LIQUEFIED GAS STORAGE VESSEL FOR INTERMODAL TRANSPORT

Abstract

The liquefied gas tank for storage and distribution of liquefied gas is designed so that the outer 1 and inner tank 2 touch only through a fixed joint 5 and a sliding bearing 6 where the space 3 between the outer 1 and the inner tank 2 is filled with a material consisting of hollow microspherical particles of sodium borosilicate and synthetic silicon.

Claims

1. A liquefied gas storage and distribution tank, characterized in that the outer (1) and inner tank (2) touch only via a fixed connection (5) and a sliding bearing (6) and that the space (3) between the outer (1) and the inner a container (2) is filled with a material consisting of hollow microspherical particles of sodium borosilicate and synthetic silicon.

2. The liquefied gas storage and distribution tank according to claim 1, characterized in that the fixed connection (5) is made of sheet metal not more than 3 mm thick in the form of an elongated cone, while the sliding bearing (6) is made of two pipes of which pipe (7) welded on the outside of the floor of the inner tank (2) enters the pipe welded on the inside of the floor of the outer tank (8).

3. The liquefied gas storage and distribution tank according to claim 2, characterized in that the sliding part of the bearing (9) of the inner tank (2) rests on a non-metallic sliding material selected from the group consisting of but not exhaustive-commercially available polycarbonate materials and which is fixed to the inside of the tube (8) of the outer container (1).

4. The liquefied gas storage and distribution tank according to claim 1, characterized in that the hollow microspherical particles (4) of sodium borosilicate and synthetic silicon have an average particle diameter of less than 105 micrometres, a maximum particle diameter of less than 190 micrometres and a thermal conductivity of 0.0489 (W/mK), and a density of 0.08 g/cm3 or less.

5. The liquefied gas storage and distribution tank according to claim 4, characterized in that the hollow microspherical particles (4) of sodium borosilicate and synthetic silicon have a thermal conductivity of 0.0489 W/mK or less.

6. The liquefied gas storage and distribution container according to claim 5, characterized in that the ratio of sodium borosilicate to synthetic silicon is equal to or greater than 80:20 by volume, and in a preferred embodiment of the invention 90:10 by volume.

7. The liquefied gas storage and distribution tank according to claim 1, characterized in that the distance between the inner (2) and the outer tank (1) is at least 150 mm.

8. The liquefied gas storage and distribution tank according to claim 7, characterized in that a low thermal conductivity coating selected from the group consisting is applied to the outer shell of the outer tank.

9. An insulation method for liquefied gas storage and distribution tank, characterized in that microspheres are introduced into the space (3) between the outer (1) and inner tank (2) under low pressure by means of a high-volume injector, followed by vacuuming the space (3) via the vacuum valve (16) in three to four steps in such a way that the capacity of the vacuum pumps used from step one to the last step is reduced, followed by the insulation of the outside of the outer tank (1).

10. A liquefied gas storage and distribution container, insulated by the method according to claim 9.

Description

[0022] FIG. 1 shows a liquefied gas tank according to the prior art;

[0023] FIG. 2 shows a liquefied gas tank according to the invention;

[0024] FIG. 3 shows the results of a comparative test of the holding time duration of the solution according to the invention in relation to the holding times from the prior art;

[0025] FIG. 4 shows the results of the holding time solution according to the invention in relation to the holding time of sodium borosilicate glass and synthetic silicon.

CALL SIGNS HAVE THE FOLLOWING MEANING

[0026] 1external tank [0027] 2inner tank [0028] 3space between the outer and inner tank [0029] 4hollow microspherical particles [0030] 5fixed connection [0031] 6sliding bearing [0032] 7pipe welded on the outside of the dome-sphere of the inner tank [0033] 8pipe welded on the inner side of the dome-sphere of the outer tank [0034] 9sliding part of the sliding bearing of the inner tank [0035] 10non-metallic sliding material with low heat transfer coefficient [0036] 11dome-sphere of the inner tank [0037] 12dome-sphere of the outer container [0038] 13supports [0039] 14charging/irradiation opening [0040] 15charging/irradiation opening [0041] 16vacuum valve [0042] 17barrier against liquid splashing

[0043] Surprisingly, despite the teachings of Document EP 0 012 038, the present invention uses hollow microspherical particles 4 without plastic resins that prevent, i.e. delay the release of moisture, and contrary to expectations achieve better results in terms of length of holding time and heat leak, which is clearly shown in FIG. 3.

