U.S. patent number 3,575,178 [Application Number 04/806,967] was granted by the patent office on 1971-04-20 for a process for increasing the filling capacity of tobacco.
This patent grant is currently assigned to R. J. Reynolds Tobacco Company. Invention is credited to Grant Mathews Stewart.
United States Patent |
3,575,178 |
Stewart |
April 20, 1971 |
**Please see images for:
( Certificate of Correction ) ** |
A PROCESS FOR INCREASING THE FILLING CAPACITY OF TOBACCO
Abstract
A process of increasing the filling capacity of tobacco is
provided in which tobacco and an impregnating organic liquid are
contacted in one zone and contact of the tobacco with vapors of the
liquid is continued in another zone until the tobacco is thoroughly
impregnated. The impregnation is carried out at moderately elevated
temperatures and pressures. After impregnation is substantially
complete, the tobacco is withdrawn from the impregnating zone and
immediately heated at a reduced pressure to an elevated temperature
whereby expansion occurs. The heating is effected in a stream of
circulating hot gas from which the tobacco is separated and the gas
including vapors of the impregnating liquid are heated and
recycled. The flow of impregnating fluid to the impregnating zone
is controlled by the liquid level of the body of liquid
impregnating fluid maintained in the impregnating zone.
Inventors: |
Stewart; Grant Mathews
(Winston-Salem, NC) |
Assignee: |
R. J. Reynolds Tobacco Company
(Winston-Salem, NC)
|
Family
ID: |
25195248 |
Appl.
No.: |
04/806,967 |
Filed: |
April 13, 1969 |
Current U.S.
Class: |
131/296;
131/901 |
Current CPC
Class: |
A24B
3/182 (20130101); Y10S 131/901 (20130101) |
Current International
Class: |
A24B
3/18 (20060101); A24B 3/00 (20060101); A24b
003/18 () |
Field of
Search: |
;131/140--146,17,133--136 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
AP.C. application of Joachim Bohme Ser. No. 304,214 published May
11, 1943 (ABANDONED).
|
Primary Examiner: Rein; Melvin D.
Claims
I claim:
1. A process of increasing the filling capacity of tobacco which
comprises:
a. maintaining a tobacco impregnating zone containing an organic
fluid having a boiling point less than that of water under a
superatmospheric pressure sufficient to provide a body of said
fluid in the liquid state in a lower portion of said zone and an
atmosphere of said fluid in the vapor state in an upper portion
thereof,
b. passing water-moistened tobacco into said liquid state body in
said lower portion and then conveying said tobacco from said body
into said atmosphere in said upper portion, the residence time of
said tobacco in said zone being sufficient to impregnate said
water-moistened tobacco with said organic fluid,
c. withdrawing portions of said water-moistened and impregnated
tobacco from the upper portion of said zone to a zone of pressure
less than that obtaining in the impregnating zone, and
d. thereafter immediately contacting the so withdrawn portions with
a stream of a hot gas at an elevated temperature in an amount
sufficient to expand the tobacco contained therein.
2. The process of claim 1 wherein organic fluid is added to said
impregnating zone to replenish the organic fluid withdrawn with the
tobacco.
3. The process of claim 1 in which the expanded tobacco is
separated from said gas and vapors.
4. The process of claim 1 in which the organic fluid is essentially
immiscible with water.
5. The process of claim 4 in which the fluid is a fluorocarbon.
6. The process of claim 5 in which the fluorocarbon is
trichloromonofluoromethane.
7. The process of claim 1 in which the temperature of the hot gas
is at least about 200.degree. F. higher than the boiling point of
the fluid.
8. The process of claim 1 in which the tobacco passed into said
liquid state body is shredded tobacco.
