PT595616E - PROCESSES FOR ADJUSTING THE HUMIDITY CONTENT OF ORGANIC MATERIALS - Google Patents

Abstract

A process for reordering tobacco, which results in no significant decrease in equilibrium tobacco CV or significant tobacco degradation, is provided. Tobacco to be reordered is contacted with an air stream having a relative humidity near the equilibrium conditions of the tobacco. As the ov content of the tobacco increases, the relative humidity of the air stream contacting the tobacco is increased to affect reordering of the tobacco. Also provided is a process for drying tobacco, which results in no significant change in equilibrium tobacco CV or significant tobacco degradation. Tobacco to be dried is contacted with an air stream having a relative humidity near or below the equilibrium conditions of the tobacco. As the OV content of the tobacco decreases, the relative humidity of the air stream contacting the tobacco is decreased to affect drying of the tobacco. It has been found that tobacco can be reordered or dried successfully in a continuous manner using a self-stacking spiral conveyor. <IMAGE>

Description

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DESCRIPTION

The present invention relates to a process for reconditioning, i.e., for increasing the moisture content and for drying tobacco or other hygroscopic organic materials such as pharmaceuticals and agricultural products, including fruits, vegetables, cereals, coffee and tea, without any limitation whatsoever. More particularly, the present invention relates to the use of controlled humidity air to moisten or dry these products.

In this art, it has long been desired to regulate the moisture content of various organic materials, including tobacco. For example, the moisture content of tobacco that has been industrially processed into a useful product is changed several times. Each step of industrial transformation, eg removal of stems, cutting, mixing of components, addition of aromas, expansion and manufacture of cigarettes, requires certain optimum levels of humidity which must be carefully controlled to ensure superior tobacco and other products hygroscopic high quality organic. Furthermore, the way in which the moisture content of the tobacco is altered can have a lasting effect on the physical, chemical and subjective characteristics of the final product. Thus, the methods used to introduce modifications in the moisture content of tobacco and other organic materials are important. The refurbishing of expanded tobacco is a particularly demanding process. Typically, the tobacco obtained from the expansion process will have a moisture content of less than 6% and often less than 3%. With such low moisture contents, tobacco fragments easily. In addition, the expanded tobacco structure may be destroyed during the reconditioning step, i.e., the tobacco may return wholly or partially to its unexpanded state. This destruction of the tobacco structure results in a loss of its filling capacity, thereby reducing the benefit obtained with the expansion process. Various processes have been used to recondition expanded tobacco. The most common method is to subject the tobacco to a cloud of water spray while the tobacco is rotated in a rotating cylinder. Another method is to use saturated steam as the reconditioning medium. There is yet another method of blowing high humidity air through a bed of tobacco moving on a conveyor belt as described in U.S. Patent 4 178 946.

None of the above methods is completely satisfactory for use with expanded tobacco. Revolving tobacco in a cylinder with atomized water fragments fragile expanded tobacco. Direct contact with the water in the liquid state tends to cause the destruction of the expanded tobacco structure. Steam reconditioning also leads to the destruction of the expanded tobacco structure. While this may be attributed in part to the high temperatures of an environment where there is steam, exposure of the expanded tobacco to any gaseous environment in which water condensation takes place, such as in a steam environment or heavily humidified air, leads to destruction of said structure.

One method which has been used to avoid these difficulties is to place expanded dry tobacco in a chamber containing air having a desired level of humidity and to expect the tobacco to reach steady state in that chamber over a period of from 24 hours to 48 hours. The speed at which the air passes into the chamber is very low, not usually exceeding about 25 feet per minute. This process results in very little or no destruction of the expanded tobacco structure. However, the long periods required, between 24 hours and 48 hours, have limited their application only to laboratory tests.

Experiments have already been carried out to reduce the residence time required for such balancing processes, increasing the air velocity. The recommended solutions have been unsuccessful due to an inability to reproduce the invariability of the filling power observed at slow laboratory equilibrium, the size of the conveyor belts needed to transport the tobacco to respond to the long periods of residence required, the non-uniformity of the moisture content as a product exiting those conveyor belts, and also to the occurrence of fires in such units, as described in U.S. Patent 4,202,357. The use of drying as a process for regulating the moisture content during the industrial transformation of tobacco is as important as reconditioning. When the tobacco is subjected to a drying process, physical and chemical changes may occur that affect the physical and subjective quality of the product. Therefore, the method of drying tobacco is extremely important. There are two types of drying equipment that are commonly used in the tobacco industry: rotary dryers and belt dryers or conveyor belts. Pneumatic type dryers are also occasionally used. The particular dryer used is chosen depending on the desired drying operation. For example, belt driers or treadmills are commonly used for strip tobacco, while rotary driers are used for cut tobacco. For tumble drying, both rotary and belt conveyors are used.

On a belt conveyor the tobacco is spread on a perforated belt and air is passed through the belt and tobacco bed, directing the air upwards or downwards. Non-uniform drying of the tobacco often occurs due to the formation of channels in the said bed, which allow the drying air to bypass the tobacco locally. Most of the rotary dryers used in the tobacco industry are coated with steam coils and can act as indirect or direct thermal dryers depending on the 3 V Γ u

in the event that the heat is applied outside or inside the tub of the tobacco-containing drier. Moreover, these driers can work concurrently, in which case the tobacco and the air flow move in the same direction, or in countercurrent, in which case the tobacco and the air flow have opposite directions. The rotary drying has to be carefully controlled to avoid excessive drying which would lead to chemical changes as well as unnecessary fractionation of the tobacco caused by the rotational movement. In addition, if the drying occurs too quickly, an impermeable layer may form on the outer surface of the tobacco, making diffusion of the moisture inside the tobacco to the surface difficult. The formation of such a layer slows down the drying rate and causes a lack of uniformity in drying. The use of a rotary dryer or conveyor belt to dry tobacco may impose a heat treatment that may eventually lead to chemical and physical changes in tobacco. Although not always undesirable, such changes are determined by the purpose of removing tobacco water. In typical tobacco applications the need to dry the tobacco within a limited period determines a heat treatment result during the drying step, preventing optimization of the heat treatment regardless of the process parameters imposed by the drying. US-A-3 879 857 discloses an elevator conveyor belt in which tobacco is transported upwardly, depicting a spiral. The air is forced down through a central core and passes over each strand of the conveyor belt and is then evacuated to the outside such that air passing through a strand does not come into contact with the air of the other strands. US-A-4 241 515 describes a linear conveyor belt in which three cooling regimes are established, each having its own source of air. In an inlet zone, the material is loaded onto three conveyor belts, arranged one above the other, and air is passed, at a temperature of about 180 ° C, from the lower conveyor belt to the conveyor belt. higher. The lower conveyor belt extends to the second and third zones. The second zone is subdivided into three and the air passes at a temperature of 180 ° C with a path coincident with the direction of travel. In the third zone, moist air at a temperature of about 25 ° C is passed through the conveyor belt perpendicular to the direction of travel. There is provided a process for varying the moisture content of an organic material, which comprises the following steps: (a) producing a bed of organic material by depositing that organic material on a lifting conveyor having a set of rows, ( b) contacting the organic material of this bed with a stream of air having a relative humidity almost equal to or less than that of the equilibrium conditions of the organic material, passing that stream of air from spin to spinning, in a trajectory almost countercurrent to the trajectory of the bed of organic material passing from one end to the other of the conveyor belt, (c) increasing or decreasing the relative humidity of the air stream which makes contact with the organic material in said bed to increase or decrease, respectively, in moisture of the organic material, such that the relative humidity of the stream of air entering c with the organic material being maintained at a value almost equal to or less than the equilibrium conditions of the organic material until the desired moisture content in said organic material is reached, whereby one of the substances, i.e. stream of air or organic material, is progressively dehydrated, and the other of these substances, i.e. correspondingly the organic material or the stream of air, is progressively hydrated as the air stream flows out almost countercurrently with respect to the trajectory of the bed of organic material. Variants of the invention have the advantage of permitting the reconditioning or drying of tobacco or other suitable hygroscopic agricultural products, including, but not limited to, fruits, vegetables, cereals, coffee and tea, little or no fragmentation, even in the case of the fragile tobacco that comes out of the expansion process. The invention further has the advantage of allowing reconditioning of expanded tobacco with little or no loss of structure of the expanded tobacco and allows drying of tobacco or any other suitable hygroscopic organic material at a pressure approximately equal to atmospheric pressure, e.g. and at a selected temperature wherein the heat treatment imparted may be regulated during the process to an extent unattainable in conventional tobacco drying processes.

