Double-walled tank container

Abstract

The present invention concerns a double-walled tank container (1, 12, 13, 14) whereby the inner container (2, 3) is stored at the bottom inside the outer enclosure (6) by a spacer consisting of several spacer pieces (16). The spacer provided, which is preferably placed near a front saddle ring (12, 13), imparts transportation and storage stresses between the inner tank (2, 3) and the outer enclosure (6) and consequently between the inner container (2, 3) and the frame (14) of the tank container. The spacer (16) can be laid out in such a way that it absorbs shocks and/or defines a hollow space (10). This hollow space can serve as a thermal insulation or for the installation of temperature equalization devices, mediums or a leak detector fluid.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present patent application claims priority from German Patent Application No. DE 202 15 657.5, filed on Oct. 11, 2002.

[0002] Certain applications require the use of double-walled tank containers. In this case, an inner container is more or less completely enclosed by an outer container. These designs are necessary when the container needs to be extremely leak-proof, such as, for example, when the interior plate is brittle and the inner tank requires a high degree of protection against exterior impacts, or needs to be completely protected by a liquid temperature equalization medium. The leak-proof character often needs to be further increased by filling the space between the outer and inner tank with a non-hazardous test liquid thus revealing possible leaks in both the inner as the outer tank

[0003] It is expedient that the outer containers of such tank containers can be incorporated in proven and standardized frame constructions customary for single-walled containers. Ring saddle mountings, such as described in DE 32 12 696 C2, have proven to be worthwhile in the field of tank containers. In this design, the tank is connected with the front frames via the vaulted end arcs of the tank. This construction enables the stress between the tank and the frame, which occurs during handling and transportation of the tank containers, to be completely imparted. Other connections between the tank and the frame are generally not necessary.

[0004] FIG. 4 shows a known design of a front ring saddle mounting on a double-walled container, whereby a front ring (12′) runs through the exterior bottom plate (8′, 8″) and is welded to the interior bottom plate (3′). This requires separating the exterior bottom plate and running a piece (8′) around the interior bottom plate (3′) back to the front ring (12′), as well as mounting an exterior bottom piece (8″) in the front ring (12″). This procedure is unsatisfactory from a production viewpoint and unsuitable for inner containers with a brittle interior bottom plate since the stresses from transportation and handling directly work on the tank plate covered with the coat. Increasing the wall thickness of the entire inner container, or at least the end bottom plates of the inner container, can offset this. This would increase the weight of the tank considerably.

[0005] Furthermore, this design does not guarantee that the container will be leak-proof and increases the production cost. The front ring (12′) needs to be interrupted in the area where it is connected with the interior bottom plate in order to enable the hollow space (10′) inside the front ring to interconnect with the hollow space (10′) outside the front ring, and to allow a leakage detector liquid to run through it. Furthermore, there is a risk that a leak (3″) in the area of the welding between the front ring (12′) and the interior bottom plate is not shown because possible double sheet metal plating (12″) in the front ring might cause the leak to seep out through the exterior bottom plate (8′, 8″) without activating the leakage detector.

[0006] The present invention aims at fastening an inner tank in the defined position in an outer enclosure, enabling stresses and strains to be imparted between the inner tank and the frame without having to interrupt the outer enclosure in the strain transmission areas. Furthermore, it aims at realizing low-cost production measures to leak-proof the container, and making light inner containers with brittle interior coats available for tank containers.

[0007] The solution to this problem consists of a tank container as described in claim 1 whereby the inner container is fixed lengthwise inside an outer container connecting the latter to the front frame in a conventional way with a front ring saddle mounting. Since the vaulted interior and exterior bottom plates have a process tolerance, it is impossible to install the inner container inside the outer container without compensating these process tolerances. The spacer also solves this problem.

[0008] The enhanced design in accordance with claim 2 makes it easier to install the outer tank around the inner tank.

[0009] claims 3 and 4 cover extremely expedient designs and layouts of the spreader(s) for ring saddle mounted tank containers. Spacers composed of several spacer blocks allow for a very precise tolerance compensation between the interior and exterior bottom plates. The conical design not only compensates the stresses running in the direction of the tank axle, but also radial and vertical stresses, and imparts them to the front ring mounted directly between the interior and the exterior bottom plates in accordance with claim 4.