9. A process of increasing the filling capacity of tobacco which
comprises:
a. maintaining a tobacco impregnating zone containing an organic
fluid having a boiling point less than about 180.degree. F. at a
temperature between the atmospheric pressure boiling point of the
fluid and 180.degree. F. and under a superatmospheric pressure
sufficient to provide a body of said fluid in the liquid state in a
lower portion of said zone and a saturated vapor atmosphere of said
fluid in an upper portion thereof,
b. passing tobacco beneath the surface of said body within said
zone to wet the tobacco with said liquid,
c. thereafter passing the wetted tobacco to the upper portion of
said zone whereby excess liquid drains away from the wetted
tobacco, the residence time of said tobacco in said zone being
sufficient to substantially completely impregnate same with said
fluid,
d. withdrawing the drained and impregnated tobacco from the upper
portion of said zone, and
e. thereafter immediately subjecting the so withdrawn tobacco to an
elevated temperature and a reduced pressure sufficient to expand
said tobacco.
10. The process of claim 9 wherein the tobacco treated is shredded
tobacco.
11. The process of claim 9 wherein said last mentioned elevated
temperature is above the boiling point of water at said reduced
pressure.
12. The process of claim 9 wherein the tobacco passed into the
impregnating zone has a moisture content of between about 10 and 30
parts by weight of water per 100 parts by weight of tobacco.
13. The process of claim 9 wherein the last-mentioned heating step
is effected by passing the tobacco into a stream of hot gas and the
expanded tobacco is thereafter separated from said stream.
14. The process of claim 13 is which the gas separated from the
expanded tobacco includes a substantial percentage of vapors of the
organic fluid and at least a portion of which provides the stream
into which the tobacco is passed from the impregnating zone.
15. A process of treating tobacco which comprises
a. passing a stream of an organic fluid having a boiling point less
than about 180.degree. F. into a tobacco impregnating zone,
b. heating said zone to a temperature above the atmospheric
pressure boiling point of said fluid but below about 180.degree. F.
under pressure sufficient to maintain a body of said fluid in the
liquid state in a lower portion of said impregnating zone and a
saturated vapor atmosphere of said fluid in an upper portion
thereof,
c. passing a stream of tobacco having a moisture content of between
about 10 and 30 parts by weight of water per 100 parts by weight of
tobacco (dry basis) into said liquid body in the lower portion of a
tobacco impregnating zone,
d. moving the organic liquid wetted tobacco to the upper portion of
zone whereby excess liquid drains from the tobacco and returns to
said lower portion,
e. withdrawing the drained and impregnated tobacco from the upper
portion of said impregnating zone,
f. immediately contacting the so withdrawn tobacco with a stream of
hot gas at a pressure less than that prevailing in said
impregnating zone and at a temperature above the boiling point of
water at said last-mentioned pressure,
g. separating the resulting expanded tobacco from said hot gas
stream, and
h. recycling at least a portion of said hot gas stream as the
stream for contacting the tobacco withdrawn from said contacting
zone.
16. The process of claim 15 wherein the temperature at which the
hot gas stream and tobacco are contacted is between about
250.degree. and 400.degree. F. and the time of contact is
sufficient to expand the tobacco but insufficient significantly to
impair the smoking qualities thereof.
17. The process of claim 15 wherein the temperature within said
impregnating zone is between about 100.degree. and 170.degree. F.
and the organic fluid is trichloromonofluoromethane.
18. The process of claim 15 in which the flow of said stream of
organic fluid into said impregnating zone is controlled by the
liquid level of said liquid body in the lower portion of said
impregnating zone.
Description
This invention relates to a process of treating tobacco and has for
an object the process for increasing the filling capacity of a
tobacco product.
Tobacco leaves when harvested contain a considerable quantity of
water and during the normal tobacco curing process this water is
removed by drying resulting in shrinkage of the leaf structure. In
the usual process of preparing tobacco for storage and subsequent
cigar or cigarette manufacture, the tobacco regains very little, if
any, of the shrinkage resulting from the drying step so that a
significant loss in the filling capacity of the tobacco is the
result. Thus, the cured tobacco has a bulk density which is in
excess of that required for making satisfactory cigarettes or
cigars. Also, during cutting of leaf or strips for making cut
filler for cigarettes, frequently the shreds are laminated together
to form hard, dense particles which occupy far less volume than the
original shreds occupied. This is wasteful since these hard
compacted shreds are not necessary in a smoking product to produce
a satisfactory article.
