GB2522485A

GB2522485A - Dispensing apparatus and methods

Info

Publication number: GB2522485A
Application number: GB1405447.2A
Authority: GB
Inventors: Graham Plews; Simon Brereton
Original assignee: British American Tobacco Investments Ltd; British American Tobacco Co Ltd
Current assignee: British American Tobacco Investments Ltd
Priority date: 2014-03-26
Filing date: 2014-03-26
Publication date: 2015-07-29
Also published as: GB201405447D0

Abstract

An apparatus 1 is provided for dispensing a liquid in repeated dispensing operations. the apparatus comprising a nozzle 5 or aperture through which the liquid is dispensed from reservoir 2 through conduit 3. There are means comprising source 6, conduit 7 and switch 4 for purging the nozzle or aperture between dispensing operations. A method for dispensing a liquid is also provided, the method comprising dispensing the liquid via a nozzle or aperture, purging the nozzle or aperture to remove any residual liquid in the nozzle or aperture, and dispensing the liquid again. The liquid may be a phase change material (PCM) and the purging fluid may be air. The purging fluid may be heated.

Description

Dispensing apparatus and methods

Technical Field

The present invention relates to apparatus and methods for dispensing liquids. More specifically, the invention relates to apparatus for dispensing sensitive liquids, such as phase change materials, incorporating a mechanism for periodically purging a section of the apparatus so as to clear any residual liquid, in addition, the invention relates to methods for dispensing such liquids, incorporating an action or measure for periodically clearing any residual liquid from an apparatus for dispensing the liquid.

Background

Phase change materials (PCMs) are materials that are capable of absorbing or releasing energy -usually in the form of heat -upon changing phase. As a result, PCMs are capable of latent heat storage and they have a wide range of applications.

Some commonly used PCMs release heat upon crystallisation, as they go from liquid to solid form. It is often convenient, particularly at a larger scale, to handle such PCMs in their liquid phase. However, the phase change of a PCM from its liquid form to its solid form may be triggered by a number of conditions. For examp'e, a rapid change in temperature, physical impact and/or exposure of the material to a crystal of the same materia' may trigger such a phase change. Care must therefore be taken when handling PCMs to ensure that a phase change is not prematurely triggered. Specialist apparatus is thus required to handle such sensitive materials, particularly during complex manufacturing operations.

Summary of Invention

According to a first aspect of the invention, an apparatus is provided for dispensing a liquid in repeated dispensing operations, the apparatus comprising a nozzle or aperture through which the liquid is dispensed and a means for purging the nozzle or aperture between dispensing operations.

In some embodiments, the means for purging is configured to pass a fluid through the nozzle or aperture.

Tn some embodiments, the means for purging is configured to pass a fluid through the nozz'e or aperture tinder pressure.

In some embodiments, the fluid is pressurised gas, such as pressurised air.

Tn some embodiments, the fluid is heated.

In some embodiments, the means for purging is configured to purge the nozzle or aperture following each dispensing operation.

In some embodiments, the apparatus further comprises a reservoir in which the liquid o to be dispensed is stored prior to dispensing.

In some embodiments, the liquid to be dispensed is a phase change material.

In some embodiments, the apparatus comprises a switch to allow dispensing of the liquid or purging of the nozzle or aperture.

According to a second aspect of the invention, a method is provided for dispensing a liquid, the method comprising dispensing the liquid via a nozzle or aperture, purging the nozzle or aperture to remove any residual liquid in the nozzle or aperture, and dispensing the liquid again.

In some embodiments, the dispensing and purging steps are repeated but purging of the nozzle after every dispensing step is optional.

Brief Description of the Drawings

Embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure lisa schematic representation of an apparatus according to an embodiment of the invention; and Figure 2 is a sectiona' view of an apparatus according to a further embodiment.

Detailed Description

The present invention seeks to address issues associated with the dispensing of sensitive liquid materials such as PCMs and other liquid materia's, particularly those that are unstable (for exampk, are prone to phase change), for example those that are normally solid at room temperature, and/or those that are sensitive to contamination.

