WO2023235902A1

WO2023235902A1 - Process and equipment for manufacturing cut rag

Info

Publication number: WO2023235902A1
Application number: PCT/ZA2022/050071
Authority: WO
Inventors: Klaus TIEFENBACHER; Kobus De Koker; Neels Peter KOK
Original assignee: Airbender Innovations (Pty) Ltd
Priority date: 2022-05-31
Filing date: 2022-12-19
Publication date: 2023-12-07

Abstract

A process and equipment for manufacturing cut rag is disclosed. The process includes the steps of obtaining threshed tobacco leaves in which leaf lamina is separated from leaf stem. The lamina is then subjected to a conditioning step in a conditioning cylinder (104) and then fed into a cutting machine (108) which cuts the lamina into strands. The cut lamina is cooled in a first cooling drum (110) and exposed to steam in an expansion tunnel (112). Thereafter, the lamina is dried with either co-current or counter-current airflow in a drum dryer (114) and then cooled in a second cooling drum (116) with low humidity cold air. Finally, the cut lamina is packaged on a packing platform (120) as cut rag.

Description

PROCESS AND EQUIPMENT FOR MANUFACTURING CUT RAG

CROSS-REFERENCE(S) TO RELATED APPLICATIONS

This application claims priority from South African provisional patent application number 2022/06026 filed on 31 May 2022, which is incorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to a process and equipment for processing tobacco. More particularly, the present invention relates to different processing techniques and equipment for manufacturing cut rag.

BACKGROUND TO THE INVENTION

Increased costs from tobacco leaf growing up to tobacco cut rag manufacturing has placed the total supply chain under pressure to reduce costs whilst maintaining the ability to manufacture tobacco products, such as cigarettes and new generation non-combustible products, complying to customer expectations and demand.

The cigarette consists of different components i.e. , non-tobacco material such as cigarette paper and filter material and the tobacco defined as “cut rag”. The tobacco component contributes by far the largest portion of the total cigarette cost. Therefore, the manufacturing process aims to reduce the amount of tobacco required whilst manufacturing cigarettes to a world class standard.

The international reference to tobacco utilization is the ability to manufacture the maximum number of cigarettes from a kilogram of tobacco conforming to set quality standards and market demand. The cigarette quality measurements correlating to the cigarette market demand are cigarette firmness, cigarette end loss and cigarette pressure drop

Cigarette firmness is the “hardness” of the cigarette the customer experiences when smoking and holding the cigarette between their fingers. Cigarette end loss refers to the visual appearance of the cigarette tip. The target is to have a smooth and filled tip with no loose tobacco. Cigarette pressure drop is the resistance the smoker will experience when drawing air through the cigarette whilst smoking. It is important to note that cigarette weight is set at milligram tobacco per volume e.g., 250mg/cm3. This allows calculating the amount of tobacco required per cigarette taking the cigarette dimensions into consideration. Dimensions of different cigarette brands can vary. Maintaining set targets of the three quality measurements defined above are a prerequisite for market satisfaction. However, the consistency thereof is as important as the consumer wants each cigarette to smoke the same.

Referring to tobacco quality, the global terminology for the tobacco used for cigarette manufacturing is cut rag. The two key quality measurements for cut rag used to measure the impact on the above cigarette quality measurements are cut rag filling power and cut rag length.

The cut rag filling power is defined as the resistance against pressure. This entails the amount of outwards pressure of the cut rag on the cigarette paper when pressed into the cigarette rod. Increased filling power will improve cigarette firmness, reduce end loss, and increase pressure drop. An increase in filling power correlates with potential reduction in cigarette weight whilst maintaining set standards. As a result, the cigarette density can be reduced resulting in improved tobacco utilization.

The cut rag length refers to the actual length of the tobacco strands in the cigarette. Optimum rag length and particle size distribution in the cigarette ensures homogeneous rod filling, consistency in pressure drop and improved cigarette tip quality i.e. , no loose ends.

The combination of cut rag filling power and cut rag length and width directly influences the required cigarette density to achieve set cigarette quality targets. Improving these two components is important to reducing costs.

The global standard on leaf processing is referred to as green leaf threshing (GLT). This entails receiving cured leaf from the tobacco farms. The leaf is classified through grades with codes defining quality and taste. The leaf is then conditioned and threshed where the lamina component is separated from the stem. Both products are dried and packed to moisture and temperature specifications.

Before being packed, the lamina goes through a redryer. To ensure homogeneous final packed lamina moisture, the lamina is dried typically to 10% before again reconditioned to the packing moisture of typically 12.5%. This step may cause damage to the tobacco cell by removing moisture from within the cell and lowering cell strength. The plant cuticular waxes may also be negatively impacted by this process which can affect aroma and taste. After the re-drying step, the lamina is packed/pressed into typically C48 cartons. The “C48” designation refers to the size of the cartons. The packed lamina dispatched from the green leaf threshing plants in C48 cartons is typically at a moisture in the order of 12.5% and at a weight per carton of 200kg. It is important to note that lamina at 12.5% moisture is brittle and very difficult to handle without degradation of the product. During the standard process, these lamina bales from the C48 cartons are mechanically sliced into slices which then go through a conditioning cylinder to increase the moisture from about 12.5 % to about 22%. The process of slicing these bales can further contribute to degradation of the brittle lamina. Therefore, the focus should be on preventing degradation of the tobacco cells during manufacturing while maintaining filling power.

