Fixed LPG tank

Abstract

 A fixed tank (1) for the storage of liquefied petroleum gas designed for an underground or surface installation outdoors is described. The tank (1) includes a tank casing (5) made of welded steel which defines an internal storage space which can receive liquefied petroleum gas. The fixed tank (1) includes a supply valve (20), a safety valve (21) and a filling valve, said valves being provided in order to establish a fluidic communication between the internal and external space, the safety valve (21) being adapted to reduce the pressure of the liquefied petroleum gas when said pressure exceeds a pre-set threshold value. The internal space has a storage capacity of between 200 litres and 450 litres including the ends.

Description

[0001] This invention refers to the technical field of storage tanks for fuels and particularly concerns a fixed storage tank for liquefied petroleum gases (LPG).

[0002] This patent application claims priority of patent application filed as number LT2011U000001 on 21 March 2011 which is fully incorporated for reference herein.

[0003] There are well-known cylindrical fixed storage tanks used to contain liquefied petroleum gas - LPG - with a minimum capacity of 500 litres and reaching a capacity of as much as 13,000 litres. The aforementioned fixed storage tanks in conventional practice are designed and built according to the EN Standard 12542:2010 (previously EN14075:2007). The spread of alternative energy (thermal solar, bio fuels, etc.), the improvement in the energy classes of buildings, and the constant increase in traditional fuel prices have effectively rendered the aforementioned tanks overestimated for the current needs of private users. In relation to the overestimation of the capacity of the aforementioned tanks, these tanks therefore represent a problem from the point of view of costs, dimensions and the difficulty in transport and installation. A further problem with the aforementioned tanks is linked to their disposal after use. Moreover, in accordance with the aforementioned EN Standard 12542:2010, the aforementioned tanks with a capacity over 500 litres, after installation at the destination site, must be obligatorily equipped with a fire prevention certificate issued by the fire brigade. In order to avoid the use of the large fixed tanks described above whilst having a suitable capacity in relation to consumption requirements, sometimes irregular and dangerous installations are created which include a variety of mobile LPG cylinders each up to 125 litres in capacity selectively connected to a domestic installation through a control exchange. In other cases, in order to satisfy capacity requirements there is a tendency to create dangerous stocks of mobile cylinders. In the case of mobile cylinders, if the capacity of the volume stored overall by the various cylinders exceed 150 litres it is necessary to have a fire prevention certificate issued by the fire brigade. In most cases this certificate is not requested. Therefore the need is felt to make available a fixed tank for LPG that compared to the large tanks in conventional practice guarantees a certain convenience of transport and installation, which guarantees a certain flexibility of installation, which is effective in relation to the changed needs for consumption and that at the same time prevents the creation of dangerous situations.

[0004] The aforementioned requirement is fully met through a fixed storage tank for liquefied petroleum gas as generally defined in claim 1. Preferred and advantageous embodiments of the aforementioned tanks are defined in the annexed dependent claims. The invention will be better understood from the following detailed description of its particular embodiments, as examples and therefore not restrictive, with reference to Figure 1 that shows a side elevation view of an embodiment of a fixed storage tank for liquefied petroleum gas.

[0005] With reference to Figure 1, reference number 1 globally indicates a fixed liquefied petroleum gas storage tank in accordance with a possible embodiment of the invention. In the particular example shown, this tank 1 is designed for a fixed underground installation, particularly inside a trench 3 dug below ground level 2.

[0006] In accordance with an alternative embodiment not shown in the figure, the fixed storage tank 1 is instead designed for an installation outdoors and on the surface.

[0007] For the purposes of this description, the fixed tank means a tank designed for a fixed installation in a set place and intended to be refilled in the set place of installation in contrast with the mobile cylinders designed to be refilled in a refilling centre or transported with vehicles during their normal use. The fixed tank 1 includes a tank casing 5 made of welded steel which defines an internal storage space which can receive liquefied petroleum gas.

[0008] The fixed tank 1 includes a supply valve 20, a safety valve 21 and a filling valve (not shown in the figures), said valves being provided in order to establish a fluidic communication between the internal and external space. The safety valve 21 is adapted to reduce the pressure of the liquefied petroleum gas when said pressure exceeds a pre-set threshold value. In accordance with an embodiment the aforementioned valves are contained in an inspectable chamber 6 equipped with a pivoted cover 10. Unusually, the internal space has a storage capacity of between 200 litres and 450 litres including the ends, and preferably below 300 litres. In the latter embodiments the tank 1 is classifiable as a fixed tank that in accordance with the aforementioned standard does not need a fire prevention certificate. In a particularly preferred embodiment, the storage capacity of the fixed tank 1 is equal to 295 litres.

