A flow-directing apparatus for a furnace for curing tobacco

Abstract

There is provided a flow-directing apparatus for a furnace for curing tobacco, the flow-directing apparatus comprising: one or more flow guides arranged to form a primary fluid flow path to guide a primary fluid flow from a primary combustion chamber of the furnace to a mixing region of the furnace; and one or more bypass channels arranged to form a secondary fluid flow path for receiving a secondary fluid flow from an inlet, wherein the secondary fluid flow path bypasses at least part of the primary fluid flow path, wherein an outlet of the one or more bypass channels is arranged to feed into the mixing region to cause the primary fluid flow and the secondary fluid flow to mix.

Description

[0001] AL Ref: P46838WO | JTI Ref: 6775 1

[0002] A Flow-directing Apparatus for a Furnace for Curing Tobacco

[0003] The present disclosure relates to a flow-directing apparatus for a furnace for curing tobacco, a mould for forming the flow-directing apparatus, a method of manufacturing the flow-directing apparatus, a furnace for curing tobacco and a method of heating a furnace for curing tobacco using the flow-directing apparatus.

[0004] Background

[0005] A flue-cured tobacco furnace is a specialised heating system used in the process of curing tobacco leaves. Flue curing is a method of drying tobacco leaves where heat is applied indirectly, using a furnace that channels the heat through flues (metal pipes) inside a barn or curing structure, without exposing the leaves to smoke.

[0006] A furnace typically includes a heat source, such as wood, coal or the like, which can be burnt to provide hot air / exhaust into the flues, which travel through the barn. In a typical furnace, the primary combustion occurs in a main chamber where the fire burns freely. The resulting heat, smoke, and gases then travel through the flue channel (heat exchanger) and are directly expelled out of the chimney. During this process, the heat is often not fully utilized and is consequently lost to the atmosphere, leading to inefficiency in heat conversion and high energy consumption.

[0007] Traditionally, farmers manually control the temperature in the barn by adjusting the level of fuel input into the furnace.

[0008] However, traditional barns are typically made of rudimentary materials and construction and often suffer from inefficiencies in fuel consumption and emissions control. The need for a cost-effective solution that can be integrated into existing systems without substantial modifications is critical for operational cost reduction and environmental compliance.

[0009] In some parts of the world, the curing process can account for a significant portion of overall emissions and carbon use in the process of producing tobacco for use in tobacco consumables. AL Ref: P46838WO | JTI Ref: 6775 2

[0010] It is the object of the invention to overcome at least some of the above referenced problems.

[0011] Summary

[0012] According to the present disclosure there is provided a flow-directing apparatus, a furnace for curing tobacco, a mould for forming the flow-directing apparatus, a method of manufacturing the flow-directing apparatus, a furnace for curing tobacco and a method of heating a furnace for curing tobacco using the flow-directing apparatus as set out in the following features.

[0013] In one aspect, there is provided a flow-directing apparatus for a furnace for curing tobacco, the flow-directing apparatus comprising: one or more flow guides arranged to form a primary fluid flow path to guide a primary fluid flow to a mixing region; and one or more bypass channels arranged to form a secondary fluid flow path for receiving a secondary fluid flow from an inlet, wherein the secondary fluid flow path bypasses at least part of the primary fluid flow path, wherein an outlet of the one or more bypass channels is arranged to feed into the mixing region to cause the primary fluid flow and the secondary fluid flow to mix.

[0014] The flow-directing apparatus creates a secondary fluid flow within the furnace. The secondary fluid flow passes through bypass channels within the flow-directing apparatus. The secondary fluid flow is heated as it passes through the bypass channels and so a heated source of secondary fluid is provided to a mixing region, downstream of the primary combustion chamber to facilitate a secondary combustion process. The secondary combustion process effectively ignites waste gases, such as carbon monoxide, and residual particles from the primary combustion. The secondary combustion process provides additional heat and therefore boosts the furnace’s overall efficiency. This secondary combustion process also increases the efficiency of the furnace by reducing fuel consumption.

[0015] The primary fluid flow comprises fluid received from the primary combustion chamber. The primary fluid flow may flow over (e.g. be guided by) a sloped base region of the apparatus to the mixing region in which it mixes with the secondary fluid flow. The secondary fluid flow may flow below an underside wall of the base region of the apparatus and then through the one or more bypass channels to the mixing region in AL Ref: P46838WO | JTI Ref: 6775 3 which it mixes with the primary fluid flow. The mixed fluid may then flow out of the outlet of the apparatus.

[0016] The one or more flow guides may comprise one or more columns. The columns provide a structural guide to direct the primary fluid flow through the flow-directing apparatus. The columns also act to “take up space” or restrict the flow of primary fluid flow through the flow-directing apparatus, thereby reducing the overall flow rate, which results in a better heat exchange within the barn due to the fluid moving slower.

[0017] The one or more columns may define one or more apertures between adjacent columns, wherein each aperture comprises a throat to restrict the primary fluid flow. The throat represents the smallest dimension of the apertures and is a key factor in restricting flow rate.

[0018] The outlet of the bypass channels may be located downstream of the throat in relation to the primary fluid flow. That is to say that the primary fluid flow may be funnelled in a direction towards the outlet of bypass channels to enable the primary and secondary fluid flows to effectively mix to promote secondary combustion.