Another challenge of current processes is consistency in temperature and moisture across different climates. Several steps of the current processes occur at ambient temperature and the tobacco product is exposed to the moisture content of the air that the production plant is located in. Minimising variance in temperature and moisture of the tobacco product can contribute to producing a more consistent and reliable product and enable better regulation of high standard cut rag.

Water stains are another problem currently experienced during tobacco processing. Water stains are wet spots of high-water concentration on the tobacco after conditioning. This negatively impacts filling power, taste, and visual appearance. The harsh conditions of the current processes cause cell damage to the tobacco plant which makes it more susceptible to water stains. Therefore, maintaining the cell integrity of the tobacco is important to address the issue of water stains.

The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge in the art as at the priority date of the application.

SUMMARY OF THE INVENTION

In accordance with an aspect of the invention there is provided a process for manufacturing cut rag, the process including the steps of: a) obtaining threshed tobacco leaves in which leaf lamina is separated from leaf stem; b) conditioning the lamina by exposing it to steam so as to raise the moisture content and temperature of the lamina; c) feeding the lamina into a cutting machine which cuts the lamina into strands; d) cooling the cut lamina without substantially reducing its moisture content; e) exposing the cut lamina to steam; f) drying the cut lamina with either co-current or counter-current airflow; g) cooling the cut lamina with low humidity cold air to reduce the moisture content of the cut lamina; and h) packaging the cut lamina as cut rag.

The threshed tobacco leaves may be obtained from a green leaf threshing facility.

The process may include a step of, after step a) and before step b), introducing the lamina into a blending silo by means of a movable conveyor which layers the lamina evenly in the blending silo.

Conditioning step b) may involve only saturated steam so as to avoid staining the lamina with water. Conditioning step b) may be carried out in a conditioning cylinder. During conditioning step b) the temperature may be raised to between 55 and 75 °C and the moisture content to between 22 to 28 %.

The process may include a step, after step b) and before step c), introducing the lamina into a bulking silo in which controlled fermentation may take place.

The cutting machine may cut the lamina into strands that are between 1.2 mm and 1.7 mm in width. The cutting machine may be a rotary drum with blades and a conveyor.

The cooling step d) may be carried out in a first cooling drum which includes paddles on which the cut lamina slides during rotation of the drum, thereby substantially reducing degradation of the cut lamina. The cooling step d) may reduce the temperature of the cut lamina to between 5 degrees and 10 degrees Celsius.

Step e) may be carried out in an expansion tunnel in which the steam is introduced from nozzles located both above and beneath a surface supporting the cut lamina. Step e) may convert moisture inside the cut lamina from liquid to vapour. Step e) may raise the temperature of the cut lamina to within 2 degrees of boiling temperature at a location where the process is taking place and the moisture content thereof to between 24% to 30%.

The drying step f) may be carried out in a drum dryer in which heated air can be configured to move in a counter-current direction from an exit of the drum dryer to an entrance of the drum dryer. The drum dryer may rotate and may include paddles to promote homogenous drying and minimise degradation.

During the drying step f) the moisture content of the cut lamina may be reduced to between 11 ,5 and 13,5 %.

The cooling step g) may be carried out in a second cooling drum having a perforated centrally extending pipe in which the low humidity cold air is introduced into the second cooling drum. The second cooling drum may rotate and may include segments in which the cut lamina slides. The cooling step g) may lower the temperature of the cut lamina to between 5 and 10 degrees Celsius.

The process may include a step, after step g) and before step h), introducing the cut lamina into a migration silo in which the temperature of the cut lamina may be permitted to gradually increase to ambient temperature.

During packaging step h), the cut lamina may be packaged into a carton on a vibrating platform so as to permit the cut lamina to settle.

The steps of the method may be performed in a single manufacturing location.

The process may be carried out from step a) onwards without using stem.

According to another aspect of the invention there is provided cut rag produced according to the process as described.