[0009] In accordance with an embodiment, the fixed tank 1 also includes a liquid withdrawal valve 22 adapted to allow a rapid emptying of the fixed tank 1 for safe rendering. In accordance with an embodiment, the fixed tank 1 also includes an indicator, not shown in the figure, for measuring the level of liquefied petroleum gas contained in the internal space.

[0010] In the embodiment in which the fixed tank 1 is designed for an underground installation, the container casing 5 is externally covered with an epoxy resin and the fixed tank 1 includes a cathodic protection system 12, 13, 18 with at least one sacrificial anode 13. The cathodic protection system also includes a reference electrode 18 and an electrical box 12. Through this box 12 and through suitable conductors the sacrificial anode 13 is electrically connected (in the figure in the point indicated as 16) to the container casing 5 of the fixed tank 1. The cathodic protection system is not necessary in the embodiment in which the fixed tank 1 is designed for an installation that is not underground.

[0011] In accordance with an embodiment, the fixed tank 1 includes at least one pair of lifting eyebolts 9 permanently fixed to the outside of the container casing 5, for example welded to it.

[0012] In accordance with an embodiment, the fixed tank 1 also includes a plurality of basically U or L shaped support and fixing feet 7 welded to said container casing 5, the feet being adapted to permanently fix the tank 1 to an anti-overturning (in the case of an installation not underground) or anti-floatation (in the case of an underground installation) device 8. For example, this anti-overturning device 8 is a plate, or a slab, made out of reinforced concrete. For example, each of the feet 7 is equipped with a hole or a recess, not shown in the figure, for fixing through a hinge to the anti-overturning or anti-floatation device 8.

[0013] In accordance with a further embodiment, the container casing 5 includes a central cylindrical part 5c with a vertical axis, an upper cap 5b and a lower cap 5a, said three parts being welded together to form seals. In a particularly advantageous embodiment, the aforementioned three parts 5a, 5b, 5c of the container casing 5 are recycled parts obtained by cutting and reconditioning the respective portions from tanks with a capacity greater than or equal to 500 litres destined for disuse/disposal. In accordance with a particularly preferred embodiment, the fixed tank 1 is a cylindrical tank with a vertical axis having a diameter of about 80 cm and a total height of about 100 cm.

[0014] As is clear from the above description, the fixed tank 1 in accordance with this invention allows the proposed aims to be fully met. Obviously, a man skilled in the filed, in order to satisfy contingent and specific requirements, will be able to make numerous changes and variations to a fixed tank as described above, all moreover contained within the scope of protection of the invention, as defined by the following claims.

Claims

1. Fixed tank (1) for the storage of liquefied petroleum gas intended for an underground or surface installation outdoors, the tank (1) including a tank casing (5) made out of welded steel which defines an internal storage space adapted to receive liquefied petroleum gas, the fixed tank (1) including a supply valve (20), a safety valve (21) and a filling valve, said valves being provided in order to establish a fluidic communication between the internal and external space, the safety valve (21) being suited to reduce a pressure of liquefied petroleum gas when said pressure exceeds a pre-set threshold value, said internal space having a storage capacity of between 200 litres and 450 litres including the ends.

2. Fixed tank (1) according to claim 1, in which said storage capacity is below 300 litres.

3. Fixed tank (1) according to claim 2, in which said storage capacity is about 295 litres.

4. Fixed tank (1) according to any one of the previous claims, also including a liquid withdrawal valve (22) adapted to allow a rapid emptying of the fixed tank (1) for safe rendering.

5. Fixed tank (1) according to any one of the previous claims, also including an indicator for measuring the level of liquefied petroleum gas contained in said internal space.

6. Fixed tank (1) according to any one of the previous claims, wherein the tank is designed for an underground installation, wherein said container casing (5) is externally covered with an epoxy resin and wherein the fixed tank (1) includes a cathodic protection system with at least one sacrificial anode (13).

7. Fixed tank (1) according to any one of the previous claims, including at least one pair of lifting eyebolts (9) permanently fixed outside of said container casing.

8. Fixed tank (1) according to any one of the previous claims above, also including a plurality of basically U or L shaped feet for support and fixing (7) welded to the container casing (5), said feet being adapted to permanently fix said tank to an anti-overturning or anti-floatation device (8).

9. Fixed tank (1) according to any one of the previous claims, in which said container casing (5) includes a central cylindrical part (5c) with a vertical axis, an upper cap (5b) and a lower cap (5a), said three parts being welded together to form seals.

10. Fixed tank (1) according to claim 9, in which said three parts (5a, 5b, 5c) are recycled parts obtained by cutting and reconditioning the respective portions from tanks with a capacity greater than or equal to 500 litres destined for disuse/disposal.

11. Fixed tank (1) according to any one of the previous claims, wherein the tank is a cylindrical tank with a vertical axis having a diameter of about 80 cm and a total height of about 100 cm.

12. Fixed tank (1) as described above and shown in the attached figure and for the purposes specified.

Drawing