PNEUMATIC CLASSIFIER FOR TOBACCO AND METHOD

DISPOSITIF PNEUMATIQUE POUR LE TRI DU TABAC, ET SON FONCTIONNEMENT

English Abstract

PNEUMATIC CLASSIFIER FOR TOBACCO AND METHOD
Abstract of the Disclosure
Intermixed light leaf and heavy stem
tobacco particles are fed or propelled inwardly and
across a vertical separator chamber of the
classifier while forced air is directed upwardly
through the intermixed particles and at varying vel-
ocities across the length of the separator chamber
to gently separate the leaf particles from the
heavier stem particles. The stream of intermixed
particles is projected across the separator chamber
at a variable initial velocity and the varying velo-
cities of the upwardly directed forced air streams
are correlated with the velocity of the stream of
particles being fed across the separator chamber to
gently separate the light leaf particles from the
heavier stem particles. An adjustable deflector
plate is supported adjacent the inlet feed for
varying the angular position of the feeding of the
stream of intermixed particles across the separator
chamber to thereby vary the classifying plane in
which the particles are projected across the separa-
tor chamber. A set of air pattern screens, with
openings of different sizes therein, is provided for
easy insertion and removal of the individual air
pattern screens in the separator chamber to control
the amount of forced air which passes upwardly
through the separator chamber.

Claims

-18-
The embodiments of the invention in which an
exclusive property or privilege is claimed are defined as
follows:



1. A vertical lift pneumatic classifier for
separating light tobacco leaf particles from heavier tobacco
stem particles, and being characterized by a single pass of
tobacco particles across a separation chamber, and being
adjustable for use with a full range of fed tobacco particle
sizes and shapes in a threshing system, said classifier
comprising:
a vertically extending separator chamber;
tobacco particle feed means located at a first end
of said separator chamber for projecting a dispersing stream
of intermixed light leaf and heavier stem particles across
said separator chamber from one end thereof toward another in
an unrestricted path;
leaf removal means disposed proximate an upper
portion of said separator chamber;
stem removal means located at a second opposite end
of said separator chamber, opposite said tobacco particle
feed means, and at an elevation below that of the tobacco
particle feed means;
a forced air distribution surface having a length
extending across the lower portion of said separator chamber
substantially from the chamber first end to the chamber
second end, said surface including openings permitting the
introduction of upwardly directed forced air from underneath
the surface and into the separator chamber for the purpose of
lifting and separating the tobacco leaf particles;


-19-
Claim 1 - cont'd ...



forced air supply means for directing forced air
upwardly through said air distribution surface and into the
separator chamber;
means associated with said forced air supply means
and said air distribution surface for establishing along the
length of said air distribution surface and from said first
end of said chamber to said chamber second end, a plurality
of upwardly directed air streams with varied velocities with
the higher velocity air streams being proximate the separator
chamber first end and the lower velocity air streams being
proximate the chamber second end, so that the velocity of the
respective upwardly directed forced air streams is correlated
with the decreasing velocity of the stream of leaf and stem
particles propelled across the separator chamber; and
means for selectively adjusting the tobacco
particle feed velocity and the angular orientation of the fed
particle stream with respect to the horizontal;
the velocities of the forced air streams being
adjustable independently of the velocity and angular
orientation of the particle stream in response to the
characteristics of the tobacco particles to provide, for all
tobacco particle characteristics, peeling off of a
substantial portion of the light leaf particles in an upward
direction proximate said first end and projection of the
heavier stem particles substantially along a descending path
across said chamber to said stem removal means.


-20-
2. A classifier as claimed in claim 1, wherein
said tobacco particle feed means includes a vaned rotor and
wherein said means for selectively adjusting the tobacco
particle feed velocity and angular orientation includes:
a variable speed drive for said vaned rotor; and
an adjustable deflector plate located immediately
downstream of said vaned rotor.



