ADDITIVE PREPARATION APPARATUS

This invention relates to apparatus for preparing an additive, particularly apparatus suitable for melting an additive for application to a cigarette during manufacture thereof and to a method of preparing such an additive.

BACKGROUND

Many brands of cigarette contain a flavour which is applied during manufacture. Sometimes flavour is applied in the manufacturing plant 'primary' where it is mixed with the raw tobacco in large volumes as the tobacco is processed and prepared for 'secondary' processes. Secondary processes involve separating the tobacco and loading accurate quantities onto paper which is then rolled to form the cigarette tobacco rod, which is cut to length as appropriate. Other secondary processes involve manufacture of filter rods which are then combined with cigarette tobacco rods to form the cigarette. Sometimes flavour is applied in the secondary process into the tobacco stream as the cigarette tobacco rod is formed, onto the paper just before the cigarette rod is formed, or onto the filter 'tow' as the filter rod is formed. Sometimes it is even applied to packaging.

One of the key flavouring substances used in cigarette manufacturing is menthol, which is crystalline at room temperature and which melts at around 40 ⁰ C. Since liquid can be more conveniently applied than crystals or powder, the menthol crystals are usually melted into a liquid state by flavour application apparatus before being delivered to the point of application.

The temperature at which flavours are processed can affect the taste of the end product and, therefore, heated flavours are typically temperature controlled within a few degrees Celsius above melt temperature. This limits any scope to reduce melt times by running at higher temperatures and consequent higher input energy levels.

Although the description below mainly discusses menthol, the concepts apply to any flavour or other additive which needs to be heated, regardless of its state at room temperature. For example, other flavours may naturally reside in a liquid state at room temperature but may need to be heated in order to evaporate carrier fluids or to promote

volatility and dispersion when the flavour reaches the cigarette within the manufacturing process. Other flavours include mint, fruit, clove and vanilla. Other types of additives include dyes, glues, plasticisers or other fluids.

A known flavour application apparatus is the applicant's UFA1000 Universal Flavour Applicator which is illustrated in Figures 1 and 2.

The flavour application apparatus has a portable body 1 , mounted for example on castors 2. The body contains two generally cylindrical tanks 3A, 3B, each of which can be lifted out of the body as illustrated in Figure 2, by means of gripping handles 4A, 4B.

The tanks 3A, 3B each have a capacity of approximately 7.5 litres and contain the liquid flavour (or other additive) that is to be prepared for delivery. Flavour can be delivered from an output (not illustrated) in the apparatus 1 to a variety of locations (e.g. onto the cigarette paper, into the tobacco stream, into the tow), depending on requirements.

Solid menthol crystals are loaded into the tanks 3A ₁ 3B, each of which has a heated jacket (not illustrated) so that, through thermal conduction and convection, the crystals gradually melt into a liquid state. Although menthol does not require much energy to melt, it does not conduct heat particularly well. This leads to lengthy preparation times (in the order of a number of hours) before the tank of flavour is actually ready to use in the manufacturing process. It is not possible to simply increase the power to the heating element to speed up heating, as that would result in the crystals at the periphery of the tank being overheated leading to a loss or impairment of the flavour. In any case, such an increase in heating power would be unlikely to have a proportionate reduction in melting time, given the poor conductive properties of the menthol. Twin tank systems, such as the UFA1000, have the advantage of allowing liquid flavour to be delivered from one tank (3A) while, at the same time, the next tank of flavour (3B) is heating up so as to minimise or eliminate delay when the first tank is exhausted.

However, even with a twin tank system, the preparation time for each tank is significant because of the inefficient way in which menthol heats up. Poor conduction and convection means that there is a tendency for a liquid "pool" to form at the periphery and underside of the tank, around a central solid plug of menthol. If one tank is exhausted before the additive in the second tank has had sufficient time to melt, this can cause down time on the whole manufacturing apparatus until the second tank is ready.

A further problem is that, once melted, the liquid flavour may not be homogenously mixed if it contains components having different specific gravities.

These problems can be alleviated by the provision of a stirring system or agitator, such as that illustrated in Figure 3. The stirrer 5 is placed in one of the tanks 3A, 3B and is agitated automatically, e.g. by rotation as indicated by the arrow in Figure 3. The stirrer is of benefit in reducing the melt time but is obtrusive and increases the difficulty of cleaning the apparatus. Cleaning is particularly important where different additives or flavours are delivered from the same apparatus.

