SK286572B6 - Method for improving the filling capacity of tobacco - Google Patents

Abstract

The invention relates to a method for improving the filling capacity of tobacco, such as cut tobacco leaves or ribs, by treating the tobacco material comprising up to approximately 30 wt. % initial humidity with a treatment gas consisting of nitrogen and/or argon, at pressures of between 50 and 100 bars (5 and 100 Mpa), during continuous or graduated compression followed by continuous or graduated decompression. The compression and decompression is carried out either in an autoclave or in several autoclaves arranged in the form of a cascade. The invention is characterized in that the thermal aftertreatment of the extracted tobacco material is carried out by means of a flowing, heat-transferring medium consisting of a mixture of permanent gases and superheated steam, the proportion of permanent gas being kept constant at a value between 10 and 60 vol. %.

Description

The present invention relates to a method for improving tobacco filler according to the preamble of the main claim.

BACKGROUND OF THE INVENTION

For example, DE 31 19 330 A1, DE 34 14 625 C2 and DE 39 35 774 C2 have proven to be successful in improving the filler capacity of tobacco according to the INCOM method. In these processes, the tobacco, typically in the form of cut sheets or ribs, and with an initial moisture content of about 30% by weight, is subjected to continuous or stepwise compression by a process gas composed of nitrogen and / or argon at pressures of 50 to 1000 bar. followed by continuous or graduated decompression. The compression or decompression steps take place either in a single autoclave or in several cascaded cascades. The removed tobacco material is then subjected to an additional heat treatment in which the tobacco acquires volume and thus increases its filler capacity.

These INCOM processes have proven to be advantageous in comparison to methods of pressurizing tobacco with carbon dioxide, ammonia or volatile organic compounds, since in the case of volatile organic compounds it is necessary to cope with undesirable leaching of odorous substances or nicotine from the tobacco material; in the tobacco material with its taste and finally in the case of using carbon dioxide, the removal of dry ice resulting from decompression is energy consuming.

With reference to the aforementioned methods, INCOM DE 31 19 330 describes such an expansion process with prevailing operating temperatures in an autoclave of 0 to 50 ° C, assuming the use of tobacco with a moisture content of up to 15% by weight. and after-treatment with water vapor to increase filler or volume acquisition. Furthermore, patents DE 34 14 625 C2 and DE 39 35 774 C2 describe a cascade process in which a low operating temperature during tobacco impregnation is achieved by cooling the process gas before it is fed into the reactor, cooling the autoclave or using a supercooled or liquefied process gas.

In these known processes, the post-heat treatment is carried out with water vapor having a density of 0.5 to 10 kg / m ³ , preferably saturated vapor, or with hot air at temperatures up to 440 ° C.

From EP 484 899 B1, a method for treating tobacco with carbon dioxide at pressures of about 30 bar (3 MPa) is known, in which the post-heat treatment is carried out by introducing tobacco into high-temperature steam or into a gas containing 50 to 95% by volume. water vapor to heat the tobacco in the flow medium to 200 to 350 ° C, wherein water or steam at a lower temperature downstream of the tobacco inlet point is supplied to reduce the temperature of the flow medium. Thereafter, the tobacco is dried to about 2 to 3 wt. humidity to normal humidity. Since ice is formed after pressure treatment of the carbon dioxide after decompression, the tobacco must undergo rapid heat treatment despite the high enthalpy of dry ice evaporation, resulting in considerable thermal and / or mechanical stress on the tobacco.

In the case of the INCOM process on which the present invention is based, the nitrogen and / or argon treated tobacco have much lower energy requirements for desorption of absorbed gases and subsequent tobacco acquisition by volume than the CO ₂ treated tobacco, so that the INCOM process does not CO ₂ for negative effects on taste. In addition, in the post-heat treatment of the nitrogen- and / or argon-treated tobacco, the condensation of water vapor transfers heat to the cold tobacco, and in the further course of the post-heat treatment the desired moisture content in the expanded tobacco is achieved.

However, even with the INCOM method, there is a risk of overwhelming or overheating of the tobacco resulting in loss of filler due to the collapse of the expanded cell structure.

SUMMARY OF THE INVENTION

It is an object of the present invention to carry out a post-heat treatment of the nitrogen and / or argon treated tobacco using the INCOM process so as to achieve uniform product quality with optimum filler capacity.

To achieve this objective, a method according to the preamble of the main claim is therefore proposed, characterized in that the post-heat treatment is carried out by means of a flowing heat exchange medium consisting of a mixture of permanent gases and superheated water vapor, keeping the proportion of permanent gas constant at a value. 10 to 60% vol.

SK 286572 Β6

By permanent gas in this context is meant any gas which can be used together with water vapor such as air, optionally mixed with nitrogen and / or argon or other inert gases, for drying.

Surprisingly, it has been found that the proportion of permanent gas in the mixture with superheated water vapor is a critical parameter for achieving optimum filler values under given process conditions, especially in the jet drying process.

