FI103373B - A method for controlling the moisture 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

103373

Method for adjusting the moisture content of organic materials Förfarande för justering av fukthalten hos organiciska material

The present invention relates to methods for re-humidifying or drying moisture in tobacco or other hygroscopic organic substances such as pharmaceuticals and agricultural products such as, but not limited to, fruits, vegetables, cereals, coffee and tea. More particularly, the present invention relates to the use of humidity controlled air for wetting or drying these materials.

There has long been a desire in the art to control the moisture content of various organic materials, including tobacco. For example, the moisture content of tobacco processed into a usable product has been changed many times. Each stage of production, including straw removal, cutting, blending of components, flavoring, swelling and cigarette making, requires certain optimum moisture contents, which must be carefully adjusted for high quality tobacco and other hygroscopes! to obtain products of organic material. In addition, the way in which the moisture content of the tobacco is changed may have a lasting effect on the physical, chemical and subjective properties of the final product. Thus, the methods used to modify the moisture content of tobacco or other organic materials are important.

Increasing the moisture content of expanded tobacco is a particularly demanding measure. Tobacco from the expansion process typically has a moisture content of less than 6% and often less than 3%. Tobacco is very brittle when it has such a low moisture content. In addition, the structure of expanded tobacco tends to collapse when the moisture content is increased, that is, it tends to return, in whole or in part, to the state in which it was before expansion. This collapse results in a decrease in the filling capacity, which diminishes the benefit gained by the expansion process.

Numerous ways have been used in the art to increase the moisture content of expanded tobacco. The most common method is to apply a jet of water to the tobacco while the tobacco is typically spun in a rotating cylinder. Another method is to use saturated steam as a medium for increasing the moisture content. Still another method is to blow very moist air through the moving tobacco layer on the conveyor as described in US 4,178,946. The wetting of the organic material is also described in DE 1729411 and US 3,879,857.

None of the above methods has been found to be completely satisfactory in terms of its application to expanded tobacco. Rotating the tobacco in the injection cylinder will result in the breaking of the brittle expanded tobacco. Direct contact with liquid water tends to cause the structure of expanded tobacco to collapse. Increasing the moisture content with the help of steam also causes the structure of expanded tobacco to collapse. Although this may be attributed in part to the high temperatures in the vapor environment, exposing the expanded tobacco to any of the following: a gaseous environment with condensation of water, such as a vapor or high humidity environment, will result in collapse.

In one method used to overcome these difficulties, dry, expanded tobacco is placed in a chamber containing air of the desired humidity and the tobacco is allowed to equilibrate in the chamber for a period of 24 to 48 hours. Air velocity through the chamber is kept very low, at a maximum of 25 feet per minute (about 7.6 m / min). This operation causes little or no collapse of the expanded tobacco structure. However, the long periods of time required for this procedure, 24 to 48 hours, have limited its usefulness for laboratory applications.

3, 103373

Attempts have been made in the art to reduce the delay time necessary for such balancing methods by increasing the air velocity. Such attempts have been unsuccessful due to the inability to maintain the filling capacity found in the slow balancing of the laboratoryomita, the size of the conveyors required to carry the tobacco, which corresponds to the long delay required, the uneven moisture content of the tobacco product

Adjusting the moisture content by drying during tobacco processing is as important as increasing the moisture content. When drying, the tobacco may undergo both physical and chemical changes which affect the physical and subjective quality of the product. For this reason, the method for drying tobacco is very important.

There are two types of drying equipment commonly used in the tobacco industry: tumble dryers and belt or tape dryers. Occasionally pneumatic drying devices of the type are also used. The dryer used in each situation is selected with the required drying procedure in mind. For example, belt or tape dryers are normally used in the case of cut tobacco, while tumble dryers are used in the case of cut tobacco. Both tumble dryers and belt dryers are used to dry the strains.

In a belt dryer, tobacco is applied to the perforated belt and air is conducted either upwardly or downwardly through the belt and the tobacco layer. The tobacco then often dries unevenly due to the channels in the tobacco bed, whereby the drying air can pass through the tobacco in places.

Most tumble dryers used in the tobacco industry are lined with steam coils and can act as indirect or direct heat dryers depending on whether the heat is applied to the inside or outside of the tumble dryer. In addition, they can operate either downstream, with the tobacco and air flowing in the same direction, or upstream, with the tobacco and air flowing in opposite directions. Rotary drying must be carefully controlled to avoid over drying, which causes both chemical changes and unnecessary breakage of the tobacco as a result of the rotating motion. In addition, if drying takes place too quickly, an impermeable layer may be formed on the outer surface of the tobacco, which makes diffusion of moisture inside the tobacco difficult. The formation of such a layer slows down the drying rate and leads to uneven drying.

Using a tumble dryer or belt dryer to dry the tobacco can result in heat treatment that can cause chemical and physical changes in the tobacco. These changes, which are not always undesirable, result from the goal of removing water from tobacco. In typical tobacco applications, the need to dry tobacco over a limited period dictates the heat treatment result from the drying step and thus prevents optimization of the heat treatment in addition to the process limitations due to drying.

The present invention is defined in the appended independent patents! claims which are hereby referred to.

Embodiments of the present invention have the advantage that, without limitation, the moisture content of tobacco and other suitable hygroscopic products and agricultural products, including fruits, vegetables, cereal products, coffee and tea, can be increased or dried by breaking the product. little or no, even for brittle tobacco from the expansion process. Another advantage of the invention is that the moisture content of the expanded tobacco can be increased with little or no change in the structure of the expanded tobacco, and that the invention allows the tobacco or other suitable hygroscopic material to be dried at approximately atmospheric pressure, e.g. such that the heat treatment to be carried out can be adjusted during the process in a way that is impossible in conventional tobacco drying processes.

In a preferred embodiment of the process of the invention, the moisture content of the tobacco or other suitable organic materials is altered by contacting the tobacco with air whose relative humidity is carefully adjusted to be greater or less than the relative equilibrium humidity of the organic material with which the air is contacted. The relative humidity of the air is continuously increased or decreased during processing to maintain a controlled difference between the relative humidity of the air and the relative equilibrium humidity of the organic material with which the air is in contact. Careful continuous adjustment of the relative humidity enables the rate of moisture transfer between the organic material and its surroundings to be controlled so that the structural changes in the tobacco are kept to a minimum. The use of relative humidity as the main cause of moisture transfer enables autonomous control of the heat treatment. This process can be implemented either batchwise or continuously. Furthermore, the method can be carried out without the use of rotating cylinders and avoiding the fracture associated with their use.