According to another aspect of the invention there is provided equipment for producing cut rag, comprising: a conditioning cylinder for conditioning the lamina by exposing it to steam so as to raise the moisture content and temperature of the lamina, a cutting machine for cutting the lamina into strands; a first cooling drum for cooling the cut lamina without substantially reducing its moisture content; an expansion tunnel for exposing the cut lamina to steam; a drum dryer for drying the cut lamina with either co-current or counter-current airflow; and a second cooling drum for cooling the cut lamina with low humidity cold air to reduce the moisture content of the cut lamina. The equipment for producing cut rag may include a vibrating platform for packing cut rag.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

Figure 1 is a flow diagram showing the different equipment used at each stage of the process;

Figure 2 is a side view of a conditioning cylinder;

Figure 3 is a side view of a blending and bulking silo for the lamina;

Figure 4 is a side view of a first cooling drum;

Figure 5 is a cross-sectional view of the first cooling drum of Figure 4 showing the cut lamina movement;

Figure 6 is a side view of an expansion tunnel;

Figure 7 is a side view of a drum dryer;

Figure 8 is a cross-sectional view of the paddles within the drum dryer of Figure 7; and

Figure 9 is a three-dimensional view of a packing platform.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

In an embodiment of the invention there is disclosed a process and equipment for manufacturing cut rag. The process can be divided into several steps, beginning with green leaf threshing of the tobacco leaves where the lamina and stem are separated. The present invention focusses on the lamina portion and the processing thereof into cut rag. Cut rag refers to tobacco that has been cut into strips or strands for use in cigarettes or other tobacco utilizing methods and is also referred to as simply “rag”.

Figure 1 sets out the order in which the pieces of equipment are used during the process. Each piece of equipment is associated with a different step in the process for manufacturing cut rag. The green leaf threshing (101) refers to a process step.

The steps of the process may comprise:

• obtaining threshed tobacco leaves in which leaf lamina is separated from leaf stem;

• blending and mixing the different lamina qualities using a blending silo; • conditioning the lamina by exposing it to steam so as to raise the moisture content and temperature of the lamina;

• bulking the lamina to allow heat and moisture migration through the lamina layers;

• feeding the lamina into a cutting machine which cuts the lamina into strands;

• cooling the cut lamina whilst maintaining its moisture content;

• exposing the cut lamina to steam;

• drying the cut lamina with either co-current or counter-current airflow;

• cooling the cut lamina with low humidity cold air with minimum impact to the moisture content of the cut lamina; and

• packaging the cut lamina as cut rag.

There may also be additional steps that can be included in the process, and those are discussed in more detail below.

Green Leaf Threshing (101)

The initial step in most tobacco processing methods is green leaf threshing (GLT). During threshing, the tobacco leaf is broken up into mainly lamina and stem. The lamina components are separated from the stem by passing the leaves through a series of threshing machines and separators. As mentioned, the present invention focusses on lamina processing and not stem even though stem processing is possible with this process. The stem should preferably be removed from the process at this point. Any standard GLT method may be used to produce lamina and stem for further processing.

The following process may be integrated into the GLT plant. After the tobacco undergoes green leaf threshing the following process steps may be conducted at the GLT plant. The advantage of having the process done at one location may be that there is no need to subject the tobacco to an additional drying and packaging step in order to transport it to a different location for further processing into cut rag. This may save time and costs and could also contribute to maintaining the integrity of the tobacco cells, thereby increasing filling power, as the tobacco may not be subjected to harsh drying and packaging conditions. If the tobacco cells are protected it may result in reduced degradation of the tobacco and accordingly less dust and waste, thereby providing improved process yield. Also, by preserving the integrity of the tobacco cells, this process may better maintain the natural smoke and taste characteristics associated with the tobacco.

Blending Silo (102)

After green leaf threshing (101), the lamina may be transported to a blending silo (102). An embodiment of a blending silo is shown in Figure 3. The lamina is layered within the blending silo to blend the lamina and allow for even temperature and moisture dispersion. A conveyor system (136) may transport the lamina (132) from the GLT to the blending silo and be configured to layer the lamina evenly in the blending silo. The doffers (138) at the silo exit are designed to mix the layers with minimum degradation. The blending, bulking and migration silo designs may be similar.

No early stage drying

During standard tobacco processing methods, it is common to subject the tobacco to a drying step shortly after threshing to lower the tobacco’s moisture. However, a drying step so early in the processing may cause damage to the lamina cells. The cells may harden which increases the chances of cell breakage during packaging. By leaving out a drying step at this early stage of the process, the lamina’s elasticity may be improved and may help to preserve the tobacco’s taste.

The aim is therefore to protect the lamina cells. Not having an early stage drying step may protect the plant cuticular waxes and contribute to preserving the natural aroma and taste of the tobacco. Also, it may contribute to the cell mesophyll maintaining cell strength.

Conditioning Cylinder (104)

Figure 2 shows an embodiment of a conditioning cylinder (104) wherein the lamina is conditioned by exposing it to steam so as to raise the moisture content and temperature thereof. During the conditioning step only steam or saturated steam is used. The aim is to avoid water stains, i.e., wet spots of high-water concentration on the tobacco after conditioning because water stains may negatively impact filling power, taste, and visual appearance.

The steam allows for homogeneous moistening. Natural cell “expansion” is achieved with high temperature water saturation. When referring to “expansion” it should be understood to mean that the tobacco cells do not necessarily literally expand but rather it is referring to the increase in moisture within the cells i.e., the opposite of the cells losing moisture and shrinking.