PCMs that release heat when changing from their liquid to solid phase are often very difficult to handle and prone to crystallisation. The crystallisation of liquid PCMs may be triggered by a variety of different conditions, including a change in temperature, especially a rapid drop in temperature, mechanical stresses, dehydration, and exposure to the same PCM in solid form. For this reason, some PCM dispensing apparatuses have been developed which have been specifically adapted in order to mitigate such crystallisation.

o For example, WO 2012/139013 disóloses an apparatus for handling and dispensing PCMs. The apparatus may be heated to temperatures of at least 200°C to prevent the liquid PCM from solidifying.

US 2011/290266 discloses an apparatus for handling and dispensing PCMs. In order to prevent unwanted crystaflisation of the PCM at any point within the apparatus, as well as heating the apparatus, it is stated that the atmosphere within the apparatus should be kept moist to avoid dehydration (and therefore crystaflisation) of the PCM.

Another approach which is sometimes used is to fill and seal the chamber, accepting that the PCM will solidify, and then heating the entire chamber to melt all of the crystals within it. This approach is not very efficient and is not appropriate in all circumstances as some chambers or devices may be damaged by heating.

Despite the measures mentioned above to prevent triggering of crystallisation of the PCM during dispensing, these apparatuses may still see unwanted crystallisation. It has now been discovered that a particular problem is associated with residual liquid PCM remaining in the dispensing apparatus. This residual liquid may be particularly prone to crystallisation and will be contacted by further liquid PCM being subsequently dispensed, thus triggering crystallisation of that PCM, with catastrophic consequences for the apparatus and the dispensing operation.

The present invention seeks to provide an apparatus and methods suitable for dispensing sensitive liquid materials such as PCMs. It is an object of at least some embodiments of the present invention to eliminate unwanted crystallisation or contamination of these sensitive liquids and thus provide reliable apparatuses and methods for rapidly and repeatedly dispensing the liquids.

Possible hydrated saks which may be used as PCMs in connection with the apparatuses and methods of the present invention include sodium acetate trihydrate (SAT), sodium hydroxide monohydrate, barium hydroxide octahydrate, magnesium nitrate hexahydrate and magnesium chloride hexahydrate.

Sodium acetate trihydrate (CH3COONa 3FL,O) is a PCM which emits heat when its supercooled liquid form crystallises. This material has been utilized in hand warmer devices and the like.

Tt is a common requirement for PCMs to be dispensed in predetermined doses, for examp'e, during the sequential filling of a number of receptades with a PCM. Tdeafly, when one receptacle is full, dispensing of the PCM is temporarily ceased and the full receptacle is replaced with an empty receptacle and the dispensing of the PCM is resumed, with this process being repeated.

Tn such scenarios the flow of PCM is essentially interrupted whilst the full receptacle is replaced. Although components of the apparatus used to handle PCMs may be heated in order to keep the PCM above its melting point and thus prevent its solidification, it can be difficult to uniformly heat the entire apparatus to suitable temperatures. In particular, any residual PCM situated at a nozzle or aperture from which the PCM exits the dispensing apparatus is particularly difficult to keep at a uniform temperature. It is speculated that this is at least in part due to the fact that the PCM is exposed to the air at this point, which can cause rapid cooling. What is more, this cooling may be exacerbated by the fact that the volumes of PCM in question tend to be small, with the surface area to volume ratio being high, which will accelerate cooling. The cooling is difficult to control and can trigger crystallisation.

Moreover, even if the residual PCM present in the nozzle or aperture of the apparatus remains in liquid form, the difference between the cooled temperature of this residual PCM and the warmer (heated) main PCM flow can provide sufficient "shock" to the PCM to trigger crystallisation, either within the apparatus or within the receptacle into which the PCM is being dispensed, neither of which is desirable.

Therefore, interruptions in the flow of PCM can be problematic because any residual PCM in the exit nozzle or aperture of the apparatus has an opportunity to cool and this can trigger (directly or indirectly) crystallisation of that residual PCM and, more importantly, of the main flow of PCM being dispensed.

