BG62028B1 - Method for the regulation of the moisture content in tobacco - Google Patents

Abstract

Very small reductions of the CV value for tobacco in a stateof equilibrium, in practice without degradation, are produced bythe method for secondary wetting. The tobacco is in contact withan air stream of relative humidity close to the conditions of itsequilibrium state, and when the relative humidity of the airstream increases, the tobacco is moistened a second time. By themethod of drying, very small changes occur in the CV value fortobacco in a state of equilibrium, without significantdegradation. The tobacco is in contact with an air stream ofrelative humidity close or lower than the conditions of its stateof equilibrium, and when the relative humidity of the air streamis decreased, it is dried. The tobacco can be moistened a secondtime or be dried continuously using a self-loading spiralconveyor.

Description

(54) METHOD FOR ADJUSTING THE MOISTURE CONTENT OF TOBACCO

Technical field

The invention relates to a method for regulating the moisture content of tobacco. Specifically, the invention relates to the use of controlled humidity air to moisten or dry tobacco.

BACKGROUND OF THE INVENTION

There is a need to control the moisture content of various tobacco products. For example, tobacco that has been repeatedly processed to be used for making the final product has changed its moisture content several times. Each technological step, such as removing the stems, cutting, mixing the ingredients, adding flavoring additives, inflating and making cigarettes, requires some optimal moisture content, which must be carefully controlled to ensure high quality tobacco and of other hygroscopic organic matter.

Moreover, the way in which the moisture content of the tobacco changes can have a lasting effect on the physical, chemical and subjective characteristics of the finished product. Therefore, the methods used to change the moisture content of tobacco or other organic materials are of great importance.

Re-humidifying bloated tobacco is a process with many requirements. Typically, tobacco produced after inflating has a moisture content of less than 6%, and often below 3%. With such a low moisture content, the tobacco is very breakable. Furthermore, the structure of the swollen tobacco is easily destroyed by re-humidification, i. fully or partially returns to its undisturbed state. This causes losses in the mv filling properties and thus reduces the benefit of the swelling.

Different means have been used to re-moisten puffed tobacco. The most common method is to water the tobacco while it is being machined in a rotating cylinder. Another method is to use saturated steam as a re-humidifying medium. Another method is to purge high humidity air through a moving layer of tobacco on a conveyor, as shown in US 4 178 946.

None of the above methods is completely satisfactory for use in blown tobacco. Treating the tobacco with a water jet in a rotating cylinder causes the fragile swollen tobacco to break. Direct contact with water causes the structure of bloated tobacco to be destroyed. Re-moisturizing with steam also destroys the structure of the swollen tobacco. While this may be due in part to the high temperature of the medium created by the saturated steam, the exposure of the tobacco to this medium results in condensation of water, and the steam or the very humid air causes the structure of the tobacco to break down.

A method that is used to avoid these difficulties is to place dry, swollen tobacco in an air chamber having the desired moisture content, and to equilibrate the tobacco within the chamber for 24 hours to 48 hours. The air velocity through the chamber is kept very low, usually not greater than 0.127 m / s. With this method, there are no or very small defects in the structure of the swollen tobacco. The disadvantage of the method is the duration of 24 to 48 hours, which limits its use only for laboratory purposes.

Attempts have been made to reduce the time required to stay by increasing the speed of air. These attempts were unsuccessful because of the inability to maintain the filler qualities observed in the slow laboratory equilibration of the tobacco filling, the size of the conveyor required to carry the tobacco in order to adapt to the process duration, the heterogeneous content of the tobacco moisture and the possibility of fires in such devices as described in US 4 202 357.

The use of drying to control the moisture content of tobacco processing is equally important with its re-humidification. When the tobacco is dried, physical and chemical changes can occur that affect the physical and subjective qualities of the product. Therefore, the method of drying tobacco is extremely important.

There are two types of drying devices commonly used in the tobacco industry: drum dryers and belt dryers. In some cases, pneumatic type dryers are used. The type of dryer depends on the particular drying case. Tape dryers are generally used for example in tobacco tapes, while drum tumble dryers are used for sliced tobacco. Both drum and belt dryers are used for stem drying.

In belt dryers, the tobacco is spread on a perforated strip and the air is directed either up or down through the strip and through the tobacco layer. However, irregularly dried tobacco is obtained due to the channels that are formed by blowing through the layer and which allow the drying air to bypass the tobacco.

Most of the tumble dryers used in the tobacco industry are equipped with a steam coil and can function either as direct or indirect heat dryers, depending on whether heat is applied from outside or inside the oven casing. Therefore, they can act either on the principle of the direct motion of tobacco and air, or on the principle of counterflow when the flows of air and tobacco are opposite. Drum dryers must be carefully controlled to avoid overdrying, which causes both chemical changes and unnecessary breakage in rotary motion. In addition, when the outer surface of the tobacco is dried very quickly, an impermeable layer may be formed which makes it difficult to transfer moisture from the inside of the tobacco to its surface. The formation of such a layer slows down the drying rate and therefore results in uneven drying.

The use of a drum or belt dryer for tobacco drying can cause thermal changes that cause chemical and physical changes in the tobacco. Although these changes are not always undesirable, they are required to remove tobacco water. In typical tobacco applications, the need for drying for a limited time determines the result of the thermal effect of the drying step, which prevents the heat treatment from being optimized separately from the constraints imposed by drying.

US 3 879 857 describes a helical conveyor in which the tobacco material moves from the bottom to the top of the conveyor and introduces air into the conveyor. The air is fed down through the core of the coil conveyor and into each of its coils. The air passes through the periphery of each coil, then down the side of the coil and out into the exhaust air outlet. Thus, the air that has passed over the material of one coil does not come in contact with another coil and is expelled.

This arrangement has the disadvantage that the same airflow with the same humidity is applied to each coil material, regardless of the state of the material in that coil. As a result, it is not possible to maintain an ideal relative humidity regime in the air stream.