3. A classifier as claimed in claim 1, wherein
said means for establishing a progressively changing velocity
of forced air input comprises air pattern screen means
including openings sized to produce higher input air stream
velocities proximate the separator chamber first end and
progressively lower air stream velocities along the length of
said air distribution surface, with the slowest air stream
velocities being proximate the separator chamber second end.



4. A classifier as claimed in claim 3, wherein
said air pattern screen means comprises a frame supported for
easy removal and placement in said separation chamber, and
screen material fixed on said frame.



5. A classifier as claimed in claim 4, wherein
said screen material includes a plurality of zones along the
length thereof, and wherein the sizes of the openings in said
zones is varied from zone to zone.



-21-
6. A classifier as claimed in claim 1, including
air diffuser vanes for establishing the multiple streams.



7. A classifier as claimed in claim 6, wherein the
highest velocity air stream travels a shorter distance and
through a smaller volume than the lowest velocity air stream,
with any intermediate velocity air stream(s) travelling an
intermediate distance through an intermediate volume.



8. A classifier as claimed in claim 1, wherein
said means for establishing a plurality of air streams
provides an air stream velocity of about 800 feet per minute
in a first zone proximate said chamber first end, a second
air stream velocity of about 450 feet per minute in a second
zone intermediate the chamber first and second ends, and a
third air stream velocity of about 200 feet per minute
proximate the chamber second end.



9. A classifier as claimed in claim 1, wherein
said separator chamber second end includes an outwardly
curved wall (15) above the stem removal means, said curved
wall being so curved and so positioned as to approximate the
path of the heavier stem particles as they approach the
second end to encourage such particles to fall downwardly
into said stem removal means without disrupting the smooth
flow of particles through the chamber.


-22-



10. A classifier as claimed in claim 1, wherein
said forced air distribution surface is downwardly inclined
from the separator chamber first end to the chamber second
end at an angle on the order of about 30° with respect to
horizontal.



11. A vertical lift pneumatic classifier for
separating light tobacco leaf particles from heavier tobacco
stem particles in a single pass of combined tobacco particles
across a separation chamber, and being adjustable for use
with a full range of tobacco particle sizes and shapes in a
threshing system, said classifier comprising:
a vertically extending separator chamber;
a variable speed, vaned rotor located at a first
end of said separator chamber for projecting a stream of
intermixed light leaf and heavier stem particles across said
separator chamber from said first end toward a second end
thereof;
a leaf removal duct disposed proximate an upper
portion of said separator chamber;
a stem removal chute located at said second end of
said separator chamber, and at an elevation below that of the
vaned rotor;
a static, planar air distribution screen extending
at a downward incline across said separator chamber
substantially from the chamber first end to a point near the
stem removal chute at the chamber second end at an elevation


-23-
Claim 11 - cont'd ...



below said vaned rotor, said screen surface permitting the
introduction of forced air therethrough and into the
separator chamber for the purpose of lifting and separating
the tobacco leaf particles from said stem particles, the
openings of said screen being sized to provide greater air
velocities near the chamber first end and progressively lower
air velocities as the screen extends to the chamber second
end;
forced air supply means for directing forced air
through said air distribution screen and into the separator
chamber;
air diffuser vanes associated with said forced air
supply means for establishing multiple streams of inlet
forced air, with the highest velocity stream being proximate
the separator chamber first end, and with the lowest velocity
being proximate the second end of said chamber so that the
varied decreasing velocities of the forced air input streams
are correlated with the decreasing velocity of the stream of
leaf and stem particles propelled across the separator
chamber;
whereby the velocity of the fed tobacco particles
and the forced air velocities along said air distribution
screen are independently adjustable in response to the
characteristics of the fed tobacco particles to provide, for
all particle characteristics, peeling off of a substantial
portion of the light leaf particles in an upward direction


-24-



proximate said first end and projection of the heavier stem
particles substantially along a descending path to said stem
removal chute.



12. A classifier as claimed in claim 11 wherein
said screen includes a plurality of zones along the length
thereof, and wherein the sizes of the openings in said zones
are varied from zone to zone.



