[0001] This invention relates to a gas delivery device and to a method of delivering gas
using the device.
[0002] The controlled delivery of gases is important in many technical fields. For example,
temperature regulation by air conditioning is based on the delivery or air of a predetermined
temperature into a room. Also, many chemical reactions require the delivery of gas
into a reaction vessel and it is often desirable to have the gas provided as a fine
dispersion of small bubbles into a liquid reaction mixture in order to maximise the
rate of the reaction.
[0003] It is known that large enclosed spaces, such as exist in factories, can be heated
by blowing hot air into an extended tube of fabric located near to their ceilings.
The hot air permeates through the fabric and thereby heats the surrounding air inside
the enclosed space. Since the body of fabric into which the hot air is blown is large
and tubular, there is no direction of the hot air towards a particular location. Indeed,
the very purpose of the arrangement is to ensure that hot air is emitted in all directions
to give uniform heating of the surroundings.
[0004] WO-A-93/09388 discloses a device for dispersing air or a fire-extinguishing gas in
an enclosed space.
[0005] GB-A-2146114 describes the use of cool air to regulate the temperature of a vehicle
seat. The air is provided to the inside of a seat having an apparently conventional
seat cover with a relatively high gas permeability of 200 to 1000 cm
3/cm
2/s. The cavity for the air is provided by a rigid frame structure which makes this
system inflexible and relevant only to this specific type of application. Also, this
high level of porosity makes even distribution of the cool air over the whole of the
seat cover practically impossible.
[0006] There exists a need for a gas delivery system which is capable of delivering a uniform
flow of gas in a defined direction at a predetermined rate but which can be made relatively
light and versatile and is inexpensive. The present invention provides such a device.
[0007] Accordingly, the present invention provides a gas delivery device (1;6) comprising
an inlet (3; 12) for gas and two sheets (4;7,8) of woven, knitted or non-woven fibres
arranged as a double layer, one sheet (7) having a portion which is gas permeable
and the sheets being joined such that at least a part of the region (2;10) between
the sheets is capable of being inflated by gas directed through the inlet (3;12) and,
when inflated, of allowing the gas to permeate out of the device through the gas permeable
sheet (4;7), characterised in that the other sheet (8) is substantially gas impermeable.
[0008] The sheets may be of woven, knitted or non-woven fibres but are preferably woven.
The terms woven, knitted or non-woven, as used herein, cover all methods of constructing
an article from fibres, threads or yarn. The fibres may be of ceramic material, which
is particularly appropriate when the device is used in a high temperature environment
(e.g., greater than 250°C) but are preferably of organic polymeric material such as
polyamides (e.g., nylon), aramids (e.g., Kevlar
R), polypropylene, polyester, acrylics (e.g., polyacrylate or polymethacrylate), cellulose
or any other material which may be produced as a fibre. The fabric preferably has
a weight of from 50 to 300 g/m
2.
[0009] The sheets may be made by conventional means well-known in the art. They may be formed
as a roll of fabric which is subsequently cut to the desired lengths. The double layer
arrangement of the sheets may be achieved by forming each sheet separately and then
joining them by, for example, stitching, sealing, heat fusing or using an adhesive,
at suitable places along the length of the double layer sheet. Alternatively, the
two sheets may be formed and joined together simultaneously by conventional double
layer weaving or double layer knitting methods.
[0010] One of the sheets has at least a portion which is gas permeable. The permeability
of the sheet is chiefly due to the pores between the fibres (e.g., in the threads)
which make up the sheet. Preferably, the permeability is within the range from 0.1
to 1000 dm
3/m
2/s, more preferably 1 to 100 dm
3/m
2/s. Typically, the whole of the sheet, where not adhered to the other sheet in the
double layer, will be gas permeable. However, when used in the device of the invention,
the sheet may be treated or joined to the other sheet such that only a portion of
it is gas permeable. The degree of permeability of the sheet after it has been formed
may be suitable for many applications and it may not therefore require further treatment.