SUMMARY OF THE INVENTION

The invention relates to a method of regulating the moisture content of tobacco to a predetermined final level, which includes the following steps:

(a) formation of a layer of tobacco by pouring it on a spiral conveyor;

(b) transferring the tobacco poured onto the helical conveyor through the conveyor turns from the inlet through a first conveyor portion disposed intermediate from the inlet to the outlet of the helical conveyor, characterized in;

c) that at the same time as the transfer stage, an air stream having initially balanced relative humidity is created at the outlet of the helical conveyor, in the presence of which the moisture of the tobacco is balanced to a predetermined level of final moisture content, such as the relative humidity of the air inlet in the first conveyor part, and the relative humidity of the outlet air flow is determined in accordance with the respective tobacco content of the first and outlet tobacco, respectively. ontaktuva with the airflow as the airflow passes from coil to coil in the spiral conveyor countercurrently to the tobacco; and

(d) that the flow of air flowing counter to the tobacco is routed sequentially through the coils of the helical conveyor so that the tobacco and the air flow are maintained close to or under equilibrium between the first and the outlet portions of the conveyor, wherein either the air flow or the tobacco is progressively dehydrated and the other of the two is progressively hydrated as the airflow flows in the opposite direction of movement of the tobacco to reach the desired moisture content of the tobacco.

The advantage of the method is that the tobacco can be re-moistened or dried with little or no crushing, even brittle tobacco after it is inflated. The re-wetting of the blown tobacco is done without losing its structure or with little loss and ensures the drying of the tobacco at a pressure approximate to atmospheric, for example without the use of vacuum and at a suitably selected temperature, the heat treatment being controlled during the process to a degree not attained by the usual methods of drying tobacco.

In a preferred embodiment of the invention changes in the moisture content of the tobacco are made by contacting the tobacco with air having a relative humidity, carefully controlled above or below the equilibrium relative humidity of the tobacco with which it is in contact. The relative humidity of the tobacco is continuously increased or decreased accordingly while maintaining a controlled difference between the relative humidity of the air and the equilibrium relative humidity of the tobacco in contact with it. Careful continuous monitoring of relative humidity allows controlling the rate of moisture transfer between the tobacco and its environment, thereby minimizing structural changes in tobacco. The use of relative humidity as the main driving force for moisture transfer enables independent control of thermal impact. This process may be continuous or intermittent. In addition, the method can be carried out without the use of rotating cylinders and related tobacco crushing.

Description of the attached figures

Figure 1 is a diagram of the relative humidity (RH) of the air as a percentage of the moisture content of tobacco or OV;

Figure 2 is a schematic drawing of a laboratory device for re-humidifying the tobacco according to the invention by linearly changing the air relative humidity over time;

Figure 3 is a partial sectional view of an exemplary device for carrying out the method according to the invention in a continuous manner;

3a is a cross-sectional view of a portion of the helical conveyor of FIG. 3, which shows the air flow path with respect to the tobacco path;

Figure 4 is a schematic drawing of an alternative device suitable for carrying out the method of the invention on a periodic basis;

Figure 5 is a block diagram illustrating the application of the invention to the re-humidification method;

Figure 6 shows a graphical relationship between the relative humidity (RH) of the air in the vicinity of the tobacco relative to the time obtained during the re-humidification of the apparatus of FIG. 3.

The invention relates to a method for regulating the moisture content of tobacco, while minimizing crushing, changes in physical structure or thermally induced changes in the chemical composition of the tobacco to be processed. In particular, the invention relates to the use of controlled humidity air for re-humidifying or drying tobacco or other suitable hygroscopic organic material. The moisture content of the tobacco or other suitable hygroscopic organic material is increased or decreased by gradually and continuously increasing or decreasing respectively the relative humidity of the air in contact with the tobacco or with other suitable hygroscopic organic material. In this way, moisture transfer is controlled, which allows the other variables of the method, such as temperature, air velocity and air pressure, to be optimized individually.

Two commonly used methods for characterizing the physical structure of tobacco are the determination of the cylindrical volume (CV) and the specific volume (SV). These measurements are particularly valuable for achieving good results from tobacco re-moisturization.

Cylindrical volume / CV /

Tobacco stuffing material weighing 20 g if not swollen or 10 g if swollen is placed in a cylindrical densimeter (diameter measuring device) 6 cm in diameter, model No. DD-60, designed by Heinr. Borgwaldt Company, Heinr.Borgwaldt GmbH, Schnackenburgallee 15, Postfach 54 07 Feb 2000

Hamburg 54 West Germany. The tobacco mass was pressed with a piston with a weight of 2 Kg and a diameter of 5.6 cm for 30 s. The resulting volume of compressed tobacco is counted and divided by the weight of the tobacco sample to give a cylindrical volume (cylinder volume) in cm ³ / g. This experience determines the apparent volume of a tobacco filling weight. The resulting volume is taken to be a cylindrical volume. This test was performed under standard ambient conditions, namely 23.89 ° C and 60% RH (RH).

Usually, despite some opposing views, the tobacco sample is pretreated in this medium for 24-48 hours.

Specific volume / SV /

The term "specific volume" is a unit for measuring the volume occupied by solids, i. E. tobacco using the Archimedes Law of Displaced Liquid. The specific volume of a body is determined by taking the inverse of its density. It is measured in cm ³ / g. Suitable methods for these measurements are mercury porosity and helium pycnometry, which show good results.

When helium pycnometry is used, the weighed sample of tobacco, or as / ie. in its original state /, dried at 100 ° C for 3 h, or brought to equilibrium, was placed in a single cell of a quantum chromatopicnometer model 20421 (manufactured by Quantachrome Corporation, 5 Aerial Way, Syosset, New York). The cell is cleaned and loaded with pressurized helium. The volume of helium displaced by tobacco is compared with the volume of helium required to fill an empty test cell. Tobacco volume is determined on the basis of the fundamental principles of the Ideal Gas Law. In this annex, despite some controversial views, the specific volume of tobacco is determined using the same tobacco sample used to determine OV, i.e. tobacco, dried for 3 hours in a circulating air oven at a controlled temperature of 100 ° C.

As used throughout the text, moisture content can be assumed to be equivalent to that of volatile substances (OV), whereas no more than about 0.9% of the weight of tobacco is volatile substances other than water. Volatile matter determination is a simple measurement of the weight loss of a tobacco after staying in a circulating air oven for 3 hours at a controlled temperature of 100 ° C. Weight loss as a percentage of initial weight is the content of volatile substances.

