Tobacco – Tobacco treatment – Puffing
Reexamination Certificate
2002-06-03
2004-12-28
Walls, Dionne A. (Department: 1731)
Tobacco
Tobacco treatment
Puffing
C131S291000, C131S300000, C131S302000, C131S304000, C131S290000
Reexamination Certificate
active
06834653
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method and apparatus for expanding foodstuffs and luxury foodstuffs/tobacco materials. In particular, the method and apparatus in accordance with the invention may serve to increase the filling capacity of tobacco material or smoking materials reduced in size.
Concerning tobacco material, what should be understood as being included under the term tobacco material or smoking materials reduced in size are threshed tobacco leaves, tobacco stems, tobacco stalks, each cut or shredded, reprocessed tobacco as well as by-products of tobacco such as winnowings in tobacco processing (primary) and in cigarette production and packaging (secondary).
2. Description of Prior Art
Freshly harvested green leaves of tobacco contain a relatively high proportion of water, the residual content of which is reduced by means of various curing methods to less than 10% by mass. The water content is defined as the loss in mass of the tobacco relative to a moisture weigh-in in % by mass in a drying cabinet in a drying time of 3 hours at 80° C. (so-called Salvis moisture). Tobacco prepared as such constitutes raw materials, termed raw tobacco, employed in making e.g. cigarettes or other tobacco-based luxury foodstuffs. The processing chain involved from green leaf up to raw tobacco results in heavy shrinkage, this reduction in volume has a disadvantageous effect on the so-called filling capacity.
The tobacco industry describes filling capacity as the ability to produce finished products (e.g. cigarettes) using as little mass as possible, yet, which are physically stable, firm or hard. (filling capacity also is defined as the remaining volume relative to the weigh-in in ml/g which is derived from compression with a 3 kg weight in a cylindrical vessel after time available of 30 seconds).
Physical and chemical procedural principles are known technically for reversing the shrinking process:
The physical procedures (gaseous change in phase by heat supply) differ substantially by the impregnation means/expanding agent and thus by the change in phase, examples of which are impregnation with CO
2
(solid to gaseous change in phase), impregnation with liquid gas (liquid to gaseous change in phase) as well as impregnation with high-pressure N
2
(dissolved to gaseous change in phase).
Also to be mentioned in this respect are the methods proposed with organic solvents in liquid form and expulsion as gas, this describing substantially all known low-boiling methods.
The variants of the chemical procedures (generating a gas by thermal decomposition or exothermic reaction) differ substantially by the way the gas reacts in being generated, such as decomposing additives by introducing heat in the dryer or by the addition of further additives to trigger a reaction. Examples of this are impregnating with NH
3
/CO
2
(solid to gaseous thermal decomposition) with H
2
O
2
(liquid to gaseous thermal decomposition) and with N
2
H
4
/H
2
O
2
(liquid to gaseous exothermic reaction).
Only the physical methods have succeeded in gaining cost-effective significance, typical of which is pressurized impregnation. Subsequent expansion in the dryer is done after the so-called fixing instigated by reducing the pressure/cooling to atmospheric pressure in the impregnator to thus create an equilibrium substance at atmospheric pressure. The significance of these processes is explained by expansion being free of residues, low-cost expanding agents and an increase in volume in the order of magnitude around factor 2.
The drawback with these methods is the need to infeed extra additives and the necessity of a pressurized stage in the tobacco treatment process, impregnation normally being a complicated batch process.
The chemical procedures have gained no significance whatsoever due to the residue problems involved. In all known methods, the tobacco is impregnated either at or above atmospheric pressure with substances which, in a second step, e.g. in a dryer, are quickly put through a change in phase from solid or liquid state into a gaseous phase. This bloating effect results in the increase in volume of the tobacco structures. Known from DE 31 47 846 C2 is a method of enhancing the filling capacity in which the tobacco material is introduced into a carrier flow in a venturi nozzle, it thereby expanding. The drawback in this arrangement in the need to optimize the increase in filling capacity.
As regards the expansion of other foodstuffs and luxury foodstuffs/tobacco materials/tobacco materials capable of expansion (e.g. cereals or pulses; “puffs”), prior art mostly describes discontinuous methods and apparatuses; the following prior publications to be cited in this respect:
DE 195 21 243 describes a method and apparatus, wherein in batch operation a closed vessel is pressurized and the material contained therein heated. The upper portion containing no material is briefly exposed to increased pressure. By the vessel being abruptly opened, the material is output into an expansion chamber at atmospheric pressure. The increased pressure acts as an expansion agent, resulting in the water contained in the material being evaporated and causing said material to expand.
DE 195 21168 describes an apparatus and method analogous to those of DE 195 21 243 except that, in this case, the inner vessel features no holes in the upper portion containing no material.
DE 195 21167 describes an apparatus similar to that of DE 195 21 243 and DE 195 21 168, except that, in this case, the expansion chamber is rotatable and the expanded material is discharged longitudinally by rotation of the drum.
DE 198 06 951 describes an apparatus and a method for buffing a granular material, more particularly a preheat chamber for the material to be expanded. The heater employed comprises a fluidized bed chamber, in which the material is heated batchwise. With the aid of a branch circuit, the product is transferred to the buffing reactor.
Described in DE 198 06 950 is an expansion chamber configured two-part. The first part begins directly at the discharge of the expansion chamber and has the configuration of an elongated slim cone, designed to result in a laminar flow. It ports into the second part in which normal pressure is attained at the latest. Here the flow is turbulent.
Also in the case of this prior art, expansion can still not optimally occur and the systems operating in discontinuous batch operation are complicated and not very effective.
SUMMARY OF THE INVENTION
The object of the present invention is to overcome the aforementioned disadvantages of prior art, the intention being more particularly to effectively make optimum expansion possible and, as regards the tobacco material, it is intended that the cited reduction in the filling capacity/shrinkage is to be counteracted as much as possible.
This object is achieved in accordance with the invention by the subject matter of the independent claims. Preferred embodiments of the invention read from the sub-claims.
The invention makes it possible to attain, in the field of tobacco processing, increases in the filling capacity, not achievable up until now, and which, after expansion, are as much as 10 percent above the values for usual methods of expansion hitherto generally deemed optimized. The positive effects on the cost-effectiveness in producing smoking products are enormous in view of the amounts of tobacco material used in the industry. Corresponding benefits materialize in the area of other expandable foodstuffs and luxury foodstuffs/tobacco materials.
In the method in accordance with the invention the material continuously passes through a zone of elevated pressure, followed by a zone of reduced pressure before ending up in a zone of atmospheric pressure.
The core principle of the method exploits the ability of gases and vapors to totally convert compression energy by means of a nozzle into kinetic energy (in the extreme case, reducing pressure down to 0 bar). This extreme reduction in pressure can only be achieved when at the narrowe
Pluckhahn Frank
Schmekel Gerald
Weiss Arno
British American Tobacco (Germany GmbH)
Middleton & Reutlinger
Salazar John F.
Walls Dionne A.
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