Container system

Abstract: The container system has at least two containers (2,3) each dimensioned to have a low external surface area to volume ratio. Connecting means (4) between the containers or between adjacent ones of the containers each comprise a tube adapted to fit within respective apertures in the containers to be connected. A sealing means (7) surrounds said tube 4 and is maintained in sealing engagement about the tube and apertures by compression between the containers joined by the connecting means.

Description: The present invention relates to a container system for storage of gaseous or liquid fluids. More particularly, but not exclusively, the invention relates to a container system comprising a number of interconnected containers whereby the total volume of the container system may be selected at will. The invention will be described with particular reference to its use in storage of detonating gas, produced by the electrolysis of water. However, many other uses can be foreseen and the present invention is not intended to be limited to any one particular utilisation. Detonating gas is manufactured by the electrolysis of water and comprises a mixture of hydrogen and oxygen. The mixture may be used to produce a useful flame. The mixture of hydrogen and oxygen is not particularly stable since the gases react explosively to reform water, especially in the presence of a catalyst. Accordingly, it is usual to produce the gas close to the time when it will be used, any storage means between the electrolytic generator and the burner being intended to form a reservoir where the detonating gas is stored at pressures in the range of 50 mbars (5 KPa) to about 250 mbars 25 KPa. The container system may also contain electrolyte, such as an acid or alkaline aqueous solution, used for the electrolytic generation of the gas and which is recycled from the container system to the generator and back again. As stated above, detonating gas is not always stable and under certain conditions the explosive gas mixture may be ignited, such as by catalytically active contamination carried in the feed water or by excessive temperatures within the cell. Any such explosions create an intensive high pressure shock wave, the intensity of which depends upon the storage gas pressure in the container. However, it is certainly sufficient to strain the construction of the container severely. Hence any container must have a comparatively high strength. Hitherto, containers have been manufactured as cuboids or as substantially cuboidal structures in which two of the faces are comparatively large but with high surface areas to dissipate the heat of the enclosed gas and liquid. These large surfaces are vulnerable to the high pressure shock waves caused by any such explosion. In order to withstand such explosions, the thickness of the material forming the container is normally between 1.5 to 4 mm, depending on the size of the container. It has hitherto usually been thought advisable to strengthen such a design, for example by adding bolts or stays to these large surfaces to absorb the forces of an explosion and thereby limit any deformation of the surfaces A spherical container is ideal from the point of view of strength, but suffers from heat exchange disadvantages. Thus, conventional container designs are disadvantageous from the view of possible explosions but they do have one advantage in that they provide a large surface area from which the heat of the electrolyte fluid may be dissipated. If the surface area of the container is reduced, the amount of heat which may be radiated from the surface of the container is correspondingly reduced. Since the electrolysis process produces hot electrolyte and hot gases, the heat exchange function of the container system is important to reduce the aggressiveness of the hot electrolyte and gases. It also serves to reduce the water vapour pressure and thereby reduce condensation in outlet pipes. Another reason for using comparatively large containers is to provide a sufficient amount of water fuel for the electrolytic generator to avoid the necessity of continual replenishment. In order to overcome some of the above difficulties, it would be possible to combine a number of containers, each having a low surface to volume ratio (i.e. cylinders or cuboids of square cross-section), connected together either in series or in parallel by means of external connections such as hoses. The connections of these hoses to the containers produce areas of weakness where any explosion may cause rupture of the container system. It is an object of the present invention to provide a container system which obviates the above disadvantages. Interconnected container systems are known in other technical fields. DE-C-656650 shows a system of interconnected spherical containers, for storing high pressure gas, in which the respective containers communicate via small orifices in a tube or connection plate. The purpose of this arrangement is to limit the rate of discharge of the gas in the event of a puncture. If one sphere is punctured, its own gas will be expelled quickly but the gas from the adjoining spheres will be expelled more slowly. Adjacent spheres are joined by welding. FR-A-1542467 discloses a system of two containers whose contents can be mixed on pushing them together. The containers are interconnected by a hollow tube which is normally closed at both ends. Sealing between the tube and the containers is by a very close friction fit between the two. According to the present invention there is provided a container system comprising at least two containers each dimensioned to have a low surface area to volume ratio, and connecting means between the containers or between adjacent ones of the containers, the connecting means each comprising a tube adapted to fit within respective apertures in the containers to be connected, characterised by resilient sealing means surrounding said tube positioned