A key aspect on this approach versus the global standard process is the increase in incoming moisture allowing “soft conditioning” using mainly steam. This creates a high humidity environment allowing the tobacco to naturally absorb the water from the environment. This may prevent water stains whilst optimum cell absorption of the heat and water is achieved. This conditioning step may be applicable to all types of leaf as well as leaf gualities. During the conditioning step, the temperature may be raised to between 55°C and 75°C and the moisture content to between 22 % to 28 %.

Below is an example of the moisture values during conditioning of the current invention compared to a standard process:

As shown in Figure 2, the cylinder (104) is divided into four zones (Z1 , Z2, Z3 and Z4). Steam nozzles (122, 124, 126) are arranged at the cylinder inlet. The aim of the design is to generally minimise degradation of the lamina entering the cylinder at reduced moistures and gradually increase the fall height in the cylinder as the moisture increases to ensure homogeneous moistening with minimum degradation. The cylinder has pins for mixing the lamina within the cylinder to ensure homogenous heat transfer. The pins differ in height between the different zones to accommodate the lamina at different moisture contents and minimise degradation thereof by adjusting the fall height of the lamina. The conditioning cylinder may be at an angle to promote movement of the lamina from the inlet towards the outlet of the cylinder. The cylinder may rotate or move as the lamina moves through it to accommodate homogenous moisture distribution.

The lamina enters the cylinder at Zone 1 and the following process occurs:

Zone 1 (Z1) - Short thick pins increase in height from the cylinder inlet up to Zone 2 to minimize degradation and breakage with reduced fall height to allow heat transfer and conditioning by steam nozzle 1 (122). The moisture of the lamina may be increased by ±1 %.

Zone 2 (Z2) - Zone 2 has pins with an increased length and reduced diameter versus Zone 1 to increase the lamina lift in the drum diameter with exposure of the lamina to the high humidity steam filled air. This promotes homogenous conditioning by steam nozzle 2 (124). The moisture of the lamina may be increased by ±1.5%.

Zone 3 (Z3) - Zone 3 has pins with an increased pin length but with the same diameter as in Zone 2 to lift the lamina to fill the total diameter of the drum to minimise the chance of water stains by steam nozzle 3 (126). Steam atomized water may be used.

Zone 4 (Z4) - Pin length reduces from Zone 3 to the cylinder exit at Zone 4 allowing homogeneous flow at the cylinder exit. Leaf smoking quality is largely linked to the stalk position of the leaf. The top half of the plant mostly correlates to good smoking quality with the lower portion linked to reduced aroma and taste. The bottom leaf on the tobacco plant is defined as “lugs” and is mostly associated with reduced leaf and smoking quality. When conditioned, the aroma coming off the leaf strips mostly correlates with plant position and leaf type. In the process of conditioning, unwanted aroma with different leaf qualities, can be removed from the cylinder using the outlet (130). The air removed is then replaced with fresh air through the air intake (128). This concept may reduce the negative impact on the final grade smoke characteristics associated with low quality lamina.

The above conditioning methodology allows storage of the lamina with little to no risk of oversaturated spots on the lamina which may cause mould or rot. The cylinder moisture control using mostly steam at constant volume and constant product flow ensures homogeneous and consistent moisture after conditioning.

Bulkina Silo (106)

Figure 3 demonstrates the design of an embodiment of a bulking silo to cover the lamina for storage as well as the design for feeding doffers. The doffer design aims to enable a natural fall of the lamina from the belt. This contrasts with the current global practise of combing the lamina from the silo which may have a negative impact on the lamina and contribute to degradation.

The lamina (132) is transported on a blending car (134) and falls onto a conveyor (136). At the end of the conveyor (136) are doffers (138) arranged to receive the lamina (132) and allow for a more natural fall from the conveyor (136). Figure 3 shows the stages of the lamina moving from the blending car (134) to the conveyor (136) and then finally being received by the doffers (138).

The bulking silo allows for controlled storage time, at a set moisture target and at a set temperature target where the product may be closed off from environmental conditions.

Controlled fermentation may also occur during this step to facilitate colour and aroma changes of the tobacco. During fermentation, the silo may be closed with a cover and conditions such as temperature and moisture may be monitored to allow for the required fermentation conditions.

The present invention can be adapted to process different grades of tobacco. Although the filling power on each new grade will remain the focus, the impact on cigarette smoke quality i.e. , taste, will always be a consideration. The process according to the invention may treat low quality/low- cost leaf to achieve optimum filling power but with satisfactory taste. Cutting Machine (108)

The next step in the process is to feed the lamina into a cutting machine (108) which cuts the lamina into strands. The cutting machine should be configured to cut the lamina into strands that are between 1.2 mm and 1.7 mm in width. This width is generally wider than current global practice. The reason being that during the current process, physical expansion of the lamina during the expansion step is not achieved on the same level as is seen in other standard processes. Therefore, to achieve cut rag of a sufficient width and length during the current process, the lamina is cut into bigger strands than the normal practice. Several different embodiments of cutting machines may be used to do this. For example, the cutting machine may be a rotary drum with blades or knives spaced around the drum.