[0019] The one or more flow guides may comprise a sloped base region to guide the primary fluid flow. The sloped base region further aids to restrict the primary fluid flow to reduce the resultant speed at which the combined primary fluid flow and secondary fluid flow exits the flow-directing apparatus. This results in an improved heat transfer between the flue and the surrounding environment within the barn as the combined fluid travels at a slower speed through the flue within the barn.

[0020] The outlet of the one or more bypass channels may be defined, at least in part, by the sloped base region to provide the secondary fluid flow to the mixing region. That is to say that the outlet of the one or more bypass channels is formed in the sloped base region. The secondary fluid flow travels through the bypass channels and is provided to a region above the sloped base region.

[0021] The one or more bypass channels may be integrally formed with the base region and extend from the inlet located in an underside wall of the base region to an upper wall of the sloped base region. Providing the bypass channels as part of the flow-directing apparatus provides a means for pre-heating the secondary fluid flow before it enters AL Ref: P46838WO | JTI Ref: 6775 4 the mixing region. The flow-directing apparatus is heated due to the primary fluid flow passing over the sloped base region. The primary fluid flow represents the exhausts / gases / particles from the primary combustion chamber. As such, the secondary fluid flow is heated as it travels within the one or more bypass channels, which aids to cause the secondary combustion.

[0022] There may be provided a slot cover configured to engage with a sloped recess of the primary combustion chamber, the slot cover arranged to abut the base region of the flow-directing apparatus. The slot cover aids with splitting the incoming fluid flow into a primary fluid flow and a secondary fluid flow. In this context, the incoming fluid flow may be ambient air that flows via an air vent into a furnace that includes the flowdirecting apparatus. The slot cover may be a triangular plate that extends from the flowdirecting apparatus and engages with a slot (or secondary opening) of a primary combustion chamber. The slot cover may be mild steel. The slot cover may have a bed of fuel, such as charcoal (and or wood) on top of it. The slot cover allows air (secondary fluid flow) to pass underneath the slot cover towards a bottom of the flowdirecting apparatus to the inlet of the bypass channels. The fuel on top of the slot cover heats the slot cover and hence, the air (secondary fluid flow) that flows under the slot cover will be “pre-heated”. The secondary fluid flow is further heated as it passes through the bypass channels. For secondary combustion to occur (i.e. the combustion of the otherwise waste gasses) the secondary fluid flow should ideally be pre heated to about 600 degrees. The slot cover also allows air to pass above the slot cover to form the primary fluid flow. This primary fluid flow passes through the fuel and is part of the primary combustion to create flames / exhaust gases. The secondary fluid flow then mixes with the primary fluid flow and a secondary combustion of the waste gases from the primary combustion occurs.

[0023] The apparatus may be formed of any material able to withstand temperatures of greater than 1000 degrees Celsius. For example, the apparatus may be formed of an aggregate material such as cement.

[0024] In one example the apparatus is formed of castable refractory. Castable refractory has a very high temperature performance. That is to say that is may be subject to high temperatures (e.g. upwards of 1000 degrees Celsius), without losing performance. A castable refractory is beneficial as it provides high performance at a relatively low cost. AL Ref: P46838WO | JTI Ref: 6775 5

[0025] A castable refractory is also often readily available across the world (e.g., such as areas in which rudimentary materials are readily available).

[0026] In one example, the castable refractory comprised a refractory cement (e.g. mortar).

[0027] In one example, there is provided a mould for forming the flow-directing apparatus, comprising:an open box element; a guide mould within the open box element for forming the one or more flow guides; and one or more bypass channel moulds for forming the one or more bypass channels. The mould provides a simple means to produce the flow-directing apparatus.

[0028] In one example, there is provided a method of manufacturing the flow-directing apparatus comprising: providing castable refractory to the mould; and setting the castable refractory within the mould to form the flow-directing apparatus.

[0029] In one example, there is provided a furnace for curing tobacco comprising: the flowdirecting apparatus; a primary combustion chamber comprising a first opening for receiving fuel and a second opening for receiving fluid flow; an air vent for receiving airflow, wherein the air vent is fluidically coupled with: the second opening of the primary combustion chamber to provide the primary fluid flow in the flow-directing apparatus; and the air inlet of the one or more bypass channels to provide the secondary fluid flow in the flow-directing apparatus.

[0030] The furnace fitted with the flow-directing apparatus provides a more efficient and sustainable means for heating a flue-cured barn. That is to say that the furnace may use upwards of 30% less fuel when compared to an equivalent furnace not including the flow-directing apparatus.

[0031] In one example, the furnace includes a secondary chamber, wherein the flow-directing apparatus is located between the primary combustion chamber and the secondary combustion chamber. The secondary chamber is a location within the furnace to in which a secondary combustion of the primary fluid flow occurs due to the presence of the secondary fluid flow. AL Ref: P46838WO | JTI Ref: 6775 6

[0032] In one example, the furnace comprises a lintel located above the flow-directing apparatus to aid with partitioning the primary combustion chamber from the second combustion chamber.

[0033] In one example, there is provided a method of heating a furnace for curing tobacco using the flow-directing apparatus according to any preceding claim, the method comprising: providing a primary fluid flow from a primary combustion chamber to a mixing region via the one or more flow guides; and providing a secondary fluid flow to the mixing region via the one or more bypass channels.

[0034] The method reduces the flow rate of the resultant mixed fluid flow, thereby improving overall heat exchange rates, whilst also enabling a secondary combustion to lead to a more efficient use of fuel.

[0035] The above referenced features may be combined together in various combinations.

[0036] Brief Description of the Drawings

[0037] Examples of the present disclosure will now be described with reference to the accompanying drawings.