However, if the permeability of the sheet needs to be reduced for a given application,
this can be achieved by treating the sheet such that a proportion of the pores between
the fibres become partially or completely blocked. Blocking of the pores in this way
may be carried out by methods which are well-known in the art such as treatment with
an aqueous dispersion of a polymer (e.g., PVC, polyacrylate or polyurethane) or transfer
coating with a permeable polymer film.
[0011] One of the sheets is substantially impermeable. Such an arrangement has the advantage
of allowing gas to be delivered from all (or part) of one face of the double layer
sheet only. The ability to direct gas in this way is a clear advantage of the invention.
The sheet which is substantially impermeable may be formed initially in the same way
as the gas permeable sheet and subsequently treated with a material which renders
the sheet substantially impermeable. Treatments to render the sheet impermeable include,
for example, coating the sheet with an impervious coating of a polymer (such as a
film of polyurethane, polyethylene or polypropylene) which may be applied to the sheet
using an adhesive either directly or indirectly by transfer from a release paper.
Alternatively, the substantially impermeable sheet may be formed separately from the
permeable sheet and may be made substantially impermeable by increasing the density
of the fibres in the fabric and/or reducing the size of the pores.
[0012] At least a part of the region between the sheets in the double layer may be inflated
by gas directed through the inlet. Inflation of the region, which has a limited permeability,
causes a back pressure to the gas supply and ensures that the delivery of gas from
the device is substantially uniform throughout the whole of the part of the gas permeable
sheet or sheets which bound the inflated region. It also allows the device to act
as a cushion for an article which is placed on or near to the surface of the device.
The sheets may be made resiliently deformable by, for example, the use of a proportion
of elastomeric fibres such as Lycra
R, but this is not essential for the operation of the invention.
[0013] The device comprises an inlet for gas which directs gas to the region between the
sheets. Gas may be supplied by any means of providing gas at a pressure greater than
atmospheric pressure such as a compressor or a cylinder of pressurised gas. If the
device has more than one gas delivering region, the inlet may comprise a manifold
arrangement for directing gas from a single supply to each of the gas-delivering regions
of the device.
[0014] The nature of the gas which is delivered by the device will depend on its intended
use. The gas may consist of a single element or compound or may comprise a mixture
of two or more elements or compounds. Reactive gases (such as hydrogen or the halogens)
may be provided into the liquid phase of a chemical reaction. Alternatively, the device
may be used to supply relatively inert gases (such as argon and the other noble gases,
carbon dioxide or nitrogen) to provide an inert gas atmosphere. Gases might also be
delivered to plants to control their growth or their ripening e.g., carbon dioxide
which can speed up the growth rate of plants such as tomatoes.
[0015] In another application, the device of the invention may be used in a spurge system
for the scrubbing of air. Soiled air is pumped into the device by way of the gas inlet,
with the device being present within a tank of aqueous cleansing solution. The air
permeates out of the device as a fine dispersion of bubbles enabling efficient cleansing
of the air by the cleansing solution.
[0016] The device may also be used to regulate the temperature of an article or a region
by a method which comprises delivering gas of a predetermined temperature. For this
application, the gas is preferably air. A particular application of the device is
in maintaining comestible products (such as packaged or unpackaged foodstuffs) at
a temperature below room temperature (e.g., -10 to 10°C). Conventionally, the transport
of comestible products within a food processing or packaging facility, for example
on a conveyor belt, has caused difficulties since it has been necessary either to
transport the products quickly through an area which is at room temperature (which
may be undesirable as regards the perishability of the product) or to keep the whole
of the area at a reduced temperature (which is undesirable for an area in which people
need to work). The device of the present invention overcomes these problems since
it allows cold air to be supplied directly to the product and its immediate surroundings
and therefore need not significantly affect the environment outside this zone. Since
the device of the invention can be made light and flexible, it may itself form the
conveyor belt on which the food is transported. Alternatively, one or more than one
of the devices of the invention can be disposed above a conventional conveyor belt
to direct cold air at the product. The device or devices may also be disposed above
or below a conveyor belt which allows air to pass through it by, for example, being
made from a chain-type arrangement. The device has the advantage of greatly reducing
the tendency for moisture from the surrounding warmer air to condense onto the foodstuff
or its packaging.