Examples of processes illustrating the invention as well as preferred embodiments thereof will be described with reference to the accompanying drawings, in which:

Figure 1 is a graph showing the relationship between relative humidity (RH;%) and tobacco moisture (OV);

Figure 2 schematically shows laboratory equipment for increasing the moisture content of hygroscopic organic material according to the present invention by increasing the relative humidity of the air over time;

Fig. 3 illustrates an example of a piece of equipment from which a portion has been cut off and which can be used to carry out the present invention as a continuous process;

Figure 3A is a cross-sectional view of a portion of the stacked helical conveyor of Figure 3, showing this airflow path relative to the path of the hygroscopic organic material;

Figure 4 is a schematic representation of an alternative apparatus for implementing the present invention as a continuous process;

Fig. 5 is a block diagram illustrating the use of the present invention in a method for increasing the moisture content; and

Figure 6 shows a typical RH profile of the air adjacent to the tobacco over time obtained by increasing the moisture content in the apparatus of Figure 3.

The present invention relates to methods for adjusting the moisture content of tobacco and other suitable hygroscopic organic materials such as pharmaceuticals and agricultural products, including but not limited to, fruits, vegetables, cereal products, coffee and tea, such as fracture, alteration of physical structure or chemical changes in heat are minimized. More particularly, the present invention relates to the use of air having a controlled humidity for wetting or drying either tobacco or other suitable hygroscopic organic material. The relative humidity of the tobacco or other suitable hygroscopic organic material is either increased or decreased, respectively, by gradually increasing or decreasing the relative humidity of the air in contact with the tobacco or other suitable hygroscopic organic material. In this way, the humidity 7 103373 displacement can be controlled and other process variables such as temperature, air velocity and air pressure can be optimized separately.

Two commonly used methods for characterizing the physical structure of tobacco are cylinder volume (CV) and specific volume (SV). These measurements are particularly valuable in evaluating the benefits of this process for increasing the moisture content of tobacco.

Cylinder capacity (CV)

A 20 g tobacco filler, if unsweetened, or 10 g if expanded, is placed in a 6 cm diameter Densimeter cylinder, model DD-60, designed by Heinr. Borgwaldt Company, Heinr. Borgwaldt GmbH, Schnackenburgallee 15, Postfach 54 07 02, 2000 Hamburg 54, Federal Republic of Germany. On top of the tobacco in the cylinder is placed a 2 kg piston of 5.6 cm diameter for 30 seconds. The resulting volume of compressed tobacco is determined and divided by the weight of the tobacco sample to give a cylinder volume in cm3 / g. This test can be used to determine the apparent volume of a given amount of tobacco fill. The resulting fill volume is expressed as cylinder volume. This test is conducted under standard ambient conditions with a temperature of 75 'F (about 23.9 * C) and a relative humidity of 60%; usually, unless otherwise noted, the sample is pre-conditioned in this environment for 24-48 hours.

Specific volume (SV) The term "specific volume" is a measure of the volume of solid objects,. for example, tobacco, space requirements, and it is based on liquid displacement according to Arkimedes law. The specific volume of a body is defined as the inverse of its true density. The specific volume is expressed in cm3 / g. These measurements can be made both as mercury porosity and helium pycnometry, and the results have been found to be well correlated. Using helium pycnometry, a weighed sample of tobacco, either "as such", dried at 100 ° C for 3 hours 8 103373 or equilibrated, is placed on a Quantachrome Penta-Pychnometer Model 2042-1 (manufactured by Quantachrome Corporation, 5 Aerial Way, Syosset, New York). ) to the cell. This cell is then rinsed and pressurized with helium. The volume of helium displaced by the tobacco is compared with the volume of helium needed to fill the empty sample cell. The volume determination of tobacco is based on the basic principles of the Ideal Gas Act. In the appended application, unless otherwise noted, the specific volume is determined using the same tobacco sample as in the OV test, i.e., dried tobacco held for 3 hours in a convection oven set at 100 ° C.

As has been done herein, the moisture content can be considered equal to the volatile matter content (OV), since no more than about 0.9% by weight of the tobacco contains volatile substances other than water. The determination of oven volatile matter is a simple measurement based on tobacco weight loss, where the tobacco is held for 3 hours in a convection oven set at 100 ° C. The content of volatile substances in the oven is weight loss as a percentage of the original weight.

"Screening test" means a method by which the length of a torn sample in a sample of a cut filler can be measured. This test is often used to demonstrate the degradation of the torn length during treatment. A tobacco filler weighing 150 ± 20 g, if unsweetened, or 100 ± 10 g, if expanded, is placed in a shaking apparatus. This shaker uses several circles. 12 inch (about 30.5 cm) screens (manufactured by WS Tyler, Inc., a subsidiary of Combustion Engineering, Inc., Screening Division, Mentor, Ohio 44060) and manufactured by ASTM (American Society of Testing Materials). Normal screen sizes for screening plates are 6 mesh, 12 mesh, 20 mesh and 35 mesh. In this device, the shaking distance (stroke) is about 1.5 inches (3.8 cm), and the shaking speed is 350 ± 5 rpm. The shaker shakes 9,103,373 tobacco for 5 minutes to separate the sample into different particle sizes. Each particle size batch is weighed to obtain a particle size distribution for the sample.

Laboratory tests have shown that attempts to rapidly increase the moisture content of tobacco by treating it with extremely humid air have resulted in CV losses. Similarly, it has been shown that CV losses occur when there is either condensation or overheating in the layer of expanded tobacco. Condensation occurs when moist air comes into contact with tobacco having a tobacco temperature below the dew point of moist air. Overheating may occur when the tobacco bed generates different levels of humidity as a result of the tobacco not being in uniform contact with humid air. Therefore, in order to increase the moisture content of a successful humidified air system, it is necessary to operate relatively slowly and carefully adjust the air relative humidity, air temperature, air flow and pressure through the tobacco bed. This is best achieved by gradually increasing the moisture content of the humid air passing through the tobacco so that the tobacco comes into contact with an airflow that is nearly in balance with the tobacco.

l0 103373 using very low air speeds. In Figure 1, line IJ represents the application of the present invention to the drying of tobacco.