Preferably, air is used as a permanent gas, the proportion of air being indirectly controlled by measuring the oxygen content. The proportion of air in the flowing heat exchange medium is preferably in the range from 20 to 50% by volume. and in particular from 25 to 40% by volume.

The temperature of the heat transfer medium should preferably be between 120 and 300 ° C and the humidity of the tobacco after pressure treatment and before the post-heat treatment should be between 8 and 25 ° C. It is further desirable that after the post-heat treatment, the moisture content of the tobacco is 8 to 15% by weight.

In a particularly preferred embodiment of the process according to the invention, the process is such that, in the post-heat treatment, the hot steam is fed in a closed cycle according to the known jet drying principle, in which the permanent gas is fed downstream of the hot steam injection at the heat-treated tobacco collection point. In a closed cycle, it circulates with a greater amount of water vapor, maintaining the sustained fraction of the permanent gas after cooling the expanded tobacco and removing it. In particular, this achieves a rapid reduction in the temperature of the tobacco and thus a stabilization of its filler.

In the following, a preferred method of using conventional jet driers is explained with reference to the schematic representation of Figure 1, in which air was used as a permanent gas and its fraction was determined indirectly by measuring oxygen.

Due to the local pressure difference between the heat transfer medium and the surrounding area, outside air is drawn in at the inlet port 1 and outlet port 2 and the steam is discharged through the steam valve 3. The superheated steam is supplied by the steam valve 4. heat exchange medium. By actuating the steam valve 4 and the steam shutter 3, the desired oxygen content and thus a constant ratio of permanent gas to superheated steam is ensured.

Referring to the following embodiment, the relationship between filler and the proportion of permanent gas in the heat exchange medium is demonstrated. The proportion of permanent gas required in each individual case to achieve optimum filler capacity depends on the type and humidity of the tobacco material used and on the boundary conditions of the production equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a method of heat treating tobacco impregnated with oxygen and / or argon.

Fig. 2 shows the thermal treatment of tobacco by the INCOM method in a jet dryer together with a relative improvement in the filler capacity against the oxygen content of the heat exchange medium.

DETAILED DESCRIPTION OF THE INVENTION

Example

The tobacco treated with the jet dryer of Figure 1 in accordance with the INCOM method was post-heat treated as follows. The flow rate of the supplied tobacco was 1250 kg / h in quantity, the flow of circulating heat exchange medium consisting of superheated steam and air was 7,315 m ³ / h in volume terms. The proportion of steam and permanent gas deductible by measuring the oxygen content at constant dryer output varied from 1.3 to 7.5 and 15 vol%, depending on the oxygen content, which corresponded to a 6.5, 37 or 75 vol% permanent gas fraction. and a simultaneous change from 185 ° C to 165 ° C in the opposite sense of the initial temperature measured before the tobacco was introduced.

The filler capacity of the collected conditioned tobacco was determined by a Borgwaldt densimeter and the specific volume was converted to ml / g at a nominal moisture content of 12% by weight. and a nominal temperature of 22 ° C. The relative filler improvement was calculated in the following manner from the non-permanent gas base experiment data and from the expanded sample experiment with steam and permanent gas heat exchange media:

A% = (F _E -F _B ) x 100% / F _B (Fb = filler, baseline, steam without permanent gas, Fe = filler, expanded tobacco, steam with permanent gas).

The graph shows the relationship between the expandability of expanded tobacco and the process variable of the oxygen content in the heat exchange medium, as well as the possibility to determine the optimal process conditions using this process variable.

Claims (8)

A method of improving the filler of tobacco, for example cut tobacco leaves or ribs, by treating the tobacco material with an initial moisture content of up to about 30% by weight. process gas composed of nitrogen and / or argon at pressures of 50 to 1000 bar (5 to 100 MPa) under continuous or graduated compression followed by continuous or graduated decompression, both compression and decompression steps being carried out in a single autoclave or in several cascaded autoclaves, and then post-heat treatment of the removed tobacco material, characterized in that post-heat treatment is effected by a flowing heat exchange medium in the form of a mixture of permanent gases and superheated steam, while maintaining a constant gas content of 10 to 60% vol. Method according to claim 1, characterized in that air is used in particular as a permanent gas and the proportion of air is controlled by measuring the oxygen content. Method according to claim 2, characterized in that the nominal medium is 20 to 50% by volume. Method according to claim 2, characterized in that the nominal medium is 25 to 40% by volume. Method according to claims 1 to 4, characterized by 120-300 ° C. Method according to claims 1 to 5, characterized in that the tobacco is 8 to 25 wt. before additional heat treatment. Method according to claims 1 to 6, characterized in that the moisture content of the tobacco after the post-heat treatment is 8 to 15% by weight. Method according to claims 1 to 7, characterized in that, in the post-heat treatment, the hot steam is supplied in a closed cycle according to the jet drying principle, in which the permanent gas is fed downstream of the hot steam inlet at the withdrawal of the heat-treated tobacco and then in a closed cycle circulates with a greater amount of water vapor, while maintaining the stability of the permanent gas fraction upon cooling of the expanded tobacco and its removal.