Screening refers to a method of measuring the distribution of individual pieces by length for a sample of sliced tobacco filling. This test is often used as an indicator to reduce the length of pieces during processing. Tobacco stuffing weighing 150 ± 20 g if not swollen or 100 ± 10 g if swollen shall be placed in a vibrator. The vibrator contains a series of circular trellis tubs with a diameter of 30.48 cm / manufactured by W.S.Tyler, Inc., a subsidiary of Combustion Engineering Inc..Screening Division, Mentor, Ohio 44060 / according to ASTM standards. The usual dimensions of sieves for tubs are 6 mesh, 12 mesh, 20 mesh and 35 mesh. The vibrator running stroke is about 2.54 cm to 1.27 cm and its speed is 350 ± 5 rpm. The tobacco was stirred in the vibrator for 5 min, whereupon the tobacco sample was divided into batches of different particle sizes. Each of these batches is weighed to give a distribution of the tobacco sample according to the particle size.

Laboratory tests have shown that re-humidification of tobacco by exposure to high humidity air causes CV losses. It is clear that losses in the CV occur either during condensation processes or when moistened inside a layer of puffed tobacco.

Condensation processes occur when moist air comes in contact with tobacco, whose temperature is below the humidity condensation temperature. Moistening can occur when moisture changes inside the tobacco layer occur due to uneven exposure to moist air. Therefore, a successful humidification system with moist air must operate at a relatively low speed with good control of the relative humidity, air temperature, air flow and pressure across the tobacco bed.

This is best achieved by gradually increasing the moisture content of the moist air flowing through the tobacco in such a way that the tobacco is exposed to an air stream that is close to equilibrium with the tobacco.

In FIG. 1 line ABC is an isotherm for 23, 89 ° C for typical blown light tobacco. This isotherm gives the relationship between the OV of the tobacco and the RH of the surrounding air at a steady state for a given temperature. Point B indicates that at 23.89 ° C and at 60% RH, the swollen tobacco sample will have an OV of about 11.7% at steady state. The DEF line of FIG. 1 is a typical tobacco profile of RH that is re-humidified according to the invention. The GEF line is an alternative RH profile that can also be considered satisfactory. The HF line is a trajectory characteristic of the prior art such as laboratory re-humidification in an equilibrium chamber at very low air speeds. The IJ line represents the application of this invention for tobacco drying.

Figure 1 shows that re-humidification of tobacco from OV of about 6.5%, where it could be in equilibrium with air with RH about 30%, to OV value of about 11.7%, where it could to be in equilibrium with air with an RH of about 60% would have to be met by exposing tobacco to air whose humidity rises from about 40% RH in small increments over a period of time until RH reaches a value of about 60% , which is preferable to direct exposure to air with RH = 60%.

When under these slowly changing conditions, the mass transfer between the air flow and the tobacco is relatively slow because the driving force is small while maintaining the structure of the blown tobacco. Re-humidifying bloated tobacco without loss in CV can also be achieved by exposing tobacco to air whose moisture content increases from about 40% RH in small increments over a period of about 40 to 60 minutes until it reaches a value at RH = 62%. This reduces the total time required to complete the re-humidification process without significant changes in the structure of the swollen tobacco. Therefore, the two lines DEF and GEF of FIG. 1 are effective embodiments of the invention when tobacco is re-wetted.

FIG. 1 shows that the equilibrium states between air flow and tobacco are explained by the linear segment EF and the ABC line. It will be appreciated that at an OV value below 7%, the difference between the relative humidity of the equilibrium air with tobacco and the relative humidity of the humidified air stream used for re-humidification may be very large without adversely affecting the stability of the tobacco filling. It will also be appreciated that at OV values of about 7.5% to about 11.5%, the relative humidity of the humid air stream used for re-humidification may be from about 2% to about 8% above relative humidity of equilibrium air with tobacco, with the largest deviation from the equilibrium state corresponding to lower OV values without adversely affecting the stability of the tobacco filling.

When the method of the invention is used for tobacco drying, no tobacco CV losses are observed even when the relative humidity of the drying air stream is substantially below the relative humidity of the tobacco, i. E. .

the relative humidity of the drying air stream is under equilibrium conditions for tobacco. It is therefore clear that line IJ of FIG. 1 illustrates only one of the many possible trajectories that can be used in the drying of tobacco according to the invention.

The invention may proceed as a batch process or as a continuous process. When conducted as a serial re-humidification process, the relative humidity of the air in contact with the tobacco increases for some time to provide a continuous increase in the moisture content of the tobacco. This can be done in an artificial climate chamber, such as the one shown in FIG. 2. Re-moisten the tobacco in layers, forming a layer about 5 cm thick, in tubs with a sieve on the bottom, inside an artificial climate chamber so that the flow of controlled humidity air can flow through the tobacco in the downward direction. The dimensions of the chambers are from 0.566 t ³ to about 2.265 t ³ / manufactured by Parameter Generation and Control, Inc., 1104, Old US 70, West, Black Mountain, NC 28711 /. They have been used in a large number of studies. Artificial climate chambers are equipped with microprocessors that allow the linear change in the linear law of the humid air in the chamber to be controlled quickly. Attempts have been made in which dry blown tobacco has been re-moistened from starting OV values of 2% to end OV values of 11.5% by infinitesimal increments of RH from starting values from 30% to 52% to final values of 59 _% To 65% for 30-90 min. Air velocities from about 0.254 m / s to about 1.016 m / s were used. RH and temperature measurements are controlled with a Thunder 4A-I model tool (manufactured by Thunder Scientific Corp., 623 Wyoming, SE, Albuguergue, New Mexico 87123). Air velocity was measured with an Alnor heat anemometer model 8525 / manufactured by Agpog Instrument Co., 7555 N.Linder Ave, Skokie, Illinois 60066 /. In experiments in which the relative humidity changes linearly, starting values of 52% RH to final values of 62% RH for 40 min are obtained, resulting in re-humidified tobacco with full CV retention compared to similar tobacco, re-humidified in an air-conditioned room, maintained with 60% RH at 23.89 ° C and passing through the tobacco at low speed for 24-48 h. The rapid change is thus successful at a humid air velocity of about 1,016 m / s and at temperatures from 23,89 ° C to 32,22 ° C. The swollen tobacco, re-humidified in this way, shows minimal CV losses compared to the swollen tobacco, re-humidified in an adequately maintained artificial climate.