Figure 1 shows that increasing the moisture content of the tobacco from about 6.5% of the OV value, whereby the tobacco would be equilibrated with air having an RH of about 30%, to about 11.7%, where the tobacco would be equilibrated with the air having RH of about 60% can be accomplished by treating the tobacco with air that raises relative humidity from about 40% to about 60% over a period of time, instead of directly treating the tobacco with 60% relative humidity. Under these slowly changing conditions, the transfer of material between the air stream and the tobacco occurs relatively slowly because of the low force required to maintain the structure of expanded tobacco. Increasing the moisture content of expanded tobacco without any change in CV can be accomplished by treating the tobacco with air that is gradually increased from about 40% relative humidity over a period of about 40 to about 60 minutes to about 62% relative humidity. This, however, shortens the total time needed to increase the moisture content without significantly altering the structure of expanded tobacco. Thus, in Figure 1, both the DEF and GEF lines represent effective embodiments of the present invention while changing the moisture content of the tobacco over time.

In Figure 1, the near-equilibrium conditions between the airflow and the tobacco are illustrated by the subdivision EF and vii; municipal ABC. Note that when the OV value of the tobacco is less than about 7%, the difference between the relative humidity of the air at equilibrium with the tobacco and the relative humidity of the moist air stream used to increase the moisture content can be quite large without adversely affecting the tobacco filling power. Likewise, it is clear that when the OV content of the tobacco is in the range of 7.5 to 11.5%, the relative humidity of the moist air stream used to increase the moisture content may be about 11 to 103373 greater than the relative humidity of the air equilibrated with the tobacco. The greater deviation from the equilibrium corresponds to the lower OV content of the tobacco, without adversely affecting the filling power of the tobacco.

When the present invention was applied to drying tobacco, no measurable loss in tobacco CV was observed. This was the case even when the relative humidity of the drying air stream was significantly lower than the relative humidity of the air in equilibrium with the tobacco, i.e., the relative humidity of the drying air stream was below the equilibrium conditions of the tobacco. Accordingly, it should be noted that in Figure 1, line IJ illustrates only one of several possible routes that can be used to dry tobacco in accordance with the present invention.

The present invention may be implemented as either a batch process or a continuous process. When implemented in batches, the relative humidity of the air stream in contact with the tobacco is increased over time in order to continuously increase the moisture content of the tobacco. This can be done in an environmental chamber such as that shown in Fig. 2. Tobacco, which is to be increased in moisture content, is applied in layers of about 2 inches (about 5 inches)! screening plates inside this environmental chamber so that the air stream, which is controlled for relative humidity, can pass through the tobacco downwards. Chambers ranging in size from about 20-80 ft3 (about 566-2265 liters) (manufactured by Parameter Generation and Control, Inc., 1104 Old US 70, West, Black Mountain, N.C. 28711) were used: in numerous studies. These environmental chambers were equipped with microprocessors to control humid air conditions in the chamber in a controlled manner. In this context, experiments were carried out in which the moisture content of dry expanded tobacco was increased from a baseline of about 2% to a final OV level of about 11.5%, gradually increasing the relative humidity starting from as low as 12,103,373 to about 30% and as high from about 52% of baseline over about 30-90 minutes to about 59-65% of final relative humidity. Air speeds in the range of about 50-200 ft / min (about 15-61 m / min.) Were used in the experiments. RH and temperature measurements were followed by a Thunder model 4A-1 instrument (manufactured by Thunder Scientific Corp., 623 Wyoming, S.E., Albuquerque, New Mexico 87123). Air velocities were measured with an Alnor Thermo Anemometer, Model 852 5 (manufactured by Alnor Instruments Co., 7555 N. Linder Ave. Skokie, Illinois 60066). Experiments that raised relative humidity from as high as 52% from baseline to as high as about 62% in the final RH in as short a time as 40 minutes resulted in wetted tobacco with perfectly maintained CV compared to similar moisture content modified in an environmentally controlled room where the relative humidity of the air was maintained at 60% and the temperature at 75 ° F (about 23.9 ° C), and where air was passed through the tobacco at low speed for 24-48 hours. The humidity was successfully increased at humid air speeds as high as about 200 ft / min (about 61 m / min) and temperatures in the range of about 75-90 ° F (about 23, 9-32, 2 'C). Expanded tobacco with a moisture content increase in this manner was found to have very little, if any, decrease in CV value compared to expanded tobacco with a moisture content increase at a controlled environment.

The present invention can be implemented as a continuous process most effectively in, for example, the Frigoscan slide self-stacking screw conveyor shown in Figure 3. This appliance is a specially modified GCP 42 threaded freezer, supplied by Frigoscandia Food Process Systems AB, Helsingborg, Sweden. The wettable dry tobacco is conveyed to the unit 10 by a conveyor 13, conveyed through the unit 10 following a helical geometry from the bottom of the screw stack 14 to its peak, as the tobacco exits the device 13 103373 after being wetted. The humidified air is blown downwardly through the tobacco from the wet air inlet 15 to the bottom of the twist stack 14 where it exits through the wet air outlet 16, flowing substantially upstream of the tobacco direction, i.e., following. A small portion of the moist air follows the convoluted path of the conveyor from top to bottom, completely upstream. These types of air flows are illustrated in Figure 3. It has been found that such an arrangement effectively mimics the manner in which the relative humidity is increased in the device of Figure 2.

Reference will now be made to Figure 3a, which is a cross-sectional view of a portion of the helical conveyor stack 14 of Figure 3, which also shows airflow paths 20 and 22 relative to the path of the tobacco layer 21. As shown in Figure 3a, the air flow 20 and 22 occurs downward from the top of the stack. The tobacco moves from the bottom of the unit to its peak, and in Fig. 3a it is shown moving from right to left as it proceeds along the helical conveyor stack 14. Most of the airflow 20, which occurs substantially upstream of the tobacco path, is directed through the overlapping tobacco layers 21 and contacts the tobacco layer immediately below, while a small portion of the airflow 22 passes over the tobacco layer 21 in the direction opposite to the tobacco path 21. This airflow portion 22 may subsequently pass through the tobacco layer 21.