Furthermore, the stirrer 5 cannot easily be inserted into the tank when it contains solid crystals of menthol and is even more difficult to insert or remove from a tank which contains menthol that has been melted and re-solidified into a solid mass.

BRIEF SUMMARY OF THE DISCLOSURE

According to a first aspect of the invention, there is provided additive preparation apparatus, for preparing an additive to be applied to cigarette or filter during the manufacture thereof, the apparatus comprising: a tank suitable for receiving an additive; a heating chamber having walls defining an internal volume of smaller internal volume than said tank and in communication therewith; and a heating element associated with said heating chamber and for heating the contents thereof; characterised in that a pump is provided for recirculating additive from said heating chamber into said tank.

Thus, in use, additive from said tank enters said heating chamber where it is heated by said heating element and at least partially is recirculated back to the tank where it releases heat to additive in the tank.

Preferably, said additive is a flavour, preferably menthol crystals.

In a preferred form, said tank includes a heating element for example a heated jacket. Indeed, where the additive is solid, initial melting of the additive may transport additive

from the tank to the heating chamber, whereupon further heat is added to the additive before it is recirculated back to the tank accelerating melting of the additive in the tank. The acceleration may simply be by virtue of the heat added by the heating chamber being given up in the tank, but also it may be by virtue of the agitation caused by the pump, or by improved thermal linkage between the heated jacket and solid crystals in the tank.

The recirculating pump may comprise a reciprocating piston. Ideally, said recirculated additive is directed to a potentially cooler part of said tank.

Preferably, the apparatus further comprises a pump for delivering liquid additive from said heating chamber to a point of application. However, the apparatus may simply be one for preparing a tank of liquid additive, ready for transfer to an application machine.

In a preferred embodiment, said tank includes a gate or valve means, which may be automatically controlled, for selectively allowing passage of additive between said tank and said heating chamber. Said gate or valve means may be actuated to open by connection of said tank to the heating chamber, and to close by disconnection of the tank from the heating means.

Advantageously, said additive in said heating chamber is heated to a temperature of at least 40 ⁰ C and/or is pressurised.

In a preferred form, a part of said tank in communication with said heating chamber is tapered or otherwise shaped to facilitate the passage of said additive from said tank to said heating chamber.

Alternatively, or in addition, a part of said heating chamber in communication with said tank is tapered or otherwise shaped to facilitate the passage of said additive from said tank to said heating chamber.

Preferably, said heating element associated with said heating chamber is located substantially within said heating chamber.

Said heating element associated with said heating chamber may be located within one or more walls of said heating chamber.

In a preferred form, a wall of said heating chamber is provided with a heat-conducting fin extending into said internal volume of said heating chamber. The heat-conducting fin may itself contain a heating element.

In one embodiment, said heating element associated with said heating chamber is located in said internal volume of the heating chamber and could be in the form of a coil.

In a further embodiment, said heating element associated with said heating chamber is located externally to said heating chamber, for example, wherein said heating element comprises a heating jacket substantially surrounding said heating chamber.

Preferably, said heating element comprises inductive or radiant heating means.

Alternatively, said heating element is heated by fossil fuels such as coal or natural gas or by a thermo-nuclear or exothermic chemical reaction.

Alternatively, said heating element comprises hot fluid transport.

According to a second aspect of the invention, there is provided additive preparation apparatus, for preparing an additive to be applied to cigarette or filter during the manufacture thereof, the apparatus comprising: a tank suitable for receiving an additive; a heating chamber having walls defining an internal volume of smaller internal volume than said tank and in communication therewith; and a heating element associated with said heating chamber and for heating the contents thereof, characterised in that there is no other source of heat in the apparatus for the additive in the tank than that provided by said heating chamber.

In one arrangement, said apparatus may be part of or directly supply additive application apparatus, in which event, the rate of melting of the additive must exceed the rate of application. In the case of solid crystals, all that is needed is a supply of crystals in the tank from time to time, and possibly additional heating of any conduit leading melted additive from said heating chamber to its point of application.

In another arrangement, said apparatus may supply a separate reserve tank, which is independently heated, or at least heat-loss controlled, to maintain the temperature of additive in the reserve tank at or near the temperature of application. When full of melted liquid, the reserve tank can be employed as may be desired.

In a third aspect of the present invention, cigarette manufacturing apparatus including additive preparation apparatus as described in any of the preceding paragraphs.