[0038] Figure 1 shows a perspective view of a schematic example of a flow-directing apparatus for a furnace for curing tobacco;

[0039] Figure 2 shows a front view of a schematic example of the flow-directing apparatus shown in figure 1 for a furnace for curing tobacco;

[0040] Figure 3 shows a top view of a schematic example of the flow-directing apparatus shown in figure 1 for a furnace for curing tobacco;

[0041] Figure 4 shows a bottom view of a schematic example of the flow-directing apparatus shown in figure 1 for a furnace for curing tobacco;

[0042] Figure 5 shows a perspective view of a schematic example of a furnace for curing tobacco;

[0043] Figure 6 shows a cross-sectional view of a schematic example of the furnace for curing tobacco shown in figure 5;

[0044] Figure 7 shows an example of a mould for making a flow-directing apparatus;

[0045] Figure 8 shows a flow chart indicative of a method of manufacturing the flow-directing apparatus; AL Ref: P46838WO | JTI Ref: 6775 7

[0046] Figure 9 shows a flow chart indicative of a method of heating a furnace for curing tobacco using the flow-directing apparatus;

[0047] Figure 10 shows a schematic example of a barn include a furnace and a flue that extends through the barn;

[0048] Figure 11 shows results of a first test comparing fuel usage results in a barn using the flow-directing apparatus against a control barn not using the flow-directing apparatus; and

[0049] Figure 12 shows results of a second test comparing fuel usage results in a barn using the flow-directing apparatus against a control barn not using the flow-directing apparatus.

[0050] Detailed Description

[0051] Tobacco that is cured in a barn using a furnace and flue is referred to as flue cured tobacco or FCV. In this process, wet tobacco leaves are harvested when ripe and placed either on a string or on a stick. The string or stick is placed in the barn. Typically, approximately 80 to 120 leaves (depending on stalk position) are placed on the sting or stick.

[0052] Typically, upwards of 180 sticks or strings are then placed within the barn, in some examples approximately 220 sticks or strings are then placed within the barn. The barn may have a footprint of approximately 4m by 5m and comprise multiple tiers. Other sizes of barn are envisaged. For example, the barn may have 3 or 4 tiers that support the sticks or strings. These barns are then heated by a furnace and flue that travels through the barn. A fuel is combusted within the furnace and the exhaust gases travel through the flue to heat the internal environment of the barn. The heating of the tobacco within the barn is referred to as curing the tobacco.

[0053] Flue curing barns are used to cure tobacco leaves. The present disclosure relates to a retrofit device (i.e., the flow directing apparatus) designed to improve the operational efficiency of furnaces for curing tobacco. This retrofit device aid with providing separate flow paths within the furnace for primary and secondary fluid flows. The primary fluid flow path follows a path through the fuel and out of the retrofit device into the flue system. The secondary flow path substantially avoids the fuel and provides a source AL Ref: P46838WO | JTI Ref: 6775 8 of pre-heated air that mixes with the primary fluid flow downstream of the fuel to provide to provide a secondary combustion, which results in a more efficient and prolonged combustion process, thereby resulting in a more efficient fuel usage, whilst also reducing emissions and improving compliance with environmental standards.

[0054] Figures 1 to 4 shows a flow-directing apparatus 100 for a furnace for curing tobacco. The apparatus 100 includes one or more flow guides 102 arranged to form a primary fluid flow path. An axis X, Y, Z is provided in figures 1 to 4.

[0055] As shown in figure 1 , these flow guides 102 may comprise one or more structures, such as columns that are spaced apart from each other to define apertures 104 therebetween. The apertures 104 provide space for the primary fluid flow to flow, in use.

[0056] In one example, the flow guides 102 may include one or more end flow guides 102a arranged at or towards a side of the flow-directing apparatus 100. There may be one or more interior flow guides 102b arranged between the end flow guides 102a.

[0057] In the example shown in figure 1 , there are two end flow-guides 102a and one interior flow guide 102b. In this example, the flow guides 102 are arranged to guide the primary fluid flow path to pass through two apertures 104 formed by the flow guides 102.

[0058] However, other numbers of flow-guides 102 and apertures 104 are envisaged. For example, there may be more than one interior flow guide 102b such that more than two apertures are formed. In other examples, no interior flow guides 102b are included such that there is just a single aperture 104 formed between two end flow-guides 104a.

[0059] Given the nature of the furnace in which the flow-directing apparatus 100 may be utilised, there is potential for blockages in one or more apertures 104, for example, by part of the fuel moving downstream into the apertures. As such, providing multiple apertures 104 provides some redundancy in the system.

[0060] The flow guides 102 are shaped to restrict the fluid flow between the inlet 106 of the apparatus 100 and outlet 108 of the apparatus 100. In other words, the flow-directing apparatus 100 may be configured to throttle the primary fluid flow due to its presence thereby reducing the rate at which fluid flows across the apparatus 100 and therefore AL Ref: P46838WO | JTI Ref: 6775 9 into the flues located downstream of the apparatus 100. Restricting the rate of flow throughout the flow-directing apparatus 100 results in a restricted rate of resultant fluid flow through the subsequent flues (downstream of the apparatus 100). This increases the heat exchange efficiency as more time is provided for the exchange of heat between the hot fluid within the flues and the air outside of the flues.