When raising the moisture content, the most important consideration for the successful implementation of the invention is the ability to continuously increase the relative humidity of the air in contact with the tobacco as the OV content of the tobacco increases. In the self-stacking Fri-goscandia screw conveyor, due to its self-stacking structure, most of the airflow is channeled down through the many layers of the conveyors (tobacco stack) which carry the tobacco. When the tobacco is fed to the bottom of the stack of conveyors and the humidified air is led to the top of the stack, the total air and tobacco flows are substantially upstream. This substantially upstream flow provides a natural continuous RH gradient in the air in contact with the tobacco, since water is continuously evacuated from the air as it moves downward through the layers of tobacco to be wetted. By choosing the conveyor belt speed and air and tobacco flow rates sensibly, and by appropriately adjusting the incoming air temperature and RH, it is possible to mimic the conditions used in batch laboratory laboratory measurements to gradually increase the moisture content. For example, increasing the moisture content of expanded tobacco having an OV content of 3% at a rate of 150

Ib tobacco per hour (about 68 kg / h), it has been found that at belt speeds that provide a delay time of about 40-80 minutes and air at a temperature of about 75-95'F (23.9-35 * C). and having a relative humidity at the inlet of from about 61% to about 64%, and air currents of about 1000 to 2500 ft3 / min (about 28, 3-70, 8 m3 / min.) achieve complete wetting without significant CV loss or measurable tobacco fracture using a modified Frigo-Scandia GCP 42 thread unit.

: Devices that can determine relative humidity over time, such as a Model 29-03 relative humidity and temperature recorder (manufactured by Rustrak Instruments Co., E. Greenwich, RI), are routed through a Frigoscandia unit to moisten tobacco. With these devices, it has been found that the relative humidity of the air is constantly increasing as the device moves up in the twist stack, with a relative initial humidity of about 35-45% at the bottom of the stack where tobacco is most dry and 62% relative humidity at the top of the stack most completely.

Figure 6 shows a typical curve where RH is plotted against time and obtained by the Rustrak unit. The percentage relative humidity of the air adjacent to the tobacco bed 15 103373 as a function of time is shown in Figure 6. Tobacco with an initial OV content of about 3% was introduced into a humidifying spiral unit and contacted with air having a relative humidity of about 43%. (point A in Figure 6). Figure 6 shows that as the tobacco advances in the humidifying coil unit, the relative humidity of the air adjacent to the tobacco increased from about 43% to about 62% at the outlet of the unit (point B in Figure 6). The OV content of the tobacco was about 11% upon exiting the wetting unit. The relative humidity of the air supplied to this humidifying spiral unit was adjusted so that the resulting humidified tobacco had no significant deterioration in CV.

Other means, such as the unit of Figure 4, for providing air of varying relative humidity may also be used to continuously implement the present invention. 4, tobacco is introduced into the unit from the tobacco inlet 40 to the conveyor 4 3 and exits through the tobacco outlet 41. Air of increasing relative humidity is blown upwardly or downwardly through the tobacco bed 42 in a plurality of zones 44, mimicking the gradual change in humidity achieved in the device of Figure 2. Such a gradual change in humidity could also be accomplished by moving air from a single source in a serpentine direction from right to left in Figure 4 so as to provide an airflow substantially opposite to the direction of tobacco movement. Thus, the air exiting a particular zone would be within the zone to the left of this zone; weather flow of air.

In carrying out the process of the present invention, it can handle whole dried tobacco leaves, cut or split tobacco, either expanded or unsweetened tobacco, or selected portions of tobacco such as stems or re-wetted tobacco. The method can be applied to any or all of the aforementioned tobacco products, with or without the addition of flavoring agents. In the particular case of tobacco drying, it has been found that the unexpanded and cut filler can be continuously dried at substantially ambient temperature through a substantially upstream flow modified Frigoscand self-stacking screw conveyor, from about 21% OV to about 15% OV hour you. In this case, air is led to the top of the unit at about 85 ° F (about 29.4 ° C) with a relative humidity of about 58%, and air exits the unit at about 77 ° F (about 25 ° C), with a humidity of about 68%. Drying was accomplished by little or no heat treatment of the tobacco.

Alternatively, the process of the present invention may be used to dry tobacco having a tobacco temperature significantly above ambient temperature, for example about 200-250'F (about 93.3-121.1'C). When the tobacco is dried within this temperature range, the relative humidity and temperature of the drying air are adjusted to provide suitable conditions for carrying out the process of the present invention.

· / Similarly to humidifying tobacco, it was now found that drying was best accomplished in the shortest possible time by setting the final moisture content of the air below that required to bring the tobacco to its desired final moisture content, thus the air-to-tobacco moisture gradient; increasing and thus increasing the force of force leading to drying. Unlike the wetting method, the final moisture content of the air stream can be maintained at a level much lower than the equilibrium level with tobacco at the desired OV level after drying.

17 103373

Experiment 1

In order to demonstrate the benefits associated with moistening dry expanded tobacco by slowly dispensing water as compared to moistening in a spray cylinder, a 20 gram sample of tobacco fill was placed in a sealed desiccator. This sample was saturated with liquid carbon dioxide and expanded in an expansion tower at 550 ° F (about 278 ° C). The OV content of this expanded tobacco sample was 3.4%. It was calculated that approximately 1.89 g of water would be needed to increase the OV content of the sample to 11.5%. This amount of water was placed in a small glass bottle with a rubber stopper through which a glass tube of 1/8 inch (about 3.2 mm) in diameter was passed. This bottle was also sealed in a desiccator. After nine days, the tobacco had absorbed all the water. The tobacco was then analyzed and found to have an OV content of about 11.5% as such. As used herein, the term "as such" means tobacco, prior to equilibration in an environmental chamber, with air having a relative humidity of 60% and a temperature of 75 'F (about 23.9 ° C) that is passed through the tobacco at low speed for about 24-48 hours. This balancing method is generally used to get the tobacco to the standard state prior to CV, SV, and sieve measurements. After this standardization, the desiccator's wetted tobacco had a CV of about 9.5 cm3 / g and a SV of about 2.9 cm3 / g, with an OV value of about 11.6%. For comparison, when another sample of this same tobacco was placed directly inside the equilibration chamber and wetted by equilibration under standard conditions, an equilibrium OV content of about 11.3% and CV and SV values of about 9.4 cm 3 / g and 2 , 7 cc / g, respectively. A third sample of this expanded tobacco filler was moistened in a spray cylinder so as to obtain an OV content of about 11.5% as such. After equilibration, this sample had a CV of about 8.5 cm3 / g and a SV of about 1.9 cm3 / g with an equilibrium OV concentration of about 11.6%.