The invention can be accomplished as a continuous process most successfully in a self-priming Frigoscandia helical conveyor, such as that of FIG. 3. This device is a specially modified CGP 42 spiral freezer model designed by Frigoscandia Food Process Systems AB in Helsingborg, Sweden. The dry tobacco, which will be re-humidified, enters the device 10 on the conveyor 13, passes through the spiral 10 from the bottom to the top of the device 14, as shown, and exits the output 11 after re-humidification. The humidified air is blown down through the tobacco from the humidified air port 15 to the bottom of the spiral device 14, where it exits through the outlet port 16, the air flow being opposite to the tobacco flow, i.e. most of the moist air flow is from the top of the conveyor down through the layers of tobacco as the tobacco moves upwards following the coil of the conveyor. A small amount of humid air follows the conveying path of the conveyor from below, in a direction opposite to the direction of travel of the conveyor. These types of air flows are shown in FIG. For. This device largely replicates the efficiency of RH gain obtained in the device of FIG. 2.

In FIG. 3a, which is a cross-section of a portion of the helical conveyor 14 of FIG. 3 shows the airflow paths 20 and 22 relative to the path of the tobacco layer 21. As can be seen from FIG. For, the air flow moves from the top of the conveyor to its lower part (20 and 22). The tobacco stream is at the bottom of the conveyor and is shown in FIG. For as a right-to-left movement, following the path of the spiral. The main part of the air stream 20, which is in the opposite direction of the tobacco path, is directed through the layers of the tobacco layer 21 and comes into contact with the tobacco layer directly below it, while a small chat of the air stream 22 passes over the tobacco layer 21 in. direction opposite to the direction of tobacco. This portion of the air stream 22 may later pass through the tobacco layer 21.

One condition for the successful implementation of the invention in the case of re-humidification is the provision of a means of steadily increasing the relative humidity of the air in contact with the tobacco while increasing the OV of the tobacco. Frigoscandia's self-priming helical conveyor, thanks to its construction, conducts most of the air flow down through the numerous layers in the conveyor carrying the tobacco. When the tobacco is fed to the bottom of the conveyor and the humidified air at the top of the conveyor, the total flow of air and tobacco is countercurrent. This provides a natural long-lasting RH gradient in the air in contact with the tobacco because the air progressively dehydrates as it moves down the rows of tobacco when re-humidified.

With appropriate and careful selection of conveyor belt speeds, air and tobacco flow rates, and temperature and RH control of the inlet air, conditions such as those used in series laboratory re-humidification experiments can be approximated for a continuous process. To moisten approximately 55.95 kg / h of 3% OV blown tobacco, with bandwidths providing a duration of about 40 min to about 80 min and air at a temperature of about 23.89 ° C to about 35 ° C with a relative entry humidity of approximately 61% to 64% at an airflow of approximately 28.32 m ³ / min to about 70.8 m ³ / min using a modified Frigoscandia GCP 42 spiral device ensures complete satisfactory re-humidification without significant CV losses or measurable tobacco damage.

Relative humidity recording devices such as model 29-03 RH / Temperature recorder / manufactured by Rustrak Instruments Co. by E.Greenwich, RI / were mounted in the Frigoscandia device during the re-humidification of the tobacco.

These devices show a steady increase in relative humidity with initial RH readings from about 35% to about 45% at the bottom of the spiral conveyor where the tobacco is driest, to about 62% at the top of the conveyor where the tobacco is most - moisturized.

Figure 6 represents a typical RH curve over time, with values obtained with a Rustrak device. It gives the RH values of the air adjacent to the tobacco layer in%. The tobacco with an initial OV value of about 3% enters the spiral re-humidification conveyor and comes in contact with air with an RH of about 43% (point A in Fig. 6). Figure 6 shows how as the tobacco passes through the re-humidification coil, the RH of the air in the immediate vicinity of the tobacco increases from approximately 43% to 62% at the outlet of the device (b. In Fig. 6). When leaving the spiral device, the tobacco has an OV value of about 11%. The RH value of the air entering the re-humidification coil is controlled to obtain re-humidified tobacco without significant CV loss.

Other means of providing an increase in RH of the air, such as in FIG. 4 can also be used to carry out the invention on a continuous basis. As shown in FIG. 4, the tobacco enters the device through the inlet 40 of the conveyor 43 and exits through the outlet 41. Air with steadily increasing relative humidity is blown up or down. Through a layer of tobacco 42 in a plurality of zones 44, to multiply the effect of linear increase in the device of FIG. 2. The linear-law increase effect can be achieved by moving air from a single source along the right-to-left serpentine trajectory of FIG. 4, providing air flow in the opposite direction to the movement of the tobacco.

In this way, the air leaving a zone will become the inlet air for the next zone on the left.

For the process according to the invention, whole cleaned tobacco leaves, cut tobacco, puffed or non-puffed tobacco or selected parts of tobacco such as stems or reconstituted tobacco may be processed. The method may be applied to any or all of the above types of tobacco, with or without flavoring.

In the special case of tobacco drying, unblown tobacco can be dried for a long time at ambient air temperature opposite to the tobacco flow through a modified Frigoscandia self-priming helical conveyor, starting from a moisture content of approximately 21 % OV to 15% OV at a distance of approximately 1 hour. In this case, the air enters the upper part of the device at about 29.44 ° C and about 58% RH and exits at about 25 ° C and about 68% RH.

Drying is performed with little or no heat treatment of the tobacco.

Accordingly, the method according to the invention can be used to dry tobacco at a temperature substantially higher than the ambient temperature, i. tobacco with a temperature of about 93.33 ° C to

121.11 ° C. When tobacco in this temperature range is dried, the RH and the drying air temperature are adjusted to provide suitable conditions for the process of the invention.

By analogy with the re-humidification of tobacco, it is clear that drying is most successfully carried out for a minimum amount of time by adjusting the final moisture content of the air below what is necessary to achieve the desired final moisture content of the tobacco, thereby This increases the humidity gradient for air-tobacco and, accordingly, the driving force behind the drying process. Unlike the re-humidification process, the final moisture content of the air stream can be maintained at a level much lower than that which would be in equilibrium with the tobacco at the desired OV value after drying.

