Patent Publication Number: US-11395504-B2

Title: Apparatus and method for conditioning tobacco

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the National Stage of International Application No. PCT/GB2016/053630, filed Nov. 22, 2016, which claims priority to and benefit of Great Britain Patent Application No. 1522277.1, filed Dec. 17, 2015, all of which are herein incorporated by reference in their entirety for all purposes. 
     FIELD 
     The present invention relates to an apparatus and method for conditioning tobacco after curing. 
     BACKGROUND 
     Once tobacco plants have been harvested the leaves are removed, separated and placed into a barn for drying and curing. After curing, the leaves are subsequently conditioned and then packed into bundles or bales for storage or transportation to industry for manufacture into products such as cigars or cigarettes. 
     The above processing of tobacco is often carried out under humid weather conditions. One benefit of the humidity is that it tends to soften the leaves, which can make them more pliant, i.e. less brittle and liable to damage, during the handling of the tobacco. Indeed, a common procedure for many producers is to spray water onto the leaves as part of the processing if they lack the desired softness. 
     On the other hand, an excess of moisture may impair the quality and conservation of the tobacco leaves. For example, an excess of moisture may result in serious damage to the final product quality including: fermentation, mould, loss of aroma and distinctive taste, and other chemical changes in the tobacco. The Brazilian Ministry of Agriculture has issued an Ordinance that recommends a moisture level of no more than approximately 17%. However, processed tobacco may end up exceeding this recommended moisture level, for example, because the tobacco has been processed in air of high relative humidity, and/or because additional water has been sprayed onto the tobacco, especially if the amount of sprayed water is high, and/or if the spraying has not been uniform. 
     SUMMARY 
     Aspects of the invention are defined in the accompanying claims. 
     According to a first aspect there is provided an apparatus for conditioning of tobacco leaves including a tobacco chamber for storing cured tobacco leaves for conditioning; and an air processing facility. The air processing facility includes a ventilation system for creating an airflow through the apparatus, a heater for adding heat to the airflow; and a humidity generator for adding moisture to the airflow. The airflow is drawn into the air processing facility, passes from the air processing facility into the tobacco chamber, and subsequently exits the apparatus. The apparatus is thus able to condition the tobacco leaves in the chamber to a desired moisture level by using the heater to add heat to the airflow if the moisture level of the tobacco leaves in the chamber is above said desired moisture level, and to add moisture to the airflow if the moisture level of the tobacco leaves in the chamber is below said desired moisture level. 
     According to a second aspect there is provided a method for conditioning of tobacco leaves including the steps of: introducing tobacco leaves to a tobacco chamber; using a ventilation system to draw air into an air processing facility and pass the air from the air processing facility through the tobacco chamber; heating the airflow if the moisture level of the tobacco leaves in the chamber is above a desired moisture level and using a humidity generator to add moisture to the airflow if the moisture level of the tobacco leaves in the chamber is below the desired moisture level. 
     The present disclosure helps to control accurately the moisture content of tobacco during conditioning, which is generally performed after curing but before baling, thereby avoiding a situation where, on the one hand, the tobacco which has been dried is overly brittle, resulting in the tobacco being very difficult to handle and bale for transportation, or on the other hand, the tobacco retains too much moisture, and therefore is susceptible to problems such as mould or fermentation. 
    
    
     
       DESCRIPTION OF DRAWINGS 
       The present teachings will now be described by way of example only with reference to the following figures in which like parts are depicted by like reference numerals: 
         FIG. 1  is a side view of an apparatus for conditioning tobacco in accordance with some embodiments of the invention; 
         FIG. 2  is an end view of the apparatus of  FIG. 1 . 
     