First Cooling Drum (110)

Following the cutting step, the cut lamina moves to a cooling step which is carried out in a first rotating cooling drum (110) as show in Figure 4.

The first cooling drum consists of a cooling zone (143) and a mixing zone (141). The cooling zone has a perforated core (144) and the diameter of the drum is divided into four segments as shown in Figure 5. Exiting the cooling zone, small paddles (140) in the first cooling drum diameter mix the cut lamina (132) coming from the cooling zone. During this step, the lamina is cooled without substantially reducing its moisture content.

The first cooling drum (110) includes paddles (140) as shown in Figure 5 on which the cut lamina (132) slides during rotation of the first cooling drum (110) with little to no dropping of the lamina thereby substantially reducing degradation of the lamina. Also, the paddles may assist in homogenous air distribution by continuously changing the surface of lamina exposed to cold air.

In the cooling zone (143), the cut lamina slides through the segmented areas and across the perforated core (144) introducing the cooled air. This allows homogeneous cooling with little to no degradation.

A chiller (142) is used to pump cold, moisturised air into the first cooling drum (110) via a perforated core (144). The cooling step reduces the temperature of the cut lamina to between 5 degrees and 10 degrees Celsius. However, the cool air may also be moisturised with the aim of not reducing the moisture content of the lamina cells. An increase in moisture of the cut lamina may also occur during this step. The first cooling drum (110) has a perforated core (144) for introducing the moisturised cold air into the first cooling drum to ensure a more homogenous air distribution over the whole drum. The last section of the drum (the mixing zone) conveys the cut lamina out of the first cooling drum with minimum degradation due to paddle design that facilitates a sliding motion rather than falling. The first cooling drum may include a dust collection cyclone (146).

Applying cut lamina cooling after cutting allows for more consistency in the temperature of the cut lamina before the expansion step thereby neutralising seasonal variations in ambient temperatures.

The difference and rate of change from water to vapor in the tobacco cells are essential for the next step of the process. This cooling step is therefore important to cool the lamina preheating so as to increase the temperature difference at the next step. The air-cooling process may use a water curtain for cooling and humidifying the air. Increasing of the moisture of the lamina whilst cooling, is a positive contributor to expansion i.e., increased water in the cells.

Expansion Tunnel (112)

The lamina moves from the cooling step to an “expansion” tunnel (112) where the lamina is exposed to steam. As explained previously, when referring to “expansion” it is not meant to be interpreted as a structural increase in size but rather an increase in moisture within the lamina cells.

As shown in Figure 6, steam is introduced into the expansion tunnel (112) from nozzles (150) located both above and beneath a surface supporting the cut lamina. The steam raises the temperature of the cut lamina to boiling temperature (100°C ± 2°C) at a location where the process is taking place (boiling point may differ depending on the altitude above sea level and weather conditions) and the moisture content thereof to between 24 to 30 %. The main aim of this step is to convert moisture inside the cut lamina from liquid to vapour as quickly as possible.

Leaf characteristics include the leaf stem component which has well developed cells where expansion is relatively easy when changing the water in the cells into vapor. Contrary to stem, the lamina portion is very hygroscopic and as such does not have enclosed cell structures. Therefore, heat transfer and heating of the water in the lamina cells to achieve optimum expansion must be more intensive. Dry Ice Expanded Tobacco (DIET) process is one of many globally accepted methods used for lamina expansion and is used by most cigarette manufacturers. As an example, this concept treats cut rag with impregnation of the cell structure with liquid carbon dioxide under pressure. Releasing the pressure to atmosphere, the carbon dioxide within the tobacco solidifies into dry ice. The impregnated tobacco is then rapidly expanded in a stream of hot gas and after cooling reordered to set moisture targets.

The DIET process, as is the case with most of the current gas medium expanded products, is a proven concept but has several disadvantages. These processes are cost intensive. Smoking quality may be sacrificed for filling power as these products are designed solely as a filler and when added into a blend, the blend grade configuration must be adjusted to compensate and maintain the new blend smoke characteristics. This in most cases comes at an additional cost as the replacement leaf must be of good smoking quality. Therefore, an alternative process is suggested.

It is not the amount of heat applied to the product for expansion, but the rate of heat transfer onto the product with rapid changing of the water in the cells to vapor creating a high pressure in the cells. The measure of success is the actual product temperature achieved after expansion at boiling point i.e. , 100°C at sea level.

As shown in Figure 6, steam nozzles and steam application are used in two segments, one from the top and one from the bottom. The top nozzle (150b) configuration uses an arrangement of nozzle rows over the width of the trough. Nozzle rows one, two and three are at angles blowing the product towards the exit of the tunnel (112) with nozzle rows four and five at angles to blow towards the tunnel entrance (152). The steam pressure is optimized per nozzle row to “capture” the product in this heating zone for optimum and rapid heat transfer.