In a preferred process which forms part of the invention, changes in the moisture content of the tobacco or other suitable organic materials are influenced by contacting the tobacco with air having a carefully controlled relative humidity above or below the equilibrium relative humidity of the organic material with which this air contacts. The relative humidity of the air is continuously increased or decreased as appropriate during the industrial process in order to maintain a controlled differential between the relative humidity of the air and the equilibrium relative humidity of the organic material with which that air is in contact. Careful and continuous regulation of relative humidity allows controlling the rate of transfer of the mass of water vapor between the organic material and its surrounding environment, so that the structural changes of the tobacco are minimized. The use of relative humidity as the main control force for the transfer of water vapor mass allows the heat treatment to be regulated independently. This process can be executed batch or continuously. In addition, the process can be carried out without the use of rotating cylinders and without the consequent fragmentation that occurs with their use.

The following will now be described with examples of processes forming part of the invention and their preferred variants, with reference to the accompanying drawings in which: Figure 1 is a graph which shows the percentage variation of the relative humidity of the air (HR ) depending on the moisture content or LV of the tobacco; Figure 2 is a schematic diagram of a laboratory apparatus for reconditioning the hygroscopic organic material according to the present invention, progressively increasing the HR of the air over time; Figure 3 is a cross-sectional view of an exemplary apparatus for carrying out the present invention in a continuous manner; Figure 3a is a cross-sectional view of a portion of the spiral lift conveyor shown in Figure 3, where the air stream trajectory is observed with respect to the path described by the hygroscopic organic material; Figure 4 is a schematic diagram of an alternative apparatus suitable for carrying out the present invention in a continuous manner. Figure 5 is a block diagram illustrating the application of the present invention to a reconditioning process; and Figure 6 represents a typical HR profile of air adjacent to tobacco over time obtained during reconditioning performed in the apparatus of Figure 3. The present invention describes processes for adjusting the moisture content of tobacco or other hygroscopic organic materials for example, pharmaceuticals and agricultural products, including, but not limited to, fruits, vegetables, cereals, coffee and tea, while minimizing fragmentation, changes in physical structure or changes imposed by thermal means to the chemical composition of the tobacco to be treated. More particularly, the present invention describes the use of controlled humidity air for the purpose of reconditioning or drying tobacco or any other suitable hygroscopic organic material. The moisture content of the tobacco or any other suitable hygroscopic organic material is increased or decreased by varying continuously and continuously increasing or decreasing, as appropriate, the relative humidity of the air coming into contact with tobacco or any other hygroscopic organic material appropriate. In this way, the water vapor transfer is controlled, allowing to optimize separately other variables 7 Γ

of the process, such as temperature, air velocity and its pressure.

The two methods commonly used to characterize the physical structure of tobacco are the mass volume of the compacted cylinder (VC) and the Archimedean mass volume (VM). These measurements are particularly valuable for assessing the benefits of this tobacco reconditioning process.

Mass volume of the compacted cylinder (VC) A tobacco filler having a mass of 20 g in the case of a non-expanded filler is introduced, or 10 g in the case of an expanded filler in a cylinder of a 6 cm diameter, model no. DD-60, designed by Heinr. Borgwaldt Company, Heinr. Borwaldt GmbH, Schnackenburgallee No. 15, Postfack 54 07 02, 2000 Hamburg 54,

Germany'. A 2-kg-inch plunger is applied over the tobacco contained in the cylinder for 30 seconds. The resulting volume of the compressed tobacco is read and divided by the mass of the tobacco sample to give a mass volume of the compacted cylinder in cm 3 / g. This experiment enables the apparent volume of a given mass of a tobacco filler to be determined. The resulting mass volume for this charge is called the mass volume of the compacted cylinder. This experiment is carried out in a standard environment at a temperature of 24 ° C (75 ° F) and a 60% RH; Conventionally, unless otherwise specified, the sample is preconditioned in this environment for 24-48 hours.

Archimedean mass volume (VM) The term "Archimedean mass volume" is the unit for measuring the volume occupied by solid objects, tobacco, using the Archimedes principle of fluid displacement. The Archimedian mass volume of an object is determined by calculating the inverse of its actual density. The mass volume thus obtained is expressed as "cm 3 / g". Suitable methods for carrying out such measurements are the method by porosity to mercury and the 8 V u method,

with helium, and there was a good correlation between the results of the two methods. If the helium pycnometric method is used, a duly weighed tobacco sample is placed, whether the tobacco is "as is", dried at 100 ° C for 3 hours, or equilibrated in a cell of a pycnometer 'Quantachrome Penta' model 2042-1 (manufactured by Quantachrome Corporation, 5 Aerial Way, Syosset, New York). The cell is then purged and pressurized with helium. The volume of helium displaced by tobacco is compared to the volume of helium needed to fill an empty cell without the sample. The volume of tobacco is determined on the basis of the fundamental principles of the ideal gas law. For the purposes of the present application, unless otherwise specified, the Archimedean mass volume was determined using the same tobacco sample that was used for the determination of the EV value ie dry tobacco after exposure for 3 hours in a circulating air oven with the temperature set at 100 ° C.