[0017] Another example of temperature regulation using the device of the invention is in
the delivery of relatively warm or cold air directly to the human or animal body by
making a garment comprising a device of the invention with the gas permeable sheet
facing the skin.
[0018] The device of the invention, in one preferred embodiment, is a double layer of the
sheets, sealed at its edges and having an inlet for gas to allow gas to pass into
the device and between the sheets. In use, gas passes through the inlet and inflates
the region between the sheets. The gas permeates through the permeable sheet or sheets
and the pressure of the gas coming into the device at the inlet is then adjusted to
achieve a steady state i.e., a substantially constant rate of flow of gas into the
device and rate of flow of gas out of the device. The sheets may be kept substantially
parallel, when inflated, by means of monofilaments between the sheets which can be
included when the device is manufactured, using conventional technology.
[0019] In another preferred embodiment of the invention, the device is formed from two sheets
of fabric with alternate bands of the sheets being joined together (for example, either
by being woven, sealed or adhered to each other) and being unconnected, along or across
the direction of production of the fabric. The regions in which the sheets are unattached
are connected to an inlet for gas at one edge of the sheet and are sealed at the opposite
edge (again, for example, by being woven, heat sealed or adhered to each other). When
gas is passed through the inlet into the device, the unattached regions inflate to
provide a structure which resembles a series of connected parallel tubes. In a variation
on this embodiment of the invention, a proportion of the unattached regions (for example,
every other region) may contain a substantially rigid material, such as foamed rubber,
to provide extra support for an article placed on the device. Alternatively, a proportion
of the unattached regions may contain a porous material, such as an open cell foam.
The use of a porous material allows gas at a reduced pressure to be connected to these
unattached regions of the device, preferably by means of a non-collapsible tube (i.e.,
a tube which will not collapse under the reduced pressure) with apertures along its
length which extends through the centre of the porous material, and thereby permits
at least a proportion of the gas emitted from the device to be recovered (and, possibly,
recirculated) by being drawn back into the device by means of the reduced pressure.
This arrangement also has the advantage of reducing the tendency of the gas delivered
from the device to diffuse away from its surface and into its surroundings.
[0020] Preferred embodiments of the invention will now be described, by way of example only,
with reference to the accompanying drawings wherein:
Figure 1 shows a perspective view of a device according to one embodiment of the invention;
Figure 2 shows a perspective view of a cross-section through a device according to
another embodiment of the invention;
Figure 3 is a plan view of the device shown in Figure 2;
Figure 4 is a perspective view of a cross-section through a device according to yet
another embodiment of the invention; and
Figure 5 is a perspective view of a cross-section through a device according to a
further embodiment of the invention.
[0021] Referring to Figure 1, device 1 has a main body 2 which is attached to gas inlet
3. Gas inlet 3 allows gas to be passed into the interior of main body 2. Main body
2 comprises an upper sheet 4 and a lower sheet (not shown) of woven, knitted or non-woven
fibres. Upper sheet 4 and the lower sheet are joined at their edges by four side walls
5 (only two of which are shown), and, optionally, internally by monofilaments, which
may be made from the same material (or a different material) from the upper sheet
4 and the lower sheet. Side walls 5 can be made impermeable by, for example, heat
fusing or applying an impermeable film of a polymer or a sealant. In use, gas is passed
into main body 2 through inlet 3 to inflate the main body. The term inflation, as
used throughout the specification, means that main body 2 of device 1 is reversibly
(and generally outwardly) deformed by the pressure of the gas within main body 2 such
that the pressure of the gas within main body 2 is higher than the pressure outside
main body 2. Gas permeates through upper sheet 4, and also from the lower sheet if
this too is gas permeable (although it need not be), and reaches a steady state when
the gas permeates out of main body 4 at the same rate at which it is added via inlet
3. Device 1 permits the delivery of gas in a direction away from upper sheet 4 (and
also from the lower sheet if it is gas permeable) in substantially only a single direction
allowing it to be directed towards an article or region in the vicinity of device
1. Maintaining the sheets substantially planar and parallel, using monofilaments,
further restricts the flow of gas to a single direction.