Several procedures have been suggested in the prior art for
increasing the normal filling capacity of dry or cured tobacco.
Certain of these procedures have involved puffing operations in
which the tobacco is subjected to high pressure steam, followed by
sudden release of pressure. Also, it has been suggested that the
filling capacity of tobacco may be increased, (i.e., bulk density
reduced) by exposing the tobacco particles or fibers to the vapors
of an organic liquid or to an organic liquid followed by air drying
at ordinary temperatures. However, these prior procedures have not
been wholly satisfactory either because they are not effective for
expanding the filling capacity to any great extent or they result
in shattering of the tobacco structure and particles so that
considerable waste incident to the formation of fines results.
In the copending application of James Donald Fredrickson, Ser. No.
720,406, filed Apr. 10, 1968, now Pat. No. 3,524,451, dated Aug.
18, 1970, there is disclosed a process of increasing the filling
capacity of tobacco which involves contacting the tobacco with a
volatile organic liquid to thoroughly impregnate the tobacco and
thereafter passing a heated gas into contact with the tobacco
whereby the tobacco is expanded and the liquid is separated
therefrom in the vapor state. An improvement in the Fredrickson
process is described in Moser and Stewart application Ser. No.
720,068, filed Apr. 10, 1968 now Pat. No. 3,524,452, dated Aug. 18,
1970. This latter application discloses a procedure in which a
moist tobacco thoroughly impregnated with a volatile organic liquid
is passed into a stream of a hot gas at a temperature between about
250.degree. F. and about 400.degree. F., whereby the tobacco is
expanded and is recovered from the hot gases.
Accordingly, another object of this invention is the provision of a
tobacco treating process which represents an improvement over the
processes disclosed in the copending Fredrickson and Moser and
Stewart applications above identified.
A further object of this invention is the provision of a process
for increasing the filling capacity of tobacco under conditions
such that the process can be readily controlled to produce the
desired product.
A still further object of this invention is the provision of a
process for increasing the filling capacity of tobacco in which the
time required for the preliminary impregnation with the organic
liquid is reduced.
An additional object of this invention is the provision of a
process which is essentially continuous and may be readily
controlled so that there is no net extraction of flavorants or
aroma producing materials from the tobacco during the impregnation
step.
A still further object of this invention is the provision of a
process whereby the flow of impregnating fluid into the
impregnating zone is controlled so that the impregnation will be
maintained uniform at all times.
A still further object of this invention is the provision of a
process which requires a minimum quantity of impregnating fluid to
effect the necessary impregnation before subjecting the tobacco to
the heating step.
Further and additional objects will appear from the following
description and the appended claims.
In accordance with one embodiment of this invention, a process is
provided in which an impregnating zone containing an organic fluid
having a boiling point less than that of water is maintained under
a superatmospheric pressure sufficient to provide within the zone a
body of said fluid in the liquid state in a lower portion and an
atmosphere of said fluid in a vapor state in the upper portion.
Tobacco, preferably moistened with water, is introduced into the
liquid-state body in order to wet it thoroughly with the organic
liquid and the thus-wetted and moist tobacco is then passed into
the atmosphere containing the vapors, the total residence time in
the impregnating zone, both liquid and vapor phase, being
sufficient so that the tobacco is substantially completely
impregnated with the organic fluid. After the impregnation has been
effected, the impregnated tobacco together with some of the organic
fluid is withdrawn from an upper portion of the pressurized
impregnating zone to a zone of lesser pressure and then immediately
subjected to an elevated temperature to cause the desired expansion
of the tobacco.
