EP0008949A1

EP0008949A1 - Intermittently-portable fuel storage and dispensing tank

Info

Publication number: EP0008949A1
Application number: EP79301835A
Authority: EP
Inventors: John Nevill Jackson
Original assignee: Petrofina UK Ltd
Current assignee: Total Downstream UK Ltd
Priority date: 1978-09-09
Filing date: 1979-09-06
Publication date: 1980-03-19
Also published as: GB2029373A

Abstract

The invention concens an intermittently-portable fuel storage and dispensing tank designed to provide optimum safety conditions. The tank basically consists of a double-skinned container, with inert insulating material entrapped between the two skins, and a surrounding housing reinforced to provide mechanical protection to the fuel container and to act as a bund therefore. Preferably the housing embodies a heat shield.

Description

This invention concerns a portable fuel storage and dispensing tank, and more particularly relates to an above-ground tank for petroleum products at a station providing a dispensing service for motor vehicles.
Traditionally, in many countries, storage of petroleum products at dispensing points is effected in tanks mounted beneath ground level, and only on very rare occasions, for instance temporary sites associated with an itinerant exhibition or on sites only used spasmodically, has above-ground storage been contemplated, mainly because of the increased hazard presented by such installations.
Modern day requirements, resulting from extension of the motoring population, the need for stations in remote parts, the increasing tendency to provide unmanned stations, and the temporary location of sites resulting from local conditions, such as show or exhibition sites or diversions resulting from large-scale construction or repair works, is likely to result in an increased demand for portable fuel storage and dispensing tanks. Local authorities are naturally and rightly concerned that sites embodying such above-ground tanks should have a high safety factor and this invention relates to a tank designed to exhibit this requirement.
According to the present invention an intermittently-portable fuel sotrage and dispensing tank comprises a double-skinned container rigidly mounted within a surrounding outer protective housing in the form of a bund which also embodies means for dispensing fuel from the container, the two skins of the container being spaced from one another, with an inert insulating material filling the space between the two skins, and the protective housing embodying reinforcing members to afford mechanical protection to the container.
Preferably the surrounding outer protective housing is carried on a supporting raft adapted for mounting on a suitable foundation laid at ground level.
Conveniently, if it is desired to store and dispense different grades of fuel, the inner of the two containers is divided into an appropriate number of compartments by one or more membranes, each compartment being provided with its own filling, dispensing and venting means. One or more pumps and auxiliary equipment, constituting the dispensing means, may be accommodated within the outer housing, in a chamber constructed with appropriate safety features.
The invention will now be further described by way of example with reference to the accompanying drawings, in which:-

Figure 1 is a side elevation, partly broken away for ease of illustration of a tank according to the present invention;
Figure 2 is a corresponding plan view;
Figure 3 is a vertical section taken along the line III-III of Figure 1;
Figure 4 is a schematic flow diagram applicable to the tank of Figures 1 to 3, and
Figure 5 is an enlarged detail, partly broken away through the end wall, roof and floor of the outer protective housing.