13. A classifier as claimed in claim 11 wherein the
highest velocity stream travels a shorter distance and
through a smaller volume than the lowest velocity stream,
with any intermediate velocity stream(s) travelling an
intermediate distance through an intermediate volume. :



14. A classifier as claimed in claim 11 wherein the
screen and air diffuser vanes are constructed to encourage a
forced air flow velocity proximate the chamber first end that
is on the order of four times higher than the forced air flow
velocity at the chamber second end.




15. A classifier as claimed in claim 11 wherein
said classifier provides an air input stream velocity on the
order of about 800 feet per minute in a first zone proximate
said chamber first end, a second air input stream velocity of
about 450 feet per minute in a second zone intermediate the


-25-
chamber first end second ends, and a third air input stream
velocity of about 200 feet per minute proximate the chamber
second end.



16. A classifier as claimed in claim 11 wherein
said separator chamber second end includes an outwardly
curved wall above the stem removal chute, said curved wall
being so curved and so positioned as to approximate the path
of the heavier stem particles as they approach the second end
to encourage such particles to fall downwardly into said stem
removal chute without disrupting the smooth flow of particles
through the chamber.



17. A classifier as claimed in claim 11 wherein
said air distribution screen is downwardly inclined from the
separator chamber first end to the chamber second end at an
angle on the order of about 30°.



18. A single pass tobacco particle classifier for
separating lighter tobacco leaf particles from heavier
tobacco stem particles and comprising:
a separator chamber having opposed ends, an upper
portion, and a lower portion;
means for projecting a combined dispersing stream
of light tobacco leaf particles and heavier tobacco stem
particles in an arc-shaped path across said chamber, from one


-26-



end toward another second end, with the velocity of said
stream decreasing as it approaches the second other end;
means for applying to said combined projected
particle stream a plurality of upwardly moving air streams
having differing velocities for gently separating lighter
tobacco leaf particles from heavier tobacco stem particles in
a single pass of said combined particle stream across said
air streams;
the higher velocity air streams engaging faster
portions of the combined particle streams proximate said one
end and across said projected particle stream and the lower
velocity air streams engaging slower portions of the combined
projected particle stream proximate said second other end and
across said projected stream.



19. A single pass tobacco particle classifier as in
claim 18 further including tobacco stem particle removing
means disposed in the lower portion of said chamber, and
wherein said combined stream is directed across said chamber
toward said lower portion, said arc-shaped path descending
into said removing means.



20. A single pass tobacco particle classifier as in
claim 19 wherein said means for applying upwardly moving air
streams includes a planar screen means inclined from a higher
position proximate said one end to a lower position proximate
said lower portion of said second end of said chamber.


-27-

21. A single pass tobacco particle classifier as in
claim 20 further including means for adjusting the velocity
of said combined particle stream and independent means for
adjusting the relative velocities of said air streams to
accommodate varying shapes and sizes of tobacco particles.



22. A method of separating light tobacco leaf
particles from heavier stem particles in a single pass,
vertical lift pneumatic classifier including a vertically
extending separator chamber having opposite ends, tobacco
particle feed means disposed proximate one of said ends of
the separator chamber for projecting a stream of intermixed
light leaf and heavier stem particles into and across the
separator chamber toward the other end thereof at an initial
velocity, the stream velocity decreasing as the stream
progresses across the chamber, forced air inlet supply means
for directing forced air upwardly through and across the
length of the separator chamber between said ends, light leaf
removal means in an upper portion of said separator chamber
and stem removal means in a lower portion of said separator
chamber, said method comprising the steps of:
projecting the stream of intermixed particles into
and across the separator chamber at a predetermined velocity
and angular position;
dividing the inlet forced air directed upwardly
into respective high, medium, and low velocity streams.


