Note: Descriptions are shown in the official language in which they were submitted.
CA 02398951 2002-08-06
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METHOD FOR IMPROVING THE FILLING ABILITY
OF TOBACCO
The invention relates to a method for improving the fillabil-
ity of tobacco, as cut tobacco leaves or ribs and/or tobacco
additives, by treatment of the tobacco material, which
initially has up to 15 wt.% moisture with a treatment gas con-
sisting of nitrogen and/or argon at pressures of 50 to 1,000
bar with continuous or graduated compression followed by con-
tinuous or graduated decompression, in which the compression
or decompression stages take place in either an autoclave or
with cascade-type switching in several autoclaves, followed by
thermal after-treatment of the tobacco material discharged.
Methods of this kind, which are also known as INCOM expansion
methods, have proved to be advantageous compared with the
pressure treatment of tobacco with carbon dioxide, ammonia or
volatile organic gases. Thus DE 31 19 330 A1 describes such an
expansion method with operating temperatures of 0 to 50°C pre-
vailing in the autoclave, wherein to increase the fillability
or the degree of expansion, use of a tobacco material with
moisture of up to 15 wt.% and after-treatment with water
vapour was provided. In this case the aim was that lower
moisture of the tobacco of 10 to 15 wt.% would lead to a
desired greater cooling of the tobacco material to be dis-
charged when the tension was released.
Furthermore, DE 34 14 625 C2 discloses a cascade method,
according to which, by the most widely varying measures such
as cooling of the treatment gas before loading of the reactor,
cooling of the autoclaves or use of an undercooled and
liquefied treatment gas, a low operating temperature is to be
effected during impregnation of the tobacco. It is true that
the tobacco moisture may lie anywhere, for instance within the
range of 10 - 30 wt.%, however it is expressly required that
the autoclave temperature and/or its cooling water temperature
must not exceed 50°C.
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This is also confirmed according to DE 39 35 774 C2 in con-
nection with a cascade-type expansion method, in which circu-
lation of the treatment gas via a cooler is provided, in order
to keep to the necessary low impregnation temperatures of 25
or 45°C.
Although good values have already been achieved with the
aforementioned expansion methods with regard to increasing the
fillability of tobacco and/or the degree of expansion, these
are relatively expensive because of the necessary cooling of
the autoclave or autoclaves and because of the additional
cooling of the treatment gas.
The aim of the invention is to improve the existing INCOM
methods and with equally good or better values with regard to
fillability or expansion effect, to avoid the uneconomical
cooling measures during compression which have hitherto been
regarded as necessary.
According to the invention a method of the type initially
mentioned according to the preamble to the patent claim, is
therefore proposed, which is characterised by the fact that
the compression is carried out at a reactor temperature of
above 55°C.
Surprisingly it has transpired that in the case of low tobacco
moistures within the range of up to 15 wt.% the existing
theory, which requires a low treatment temperature, does not
lead to optimum expansion results. On the contrary, only by
increasing the treatment temperature during compression was it
possible to achieve surprisingly good values with regard to
the expansion effect and/or fillability.
Furthermore, according to the method, this leads to the
advantage, that the heat of compression does not have to be
eliminated, and thus no additional cooling of the autoclave or
autoclaves is necessary.
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In the following example, the method according to the
invention is explained in comparison with the existing state
of the art. The test results show the differing influence of
the operating temperature on the degree of expansion for
different tobacco moistures. According to the existing theory,
in the case of tobacco moisture of 18 wt.%, increasing the
operating temperature above 40°C leads to a deterioration in
the expansion effect. On the other hand, in the case of
tobacco moistures of below 15 wt.%, clear improvements appear
if the high pressure treatment is carried out at operating
temperatures of 60 and 80°C. Surprisingly the achievable
degrees of expansion with low tobacco moisture and higher
operating temperatures are even in some cases above the values
achieved under conventional conditions.
Example
The high pressure treatment was carried out in a laboratory
autoclave with a used content of 2 1. A casing for circulation
of liquid media was used to adjust the desired operating
temperatures. The build-up of pressure was carried out from
below, the reduction in pressure upwards. Several valves made
the intended circuit diagrams possible. A compressor was used
to adjust the final pressure. A thermocouple element measured
the tobacco temperature in the upper tobacco filling section.
The laboratory device for thermal after-treatment consisted of
a permeable wire gauze serving as a conveyor belt, baffles for
formation of the tobacco mat in the desired width, a steam
nozzle with slit-type outlet and a steam suction device
arranged under the belt. The after-treatment was carried out
with saturated steam.
The most important treatment parameters are shown by the
following Table 1.
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Table 1
High ressure Thermal after-treatment
treatment
Gas supply from below Steaming about 10 kg/h
ca acit
Gas outlet a wards Slit nozzle about 8 mm
Tobacco 300 g Slit width about 160 mm
antit
Tobacco PVC pipe/ Transport about 5 cm/s
container perforated
bottom
The tobacco samples were spread out in flat plastic trays and
conditioned in the standard climate at 21°C and 62% relative
humidity. The fillabilities were determined using a Borgwaldt
density meter, and the specific volume in ml/g converted for a
nominal moisture of 12 wt.% and a nominal temperature of 22°C.
From the data of the untreated comparison/base specimens and
the expanded specimens, the relative improvement in
fillability, which is also described as the degree of
expansion, can be calculated according to the following
formula, in which FH means the fillability of the base and FE
means the fillability of the expanded tobacco:
d °s = (Ffi - FH) * loo% / FB
The tests were carried out with tobacco moistures of 8, 12 and
14 and 18 wt.% as a comparison. The operating temperatures
were adjusted by thermostatic control to 40, 60 and 80°C. The
final pressure amounted to 700 bar, the pressure reduction was
carried out in a time interval of approx. 0.5 min. All the
tests were based on a uniform mixture of Virginia tobaccos and
the after-treatment method with saturated steam described.
The results of the tests are represented in the following
Table 2, and those of the comparative test in the following
Table 2a. In the tables T" means the tobacco temperature
immediately before removal from the autoclave as discharge
temperature and O % means the relative improvement in
fillability and/or degree of expansion.
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Table 2
Operating temperatureTobaccomoisture8Tobaccomoisturel2Tobaccomoisturel4
C urt.% vvt.% urt.%
TA oC a % TA oC D % TA oC D
40 -61 59 -53 70 -48 76
60 -48 70 -25 79 -18 83
80 -15 78 -3 81 0 73
Table 2a
Operating temperature ° C Tobacco moisture 18 wt.~°
TA o C 0
40 -41 80
60 -12 76
80 1 54
Comparison of the above tables clearly shows the positive
effect o~ higher operating temperatures of 60 and 80°C on the
improvement of fillability, if tobacco with moistures of less
than 15 wt.s is used.