Examples of carrying out the invention

Example 1. To demonstrate the advantage of re-moistening dry blown tobacco by slow dosing and adding water to it compared to re-wetting in a jet cylinder, a 20 g sample of tobacco stuffing was placed in an airtight oven. The sample of tobacco is impregnated with liquid carbon dioxide and swollen in an expansion column at 287.78 ° C. The OV value of the swollen tobacco filling was 3.4%. It is estimated that approximately 1.89 g of water will be needed to increase the sample OV to 11.5%. this amount of water is placed in a small bottle with a rubber stopper through which a glass tube with an inner diameter of 0.32 cm is passed. The jar is also closed tightly in the oven. After ten days all the water is absorbed by the tobacco. The tobacco is then analyzed and an "as is" OV value of about 11.5% is established. The term "as is" used throughout the text refers to tobacco before being brought to equilibrium in an air-conditioned chamber with air maintained at 60% RH and 23.89 ° C passing through it at low speed for 24 to 48 hours. This equilibrium process is typically used to bring the tobacco to a standard state before CV, SV and sieve measurements.

After this standard steady state, the tobacco, subjected to re-humidification in a drying cabinet, has a CV value of about 9.5 cm ³ / g and an SV of about 2.9 cm ³ / g at an OV value of about 11.6%.

For comparison, when a second sample of the same tobacco is placed directly inside the equilibrium chamber and re-humidified by equilibrium under standard conditions, after equilibration 0V is about 11.3%, CV is about 9.4 cm ³ / g and SV is about 2.7 cm ³ / g. A third sample of the swollen tobacco filler was re-wetted in a jet cylinder to one "as is" value of an OV of about 11.4%. After reaching steady state, this sample has a CV of about 8.5 cm ³ / g and an SV of about 1.9 cm ³ / g at an OV equilibrium value of about 11.6%.

As can be seen from the data in Table 1. the tobacco sample re-moistened in a drying chamber by slow addition of water showed a significant improvement in the equilibrium values of CV and SV compared to the results of the sample moistened again in a jet cylinder. This sample also shows a slight improvement in the CV and SV values compared to the corresponding sample values placed and processed directly in the equilibrium chamber.

Table 1

Sample Existing "as is" position In equilibrium OV (%) SV (cm ³ / g) OV (%) CV (cm ³ / g) SV (cm ³ / g) Expansion Column 3.4 3.0 11.3 9,4 2.7 Jet Cylinder 11.5 1.8 11.6 8.5 1.9 Drying cabinet 11.5 2.7 11.6 9.5 2.9

A second series of experiments was conducted using an air-conditioning chamber to re-moisten the inflated tobacco filling. For this purpose a PGC camera (Parameter Generation and Control) was used. This camera is equipped with a Micro-Pro 2000 microprocessor, supplied by PGC Inc., which allows the linear growth of the conditions inside the camera to be controlled.

Example 2. A sample weighing approximately 1359 g of light tobacco impregnated with liquid dioxide and swollen under conditions similar to those described in Experiment 1 was placed with a layer thickness of about 5 cm inside the tub. The tub, which has solid walls and a sieve at the bottom, is placed inside an air conditioning chamber. The sample was re-humidified for 1 h using 35 air with a temperature of about 23.89 ° C and an initial RH value of about 36%, which increased to a final value of about 60%.

The air movement is down through the tobacco bed at a speed of about 0.228 m / s. This experiment was then repeated at 3 h, 6 h and 12 h intervals. The results presented in Table 2 show that for periods of increase of up to about 6 hours, the rewetting rate affects the values of CV and SV for tobacco under these experimental conditions. The lower the rewetting rate, the higher the CV and SV values are observed. Moreover, re-humidification according to the invention results in a CV greater than at least about 1 cm ³ / g and an SV greater than at least about 0.2 cm ³ / g of the values observed for tobacco treated in a jet cylinder. However, it should be noted that a significant part of this success is achieved through a linear increase within one hour.

Table 2

Sample Existing position Balanced in a climate chamber OV (%) SV (cm ³ / g) OV (%) CV (cm ³ / g) Expansion Column 3.10 3.06 11,33 9.71 Jet Cylinder 11.51 1.61 11,37 8.61

Table 2 (continued)

Increase 1 h 10.83 1.85 11,38 9.72 Increase 3 h 11,44 1.88 11,36 9.81 Magnification 6 h 11,45 1.90 11.30 9.88 Raise 12 h 11,41 1.97 11,27 9.89

EXAMPLE 3 A laboratory study was conducted on the effect of the rate of re-humidification and temperature on the values of CV and SV for tobacco. Seven series of experiments were performed using carbon dioxide-impregnated tobacco and expanded in an expansion column at 287.78 ° C. The swollen tobacco is re-moistened by the following methods:

1) By equilibration for 24 hours in an air-conditioning chamber at 60% RH 25 and 23.89 ° C by air movement through the tobacco at a speed of about 0.127 m / s;

2) By spraying with water to increase OV to about 7.5%, then equilibrating at 60% RH and 23.89 ° C for 24 h as indicated in subparagraph 1);

3) By spraying with water to increase the OV to about 7.5% and then finally re-wetting it in a jet cylinder; 35

4) By spraying with water to about 7.5% OV and then using moist air with an increase from initial RH of about 46% to a final RH of about 60%; and

5) By linear increase with 40 humid air from about 46% RH to about 60% RH.

Re-humidification with humid air is carried out inside a PGC air-conditioning chamber equipped with a microprocessor to control the magnification at selected intervals. The conditions under which the processing is carried out are as follows:

Increase intervals 30.60 and 90 min;

Air temperature 23.89 ° C and 35 ° C;

Air velocity: up through the tobacco layer - about 0.228 m / s and down through the tobacco layer - about 0.89 m / s;

Tobacco layer thickness 5 cm.

Tobacco used for all re-humidification methods, excluding of treatment in a jet cylinder, is collected at the outlet of the expansion column after inflating and sealed in double plastic bags before being re-moistened.

As a result, the tobacco is cooled by 93.33 ° C, ie. the temperature of the tobacco in the expansion column to ambient temperature before re-humidification. When re-humidification is performed by linearly increasing at about 35 ° C, the tobacco, while still in the plastic bags, is pre-heated to a temperature sufficient to avoid condensation in contact with moist air before being exposed to rapid conditions. raise. Data on these trials are provided in Table 3a-Ze.