According to a fourth aspect of the invention, there is provided a method of preparing an additive comprising the steps of: providing additive preparation apparatus as described in any of the preceding paragraphs; placing unprepared additive into said tank; enabling additive from said tank to enter said heating chamber; actuating said heating element so as to heat the contents of said heating chamber.

Preferably, the method further comprises the step of delivering prepared additive from an outlet of said heating chamber to a point of application.

Preferably, the method further comprises the step of recirculating additive from said heating chamber to said main tank.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 (prior art) is a perspective view of a twin tank flavour application apparatus; Figure 2 (prior art) shows how the tanks can be removed from the apparatus of Figure 1 ;

Figure 3 (prior art) shows a stirrer, drawn to a larger scale, suitable for use in the Figure 1 apparatus;

Figure 4 (prior art) is a schematic cross section of part of a flavour application apparatus;

Figure 5 is a schematic cross section of part of a flavour application apparatus embodying the second aspect of the invention;

Figure 6 is a schematic cross section of a modified embodiment of the flavour application apparatus of Figure 5; Figure 7 is a schematic cross section of a fourth embodiment of the flavour application apparatus;

Figure 8 is a schematic cross section of a fifth embodiment of the flavour application apparatus;

Figure 9 shows an alternative embodiment of the Figure 6 apparatus, having a main tank with tapered bottom;

Figures 10A and 10B are front and side views respectively of an embodiment of the heating chamber, drawn to a larger scale;

Figures 11A and 11B are top and front views respectively of an embodiment of the heating chamber; Figure 12 is a top view of an alternative embodiment of the heating chamber;

Figure 13 is a side section through an embodiment as shown schematically in Figure 7

Figure 14 is a detail A from Figure 13; and

Figure 15 is a plan view of the recirculating pump of Figures 13 and 14.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Throughout this application, the term "tank" is not limiting and is intended to include any container suitable for holding an additive in solid or liquid form.

Although the following description refers to an additive comprising a flavour, for example menthol crystals, of the type used in the manufacture of cigarettes, filters or cigars, these terms are not limiting and the invention is applicable to the preparation of any substance that requires melting from a solid to a liquid state.

Figure 4 (prior art) shows schematically how menthol crystals 6 are located in tank 3 where they can be heated and melted. Heating is provided by a heating jacket 7, which substantially surrounds the generally cylindrical tank 3. The melted menthol 6 leaves the tank 3 through an outlet port 8 at the bottom thereof, from where it is pumped through a conduit 9 to the point of application P.

Figure 5 shows an embodiment of the second aspect of the invention. Instead of a heating jacket, the tank 3 is provided with a heating chamber 10 at the bottom thereof. The heating chamber, containing a heating element, is of smaller volume than the main tank 3 and is fed with solid menthol crystals 6 from the main tank. The flavour crystals can be transferred into the heating chamber 10 either by gravity or an Archimedes screw or similar transport means from the main tank 3. Therefore, the main tank 3 can be described as "dry" since it only contains solid menthol crystals, which are not heated or melted.

The preparation of the additive, by heating and melting, occurs in the heating chamber 10, resulting in prepared additive 6A being in liquid form.

The volume of the heating chamber 10 may be selected according to the flow rate of prepared additive that is required. However, the volume of the heating chamber will always be less than the volume of the main tank 3. The shape of the heating chamber may be selected to optimise the efficiency of the heating element employed and to minimise the melt time for the additive in the heating chamber. For example, if the heating element is a longitudinal element internal to the heating chamber, the heating chamber itself may be generally cylindrical about the longitudinal axis of the heating element.

Figures 10A and 10B are front and cross-sectional side views respectively of a suitable heating chamber. The heating chamber is provided with a flared or tapered upper region 10A through which additive enters the heating chamber from the main tank. The additive 6A in the heating chamber is heated by means of heating elements embedded in the side walls 14, 15 of the heating chamber.

The surface area of the side walls 14, 15 is relatively high compared with the volume of additive 6A therein so as to maximise the surface area in contact with the additive 6A to increase the efficiency of heat transfer. In other words, the surface area of the side walls 14, 15 is much greater than the surface area of the end walls (not illustrated). It is desirable to minimise the distance between the heating element and the most distant region of additive 6A (e.g. the central region of the heating chamber).

An outlet 16 is provided near the bottom of the heating chamber for the exit of prepared additive 6A. The outlet may alternatively be sited on the underside of the base of the heating chamber.