For the purposes of the foregoing description, the moisture content may be considered equivalent to the greenhouse volatiles (VE) content, since there will be no more than about 0.9% of the mass of the tobacco which consists of volatile substances other than Water. The determination of the volatile substances in the greenhouse is a simple measurement of the mass losses of tobacco after exposure for three hours in a circulating air oven with the temperature set at 100 ° C. The mass loss as a percentage of the initial mass value is the volatiles content to the greenhouse. The term "sieve test" refers to a method for measuring the distribution of fragments of a sample of a shredded charge. This test is often used as an indicator of the fractionation of fragments during the industrial transformation process. A tobacco filler having a mass of 150 ± 20 g in the case of non-expanded tobacco or 100 ± 10 g in the case of expanded tobacco is placed in an electric mixer. The mixer in question is equipped with a set of 30.5 cm

(manufactured by WS Tyler, Inc., a subsidiary company of Combustion Engineering Inc. Screening Division, Mentor, Ohio 44060), which meets the standards of the American Society of Testing Materials , ASTM). The normal sizes of the sieves for the joining trays are mesh 6, mesh 12, mesh 20 and mesh 35. The stroke distance of the apparatus is about 2.5 - 1.25 cm (1 - H inch) and the speed of rotation is 350 ± 5 rpm. The mixer shakes the tobacco for a period of 5 minutes to effect the separation of the sample into different batches of particles by size. Each batch of particles by size is weighed to thereby obtain a sample distribution by particle sizes.

Laboratory work has confirmed that experiments to recondition tobacco rapidly exposing tobacco to heavily humidified air cause VC losses. It has also been shown that CV losses occur whenever condensation or excessive humidification occurs in an expanded tobacco bed. The condensation takes place when the humid air comes in contact with the tobacco which is at a temperature lower than the dew point of the humid air. Excessive humidification may occur when there is moisture variation in a tobacco bed due to non-uniform exposure to moist air. Thus, the appropriate wet air reconditioning system must operate at a relatively low speed with good control of relative air humidity, air temperature, air flow and pressure throughout the tobacco bed. This is accomplished perfectly by gradually increasing the moisture content of moist air passing through the tobacco such that the tobacco is exposed to a stream of air which is substantially in equilibrium with the tobacco.

Referring now to Figure 1, the ABC line, which is an isotherm at 24 ° C (75 ° F) is shown for a typical clear expanded tobacco. This isotherm relates the LV of tobacco to the RH of the air that surrounds it in a state of equilibrium for a given temperature. Thus, point B indicates that at 24Â ° C (75Â ° F) and at 60% RH, 10Â ° C-1 the expanded tobacco sample will have a LV content of about 11.7% after reaching the balance. The DEF line of Figure 1 represents a typical HR profile for tobacco that has been refurbished in accordance with the present invention. The GEF line of figure 1 represents an alternative HR profile also considered satisfactory. The HF line of Figure 1 represents a typical prior art route, corresponding to laboratory reconditioning in an equilibrium chamber for very low air velocities. Line IJ of Figure 1 represents the application of the present invention to tobacco drying. Figure 1 shows that reconditioning of tobacco from an LV value of about 6.5%, wherein the tobacco would be in equilibrium with air with an RH of about 30%, until a value of VE of about 11.7%, where it would be in equilibrium with air at about 60% RH, may be carried out by exposing tobacco to air whose moisture content is increased from about 40% RH in small increments over a period of time, until a RH of about 60% is achieved instead of leaving the tobacco exposed directly to air with a 60% RH. When the procedure is performed under these slow variation conditions, the mass transfer between the air stream and the tobacco is relatively slow since the force responsible for the transfer is small, and the structure of the expanded tobacco is consequently preserved. The expanded reconditioning, without any VC losses, can also be accomplished by exposing the tobacco to air whose moisture content increases from about 40% RH by small increments over a period of about 40 minutes to about of 60 minutes, until a RH of about 62% is reached. This reduces the total time required to complete the reconditioning process without significantly modifying the expanded tobacco structure. Thus, each of the lines DEF and GEF of Figure 1 translates effective aspects of the present invention when reconditioning tobacco.

Referring still further to Figure 1, the line segment EF and line ABC are shown illustrating conditions of near equilibrium between the air stream and the tobacco. It should be noted that for a

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tobacco value of less than about 7%, the difference between the relative humidity of the air in equilibrium with the tobacco and the relative humidity of the stream of moist air used for the reconditioning can be quite large without adversely affecting the power of tobacco filler. It will also be appreciated that for LV values of tobacco ranging from about 7.5% to about 11.5%, the relative humidity of the stream of moist air used to recondition the tobacco may range from about 2% to about about 8% above the value of the relative humidity of the air in equilibrium with the tobacco, the greatest deviation from the steady state at the lowest LV value of the tobacco, without adversely affecting the filling power of the tobacco.

Using the present invention to dry tobacco, no measurable losses of tobacco VC were observed. It was found that this was also the case in cases where the relative humidity of the drying air stream was significantly lower than the relative humidity of the air in equilibrium with the air, i.e., the relative humidity of the drying air stream was below conditions. Having said this, it will be appreciated that the line IJ in figure 1 illustrates only one of the many possible routes that can be used in drying tobacco according to the present invention. The present invention may be practiced batchwise or in a continuous process. In performing a batch reconditioning process, the relative humidity of the air stream coming into contact with the tobacco is increased over a given period to provide a continuous increase in the moisture content of the tobacco. This can be carried out in a reconditioning chamber in a controlled environment such as that shown in figure 2. The tobacco to be reconditioned is placed in a bed having a height of about 5.1 cm (2 inches) in trays whose bottoms are knitted of winding within a reconditioning chamber so that a stream of controlled humidity air can pass through the tobacco in a downward direction. Chambers with volumes ranging from about 0.57 m3 to 12 μm were used in several studies. (20 cubic feet) and about 80 cubic feet (manufactured by Parameter Generation and Control, Inc., 1104 Old US 70, West, Black Mountain, N.C., 28711). The reconditioning chambers were equipped with microprocessors that allowed a progressive and controlled increase of humidity and air parameters within these chambers. Experiments were performed in which expanded dry tobacco was reconditioned from initial LV levels of 2% to final LV levels of 11.5%, gradually increasing HR from initial levels of the order of 30% to high values of the order of 52% over periods ranging from about 30 minutes to about 90 minutes, until RH levels ranging from about 59% to about 65% are reached. Air velocities ranging from about 0.25 m / s (50 ft / minute) to about 1 m / s (200 ft / minute) were used. HR and temperature measurements were checked with a Model 4A-1 'Thunder' type instrument (manufactured by Thunder Scientific Corp., 623 Wyoming, S.E., Albuquerque, New Mexico 87123). Air velocities were measured with an Alnor model 8525 thermo-anemometer (manufactured by Alnor Instruments Co., 7555 N. Linder Ave, Skokie, Illinois 60066). Experiments in which the relative humidities were being progressively increased from initial values of the order of 52% to RH values of the order of 62% over a time interval of about 40 minutes allowed to obtain a reconditioned tobacco with a retention complete comparison of the VC compared to the like refurbished tobacco in a controlled environment compartment in which air was maintained at 60% RH and at 75 ° F (24 ° C) through the tobacco at low speed during a between 24 hours and 48 hours. The progressive increase in relative humidity in this way was successful with wet air velocities of the order of 1 m / s (200 ft / min) and at temperatures ranging from about 24 ° C (75 ° F) to about of 32 ° C (90 ° F). The expanded and thus reconditioned tobacco showed minimal or no loss of CV as compared to 13

