Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D83/00—Containers or packages with special means for dispensing contents
  • B65D83/14—Containers for dispensing liquid or semi-liquid contents by internal gaseous pressure, i.e. aerosol containers comprising propellant
  • B65D83/60—Containers for dispensing liquid or semi-liquid contents by internal gaseous pressure, i.e. aerosol containers comprising propellant with contents and propellant separated
  • B65D83/62—Containers for dispensing liquid or semi-liquid contents by internal gaseous pressure, i.e. aerosol containers comprising propellant with contents and propellant separated by membranes, bags or the like
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C11/00—Use of gas-solvents or gas-sorbents in vessels

Definitions

• Containers of gas are required for a large number of different applications, ranging from the need to store particular gases for identification and calibration purposes to paramedical uses.
• Gas containment may be needed for simple propellaiicy or pressure regulation requirements or to impart the unique property of the stored gas.
• a container of compressed air may be used for dust removal from a computer keyboard or camera lens or it can be used as an emergency device to enable one to escape from a smoke-filled room, carriage or cabin.
• a container of compressed oxygen may be used so that the gas can be inhaled for therapeutic or other purposes.
• the application of oxygen is known to speed recovery following dental treatment.
• Other applications for containers of gas can be envisaged, such as flammable gases for welding, brazing or soldering in DIY or extinguishant gases, for example carbon dioxide, for extinguishing small fires.
• Further container-dispenser devices use compressed gases, such as hydrocarbons, that are charged to a can containing a bag of a fluid active ingredient whereby actuation of a valve provided in the can causes the gas to press on the bag and force the ingredient out from the can.
• compressed gases such as hydrocarbons
• discharge of the active ingredient tends to tail off as the pressure in the can falls resulting in non- uniform and inefficient dispensation of the ingredient.
• hydrocarbons that are volatile organic compounds is environmentally unfriendly.
• a further object of the present invention is to provide a storage container for a gas that, amongst other benefits and advantages, enables a greater volume of gas to be stored in a container of a given volume.
• Yet a further object of the present invention is to provide a method of discharging fluids from a storage container that does not require the use of volatile organic compounds and allows a more uniform and efficient discharge of the fluid.
• Still a further object of the present invention is to provide an improved container-dispenser device that does not require the use of volatile organic compounds to dispel the contents from the container and provides a more uniform and efficient discharge of the contents.
• a second aspect of the present invention provides a storage container for a gas, the container comprising a sealed vessel containing an amount of activated carbon having the stored gas adsorbed thereon.
• a storage container for a gas comprising a sealed vessel containing an amount of activated carbon having the stored gas adsorbed thereon.
• Any gas or mixture of gases that may be adsorbed by activated carbon may be stored according to the present invention but the method and container is particularly suitable for the storage of oxygen, carbon dioxide, nitrogen or air.
• the gas is stored in the container at a pressure less than or equal to 2000000 Pascal (20 atmospheres or bars). More preferably, the pressure is 400000 - 1600000 Pascal (4-16 bar).
• the container should be provided with a significant amount of activated carbon to increase the amount of gas that may be stored in the container and to increase the weight of the container.
• the activated carbon fills at least 40% of the internal volume of the vessel, more preferably at least 50%, especially at least 75%.
• the container should be provided with a valve assembly to allow gas to be inserted into and dispensed from the container.
• a filter is provided between the activated carbon in the container and the valve, such as a high efficiency particulate air filter.
• oxygen is adsorbed on to the activated carbon.
• a high activity carbon is used for adsorbing oxygen i.e., one having activity above 60% CTC (carbon tetrachloride).
• carbon dioxide is adsorbed on to the activated carbon.
• a lower activity carbon is used, i.e. having less than 100%o CTC, more preferably less than 60%, especially less than 50%.
• solid carbon dioxide is provided for adsorption on to the activated carbon. It has been found that this neutralizes any heat affect.
• the present invention also relates to the use of a container as herein described for the storage of a gas or a mixture of gases.