[0061] In other words, the apertures 104 may each include a throat 110. The throat 110 represents a minimum dimension of the aperture 104. In other words, the throat 110 is the position at which the distance between adjacent flow guides 102 is at a minimum. The throat 110 is a key factor in restricting the primary fluid flow through the apparatus 100. In one example, the minimum distance between adjacent columns (e.g. the throat size) is between 60mm and 80mm, for example, 70mm.

[0062] In some examples, the interior flow guides 102b are shaped to have a nose with a relatively small cross-sectional area towards the inlet 106. Providing a relatively small cross-sectional area, such as a sharp corner as shown in Figure 1 or similar reduces bounce-back of fluid flow entering the inlet 106 of the flow-directing apparatus 100. The nose of the interior flow guides 102b may be a sharp angle, but may be a curved surface, in some embodiments.

[0063] As described previously, the flow-directing apparatus 100 includes an inlet 106 for receiving primary fluid flow and an outlet 108 through which the fluid flow exits the flowdirecting apparatus 100. The primary fluid flow flows substantially along the Y axis as shown in figures 1 to 4. That is, the primary fluid flow enters the flow-directing apparatus 100 in the Y axis.

[0064] In other words, the primary fluid flow is indicated by arrow A in Figure 1 and enters the flow-directing apparatus 100 at inlet 106.

[0065] The flow-directing apparatus 100 also includes a sloped base region 112 to guide the primary fluid flow. That is to say that the flow-directing apparatus 100 may include an underside wall 114 (also referred to as a bottom surface) and a sloped upper side wall 113. The underside wall 114 may be substantially planar. The upper side wall 113 is configured to be angled with respect to the underside wall 114. For example, the sloped base region 112 includes an upper side wall 113 at an oblique angle to the underside wall 114. The upper side wall 113 may be angled at between 30 to 50 degrees, for AL Ref: P46838WO | JTI Ref: 6775 10 example 40 degrees, relative to the underside wall 114. The upper side wall 113 guides the primary fluid flow such that the primary fluid flow will increase in height (i.e. move upwards in the z-axis as) as it moves along the y-axis. In some examples, the upper side wall 113 is raised from the underside wall 114 by approximately 50mm at the inlet 106 of the flow-directing apparatus 100. That is to say that there may be a step (along the z-axis) at a base of the sloped base region 112.

[0066] The sloped base region 112 may be part of the one or more flow guides 102. As with the flow guides 102, the sloped base region 112 restricts the flow of primary fluid flow from the inlet 106 to the outlet 108 of the flow-directing apparatus 100.

[0067] That is to say that the sloped base region 112 and the one or more flow guides 102 are arranged to funnel the primary air flow into a smaller area and as such, reduce the flow of primary airflow. This funnelling / restriction improves heat transfer through the flues, which are positioned downstream of the outlet 108 of the flow-directing apparatus 100. Funnelling the primary fluid flow through the apertures 104 in the flow-directing apparatus 100 slows the overall burn rate of the fuel, thereby improving combustion efficiency. In other words, the primary fluid flow from the primary combustion chamber is deliberately slowed down, allowing for more effective heat transfer to the barn. This controlled slow passage maximizes heat absorption by the surrounding structures, enhancing the overall efficiency of the system.

[0068] The upper side wall 113 may effectively reduce the size of the apertures 104 in the z- axis as the primary fluid flow travels along the y-axis. That is, the primary fluid flow is angled upwards as it travels through the apertures. The flow guides 102 in the form of columns take up space along the x-axis. That is to say that the columns guide the flow to be restricted along the x-axis (e.g. perpendicular to the direction of primary fluid flow). In some examples, the top of the columns extend beyond the top of the sloped base region 112.

[0069] In one example, the flow guides are integrally formed with the apparatus 100.

[0070] As shown in Figure 1 , the flow-directing apparatus 100 comprises one or more bypass channels 116. The one or more bypass channels 116 are arranged to form a secondary fluid flow path through the flow-directing apparatus 100. That is to say that the one or more bypass channels 116 provide a different route through the flow-directing AL Ref: P46838WO | JTI Ref: 6775 11 apparatus 100 compared with the primary airflow. The one or more bypass channels 116 are configured to extend through the flow-directing apparatus 100 from the underside wall 114 to the upper side wall of the sloped base region 112. In the example shown in Figure 1 , there are two bypass channels shown, but a different number may be used in practice.

[0071] In some examples, an inlet of the one or more bypass channels 116 is located in the underside wall 114 and an outlet 118 of the one or more bypass channels 116 is located in the sloped base region 112. In some examples, the one or more bypass channels 116 are substantially cylindrical (i.e. , tube-shaped). The one or more bypass channels 116 may extend from the underside wall 114 and to the upper side wall of the sloped base region 112 in a direction that is substantially perpendicular to the underside wall 114. In the examples shown in figures 1 to 4, the bypass channels extend along the z- axis.

[0072] The outlet 118 of the one or more bypass channels 116 is arranged downstream of the aperture 104 defined by the flow-guides 102. In this context, as fluid moves downstream as it travels substantially along with the y-axis.

[0073] The outlet 118 of the one or more bypass channels 116 is positioned such that secondary fluid flow from the one or more bypass channels 116 mixes with the primary fluid flow that passes through the apertures 104 in a mixing region 120. The mixing region 120 is the name given to the region in which the primary fluid flow and the secondary fluid flow mix together. The mixing region 120 may be defined by part of the apparatus 100 (e.g. by the sloped base region 112 and above the outlet 118 of the one or more bypass channels 116). In some examples, the mixing region 120 is bound by a ceiling 160, but this is not always the case as the primary fluid flow and the secondary fluid flow will mix close to the outlet 118 of the one or more bypass channels.