Table 3

Sample Existing position Steady state OV /% / SV 1pc ² 1% / OV /% / CV / cm ³ / g / X Column Extension Output 3,43 3.02 11,31 9.04 S Through a nebulizer 8.06 2.14 11,68 8.66 With Through atomizer and cylinder 11.53 1.81 11.59 8.59 F Through a nebuliser and subjected to an increase of 90 min / 46% RH to 60% RH, 23,89 ° C / 11,27 1.87 11.51 9.01 H Through a nebulizer and subjected to an increase of 90 min / 46% RH to 60% RH, 23,89 ° C / 10.96 1.98 11,36 9,48 I Sample H kept for 15 min at 60% RH and 23,89 ° C 11.54 1.95 11.56 9.40 J Through a nebulizer and increased for 60 min / 46% RH to 62% RH, 35 ° C / 10,37 2.38 11,28 9.85 K Sample J, State 15 min at 62% RH and 35 ° C 11.17 2.26 11,22 9.88

Table 3b

Sample Existing position Steady state OV /% / SV / cm ³ / g / OV /% / CV / cm ³ / g / X Column Extension Output 3.01 2.58 11,34 9.23 S Through a nebulizer 7.51 2.13 11,39 8.87 With Through atomizer and cylinder 11,86 1.59 11,64 8.07 F Through a nebuliser and subjected to an increase of 60 min / 46% RH to 60% RH, 23,89 ° C / 10.55 1.64 11,45 8.86 G Sample F kept for 15 min at 60% RH and 23,89 ° C 11.56 1.64 11,42 8.61 H Through a nebulizer and increased for 30 min / 46% RH to 60% RH, 23,89 “C / 10,28 1.97 11,27 8.99

Table 3b (continued)

I Sample H kept for 15 min at 60% RH and 23,89 ° C 11,73 1.82 11,25 8.61

Table Zc

Sample Existing position Steady state OV /% / SV / cm ³ / g / OV /% / CV / cm ³ / g / A Output column extension 1.81 2.78 11,37 9.23 In Increase of 60 min / 46% RH to 60% RH, 35 ° C 10.91 1.86 11,47 8.86 C Increase 60 min / 46% RH to 60% RH, 23,89 ° C / 10.53 2.02 11,28 9,20 D Increase 90 min / 46% RH to 60% RH, 35 ° C / 10.84 1.99 11,45 8.90 E Through a nebulizer 5.39 2.37 11,25 8.71 F Through a nebulizer and directly at 60% RH, 35 ° C for 30 min 10.80 1.81 11,27 8.39 G Through a nebulizer and magnification 60 min / 46% RH to 60% RH, 35 ° C / 10.66 1.85 11,23 8.65 H Through a nebulizer and magnification 90 min / 46% RH to 60% RH, 35 ° C / 10.76 1.82 11,24 8.62 I Through a nebulizer and magnification 60 min / 46% RH to 60% RH, 23,89 ° C / 10,65 1.90 11,23 8.75 J Through a nebulizer and magnification 90 min / 46% RH to 60% RH, 23,89 ° C / 10.57 1.87 11,38 8.74 K Through a nebulizer and directly at 60% RH, 23,89 ° C for 30 min 10.73 1.87 11,22 8.64 L Through a nebulizer and cylinder 10.98 1.60 11,39 8.28

Table 3d

Sample Existing position Steady state OV /% / SV / cm ³ / g / OV /% / CV / cm ³ / g / T1 Output column extension 2.83 3.01 11,92 9.46 T2 Directly at 60% RH, 23.89 ° C for 30 min 11,24 2.27 11,77 9.08 TK Increase 90 min / 46% RH to 60% RH. 23.89 ° C / 11.08 2.24 11,83 9.29 T4 Increase 90 min / 30% RH to 60% RH, 23.89 ° C / 9.77 2.39 11.85 9.43 S1 Through a nebulizer 4.78 2.82 11,66 8.98 S2 Through a nebulizer and directly at 60% RH. 23.89 ° C for 30 min 11,10 2.19 11,64 8.89 S3 Through a nebulizer and an increase of 90 min / 46% RH to 60% RH, 23,89 ° C / 10.54 2.25 11,27 9.05 S4 Through a nebulizer and an increase of 60 min / 46% RH to 60% RH. 23.89 ° C / 10.56 2.22 11,73 9.03 S5 Through a nebuliser and increase 30 min / 46% RH to 60% RH, 23,89 ° C / 9.74 2.29 11.67 9.19 C Through a pulverizer and cylinder 10,48 1.95 11.81 8.80

The data presented in Tables 3a-Ze show that the results are approximately 0.5 cm ³ / g to 1 cm ³ / g in CV and approximately 0.3 cm ³ / g to 0.4 cm ³ / g in SV can be achieved by re-humidifying the cooled tobacco / i.e. tobacco at about 23.89 ° C to 35 ° C / s with linearly varying magnification parameters compared to re-humidification in a hot-tobacco jet cylinder 45 exiting the expansion column. Direct re-humidification of tobacco exiting the expansion column is preferable to two-stage processing, namely: tobacco spraying to increase OV to about 7% and then re-humidifying. No significant difference was observed in the CV or SV values of tobacco re-humidified by linear increase using moist air with an initial RH value of about 46% compared to tobacco re-humidified with air having a RH value about 30%, or in these values for tobacco, re-humidified for a period of 60 minutes or 90 minutes.

It is observed that the tobacco can be re-humidified or by moving the air down through the tobacco layer at speeds of about 175 ft / min or 0.898 m / s to 235 ft / min or 1.194 m / s. or by moving the air up through the tobacco bed at a speed of up to 45 ft / min or 0.228 m / s without significant differences in CV or SV values. In addition, it is observed that linear humidity re-humidification results in equivalent or better values of CV and SV compared to tobacco re-humidified by direct humidification at 60% RH and 23.89 ° C after exiting the expansion column. Finally, it was found that spraying with water to increase the OV values to about 7.5%, followed by an increase in linear law parameters with moist air, leads to better CV and SV values than spraying followed by final re-wetting in a jet cylinder.