Given the exposure of the residual PCM to the air and the small volumes involved, it can be extremely difficult to prevent cooling by, for example, heating the nozzle or aperture of the apparatus.

In light of these issues, the apparatuses and methods of at least some embodiments of the present invention seek to remove the residual PCM left by one dispensing operation Jo -that is following the dispensing of one dose of PCM or the filling of one receptacle -before commencing the next dispensing operation.

This remova' of the residual PCM reduces the risk of fresh liquid PCM (from the main flow) coming into contact with any PCM that may reside within the nozzle between dispensing operations.

Tt should be noted that it is often desirable for the apparatus to operate at high speeds in order to rapidly fill large numbers of receptacles. Therefore, the time between dispensing operations, and therefore the time available for removing residual PCM from the nozzle of the apparatus, may be extremely short. For example, it would be impractical for an operator to physically swab the inside of the nozzle in between dispensing operations.

There is therefore a need for apparatuses and methods that are capable of rapidly and reliably dispensing liquids in predetermined volumes to receptacles whilst also purging the nozzle or aperture of the apparatus of residual liquid between dispensing operations.

In some embodiments which may be particularly preferred, the purging is of the nozzle or aperture and associated conduits, but does not involve purging of a metering chamber or other parts of the apparatus.

An apparatus used to dispense liquids into receptacles will generally comprise a reservoir which holds the liquid to be dispensed, a conduit leading from the reservoir and allowing transfer of the liquid from the reservoir to a metering chamber in which a predetermined volume of liquid may be held. The predetermined volume of the liquid will be dispensed from the metering chamber into a waiting receptacle via a nozzle or aperture. Following the emptying of the metering chamber to dispense the predetermined volume of liquid, the metering chamber will be refilled with fresh liquid from the reservoir. Following the dispensing of the metered volume of liquid into a receptacle, some residual liquid may remain in the nozzle or at the aperture of the apparatus. Additionally or alternatively, some residual liquid maybe retained in the valve which switches the flow path between filling the metering chamber and dispensing the liquid.

jo Where such an apparatus is used to dispense a temperature-sensitive liquid such as a PCM, afl of the aforementioned parts of the apparatus may be heated. It is particulañy important for the reservoir to be heated, so that the liquid held therein (often for a prolonged period) can be kept at or above a suitable temperature. For examp'e, for a PCM, it would be advantageous to keep the temperature above its melting point, to prevent unwanted phase change.

Tn the apparatuses according to at least some of the embodiments of the invention, the apparatus is provided with a means for removing residual liquid from the nozzle or aperture.

In embodiments, the means for purging the nozzle or aperture of residual liquid comprises passing fluid through the nozzle or aperture so as to remove any residual liquid. In some embodiments, the means for purging the nozzle or aperture is also capable of removing residual liquid which has subsequently solidified.

In some embodiments, the fluid is forced through the nozzle or aperture to remove the residual liquid. The fluid may be fast-flowing and/or pressurised. The fluid may be any fluid suitable for such a purpose and it maybe specifically selected in light of the physical and/or chemical nature of the residual liquid to be purged.

In some embodiments, the fluid used to purge the nozzle or aperture is any suitable gas.

In some embodiments, the fluid may be pressurised air. In other embodiments, the fluid may be an inert gas.

Compressed air may be used, but other gases might be useful in some applications. In some embodiments, the pressure is in the range of 1-10 bar. The appropriate purge time will depend on the geometry of the apparatus, bnt in some embodiments it will be less than a second.

Tn some embodiments of the invention, the fluid used to pnrge the nozzle or aperture is any suitable liquid, in some embodiments, the liquid may be water.

In some embodiments, the purge could involve the use of two fluids, either sequentially or simultaneously. In one particular embodiment, the purge involves a solvent followed by air.

Tn some embodiments, the purge may be used to dilute the metered dose of PCM in the receptacle, in order to achieve a desired concentration of PCM in the receptacle. For example, in one embodiment, a volume of a concentrated liquid PCM maybe dispensed into a receptacle, followed by a predetermined volume of solvent, for example, a timed flow of the solvent.