As can be seen from the data in Table 1, a significant improvement in the equilibrium CV and the equilibrium SV was observed for the tobacco sample which had been moistened in the desiccator by slow addition of water, compared to the sample wetted by injection. Also, the CV and SV values of this sample were slightly improved compared to the sample directly equilibrated in the equilibration chamber.

Table I

As-Balanced Sample_OV,% SV, cm3 / q OV,% CV, cm3 / q SV cm3 / q

Tower 3.4 3.0 11/3 9.4 2.7 Output

Cylinder 11.5 1.8 11.6 8.5 1.9 1.9 Recorder

Desiccator 11, 5 2, 7 11, 6 9, 5 2,9

The second set of experiments was conducted using an environmental chamber to increase the moisture content of the expanded tobacco filler. A Paramter Generation and Control (PGC) chamber was used for this purpose. This chamber was equipped with a Micro-Pro 2000 microprocessor from Parameter Generation and; Control Inc., which made possible the controlled change of conditions inside the chamber.

Experiment 2

About 3 pounds (about 1.4 kg) of light tobacco, saturated with liquid carbon dioxide and expanded under conditions similar to those described in Experiment 1, were applied to the sheet in a layer of about 2 inches (about 5.1 cm). A plate with closed edges and a sieve bottom was placed all over the chamber. The sample was then wetted for a period of more than 1 hour using air having a temperature of about 75 ° F (23.9 ° C) and a relative initial humidity of about 36% and raising the final relative humidity to about 60%. The air was moving downward through the tobacco layer at a rate of about 45 19 to 103373 ft / min (about 13.7 m / min). This experiment was then repeated at 3 hour, 6 hour, and 12 hour intervals. The results shown in Table 2 show that, for increments of up to about 6 hours, the wetting rate does indeed affect the CV and SV values of the tobacco under these experimental conditions. The slower wetting occurs, the higher the observed CV and SV values. In addition, increasing the moisture content according to the present invention results in CV values of at least about 1 cm3 / g and SV values of at least about 0.2 cm3 / g compared to the corresponding values of tobacco moistened in the spraying cylinder. However, it has been found that most of this advantage is achieved by changing conditions over a period as short as about one hour.

Table 2

This is an apostasy

As such, in the environmental chamber _OV,% SV, cm3 / g_OV,% CV, cm3 / g

Tower Outlet 3, 10 3.06 11.33 9.71

Injection cylinder 11, 51 1.61 11, 37 8, 61

Conditions changed within 1 hour 10, 83 1, 85 11, 38 9, 72 3 hours 11, 44 1, 88 11, 36 9, 81: 6 hours 11, 45 1, 90 11, 30 9, 88 12 hours 11, 41 1, 97 11, 27 9, 89

Experiment 3

A laboratory study conducted in the experiment sought to determine both the rate of increase in humidity and the temperature; the effect of space on tobacco CV and SV values. Seven runs were conducted using tobacco saturated with carbon dioxide and expanded in an expansion tower at about 550 ° F (about 288 ° C). The moisture content of expanded tobacco was increased by the following methods.

(1) Tobacco was equilibrated for 24 hours in an ambient chamber having a relative humidity of 60% and a temperature of 75 ° F (about 23.9 ° C) by passing air through the tobacco at a speed of about 25 feet per minute. (about 7.6 m / min); (2) Water was injected to increase the OV content to about 7.5%, after which the tobacco was equilibrated for 24 hours under conditions of 60% relative humidity and 75 ° F as described in (1); (3) Water was sprayed to increase the OV concentration to about 7.5%, followed by raising the moisture content to 1 µl of the Injection in the cylinder; (4) Water was injected to a concentration of about 7.5% OV, followed by humid air with a relative humidity increased from about 46% of the initial value to about 60% of the final value; and (5) The moisture content was increased with humid air, the relative humidity of which was increased from about 46% to about 60%.

The increase in humidity in humid air was carried out in a PGC environmental chamber equipped with a microprocessor capable of controlling changes in conditions over a period of time. The following conditions were selected: (1) Magnification Time: 30, 60 and 90 minutes; (2) Air temperatures: 75 'F and 95 * F (about 23.9' C and 35 * C); (3) Air speeds: upwards through the tobacco layer at approximately 45 ft / min (approximately 13.7 m / min) and down through the tobacco layer at approximately 175 ft / min. (about 53.3 m / min); and (4) tobacco layer thickness: 2 inches (about 5.1 cm).

The tobacco used in all the wetting operations except the wetting in the spray cylinder had been obtained from the outlet of the tower after expansion and was enclosed in double plastic bags prior to wetting. The tobacco was then cooled from about 200 ° F (about 93.3 ° C), which was the temperature of the tobacco at the outlet of the expansion tower, to ambient temperature before changing the moisture content. When the moisture content was increased by changing the conditions at about 95 ° F (about 35 ° C), the tobacco still in the sealed bags was sufficiently heated to avoid condensation upon exposure to humid air prior to being subjected to changing conditions. The results related to these times are shown in Tables 3a-3e.