[0074] The flow guides 102 direct the primary fluid flow to mix with the secondary fluid from the outlet 118 of the one or more bypass channels 116, triggering a secondary combustion process. In some examples, the secondary combustion process occurs at approximately 600 degrees Celsius.

[0075] The mixed fluid flow leaves the flow-directing apparatus 100 via the outlet 108 in the direction indicated by arrow B in figure 1. AL Ref: P46838WO | JTI Ref: 6775 12

[0076] The primary fluid flow relates to fluid flow received from the primary combustion chamber that is guided to the mixing region 120. The primary fluid flow includes exhaust or waste gases from the primary combustion chamber. As such, providing a source of secondary fluid flow, which may comprise air flow, to mix with the exhaust or waste gases will result in a secondary combustion. This secondary combustion creates more thermal energy from the furnace, thereby improving the performance. The secondary combustion process effectively ignites and utilizes waste gases that would typically be lost, enhancing heat output and efficiency without additional fuel consumption.

[0077] Figure 2 shows a front view of the flow-directing apparatus 100. The sloped base region 112 is shown in Figure 2.

[0078] Figure 3 shows a top view of the flow-directing apparatus 100. The arrow A shows direction of primary fluid flow into the flow-directing apparatus 100 and the arrow B shows the direction of mixed primary and secondary fluid flow out of the flow-directing apparatus. As shown in Figure 2, the flow guides 102 may be arranged such that the apertures 104 taper inwards from the inlet 106 to the throat 110. Downstream of the throat, the apertures 104 may open up to a larger size again. That is to say that the throat 110 may be the smallest size of the aperture 104 and then the space for the primary fluid flow opens up again after the throat.

[0079] Figure 3 shows the mixing region 120 in which the primary fluid flow and the secondary fluid flow will mix together. Mixing the primary fluid flow and secondary fluid flow together this the mixing region increases swirling between the two flows and leads to secondary combustion of the flows. The mixing region 120 is positioned above the sloped base region 112 where the primary fluid flow and the secondary fluid flow mix. The mixing region 120 may be considered to be part of the apparatus 100 as it is defined by the shape of the apparatus 100 (e.g. as shown in figures 3 and 6). In one example, the mixing region 120 may be part of the furnace including the apparatus.

[0080] Figure 4 shows a bottom view of the flow-directing apparatus 100. Figure 4 shows the underside wall 114 of the flow-directing apparatus 100 and the inlets 122 of the bypass channels 116. AL Ref: P46838WO | JTI Ref: 6775 13

[0081] In the examples shown in figures 1 to 4, the flow guides 102 in the form of columns extend up from upper side wall 113. The columns and sloped base region may be integrally formed with each other, but the columns are only connected to one another via the sloped base region. That is to say that the columns extend substantially along the Z direction. In one example, the columns extend upwards to have a maximum height (e.g. height from the lowest region of the upper side wall from which it is connected) of between 180mm and 240mm (along the z-axis). In some examples, the overall height of the flow-directing apparatus 100 (along the z-axis) is between 250mm and 310mm and the width (along the x-axis) may be between 400mm and 460mm. The depth (along the y-axis) may be between 220mm and 280mm. At the inlet 106, the apertures 104 may be approximately 175mm (along the x-axis) and then taper in size to the throat 110, which is sized at approximately 70mm. The apertures 104 may taper in a substantially linear arrangement from the inlet to the throat 110 (that is, the columns may have straight walls to define the apertures 104 upstream of the throat 110. In contrast, the columns be curved downstream of the throat 110. That is to say that the apertures may open up rapidly immediately downstream of the throat 110 and then curve as shown in figure 3.

[0082] In one example, the bypass channels are spaced apart by approximately 140mm to 160mm.

[0083] The columns may have a flat upper surface so as to support a lintel or other structure above it. Further, the sides of the flow-directing apparatus 100 may also be substantially flat so that the flow-directing apparatus 100 may be dropped within a rectangular shaped void, in practice.

[0084] The flow-directing apparatus 100 may be a retrofit device. That is to say that existing furnaces may be modified to include the flow-directing apparatus 100. The retrofit or “drop-in” device means that local builders or farmers are able to easily install the device within existing furnaces without needing to significantly change the overall structure of the furnace. That is to say that the flow-directing apparatus 100 may be easily retrofitted within existing furnace infrastructures, minimizing disruptions and costs, and eliminating the need for costly furnace replacements or major upgrades.

[0085] Figure 5 shows an example of a furnace 150 including the flow-directing apparatus (not shown in Figure 5). AL Ref: P46838WO | JTI Ref: 6775 14

[0086] The furnace 150 includes a primary combustion chamber 152. The primary combustion chamber 152 is the part of the furnace 150 that includes the fuel (not shown) and in which the fuel is ignited. The fuel may be inserted into the primary combustion chamber 152 via a first opening 154. The first opening 154 should be adequately sized to receive the fuel, such as wood. The first opening may include a door or other mechanism for closing the first opening after the fuel has been inserted so as to prevent significant additional fluid flow into the primary combustion chamber 152 after the door has been closed.

[0087] The primary combustion chamber 152 also includes a second opening 156 (shown in figure 6) for permitting fluid flow into the primary combustion chamber 152. The second opening may be positioned on an underside of the primary combustion chamber 152. In one example, the second opening if formed as a slot that extends along a substantial length of an underside of the primary combustion chamber 152. The slot may be arranged such that it substantially retains the fuel above the slot in us, but also permits fluid flow into the primary combustion chamber 152. In one example, the second opening is formed as a “v-slot” formed by bricks or other components.

