Drum for Transporting and/or Storing Batteries and the Use of such a Drum

Abstract

A drum for transporting and/or storing batteries, the drum having an internal storage space having a volume, and the drum being provided with a lid to close off the storage space The lid is provided with one or more openings for venting gas from the storage space to the atmosphere. One or more openings have a total surface area of at least 1.0 square centimeter per liter volume of the storage space. On an outside of the lid is at least one sheet of foil which covers a first group of two or more of said openings, in which the sheet of foil is connected to the lid completely around the first group of openings.

Claims

1. A drum for transporting and/or storing batteries, comprising: an internal storage space, the storage space having a volume; and a lid to close off the storage space, wherein the lid is provided with two or more openings for venting gas from the storage space to the atmosphere, and wherein on the outside of the lid at least one sheet of foil is present which covers a first group of the two or more openings, wherein the sheet of foil is connected to the lid completely around the first group of openings.

2. The drum of claim 1, wherein the sheet of foil is attached to the lid by being adhered to the outside of the lid.

3. The drum of claim 2, wherein the sheet of foil is a sticker with a cover layer, the cover layer being removed at the locations where the sheet of foil is attached to the lid.

4. The drum of claim 1, wherein the sheet of foil is designed to tear or to break if the difference between the pressure on the inside of the lid and the atmospheric pressure is greater is than a threshold value.

5. The drum of claim 1, wherein the sheet of foil has a first partial surface with which the sheet of foil is connected to the lid, wherein the sheet of foil has a second partial surface which is completely surrounded by the first partial surface, the second partial surface having a perimeter C and an area A, the foil having a tensile strength T, where C, A, and T have the units m, m.sup.2, and N/m, respectively, wherein the tensile strength T is determined in one of the two following ways: method 1) The tensile strength T is measured on the type of foil concerned; or method 2) A tensile strength X in units N/m.sup.2 is measured on the material from which the type of foil concerned is manufactured, and the tensile strength T is calculated by multiplying the tensile strength X by the thickness of the foil, wherein T <50000*(A/C) and preferably wherein T <30000*(A/C).

6. The drum of claim 5, wherein the second partial surface is not attached to the lid other than via the first partial surface.

7. The drum of claim 5, wherein the drum has a circular lid with a diameter (D) of 0.45 m or less, wherein (A/C) >0.035 m.

8. The drum of claim 1, wherein a layer of gas-permeable flame-retardant material extends accross the two or more openings, the flame-retardant material being made of steel fibers or mineral fibers.

9. The drum of claim 8, wherein the layer of flame-retardant material has a mass that is at least 0.75 grams per liter of volume of the storage space, whereby the average diameter of the steel fibers or mineral fibers is at most 0.5 mm.

10. The drum of claim 8, wherein the layer of flame-retardant material has a mass that is at least 0.75 grams per liter of volume of the storage space, whereby the average diameter of the steel fibers or mineral fibers is at most 0.5 mm.

11. The drum of claim 8, wherein the lid comprises at least four layers at the location of the two or more openings, wherein a first layer and a second layer are both provided with said two or more openings, wherein a third layer is formed by the layer of flame-retardant material, wherein the layer of flame-retardant material is provided between the first layer and the second layer, wherein a fourth layer is formed by the sheet of foil.

12. The drum of claim 11, wherein the first layer and the second layer are made of steel and are fixed to each other by means of clinching.

13. The drum of claim 1, wherein the drum comprises a drum body, the drum body containing the storage space, wherein the drum body is provided on its inside with an epoxy resin coating.

14. The drum of claim 13, wherein the lid is provided on its inside with an epoxy resin coating.

15. The drum of claim 1, wherein at most four of said sheets of foil are present on the outside of the lid, and preferably exactly one said sheet of foil.

16. The drum of claim 1, wherein the storage space is at least partially filled with batteries, wherein the storage space is closed off by the lid, wherein the quantity of batteries is at least 0.1 kg per liter volume of the storage space.

17. The drum of claim 1, wherein the foil is a plastic foil.

18. The drum of claim 1, wherein said two or more openings have a total surface area of at least 1.0 square centimeter per liter of volume of the storage space.