In an alternative embodiment, heating is provided by a heating jacket substantially surrounding the walls of the heating chamber, instead of embedded heating elements therein. In a further embodiment, a heating element may be provided within the volume of additive 6A in the heating chamber.

Heating efficiency may be improved further by providing heat-conducting fins or the like within the heating chamber. For example, as illustrated in Figure 11A, fins 14A, 15A protrude or extend into the additive from the side walls 14, 15 in order to increase the available surface area. Optionally, the fins may contain heating elements, otherwise their function is to improve conduction of heat from the side walls into the additive 6A.

A top view of an alternative heating chamber is shown in Figure 12. This heating chamber has an internal heating plate or foil 16 in the form of a coil, again so as to maximise the surface area in contact with the additive 6A. A heating chamber of this type may be generally cylindrical or polygonal, for example, octagonal as shown in Figure 12.

Referring once again to Figure 5, once the flavour/additive 6A in the small heating chamber 10 has reached the correct processing temperature and has melted, it can then be transported using pump 11 into conduit 9 and then on to the point of flavour application P, for example onto the cigarette or filter making machine (not illustrated). Since the volume of additive to be heated in the heating chamber 10 is significantly smaller than volume of the main tank 3, the energy required to melt the additive is dramatically less than that required to heat and completely melt the contents of the main tank and keep it in a liquid state. Additionally, the time taken to reach the point where a sufficient volume of additive is available to be applied to the cigarette is dramatically reduced. Furthermore, since flavour additives are typically more volatile in their liquid state, minimising the quantity of heated additive at any one time reduces local environmental contamination and reduces any hazards associated with handling liquid flavours.

A controlled feed (instead of gravity feed) between the main tank 3 and the heating chamber 10 may be provided. This is shown schematically in Figure 6 as a "gate and feed system" 12 and may comprise a manually or automatically controlled gate or valve or the like.

In Figure 7 is illustrated apparatus emboding a first aspect of the present invention, in which some of the prepared additive 6A in the heating chamber 10 is re-circulated back into the main tank 3 by means of a reciprocating piston 13. This system is preferably used in conjunction with a conventional heating jacket 7 around the main tank, although the only heating element could be that located in the heating chamber 10.

Use of the reciprocating piston 13 promotes agitation of the additive in the main tank and also provides some heat to the main tank, with the aim of facilitating the melting of the dry crystals 6. Agitation allows movement of the additive to mix the hotter liquid additive 6A with the colder contents 6 of the main tank thereby heating the contents of the main tank. Mixing results in a more even temperature distribution in the main tank and improves the energy transfer from the heating elements to the additive whilst maintaining reasonable overall temperature levels within the main tank. To further reduce the time taken for the additive to reach the correct temperature, the output from the re-circulating system may be deliberately directed into the region furthest away from the heating element and/or towards regions with highest level of potential heat loss. Typically, the region furthest away from heating element would be in the centre of the main tank. Directed output from the heating chamber 10 may be squirted under pressure in order to promote agitation and circulation and also to provide forces and currents which break down any undesirable solid masses of additive or push any solid mass closer to the heating element.

Gate and feed system 12 can be used to direct the flow of the liquid additive. Until the additive reaches the correct temperature, gate 12 is closed so that all of the additive 6A in the heating chamber 10 is re-circulated into the main tank 3.

Once the correct operating temperature has been reached, the reciprocating piston 13 can be switched off, gate 12 can be opened and the pump 11 can operate to transport the liquid additive via conduit 9 to the point of application P. Alternatively, the reciprocating piston 13 can continue to operate in order to recirculate some of the liquid additive 6A back into the main tank.

In some circumstances it is desirable to have a stand-alone tank of additive for storage and/or preparation of liquid additive. For example, it may be desirable to have a tank of additive prepared away from the production line whilst the line is in operation, so that said prepared tank can be inserted into the line for immediate use when a previous tank has been exhausted. The stand-alone tank could be inserted into the line in the manner illustrated in Figure 2.

The invention includes a stand-alone tank as illustrated in Figure 8. The only difference between the stand-alone tank and that illustrated in Figure 7 is that the stand-alone tank does not have its own gate, pump and conduit for delivering additive. Instead, all of the additive in the heating chamber 10 is recirculated by piston 13 back into the main tank 3. The stand-alone tank may be insertable directly into flavour application apparatus in order to replace an exhausted tank.