Table Ze

Conditions of increase Existing position In equilibrium Home OV (%) Average speed Time (min) of air (fg / min) Temperature (° F) RH range (%) OV (%) SV (cm ³ / g) OV (%) CV (cm ³ / g) Power column 15.40 0.79 11,86 5.05 Exit column 3.94 2.82 11,72 9.49 Exit stage I - Sweaters- 5.64 2.72 11,82 9,48 sighting Exit cylinder 10,36 2.04 11,66 9.28 A 3.9 235 60 75 30-58 6.67 2.39 11,65 9.76 IN 5,6 175 60 75 30-58 8.44 2.45 11,82 9.91 P 3.9 190 60 75 45-58 7.83 2.25 11,65 9.57 D 5,6 190 60 75 45-58 8.44 2.39 11,79 9.66 Well 3.9 190 60 75 47-62 11,10 2,33 11,74 10.02 F 5,6 175 60 75 47-62 10,10 2.41 11.59 10.08 Mr 3.9 180 60 75 30-62 8.13 2.20 11,89 9.63 N. 5,6 175 60 75 30-62 9.41 2.41 11,79 10.11 1 3.9 200 60 75 47-62 10,21 2.15 11,76 8.98 J 3.9 180 60 75 47-64 10:18 2.13 11,94 9.03 K. 3.9 180 60 75 35-64 9.07 2.23 11,90 9.51 L 3.9 180 60 90 35-60 8.65 2.17 12.09 8.59 M. 3.9 180 60 90 45-60 10.11 2.39 11,92 10.02 N 5,6 180 60 90 45-60 10.08 2.39 11,93 10.02 0 3.9 240 60 90 47-64 10.88 2,31 11,96 9.51 R. 3.9 240 60 90 47-64 11.30 2,33 11,95 9.30

Example # 4

Tests have been conducted to determine the effect of air flow and air velocity on drift, channel formation, and tobacco compaction. Two PGC air conditioners are used.

The actual air movement in both chambers is approximately 14.16 m ³ / min. the air moves upward through the tobacco layer in one PGC chamber and down through the tobacco layer in the other chamber. Tobacco samples about 5 cm thick are placed in 5 x 3/4 tubs, which are open at the top and with a sieve at the bottom.

The tubs have solid walls with a height of 10.16 cm. These tubs are placed on shelves inside the air-conditioning chamber, air is pumped through the samples, the unoccupied area of the shelves is covered with cardboard and all gaps are sealed with tape. The air velocity changes as the number of sample containers the air passes through changes. The tobacco used for these experiments is carbon dioxide impregnated and inflated at 287.78 ° C. The re-humidified tobacco goes through the first stage, which is sprayed with water up to about 8% OV, immediately after inflating. The conditions inside the chambers are controlled and during the tests their values are about 23.89 ° C and about 60% RH. Two anemometers are used to measure air velocity, namely: blade anemometer (Airflow Instrumentation, model, LCA 6000, Frederick, Maryland) and thermal (Alnor Instrument Company, Skokie, Illinois, model 8525). These instruments shall be placed immediately above or below the sample to measure upward or downward air traffic, respectively.

With the upward movement of the air, there is a slight rise in the tobacco at the moment when the air passes at an average speed of about 26 ft / min or 0.13 m / s. Then small air ducts are formed and the tobacco settles. As a result, the air flow through the tobacco bed is very uneven / about 22 feet / min or 0.11 t / s to about 45 feet / min or 0.23 m / s for an average speed of about 0.13 m / s. With increasing speed, the formation of channels that are visible increases, and at values above 0.23 m / s, a significant blowout of the top layer of tobacco is observed, followed by significant channel formation in the layer of tobacco.

When the air is moving down, there is a certain compaction of the tobacco and a corresponding decrease in the air velocity through the layers of tobacco. This is shown in a table

4. At an initial velocity of about 192 ft / min or 0.975 m / s, the compaction of the tobacco bed is about 28% and as a result, the air velocity through the bed is reduced to about 141 ft / min or 0.716 m / s. At an initial air velocity of about 0.716 m / s or less, the compaction of the tobacco is about 50% of that observed at an initial velocity of 0.975 m / s and the air flow through the tobacco bed is at a much slower rate.

Table 4

Effect of layer compaction on the velocity of air passing through the layer

Airspeed / ft / min / Layer thickness / inches / Home Extreme Change% Home Extreme Change% 192 141 27 2 1.45 28 161 144 11 2 1.65 18

Table 4 (continued)

141 133 6 2 1,70 15 104 98 6 2 1.80 10 43 41 5 2 1.90 5

Note: 100 ft / min = 0.508 m / s inches = 2.54 cm

Based on the above attempts, it is determined that the swollen tobacco may be re-moistened, preferably by linear increase under the following conditions:

a) Time: from about 60 minutes to about 90 minutes;

b) RH: from an initial value of about 30% to 45% to a final RH value of about 60-64%;

c) Temperature: from about 23.89 ° C to 35 ° C

d) Airflow velocity: up to 0.23 m / s and down to 1.19 m / s.

Example 5. A mixture of light and Barley tobacco, in an amount of 55.95 kg / h, impregnated with carbon dioxide by the method described by Cho et al., In unresolved application SN 07/717 067, and inflated as follows described in the examples described above, passed through a cooling conveyor to reduce its temperature from about 93.33 ° C to 29.44 ° C before being fed into a self-primed modified Frigoscandia helical conveyor, model GCP 42. The tobacco stream , deposited on a helical conveyor, is conveyed by means of the turns of the conveyor from the inlet through one first part of the conveyor, and the intermediate of the inlet portion to the outlet portion of the spiral conveyor. At the same time as the transfer stage, an air stream having initially balanced relative humidity is created in the outlet of the helical conveyor, in the presence of which the moisture of the tobacco is balanced to a predetermined level of final moisture content. The airflow is from the top of the device down, i.e. back to the movement of tobacco. This device provides re-humidification of the tobacco with a linear increase as a result of the long-lasting dehydration of the air from the tobacco. Incoming tobacco is 3% OV and tobacco at the end of processing is 11% OV. The equilibrium value of the CV of the feed material is about 10.53 cm ³ / g, while the equilibrium CV value of the re-moistened material is about 10.46 cm ³ / g without significant loss of tobacco filling capacity during the process, t .f. without statistically significant loss of filling capacity, as determined by standard analysis of a variant process. In addition, there is no measurable reduction in the size of the tobacco particles during the re-wetting process, which is determined by sieve analysis.