• the gas is stored in as large a quantity as possible within the container for its later use in applications that the particular gas is suitable for.
• oxygen may be stored for later inhalation for therapeutic or sport enhancement purposes.
• Further applications include emergency escape devices (e.g. face masks) and traps for pests such as rodents wherein stored carbon dioxide is released inside a trap to cause death of the rodent without undue suffering or causing environmental damage.
• Carbon dioxide may also be utilised as a storage atmosphere for bread or other perishable product (contained, for example, in a suitably designed box) since it is known than an atmosphere at least partially enriched in carbon dioxide helps to preserve bread enabling it to be stored for longer periods than when it is stored in air.
• the malleable enclosure is plastically open to the forces of the gas released from the activated carbon whereas the outer container is rigid with respect to these forces.
• the third and fourth aspect of the present invention are particularly suitable for storing and dispensing carbonated beverages.
• FIG. 1 of the accompanying drawings illustrates the components of the container according to one embodiment of the present invention.
• a cylindrical container 2 is part- filled (generally being at least 50% full) with activated carbon.
• a valve assembly 4 is then crimped to the top of the container and the gas to be stored therein is charged to the container.
• the valve is also provided with a filter 6 to prevent any dust from the carbon from exiting the container upon dispensing the gas.
• Activated carbons consist of a range of carbonaceous materials that have been specifically treated to develop an extensive capacity for the adsorption of a wide variety of gases and liquids. Such carbons may be derived from a host of sources and any type of activated carbon may be utilised in the present invention. However, for practical and commercial reasons the raw materials tend to be confined to, for example, peat, wood, coal, nutshell (such as coconut), petroleum coke and bone. Synthetic sources, such as poly(acrylonitrile) or phenol-formaldehyde, are also used for the production of activated carbon. Other sources include bamboo shoot, drupe stones and seeds.
• Numerous methods for activation of carbon exist in the art and may be used for providing activated carbon for the present invention.
• gaseous activation using steam, carbon dioxide or other gases at elevated temperatures is used, or chemical activation using, for example, zinc chloride or phosphoric acid.
• the activation process is used to develop an intricate network of pores of various sizes ranging from macroporous (>50 nm) to sub-microporous dimensions of molecular-sized entities.
• the larger pores are known as transport pores and these serve to provide access to the smaller pores in which most of the adsorption of gaseous species takes place.
• This unique pore structure, and the large surface area developed as a result provides the extensive physical adsorption property and the highest volume of adsorbing porosity of any substance known.
• Activated carbons have an enormous range of commercial applications. They have been used, amongst others, for odour control, NOC abatement, propellants, flue gas treatment, protection of nuclear installations, gold recovery, solvent recovery, decolourisation, catalysis, water treatment and as the adsorbent for respirators used in civil and military filters for the removal of noxious gases. However, activated carbons have not previously been used in relation to the production of gas storage containers as described herein.
• the present invention is suitable for the storage of any gas that may be adsorbed on to activated carbon.
• Table 1 illustrates the total volume of gas stored by a 1 litre container filled with activated carbon of high volumetric capacity at room temperature for seven different gases over various pressures. The corresponding volume contained by the compressed gas, in the absence of the activated carbon, is provided for comparison.
• Activated carbons of various types, origins, densities, activities and mesh sizes were used for the study.
• an empty aerosol-type can 400 cm 3
• a valve was crimped to the can and oxygen, at a pre-set pressure (12 bar, 1200000 Pascal), was charged to the can via the valve to constant weight.
• the uptake. of oxygen was typically more than double the quantity that would have occupied the same can at that pressure.
• the ratio of the weight of oxygen contained in the carbon- filled can to the weight of oxygen in the same volume of can, without any added activated carbon, is given as the Benefit Factor in Table 2 below. Table 2
• HEP A filter high efficiency particulate air-filter
• the capacity of oxygen or other gas in the can is increased by a factor of two or more (see Table 2). This enables the can to be provided in a smaller, more portable size.