Table 3a Sample As-Equilibrated _OV,% SV, cm3 / g OV. % cv, cm3 / g X Tower Outlet 3, 43 3, 02 11, 31 9, 04 S Using Syringes Only 8, 06 2, 14 11, 68 8, 66 C Using Syringes and Cylinder 11, 53 1, 81 11, 59 8, 59 F With syringes and changing conditions 90 min (46% RH -> 60% RH, 75 'F; about 23.9 * C) 11, 27 1, 87 11, 51 9, 01 H With syringes and changing under conditions 90 min (46% RH -> 60% RH, 75 * F; about 23.9 * C) 10.96 l, 98 11, 36 9, 48 l Sample H was held for 15 minutes at 60%. RH, 75 * F 11, 54 1, 95 11, 56 9, 40 J With syringes and treatment under changing conditions for 60 min (46% RH -> 62% RH, 95 * F; about 35 * C) 10, 37 2, 38 11, 28 9, 85 K Sample J was held for 15 min at 62% RH, 95 'F; about 35'C 11.17 2.26 11.22 9, 88

Table 3b 22 103373 Sample As-Balanced _OV,% SV, cm3 / g OV,% CV, cm3 / g X Tower Outlet 3.01 2.58 11.34 9.23 S Using Syringes Only 7.51 2, 13 11, 39 8, 87 C With syringes and barrel 11, 86 1, 59 11,64 8, 07 F With syringes and changing conditions 60 min (46% RH -> 60% RH, 75 'F; approx. 23.9 * C) 10.55 1, 64 11, 45 8, 86 G Sample F was held for 15 minutes at 60% RH, 75 'F 11.56 1.64 11.42 8.61 H With syringes and treatment under changing conditions for 30 min ( 46% RH -> 60% RH, 75 * F 10, 28 1, 97 11, 27 8, 99 I Sample H was held for 15 min at 60% RH, 75 * F. 11, 73 1, 82 11, 25 8, 61

Table 3C

23 103373 Sample As-Equilibrated _OV,% SV, cm3 / g OV,% CV, cm3 / g A Tower Output 1, 81 2, 78 11, 37 9, 23 B Treated for 60 min under changing conditions (46% RH -> 60% RH, 95 'F) 10.91 1, 86 11, 47 8, 86 C Treated for 60 min under changing conditions (46% RH -> 60% RH, 75' F) 10, 53 2, 02 11, 28 9, 20 D Treated for 00 min under changing conditions (46% RH -> 60% RH, 95 'F) 10.84 1, 99 11.45 8, 90 E With syringes 5, 39 2, 37 11, 25 8.71 F With syringes and directly for 30 minutes at 60% RH, 95 'F 10.80 1, 81 11, 27 8, 39 G With syringes and 60 minutes at changing conditions (46% RH -> 60% RH, 95 * F) 10, 66 1 , 85 11, 23 8, 65 H With syringes and handling 90 min variable; under conditions (46% RH-> 60% RH, 95 'F) 10.76 1, 82 11.24 8, 62 I With syringes and treating for 60 min under changing conditions (46% RH-> 60% RH, 75' F) 10 , 65 1, 90 11.23 8, 75 J Syringes and handle ·; 90 min in Variable: Conditions (46% RH-> 60% RH, 75 * F) 10, 57 1, 87 11, 38 8, 74 K With syringes and direct 30 min conditions at 60% RH, 75 * F 10, 73 1, 87 11, 22 8, 64 L With the help of syringes and cylinders 10, 98 1, 60 11, 39 8, 28

Table 3d 103373 24 Sample As-Balanced _OV,% SV, cm3 / g OV,% CV, cm3 / g

Tl Tower Outlet 2, 83 3, 01 11, 92 9, 46 T2 Exposed directly to conditions at 60% RH for 30 minutes, 75 - F 11, 24 2, 27 11, 77 9, 08 T3 Treated for 90 minutes at changing conditions (46% RH) -> 60% RH, 75 * F) 11, 08 2.24 11.83 9, 29 T4 Treated for 90 min under changing conditions (30% RH -> 60% RH, 75 'F) 9.77 2.39 11, 85 9.43 51 Rui s Gold 4.78 2.82 11.66 8.98 52 With syringes and placed directly for 30 minutes at 60% RH, 75 'F 11.10 2.19 11, 64 8, 89 53 With syringes and treatment for 90 min in changing conditions (46% RH -> 60% RH, 75 'F) 10, 54 2, 25 11.27 9, 05 54 With syringes and treatment in 60 min in changing conditions (46% RH -> 60% RH) , 75 * F) 10, 56 2, 22 11, 73 9, 03 55 With syringes and hand racks for 30 min in changing conditions (46% RH -> 60% RH, 75 * F) 9, 74 2, 29 11 , 67 9, 19 C With syringes and barrel 10, 48 1.95 11.81 8.80 „103373

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The data in Tables 3a-3e show that the CV value can increase by about 0.5 to 1 cm3 / g and the SV can increase by about 0.3 to 0.4 cm3 / g when moistened with cooled tobacco, i.e., tobacco having a temperature of 75 -95 'F (about 23.9-35 ° C), under variable conditions, compared to moistening hot tobacco exiting the expansion tower in a spray cylinder. It was found that, starting directly from the OV concentration at the outlet of the tower, the increase in moisture content under changing conditions was preferably accomplished by first spraying water to increase its OV content to about 7%, followed by further increasing the moisture content under changing conditions. No significant difference was found in the CV or SV values of the tobacco, regardless of whether the tobacco was humidified with humid air having a relative initial humidity of about 46%, or whether the tobacco was humidified by a source of about 30% relative humidity, or the tobacco was moistened under changing conditions for about 60 minutes or about 90 minutes. It was also found that the moisture content of the tobacco can be increased either by an air flow directed downwardly through the tobacco layer at velocities in the range of about 175 to 235 ft / min (about 53 to 72 m / min.) Or by an airflow directed upwardly through the tobacco layer. ft / min. (about 14 m / min.), with no significant difference between CV or SV. In addition, it was found that increasing humidity under changing conditions yielded equal or better CV and SV values compared to the procedure of placing the wetted tobacco directly from the expansion tower into an ambient chamber having a relative humidity of 60% and a temperature of 75 ° F (about 23.9 *). C). Finally, it was found that spraying water to increase the OV content to about 7.5%, followed by raising the moisture content in humid air, produced better CV and SV values compared to spraying and subsequently increasing the moisture content in the injection cylinder.

