflection light from the earth, which results in inward penetration of radiation heat h. Fuel supply pipes 24a and 24b are connected to the storage spaces V.sub.1 and V.sub.2, respectively, and to a combustor 26 of the rocket via a main fuel pipe 24.

(16) In the above configuration, the slush hydrogen SH.sub.2, which has a lower temperature than the liquefied hydrogen LH.sub.2, exchanges heat with the liquefied hydrogen LH.sub.2 via the fins 18, thereby cooling the liquefied hydrogen LH.sub.2. Thus, heat having penetrated into the storage space V.sub.1 transfers to the slush hydrogen SH.sub.2 via the liquefied hydrogen LH.sub.2, so as to be used as latent heat of fusion of the slush hydrogen SH.sub.2. In this way, it is possible to reduce an amount of evaporation gas from the liquefied hydrogen LH.sub.2. The slush hydrogen SH.sub.2 having melted in the storage space V.sub.2 is supplied to the combustor 26, and can be used as fuel. Here, if the amount of evaporation of the liquefied hydrogen LH.sub.2 in the storage space V.sub.1 increases and the pressure of the storage space V.sub.1 rises to a setting pressure, the safety valve 22 opens to discharge the evaporation gas, which makes it possible to decrease the pressure of the storage space V.sub.1 to the setting pressure or less.

(17) According to the present embodiment, heat transfer between the liquefied hydrogen LH.sub.2 and the slush hydrogen SH.sub.2 is promoted by the fins 18, which makes it possible to reduce the amount of evaporation gas from the liquefied hydrogen LH.sub.2. Further, flow between the storage space V.sub.1 and the storage space V.sub.2 is shut off by the partition plate 16, which prevents natural convection that prevails in the entire storage space. As a result, the amount of heat transferring to the liquefied hydrogen LH.sub.2 is restricted, which makes it possible to reduce the amount of evaporation gas in the storage space V.sub.1. As described above, the cold of the slush hydrogen SH.sub.2 is utilized, which makes it possible to reduce the amount of evaporation gas from the liquefied hydrogen LH.sub.2 without requiring an additional refrigerating device or the like. Moreover, since the fins 18 are provided to transfer heat between the liquefied hydrogen LH.sub.2 and the slush hydrogen SH.sub.2, it is possible to transfer heat easily and at low cost.

Embodiment 2

(18) Next, the second embodiment of the first aspect of the present invention will be described with reference to FIG. 2. A storage tank V10B is mounted to a rocket, similarly to the above storage tank 10A. The storage tank 10B employs a heat pipe 30 as a heat transfer unit. The heat pipe 30 includes a hollow pipe through which working fluid flows. As working fluid, for instance, high-carbon ammonia solution is used. A heating part 32 for absorbing heat from the liquefied hydrogen LH.sub.2 is disposed in the storage space V.sub.1, while a cooling part 34 for discharging heat to the slush hydrogen SH.sub.2 is disposed in the storage space V.sub.2. Each of the heating part 32 and the cooling part 34 includes a plurality of fins 36 for promoting heat transfer. Other configuration is identical to that of the first embodiment, and a common component is associated with a common reference sign, in accordance with the above description.

(19) The working fluid in the heat pipe 30 absorbs heat from the liquefied hydrogen LH.sub.2 and evaporates at the heating part 32. The vaporized working fluid shifts to the cooling part 34, and heats the slush hydrogen SH.sub.2 and condenses at the cooling part 34. The condensed working fluid shifts to the heating part 32. According to the present embodiment, providing the heat pipe 30 promotes heat transfer between the liquefied hydrogen LH.sub.2 and the slush hydrogen SH.sub.2, which makes it possible to enhance the cooling effect for the liquefied hydrogen LH.sub.2 (see Japanese Patent No. 3416731 for details of the heat pipe 30).

Embodiment 3

(20) Next, the third embodiment of the first aspect of the present invention will be described with reference to FIG. 3. The present embodiment is different from the second embodiment in that a storage tank 10C includes two or more heat pipes 30A, 30B. Each of the heat pipes 30A, 30B has the same configuration as that of the heat pipe 30 in the second embodiment. That is, heating parts 32a, 32b are disposed in the storage space V.sub.1 and cooling parts 34a, 34b are disposed in the storage space V.sub.2. The heat pipes 30A, 30B are disposed at the vicinity of the inner side of the side wall 12a. While FIG. 3 illustrates two heat pipes 30A, 30B, three or more heat pipes may be arranged in the circumferential direction. Other configuration is identical to that of the first embodiment.

(21) According to the present embodiment, the plurality of heat pipes 30A, 30B is disposed in the vicinity of the inner side of the side wall 12a, through which a large amount of heat penetrates. In this way, it is possible to increase the amount of heat absorption by the heat pipes 30A, 30B with respect to the amount of heat penetration. Thus, it is possible to reduce the amount of evaporation gas from the liquefied hydrogen LH.sub.2.