such that by compressing together the containers joined by the connecting means the sealing means is maintained in sealing engagement about the tube and the apertures. Preferably the tube comprises a first section of a first outer diameter and adapted to fit within an aperture of a first container and a second section of a second outer diameter greater than said first outer diameter and adapted to fit within an aperture of a second container, the internal diameter of said tube being, optionally, substantially constant. Alternatively, the tube may comprise a single section having substantially constant internal and external diameters. A flange may be provided about a median section of the tube, said sealing means comprising two sealing rings, one disposed between each container and the flange. The system may comprise a plurality of containers disposed one above another to form a stack. In this case, two or more such stacks may be disposed one along side another with lateral connections between at least some of the containers of each stack. In cases where the input to said system comprises a mixture of a gas and a liquid, the input connection to the system may be at an intermediate container, with gas passing therefrom to an upper container and liquid passing from the intermediate container to a lower one. In this case, separate outputs may be provided, one for gas and another for liquid. Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: FIGURE 1 is a cross-sectional view of a preferred shape of individual container, showing alongside one design approach for welding an end plate to the container; FIGURE 2 is a similar cross-sectional view showing an alternative approach to welding the end plate on the structure; FIGURE 3 is a cross-sectional view showing a connection between two containers of the system; FIGURE 4 shows a stack of containers with various interconnections between them; FIGURE 5 is a transverse cross-sectional view of the stack of containers; FIGURE 6 shows an alternative form of connection between two containers; and FIGURE 7 shows the connector of Figure 6 separately. Referring now to the drawings, each container of the system has preferably a rectangular shaped cross-section, as shown in Figures 1 and 2. Connections between containers in such a system may be made in either vertical or horizontal faces of the container, and the rectangular cross-section improves the "squeeze and seal" connection described in more detail below. Ends of the rectangular profile tube may be welded on either as shown in Figure 1 or as shown in Figure 2, the weld lines being indicated by numeral 1. Of the two, the embodiment shown in Figure 2 is generally preferred for its better welding conditions. Other methods may be used, for example by forging the end plates to close over the ends. Referring now to Figure 3, an upper container 2 is joined to a lower container 3 by means of a connector 4. The connector 4 comprises a tube of constant internal diameter but having a lower section 5 of reduced external diameter when compared with an upper section 6. The apertures in the containers 2 and 3 are differently sized, each corresponding to one of the external diameters of sections 5 and 6. It is preferred that the lower container 3 has the smaller sized aperture. In order to connect the containers, the tube connector 4 has its small diameter section 5 inserted in an aperture in the lower container 3 of corresponding dimensions. The tube connector 4 is pushed home, and the larger external diameter section 6 prevents the connector from falling into the container. An annular seal 7 is then placed around the tube connector 4 and the upper container 2 located with its lower aperture surrounding the large diameter section 6 of the tube connector 4. An outer rigid jacket (not shown) of length slightly less than that of the seal 7 may be placed around the seal. A series of such connections is seen in Figure 5, where the containers form a stack, each one connected to the adjacent ones in the stack. The entire stack may then be surrounded by metal straps and squeezed together so that the seals 7 secure the connections between containers. An alternative form of connector is shown in Figures 6 and 7 where the tube connector 8 is a cylinder of constant internal and external diameters. At a median point of the tube connector 8, a radially extending flange 9 is provided which is optionally connected to the tube connector 8. To assemble such connection, a pair of seals 7 surround the tube, one each side of the flange 9. An outer rigid jacket may also be provided in this case. The tube is then connected into apertures of equal diameter in containers 2 and 3 and the assembly squeezed together by means of metal straps or the like. The containers 2 may be connected permanently, for example by welding. The seals 7 may be made of any conventional resilient material, such as rubber or plastics material. For some applications, the seals 7 may even be made from soft metals, e.g. gold. Although not shown, it is possible for connectors either as shown in Figure 3 or as shown in Figures 6 and 7 to be used to connect containers in a horizontal or transverse direction. Referring now to Figure 4, there is shown a stack of four containers. The lowermost two are connected by means of a connection arrangement at each end of the container, while the uppermost three have connections at one end only but with metal spacers 10 at their other end so that the design is properly balanced. The spacers 10 may be of a material other than metal to allow the individual containers better to be thermally decoupled. In the arrangement shown, the output of an electrolytic generator is fed to the third container as shown by arrow 11. The mixture of detonating gas and water separates mainly in this container with the gas going upwardly to the fourth and uppermost container and the water passing downwardly to the first and second containers. As it does so, more