It should be understood that, conveniently, the tank 3 is separable from the remainder of the equipment described above, for example with an automatically operating valve that closes when the tank is separated from the equipment, but which opens to communicate the tank with the heating chamber 10 when the tank is connected thereto. Indeed, this, in its simplest form is what the gate system 12 comprises.

Any of the above embodiments could be modified by providing a main tank as illustrated in Figure 9, wherein the lowermost region of the tank 3 is tapered or otherwise shaped to facilitate the passage of additive 6 from the main tank to the heating chamber 10. Similarly, the upper part of the heating chamber could be tapered or otherwise shaped as illustrated in Figure 10B to facilitate transfer of the additive from the tank to the heating chamber.

A practical embodiment of the first aspect of the present invention (as schematically illustrated in Figure 7) is shown in Figures 13, 14 and 15. Apparatus 1' has a base plate 1a to which is fixed socket 1b by plug 1c. Apparatus 1' has a heating jacket 7 that clamps around the tank 3 when the tank is inserted into the apparatus 1' and the apparatus is activated. The tank has a top lid 3a through which flavour crystals may be introduced into the tank 3 to replenish it. The tank has a bottom outlet 3b that is normally closed by a valve 12' including a valve member 3c. The valve member 3c is biased by a spring (not shown) towards a valve seat 3d to close the valve 12'. However,

on introduction of the tank 3 into the apparatus 1 ', and coupling of the tank outlet 3b with the socket 1b, a stop 1d of the socket presses the valve member 3c against the spring bias into the outlet 3b opening the valve 12', as shown in the drawings. Crystals can now fall under gravity though the valve but generally the flow (of solid material) is uncertain.

When the apparatus is activated, however, heat jacket 7 warms up, quickly melting flavour crystals touching the wall of the tank 3 next to the jacket 7. Socket 1 b has its own heating element 7a that melts crystals in the outlet 3b. So liquid flavour flows through the outlet 3b into the socket 1 b.

Adjoining socket 1b is a heating chamber 10' comprising a piston cylinder 10a including a piston 13 having a piston rod 13a that extends out of the cylinder 10a through a sealed end wall 10b. Piston 13 comprises a ring 13b which is a close sliding fit in the cylinder 10a and has a number of through bores 13c. Ring 13b is a loose fit on the end of piston rod 13a, captivated between end washer 13d and flange 13e. When the piston rod moves in a pressure stroke thereof (leftwardly in the drawing) against the reaction of liquid in the socket 1b, bores 13c of the piston ring 13b are closed by the flange 13e abutting the rear face of the ring 13b. Liquid flavour is forced back into the tank 3 by the piston 13 and a vacuum develops, to some extent, behind it, as well as some flavour leaking past and evaporating in the chamber 10'. When the piston moves back on its return stroke (rightwardly in the drawing) flange 13e separates from the rear face of the piston ring 13b and opens its bores 13c. The piston can move back without resistance into the chamber 10', liquid in the tank 3 returning under gravity to fill the chamber 10' in front of the piston 13.

Chamber 10' has its own heating jacket 7b that further heats liquid in the cylinder 10a. However, as well as heat from this, heat is gained from the mechanical agitation of the liquid flavour by the piston 13. It squirts liquid back up into the tank 3 under pressure so that the crystals in the tank are agitated, heated by the returned liquid and also pressed into contact with the wall of the tank 3 adjacent the jacket 7, whereby transfer of heat from the jacket to the contents of the tank is accelerated. The arrangement results in more rapid melting of all the additive in the tank 7.

Apparatus 1' is in the form of a "tank preparation unit" to rapidly heat and melt the additive content of the tank. Once melted, the tank 3 can be detached and transferred

to a standard flavour application. However, although not shown, a port could be provided in the socket 1b for liquid additive to be drawn off directly to an application device.

Finally, turning to Figure 15, piston rod 13a is connected to bridge 18 which has actuator rod extensions 20 connected at each end. Two pneumatic cylinders 22 drive actuator rods and their extensions 20 back and forth, operating the piston 13. During non-use, it is feasible that the cylinder 10' may be filled with solid additive. However, apart from controls that can detect non-movement of the piston 13 and stop it from trying to actuate for periods of time, non-movement thereof is, in fact, not seriously problematic. The cylinders 22 and they can be left actuating, although not moving, without causing any damage to the apparatus 1 , until the additive in the heating chamber 10' has sufficiently melted.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, additives or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed,

may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.