[0022] In Figure 2, device 6 has an upper sheet 7 and a lower sheet 8. Upper sheet 7 and
lower sheet 8 are joined at regions 9, for example, either by adhesion of sheets 7
and 8 or by sheets 7 and 8 being heat sealed, woven, knitted or stitched together.
In the regions 10 where the sheets are unjoined, gas pressure within device 6 (supplied
from a gas inlet which is not shown) inflates regions 10 to give them a tubular shape.
Gas permeates out of upper sheet 7. In this embodiment, lower sheet 8 is made substantially
impermeable by a coating 11 (for example, of a polymeric substance) which is applied
thereto such as by adhesion using a suitable adhesive. Thus, the gas permeates substantially
only out of upper sheet 7.
[0023] Figure 3 shows device 6 of Figure 2 to illustrate how gas is directed to regions
10. An inlet 12 for gas comprises a hollow tube in the form of a manifold, which may
be rigid or deformable, and which has an opening 13 through which the gas is directed.
Regions 10 and inlet 12 have common openings 15 which allow the passage of gas from
inlet 12 into the regions 10.
[0024] A variant of device 6 shown in Figures 2 and 3 is illustrated in Figure 4. In this
embodiment of the invention, alternate regions 10 contain supports 14. Supports 14
are of resiliently deformable material (such as foamed rubber) and provide support
for an article placed on device 6; this is particularly important when a heavy article
is placed on device 6 since the gas pressure may be insufficient to allow regions
10 to support the article and, without supports 14, regions 10 may collapse under
the weight of the article.
[0025] Another variant of the device 6 of Figures 2 and 3 is shown in Figure 5. In this
embodiment, the device 6 resembles that of Figure 4 with supports 16 in alternate
regions 10 of device 6. However, supports 16 are porous (being made, for example,
of open cell foam) and have hollow centres 17 through which insert tubes 18 pass.
Insert tubes 18 are perforated along their length, although this is not shown in the
Figure. Insert tubes 18 may be connected to a source of reduced pressure by means
which are not shown. The reduced pressure causes gas to flow through upper sheet 7
and support 16 and into insert tube 18 by way of the perforations in insert tube 18.
This flow of gas into the device 6 occurs throughout the length of the upper sheet
7 which is adjacent to supports 16. Thus, at least a proportion of the gas emitted
from regions 10 is recovered and may be recirculated, allowing a reduction in the
overall cost of the process. This arrangement has the further advantage that the gas
delivered from device 6 flows out from regions 10 and back into insert tubes 18 setting
up a pattern of gas flow which reduces the tendency of the gas to diffuse away from
the immediate vicinity of device 6.
[0026] The following non-limiting example illustrates, by way of example only, the construction
of a device according to the invention.
EXAMPLE 1
[0027] A 436 g/m
2 plain weave double layer woven fabric of nylon fibres in continuous filament yarns
was produced as a 25cm x 25cm sheet with a solid woven section of 5cm width joining
the sides of each layer.
[0028] A coating of a soft aliphatic polyurethane dispersion of viscosity 6,960 mPas (6,960
cps) was applied to one of the layers. The coated fabric was dried and cured at 160°C.
The resulting coated surface had a porosity of about 10 dm
3/m
2/s.
[0029] The uncoated layer was then made impermeable. An impermeable film of polyurethane
of 72 g/m
2 weight and a gauge of 50µm was coated with a soft polyurethane adhesive paste of
viscosity 57,600 mPas using an annular grooved rod (knife over air system) or by knife
over roller to give a coating of adhesive at a level of about 20 g/m
2. The uncoated layer was then brought into contact with the adhesive-coated face of
the polyurethane film whilst the adhesive was still wet and subjected to heat to form
a bond between the layer and the film. The double layer of fabric was then sealed
around three of its sides by heat fusing the edges or by applying a silicone sealant.
A flexible air supply tube was then inserted into one edge of the double layer and
sealed to the fabric using a silicone sealant.