-28-
directing the high velocity forced air stream through the
projected stream of particles immediately after they enter
the separator chamber at said one end, and directing the
medium velocity stream through the central portion of the
separator chamber and through the medial portion of the
stream of particles, and directing the low velocity stream
adjacent the other end of the separator chamber and through
the stream of particles as they approach the other end of the
separator chamber, and
thus correlating the high-to-low velocities of the
separate air streams with the corresponding decreasing
velocities of the stream of intermixed particles being fed
across the separator chamber to gently separate the light
leaf particles from the heavier stem particles, so that the
light leaf particles rise to said light leaf removal means
and the stems fall to said stem removal means on a single
pass of the intermixed stream across said chamber.



23. A method as in claim 22 wherein the velocity
and angular position of the stream of intermixed particles is
adjustable, and including the further step of adjusting said
velocity and angular positions to further correlate the
interaction of the air streams and intermixed particle
streams.


-29-



24. A method as in claim 22 or 23 wherein the
respective velocities of the high, medium and low velocity
air streams are adjustable and including the further step of
adjusting said velocities as a function of the size and shape
of tobacco particles fed into the chamber to further
correlate the particle stream and air stream velocities to
gently separate the light leaf particles from heavier stem
particles.



25. A method according to claim 22 wherein the
pneumatic classifier includes air pattern screen means
positioned between the forced air inlet supply means and the
stream of intermixed particles being propelled across the
separator chamber, said method including the additional step
of selecting an air pattern screen having openings of a
predetermined size therein to permit a predetermined amount
of forced air to pass through the selected screen and through
the stream of intermixed particles being projected across the
separator chamber.



26. A method for separating various types of light
tobacco leaf particles from various types of heavier tobacco
stem particles in a single pass across a separating air
stream including the steps of:
combining said particles in a particle stream;
projecting said stream in an arc-shaped path;


-30-
projecting at least three independent streams of
air moving at different velocities transversely across said
path and through said projected combined particle stream with
a higher velocity air stream engaging said projected combined
particle stream at an upstream position thereof,
corresponding to a high particle stream velocity, and
successively lower velocity air streams engaging said
projected particle streams at downstream positions thereof
corresponding to successively lower particle stream
velocities; and
independently adjusting the velocity of the
particle stream and of the at least three separate air
streams to correlate all said respective velocities as a
function of the particular type of tobacco particles to be
separated.



27. A vertical lift pneumatic classifier for
separating light tobacco leaf particles from heavier tobacco
stem particles in a combined stream of particles, and being
adjustable for use with a full range of fed tobacco particle
sizes and shapes in a threshing system, said classifier
comprising:
a vertically extending separator chamber;
tobacco particle feed means located at a first end
of said separator chamber for projecting a stream of
intermixed light leaf and heavier stem particles across said
separator chamber from one end thereof toward another;


-31-
Claim 27 - cont'd ...



leaf removal means disposed proximate an upper
portion of said separator chamber;
stem removal means located at a second opposite end
of said separator chamber, opposite said tobacco particle
feed means, and at an elevation below that of the tobacco
particle feed means;
a forced air distribution surface extending across
the lower portion of said separator chamber substantially
from the chamber first end to the chamber second end, said
surface including openings permitting the introduction of
upwardly directed forced air from underneath the surface and
into the separator chamber for the purpose of lifting and
separating the tobacco leaf particles;
forced air supply means for directing forced air
upwardly through said air distribution surface and into the
separator chamber;
means associated with said forced air supply means
and said air distribution surface for establishing along the
length of said air distribution surface from said first end
of said chamber to said second end, a plurality of upwardly
directed air streams having varying velocities with the
higher velocity air streams being proximate the separator
chamber first end and the lower velocity air streams being
proximate the chamber second end, so that the velocity of the
respective upwardly directed forced air streams is correlated


