WO2002030757A2

WO2002030757A2 - Variable volume container for a liquified gas fluid

Info

Publication number: WO2002030757A2
Application number: PCT/AU2001/001284
Authority: WO
Inventors: Andrew Coventry
Original assignee: BANTIX Pty Ltd
Current assignee: BANTIX Pty Ltd
Priority date: 2000-10-11
Filing date: 2001-10-11
Publication date: 2002-04-18
Anticipated expiration: 2003-04-11
Also published as: WO2002030757A3; AUPR069900A0

Abstract

A container 10 for a liquefied refrigerant such a liquid CO2 includes a bladder 12, a first valve14 in fluid communication with the bladder 12 and a pair of rigid plates 16 between which the bladder 12 is located. The plates 16 are biased toward each other by springs 28 to minimise the volume of the bladder 12. A girdle 18 is provided about the bladder 12 and has a maximum volume which is less than a burst volume of the bladder 12. The biased plates 26 act to minimise the volume of the bladder 16 when its contents are discharged from valve 14 thereby limiting the volume of a void or space within the bladder 12 into which the liquid contained therein could otherwise boil. This action further allows essentially full recovery or consumption of the liquid within the bladder 12.

Description

Variable Volume Container For A Fluid

Field of the Invention

The present invention relates to a variable volume container for containing a fluid and, in particular, but not exclusively, for containing a liquefied refrigerant gas under pressure.

Background of the Invention

The holding and storing of high pressure gases or liquid is generally confined to large heavy cylinders made from a ductile metal or alloy capable of withstanding internal pressures of up to two thousand pounds per square inch. Consequently, these cylinders are difficult to handle and to move and do not pack easily for transport and storage.

Typically, when a liquefied gas, (ie a gas under sufficient pressure that at least a part of its volume is in the liquid phase) is stored the common practice is to fill a cylinder of the type described above to about two-thirds of its volume with liquid, leaving the last third as free space to accommodate volumetric expansion arising from the liquid changing phase to a gas. As liquid is drawn from the cylinder the liquid occupied volume within the cylinder decreases thereby increasing the volume of the gas space within the cylinder and also reducing gas pressure within the cylinder. This results in a further portion of the liquid changing phase to a gas thus reducing the amount of liquid obtainable from the cylinder.

In addition, because of the material from which the cylinders are made, ambient temperature is transmitted to the contents of the cylinder. As the temperature increases, a portion of the liquid changes phase to a gas thereby decreasing the volume of liquid available to the cylinder.

Summary of the Invention

It is an object of the present invention to provide an alternate form of container for holding a fluid.

According to the present invention there is provided a container for a fluid including at least:

a bladder; a first valve in fluid communication with said bladder; and means for compressing said bladder.

Preferably said compressing means includes one or more substantially rigid elements defining a space in which said bladder is located and means for acting on said one or more elements to minimise said space.

Preferably said one or more substantially rigid elements includes two opposed plates or grids defining said space and said means is a bias means acting to bias said plates or grids together.

Preferably said container further includes a girdle surrounding said bladder and disposed within said compressing means, said girdle expandable to a maximum volume which is less than a burst volume of said bladder, said burst volume being a maximum volume to which said bladder can inflate prior to bursting.

Preferably said girdle is substantially non-elastically expandable.

Preferably said girdle is permeable to said fluid.

Preferably said girdle is made from a chain mesh.

Preferably said container includes a tube extending into said bladder and said first valve is coupled to an end of said tube outside said bladder, said tube provided with an internal passageway in fluid communication with said first valve and at least one opening in fluid communication between said passageway and an interior of said bladder.

Preferably said container further includes a second valve coupled at a second opposite end of said tube outside said bladder.

Preferably said container further includes a thermally insulating housing within which said bladder and compressing means are located and on the outside of which said first valve is disposed.

Brief Description of the Drawings

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 is a schematic representation of an embodiment of the variable volume container; and,

Figure 2 is a representation of the housing of the container depicted in Figure 1.

Detailed Description of Preferred Embodiment The drawing shows an embodiment of the container 10 for a fluid such as liquid CO₂ and includes a bladder 12, a first valve 14 in fluid communication with the bladder 12, and compressing means or device 16 for compressing the bladder 12.