Example 6

A series of trials are conducted using tobacco of different shapes and varieties, inflated at different temperatures. In these experiments, the tobacco is re-moistened according to the method of the invention. In each batch, approximately 55.95 kg / h of tobacco (based on the re-humidified tobacco mass) is subjected to re-humidification in a self-primed modified Frigoscandia helical conveyor described in Example 5. The air entering the device is at 29.44 ° C. and relative humidity (RH) of about 62%. The air exiting the device is typically at a temperature of about 32.22 ° C to 35 ° C and a relative humidity of 40% to 45%. As shown in Table 5, the re-moisturized tobacco according to the method of the invention shows no significant loss of filling capacity.

Table 5

Type TOBACCO Series # Column Temperature (° F) OV in (%> OV outside (%) CV in (cm ³ / g) In equilibrium OV in (%) CV outside (cm ³ / g) OV outside (%) Bright FO 205C 550 2.70 11.16 9.93 11,87 9.40 12,00 FO 205A 610 2.11 11.58 10,41 11,57 10.83 11.56 FO 205B 625 1.87 9.99 11.30 11.30 10.90 11.50 Bright FO 206A 580 2.47 11.09 10,00 12,34 10,20 11,74 FO 217 610 2.59 10.86 10,49 11,79 10.51 11,63 Barley FO 206B 480 3.11 10,75 12.39 10.91 12.31 10.52 FO 206C 520 2.95 10,22 12.08 10,85 12,41 10.40 FO 214 520 3.00 10.4 11.3 10.4 11,24 10.4

Example 7.

Approximately 74.6 kg / h of light tobacco with an OV of about 21.6% is fed for re-humidification to a self-priming modified Frigoscandia spiral device described in Example 5, acting as a drying device.

The flow of tobacco deposited on the spiral drying device is conveyed through the conveyor coils from the inlet through a first conveyor portion located intermediate from the inlet to the outlet of the helical conveyor and moves to ^ 0 the top of the conveyor . At the same time as the transfer step, an air stream is created in the outlet of the helical conveyor, which moves from the top of the device down to the bottom, i. back to the flow of tobacco. The tobacco was successfully dried to about 12.2% OV for about 60 minutes using air with an inlet temperature of about 35 ° C and an inlet relative humidity of about 35%. The outgoing air has a temperature of about 28.33 ° C and about 62% relative humidity. Tobacco entering and leaving the drying unit is cooled to 23.33 ° C. This temperature indicates that the tobacco is not heat treated. There is no change in the equilibrium value of tobacco CV as a result of drying. This drying experiment was conducted to minimize heat treatment. Similar drying results can be achieved by using higher temperatures to ensure a controlled degree of heat treatment.

From the described preferred embodiments of the invention, it will be apparent to those skilled in the art that different shapes and details can be made in the form and details without departing from the spirit and scope of the invention.

Claims (17)

Claims 1. A method of adjusting the moisture content of tobacco to a predetermined final level, comprising the steps of (a) forming a layer of tobacco by pouring it on a spiral conveyor; (b) transferring the tobacco poured onto the helical conveyor by means of the conveyor turns from the inlet through a first conveyor portion located intermediate from the inlet to the outlet of the helical conveyor, characterized in that (c) at the same time as the conveyance step in the outlet of the helical conveyor is an air stream having initially balanced relative humidity in the presence of which the moisture of the tobacco is balanced to a predetermined level of final moisture content, such as relative humidity of the air flow introduced into the first conveyor part and the relative humidity of the air flow at the outlet portion are determined in accordance with the respective moisture content of the tobacco in the first and in the outlet part, whereby the tobacco contacts the air flow as the air flow passes from the coil to a winding through the helical conveyor, mainly in the opposite direction to the tobacco; and (d) that the air flowing through the countercurrent with respect to the tobacco is routed sequentially through the coils of the helical conveyor so that the tobacco and the air flow are maintained close to or under equilibrium between the first and the outlet portions of the conveyor, in which either the air flow , or the tobacco is progressively dehydrated and the other of the two is progressively hydrated as the air flows in the opposite direction of movement of the tobacco, until the desired moisture content of the tobacco is reached. Method according to claim 1, characterized in that the equilibrium cylindrical volume of tobacco after step d) is equal to or greater than the equilibrium cylindrical volume of tobacco before step (b). Method according to claim 1, characterized in that the equilibrium cylindrical volume of the tobacco after step d) is equal to or greater than its equilibrium cylindrical volume before the step of passing the air flow from turn to turn through the coil conveyor. Method according to claim 1, 2 or 3, characterized in that the temperature of the tobacco is below 38 ° C before contact with the air stream. 5. A method according to claim 1, characterized in that, before the tobacco contact step with the air stream, it has an initial moisture content of 1.5 to 13%. A method according to claim 1, characterized in that before the tobacco contact step has an air flow, it has an initial moisture content of 1.5 to 6%. Method according to claim 1, characterized in that the desired moisture content of the tobacco after step d) is from 11% to 14%. A method according to claim 1, characterized in that the air flow in contact with the tobacco has a relative humidity of 30% to 64% at a temperature of 21 ° C to 49 ° C. A method according to claim 1, characterized in that the air flow temperature that provides the desired heat treatment of the tobacco is from about 24 ° C to about 121 ° C, while the relative humidity of the air stream providing regulation of the moisture content , is approximately 20 to 64%. A method according to claim 1, characterized in that it comprises a step of preheating the tobacco from 38 to 121 ° C before step (b). A method according to claim 1, characterized in that the temperature of the tobacco prior to the air flow contact step is 121 ° C. A method according to claim 1, characterized in that the tobacco has a moisture content of from 11 to 40% prior to the contact of the tobacco with the air stream. A method according to claim 1, characterized in that the air flow in contact with the tobacco has a relative humidity of 20 to 60% at a temperature of 21 ° C to 49 ° C. A method according to claim 1, characterized in that the air flow temperature is from 24 ° C to 121 ° C. A method according to any one of the preceding claims, characterized in that the tobacco is swollen or unblown, whole leaf tobacco, sliced or crushed, tobacco handles, recovered tobacco and any combination thereof. A method according to claim 1, characterized in that the tobacco contact step with the air stream is carried out using an air stream at a speed of 0.23 to 1.22 m / s. A method according to claim 1, characterized in that the step of contacting the tobacco with the air flow is carried out by directing the air flow down or up through the tobacco layer, or by directing the air flow simultaneously down and up through the tobacco layer.