The tobacco to be treated in accordance with the process of this
invention is preferably a cured tobacco and may be in the form of
shreds, strips or leaves. However, the process is easier to control
and the best results are obtained if tobacco shreds are used. This
is for the reason that usually shreds are relatively easy to handle
in continuous procedures and the final product of the process need
not be subjected to shredding as may be necessary for cigarette
manufacture. Shredding of the final product would result in
compressing the product which would tend to destroy the ultimate
objective of the process of this invention, namely, to expand the
tobacco and eliminate compressed particles, as may have resulted
from prior treatment including shredding. Any type of tobacco may
be used in the practice of this invention and it is particularly
useful for the processing of burley, flue-cured and Oriental (e.g.,
Turkish) tobaccos.
As suggested in the copending Moser and Stewart application, it is
preferred that the tobacco subjected to treatment in accordance
with this invention be one that is moistened with water. The
presence of water moisture has been found to be desirable to soften
the tobacco particles to permit proper expansion when the tobacco
impregnated with the organic liquid is subjected to the elevated
temperatures. At low moisture levels or in the absence of moisture,
the tobacco when heated under expansion conditions tends to
disintegrate and form fines which are not desired in a product
which is to be used for the manufacture of cigarettes or cigars. If
the moisture level is too high the tobacco may be difficult to
handle and unnecessary expense may be incurred incident to the
vaporization of the excess moisture during the expansion step.
Preferably the tobacco to be processed in accordance with this
invention has a moisture content equivalent to between about 10 and
30 parts by weight of water per 100 parts by weight of tobacco (dry
basis). The moisture may be applied to the dried and cured tobacco
in any desired manner and it may be incorporated during customary
casing. It may be effected by spraying, wet steam treatment, or
otherwise, as will be obvious to one skilled in the art.
The organic liquid employed for impregnating the tobacco is one
which has a boiling point less than that of water at atmospheric
pressure and is chemically inert to the tobacco treated. The
organic liquid preferably has a boiling point at atmospheric
pressure less than about 180.degree. F. but at the same time the
boiling point is sufficiently high so that it may be readily
liquefied under the pressures readily obtainable in the
impregnation zone. Suitable organic liquids are the aromatic
hydrocarbons such as benzene; the ketones such as acetone and
methyl ethyl ketone; the ethers such as methyl ethyl ether, diethyl
ether, diisopropyl ether, methyl butyl ether and tetrahydrofuran;
the alcohols such as methanol, ethanol and isopropanol; the
aliphatic hydrocarbons such as pentane, isopentane, 2,2-dimethyl
butane, 2,3-dimethyl butane, and hexane; cyclo aliphatic
hydrocarbons such as cyclobutane; and halogen substituted aliphatic
hydrocarbons such as ethyl chloride, propyl chloride, isopropyl
chloride, butyl chloride, sec-butyl chloride, tert-butyl bromide,
methylene chloride, chloroform, carbon tetrachloride, ethylene
dichloride, and ethylidene dichloride; and the compounds generally
known as Freons such a trichloromonofluoromethane and
trichlorotrifluoroethane. Mixtures of the several solvents may also
be used and, if so, such mixtures are preferably azeotropic. The
preferred impregnating organic liquid is one which is substantially
immiscible with water and, for safety reasons, it is desirable that
the organic liquid be noninflammable. Freon-11
(trichloromonofluoromethane) has been found to be particularly
satisfactory.