[0030] Compressed, refrigerated air was pumped into the device at a pressure of 200 Pa (DIN
53887-200cm
2 test area) to inflate it. A fine dispersion of chilled air issued from the porous
face of the fabric at a rate of about 10 dm
3/m
2/s. Food items placed directly above the porous face of the fabric were chilled without
a significant reduction in the temperature of the working environment. Maintaining
food items at a low temperature in this way also greatly reduced the tendency for
water to condense on the food from the surrounding warm air.
1. Gas delivery device (1;6) comprising an inlet (3;12) for gas and two sheets (4;7,8)
of woven, knitted or non-woven fibres arranged as a double layer, one sheet (7) having
a portion which is gas permeable and the sheets being joined such that at least a
part of the region (2; 1 0) between the sheets is capable of being inflated by gas
directed through the inlet (3;12) and, when inflated, of allowing the gas to permeate
out of the device through the gas permeable sheet (4;7), characterised in that the other sheet (8) is substantially gas impermeable.
2. Device as claimed in claim 1, wherein at least one of the sheets (4;7,8) is resiliently
deformable.
3. Device as claimed in either claim 1 or claim 2, wherein the sheets (4;7,8) comprise
a fabric of woven fibres.
4. Device as claimed in any one of the preceding claims, wherein the permeability of
the sheet (4;7) which is at least partly gas permeable is reduced by coating with
a polymer dispersion.
5. Device as claimed in any one of the preceding claims, wherein the two sheets (4;7,8)
are woven as one fabric.
6. Device as claimed in any one of the preceding claims, wherein the sheets (7,8) comprise
joined regions (9) at which the sheets are joined and unconnected regions (10) which
are capable of being inflated by a gas.
7. Device as claimed in claim 6, wherein the joined (9) and unconnected regions (10)
are arranged as regularly spaced bands along the double layer.
8. Device as claimed in claim 7, wherein a proportion of the unconnected regions (10)
contain substantially rigid material.
9. Device as claimed in claim 7, wherein a proportion of the unconnected regions (10)
comprise a substantially rigid porous tube (18), the interior of the tube being capable
of connection to gas of reduced pressure.
10. Method of delivering gas comprising providing the gas from a device according to any
one of claims 1 to 9.
11. Method as claimed in claim 10, wherein the gas is of a predetermined temperature such
that it regulates the temperature of its surroundings.
12. Method as claimed in claim 10, wherein the gas is at a temperature below room temperature.
13. Method as claimed in claim 12, wherein the gas is delivered to a comestible product.
1. Gasabgabevorrichtung (1;6), umfassend einen Einlass (3;12) für Gas und zwei als Doppelschicht
angeordnete Lagen (4;7,8) von gewebten, gewirkten oder Vlies-Fasern, wobei eine Lage
(7) einen Teil aufweist, der gasdurchlässig ist, und die Lagen so miteinander verbunden
sind, dass sich mindestens ein Teil des Bereichs (2;10) zwischen den Lagen mittels
Gas aufblasen lässt, das durch den Einlass (3;12) gelenkt wird, und es in aufgeblasenem
Zustand dem Gas erlauben kann, durch die gasdurchlässige Lage (4;7) aus der Vorrichtung
heraus zu dringen, dadurch gekennzeichnet, dass die andere Lage (8) im Wesentlichen gasundurchlässig ist.
2. Vorrichtung nach Anspruch 1, bei der mindestens eine der Lagen (4;7,8) elastisch verformbar
ist.
3. Vorrichtung nach Anspruch 1 oder Anspruch 2, bei der die Lagen (4;7,8) ein Textilerzeugnis
aus gewebten Fasern umfassen.
4. Vorrichtung nach einem der vorangehenden Ansprüche, bei der die Durchlässigkeit der
Lage (4;7), die mindestens teilweise gasdurchlässig ist, durch Beschichtung mit einer
Polymerdispersion vermindert ist.
5. Vorrichtung nach einem der vorangehenden Ansprüche, bei der die zwei Lagen (4;7,8)
als ein Textilerzeugnis gewebt sind.
6. Vorrichtung nach einem der vorangehenden Ansprüche, bei der die Lagen (7,8) miteinander
verbundene Bereiche (9) umfassen, an denen die Lagen miteinander verbunden sind, und
unverbundene Bereiche (10), die sich mittels eines Gases aufblasen lassen.