28 1 0 3 3 7 3

Experiment 4 In these conducted experiments, the effect of airflow and air velocity on tobacco entrainment, air ducting and tobacco compression was determined. These experiments were performed using PGC environmental chambers. The actual air flow in each chamber was about 500 ft3 / min. (about 14, 2 m3 / min.) Air flowed upward through the tobacco layer in one PGC chamber and down through the tobacco layer in the other chamber. Samples of tobacco having a depth of 2 inches (about 5.1 cm) were placed on top of open screen-based plates having a surface area of 5 "x 5 3/4" (approximately 12.7 cm x 14.6 cm) and 4 inch (about 10.1 cm) solid edges, these plates were placed on shelves in the ambient chamber, forced air through the samples by covering the empty area of the shelf with cardboard and sealing any gaps with air. The air velocity was varied by changing the number of sample containers The tobacco used in these experiments was carbon dioxide impregnated and expanded at about 550 ° F (about 288 ° C) .The tobacco was moistened in the first step by spraying water immediately after expansion to give an OV content of about 8%. during the period, the conditions inside the chambers were adjusted to a temperature of about 75 ° F (about 23.9 ° C) and an RH of about 60%. Air velocity was measured with both a wing anemometer (Airflow Instrumentation, Model LCA 6000, Frederick, Maryland) and a hot-wire anemometer (Alnor Instrument Company, Skokie, Illinois, Thermometer Model 8525). These gauges were placed directly above or below the sample to measure the velocity of up and down air, respectively.

With the upward flow of air, the tobacco was found to rise somewhat immediately after the airflow was started at as low as about 2 6 ft / min. (about 7.9 m / min.). Subsequently, small air channels formed and the tobacco settled. As a result of these channels, the air flow was found to be very uneven at various points in the tobacco bed (ranging from about 22-45 29 103373 ft / min, about 6.7-13, 7 m / min. With an average speed of about 26 ft / min., About 7 , 9 m / min). As the average velocity of the air flow increased, stronger channeling was evident, and with air velocity greater than 45 ft / min (about 13.7 m / min), heavy entrainment and "blowing" of tobacco was observed, followed by significant channeling of the tobacco layer.

As the air moved downward, a certain amount of compression and a corresponding decrease in the velocity of air passing through the layers were observed at all the velocities studied. This is shown in Table 4. At an output speed of about 192 ft / min. (about 58.5 m / min.), the depth of the tobacco layer was reduced by about 28% and, as a result, the velocity of air passing through the bed decreased to about 141 ft / min. (about 43 m / min). With an air departure speed of approximately 141 ft / min. or less, the tobacco layer was found to compress about half of what was found at an air velocity of 192 ft / min and the air velocity through the tobacco layer decreased much less.

Table 4

Effect of layer compression on air velocity through tobacco layer

Air Speed (ft / min) Pet Depth (Inches)

Start End Change%% Start End Change% 192 141 27 2 1, 45 28 161 144 11 2 1.65 18 141 133 6 2 1.70 15 104 98 6 2 1, 80 10 43 41 5 2 1, 90 5

From the experiments described above, it was found that the moisture content of expanded tobacco can be advantageously increased under the following variable conditions: (a) time: from about 60 minutes to about 90 minutes; (b) RH: from about 30-45% of the initial RH to about 60-64% of the final RH; (c) a temperature in the range of about 75-95 ° F (about 23.9-35 ° C); Air flow: upward at approximately 45 ft / min (approximately 14 m / min) and downward at approximately 235 ft / min (approximately 72 m / min).

Experiment 5

Approximately 150 lb / h (about 68 kg / h) of a mixture of light and dark ("Burley") tobacco impregnated with carbon dioxide according to the method described in the co-pending patent application of Cho et al., SN 07/717 067, and the mixture was expanded as described in the examples above, was passed through a cooling conveyor to lower its temperature from about 200 * F (about 93 * C) to about 85 * F (about 29.4 * C) before being fed to the modified Frigoscandia Model GCP 42 for self-stacking thread unit. The tobacco passed through this spiral unit from the bottom up. Air flowed from top to bottom in the unit, causing tobacco and air to move substantially upstream. In this way, the moisture content of the tobacco was gradually increased as the tobacco continuously absorbed water from the air. The OV of the tobacco entering the process was about 3% and the OV of the tobacco leaving it was about 11%. The balanced CV of the feed material was about 10.53 cm3 / g, while the balanced CV of the wetted material was about 10.46 cm3 / g, which shows that the filling power of the tobacco was not significantly reduced, i.e. no statistically significant decrease in filling power was observed in the process. In addition, there was no measurable reduction in tobacco particle size during this wetting process as determined by the sieve test.

Experiment 6

A number of experiments were conducted using different types of tobacco which had been expanded at different tower temperatures and the moisture content of which was increased by the process of the present invention. At each run, approximately 150 lb / h (about 68 kg / h) of tobacco, expressed as the weight of the wetted tobacco, was wetted in the modified Frigoscand self-stacking spiral unit described in Experiment 5. The temperature of the air supplied to the humidifier 31 103373 was set at about 85 * F (about 29.4 * C) and had a relative humidity of about 62%. The air leaving the humidifier typically had a temperature of about 90-95 * F (about 32-35 * C) and a relative humidity of about 40-45%. As can be seen from Table 5, the filling power of the tobacco wetted by the process of the present invention cannot be found to be significantly reduced.

32 103373

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Experiment 7

About 200 lb / h (about 91 kg / h) of light tobacco with an OV of about 21.6% was fed to the modified Frigoscandia unit described in Experiment 5, which served as a drying unit. The tobacco moved through the drying coil unit from the bottom up. Air flowed from top to bottom in the unit, causing tobacco and air to move substantially upstream. The tobacco was successfully dried to an OV of 12, 2% with a delay time of about 60 minutes, using air having an inlet temperature of about 95 ° F (about 35 ° C) and an inlet RH of about 35%. The temperature of the air leaving the drying unit was about 83 'F (about 28.3 * C) and RH about 62%. The temperature of the tobacco entering and exiting the drying unit was such that it could be touched with an estimated temperature of about 75 * F (about 23.9 * C), indicating that the tobacco had not undergone heat treatment during the process. The drying process did not change the balanced CV value of the tobacco. This special drying test was designed to minimize heat treatment. Similar drying results could be obtained using higher temperatures to achieve controlled heat treatment.

While the invention has been described and illustrated with particular reference to preferred embodiments, it will be apparent to one skilled in the art that the form and details of the invention may be varied in various ways without departing from the spirit and purpose of the invention.