19. A method of storing and/or transporting batteries, wherein said batteries are placed in the storage space of the drum of claim 1.

20. A drum for transporting and/or storing batteries, comprising: an internal storage space, the storage space having a volume; and a lid to close off the storage space, wherein the lid is provided with one or more openings for venting gas from the storage space to the atmosphere, wherein a layer of gas-permeable flame-retardant material extends across the one or more openings, the flame-retardant material being made of steel fibers or mineral fibers, and wherein the lid comprises at least three layers at the location of the one or more openings, wherein a first layer and a second layer are both provided with said one or more openings, wherein a third layer is formed by the layer of flame-retardant material, wherein the layer of flame-retardant material is provided between the first layer and the second layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to clarify the invention, a preferred embodiment of a drum according to the invention is described below, with reference to the following figures, wherein

[0066] 1) FIG. 1 shows a perspective view of a drum according to the invention;

[0067] 2) FIG. 2 shows an exploded view of the drum of FIG. 1;

[0068] 3) FIG. 3 shows a part of the drum of FIGS. 1 and 2 in top view according to F3;

[0069] 4) FIGS. 4 to 6 illustrate successive states, shown in cross-section along IV-IV, in the manufacture of a part of the drum of FIGS. 1 and 2.

DETAILED DESCRIPTION

[0070] The drum 1 shown in the figures mainly consists of a cylindrical drum body 2 and a circular lid 3. The drum body 2 is mainly made of bent sheet steel and defines an internal storage space 4 for articles, in this case used batteries. The drum 1 is coated on its entire inside with a surface layer of epoxy resin with a thickness of about 9 μm.

[0071] The drum 1 has an external diameter of 35 cm and a volume of 53 liters.

[0072] The drum 1 is designed such that the drum 1 in a state where the lid 3 is mounted on the drum body 2 and secured with a tightening ring, can withstand an internal pressure of 50000 Pa above atmospheric pressure without damage.

[0073] The lid 3 consists of four main parts, i.e. four layers, i.e. from bottom to top, a bottom plate 5, a layer of steel wool 6 with a thickness of 10 mm, made of stainless steel or inox, a top plate 7, and a circular sheet of plastic foil 8 with a diameter D of 259 mm.

[0074] The top plate 7 is shaped to fit snugly on the drum body 2 and is similar to a traditional drum lid.

[0075] The underside of the bottom plate 5 is coated with the same surface layer of epoxy resin as the inside of the drum body 2.

[0076] The bottom plate 5 and the top plate 7 are each provided over a large part of their surface with a regular pattern of sixty-one circular openings 9, each with a diameter d of 16 mm. The openings 9 in the bottom plate 5 are located exactly below the openings 9 in the top plate 7.

[0077] The openings 9 have a total passage area of 61*0.25* π*(16 mm).sup.2, which corresponds to 118 cm.sup.2.

[0078] The steel wool 6 is made of fibers with an average diameter of 30 μm. The layer of steel wool 6 has a mass of 1200 g/m.sup.2 at said thickness of 10 mm, and a free volume between the fibers of 98.5 volume %. The layer of steel wool 6 has a diameter of 259 mm and a total mass of 63 g.

[0079] The sheet of plastic foil 8 is designed as a self-adhesive sticker with an adhesive layer and a cover layer 10 covering the adhesive layer, wherein the cover layer 10 is removed at the outermost 9 mm such that the adhesive layer of the sticker is exposed in an annular shape, and is adhered to the top plate 7 completely around the openings 9, but not between them.

[0080] As a result, the sheet of plastic foil 8 has a first partial surface 11 with an area of ((259 mm).sup.2-(259 mm-2*9 mm).sup.2)*0.25* π=7.07*10.sup.−3 m.sup.2 with which the sheet of plastic foil 8 is adhered to the remainder of the lid 3, and a second partial surface 12 with an area A of (259 mm -2*9 mm).sup.2* 0.25* π=45.6*10 .sup.−3 m.sup.2 with which the sheet of plastic foil 8 is not directly adhered to the remainder of the lid 3 and which extends over the openings 9.