• the increased weight of the can gives the consumer a strong perception of extra product and hence more value.
• Any extraneous smells associated with the processing of the product is retained by the activated carbon.
• the activated carbon imparts an improved static (physical) equilibrium to the can.
• the activated carbon assists in retaining the pressure within the can thereby maintaining efficient and uniform delivery of the gas from the can as the contents are depleted.
• the storage capacity of compressed gas from air and gas storage compressors is enhanced by the use of activated carbon.
• a vessel fitted with activated carbon can store 3 times more compressed air than, for example, a classical air vessel.
• the load on the compressor is itself reduced.
• the can may be provided with an adapter piece, for example in the form of a mask or mouth and/or nose piece for fitting over the mouth and/or nose of the user.
• an adapter piece for example in the form of a mask or mouth and/or nose piece for fitting over the mouth and/or nose of the user.
• the adapter may be provided with a series of holes to enable the piece to be flushed with the- stored gas prior to the user then breathing in the gas.
• This type of face or nose mask is preferable to prior art gas masks which only filter out particular chemicals.
• the present invention allows the user to breathe in pure oxygen or air from the can thereby removing the need to breathe in air from the atmosphere which may not have the harmful chemical filtered out sufficiently to render the air safe.
• Carbon dioxide is another example of a gas whose storage in a container may be enhanced by the presence of activated carbon. Carbon dioxide can have an extraordinarily high uptake on activated carbon. Values as high as about 250 g litre "1 of carbon have been recorded at 16 bar gauge pressure (1600000 Pascal) where the corresponding compressed gas weight would be only 29 g in a 1 litre volume.
• Such high-density gas storage may be employed for all manner of applications, particularly for an innocuous, non-flammable, low toxicity and environmentally neutral material. Examples of such applications include aerosol propellants, working fluids and pressure regulating devices.
• the degree of CO 2 uptake on activated carbon is normally regarded as a function of the level of activity to which the carbon has been subjected; the more highly activated carbons showing an increased propensity to adsorb more carbon dioxide as the microporosity and surface area increases.
• the percentage activity of the activated carbon is measured in terms of its ability to adsorb carbon tetrachloride (% w/w) by saturating the carbon's pores with CTC.
• Figure 4 is a generalisation of the above finding and illustrates that CO 2 adsorption increases approximately linearly with increase in the carbon's bulk density in the range of interest for carbons of the same generic type.
• the present invention enables a sufficient amount of carbon dioxide to be stored in a suitable container to talce advantage of the properties of the carbon dioxide other than its propellant properties, such as its ability to carbonate beverages or to conveniently extinguish small fires.
• low activity carbons should be used for adsorption of the carbon dioxide for storage of gas in these lower pressure containers, rather than high activity carbon that would normally be considered to provide maximum adsorption of the gas.
• Example 3 Use of Carbon Dioxide adsorbed on Activated Carbon in Dispensing fluid from a container.
• a pressure regulating device for dispensing a variety of active ingredients (such as shaving gel and hair treatment products) from a container uses a so-called “bag-in-can” or “bag-on- valve” system wherein a pressurized gas surrounds the bag containing the active ingredient to force the ingredient from the bag upon actuation of a valve.
• a pressurized gas surrounds the bag containing the active ingredient to force the ingredient from the bag upon actuation of a valve.
• chlorofluorocarbons CFCs
• products are generally dispensed by a mixture of hydrocarbons, for example, isopentane, isobutane and propane mixtures .
• Such mixtures in certain proportions, provide a convenient pressure regulating fluid with a room temperature vapour pressure that is suitable for the steady and complete discharge of the active ingredient.
• hydrocarbons do have a number of drawbacks, such as being toxic, highly flammable, greenhouse gases, volatile organic compounds and geopolitically sensitive. Additionally, cans containing these hydrocarbons are difficult to recycle owing to the flammable residues.
• the present invention employs carbon dioxide adsorbed on activated carbon as the pressurized gas.