Lc, with the tobacco expanded and reconditioned in a controlled environment compartment. The present invention can be performed as a continuous process much more efficiently on a Frigoscandia type self-pivoting spiral conveyor belt machine, such as the machine shown in Figure 3. This equipment is a specially modified GCP 42 spiral refrigerator provided by " Frigoscandia Food Process Systems AB "in Helsingborg, Sweden. The tobacco to be reconditioned enters the unit 10 through the inlet opening 12 of a conveyor belt 13, will run through the unit 10 depicting a spiral geometry circuit from the bottom to the top of the spiral column 14, as shown, and leaves the tobacco outlet 11 after reconditioning. The humidified air is blown downwardly through the tobacco from the humid air inlet 15 to the bottom of the spiral column 14 through which it exits through the humid air outlet 16, flowing virtually countercurrent relative to the tobacco path, this the bulk of the humid air flow originates at the top of the column and proceeds downwardly through the rows of the tobacco bed as it travels upwards, describing the spiral path of the tobacco. conveyor belt. There is a small part of the humid air that accompanies the spiral circuit of the lift conveyor, from the top to the bottom, describing a true counter-current trajectory. These types of airflows are illustrated in Figure 3a. It has been found that this provision effectively reproduces the progressive increase of the RH obtained with the equipment of Figure 2.

Referring to Figure 3a, which is a cross-sectional view of a portion of the spiral conveyor belt 14 shown in Figure 3, the trajectory of the air flows 20 and 22 is observed with respect to the trajectory of the tobacco bed 21. Accordingly 3a, the air flows 20 and 22 develop downwardly from the top of the column. Tobacco is advanced from the bottom to the top of the unit and in Figure 3a 14

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is assumed to move from right to left as it rises carried by the spiral conveying conveyor belt 14. Most of the air flow 20, which develops almost countercurrently with respect to the tobacco path, will traverse the layer of the tobacco bed 21 and comes into contact with the bed of. tobacco at the level immediately below, while there is a small part of the air flow 22 which passes over the tobacco bed 21 in a countercurrent direction relative to the path of the tobacco bed 21. This part of the air flow 22 may pass after by the tobacco bed 21.

For correct implementation of the invention, in the case of reconditioning, it is necessary to provide a device for constantly increasing the relative humidity of the air in contact with tobacco, as the LV content of the tobacco increases. The 'Frigoscandia' self-lifting spiral conveyor belt, due to its self-lifting design, directs most of the airflow downwards through the multiple conveyor belt rows (the height of the lifting column described by the conveyor belt) that are to carry tobacco. By placing the tobacco in the lower part of the lifting conveyor belt and introducing humidified air through the top of that lifting conveyor belt, the main air flow and the moving tobacco are practically countercurrent. This almost countercurrent flow generates a continuous, natural gradient of RH in the air coming into contact with the tobacco as the air is progressively dehydrated as it passes downwardly through the tobacco strands subjected to the reconditioning process. By a balanced selection of the conveyor belt speed, the air and tobacco flow rates, and by regulating the temperature and the HR of the incoming air, it is possible to approximate conditions similar to those used in the reconditioning experiments of the laboratories treated progressively. In order to recondition expanded tobacco with a 3% LV content at approximately 150 psig (approx. 18.9 g / s), it has been found that conveyor belt speeds enabling residence times to be achieved about 40 minutes to about 80 minutes and the use of air at a temperature of about 75øF (24øC) to about 35øC (90øF), with inlet humidities comprised between about 61% and about 64% for air flow rates varying between about 1000 cubic feet per minute (PCM) and about 1.18 m 3 / s (2500 PCM), provide a complete reconditioning without significant losses of VC and without measurable fractionation of tobacco, using the modified spiral unit 'Frigoscandia GCP 42'.

During the reconditioning of the tobacco, devices for recording the relative humidity over time were tested in the 'Frigoscandia' unit, such as the model 29-03 thermo-hygrograph (manufactured by Rustrak Instruments Co. of E. Greenwich, RI). These devices demonstrated that there was a constant increase in relative humidity as they went up, transported by the spiral conveyor belt, with initial HR values ranging from about 35% to about 45% at the bottom of the conveyor belt where the tobacco is drier, up to about 62% at the top of the conveyor belt where the tobacco is most perfectly refurbished. Figure 6 is a typical curve of variation of HR versus time obtained with a 'Rustrak' type unit. The percent change in the HR of the air adjacent to the tobacco bed as a function of time is illustrated in Figure 6. Tobacco with an initial LV content of about 3% entered the reconditioning spiral unit and was in contact with air having a RH of about 43% (point A of figure 6). Figure 6 shows that as the tobacco has been advanced through the spiral reconditioning unit, the HR value of the air adjacent to the tobacco has increased from about 43% to about 62% at the outlet of the unit (point B of Figure 6) . The tobacco had an LV content of about 11% on exiting the reconditioning spiral unit. The HR of the air was regulated at the inlet of the refractory spiral unit

to obtain refurbished tobacco without significant losses of CV. Other devices can also be used to obtain HR varying air, for example the unit shown in Figure 4, to carry out the present invention continuously. Referring to Figure 4, the tobacco enters the unit through the tobacco inlet 40 through which the conveyor belt 43 passes and exits the tobacco outlet 41. The air with constantly increasing relative humidity is required to pass either up or down through the tobacco bed 42 in the set of zones 44 to reproduce the progressive increase effect imposed by the apparatus of Figure 2. The progressive increase effect can be achieved by resorting to air from a single, serpentine-shaped source from right to left in Figure 4, thus obtaining an air flow substantially countercurrent relative to the direction of movement of the tobacco. That being said, the air exiting a given zone could be the entrance air to the zone adjacent to its left.

In order to carry out the process of the present invention it is possible to treat whole cured tobacco leaves, cut or shred tobacco, either expanded or non-expanded tobacco or selected pieces of tobacco, such as stems, or reconstituted tobacco. The process may be applied to any of the types of tobacco or all of the above types of tobacco, with or without the addition of flavoring agents. In the specific case of tobacco drying, it has been found that an unpuffed cut tobacco filler can experience the drying treatment continuously, practically at room temperature, by practically countercurrent flow through the conveyor belt, self-pumping spiral modified from the Frigoscandia type, from a tobacco moisture content of about 21% LV to about 15% LV in about 1 hour. In this case, the air entered the top of the unit at a temperature of about 85øF and an RH of about 58% and left at a temperature of about 25øC (77øF) and with an RH 17 V Γ u

of about 68%. Drying was performed with little or no heat treatment of the tobacco.

Alternatively, the process of the present invention may be used to dry tobacco which is at a temperature significantly above room temperature, e.g. g. tobacco at a temperature in the range of about 200Â ° F (93Â ° C) to about 250Â ° F (121Â ° C). When drying tobacco whose temperature is within these limits, the RH value and the temperature of the drying air are adjusted to achieve the conditions convenient for carrying out the process of the present invention.