Tn some embodiments of the invention, the fluid used to purge the nozzle or aperture may be at ambient or room temperature. In other embodiments, the fluid may be heated. For example, where the residual liqu d to be removed is a PCM, the fluid may be heated to a temperature at or above the melting point of the PCM. Additionally or alternatively, the fluid may be used at a temperature suitable for facilitating the removal of the residual liquid. This may involve heated fluid reducing the adhesion of the residual liquid to the apparatus. Such embodiments may be particularly advantageous where the purging is removing residual liquid that has already solidified.

Figure 1 is a schematic illustration of an example of a simple dispensing apparatus 1 according to some embodiments of the invention. The liquid to be dispensed, for example a PCM, is stored in a reservoir 2 and is transferred to a receptacle 8 through a conduit 3 to a switch 4 and, when the switch 4 is in a first position, throLigh the switch 4 to a nozzle 5 and into a waiting receptacle 8. Purging fluid, such as pressurised air, is provided from a source 6 and is transferred through a conduit 7 to the switch 4. When the switch 4 is in a second position, the pressurised air passes through the switch 4 and through the nozzles, removing any residual liquid in the nozzle.

In some embodiments, the switch 4 may only allow for the passage of either the liquid to be dispensed or the purging fluid through nozzle 5 at any one time. The switch 4 is a convenient way to ensure that the purging fluid does not flow throngh the nozzle 5 at the same time as the liquid being dispensed. Such an event would be highly undesirable as it would likely result in the liquid entering the receptacle too fast, and at least some fiquid may not enter the receptacle. Tt could also potentiaflytrigger crystallisation.

In some embodiments, the volume of liquid to be dispensed into a receptacle is controlled by the switch 4 and, more specifically, by the timing of the movement of the switch 4 from its first to its second position. Alternatively, the volume of liquid to be jo dispensed is controlled by a metering chamber (not shown) into which a predetermined volume of liquid is filled before being dispensed, optionally via a switch such as the one illustrated in Figure 1. Tn such an arrangement, the metering chamber could be positioned between the reservoir 2 and the switch 4.

Tn other embodiments, the switch 4 could incorporate a metering chamber, the switch mechanism allowing either the liquid to be dispensed from the chamber or the purging fluid to pass though the nozzle.

An alternative apparatus is shown in Figure 2. The apparatus 11 comprises a housing 12 surrounding a metering chamber 13 and head 14. The head 14 comprises a switch 15 and a nozzle 19. Inlets in the head 14 connect the switch 15 selectively to the metering chamber 13, or a supply of pressurised air (not shown) and to the nozzle. In some embodiments, a supply of the liquid to be dispensed (not shown) is also directly connected to the switch 15 via an inlet in the head 14. Alternatively, the head connects the supply of the liquid to be dispensed to the metering chamber, via a valve or other control means (not shown).

The liquid to be dispensed is fed into the metering chamber 13 from a reservoir (not shown). The metering chamber 13 includes a plunger 17 which is moveable within the chamber 13 to change the volume of the metering chamber 13. When the plunger 17 is in a retracted position, the metering chamber 13 has a predetermined volume and may be filled with the liquid to be dispensed.

When the metering chamber is full and the apparatus is ready to dispense the metered volume of liquid, the switch 15 is moved to a position so that a channel 16 in the switch connects the metering chamber 13 and nozzle 19. When the switch 15 aligns the channel 16 with the metering chamber 13, the plunger 17 is moved into an extended position, thereby reducing the volume of the metering chamber 13 and forcing the liquid out of the chamber 13 and into the head 14 of the device.

The plunger 17 may be operated by any suitable means. in some embodiments, the plunger may be operated pneumatically or hydraulically. In some embodiments, the plunger 17 maybe moved under pneumatic pressure. In some embodiments, the apparatus includes a sensor (not shown) to detect the position of the plunger 17. This sensor may, in some embodiments, detect when the plunger 17 reaches the fully Jo extended position and this may trigger both retraction of the plunger 17 to its retracted position and rotation of the switch 15 to dose the connection between the metering chamber 13 and the nozzle 19.