As shown by Figures 1 and 2 an intermittently-portable fuel storage and dispensing tank comprises a double-skinned fuel container 10 formed by an inner skin 12 defining the actual fuel storage volume and an outer skin 14 spaced from skin 12. The intervening space 16 is filled with an inert insulating material, such as that sold under the Mark "Perlite". In the illustrated embodiment the container 10 is divided centrally by a membrane 18 to provide two separate compartments 20 and 22 intended to contain differently rated fuels, i.e. one of a higher octane than the other. Obviously, by the provision of additional membranes or dividing walls, any desired number of separate compartments may be obtained and hence any number of different types or grades of fuel may be stored and dispensed. Both skins 12 and 14 are constructed from mild steel plate, and preferably skin 14 is thicker, possibly even twice as thick, as skin 12. For instance skin 12 may be manufactured from 6mm plate and skin 14 from 12mm plate with a spacing of 25mm between them for the inert insulating material.
Spaced from, and surrounding fuel container 10 is an outer protective housing 24 suitably braced with reinforcing members 26. Housing 24 may be prefabricated from mild steel plate, for instance 6mm plate. Container 10 is carried within housing 24 on mild steel cradles 28. Provision is made at one end of housing 24 for a chamber 30 to accommodate pumping and other equipment and access to this chamber is by means of lockable doors 32. This chamber 30 can also house filling and drainage connections, fire extinguishers and an electrical earthing connection. Housing 24 may be provided with a protective and/or decorative canopy 34. Valved drains 36 may be provided at each end of housing 24 and the whole unit may be carried on a supporting raft 38 resting on suitable foundations. One or more shielded or louvred air vents may be provided such as that shown in the end wall at the left of Figures 1 and 2.
Preferably the walls, roof and floor forming housing 24 constitute a heat shield to reduce the hazard due to accidental fire. Figure 5 shows a section through details of the junction between roof and wall as well as between wall and floor. It will be seen that the structural members 14 are lined internally with layers of expanded metal 76 sandwiched between flat metal sheets 78 and metal foil 80 having taped joints. This arrangement dissipates heat in the event of fire.
The unit can be transported as a module to any suitably prepared site.
Access to container 10 is through one of two lockable covers 40 in the roof of housing 24 which when opened reveal manhole tops 42 associated one with each fuel compartment 20 and 22 and lifting eyes 44. Air vents are provided in housing 24 to reduce internal condensation.
Conveniently housing 24 is provided with a motorway type crash barrier (not shown) around it to obviate possibility of damage in the event of a vehicle colliding with it.
The manholes 42 may each incorporate fill and drain connections as well as delivery, dip and vent. A spare connection may also be embodied.
A typical flow diagram is shown in Figure 4 wherein compartments 20 and 22 are shown schematically, dispensing from compartment 20 being by way of pipe 46 and from compartment 22 by way of pipe 48. Each of these pipes has a slam shut valve 50 operated by a fusible link (against fire hazard) and a magnetic valve 52 (to prevent syphoning) energised to open. Fuel is supplied from bulk delivery vehicle unloading point 54 through a screw down non-return valve 56 and a pump 58 (in chamber 30) to a 3-way valve 60 fed through a non-return valve 62. Operation of valve 60 determines whether fuel fed to the tank goes into compartment 20 by way of pipe 64 or to compartment 22 by way of pipe 66. Both pipes 64 and 66 have plugged drain connections 68. Vent pipes 70 from each fuel compartment terminate in pressure vacuum relief valves 72 (liquid shut out) because these vent lines must pass vapour only and shut off if liquid fuel attempts-to travel along them, for instance as a result of overfilling of either compartment. Although only a two compartment container is shown and described, the installation can be adapted for a greater number of compartments.
It is a general requirement that any container for dangerous liquids shall be mounted within or surrounded by.a bund, that is an outer retaining element which, in the event of damage to the container resulting in leakage of the liquid therefrom is capable of retaining the maximum contents of the container without spillage beyond the boundaries of the bund. In the construction described, the bund is formed by outer protective housing 24 which is internally sealed in its lower half, apart from drains 36, to a height such that the internal volume of that lower half is sufficiently great to retain the entire contents of both or all compartments of container 10 in the event of rupture or other damage thereto. In other words, the internal volume of housing 24, up to say the lower edge of doors 32, is in excess of the maximum capacity of a container 10 (more specifically of the compartments 20 and 22 defined by inner skin 14).

Claims

1. An intermittently-portable fuel storage and dispensing tank comprising a double-skin container rigidly mounted within a surrounding outer protective housing in the form of a bund which also embodies means for dispensing fuel from the container, the two skins of the container being spaced from one another, with an inert insulating material filling the space between the two skins, and the protective housing embodying reinforcing members to afford mechanical protection to the container.

2. An intermittently-portable fuel storage and dispensing tank as claimed in claim 1 wherein the outer protective housing is carried on a supporting raft adapted for mounting on a suitable foundation laid at ground level.

3. An intermittently-portable fuel storage and dispensing tank as claimed in claim 1 or 2 wherein the container volume defined by the inner of the two skins is divided into a plurality of separate compartments by one or more membranes or dividing walls, each compartment being provided with its own filling, dispensing and venting means.

4. An intermittently-portable fuel storage and dispensing tank as claimed in any one of claims 1 to 3 wherein a chamber with appropriate safety features is provided within the outer housing for the accommodation of one or more pumps and auxiliary equipment.

5. An intermittently-portable fuel storage and dispensing tank as claimed in any preceding claim in which both skins of the container are formed from mild steel plate, the inner skin being thicker than the outer one.

6. An intermittently-portable fuel storage and dispensing tank as claimed in any preceding claim in which the lower part of the outer housing is sealed to prevent liquid leakage therefrom up to a height defining a volume in excess of the maximum total capacity of the double-skin container.

7. An intermittently-portable fuel storage and dispensing tank as claimed in any one of claims 1 to 6, wherein the housing is provided internally with a heat shield.

8. An intermittently-portable fuel storage and dispensing tank as claimed in any preceding claim in which a crash barrier is provided around the outer housing.

9. An intermittently-portable fuel storage and dispensing tank substantially as herein described with reference to and as illustrated in the accompanying drawings.