The bottom nozzle (150c) configuration consists of a steam manifold with a range of nozzle rows over the width of the trough. Steam direction from the nozzles is perpendicular to the trough floor blowing into the captured product in the heating zone. This concept ensures optimum heat transfer to each particle in the heating zone ensuring homogeneous heat transfer and expansion. The reduction in height of the trough towards the exit of the tunnel (112) may create a venturi effect. This concept converts a high pressure at process temperature to a low pressure with increased temperature maintaining cell pressure up to the drier inlet (next step of the process).

The cell structure and hygroscopic nature of the lamina does not allow for big volumetric increase in volume if not using carbon dioxide (as is the case with the current process). Therefore, as discussed above at the cutting step, the cut width of the lamina is optimized to physically deliver the volume after the natural expansion to be like cut rag from the DIET process.

By controlling the temperature of the cut lamina from the cooling step to the expansion step, it is possible to minimise the effect of seasonal changes on temperature and humidity of the tobacco, thereby allowing for a more consistent product. It also allows for more consistent expansion of the lamina.

Drum Dryer (114)

After the lamina has moved through the expansion tunnel, it is transported to a rotating drum dryer (114) to lower the moisture content thereof. The design of the drier aims to facilitate homogeneous drying whilst maintaining expansion and filling power.

As shown in Figure 8, the drier paddle (160) configuration is designed to distribute the product as a curtain across the full diameter of the rotating drum allowing the hot air to absorb the water optimally and homogeneously from the tobacco. This paddle design may be used in other drums and tunnels of the process, for example in any of the cooling drums.

As shown in Figure 7, the most important area in this concept is at the drier inlet (162). At this point the tobacco is typically at 95°C to 99°C (depending on altitude) with a high percentage surface moisture. The drier (114) is designed to dry using air flow in line with the tobacco flow i.e. , co-current drying as well as air flow against the flow of the tobacco i.e., counter-current drying. During this drying step the moisture content of the cut lamina may be reduced to between 11 ,5 and 13,5 %.

With co-current drying the air is heated and enters the drier at the inlet (162) of the drier. This air is low in humidity i.e., hot, and dry air and as a combination thereof apply high moisture removal i.e., shock treatment to the tobacco arriving from the expansion unit. This methodology of drying will generally be used for the low-quality grades of tobacco where the priority is filling power.

With counter-current drying the air is heated but enters the drier at the exit side (164) of the drier. The dry hot air then picks up moisture as it goes through the length of the drier towards the entrance. The water load in the air may increase to a point where the air is 100% saturated. At the drier entrance the air humidity and temperature are in equilibrium with the tobacco at this point and have a defined impact on the incoming product. A “wet zone” is created when the hot and humid air comes into contact with the hot lamina. This methodology of drying will generally be used for the high-quality full flavour grades of tobacco where the priority is taste whilst achieving good filling power.

Of note is that the drum dryer (114) of the current process can do both co-current and counter current drying. It has a selection chamber (166) for changing from co-current drying to countercurrent drying.

Second Cooling Drum (116)

After drying, the cut lamina is still at a slightly higher moisture content than the target moisture and at a high temperature. The cut lamina is now in a phase of expansion and the cells are generally optimally enhanced. However, this is also an important stage for retaining the potential filling power increase into the cut lamina strands.

The process used for the above is to use low humidity cold air to implement a rapid change in temperature. A second cooling drum (116), similar in design to the first cooling drum (110) as shown in Figure 4, may be used for this step. The cut lamina flow may be divided into 4 streams in the cooler drum, as shown in Figure 5. The cold air is blown onto the lamina from the core of the drum, i.e., the second cooling drum has a perforated centrally extending pipe in which the low humidity cold air is introduced into the second cooling drum while the drum rotates. This ensures optimum cold air distribution in the product for homogeneous cooling. This cooling step lowers the temperature of the cut lamina to between 5 and 10 degrees Celsius. At these low temperatures, the cut rag may become very brittle. To prevent breakage, the product slides through the segments with little to no drops to minimise degradation. As the cool air contains little to no moisture, there may be a reduction in moisture of the cut rag.

Migration Silo (118)

After cooling, the lamina may be conveyed using belt conveyors with minimum drops to a migration silo (118). The temperature of the cut lamina is permitted to gradually increase to ambient temperature within the migration silo. The migration silo may have a similar doffer design to the bulking and blending silo shown in Figure 3. As with those silos, the migration silo’s doffers may be set at an angle to facilitate the natural fall of the cut rag to minimise breakage when extracted from the silo. Packing Platform (120)

Finally, as shown in Figure 9, the cut lamina is packaged as cut rag into a carton (170) on a vibrating platform (120) to permit the cut rag to settle. The vibrating platform allows for the cut rag to fill open spaces within the carton (170) without the need for compression. However, in some embodiments, mechanical compression of the cut rag in the carton (170) may be required. Applying pressure to the cut rag during packaging may damage the cut rag and therefore the vibrating platform packaging is preferred to minimise degradation. The carton may be any standard container suitable for cut rag, such as a C48 box.