Similarly to the reconditioning of tobacco, it was found that drying was best performed in a minimum interval of time by adjusting the final moisture content of the air to a value lower than that which would be required to bring the tobacco to its final level thereby increasing the air-tobacco moisture gradient and consequently the force responsible for carrying out the drying. Unlike the reconditioning process, it is possible to maintain the final moisture content of the air stream at a much lower level than would be in equilibrium with the tobacco at the desired LV level after drying.

Experience # 1

To demonstrate the advantage of reconditioning dry and expanded tobacco, by slow addition of water, compared to reconditioning in spray-water cylinder, a sample of 20 g of a tobacco filler was placed in a sealed excercise. This sample had been impregnated with liquid carbon dioxide and expanded in an expansion tower at 288 ° C (550 ° F). The LV content of this expanded tobacco filler was 3.4%. It was estimated that approximately 1.89 g of water would be needed to increase the LV content of this sample to 11.5%. This amount of water was introduced into a small glass bottle with a rubber stopper passed through a glass tube with an inner diameter of 1/8 inch (0.318 cm). This bottle was also closed 18

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sealed in the desiccator. At the end of 9 days all the water had been adsorbed by tobacco. Tobacco was then analyzed and found to have a natural LV content of about 11.5%. The term 'natural' used herein refers to the tobacco before it has been equilibrated in an air-controlled environment reconditioning chamber with a relative humidity RH of 60% and a temperature of 24Â ° C (75Â ° F) said tobacco at low speed for a period of from 24 hours to 48 hours. This balancing process is generally used as a means to correct the tobacco to the standard state before the VC, VM and particle size measurements are made. After this equilibrium was carried out to a standard state, the refurbished tobacco in the desiccator had a VC value of about 9.5 cm 3 / g and a VM value of about 2.9 cm 2 / g and a VE value of about 11.6%. In comparison, by placing a second sample of the same tobacco directly into the equilibration chamber and reconditioning it by equilibrating under the same standard conditions, the LV equilibrium content was about 11.3% and the values of VC and of VM were respectively about 9.4 cm 3 / g and about 2.7 cm 3 / g. In a hydromediation cylinder a third sample of the expanded tobacco filler was reconditioned until a natural EV value of about 11.5% was obtained. After steady state was reached, this sample had a VC of about 8.5 cm 3 / g and a MV of about 1.9 cm 3 / g for an LV equilibrium value of about 11.6%.

As shown in Table 1, the tobacco sample that was refurbished in the desiccator by the slow addition of water showed a significant improvement in the balance between VC and VM compared to the sample that had been reconditioned by micronization of water. This sample also showed a slight improvement in VC and MV compared to the sample equilibrated directly in the equilibrium chamber. 19 TABLE 1

Sample VE (% Natural) VM (cmVg) VE (%) Balanced VC (cmVg) VM (cmVg) Tower output 3.4 3.0 11.3 9.4 2.7 Refurbished 11.5 1.8 11, 6 8.5 1.9 in cylinder Desiccator 11.5 2.7 11.6 9.5 2.9

A second set of experiments was performed using a controlled environment conditioning chamber to recondition an expanded tobacco filler. For this purpose a generator and regulator of Parameter Generation and Control (PGC) parameters were used. This camera was equipped with a 'Micro-Pro 2000' microprocessor provided by the company "Parameter Generation and Control Inc.," having served this microprocessor to regulate the progressive increase of conditions within the chamber.

Experience # 2

An approximate amount of 1.36 kg (3 pounds) of clear tobacco impregnated with liquid carbon dioxide and expanded under the same conditions as described in Experiment # 1 was used, that amount being placed in a bed having a height of about 2 inches inside a board. Said tray, which had compact sides and a bottom made of a mesh of glass, was placed inside a conditioning chamber. The sample was then reconditioned over a period of 1 hour, using air at a temperature of about 24 ° C (75 ° F) with an initial value of about 36% RH which was gradually increased until a final value of RH of about 60%. The air stream was downwardly through the tobacco bed at a rate of about 0.23 m / s (45 ft / m). This experiment was then repeated over time at 3 hour, 6 hour and 12 hour intervals. The results obtained, grouped in Table 2, indicate that the rate of reconditioning, for periods of progressive increase of humidity up to about 6 hours, does not affect the values of VC and VM of tobacco in such experimental conditions. The lower the rate of re-conditioning, the higher the VC and VM values observed. Further, the reconditioning according to the present invention results in VC values which are higher, at least about 1 cm 3 / g, and MV values which are higher, at least about 0.2 cm 3 / g, than those observed with refurbished tobacco in a hydro-cyclization cylinder. However, it has been found that most of this benefit is achieved by making said progressive increase over a period of the order of 1 hour. TABLE 2

Natural Balanced in a conditioning chamber VE (%) VM (cm3 / g) VE (%) VC (cm7g) tower outlet 3.10 3.06 11.33 9.71 hydro-cylinder 11.51 1.61 11 , 37 8.61 micronisation progressive increase 10.83 1.85 11.38 9.72 from 1 hour progressive increase 11.44 1.88 11.36 9.81 from 3 hours progressive increase 11.45 1.90 11, 30 9.88 from 6 hours progressive increase 11.41 1.97 11.27 9.89 from 12 hours Experiment # 3 A laboratory study was conducted on the influence of reconditioning speed and temperature on the values of VC and VM of tobacco. Seven experiments were performed with tobacco impregnated with carbon dioxide and expanded in an expansion tower at a temperature of about 288 ° C (about 550 ° F). The expanded tobacco was refurbished by the following methods:

(1) allowing it to reach steady state for 24 hours in a conditioning chamber at 60% RH and at 75 ° F, the air stream being passed by the tobacco at a rate of about 0.13 m / s (about 25 ft / min). (2) by spraying the tobacco with water to increase the LV content to about 7.5% and hoping it would then reach steady state at 60% RH and at 75 ° F for 24 hours hours as indicated in (1); (3) by spraying the tobacco with water to increase the LV content to about 7.5% and by final reconditioning in a micronization cylinder; (4) by spraying the tobacco with water to an LV content of about 7.5% and then using wet air having a moisture content increasing progressively from an initial value of RH of about 46% to a value end of the HR of about 60%; and (5) effecting the progressive increase of moisture with moist air, from an RH of about 46% to about RH of about 60%. The wet air reconditioning was performed within a PGC controlled environment conditioning chamber equipped with a microprocessor to regulate the progressive increase of humidity at selected time intervals. The following conditions were chosen: (1) periods of progressive increase of humidity: 30, 60 and 90 minutes; (2) air temperature: 24 ° C (75 ° F) and 35 ° C (95 ° F); (3) air velocities: upstream through the tobacco bed of about 0.23 m / s (45 ft / min) and downward through the tobacco bed of about 0.89 m / s (175 ft / min); and (4) height of the tobacco bed: 5.08 cm (2 inches). The tobacco used in all reconditioning procedures, except through the hydro-cyclization cylinder, was collected at the exit of the tower after expansion and closed in double plastic bags prior to reconditioning. As a consequence, the tobacco quenched from about 93 ° C (200 ° F), which is the temperature of the tobacco exiting the expansion tower, to room temperature, prior to reconditioning. Upon reconditioning by progressively raising the humidity to a temperature of about 35øC (95øF), the tobacco, although still in the sealed bags, was preheated sufficiently to avoid condensation on contact with the before being exposed to the conditions of progressive increase of humidity. Data for these experiments are shown in Tables 3a to 3e.