Claims (28)

A method of increasing the moisture content of a hygroscopic organic material to a predetermined final level, the method comprising the stages of: a) forming a layer of organic material by placing organic material on a conveyor; b) transporting the organic layer layered on the conveyor along the weights of a spiral conveyor from a first portion of the conveyor to the exit portion of the conveyor, and c) contacting the organic material with an air stream which runs substantially countercurrent with respect to the organic material. route, characterized in that d) simultaneously with the transport stage at the exit part of the spiral conveyor, an air stream whose relative humidity approaches a first balanced relative humidity and whose presence the organic matter is balanced to the predetermined final level, the relative humidity of the The air stream supplied to the first part of the conveyor and the relative humidity of the air stream present in the exit part of the conveyor are determined in accordance with the moisture content of the organic material which is at said first part and at said outlet part respectively. if e) in relative relation to the route of the organic material, the countercurrent flow of air flows in a successive manner through the spirals of the coil conveyor in such a way that the organic material and the airflow are maintained close to a balance condition between the first part of the coil conveyor and its outlet part is dehydrated and the organic material is progressively hydrogenated as the air stream streams countercurrently relative to the organic material route until the desired moisture content of the organic material is reached. Process according to claim 1, characterized in that the balanced CV of the organic material after the stage (d) is not significantly lower than the organic material CV before the stage (b). Method according to claim 1, characterized in that the balanced CV of the organic material after the stage (e) is not significantly lower than the balanced CV of the organic material before the stage (c). 4. A process according to any one of claims 1-3, characterized in that the temperature of the organic material is lower than ca. 38 ° C before bringing it into contact with the air stream. Process according to claim 1, characterized in that the starting moisture content of the organic material is approx. 1.5-13% before the stage of contacting the organic material with the air stream. 6. A process according to claim 5, characterized in that the starting moisture content of the organic material is approx. 1.5-6% before the stage of contacting the organic material with the air stream. Process according to claim 1, characterized in that the desired moisture content of the organic material after the stage (s) is approx. 11-13%. 8. A process according to claim 1, characterized in that the humidity of the air stream which is in contact with the organic material is approx. 30-64% at a temperature approximately within the range of 21-49 ° C. 9. A method according to claim 1, characterized in that the temperature of the air stream is chosen so as to achieve a desired heat treatment of the organic material, while eating the selective humidity of the air stream is chosen so as to achieve an increase in the moisture content of the organic material. Process according to any of the preceding claims, characterized in that the organic material is tobacco. 11. A process according to claim 10, characterized in that the tobacco is expanded tobacco. A method of lowering the moisture content of a hygroscopic organic material to a predetermined final level, the method comprising the stages of: a) forming a layer of organic material by placing organic material on a conveyor; b) transporting the organic layer layered on the conveyor. the material along the weights of a spiral conveyor from a first part of the conveyor to the exit part of the conveyor; and c) contacting the organic material with an air stream which runs substantially countercurrent with respect to the organic material route, characterized in that d) at the same time as the transport stage at the exit part of the coil conveyor, provides an air stream whose relative humidity approaches a first balanced relative moisture and in whose presence the organic matter is balanced to a predetermined final level, determining the relative humidity of the air stream fed to the first portion of the conveyor and the relative humidity of the air stream located in the exit portion of the conveyor in accordance with the moisture content of the the material at said first part and at said exit part, and that in addition e) the flow of air flowing countercurrently in relation to the route of the organic material in a successive way through the spirals of the spiral conveyor in such a manner pouring between the first part of the coil conveyor and its exit part, the organic material and the air stream near or below a balance state, the organic material being progressively dehydrated and the air stream progressively hydrogenating as the air stream flows countercurrent in relation to the organic material route until achieved the desired moisture content of the organic material. Method according to claim 12, characterized in that the balanced CV of the organic material after the stage (d) is not significantly lower than the balanced CV of the organic material before the stage (b). 14. A process according to claim 12, characterized in that it further comprises a stage where before the stage (b) the organic material is preheated to a temperature approximately within the range 38-121 ° C. Process according to Claim 12, characterized in that the temperature of the organic material is lower than approx. 121 ° C before the stage where it is brought into contact with the air stream. 16. A process according to claim 15, characterized in that the temperature of the organic material is lower than approx. 38 ° C before the stage where it is brought into contact with the air stream. 44 103373 17. A process according to claim 12, characterized in that the moisture content of the organic material is approx. 11-40% for the stage where the organic matter is brought into contact with the air stream. 18. Process according to claim 12, characterized in that the relative humidity of the air stream in contact with the organic material is approx. 20-60% at a temperature approximately within the range of 21-49 ° C. 19. A method according to claim 12, characterized in that the temperature of the air stream is chosen so as to achieve a desired heat treatment. 20. A method according to claim 12, characterized in that the temperature of the air stream is chosen so that substantially no heat treatment is carried out at all. 21. A method according to claim 12, characterized in that the temperature of the air stream is approx. 24-121 ° C. 22. A process according to any one of claims 12-21, characterized in that the organic material is tobacco. 23. A method according to any of the preceding claims, characterized in that the tobacco is selected from the group of expanded or non-expanded tobacco, tobacco as whole leaves, cut or chopped tobacco, stalks, any moistened tobacco or any combination of these types of tobacco. 24. A method according to claim 1 or 12, characterized in that one continuously realizes the stage at which the organic material is brought into contact with the air stream using a spiral conveyor where the air stream moves along a path substantially countercurrent with respect to the material. movement. 45 103373 25. A method according to claim 1 or 12, characterized in that the stage at which the organic material is brought into contact with the air stream is realized using an air stream whose velocity is in the range of 0.23-1.22 m / s. 26. A method according to claim 1 or 12, characterized in that the stage at which the organic material is brought into contact with the air stream is realized by controlling the air flow either down-eaten or eaten through a layer formed of the organic material, or by the air stream is controlled bed down and up through a layer formed of the organic material. 27. A method according to claim 24, characterized in that the spiral conveyor comprises a stack formed by a plurality of planes and that the air stream flows substantially through this stack by flowing successively in consecutive sequences. 28. A method according to any of the preceding claims, characterized in that the air stream flows substantially downstream from the top of the stack to the bottom of the stack and: that the spiral conveyor transports material upstream from the bottom of the stack to its top.