The bladder 12 is made from a fluid impermeable material and advantageously, but not necessarily, is made from an elastic material. For example, the bladder 12 can be made from rubber or a plastics or polymer material. The walls of the bladder 12 can also be constructed, or the material from which the bladder is made selected, so as to provide a thermal barrier.

A girdle or outer guard bag 18 surrounds the bladder 12. The purpose of the girdle 18 is to limit the inflation or volume of the bladder 12. Specifically, the girdle 18 is configured so that it can expand to a maximum volume which is less than a burst volume of the bladder. The burst volume of the bladder being the volume to which the bladder inflates immediately prior to bursting. In this way, the girdle 18 acts to protect the bladder 12 from overfilling and bursting. To this end, the girdle is substantially non- elastically expandable. This characteristic can be achieved for example by making the girdle 18 from a chain mesh, a non-elastic textile material, or a carbon fibre polymer sheet. It is beneficial if the girdle 18 is also permeable to the fluid contained in the bladder 12. This can be achieved either by the provision of apertures through the girdle 18, such as would exist if the girdle were made from a chain mesh or a textile mesh, or could be provided by forming holes in the material from which the girdle 18 is made if that material is otherwise impermeable.

The valve 14 is coupled to the bladder 12 by way of a tube 20. The tube 20 extends into and wholly through, the bladder 12. To prevent leakage of fluid, the bladder 12 is sealed onto the tube 20 at locations where the tube 20 passes through the bladder 12. The valve 14 is coupled to one end of the tube 20 exterior of the bladder 12. The tube 20 is provided with an internal fluid flow path (not shown) and one or more holes 22 that provide fluid communication between the fluid flow path and the inside of the bladder 12. The fluid flow path of the tube 20 is also in fluid communication with valve 14. A second valve 24 is coupled to an opposite end of the tube 20 outside of the bladder 12. The provision of two valves allows one valve to be used for filling the bladder 12 with a fluid from a supply while the other valve can be coupled to a device that consumes the fluid contained in the bladder 12.

The compressing means 16 includes a pair of substantially rigid spaced apart elements in the form of plates 26 between which the bladder 12 is disposed. Springs 28 act on the plates 26 in a direction so as to reduce the distance or space between the plates 26. As such, the plates 26 and springs 28 act to compress the bladder 12. This in turn acts to decrease the interior volume of the bladder 12. Thus, as the contents of the bladder 12 is consumed the volume of the bladder 12 is simultaneously reduced.

The container 10 further includes a housing 30 in which is disposed the bladder 12, girdle 18, and compressing means 16. The valves 14 and 24 however are located on the outside of the housing 30. Ideally, the housing 30 is made from a thermal insulating material or panels. A pressure relief valve 32 is provided in the housing 30 to release pressure from the housing 30 in the event that the bladder 12 bursts. In the illustrated embodiment, the housing 30 is rigid, however this is not essential. The housing 30 could be in the form of a fabric bag.

Figure 2 depicts one possible embodiment of the housing 30 in the form of a substantially hexagonal prism, made of a rigid material and disposed within an integrated square tubular carry frame 34. The valves 14 and 24 extend through diametrically opposed diagonal surfaces 36 of the housing 30, but are within the boundary defined by the frame 34. Respective covers 38 are provided for covering the valves 14 and 24 when not being operated. The covers 38 are typically pivoted along one edge to the frame 34 so that they can be flipped open and closed. The covers 38 are in the general shape of a triangular prism which, when closed (ie covering an associated valve) extends coplanar with the portion of the frame 34 extending about the diagonal surfaces 36. The covers 38 are also provided with one or more (only one shown) slots 40 through which a hose (not shown) connected to an associate valve can extend when the cover 38 is closed. The hose may then extend through an adjacent "loop" formed by the portion of the frame 34 extending about the diagonal surface 36. The pressure relief valve (not shown in Figure 2) may be in the form of a "pop out" valve provided in the housing 30.