Table 3a

Balanced Natural Sample VE VM VE VC (%) (cm 7g) (%) (cm 7g) HIJK At the exit of the tower 3.43 3.02 11.31 9.04 Only through the sprayers 8.06 2.14 11, 68 8.66 Through sprayers and cylinder 11.53 1.81 11.59 8.59 Through sprayers and progressive increase over 90 minutes (RH between 46% and 60%, 24 ° C (75 ° F) 11, 27 1.87 11.51 9.01 By sprayers and progressive increase over 90 minutes (RH between 46% and 60%, 24 ° C (75 ° F) 10.96 1.98 11.36 9.48 Sample H maintained 15 minutes with a 60% RH, 24 ° C (75 ° F) 11.54 1.95 11.56 9.40 By sprayers and progressive increase over 60 minutes (RH between 46% and 62%, 35 ° C C (95 ° F) 10.37 2.38 11.28 9.85 Sample J maintained 15 minutes with νmax 11.17 2.26 11.22 9.88 a HR of 62 %, 35øC (95øF) xsc

F 23 Γ u

Natural Balanced VE VM VE VC (%) (cm Vg) (%) (cm 7c 3.01 2.58 11.34 9.23 7.51 2.13 11.39 8.87 11.86 1.59 11 , 64 8.07 10.55 1.64 11.45 8.86 11.56 1.64 11.42 8.61 10.28 1.97 11.27 8.99

Table 3b

Sample X At tower outlet S Only through sprayers C Through sprayers and cylinder F Through sprayers and progressive increase over 60 minutes (RH between 46% and 60%, 24 ° C (75 ° F) G Sample F maintained 15 minutes with a 60% RH, 24 ° C (75 ° F) progressive for 30 minutes (RH between 46% and 60%, 24 ° C (75 ° F)

Sample H maintained 15 minutes with a 11.73 RH of 60%, 24 ° C (75 ° F) 1.82 11.25 8.61 24 X Sample

Table 3c t

Β C D E F

G

H

I

J

K

L at the exit of the tower Progressive increase during 60 minutes (HR between 46% and 60%, 95 ° F) Progressive increase during 60 minutes (RH between 46% and 60%, 75 ° F) Progressive increase for 90 minutes % and 60%, 95Â ° F) Through the sprays Through the sprays and exposed directly at 60% RH, 95Â ° F for 30 minutes By sprayers and progressive increase over 60 minutes (RH between 46% and 60%, 95% ° F) Through sprayers and progressive increase over 90 minutes (RH between 46% and 60%, 95 ° F) Through sprayers and progressive increase over 60 minutes (RH between 46% and 60%, 75 ° F) and progressive increase over 90 minutes (RH between 46% and 60%, 75 ° F) Through sprayers and directly exposed at 60% RH, 75 ° F for 30 minutes Through sprayers and cylinder

Natural Balanced VE VM VE VC (%) (cm Vg) (%) (cm Vg) 1.81 2.78 11.37 9.23 10.91 1.86 11.47 8.86 10.53 2.02 11.28 9.20 10.84 1.99 11.45 8.90 5.39 2.37 11.25 8.71 10.80 1.81 11.27 8.39 10.66 1.85 11, 23 8.65 10.76 1.82 11.24 8.62 10.65 65.90 11.23 8.75 10.57 1.87 11.38 8.74 10.73 1.87 11.28 8 , 64 10.98 1.60 11.39 8.28

N.F. 75 ° F = 24 ° C 95 ° F = 35 ° C 25 χ Γ

3d board

Balanced Natural Sample. VE VM VE VC (%) (cm 7g) (%) (cm J / g) TI At tower output 2.83 3.01 11.92 9.46 T2 Directly displayed at 60% RH, 75 ° F for 30 minutes 11.24 2.27 11.77 9.08 T3 Progressive increase over 90 minutes (RH between 46% and 60%, 75 ° F) 11.08 2.24 11.83 9.29 T4 Progressive increase during 90 minutes (RH between 46% and 60%, 795 ° F) 9.77 2.39 11.85 9.43 SI Through sprayers 4.78 2.82 11.66 8.98 S2 Through sprays and exposed directly at a 60% RH, 75øF for 30 minutes 11.10 2.19 11.64 8.89 S3 By sprayers and progressive increase over 90 minutes (RH between 46% and 60%, 75øF) 10, 54 2.25 11.27 9.05 S4 Through sprays and progressive increase over 60 minutes (RH between 46% and 60%, 75 ° F) 10.56 2.22 11.73 9.03 S5 Through sprayers and progressive increase over 30 minutes (HR between 46% and 60%, 75 ° F) 9.74 2.29 11.67 9.19 C Through the sprayers and the 10.48 1, 95 11.81 8.80 cylinder

Ν.Β. 75 ° F = 24 ° C 95 ° F = 35 ° C 26 .τ Γ L ·

Table 3e

Progressive increase conditions Natural Balanced VE Speed Time Temp. (%) (%) (M / s) HR m / s variation (%) Entered at 15, 40 0, 79 11.86 5.05 Tower At the exit of the tower 3.94 2.82 11.72 9.49 At the exit of the 1st floor of 5.64 2.72 11.82 9.48 Spraying At the exit of 10.36 2.04 11.66 9.28 cylinder A 3.9 1.19 60 24 30-58 6.67 2.39 11.65 9.76 B 5.6 0.89 60 24 30-58 8.44 2 , 45 11.82 9.91 C 3.9 0.97 60 24 45-58 7.83 2.25 11.65 9.57 D 5.6 0.97 60 24 45-58 8.44 2.39 11.79 9.66 E 3.9 0.97 60 24 47-62 11.10 2.33 11.74 10.02 F 5.6 0.89 60 24 47-62 10.10 2.41 11, 59 10.08 G 3.9 0.91 60 24 30-62 8.13 2.20 11.89 9.63 H 5.6 0.89 60 24 30-62 9.41 2.41 11.79 10 , 11 I 3.9 1.02 60 24 47-62 10.21 2.15 11.76 8.98 J 3.9 0.91 60 2'4 47-64 10.18 2.13 11.94 9 , 03 K 3.9 0.91 60 24 35-64 9.07 2.23 11.90 9.51 L 3.9 0.91 60 35 35-60 8.65 2.17 12.09 8.59 M 3.9 0.91 60 35 45-60 10.11 2.39 11.92 10.02 N 5.6 0.91 60 35 45-60 10.08 2.39 11.9 3 10.02 0 3.9 1.22 60 35 47-64 10.88 2.31 11.96 9.51 P 3.9 1.22 60 35 47-64 11.30 2.33 11.95 9 , 30