[0088] As shown in figures 5 and 6, an air vent 158 is present in the furnace 150 to allow airflow to flow into the furnace 150. The airflow that flows into the furnace 150 may be ambient air that has the atmospheric conditions with the pressure / temperature of air from outside the barn. The air vent 158 permits fluid to flow to the second opening 156 of the primary combustion chamber 152. In one example, the air vent 158 is arranged on a same face as the primary opening 152. As described above, the primary opening 152 may be selectively opened and closed, but the air vent 158 is designed to be kept open. In one example, the air vent 158 enables air to flow under the primary combustion chamber 152 and then passes up through the second opening 156 into the primary combustion chamber 152. That is to say that the air vent 158 is fluidically coupled with the second opening 156 to provide the primary fluid flow into the flow-directing apparatus 100.

[0089] Figure 6 shows a cross-sectional perspective view through the middle of the furnace 150. The flow-directing apparatus 100 may be supported by supports (not shown) at either side under the underside wall 114, but the inlets of the bypass channels should be open to permit airflow into the bypass channels 116. AL Ref: P46838WO | JTI Ref: 6775 15

[0090] The primary fluid flow is indicated by arrow C and the secondary fluid flow is indicated by arrow D. Both the primary and secondary fluid flows enter the furnace 150 via the air vent 158. The primary fluid flow travels through the second opening 156 in the primary combustion chamber 152 where the fuel may be located, if present. The primary fluid flow then enters the flow-directing apparatus 100 via the inlet 106 and is guided by the flow guides 102 to the mixing region 120.

[0091] As mentioned above, the secondary fluid flow also enters the furnace 150 via the air vent 158. The secondary fluid flow travels to an underside wall 114 of the flow-directing apparatus 100. The secondary fluid flow then travels into the inlet 122 of the bypass channels 116 and through the flow-directing apparatus 100. The secondary fluid flow is heated as it travels through the bypass channels 116 due the fact that the flowdirecting apparatus 100 will be heated due to the proximity to the primary combustion process. That is to say that the secondary fluid flow is pre-heated before entering the mixing region 120, which aids the secondary combustion. In one example, the secondary fluid flow is heated to a temperature of at least 500 degrees Celsius as it travels through the bypass channels 116. In one example, the secondary fluid flow is heated to a temperature of approximately 600 degrees Celsius as it travels through the bypass channels 116.

[0092] The secondary fluid flow then enters the mixing region 120 and mixes with the primary fluid flow. The combined fluid flow then exits the flow-directing apparatus 100 and enters a secondary combustion chamber 160 located downstream of the flow-directing apparatus 100. Supplemental combustion of the combined fluid flow takes place in the mixing region 120 and the secondary combustion chamber 160 due to the injection of heated secondary fluid flow at this location.

[0093] The combined fluid flow then exits the furnace 150 and flows into the flue system located downstream of the furnace 150. In other words, the flow-directing apparatus 100 is located between the primary combustion chamber 152 and the secondary combustion chamber 160.

[0094] The furnace 150 includes a ceiling 166 to enclose the primary combustion chamber 152, the flow-directing apparatus 100 and the secondary combustion chamber 160. That is to say that the ceiling 166 covers the top of these elements and may define the shape of the primary combustion chamber 152 and the secondary combustion chamber AL Ref: P46838WO | JTI Ref: 6775 16

[0095] 160. In one example, the furnace 150 includes a lintel 162 that is configured to abut a top of the flow-directing apparatus 100. The lintel 162 aids to separate the primary combustion chamber 152 and the secondary combustion chamber 160.

[0096] The flow-directing apparatus 100 may also include a slot cover 164, as shown in figure 6. The slot cover 164 is configured to engage with the second opening 156 of the primary combustion chamber 152. In some examples, the slot cover 164 is configured to extend into the primary combustion chamber 152 and to rest on part of the second opening 156 of the primary combustion chamber 152. That is to say that when the slot cover 164 aids to distinguish between the primary fluid flow A and the secondary fluid flow B. The primary fluid flow is configured to flow above the slot cover 164 and the secondary fluid flow B flows under the slot cover 164. The slot cover 164 may be substantially triangular shaped so as to sit within a “v-shaped” structure of the second opening 156 of the primary combustion chamber 154. The slot cover 164 may only be configured to cover a part of the second opening 156 such that the primary fluid flow A still travels thought the second opening 156 into the primary combustion chamber 152. The slot 164 cover may comprise a steel plate. For example, the slot cover 164 may be a 4mm thick plate or a 6mm plate.

[0097] The provision of the flow-directing apparatus 100 within the furnace 150 creates a means for air (from the secondary fluid flow) to mix with waste gases / components of the primary fluid flow that have already been used in primary combustion. This leads to a secondary combustion zone which improves the efficiency of the process. The inventors have found that providing the flow-directing apparatus 100 as discussed above leads to a significant reduction in the amount of fuel required to achieve the same heating results. In one example, the inventors have found that the provision of the secondary combustion leads to a reduction in the amount of wood required in the region of 30 to 35% (as indicated in Figures 11 and 12). The secondary combustion process that occurs due to the mixing of preheated secondary fluid and primary fluid flow following combustion substantially increases the energy yield from the same amount of fuel. This not only enhances the furnace’s overall efficiency but also boosts the heat output without additional fuel consumption. In the example of the fuel comprising wood, improving the efficiency of fuel usage significantly reduces the need for this natural resource, aiding in forest conservation and management. A reduction in wood fuel consumption has direct, proportional impact not only to the tobacco carbon footprint, AL Ref: P46838WO | JTI Ref: 6775 17 but also social and environmental benefits such as improved leaf yield and quality and reduced risk of land conversion and deforestation.