-32-
with the decreasing velocity of the stream of leaf and stem
particles projected across the separator chamber; and
means for selectively adjusting the tobacco
particle feed velocity and the angular orientation of the fed
particle stream with respect to the horizontal;
the progressively changing velocities of the forced
air streams being adjustable independently of the velocity
and angular orientation of the projected particle stream in
response to the characteristics of the tobacco particles to
provide, for all tobacco particle characteristics, peeling
off of a substantial portion of the light leaf particles in
an upward direction proximate said first end and projection
of the heavier stem particles substantially along a
descending path across said chamber to said stem removal
means.
28. A vertical lift pneumatic classifier for
separating light tobacco leaf particles from heavier tobacco
stem particles in a combined stream of particles, and being
adjustable for use with a full range of tobacco particle
sizes and shapes, said classifier comprising:
a vertically extending separator chamber;
a variable speed, vaned rotor located at a first
end of said separator chamber for projecting a stream of
intermixed light leaf and heavier stem particles across said
separator chamber from said first end toward a second end
thereof;


-33-
Claim 28 - cont'd ...



a leaf removal duct disposed proximate an upper
portion of said separator chamber;
a stem removal chute located at said second end of
said separator chamber, and at an elevation below that of the
vaned rotor;
a static, planar air distribution screen extending
at a downward incline across said separator chamber
substantially from the chamber first end to a point near the
stem removal chute at the chamber second end at an elevation
below said vaned rotor, said screen surface permitting the
introduction of forced air therethrough and into the
separator chamber for the purpose of lifting and separating
the tobacco leaf particles from said stem particles, the
openings of said screen being sized to provide greater air
velocities near the chamber first end and progressively lower
air velocities as the screen extends to the chamber second
end;
forced air supply means for directing forced air
through said air distribution screen and into the separator
chamber;
air diffuser vanes associated with said forced air
supply means for establishing multiple streams of inlet
forced air, with the highest velocity stream being proximate
the chamber first end, so that the velocities of the forced
air input are correlated with the decreasing velocity of the


-34-



stream of leaf and stem particles projected across the
separator chamber;
whereby the velocity of the fed tobacco particles
and the forced air velocities along said air distribution
screen are independently adjustable in response to the
characteristics of the fed tobacco particles to provide, for
all particle characteristics, peeling off of a substantial
portion of the light leaf particles in an upward direction
proximate said first end and projection of the heavier stem
particles substantially along a descending path to said stem
removal chute.



29. A tobacco particle classifier for separating
lighter tobacco leaf particles from heavier tobacco stem
particles in a combined stream of particles and comprising:
a separator chamber having opposed ends, an upper
portion, and a lower portion;
means for projecting a combined stream of light
tobacco leaf particles and heavier tobacco stem particles in
an arc-shaped path across said chamber, from one end toward
another second end, with the velocity of said stream
decreasing as it approaches the second end;
means below said particle stream for applying to
and across said projected combined particle stream a
plurality of upwardly moving air streams having differing
velocities for gently separating lighter tobacco leaf
particles from heavier tobacco stem particles;


-35-



the higher velocity air streams engaging faster
upstream portions of the projected combined particle stream
thereacross and the lower velocity air streams engaging
slower downstream portions of the projected combined particle
stream thereacross.



30. A method of separating light tobacco leaf
particles from heavier stem particles in a combined stream of
particles in a vertical lift pneumatic classifier including a
vertically extending separator chamber having opposite ends,
tobacco particle feed means disposed proximate one of said
ends of the separator chamber for projecting a stream of
intermixed light leaf and heavier stem particles into and
across the separator chamber toward the other end thereof at
an initial velocity, the stream velocity decreasing as the
stream progresses across the chamber, forced air inlet supply
means for directing forced air upwardly through and across
the length of the separator chamber between said ends, light
leaf removal means in the upper portion of said separator
chamber and stem removal means in the lower portion of said
separator chamber, said method comprising the steps of:
projecting the stream of intermixed particles into
and across the separator chamber at a said initial velocity
and predetermined angular position;