The operation and method of use of the container 10 will now be described. When the container 10 is empty, the plates 26 squash the bladder 12 flat so that the bladder 12 defines a minimum volume. To fill the container 10 with a fluid such as liquid CO₂, valve 14 is shut and valve 24 is coupled to a supply of liquid CO₂. The CO₂ passes through valve 24, tube 20 and hole 22 into the bladder 12. As the bladder 12 inflates it volume increases and the pressure of the fluid in the bladder 12 pushes the plates 26 apart against the bias of springs 28. The girdle 18 also expands accommodating the inflating bladder 12. When the desired volume of liquid CO₂ is contained within the bladder 12, the valve 24 is shut and the supply of liquid CO₂ is disconnected from the container 10. During the filling process, the girdle 18 will expand to define a maximum volume less than the burst volume of the bladder 12 to assist in preventing the bladder 12 from bursting.

The container 10 can then be connected to a device that uses or consumes liquid CO₂. The coupling can be via either valve 14 or valve 24. When the valve in question is opened, the liquid is able to flow through the holes 22, tube 20 and the selected valve 14 or 24 to the connected device. As the liquid CO₂ is consumed, the volume of the bladder 12 is reduced by action of the plates 26 and springs 28 which compress the bladder 12. If the bladder 12 is made of an elastic material, then the bladder itself will also assist in reducing its internal volume as the liquid CO₂ is consumed.

Because the volume of the bladder 12 decreases commensurate with the consumption of the liquid CO₂ the creation of a "void or space" within the bladder 12 into which the liquid CO₂ could otherwise boil to effect a gaseous phase change is avoided or at least its volume is substantially reduced. This further maintains the pressure of the liquid CO₂ within the bladder 12 to allow substantially full recovery or consumption of the liquid phase within the bladder 12.

The housing 30 also assists in reducing adverse effects of ambient temperature on the contents of the bladder 12. Should a leak develop in the bladder 12 be it either a slow leak or a catastrophic leak caused by bursting of the bladder 12, the contents of the bladder will fill the space enclosed by the housing 30. The pressure relief valve 32 will activate when the pressure within the housing 30 reaches a predetermined level thereby safely venting the contents to the atmosphere.

Now that an embodiment of the present invention has been described in detail it will be apparent to those skilled in the relevant arts that numerous modification and variations may be made without departing from the basic inventive concepts. For example, the compressing means 16 may take forms other than that illustrated in the accompanying drawing. For example, when the housing 30 is made from a rigid material, one of the plates 26 can be removed leaving one plate 26 and associated springs 28 for compressing the bladder 12 against the inside surface of the housing 30. In another variation, the plates 26 and springs 28 can be replaced by a spring metal spiral wound sleeve in which the bladder 12 is disposed. This is effectively squeezing the bladder 12 to a minimal volume when the bag 12 is empty, with the bladder 12 expanding the sleeve circumferentially as it is filled with the fluid. Further, it should be noted that embodiments of the container 10 can operate satisfactorily with only one of the valves 14 and 24. In addition, the tube 22 can be either deleted altogether so that the valve couples directly to the bladder 12 or alternately, the tube 20 may extend only partway through the bladder 12.

Also such modifications and variations are deemed to be within the scope of the present invention the nature of which is to be determined from the above description and the appended claims.

Claims

The claims defining the invention are as follows:

1. A container for a fluid including at least:

2. The container according to claim 1 wherein said compressing means includes one or more substantially rigid elements defining a space in which said bladder is located and means for acting on said one or more elements to minimise said space.

3. The container according to claim 2 wherein said one or more substantially rigid elements includes two opposed plates or grids defining said space and said means is a bias means acting to bias said plates or grids together.

4. The container according to any one of claims 1 to 3 further including a girdle surrounding said bladder and disposed within said compressing means, said girdle expandable to a maximum volume which is less than a burst volume of said bladder, said burst volume being a maximum volume to which said bladder can inflate prior to bursting.

5. The container according to claim 4 wherein said girdle is substantially non- elastically expandable.

6. The container according to claim 5 or 6 wherein said girdle is permeable to said fluid.

7. The claim according to any one of claims 5 to 7 wherein said girdle is made from a chain mesh.

8. The container according to any of claims 1 to 7 further including a tube extending into said bladder and wherein said first valve is coupled to an end of said tube outside said bladder, said tube provided with an internal passageway in fluid communication with said first valve and at least one opening in fluid communication between said passageway and an interior of said bladder.

9. The container according to claim 8 further including a second valve coupled at a second opposite end of the tube outside said bladder.

10. The container according to any one of claims 1 to 9 further including a thermally insulating housing within which said bladder and compressing means are located and on the outside of which said first valve is disposed.