As indicated, the tobacco impregnation preferably takes place in a
pressure vessel which is maintained at a superatmospheric pressure
and at a temperature such that a body or pool of the organic liquid
at about its boiling point is present in the lower section of the
zone and a saturated vapor atmosphere of the liquid is present in
an upper portion of the zone. In one form of the invention, the
impregnator takes the form of an elongated cylinder inclined to the
horizontal and equipped with a screw conveyor for moving moistened
tobacco from a lower portion of the impregnator into an upper
portion thereof. Tobacco and the organic fluid are introduced into
the lower section of the zone with the tobacco being introduced
directly beneath the surface of the liquid whereby it becomes
thoroughly wetted. The screw conveyor elevates the tobacco above
the surface of the body of liquid and into the vapor atmosphere,
during which process excess liquid drains back from the tobacco to
the liquid body in the bottom of the zone. During this procedure
and while the tobacco is moving upwardly to and through the upper
saturated vapor section, the impregnation continues so that by the
time it reaches the upper portion of the zone, the tobacco is
substantially completely impregnated with the organic fluid. In one
embodiment the elevated temperature of the impregnating zone is
maintained by suitable heat exchange jackets and pressure locks are
provided to permit the introduction and withdrawal of tobacco to
and from the impregnating zone such that loss of pressure does not
occur and a substantial continuous impregnating operation can be
achieved. Under the conditions of impregnation as thus described,
it has been found that substantially complete impregnation of the
tobacco may be accomplished in from 10 to 30 minutes, depending
upon the nature of the tobacco, the organic liquid employed, and
the temperature and pressure maintained within the impregnator. It
is preferred that the temperature of the tobacco in the impregnator
should be less than about 180.degree. F. since at higher
temperatures maintained for an extended period of time, the smoking
quality of the tobacco may be impaired. Preferably the temperature
ranges between about 100.degree. and 170.degree. F.
The substantially completely impregnated tobacco is then withdrawn
or discharged from the upper section of the impregnating zone
directly into a zone of reduced pressure (i.e., a pressure less
than that obtained in the impregnator) and immediately heated to an
elevated temperature above the atmospheric pressure boiling point
of water, preferably between 250.degree. and 400.degree. F. Usually
the temperature is in excess of 200.degree. F. higher than the
boiling point temperature of the impregnating liquid at said
reduced pressure. This immediate heating at reduced pressure causes
the tobacco to expand quite rapidly in order to effect the desired
increase in its filling capacity. It is important that the
impregnated tobacco be subjected to the pressure decrease and
temperature increase immediately upon discharge from the
impregnating zone since otherwise the vapors of the impregnating
fluid will slowly escape from the tobacco particles and laminations
without effecting the desired expansion. The time for heating is
generally less than 5, and suitably between 1 and 2, seconds
following the pressure release.
In a preferred form of the invention, the expansion heating step
for the impregnated tobacco is effected in a stream of hot gas into
which the tobacco is fed. The gas is first heated to the
appropriate temperature and the tobacco intermingled with it
whereafter it expands rapidly. As noted in the Moser and Stewart
application, this expansion is believed to occur within less than
about 4 seconds at 250.degree. to 400.degree. F., although the
process conditions and apparatus may be such that the tobacco
remains in contact with the heated gas for a somewhat longer
period. While temperatures of 250.degree. to 400.degree. F. are
indicated as preferable, it is desirable that the tobacco not be
maintained in contact with gases within this temperature range for
any substantial length of time since the smoking qualities of the
tobacco may become impaired.
After the expansion, the hot stream of tobacco and gases is passed
to a separator for removing the tobacco from the gases. The
separated gases, which may contain steam, air and a considerable
percentage of vapors of the impregnating liquid, are reheated to
the appropriate temperature and recycled for contact with
additional impregnated tobacco withdrawn from the impregnator. A
vapor side stream may be removed before reheating and passed to a
recovery system for separating water and air and for recycle of
impregnating fluid usually in the form of a liquid back to the
impregnator. The tobacco discharged from the separator is steam
stripped to remove all traces of the vapor of the impregnating
fluid and is then reordered to the desired moisture content,
usually 12 to 16 parts by weight of water per 100 parts by weight
of tobacco (dry basis). During reordering the tobacco may be
dressed and suitable flavorants may be added.
As above indicated, a feature of the invention is the provision of
a procedure in which the impregnator contains the impregnating
fluid in both the liquid phase and in the vapor phase. In the
embodiment here described, the tobacco is introduced under the
surface of the liquid phase of the fluid and the only withdrawal of
impregnating fluid is through the upper portion of the impregnator.
Inasmuch as the liquid drains back to the pool into which the
tobacco is introduced and after an initial startup of the process,
there is no net extraction of any flavorants or other
aroma-producing substances from the tobacco so that the expanded
product has essentially the same composition as the tobacco charged
to the process .