[0010] claim 5 covers an enhanced design whereby the inner tank does not have to be completely encompassed by the outer tank. This is the case when the outer tank serves as a leakage safety device and therefore only needs to reach the maximum filling height of the inner tank.

[0011] claim 6 covers a tank container whereby the outer enclosure completely encompasses the inner enclosure and the connections attached to the inner enclosure can penetrate the outer enclosure. The design described in claim 7 covers putting a leak detector liquid or a heating or cooling medium in the hollow space allowing a thorough rinse of the clearance.

[0012] The designs covered by claims 8 and 9 mainly concern tank containers with a coated inner container. In this case, shock-absorbing spacers connect the inner container with the outer container. High-resistance PUR/PIR foams especially allow for a very smooth stress transition in the inner container. Filling the space between the inner and the outer tanks with foam enhances this effect, and allows for extremely thin-walled, light yet coated inner containers. For this, the outer container needs to be closed completely. The design described in claim 10 allows for the installation of a heating element between the inner and outer enclosure. This requires appropriate spacers are required. The heating element either heats the inner tank directly or the temperature medium between the inner and outer enclosure.

[0013] The drawings below illustrate preferred construction examples. In these drawings:

[0014] FIG. 1 shows a partial side view of a tank container according to the invention with a schematic presentation of the front frame.

[0015] FIG. 2 shows a detail of the front ring saddle mounting according to the invention.

[0016] FIG. 3 shows a side view of the tank container end with a coated inner tank and shock-absorbing spacers.

[0017] FIG. 4 shows a detailed view of a conventional front ring mounting of a double-walled container.

[0018] According to the invention shown in FIG. 1, the end of the container has a double-walled tank 1 with an inner tank composed of a cylindrical center section 2 and an interior bottom plate 3 connected via the welding 4. Both the tank section 2 and the interior bottom plate 3 are concentric with respect to the tank axle 5. Furthermore, the double-walled tank has an outer enclosure 6 encompassing a cylindrical section 7 and an exterior bottom plate 8. Both parts 7, 8 are also concentric with the tank axle 5 and are connected via the welding 9.

[0019] The cylindrical section 7 presented only partially encompasses the tank section, thus keeping the apex area uncovered. This design is expedient when the inner container 2, 3 only needs to be encompassed up to its maximum filling height instead of being encompassed completely. The clearance 10 between the inner tank 2, 3 and the outer tank 7, 8 is welded shut.

[0020] A cylindrical front ring 12 and a corner iron saddle ring 13 connect the exterior bottom plate 8 with the frame (not shown) equipped with a front frame 14. Welded joints 15a through 15f (FIG. 2) connect the front frame 14, saddle ring 13, front ring 12 and the exterior bottom plate 8.

[0021] Spacer pieces 16 create the clearance between the exterior bottom plate 8 and the interior bottom plate 3. A conical arrangement of the rings makes the spacers concentric with respect to the tank axle of the outer surface of the interior bottom plate 3 and the inner surface of the exterior bottom plate. The spacers are located in the area of the welded joints 15e and f, thus allowing the stress imparted over the front ring 12 to be imparted through the exterior bottom plate over the spacer pieces 16 on the interior bottom plate 3. Thanks to the conical arrangement, the stress can be imparted in the direction of the tank axle, as well as in a radial direction of the tank axle. The design example shows spacer pieces 16 attached with spot welding to the interior bottom plate 3. It is also possible to attach the spacers to the inner surface of the exterior bottom plate 8.

[0022] The size of the spacer pieces 16 determines the size of the hollow space 10 and also offsets the process tolerance of the interior and exterior bottom plates 3, 8 in such a way that the inner tank 2, 3 is clamped between the exterior bottom plates.

[0023] When the tank container is in use, the hollow space 10 serves as a leakage control devise. For this purpose, the hollow space 10 is completely filled with a harmless test liquid and connected in an interconnecting way with a compensator reservoir (not shown) placed above the apex of the tank. The connection in the apex of the tank (not shown) is laid out in a shell type arrangement 7c. The filling level of the compensator reservoir can be checked through an inspection glass or an extra level indicator. In case of a leakage in the inner tank 2, 3, the test liquid enters the inner tank and the gauge in the control reservoir drops. Changes in the filling level are determined with regular checkups or by an audio and/or video signal.