The data pooled in Tables 3a to 3e show that gains can be achieved between about 0.5 cc / g and about 1 cc / g for VC values and between about 0.3 cc / g and about 0.4 cm3 / g for the MV values, thanks to the progressive increase in cooling of the cooled tobacco, ie tobacco at a temperature of about 24 ° C (75 ° F) to not more than about 35 ° C ( 95 ° F) as compared to the reconditioning, in micronisation cylinder with water, of the hot tobacco exiting the expansion tower. Concerning 27 æ u reconditioning by progressive increase of moisture, directly from the tower outlet, it was found that it was preferable to manipulate the LV content by first spraying the tobacco to increase its LV content to about of 7%, followed by reconditioning by progressive increase of humidity. No significant differences were observed in VC or MV values of refurbished tobacco by progressive increase of humidity using moist air with an initial value of RH of about 46% as compared to tobacco refurbished by progressive increase of moisture from an initial value of RH about 30%, or in refurbished tobacco by progressively increasing the humidity over a period of the order of 60 minutes or about 90 minutes. It was also found that the tobacco could be reconditioned by resorting to both downwardly directed air streams through the tobacco bed at speeds of from about 0.89 m / s (175 ft / min) to about 1.20 m / s (235 ft / min), or upstream through the tobacco bed, at a rate of up to about 0.23 m / s (45 ft / min), without any significant differences in VC or VM. In addition, it was found that progressive reconditioning made it possible to obtain equivalent or better VC and MV values as compared to refurbished tobacco by being placed directly in a conditioning chamber at 60% RH and at a temperature of 24øC F) after exiting the expansion tower. Finally, it was found that by spraying with water to increase the LV content to about 7.5% following progressive humidification with moist air, it was possible to obtain better values of VC and VM compared to the spraying process followed by final reconditioning in a hydro-cyclization cylinder.

Experience # 4

Tests were carried out to determine the effect of air flow and its velocity on entrainment, channel opening and tobacco compaction. These tests were performed using 28 (two PGC-type conditioning chambers). In either chamber the actual air flow rate was approximately 0.24 m 3 / s (500 ft 3 / m) upstream through the tobacco bed in one of the 'PGC' chambers and downstream through the tobacco bed in the other chamber. Tobacco samples having a thickness of 5.8 cm (2 inches ) into open topped trays 5 "x 5V 'and the bottoms of which were made up of meshing meshes, the sides thereof being compact and having a height of 10.16 cm (4 inches). The air was forced to pass through the samples, the unoccupied area of the shelf was capped with cardboard and all slots sealed with tape. The air velocity was varied by changing the number of containers of samples atra from which the air had to pass. The tobacco used in these tests was impregnated with carbon dioxide and expanded to a temperature of about 288 ° C (550 ° F). The tobacco had been reconditioned on the first floor by spraying with water until a LV content of about 8% immediately after expansion was obtained. The conditions inside the chambers during the tests were set at about 24 ° C (75 ° F) and for an RH of about 60%. Two apparatus were used to measure air velocities: an airflow instrumentation (LCA 6000 model, Fredericks, Maryland) and an incandescent filament anemometer (Alnor Instrument Company, Skokie, Illinois, model 8525 thermometer ). These instruments were placed directly above or below the samples to measure air velocities respectively upstream and downstream.

With the upward air stream a slight lifting of the tobacco was observed at the time the stream of air was imposed at a velocity in the order of about 0.13 m / s (26 ft / min). Small channels of passage of air were formed where tobacco could fall. As a consequence of the formation of these channels, it was found that the air flow was quite non - uniform through the bed of 29

V

I

(22 ft / min) to about 0.23 m / s (45 ft / min), the average velocity being about 0.13 m / s ( 26 ft / min). With increasing average air velocities more channels were appearing and above 0.23 m / s (45 ft / min) there was considerable entrainment and "blowing" of the tobacco, followed by a significant opening of channels in the bed.

With the downstream air current, a certain compaction was observed and the corresponding reduction of the velocity of the air through the beds for all speeds studied was observed. This is summarized in Table 4. For an initial velocity of about 0.98 m / s (192 ft / min) the height of the tobacco bed was compacted about 28% and as a consequence the velocity of air through the bed decreased to about 0.72 m / s (141 ft / min). At initial air velocities of about 0.72 m / s (141 ft / min) or less, the compaction of the tobacco bed was about half of the observed value at the rate of about 0.98 m / s (192 ft / / min) and the air flow through the tobacco bed was much less reduced.

Table 4

Effect of bed compaction on air velocity through it

Air velocity (m / s) Bed thickness (inches) Start End Variation (%) Start End Variation (%) 0,98 0,72 27 2 1,45 28 0, 82 0,73 11 2 1,65 18 0.72 co O 6 2 1.70 15 0.53 0.50 6 2 1.80 10 0.22 0.21 5 2 1.90 5

On the basis of the experiments set forth above, it has been found that it is possible to recondition expanded tobacco, preferably by performing progressive variation of humidity under the following conditions: (a) time: from about 60 minutes to about 90 minutes; (b) RH: ranging from an initial RH value of from about 30% to about 45% to a final RH value of from about 60% to about 64%. 30

(c) temperature: from about 24 ° C (75 ° F) to about 35 ° C (95 ° F); (d) air velocity: rising at speeds up to about 0.23 m / s (45 ft / min) or descending at speeds up to about 1,19 m / s (235 ft / min).

Experience # 5

A clear Burley-type tobacco mixture was passed at about 18.9 g / s (150 lb / hr), the tobacco having been previously impregnated with carbon dioxide in accordance with the process described in the application for copending patent commonly assigned to Cho et al., SN 0771717 067, and also expanded samples as described in the foregoing examples, through a cooling conveyor belt to reduce the respective temperatures to about 93 ° C ( 200Â ° F) to about 29Â ° C (85Â ° F), then fed to a modified Frigoscandia GCP 42 self-elevating spiral unit. The circuit described by the tobacco in the spiral unit has developed from the bottom to the top. The air flow traveled through the unit from the top to the bottom, thus producing a countercurrent flow between tobacco and air. These arrangements allowed for the progressive reconditioning of tobacco as a result of the continuous dehydration of air by tobacco. The tobacco was introduced in the process with an LV content of about 3% and left with an LV content of about 11%. The value of the balanced VC of the material used at the inlet was about 10.53 cm 3 / g, whereas the value of the balanced VC of the reconditioned material was about 10.46 cm 3 / g, indicating that there were no losses significant of the tobacco filling power throughout the reconditioning process, i.e., there was no statistically significant loss of filling power as determined by the conventional variance analysis procedure. In addition, there was no measurable reduction in the size of the tobacco particles, as determined by the dampening test, during the reconditioning process. 31 V u

Experience # 6

A series of experiments were carried out using various types of expanded tobacco at different temperatures of the expansion tower where the tobacco was refurbished in accordance with the process of the present invention. In each experiment the reconditioning of tobacco at a rate of about 150 lb / hr (18.9 g / s) was performed, based on the mass of the refurbished tobacco, in the Frigoscandia-type modified autoelevator spiral unit described in Experiment No. The air conditions at the inlet of the reconditioning unit were set at a temperature of about 29øC (85øF) and relative humidity of about 62%. The air exiting the reconditioning unit was typically at a temperature in the range of about 32øC (90øF) to about 35øC (95øF) with a relative humidity of about 40% to about 45ø %. As shown in Table 5, reconditioned tobacco according to the process of the present invention did not reveal any significant loss of filling power.