In some embodiments, the liquid to be dispensed may be fed into the metering chamber 13 under pressure. Tn other embodiments, the retraction of the plunger 17 may create a vacuum which draws the liquid into the metering chamber. Tn such embodiments, it is necessary for the metering chamber 13 to be in fluid connection with the reservoir holding the liquid to be dispensed when the plunger 17 is retracted. In some embodiments, this may be achieved by a valve between the metering chamber and the reservoir (not shown). In some embodiments, the inlet through which the liquid enters the metering chamber 13 from the reservoir is in the head 14 of the apparatus. In some embodiments, the opening and closing of this liquid inlet is controlled by the switch 15.

The inlet may be open to allow liquid to be dispensed to enter the metering chamber from the reservoir when the switch 15 is in the position in which it also connects the air supply to the nozzle 19 for the purging of the nozzle 19. Such an embodiment would allow the purging of the nozzle 19 to occur at the same time as the filling of the metering chamber 13 with the next dose of liquid. This would require the switch 15 to have at least two channels. Alternatively, the switch 15 could have a third position in which it connects the liquid reservoir and the metering chamber 13 so that the purging step and the filling step happen sequentially, rather than simultaneously.

Thus, in some embodiments, the switch controls the flow of the liquid to be dispensed and the purging means, such as pressurised air, through the apparatus. The switch may be positioned to only allow the metered volume of liquid to pass through the nozzle and -10-into the waiting receptacle. Alternatively, the switch may be positioned to allow the purging means to pass through nozzle. In some embodiments, the switch may also be positioned to allow the liquid to be dispensed to flow from the reservoir into the metering chamber. Tn some embodiments, the switch may be configured with at least two channels, to allow the purging step and filling of the metering chamber to happen at the same time.

In the illustrated embodiment, the switch 5 has a single channel 6. In a first position, (position A) the channel 16 of the switch 15 connects the metering chamber 13 and the Jo supply of liquid to be dispensed, for the filling step. Tn a further position (position B), the channel 16 of the switch 15 connects the metering chamber 13 and nozzle 19, for the dispensing step. Tn a yet further position (position C), the channel 6 of the switch 1 connects the supply of pressurised air and the nozzle 19, for the purging step. The switch 15 may rotate or otherwise move between positions. The switch 15 may have one or morechannels in ordertoprovidethedesiredconnections.

Tn the embodiment iflustrated in Figure 2, the switch i is positioned in the head 14 of the apparatus. The switch 15 may be operated by being rotated within the head 14, for example about its central axis of rotation. The rotation moves the switch between specific, predetermined positions. The switch may be operated by any suitable means such as electrical, pneumatic or hydraulic means.

In some embodiments, the nozzle of the apparatus is configured to allow the liquid to be dispensed into a receptacle in a smooth and accurate manner. In some embodiments, the nozzle may be shaped to minimise drips, spillage and/or retention of residual liquid. In some embodiments, the nozzle may be replaceable.

In some embodiments, the apparatus may comprise a plurality of nozzles or apertures for dispensing the liquid. In such embodiments, the nozzles or apertures may synchronously or asynchronously dispense the liquid. In such embodiments, the nozzles or apertures may also be synchronously or asynchronously purged of residual liquid.

In some embodiments, the nozzle or aperture is only to be purged between liquid dispensing operations. The frequency of purging the nozzle or aperture may vary. For example, the nozzle or aperture may be purged whenever it is construed necessary to -11 -remove residual PCM from the nozzle. In some embodiments, the nozzle is purged after every dispensing operation. In other embodiments, a sensor maybe provided to detect when purging is required, for example by detecting the presence of residual liquid in the nozzle or at the aperture.