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description of the specific embodiments are not intended to limit the invention to the particular forms disclosed. On the contrary, the invention covers all modifications, equivalents and alternatives falling within the scope of the present invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a side view of an apparatus  100  for conditioning tobacco after the tobacco has been cured, but before the tobacco has been formed into bales for storage. The conditioning procedure typically last for about one day (24 hours), but may vary, e.g. from a few hours to a few days (or any suitable value according to the particular circumstances). The apparatus  100  is formed of a tobacco chamber  20  and an air processing facility  30 . The air processing facility (or chamber)  30  is provided adjacent to the tobacco chamber  20  such that the tobacco chamber  20  and the air processing chamber  30  share (i.e. are separated by) a wall  26 . Typically the apparatus  100  is formed as a barn or similar structure. The air processing chamber  30  may then be formed, for example, at one end of the barn, with an intervening wall inserted to separate the air processing chamber  30  from the tobacco chamber  20 . Another possibility is that the tobacco chamber  20  occupies substantially all of the interior of the barn, and the air processing chamber  30  is formed in a structure immediately adjacent to (and interconnected with) the barn. In other words, the air processing chamber  30  may be part of the barn itself, or may, in effect, represent an adjunct to the barn. 
     In one example, the tobacco chamber  20  is typically 10 m long, 2 m wide and 1.3 m high, but the skilled person will be aware of many other possible sizings. The tobacco chamber  20  is formed of a housing containing one or more racks  22  for supporting tobacco leaves  06  that have been cured. The tobacco leaves  06  may be introduced into the apparatus  100  in the form of individual (separate) tobacco leaves, bundles of tobacco leaves or whole tobacco plants, dependent upon how the previous processing has been performed. An access door may be provided in one wall of the tobacco chamber  20  to allow tobacco  06  to be introduced and removed from the tobacco chamber  20 . 
     The one or more racks  22  are positioned in a central portion of the tobacco chamber  20 , and often extend across the entire tobacco chamber  20  to provide the maximum amount of space for the tobacco  06 . Each rack  22  is typically formed of a wooden grid or mesh for supporting the tobacco  06 , the mesh being sized such that the tobacco does not fall through the holes in the mesh. In alternative examples the racks  22  may be formed of a wire mesh. 
     The ceiling or roof of the tobacco chamber  20  includes at least one outlet or vent or hole  24  for allowing air to escape out of the tobacco chamber  20 , typically into the external environment. In the example shown in  FIG. 1 , the ceiling includes a plurality of such holes  24 . It is also possible for at least some of the holes  24  to be located on the upper portions of the walls of the tobacco chamber  20 . 
     At least one air inlet is provided in the wall  26  separating the tobacco chamber  20  from the air processing chamber  30 . The one or more air inlet(s) are positioned in the wall  26  such that they are generally below the tobacco rack(s)  22 . In other words, the one or more air inlets in wall  26  open into the area between the floor and the tobacco rack(s), while the outlets  24  are provided in the ceiling above the tobacco rack(s). 
     In one example, the air processing chamber  30  is typically 2 m long, 0.6 m wide and 1.8 m high, but again the skilled person will be aware of many other possible sizings. The air processing chamber includes at least one air inlet  01  located in one wall of the air processing chamber  30 . In the illustrated example, the air inlet  01  is located near the ceiling of the air processing chamber  30 . An air outlet is provided near the base of the air processing chamber in the wall  26  adjacent to the tobacco chamber  20 . In particular, this air outlet from the air processing chamber  30  connects to the corresponding air inlet into the tobacco chamber  20 , thereby providing a connecting passage that allows air to pass through from the air processing chamber  30  into the tobacco chamber  20 . 
     A temperature sensor may be provided at the air outlet of the air processing chamber  30  in order to detect the temperature of air as it passes into the tobacco chamber  20 . 
     A ventilation system  02  is provided in the air processing chamber  30  to draw air into the air processing chamber  30  through air inlet  01  and to expel the air from the air processing chamber  30  into the tobacco chamber  20  via the air outlet in the dividing wall  26 . The ventilation system  02  typically includes an electrical engine or motor and a propeller or fan arranged to push air through the air processing chamber  30 . 
     A heater  03  is also provided in the air processing chamber  30 . As shown in  FIG. 2 , the heater includes a furnace  10  which is arranged to burn liquid petroleum gas (LPG), as supplied from LPG cylinder  08  via valve  09  (although other power sources, such as burning wood, could also be utilised). A duct  32  is connected to the furnace  10  to transport the fumes away from the furnace  10  to a chimney  07  which vents outside the air processing chamber  30 . The chimney  07  may be located on the opposite side of the air processing chamber  30  from the air inlet  01 , thereby helping to ensure that the exhaust from the chimney  07  does not contaminate the air which is flowing into the air processing chamber, and which will subsequently pass through the tobacco leaves  06 . 
     A heat exchanger  11  is located between the duct  32  and the chimney  07 . This heat exchanger comprises multiple U-shaped pipes which are connected in parallel to receive heated air and exhaust gases from the furnace  10  via duct  32 . These heated gases then pass along one leg-of a U-shaped pipe before returning back to the chimney  07  along the other leg of the U-shaped pipe. By having multiple such pipes, the surface area of the heat exchanger  11  is enlarged in order to provide increased heat transfer from the heated gases produced by the furnace (and flowing in the heat exchanger pipes) to the airflow that passes the heat exchanger en route from the air inlet  01  to the air outlet into the tobacco chamber  20 . 