[0098] The flow-directing apparatus 100 effectively reduces the emission of carbon monoxide and other harmful gases, converting them into usable heat.

[0099] The flow-directing apparatus 100 has a positive environmental impact in that there is a reduction in CO2 emissions through decreased fuel consumption (e.g. decreased wood consumption).

[0100] Further, there is an enhanced combustion process to utilize waste gases within the primary fluid flow, notably carbon monoxide, as an additional fuel source, further reducing harmful emissions.

[0101] In one example, the flow-directing apparatus 100 is formed of an aggregate material, such as castable refractory. A castable refractory is dry powder product that is mixed with water which then creates a hard refractory product upon drying. It is plastic until it goes hard so can be moulded to complex shapes.

[0102] The castable refractory may comprise a castable refractory. In some examples, the castable refractory may comprise a ceramic material. For example, the castable refractory may comprise silicon carbide. In one example, the castable refractory may be comprise a high temperature metal such as Inconel.

[0103] The flow-directing apparatus 100 may be configured to withstand temperatures of upwards of 1000 degrees Celsius. In some examples, the flow-directing apparatus 100 may be configured to withstand temperatures of upwards of 1400 degrees Celsius, or even 1750 degrees Celsius.

[0104] In one example, the castable refractory may be formed of high-quality refractory cement. The refractory cement may be at least a 1400C rated cement. That is to say that the refractory cement is designed to withstand temperature of 1400 degrees Celsius, in some examples, the refractory cement may be a 1750C rated cement. Refractory cement and the other materials mentioned are able to withstand high temperatures and its durability under continuous operational stress. Materials that melt AL Ref: P46838WO | JTI Ref: 6775 18 when subject to temperatures of upwards of 1000 degrees Celsius would not be suitable.

[0105] Figure 7 shows an example of a mould 200 that may be used to make the flow-directing apparatus 100. The mould includes an open box element 202. The open box element 202 may be substantially rectangular shaped in profile. It may have an open top to enable the castable refractory to be poured into the mould 200.

[0106] Inside of the mould 200, there may be a guide mould 204 within the open box element 202 for forming the one or more flow guides 102. The guide mould 204 may comprise an angled section which is inversely shaped to the one or more flow guides 102 shown in figure 1. In other words, there may be a void where the one or more flow guide 102 is intended to be formed and a material where the apertures 104 are within the flowdirecting apparatus 100. The example of the mould 200 shown in figure 7 is configured to form the flow-directing apparatus 100 shown in figure 1 from material that sets within the mould 200.

[0107] The mould 200 also includes one or more bypass channel moulds 204 for forming the one or more bypass channels 116. In use, the castable refractory is poured into the mould 200 to set. Once set, the flow-directing apparatus 100 may be removed from the mould 200 (or the mould 200 may be removed from the flow-directing apparatus 100).

[0108] Figure 8 shows a flow-chart representing a method of manufacturing the flow-directing apparatus 100. At step 300, castable refractory is provided to the mould 200. For example, castable refractory may be poured into the top of the mould 200 in a slurry state. In step 302, the castable refractory sets within the mould 200 to form the flowdirecting apparatus 100.

[0109] Figure 9 shows a method of heating a furnace 150 for curing tobacco using the flowdirecting apparatus 100. At step 400, a primary fluid flow is provided from the primary combustion chamber 152 to a mixing region 160 via the one or more flow guides 102. That is to say that the primary fluid flow pass from the primary combustion chamber 152 into the apertures 104 of the flow-directing apparatus 100 and then mixes with the secondary fluid flow in the mixing region 160 and passes into the secondary combustion chamber 160. At step 402, a secondary fluid flow is provided to the mixing region via AL Ref: P46838WO | JTI Ref: 6775 19 the one or more bypass channels 116. The primary fluid flow and the secondary fluid flow may be provided simultaneously.

[0110] Figure 10 shows a schematic example of a barn 500 include a furnace 150 and a flue 502 that extends through the barn. As shown in the example shown in figure 10, the furnace 150 is fluidically coupled with the flue 502. That is to say that the exhaust from the furnace 150 (in the form of the combined primary and secondary fluid flows) passes into the flue 502. The combined primary and secondary fluid flows then travels through the barn 502 in the flues 502. The heat from the combined flow is then exchanged with the environment in the barn to heat any tobacco leaves within the barn. The combined flow then passes out of the barn via an exhaust 504. As a result of the more efficient heat conversion and secondary combustion, the temperature of the fluid leaving the flue vias the exhaust is significantly reduced compared to that of the standard furnace. This reduction indicates a more efficient utilization of the energy generated within the furnace 150.

[0111] The inventors have found that providing the flow-directing apparatus 100 within the furnace 150 reduces the fuel gas emissions below 20 ppm at peak operational temperatures.