In some embodiments, it is desirable to maintain the liquid to be dispensed at an elevated temperature. In particular, it maybe desirable to ensure that the liquid is not exposed to any rapid drop in temperature. To those ends, in some embodiments at least parts of the apparatus maybe heated. In some embodiments, at east parts of the o apparatus are insulated. For example, where the reservoir of Uquid to be dispensed forms part of the apparatus, this is heated, preferably to maintain the liquid at a temperature at or above its melting point. Tn some embodiments, the conduits between parts of the apparatus are heated and/or insulated. Tn some embodiments, the metering chamber is heated and/or insulated. In some embodiments, the head 14 and/or switch of the apparatus are heated and/or insulated. Tn some embodiments, the nozz'e is heated and/or insulated. In some embodiments, the apparatus may be heated using cartridge heaters.

In some embodiments, the purging means is heated to above ambient temperature. For example, in some embodiments, the purging means is heated pressurised air or water.

In some embodiments, the liquid material to be dispensed is a PCM. In an embodiment, the liquid material is sodium acetate trihydrate (SAT).

Example

The following is an illustrative example of an embodiment of the invention, with reference to the apparatus of Figure 2. The liquid to be dispensed is SAT. The apparatus switch 15 is in a position (identified as switch position A) such that the reservoir holding the SAT and the metering chamber 13 are connected. The plunger 17 is retracted within the metering chamber 13, which causes SAT to be drawn from the reservoir into the metering chamber 13, through a passage in the switch 15. The reservoir is heated to keep the stored SAT at a temperature of about 80°C.

When the plunger 17 has retracted to give the metering chamber 13 its desired, predetermined capacity, the filling of the metering chamber 13 stops. The switch 15 rotates about its central axis of rotation until the channel 16 connects the metering -12 -chamber with the nozzle 19 (identified as switch position B). Plunger 17 is then extended and moves longitudinally within the metering chamber 13, displacing the SAT contained therein through the switch 15 and through the nozzle 19, ont of the apparatus ii and into a waiting receptacle.

When the plunger 17 reaches its fully extended position (indicating that all of the SAT has been forced out of the metering chamber 13), the switch 15 rotates to a position (identified as switch position C) that connects the source of pressurised air with the nozzle 19. Pressurised air is then forced through the nozzle 19, expelling any residual Jo SAT from the nozzle or from the channel 16 within the switch 15. The switch 15 then rotates back to switch position A. Tn order to address various issues and advance the art, the entirety of this disclosure shows by way of illustration various embodiments in which the claimed invention(s) may be practiced and provide for superior apparatuses and methods for dispensing liquids. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and teach the claimed features. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope and/or spirit of the disclosure. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. In addition, the disclosure includes other inventions not presently claimed, but which may be claimed in future.

Claims

-13 -Claims 1. An apparatus for dispensing a liquid in repeated dispensing operations, the apparatus comprising a nozzle or aperture through which the liquid is dispensed and a means for purging the nozzle or aperture between dispensing operations.
2. An apparatus according to in claim 1, wherein the means for purging is configured to pass a fluid through the nozzle or aperture.
3. An apparatus according to claim 2, wherein the means for purging is configured to pass a fluid through the nozzle or aperture under pressure.
4. An apparatus according to claim 2 or 3, wherein the fluid is pressurised gas.
5. An apparatus according to any one of claims 2 to 4, wherein the fluid is heated.
6. An apparatus according to any one of the preceding claims, wherein the means for purging is configured to purge the nozzle or aperture following each dispensing operation.
7. An apparatus according to any one of the preceding claims, wherein the apparatus further comprises a reservoir in which the liquid to be dispensed is stored prior to dispensing.
8. An apparatus according to any one of the preceding claims, wherein the liquid to be dispensed is a phase change material.
9. An apparatus according to any one of the preceding claims, comprising a switch to allow dispcnsing of thc liquid or purging of the nozzle or apcrturc.
10. A method for dispensing a liquid, the method comprising dispensing the liquid via a nozzle or aperture, purging the nozzle or aperture to remove any residual liquid in the nozzle or aperture, and dispensing the fiquid again.

ii. A method according to claim 10, wherein the dispensing and purging steps are repeated but purging of the nozzle after every dispensing step is optional.