The process described according to the invention is also well suited for manufacturing final cut rag to be used in the Heat-not-Burn (HnB) products. Whereas the current trend is to use specially treated reconstituted tobacco, this concept describes the process and methodology to enable using cut rag in the HnB products. The key components used in this concept are leaf grading, humectant application, HnB capsule density (final cut rag filling power, final cut rag cut width and rag length, final cut rag moisture).

The success of using leaf and cut rag for the HnB capsule is to generate a “smoking” experience with high aroma and impact i.e. , delivering a smoke with reduced levels of harmful chemicals but maintaining a high smoke quality product. To achieve this, leaf with high aroma, high nicotine (>5.0%) and high sugar (>17.0%) with low Chloride (<0.40%) is well suited. This combination is typical for example of leaf grown in certain regions in South Africa.

Humectants, generally glycerine and propylene glycol, are the main components of the atomizing agent in heat-not-burn tobacco products (HnB), which affect the smoke release of HnB significantly. The current global concept is to use humectants at high application rates i.e., >15%, to act as a vapor-carrier for the nicotine generated during heating of the product used in the capsule. With the process proposed here, applying high percentages of humectant can be done without any concerns on spots of high concentration of humectant on the leaf. The high amount of sugar in tobacco leaves from some regions also reduces the necessity for high humectant application and further reduces the levels of harmful chemicals.

With HnB, the product used in the capsule is only heated which then generates a flavourful nicotine-containing vapor. To ensure optimum vapor generation, heat transfer between the cut rag particles is of the utmost importance. Optimum filling power is essential for favourable compacting of the tobacco strands resulting in good heat transfer. The current claimed process is well aligned to generate the required filling power with enhanced taste. The combination of cut rag filling power, cut width and final cut rag length is very important for the HnB product. In the case of the HnB product, the aim is to ensure a high-density compacted product in the capsule to enhance heat transfer and vapor forming during smoking. Supplying the threshed lamina directly from the threshing plant allows setting optimum threshing targets i.e., actual particle size and the distribution thereof. This, combined with the cut width is used to ensure optimum cut rag length in the capsule. The moisture content in the final cut rag is reduced to enhance heat transfer and vapor generation mainly from the humectant.

To ensure quality control during the process, sensors may be placed within the different pieces of equipment throughout the process to allow for measurements such as temperature and moisture content. Optimum control actuators and equipment may also be included throughout the process equipment to achieve and maintain set points. For example, homogeneous and constant heat transfer to each particle is important during the steam heating step in the expansion tunnel. This also means that the amount of heat transfer in relation to the volume/weight of the product must be constant. To achieve the above, constant dry weight feed forward control may be used pre-expansion. This relates to increasing the flow rate when the moisture content measured on a flow control conveyor is higher than target and vice versa if the moisture is lower than target.

In another example, to ensure optimum drier control, constant water load feed forward control may be applied pre-drying. The expansion tunnel may have a water moistening nozzle at the expansion tunnel inlet that may be used to apply a calculated amount of water, based on the product flowrate and moisture pre-expansion, to ensure constant water load to the drier. Optimum regulating and control of the steam pressure on the steam nozzles may assist in facilitating constant heat transfer and consistency in expansion. The above control measures may allow for constant water load to be removed by the drier thereby ensuring homogeneous drying.

The two main contributors to improved cigarette quality and tobacco utilization are final cut rag filling power and final cut rag length. Both components are impacted throughout the process and are important for successful product development and cigarette quality. Therefore, a key aspect for the product produced by means of the current invention is to protect particle size and final cut rag length throughout the process.

The aim of the inventive process is to achieve a good combination of filling power and cut rag length and width for optimum tobacco utilization close to or on par with what is currently achieved with gas expanded products but with the benefit of having little to no negative impact on cigarette aroma and taste and at a reduced cost. Combining the increased filling power and cut rag length allows for improved tobacco utilization. With little to no negative impact on taste and aroma, the new filler may be used in existing blends without the need to incorporate blend changes achieving improved tobacco utilization whilst maintaining smoke characteristics. The expansion process according to the present invention is a combined process of applying product cut width, product moisture, heat transfer, product temperature, product drying and product cooling to enhance, capture and set cell resistance against pressure.

Throughout the process and at each step, a big focus is the preservation of the lamina cells and minimising cell degradation. For example, this process does not rely on a harsh drying process shortly after GLT. Also, the current process does not require mechanical compression to pack the cut rag.

Finally, by controlling the moisture content and temperature at almost every step of the process, it is possible to minimise the variance of temperature and moisture of the tobacco. A variance in temperature and humidity based on seasonal changes and location can have a significant impact on the final product. Therefore, being able to minimise this effect by controlling the temperature and moisture will allow for a more consistent product.

The foregoing description has been presented for the purpose of illustration; it is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above disclosure.

The language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based hereon. Accordingly, the disclosure of the embodiments of the invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.