7. Vorrichtung nach Anspruch 6, bei der die miteinander verbundenen (9) und die unverbundenen
Bereiche (10) als in regelmäßigen Abständen angeordnete streifen entlang der Doppelschicht
angeordnet sind.
8. Vorrichtung nach Anspruch 7, bei der ein Anteil der unverbundenen Bereiche (10) im
Wesentlichen starres Material enthält.
9. Vorrichtung nach Anspruch 7, bei der ein Anteil der unverbundenen Bereiche (10) eine
im Wesentlichen starre poröse Röhre (18) umfasst, wobei sich das Innere der Röhre
an Gas mit Unterdruck anschließen lässt.
10. Verfahren zum Abgeben von Gas, umfassend Bereitstellen des Gases aus einer Vorrichtung
nach einem der Ansprüche 1 bis 9.
11. Verfahren nach Anspruch 10, bei dem das Gas von einer vorbestimmten Temperatur ist,
so dass es die Temperatur seiner Umgebung reguliert.
12. Verfahren nach Anspruch 10, bei dem sich das Gas auf einer Temperatur unterhalb von
Raumtemperatur befindet.
13. Verfahren nach Anspruch 12, bei dem das Gas zu einem essbaren Produkt abgegeben wird.
1. Dispositif de délivrance de gaz (1 ; 6) comprenant une entrée (3 ; 12) pour un gaz
et deux feuilles (4 ; 7 ; 8) de fibres tissées, tricotées ou non tissées agencées
sous forme d'une double couche, une feuille (7) ayant une partie qui est perméable
aux gaz et les feuilles étant jointes de telle sorte qu'au moins une partie de la
région (2 ; 10) entre les feuilles est capable d'être gonflée par un gaz dirigé à
travers l'entrée (3 ; 12) et, lorsqu'elle est gonflée, de permettre au gaz de sortir
du dispositif à travers la feuille perméable aux gaz (4 ; 7), caractérisé en ce l'autre
feuille (8) est sensiblement imperméable aux gaz.
2. Dispositif selon la revendication 1, dans lequel au moins l'une des feuilles (4 ;
7 ; 8) est déformable de façon résiliente.
3. Dispositif selon la revendication 1 ou la revendication 2, dans lequel les feuilles
(4 ; 7 ; 8) comprennent un tissu de fibres tissées.
4. Dispositif selon l'une quelconque des revendications précédentes, dans lequel la perméabilité
de la feuille (4 ; 7) qui est au moins partiellement perméable aux gaz est réduite
par revêtement avec une dispersion de polymère.
5. Dispositif selon l'une quelconque des revendications précédentes, dans lequel les
deux feuilles (4 ; 7 ; 8) sont tissées comme un tissu.
6. Dispositif selon l'une quelconque des revendications précédentes, dans lequel les
feuilles (7, 8) comprennent des régions jointes (9) au niveau desquelles les feuilles
sont jointes et des régions non reliées (10) qui sont capables d'être gonflées par
un gaz.
7. Dispositif selon la revendication 6, dans lequel les régions jointes (8) et non reliées
(10) sont agencées sous forme de bandes régulièrement espacées le long de la double
couche.
8. Dispositif selon la revendication 7, dans lequel une proportion des régions non reliées
(10) contient une matière sensiblement rigide.
9. Dispositif selon la revendication 7, dans lequel une proportion des régions non reliées
(10) comprend un tube poreux sensiblement rigide (18), l'intérieur du tube étant capable
d'un raccord à un gaz à pression réduite.
10. Procédé de délivrance d'un gaz comprenant la fourniture du gaz à partir d'un dispositif
selon l'une quelconque des revendications 1 à 9.
11. Procédé selon la revendication 10, dans lequel le gaz est à une température prédéterminée
de sorte qu'il régule la température de son environnement.
12. Procédé selon la revendication 10, dans lequel le gaz est à une température au-dessous
de la température ambiante.
13. Procédé selon la revendication 12, dans lequel le gaz est délivré à un produit comestible.