Embodiment 4

(22) Next, the fourth embodiment of the first aspect of the present invention will be described with reference to FIG. 4. A storage tank 10D of the present embodiment includes a container 40 of a sealed shape disposed in the storage space V.sub.1 filled with the liquefied hydrogen LH.sub.2. The inside of the container 40 forms the storage space V.sub.2 filled with the slush hydrogen SH.sub.2 The partition wall 42 of the container 40 includes a plurality of fins 44 for promoting heat transfer between the liquefied hydrogen LH.sub.2 and the slush hydrogen SH.sub.2, arranged at certain intervals over the entire surface of the partition wall 42. The fuel supply pipe 24b is connected to the container 40, and to the main fuel pipe 24 through the storage space V.sub.1. Other configuration is identical to that of the first embodiment.

(23) According to the present embodiment, the amount of heat absorbed by the slush hydrogen SH.sub.2 is to be entirely absorbed from the liquefied hydrogen LH.sub.2, which makes it possible to enhance the cooling effect for the liquefied hydrogen LH.sub.2. Thus, it is possible to reduce the amount of evaporation gas from the liquefied hydrogen LH.sub.2. Further, it is possible to ensure a wide space for disposing the fins 44, which makes it possible to improve the flexibility of layout for the fins 44, and to increase the amount of heat transfer by providing a number of fins 44.

Embodiment 5

(24) Next, the fifth embodiment of the first aspect of the present invention will be described with reference to FIG. 5. A storage tank 10E according to the present embodiment is different from the storage tank 10D in the fourth embodiment in that it includes a plurality of heat pipes 46 as a heat transfer unit, instead of the fins 44. That is, a plurality of heat pipes 46 is disposed on the partition wall 42 of the tank 40, with the heating parts of the heat pipes 46 disposed in the storage space V.sub.1 and the cooling parts of the heat pipes 46 disposed in the storage space V.sub.2. Other configuration is identical to that of the fourth embodiment.

(25) According to the present embodiment, it is possible to ensure a wide space for disposing the plurality of heat pipes 46, and thus to improve the flexibility of layout of the heat pipes 46. Further, providing the plurality of heat pipes 46 enhances the cooling effect for the liquefied hydrogen LH.sub.2, which makes it possible to reduce the amount of evaporation gas from the liquefied hydrogen LH.sub.2.

Embodiment 6

(26) Next, the first embodiment of the second aspect of the present invention will be described with reference to FIGS. 6 and 7. With reference to FIG. 6, a storage tank 10F of the present embodiment is to be mounted to a rocket for launching a satellite or the like. The partition wall 50 of the storage tank 10F includes a double wall including an inner wall 52 and an outer wall 54. Further, a filling space s is formed between the inner wall 52 and the outer wall 54, and filled with carbon nanotubes 56. A pipe 58 is connected to the filling space s. The pipe 58 includes a pressure-adjustment valve 60 for opening the pipe 58 when the differential pressure between the filling space s and the external space rises to a setting pressure or more.

(27) The storage space V.sub.1 formed inside the partition wall 50 stores the liquefied hydrogen LH.sub.2. An escape pipe 62 communicating to the storage space V.sub.1 is connected to the partition wall 52. The escape pipe 62 includes a safety valve 64 for opening the escape pipe 62 when the differential pressure between the storage space V.sub.1 and the external space reaches the setting pressure or more. The side wall 50a of the partition wall 50 is directly exposed to the external environment. Thus, the side wall 50a is mainly exposed to sunlight and reflection light from the earth, which results in inward penetration of radiation heat h. A fuel supply pipe 66 is connected to the storage space V.sub.1. The fuel supply pipe 66 is also connected to the combustor 68 of the rocket to supply the liquefied hydrogen LH.sub.2 to the combustor 68.

(28) The carbon nanotubes 56 adsorb and store in advance a low-boiling medium that has a boiling point equivalent to or less than that of the liquefied hydrogen LH.sub.2, such as hydrogen and helium. When the rocket travels the outer space and the differential pressure between the filling space s and the external space reaches the setting pressure or more, the pressure-adjustment valve 60 opens. Once the pressure-adjustment valve 60 opens and the pressure inside the filling space s decreases, the low-boiling medium adsorbed and stored in the carbon nanotubes 56 separates from the carbon nanotubes 56. Separation of the low-boiling medium involves an endothermic reaction, and thereby the liquefied hydrogen LH.sub.2 stored in the storage space V.sub.1 is cooled.