Finally, throughout the specification and accompanying claims, unless the context requires otherwise, the word ‘comprise’ or variations such as ‘comprises’ or ‘comprising’ will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims

CLAIMS:

1. A process for manufacturing cut rag, the process including the steps of: a) obtaining threshed tobacco leaves in which leaf lamina is separated from leaf stem; b) conditioning the lamina by exposing it to steam so as to raise the moisture content and temperature of the lamina; c) feeding the lamina into a cutting machine (108) which cuts the lamina into strands; d) cooling the cut lamina without substantially reducing its moisture content; e) exposing the cut lamina to steam; f) drying the cut lamina with either co-current or counter-current airflow; g) cooling the cut lamina with low humidity cold air; and h) packaging the cut lamina as cut rag.

2. The process as claimed in claim 1 , wherein the threshed tobacco leaves are obtained from a green leaf threshing facility.

3. The process as claimed in claim 1 or 2, wherein the process includes a step of, after step a) and before step b), introducing the lamina into a blending silo (102) by means of a movable conveyor (136) which layers the lamina evenly in the blending silo (102).

4. The process as claimed in any one of the preceding claims, wherein conditioning step b) involves only saturated steam so as to avoid staining the lamina with water.

5. The process as claimed in any one of the preceding claims, wherein the conditioning step b) is carried out in a conditioning cylinder (104).

6. The process as claimed in any one of the preceding claims, wherein the conditioning step b) raises the temperature to between 55 and 75 °C and the moisture content to between 22 to 28 %.

7. The process as claimed in any one of the preceding claims, wherein the process includes a step, after step b) and before step c), of introducing the lamina into a bulking silo (106) in which controlled fermentation takes place.

8. The process as claimed in any one of the preceding claims, wherein the cutting machine (108) cuts the lamina into strands that are between 1.2 mm and 1.7 mm in width.

9. The process as claimed in any one of the preceding claims, wherein the cutting machine (108) is a rotary drum with blades and a conveyor.

10. The process as claimed in any one of the preceding claims, wherein the cooling step d) is carried out in a first cooling drum (110) which includes paddles (140) on which the cut lamina slides during rotation of the drum (110), thereby substantially reducing degradation of the cut lamina.

11. The process as claimed in any one of the preceding claims, wherein the cooling step d) reduces the temperature of the cut lamina to between 5 degrees and 10 degrees Celsius.

12. The process as claimed in any one of the preceding claims, wherein step e) is carried out in an expansion tunnel (112) in which the steam is introduced from nozzles (150) located both above and beneath a surface supporting the cut lamina.

13. The process as claimed in any one of the preceding claims, wherein step e) converts moisture inside the cut lamina from liquid to vapour.

14. The process as claimed in any one of the preceding claims, wherein step e) raises the temperature of the cut lamina to within 2 degrees of boiling temperature at a location where the process is taking place and the moisture content thereof to between 24 to 30%.

15. The process as claimed in any one of the preceding claims, wherein the drying step f) is carried out in a drum dryer (114) in which heated air can be configured to move in a counter-current direction from an exit (164) of the drum dryer (114) to an entrance (162) of the drum dryer (114).

16. The process as claimed in claim 15, wherein the drum dryer (114) rotates and includes paddles (160) designed to promote homogenous drying and minimise degradation.

17. The process as claimed in any one of the preceding claims, wherein during the drying step f) the moisture content of the cut lamina is reduced to between 11 ,5 and 13,5 %.

18. The process as claimed in any one of the preceding claims, wherein the cooling step g) is carried out in a second cooling drum (116) having a perforated centrally extending pipe in which the low humidity cold air is introduced into the second cooling drum (116).

19. The process as claimed in claim 18, wherein the second cooling drum (116) rotates and includes segments in which the cut lamina slides.

20. The process as claimed in any one of the preceding claims, wherein the cooling step g) lowers the temperature of the cut lamina to between 5 and 10 degrees Celsius.

21. The process as claimed in any one of the preceding claims, wherein the process includes a step, after step g) and before step h), of introducing the cut lamina into a migration silo (118) in which the temperature of the cut lamina is permitted to gradually increase to ambient temperature.

22. The process as claimed in any one of the preceding claims, wherein during packaging step h), the cut lamina is packaged into a carton on a vibrating platform (120) so as to permit the cut lamina to settle.

23. The process as claimed in any one of the preceding claims, wherein the steps of the method are performed in a single manufacturing location.

24. The process as claimed in any one of the preceding claims, wherein the process is carried out from step a) onwards without using the leaf stem.

25. Cut rag produced according to the process as claimed in any one of claims 1 to 24.

26. Equipment for producing cut rag according to the process of any one of the preceding claims, comprising: a conditioning cylinder (104) for conditioning the lamina by exposing it to steam so as to raise the moisture content and temperature of the lamina, a cutting machine (108) for cutting the lamina into strands; a first cooling drum (110) for cooling the cut lamina without substantially reducing its moisture content; an expansion tunnel (112) for exposing the cut lamina to steam; a drum dryer (114) for drying the cut lamina with either co-current or countercurrent airflow; and a second cooling drum (116) for cooling the cut lamina with low humidity cold air. Equipment for producing cut rag as claimed in claim 26, including a vibrating platform (120) for packing cut rag.