[0044] The holding time was also measured in case only sodium borosilicate in the form of hollow microspherical particles 4 is used as a thermal insulator in space 3 between the outer 1 and the inner tank 2 and it is 30 days. In case synthetic silicon holding is used as a thermal insulator, the time is even shorter. The results of the holding time for sodium borosilicate or synthetic glass in relation to the holding time according to the present invention are shown in FIG. 4.

[0045] The liquefied gas storage and distribution tank is designed in such a way that the outer 1 and the inner tank 2 touch only through a fixed joint 5 and a sliding bearing 6 where the space 3 between the outer 1 and the inner tank 2 is filled with a material consisting of hollow microspherical particles of sodium borosilicate and synthetic silicon. The fixed joint 5 is made of sheet metal not more than 3 mm thick in the form of an elongated cone, while the sliding bearing 6 is made of two pipes of which the pipe 7 welded on the outside of the dome of the inner tank 2 enters the pipe welded on the inside dome of the outer tank 8. As for the sliding part of the bearing 9 of the inner tank 2, it rests on a non-metallic sliding material whose heat transfer coefficient is very small and is fixed to the inner side of tube 8 of outer tank 1. Said non-metallic sliding material is selected from the group consisting of but not exhaustive-commercially available polycarbonate materials.

[0046] On the other hand, the hollow microspherical particles 4 of sodium borosilicate and synthetic silicon according to the invention have a mean particle diameter of less than 105 micrometers, a maximum particle diameter of less than 190 micrometers and a thermal conductivity of 0.0489 W/mK or less and a density of 0.08 g/cm3 or less. The hollow microspherical particles 4 of sodium borosilicate and synthetic silicon have a thermal conductivity of 0.0489 W/mK or less. The ratio of sodium borosilicate to synthetic silicon is equal to or greater than 80:20 by volume, and in a preferred embodiment of the invention is 90:10 by volume.

[0047] The above solutions allow the distance between the inner 2 and the outer tank 1 to be increased from 60-70 mm to above 150 mm. In a specific embodiment of the invention, the distance is increased to 152 mm.

[0048] In a particularly advantageous embodiment of the invention, a low thermal conductivity coating is applied to the outer shell of the outer tank, which represents a thermal barrier and therefore reduces the transfer of ambient temperature by convection to the liquefied gas tank.

[0049] Through two openings 14 and 15, the microspherical insulating material is poured. One of the openings is used for charging while the other is the irradiation opening. The function of the opening alternates with each loaded amount of 1 m.sup.3 of microspheres, all with the goal of their more even distribution in the insulation space. When the opening is in the function of a vent, then a filter system is mounted on it, both to save the insulating material that could come out in the venting process and to prevent environmental contamination with microspheres exiting through the vent space.

[0050] The transport of microspheres from the basic package in which the microspheres are delivered is carried out with low pressure and high volume injector in the presence of dry nitrogen gas, all to reduce moisture intake in the space 3 between the tanks. The injector sucks the microspheres from the delivery tank and transports them to the space between the tanks via nitrogen gas under pressure. Ultimately, due to the fluid characteristics of the microspheres and the loading process, the insulating microspheres completely and in a uniform density of 80 kg/m3 fill all the free space between the outer and inner tank. The loading and venting openings are hermetically closed after the microspheres are loaded.

[0051] The process of vacuuming the space 3 is carried out through a vacuum valve 16 installed on the formwork of the outer tank. Vacuuming is carried out in three to four steps, where the dynamics of vacuuming in terms of capacity and speed is strictly controlled to avoid the creation of moisture and thus frost in the vacuum space. In particular, from the first to the last step, the vacuuming is performed by using a maximum capacity vacuum pump in the first step and using smaller and smaller pumps through the steps to use the lowest capacity pump in the last step (third or fourth).