For a more complete understanding of this invention, reference will
now be made to the accompanying drawing which in diagrammatic form
illustrates an apparatus for carrying out the process of this
invention, In this embodiment shredded tobacco is passed by means
of a conveyor 10 to a moistener 12 in which the moisture content of
the tobacco, if necessary, is adjusted to between about 10 and 30
percent by weight dry basis. Suitably the moisture content is
adjusted to 16 to 18 percent by weight. Under certain conditions of
plant operation, the moisture content of the tobacco may already
fall within the prescribed range and, accordingly, the tobacco
charged to the process may bypass the moistener 12 by a conveyor 14
if desired. The moistened tobacco from the moistener 12 or the
bypass conveyor 14 or a confluence of both passes to a rotary star
valve 16 via conduit 18. The star valve serves to discharge the
tobacco at a prescribed rate into the lower portion of an elongated
impregnator 20.
The impregnator 20 is inclined at an angle (about 20.degree.) to
the horizontal and is provided with a motor-driven screw conveyor
22 by which the tobacco is moved from the lower portion of the
interior of the impregnator to the upper portion thereof. The
rotary star valve 16 prevents pressure release during the
introduction of tobacco into the impregnator thereby permitting a
suitable pressure to be maintained within the impregnator. The
selected organic liquid impregnating fluid is introduced into the
lower portion of the impregnator via conduit 24. The impregnator is
provided with an external jacket for receiving a heat-exchange
medium whereby the temperature of the tobacco and impregnating
fluid moving into and through the impregnator may be controlled
and, if desired, similar heat-exchange means (not shown) may be
provided in the shaft of the screw conveyor 22. The heat-exchange
means supplies the required heat of vaporization for the organic
fluid and in the upper section of the impregnator prevents
condensation of liquid which is not necessary or desired in that
portion of the equipment.
At the upper portion of the impregnator 20 there is provided a
discharge conduit 26, a pressure release rotary star valve 28 and a
conduit 30 which serves to discharge the impregnated tobacco
directly into a stream of hot gas circulating through a conduit 32
and a vertical expander 34 of enlarged cross section to a tobacco
separator 36 which may take the form of a conventional cyclone
separator. The rotary star valve 28 is arranged to discharge the
tobacco from the impregnator without materially affecting the
superatmospheric pressure maintained therein.
Tobacco is discharged from the bottom of the separator 36 through a
conveyor 38 to a steam stripper 40 in which any residual organic
fluid is separated from the expanded tobacco and conveyed through
line 42 to a conventional organic liquid recovery unit 44. Tobacco
from the stripper 40 is moved by conveyor 46 to a reorderer 48 from
which the final expanded tobacco product is discharged through a
conveyor 50. In the reorderer, sufficient water and sometimes
flavoring and dressing materials are added to provide the final
desired product.
Water and air are withdrawn through lines 52 and 54 from the
organic liquid recovery unit 44 and fresh organic liquid is fed to
the unit through conduit 56. A level control valve 58 is provided
in line 24 to regulate the flow of organic liquid to the
impregnator 20 in response to the level 60 of the pool or body 62
of the organic liquid maintained in the lower portion of the
impregnator. Organic fluid which may escape as vapor into the
rotary valve 16 or into the tobacco conveying conduit 18 may be
removed by fans or pumps 63 and 64 through conduits 66 and 68 to a
line 70 which may discharge either into the stream of gases moving
through conduit 72 from the upper portion of the separator 36 to a
gas heater 78 or may be passed to the organic liquid recovery unit
44. Vapors to be recovered from the system are passed from the
upper portion of the separator 36 through line 80 to the recovery
system 44.