     The air processing chamber  30  also includes a humidity generator  04 , which is linked via a connecting pipe  34  to a water reservoir  13  and a submersion pump  12 . The water reservoir  13  is provided as a source of water for providing humidity (moisture) to the tobacco leaves  06 . In some implementations, the water reservoir  13  may be provided inside the air processing chamber  30 , in other implementations, the water reservoir may be provided outside the air processing chamber  30  (as shown in  FIG. 2 ). In one example, the water reservoir  13  is able to hold 220 litres of water. 
     A submersion pump  12  is provided in the water reservoir  13  to pump water out of the water reservoir  13 , through the connecting pipe  34 , and then to be dispersed via a nebuliser or atomizer nozzle(s) into the airflow through the air processing chamber  30 . In other words, the atomizer nozzle is arranged to release atomized water into the air processing chamber  30  for supply into the tobacco chamber  20 . 
     In operation, air is drawn into the air processing chamber  30  through the inlet  01  by the ventilation system  02 . The ventilation then creates an airflow which passes through the air processing chamber  30  and dividing wall  26  into the lower portions of the tobacco chamber  20 . In passing through the air processing chamber  30 , the airflow passes both the heater  03 , in particular the heat exchanger  11 , and the humidity generator  04 . As described in more detail below, the apparatus  100  controls the heater  03  and the humidity generator  04  to add heat and/or humidity respectively into the airflow. For example, the atomiser nozzle of the humidity generator  04  may introduce water particles into the airflow. 
     The airflow, with the added heat and/or moisture as appropriate, then passes out of the air processing chamber  30  into the tobacco chamber  20  through the connecting passage in the dividing wall  26 . The air enters the tobacco chamber  20  below the one or more racks  22  and passes up through the holes in the rack(s) to the outlets  24  in the ceiling of the tobacco chamber  20 . Note that this air therefore does not circulate within the apparatus  100 , or within the tobacco chamber  20  or air processing chamber  30 , but rather just makes a single pass through the apparatus  100 , passing firstly through the air processing chamber  30  and then through the tobacco chamber  20  before exiting the apparatus  100 . 
     As the air passes over the tobacco leaves  06 , the tobacco leaves may be heated and/or moistened as appropriate (depending on the moisture and temperature of the air). In particular, if the airflow has added moisture, this will tend to increase the moisture level of the dried tobacco, hence making it easier to handle. Conversely, if the airflow is heated, this will tend to decrease the moisture level of the tobacco (by evaporating moisture from the tobacco). 
     The apparatus  100  is therefore able to maintain the tobacco leaves at a desired level of moisture (e.g. approximately 17%) by heating the airflow into the tobacco chamber  20  if the current moisture level of the tobacco leaves  06  is too high, for example when the tobacco moisture level exceeds 18%. Alternatively the apparatus is able to increase the moisture level of the tobacco leaves by adding moisture from the humidity generator if the current moisture level of the tobacco leaves  06  is too low. In this manner the apparatus is able to condition the cured tobacco to the optimum moisture level before it is baled and stored. 
     The assessment of the current moisture level may be made by a skilled human operator, who may then set the heater and the humidity generator to introduce heat or moisture into the airflow accordingly. Alternatively, some or all of this measurement and control procedure may be automated. For example, the tobacco chamber  20  may be provided with one or more humidity sensors (not shown in  FIGS. 1 and 2 ) for measuring the moisture content of the tobacco leaves  06 . An automated control system can then send appropriate command signals to actuate the heater  03  and/or the humidity generator  04  to introduce heat or moisture as appropriate, based on the readings from the one or more humidity sensors. Alternatively or additionally, a temperature sensor (not shown in  FIG. 1 or 2 ) for measuring the temperature of air is provided at the inlet to the tobacco chamber  20 . A controller can then send appropriate command signals to the heater  03  to increase or decrease the amount of heat introduced into the air as appropriate based on the readings of the temperature sensor (and/or humidity sensor  04  if present). The process is terminated when the tobacco leaves are considered to be at the desired moisture level. 
     By keeping the air at a desired moisture level between curing and baling, the apparatus  100  therefore conditions the tobacco leaves to help optimise the quality of the tobacco. In particular, the moisture level can be maintained at a level which is low enough to avoid problems such as fermentation or mould, but which is still high enough for the leaves to retain an appropriate degree of softness for ease of handling. Furthermore, by controlling the moisture level to a desired (e.g. standardised) amount, the tobacco which is input to the baling process is more consistent and predictable in terms of quality, softness, etc, which can assist in developing a more efficient and reliable baling process. 
     In conclusion, in order to address various issues and advance the art, this disclosure shows by way of illustration various embodiments in which the claimed invention(s) may be practiced. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and to teach the claimed invention(s). It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope of the claims. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc other than those specifically described herein. The disclosure may include other inventions not presently claimed, but which may be claimed in future.