Table 5

Balanced

Type of Experience Tower VE VE VC admission VE VC VE tobacco n ° (° C) admission exit (art.vg) admission exit out (%) (%) (%) (%) (%) Clear PO 205 C 288 2,70 11 , 16 9.93 11.87 9.40 12.00 ΕΌ 205A 321 2.11 11.58 10.41 11.57 10.83 11.56 PO 205B 329 1.87 9.99 11.30 11.30 10.90 11.50 Clear PO 206A 304 2.47 11.09 10.00 12.34 10.20 11.74 PO 217 321 2.59 10.86 10.49 11.79 10.51 11.63 Burley PO 206B 249 3.11 10.75 12.39 10.91 12.31 10.52 PO 206C 271 2.95 10.22 12.08 10.85 12.41 10.40 PO 214 271 3.00 10, 4 11.3 10.4 11.2 10.4

Experience # 7

Light tobacco, at a rate of approximately 25.3 g / s (200 lb / hr), with an LV content of about 21.6%, was introduced into the modified Frigoscandia autoclave unit described in experiment 5, to work as a drying unit. The tobacco circuit through the spiral drying unit has developed from the bottom to the top. The trajectory of the air flow has developed from the top to the bottom of the unit, thus obtaining a flow almost in countercurrent between tobacco and air. The tobacco dried well until a LV content of about 12.2% was obtained for a residence time of about 60 minutes using air whose inlet temperature was about 35øC (95øF) and whose HR on entry was about 35%. The air at the exit of the drying unit was at a temperature of about 28Â ° C (83Â ° F) and had an HR of about 62%. The tobacco at the entrance to and exit from the drying unit imparted a feeling of cold to the touch, with an estimated temperature of about 24 ° C (75 ° F), indicating that virtually no heat treatment of the tobacco took place. There was no change in the VC value of the balanced tobacco as a result of the drying process. This particular drying experiment is designed to minimize heat treatment. Similar drying results could be obtained by working at higher temperatures to achieve a controlled degree of heat treatment.

Notwithstanding the fact that the present invention has been particularly illustrated and described with reference to its preferred embodiments, it will be appreciated to those skilled in the art that various modifications of shape and details are possible without departing from the scope of the invention.

Lisbon, 12 April 2000

THE OFFICIAL PROPERTY OFFICER ΙΝΓΊ fSTRIAL

33

Claims (23)

V Process for increasing the moisture content of an organic material, which comprises the following steps: (a) preparing a bed of organic material by depositing said organic material on a spiral conveyor belt having a set of rows, (b ) contacting the organic material arranged in the bed with a stream of air having a relative humidity almost close to the equilibrium conditions of the organic material, passing the stream of air from spin to spinning in a trajectory practically countercurrent with the trajectory of the (c) increasing the relative humidity of the air stream contacting with the organic material laid down in the bed to increase the moisture content of said organic material, such that the relative humidity of the bed air contact with the organic material is maintained almost until this organic material has the desired moisture content, whereby the air stream is progressively dehydrated and the organic material is progressively hydrated as the air stream flows substantially countercurrently with the bed trajectory of organic material. A process for reducing the moisture content of an organic material comprising the steps of: (a) preparing a bed of organic material by depositing that organic material on a spiral conveyor belt having a set of rows, (b) contacting the organic material with a stream of air passing from spin to spin along a path substantially countercurrent with the path of the bed of organic material along a set of spinning streams, the air stream having a nearly equal relative humidity or lower than the equilibrium conditions of the bed of organic material and 1 Γ (c) decreasing the relative humidity of the air stream contacting the organic material as the moisture content of the organic material decreases, such that the relative humidity of the air stream contacting the material organic matter remains almost equal to or less than the equilibrium conditions of the organic material until the desired moisture content is reached in the organic material whereby the organic material is progressively dehydrated and the air stream is progressively hydrated as the air runs along a substantially counter-current path with the trajectory of the bed of organic material. A process according to any one of claims 1 or 2, wherein the temperature of the organic material is below about 38øC (100øF) before contacting the air stream. A process according to any one of claims 1 or 2, wherein prior to the step where the contact between the air stream and the organic material is established, it has an initial moisture content of between about 1.5 % and about 13%. A process according to claim 4, wherein prior to the step in which the air stream is contacted with the organic material, it has an initial moisture content of from about 1.5% to about 6% . A process according to claim 1, wherein the air stream contacting the organic material has a relative humidity of from about 30% to about 64% at a temperature of about 21 ° C (70 ° C). ° F) to about 49 ° C (120 ° F). A process according to any one of claims 1 or 2, wherein the organic material is tobacco. 2 V u A process according to claim 7, wherein the tobacco in question is expanded tobacco. A process according to claim 7, wherein the tobacco in question is fragmented tobacco. A process according to claim 7, wherein the tobacco is selected from the group consisting of expanded or non-expanded tobacco, whole tobacco leaves, fragmented or shred tobacco, stems, reconstituted tobacco or any combination thereof. A process according to claim 2, which further comprises the step of preheating the organic material to a temperature of about 100 ° F to about 250 ° F (121 ° C) before step (a). A process according to claim 2, wherein the temperature of the organic material is below about 121øC (250øF) prior to the step in which contact with the air stream occurs. A process according to claim 1, wherein the desired moisture content of the organic material following step (c) is from about 11% to about 13%. A process according to claim 2, wherein before the step of contacting the stream of air with the organic material, it has a moisture content of from about 11% to about 40%. A process according to claim 2, wherein the stream of air contacting the organic material has a relative humidity of from about 20% to about 60% at a temperature of about 21 ° C (70 ° C) ° F) to about 49 ° C (120 ° F). 3 V Γ u A process according to claim 2, wherein the temperature of the air stream is between about 24 ° C (75 ° F) and about 121 ° C (250 ° F). A process according to any one of claims 1 or 2, wherein the step in which the contact between the organic material and the stream of air takes place is carried out using a stream of air traveling at a speed between about 0.23 m / s (45 ft / minute) and about 240 ft / minute (1.22 m / s). A process according to any one of claims 1 or 2, wherein the step in which the contact between the organic material and the stream of air takes place is effected by sending a stream of air either downstream or upward through the bed of organic material or by simultaneously sending the streams of air downstream and upward through the bed of organic material. A process according to any one of claims 1 or 2, wherein the temperature of the air stream is chosen in order to carry out a desired heat treatment. A process according to any one of claims 1 or 2, wherein the temperature of the air stream is chosen so as not to perform any heat treatment. A process according to any one of claims 1 or 2, wherein the organic material in question is a hygroscopic organic material. A process according to claim 21, wherein the hygroscopic organic material is selected from the group consisting of fruits, vegetables, cereals, coffee, pharmaceuticals, tea and any combination thereof. 4 A method according to any one of claims 1 or 2, wherein the lift conveyor belt is a spiral conveyor belt and wherein the stream of air flows substantially through successive rows sequentially distributed in height. Lisbon, April 12, 2000 THE OFFICIAL AGENT OF INDUSTRIAL PROPERTY 5