As previously indicated, the preferred organic liquid for use in
accordance with this invention is trichloromonofluoromethane (i.e.,
Freon-11) having an atmospheric pressure boiling temperature of
approximately 74.degree. F. When this solvent is utilized the
tobacco having the appropriate moisture content is passed into the
impregnator 20 through the rotary valve 16 and deposited under the
surface 60 of the pool 62 of the Freon maintained in the bottom of
the impregnator. This liquid level is maintained during operation
by passing additional fluid to the impregnator through conduit 24
in response to the liquid level control valve 58. Heating fluid is
passed to the jacket of the impregnator 20 to supply the necessary
heat of vaporization for the organic liquid and to maintain the
desired temperature within the impregnator. Under these conditions
the Freon vapors generate a superatmospheric pressure which is
necessary to maintain the body or pool 62 of liquid in the lower
portion of the impregnator. The tobacco having been introduced
underneath the surface of the organic liquid is thoroughly "wetted"
and then elevated by the screw conveyor toward the upper portion of
the impregnating zone. During this process the tobacco emerges from
beneath the surface of the liquid and progresses upwardly through
an atmosphere of saturated vapor and any excess liquid drains back
to the pool 62. However, as the tobacco progresses upwardly through
the impregnator under superatmospheric pressure through the
saturated vapor atmosphere, impregnation of the tobacco continues
to occur until it is essentially complete at the time that it
reaches the upper portion of the impregnator. Thereafter the
tobacco is discharged through conduit 26 and the rotary valve 28 to
conduit 30 wherein the pressure is reduced to about atmospheric and
it is then passed immediately into a rapidly moving stream of hot
gases heated to above the boiling point of water, preferably
between about 250.degree. and 400.degree. F. and suitably
310.degree. F. The tobacco suspended in the hot gases passes
upwardly through the vertical expander 34 in which the tobacco is
expanded to provide the desired filling capacity and it is
thereafter separated from the vapors in the separator 36. The
separated gas comprising a mixture of air and water and Freon
vapors is then recycled through heater 78 and forced by fan 82 into
contact with a fresh charge of impregnated tobacco from conduit
30.
In Table I there is shown a material balance for one specific
operation carried out in the apparatus shown in the drawing. In
this specific operation the impregnating fluid employed is
trichloromonofluoromethane (Freon-11) and the temperature within
the impregnator is approximately 112.degree. F. at 15 pounds per
square inch gauge pressure. The volume of the impregnator 20 is
approximately 300 cubic feet, the volume rate of flow of hot gas in
the expander 34 is about 40,000 to 50,000 cubic feet per minute and
the interval of time between the release of pressure with tobacco
at the star valve 28 and its initial contact with the hot gas is
less than 1 second. The tobacco charged to the process is a
shredded flue-cured tobacco. ##SPC1##
The product obtained from the process after reordering to a
moisture content between about 11 and 13 parts by weight of water
per 100 parts by weight of tobacco (dry basis) in comparison with
the tobacco charged to the impregnator is one in which its filling
capacity has been expanded over 100 percent, as determined by the
method described in the Moser and Stewart application. Essentially
this method is as follows: A compressometer is used which is
essentially composed of a cylinder 9.5 centimeters in diameter with
a graduated scale on the side. A piston 9.4 centimeters in diameter
slides in the cylinder. Pressure is applied to the piston, and
volume in milliliters of a given weight of tobacco, 100 grams, is
determined. Experiments have shown that this apparatus will
accurately determine the volume (filling capacity) of a given
amount of cut tobacco with good reproducibility. The pressure on
the tobacco applied by the piston is 2.30 pounds per square inch
applied for 5 seconds, at which time the volume reading was taken.
This pressure corresponds closely to the pressure normally applied
by the wrapping paper to tobacco in cigarettes.
The product of the process is essentially free of compressed
laminated tobacco particles which are found incident to the initial
shredding of the tobacco used as a charge stock. The product may be
used to manufacture cigarettes in the conventional manner or it may
be mixed with other tobaccos to provide a desired blend for use in
the manufacture of cigarettes or other smoking articles.
While a particular embodiment of this invention has been described
in the foregoing, it will, of course, be apparent that other
modifications may be made without departing from the spirit and
scope of the appended claims.
* * * * *