[0081] The second partial surface 12 has a perimeter C of (259 mm -2*9 mm)* π=0.76 m.

[0082] When the cover layer 10 is disregarded, the plastic foil 8 has a thickness of 60 μm and is made of PVC with a tensile strength X of 19 MPa. Therefore, the sheet of plastic foil 8 has a tensile strength T of 19 MPa *60 μm=1140 N/m.

[0083] The plastic foil 8 has a dimensional stability, measured according to standard FINAT TM 14, of less than 0.1 mm in a transverse direction and less than the measurement threshold in the longitudinal direction.

[0084] The plastic foil 8 is provided with an adhesive layer with an adhesive force of 18 N/25 m, measured according to standard FINAT TM 1, after 24 hours, on stainless steel.

[0085] The lid 3 can be easily manufactured in the following manner, which is schematically shown in FIGS. 4 to 6.

[0086] First, the bottom plate 5 and the top plate 7, with the layer of steel wool 6 in between, are correctly positioned relative to each other.

[0087] Subsequently, by means of clinching, the top plate 7 and the bottom plate 5 are fixed to each other at four attachment points 13. The layer of steel wool 6 is hereby permanently fixed in a closed cavity 14 between the top plate 7 and the bottom plate 5. Clinching is a known technique in which point-shaped deformations of sheet material are made by cold pressing between two tools 15 formed for this purpose, in order thereby to make connections between sheet materials.

[0088] The situation before clinching is shown in FIG. 4, and the situation after clinching is shown in FIG. 5.

[0089] Subsequently, a custom-made sticker made of the plastic foil 8 and having a cover layer 10 is taken, the outermost 9 mm of the cover layer 10 is removed, and the sticker is adhered to the top plate 7. This is shown in FIG. 6.

[0090] The drum 1 can be used to collect used batteries at collection points, whether or not placed in a decorative casing.

[0091] When these batteries are to be transported to a processing location, the lid 3 is placed onto the drum body 2 and secured with a tightening ring, not shown.

[0092] The sheet of plastic foil 8 hereby prevents rainwater from entering the drum 1 during transport and/or storage, pending processing.

[0093] If the batteries in the storage area should ignite, internal pressure will be created due to the evolving gases and the increased temperature.

[0094] At a given moment, this will cause the sheet of plastic foil 8, at the transition between the adhered part and non-adhesive part, to tear, such that the gases can escape through the openings 9 and through the tear or tears that have developed in the sheet of plastic foil 8, before the drum 1 explodes.

[0095] The pressure at which the sheet of plastic foil 8 will tear can be calculated as follows, or at least can be approximated.

[0096] As described above, the plastic foil sheet 8 has a tensile strength of 1140 N/m, and the second partial surface 12, which is not adhered, has a perimeter of 0.76 m. This means that the plastic foil sheet 8 can withstand a total force on the second partial surface 12 of 1140*0.76=866 N before tearing.

[0097] Such a force is exerted if the pressure inside the drum times the area of the second partial surface 12, which is not adhered, is also 866 N. Since the area A of the second partial surface 12 is equal to 45.6*10.sup.−3 m.sup.2, the pressure at which this force is exerted is equal to 866N/45.6*10.sup.−3 m.sup.2, which is equal to 18985 Pa.

[0098] This is approximately a factor of 2.5 below the maximum pressure for which the drum 1 is designed, such that the sheet of plastic foil 8 will tear before the pressure in the drum 1 becomes too high.

[0099] The hot and possibly burning reaction gas which is formed during such an ignition of batteries flows through the layer of steel wool 6 and is cooled by the layer of steel wool 6, such that flames are extinguished by cooling by the steel wool 6 and no flames exit the drum 1.

[0100] As a result, the drum 1 is ideally suited for the safe transport of used batteries on a road vehicle or a rail vehicle and for the safe storage of used batteries, because no explosion of the drum 1 will occur and because no flames will exit the drum 1.

[0101] Because, due to the epoxy resin coating, no short-circuit can occur via the walls of the drum 1, it is not necessary to place a plastic inner bag inside the drum 1 before putting used batteries in it.