[0112] To install the flow-directing apparatus 100, an existing furnace 150 is opened above a region of the furnace 150 referred to as an ash pit. The ash pit is typically towards a downstream end of the primary combustion chamber 152. The flow-directing apparatus 100 is then placed in position on supports. A region of the underside wall 114 of the flow-directing apparatus 100 that includes the inlet of the bypass channels 122 is exposed to allow secondary airflow to flow from the air vent into the bypass channels 116. If present, the slot cover 164 is placed to cover a region of the second opening 156 of the primary combustion chamber 152. A lintel is then installed 162 above the flow directing apparatus 100 and an arch of the furnace is reconstructed above the lintel 162 / flow directing apparatus 100 to reform the furnace 150.

[0113] The flow-directing apparatus 100 is positioned such that the exhaust gases from the primary combustion chamber 152 (in the form of the first fluid flow) passes into the apertures 104 of the flow-directing structure 100. In some examples, the flow rate of the primary fluid flow is restricted due to the limited size of the apertures 104. This reduction in flow rate also results in the combined primary and second fluid flowing into AL Ref: P46838WO | JTI Ref: 6775 20 the flue at a slower rate, thereby, allowing for more effective heat transfer into the barn. This controlled slow passage maximises heat absorption by the surrounding structures, enhancing the overall efficiency of the furnace 150.

[0114] Figure 11 shows the results from a first test utilising the flow-directing apparatus 100 in a furnace 150. A flow-directing apparatus 100 was installed in a furnace in barn 8. A control barn 5 was also used in the test. Both barns were heated to the same temperatures for the same amount of time and the overall usage of fuel (in the form of wood) was compared. The results indicated that the barn utilising the flow-directing apparatus required 30% less fuel to achieve the same temperatures over the same time period.

[0115] Figure 12 shows the results of a second test utilising the flow-directing apparatus 100 in a furnace. In this case, barn 7 utilised a flow-directing apparatus 100 and the results were compared against barn 1 that didn’t include the flow-directing apparatus. In this case, barn 7 required 33% less fuel to achieve the same heating profile.

[0116] All barns used were standard flue-cured barns and had an internal footprint of approximately 4m x 5m. The barns each had 3 tiers (levels of tobacco).

[0117] Although preferred embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims, and as described above.

Claims

AL Ref: P46838WO | JTI Ref: 6775 21CLAIMS1. A flow-directing apparatus for a furnace for curing tobacco, the flow-directing apparatus comprising: one or more flow guides arranged to form a primary fluid flow path to guide a primary fluid flow to a mixing region; and one or more bypass channels arranged to form a secondary fluid flow path for receiving a secondary fluid flow from an inlet, wherein the secondary fluid flow path bypasses at least part of the primary fluid flow path, wherein an outlet of the one or more bypass channels is arranged to feed into the mixing region to cause the primary fluid flow and the secondary fluid flow to mix.

2. The flow-directing apparatus of claim 1 , wherein the one or more flow guides comprises one or more columns.

3. The flow-directing apparatus of claim 2, wherein the one or more columns define one or more apertures between adjacent columns of the one or more columns, wherein each aperture comprises a throat to restrict the primary fluid flow.

4. The flow-directing apparatus of claim 3, wherein the outlet of the bypass channels is located downstream of the throat in relation to the primary fluid flow.

5. The flow-directing apparatus according to any one of the preceding claims, wherein the one or more flow guides comprises a sloped base region to guide the primary fluid flow.

6. The flow-directing apparatus according to claim 5, wherein the outlet of the one or more bypass channels is defined, at least in part, by the sloped base region to provide the secondary fluid flow to the mixing region.

7. The flow-directing apparatus according to claim 6, wherein the one or more bypass channels are integrally formed with the base region and extend from the inlet located in an underside wall of the base region to an upper wall of the sloped base region.AL Ref: P46838WO | JTI Ref: 6775 228. The flow-directing apparatus according to any one of claims 5, 6 or 7, comprising a slot cover configured to engage with a sloped recess of a primary combustion chamber, the slot cover arranged to abut the base region of the flow-directing apparatus.

9. The flow-directing apparatus according to any one of the preceding claims, wherein the apparatus is formed of castable refractory.

10. A mould for forming the flow-directing apparatus according to any one of the preceding claims, comprising: an open box element; a guide mould within the open box element for forming the one or more flow guides; and one or more bypass channel moulds for forming the one or more bypass channels.

11. A method of manufacturing the flow-directing apparatus according to any one of the preceding comprising: providing castable refractory to the mould according to claim 10; and setting the castable refractory within the mould to form the flow-directing apparatus.

12. A furnace for curing tobacco comprising: the flow-directing apparatus of any one of claims 1 to 9; a primary combustion chamber comprising a first opening for receiving fuel and a second opening for receiving fluid flow; an air vent for receiving airflow, wherein the air vent is fl uidical ly coupled with: the second opening of the primary combustion chamber to provide the primary fluid flow in the flow-directing apparatus; and the air inlet of the one or more bypass channels to provide the secondary fluid flow in the flow-directing apparatus.

13. The furnace for curing tobacco according to claim 12, comprising: a secondary chamber, wherein the flow-directing apparatus is located between the primary combustion chamber and the secondary combustion chamber.AL Ref: P46838WO | JTI Ref: 6775 2314. The furnace for curing tobacco according to claim 13, comprising a lintel located above the flow-directing apparatus to aid with partitioning the primary combustion chamber from the second combustion chamber.

15. A method of heating a furnace for curing tobacco using the flow-directing apparatus according to any one of claims 1 to 9, the method comprising: providing a primary fluid flow from a primary combustion chamber to a mixing region via the one or more flow guides; and providing a secondary fluid flow to the mixing region via the one or more bypass channels.

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