• Carbon dioxide is non-toxic, non-flammable and does not fall within the definition of a volatile organic compound.
• Carbon dioxide is derived from natural sources or as a by-product of a large combustion plant. Thus, at worst it has minimal contribution to global warming and may actually sequestrate carbon dioxide from the enviromnent. It is ubiquitously available and is not politically or territorially sensitive.
• the conventional hydrocarbon fluid contained in a standard bag-in- can system was removed by disengaging the grommet located at the base of the can and allowing the vapour to escape to atmosphere.
• the can was then charged with activated carbon which had previously been saturated with carbon dioxide gas.
• An additional amount of carbon dioxide gas was then charged to the can such as to give a total pressure of 5 bar gauge after equilibrium between the adsorbed and gaseous phases.
• the grommet was replaced immediately after charging the carbon dioxide.
• Solid carbon dioxide or dry ice was used to provide the adsorbed carbon dioxide since this has been found to counteract any exothermic reaction. This is particularly important if large quantities of cans are being filled as otherwise repeated cooling and charging of the can would be required.
• valve of the can was then actuated and the dispensing characteristics of this device containing carbon dioxide was compared with an originally manufactured device containing the traditional hydrocarbon mix.
• the mode and rate of dispensation of the active ingredient from the modified device was noted to be indistinguishable from that of an original can. Discharging of the active ingredient was continued until cessation. On subsequent examination of the device, it was confirmed that the gas still contained excess gas pressure and that the inner bag had been completely emptied.
• adsorbed carbon dioxide gas in this manner instead of compressed gas has a number of benefits.
• Compressed gases require excessive pressures to be used to accommodate the volume of gas required to discharge the contents of the bag. Additionally, there is a rapid and unsatisfactory fall in pressure when compressed gas is employed. This means that too much of the active ingredient is ejaculated at initial actuation and too little discharged towards the end.
• adsorbed carbon dioxide gives only a small, almost indiscernible, pressure decrease at the end of the discharge resulting in a steadier flow of product.
• the delivery profile is very different. The important parameter is the volume of gas delivered per unit of pressure drop.
• the principle described in the example above could be employed from the dispensing of carbonated beverages from a bag-in-can system, as illustrated in Figure 5 of the accompanying drawings.
• the system would employ a large volume of can, for example, 5 litres, for home consumption.
• the device would comprise a 5 litre can 10 within which is a plastic enclosure 12 containing beer or other carbonated beverage 14, the device having a grommet 16 at the base thereof.
• a dip-leg 18 attached to an actuating valve 20 serves to ensure that only beverage is dispensed from the device via a dispensing tube 22.
• a space 24 surrounding the plastic enclosure is filled with carbon dioxide adsorbed on activated carbon.
• the activated carbon optionally pre-saturated with carbon dioxide, and additional carbon dioxide, is charged to the vessel in a manner hereinbefore described.
• This device according to the present invention ensures a smooth flow of beverage is dispensed until its discharge is complete.
• the beverage also remains in a fresh and carbonated condition because the volume of the bag enclosure tracks the volume of the remaining liquid and no gas headspace can be effectively generated.
• any gas that can be adsorbed by activated carbon may be stored in a low pressure container according to the present invention.
• Adsorbed nitrogen has similar advantages to carbon dioxide for use as an aerosol propellant or pressure regulating device but, more activated carbon is required to adsorb a similar quantity of nitrogen relative to carbon dioxide at a given pressure.
• a typical comparison, using carbon of a moderately high activity, is illustrated in Figure 6 of the accompanying drawings.
• it may be preferable to use nitrogen for example it may be seen to be more environmentally friendly or it may be less pemieable to the plastic enclosure.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)

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Citations (8)

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• 2004
  • 2004-12-02 WO PCT/GB2004/005045 patent/WO2005054742A1/en not_active Ceased
  • 2004-12-02 EP EP10192296.1A patent/EP2327921B1/de not_active Expired - Lifetime

Patent Citations (8)

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