[0024] The hollow space 10 can also be used for the circulation of a liquid or gaseous temperature equalization medium. The temperature of this medium is controlled by a connected aggregate (also not shown).

[0025] FIG. 3 shows a design with very thick spacer pieces 16a creating a very large hollow space 10. These spacer pieces 16a consist of a shock-absorbing material (high resistance PUR/PIR, elastomers, plastics, etc.) creating an energy absorbing, buffering elastic force coupling between the inner tank 2, 3 and the outer enclosure. In the pictured design, the cylindrical section 7 of the outer enclosure 6 completely encompasses the inner tank 2, 3 and is composed of the reference cylinder shell segments 7a and 7b, welded together and to the exterior bottom plate 8 in an overlapping design. This layout is extremely suitable for inner tanks 2, 3 with a brittle interior coat (not shown) necessary for very aggressive freights. The elastic floating arrangement of the inner tank 2, 3 in the outer enclosure 7a, 7b, 8 avoids strains causing rips in the coat. The hollow space 10 may be additionally filled with so-called high-resistance PUR/PIR. This increases the protective capacity of the inner tank 2, 3. At the same time, this creates a considerable thermal insulation effect, which is very useful for the transportation or storage of temperature equalized freights.

[0026] A possible design for this type of freight consists of a temperature equalization unit installed in the hollow space 10 between the inner tank 2, 3 and the outer enclosure 6. This temperature equalization unit could be made of half pipes, a resistance heating element or other temperature control devices welded to the inner tank. Other variants on the proposed invention can consist of using one single spacer as a conical ring or a concave disk between the interior bottom plate 3 and the exterior bottom plate 8 instead of individual spacer pieces 16. This is useful in long containers to impart stresses in a radial direction to the tank axle 5 between the inner tank 2, 3 and the outer enclosure 6.

[0027] The shock-absorbing spacer pieces 16a may also come as liquid-filled cases or flexible tubing for construction with a very large hollow space 10. With this type of spacer pieces 16a and filling of the hollow space 10, the inner container 2, 3 can be stored so safely that it can even be made of a brittle material such as glass.

Claims

1. Tank container with a double-walled tank (1) connected on both sides by a vaulted interior and exterior bottom plate (2, 8), whereby the outer tank enclosure (6) is connected with a frame (14), characterized by a spacer placed on one end between the exterior bottom plate (8) and the interior bottom plate (3).

2. Tank container as described in claim 1, whereby the spacer is attached (in particular welded or glued) to either the interior or the exterior bottom plate (3, 8).

3. Tank container as described in claim 1, whereby the spacer is composed of several spacer pieces (16, 16a) and/or is placed in a conical ring arrangement concentric with respect to the tank axle and following the exterior of the interior bottom plate and the interior of the exterior bottom plate, respectively.

4. Tank container as described in claim 1, whereby the spacer is located inside a front ring (12), which is part of a front saddle mounting (12, 13) and connected with the exterior bottom plate (8).

5. Tank container as described in claim 1, whereby the cylindrical section of the outer enclosure (7) between the exterior bottom plate (8) and the inner tank (2, 3) encompasses only in part in a lower area.

6. Tank container as described in claim 1, whereby the outer enclosure (6) completely encompasses the inner tank (2, 3) and is attached to the inner tank (2, 3) only with spacers.

7. Tank container as described in claim 1, whereby the hollow space (10), which is defined by the spacers or spacer pieces (16, 16a), between the outer enclosure (6) and the inner tank (2, 3) is filled with a test liquid or a temperature equalization medium.

8. Tank container as described in claim 1, whereby spacers or spacer pieces (16, 16a) made of a shock-absorbing material and the hollow space (10) between the inner tank (2, 3) and the outer enclosure (6) are filled with a second material. The first material includes in particular of high-resistance PUR/PIR, elastomers and plastics, and the second material includes of PUR/PIR border foams.

9. Tank container as described in claim 1, whereby the interior of the inner tank (2, 3) is equipped with a coat, in particular a phenolic resin or vitreous enamel coat, or the inner tank (2, 3) is made of a brittle material, in particular glass.

10. Tank container following claim 1, whereby the clearance between the inner and outer enclosure is equipped with a temperature equalizing devise.