(29) According to the present embodiment, when the differential pressure between the filling space s and the external space reaches the setting pressure or more, the escape pipe 62 is automatically opened to cause an endothermic reaction, which makes it possible to cool the liquefied hydrogen LH.sub.2 in the storage space V.sub.1. Thus, it is possible to absorb the radiation heat h that is to about to penetrate into the storage space V.sub.1. As described above, the endothermic reaction of the carbon nanotubes 56 is utilized, which makes it possible to reduce the amount of evaporation gas from the liquefied hydrogen LH.sub.2 without providing an additional refrigerating device or the like. Further, when the pressure-adjustment valve 60 is opened and the low-boiling medium is completely discharged, the filling space s becomes a vacuum similar to the outer space, which makes it possible to secure a heat insulating property to a certain extent with the filling space s against the heat penetrating into the storage tank 10F. Alternatively, in the present embodiment, the pressure-adjustment valve 60 may be controlled to open and close by a control device.

Embodiment 7

(30) Next, the second embodiment of the second aspect of the present invention will be described with reference to FIGS. 8 and 9. The partition wall 50 of a storage tank 10G of the present embodiment includes an intermediate wall 70 made from metal between the inner wall 52 and the outer wall 54. A filling space s1 formed between the outer wall 54 and the intermediate wall 70 is filled with the carbon nanotubes 56, and a filling space s2 formed between the inner wall 52 and the intermediate wall 70 forms a heat insulating material layer 72 including a radiation heat insulating material. Other configuration is identical to that of the first embodiment.

(31) According to the present embodiment, the cooling effect of the carbon nanotubes 56 and the heat insulating effect of the heat insulating material layer 72 improve the cold-keeping effect for the liquefied hydrogen LH.sub.2 in synergy, which makes it possible to further reduce the amount of evaporation gas in the storage space V.sub.1. Further, providing the heat insulating material layer 72 inside the filling space s1 facilitates layout of the pipe 58.

Embodiment 8

(32) Next, the third embodiment of the second aspect of the present invention will be described with reference to FIG. 10. The partition wall 50 of a storage tank 10H of the present embodiment is different from that of the first embodiment of FIGS. 6 and 7 in that it includes a heat insulating material layer 74 including a radiation heat insulating material at the outer side of the outer wall 54. Other configuration is identical to that of the first embodiment. In the present embodiment, similarly to the first embodiment, the cooling effect of the carbon nanotubes 56 is achieved, and further, it is possible to enhance the cold-keeping effect for the liquefied hydrogen LH.sub.2 from the synergy of the above cooling effect and the heat insulating effect obtained by the heat insulating material layer 74, which makes it possible to reduce the amount of evaporation gas in the storage space V.sub.1. Moreover, since the heat insulating material layer 74 is disposed on the outer side of the carbon nanotubes 56, there is no intervening object between the carbon nanotubes 56 and the liquefied hydrogen LH.sub.2, which makes it possible to promote heat transfer between the carbon nanotubes 56 and the liquefied hydrogen LH.sub.2.

Embodiment 9

(33) Next, the fourth embodiment of the second aspect of the present invention will be described with reference to FIG. 11. A storage tank 10I of the present embodiment includes the first intermediate wall 70 disposed between the inner wall 52 and the outer wall 54, both of which are made from steel. Further, the filling space formed between the inner wall 52 and the first intermediate wall 70 is filled with the heat insulating material layer 72 including a radiation heat insulating material, while the filling space formed between the first intermediate wall 70 and the outer wall 54 is filled with the carbon nanotubes 56. Furthermore, a heat insulating material layer 74 including a radiation heat insulating material is formed on the outer surface of the outer wall 54. Other configuration is identical to that of the third embodiment.

(34) According to the present invention, since the heat insulating material layers 72, 74 each including a radiation heat insulating material are formed on the inner side and the outer side of the carbon nanotubes 56, respectively, it is possible to enhance the heat insulating effect remarkably as compared to the second embodiment and the third embodiment. Thus, it is possible to further reduce the amount of evaporation gas in the storage space V.sub.1 from the synergy of the two heat insulating material layers and the carbon nanotubes 56.

INDUSTRIAL APPLICABILITY

(35) According to the first and second aspects of the present invention, it is possible to provide a storage tank whereby it is possible to reduce the amount of evaporation gas from the low-temperature liquefied fuel stored in the storage tank, while restricting an increase in the weight of the storage tank.

REFERENCE SIGNS LIST

(36) 10A to 10I Storage tank 12, 42, 50 Partition wall 12a, 50a Side wall 14, 72, 74 Heat insulating material layer 16 Partition plate 18, 36, 44 Fin 20, 62 Escape pipe 22, 64 Safety valve 24 Main fuel pipe 24a, 24b, 66 Fuel supply pipe 26, 68 Combustor 30, 30A, 30B, 46 Heat pipe 32 Heating part 34 Cooling part 40 Container 52 Inner wall 54 Outer wall 56 Carbon nanotube 58 pipe 60 Pressure-adjustment valve 70 Intermediate wall LH.sub.2 Liquefied hydrogen SH.sub.2 Slush hydrogen V.sub.1 Storage space (first storage space) V.sub.2 Storage space (second storage space) s, s1, s2 Filling space