gas separates from the liquid and finds its way upwardly. Detonating gas may be withdrawn at point 12 while water may be recycled to the electrolytic generator from points 13. Each container of the system has a low surface area to volume ratio, and is therefore more resistant to explosions of the mixture than would otherwise be the case. The connections between containers are also resistant to such explosions since they are of minimal length and are surrounded by a seal. However, the containers are separated one from another either by the connector or by a spacer 10 and thus there is, in total, a large surface area for heat exchange between the medium and the ambient atmosphere. The amount of water stored for use in the electrolytic generator may be increased simply by adding additional containers to the system. One further advantage of a system embodying the invention lies in the thermal decoupling of the individual containers. In a single large container, the gas and liquid will have approximately the same temperature. If the gas and liquid may be separated into different, but joined, containers, the gas should cool more quickly, an effect which increases if the gas occupies or passes through several thermally decoupled containers. Furthermore the gas flow may change direction when flowing from one container to another, and any entrained droplets of electrolyte may impact the internal surfaces and be removed from the gas flow. As stated above, the present invention is not directed exclusively towards containers for storage of detonating gas. It may be used to provide a high strength, high surface area vessel for any type of application, especially heat exchange applications, such as radiators, boilers and the like. The preferred shape of the containers is substantially square in cross section, although other shapes, such as cylinders may be used. Another advantage of the system, especially when used in the electrolysis of water to form detonating gas, is that the containers and connectors form sludge traps. In such a process, the electrolyte may be caustic potash solution which is recirculated by means of an electric circulation pump between the container system, where it is degassed and separated, and the electrolyser. Residues of the electrode materials may gradually build up and be carried around the system. This is true of nickel electrodes and even more so when the electrodes are of nickel coated steel. If the electric pumps are of the leak free type, there is a magnetic field which attracts magnetic particles, such as iron or nickel. These particles are attracted to slots in the pump and start to block it. This can cause overheating of the system and therefore detonation of the gas. However, since the connectors protrude into the containers, there is provided, at the base of such containers, a still zone in which sludge may settle. This effectively removes it from circulation, thereby improving the efficiency of the system.

Claims: A container system comprising at least two containers (2,3) and connecting means between the containers or between adjacent ones of the containers, the connecting means each comprising a tube (4) adapted to fit within respective apertures in the containers to be connected, characterised by resilient sealing means (7) surrounding said tube (4) positioned such that by compressing together the containers (2,3) joined by the connecting means the sealing means is maintained in sealing engagement about the tube and the apertures. A container system as claimed in claim 1, characterised in that the tube (4) comprises a first section (5) of a first outer diameter and adapted to fit within an aperture of a first container (3) and a second section (6) of a second outer diameter greater than said first outer diameter and adapted to fit within an aperture of a second container (2). A container system as claimed in claim 2 in which the internal diameter of the tube (4) is substantially constant. A container system as claimed in claim 1, characterised in that the tube comprises a single section having substantially constant internal and external diameters. A container system as claimed in any one of the preceding claims, characterised in that a flange (9) is provided about a median section of the tube, said sealing means comprising two sealing rings (7), one disposed between each container and the flange. A container system as claimed in claim 5 in which the flange (9) is connected to the tube connector. A container system as claimed in any one of the preceding claims, characterised in that said connecting means comprises a rigid outer jacket to surround the sealing means. A container system as claimed in claim 7, wherein the outer jacket has a length slightly less than that of the seal. A container system as claimed in any one of the preceding claims, characterised in that it comprises a plurality of containers disposed one above another to form a stack. A container system as claimed in claim 8, characterised in that two or more said stacks are disposed one alongside another with lateral connections between at least some of the containers of each stack. A container system as claimed in either claim 9 or claim 10, characterised in that where the input to said system comprises a mixture of a gas and a liquid, the input connection to the system is at an intermediate container, with gas passing therefrom to an upper container and liquid passing from the intermediate container to a lower one, the system preferably having separate outputs, one for gas and another for liquid. A container system as claimed in any preceding claim including means for compressing the containers together. A container system as claimed in claim 12 in which the compressing means comprise metal straps surrounding the containers.

Inventors: SPIRIG ERNEST, SPIRIG, ERNEST
Applicants: SPIRIG ERNEST, SPIRIG, ERNEST
Application year: 1991
Main classification: C25B15
IPC codes: F17C1, C25B15, B65D21, F17C13