-36-



dividing the inlet forced air directed upwardly
into respective high, medium, and low velocity streams,
directing the high velocity forced air stream through the
projected stream of particles immediately after they enter
the separator chamber at said one end, directing the medium
velocity stream through the central portion of the separator
chamber and through the medial portion of the projected
stream of particles, and directing the low velocity stream
adjacent the other end of the separator chamber and through
the projected stream of particles as they approach the other
end of the separator chamber, and
thus correlating the high-to-low velocities of the
separate air streams with the corresponding decreasing
velocities of the projected stream of intermixed particles
being fed across the separator chamber to gently separate the
light leaf particles from the heavier stem particles, so that
the light leaf particles rise to said light leaf removal
means and the stems fall to said stem removal means.



31. A method for separating various types of light
tobacco leaf particles from various types of heavier tobacco
stem particles in a combined stream of particles including
the steps of:
combining said particles in a particle stream;
projecting said stream in an arc-shaped path;


-37-

projecting at least three independent streams of
air moving at different velocities transversely across said
path and through said combined particle stream with a higher
velocity air stream engaging said projected combined particle
stream at an upstream position thereof, corresponding to a
high particle stream velocity, and successively lower
velocity airstreams engaging said particle stream at
downstream positions thereof corresponding to successively
lower particle stream velocities to separate leaf particles
from stem particles; and
independently adjusting the velocity of the
particle stream and of the at least three separate air
streams to correlate all said respective velocities as a
function of the particular type of tobacco particles to be
separated.



32. A method as in claim 31 including the further
step of depositing heavier tobacco stem particles on an
inclined screen through which said independent streams of air
pass, wherein said heavier tobacco stem particles move along
said screen toward stem removal means.



33. A particle classifier for separating lighter
particles from heavier particles in a single pass of a stream
of combined particles across a separator chamber and
comprising:


-38-



a separator chamber having opposed ends, an upper
portion, and a lower portion;
means for projecting a combined stream of lighter
particles and heavier particles in an arc-shaped path across
said chamber, from one end toward another second end, with
the velocity of said stream decreasing as it approaches the
second other end;
means for applying to said projected particle
stream a plurality of upwardly moving air streams having
differing velocities for gently separating lighter particles
from heavier particles in a single pass of said projected
particle stream across said air stream;
the higher velocity air streams engaging faster
portions of the projected combined particle stream proximate
said one end and across said projected stream and the lower
velocity air streams engaging slower downstream portions of
the projected combined particle stream proximate said second
end and across said projected stream.



34. A particle classifier for separating lighter
particles from heavier particles in a stream of combined
particles in a separator chamber and comprising:
a separator chamber having opposed ends, an upper
portion, and a lower portion;
means for projecting a combined stream of lighter
particles and heavier particles in an arc-shaped path across


-39-
Claim 34 cont'd ...



said chamber, from one end toward another second end, with
the velocity of said stream decreasing as it approaches the
second other end;
means for applying to said projected particle
stream a plurality of upwardly moving air streams having
differing velocities for gently separting lighter particles
from heavier particles in a single pass of said projected
particle stream across said air streams;
the higher velocity air streams engaging faster
portions of the projected combined particle stream proximate
said one end and across said projected stream and the lower
velocity air streams engaging slower downstream portions of
the projected particle stream proximate said second end and
across said downstream portions of said projected stream.

Description

~286632




PNEUMATIC CLASSIFIER FOR TOBACCO AND METHOD
Field of the Invention
This invention relates generally to a
pneumatic classifier for tobacco and to a method for
separating light tobacco leaf particles from heavier
stem particles, and more particularly to such a
classifier and method in which the intermixed leaf
and stem particles are fed inwardly and across a
vertical separator chamber while forced air is
directed upwardly through the intermixed particles
and at varying velocities across the length of the
separator chamber to gently separate the leaf par-
ticles from the heavier stem particles.
Background of the Invention
It is generally known to provide a pneuma-
tic classifier for separating light tobacco leafparticles from heavier stem particles. For example,
one such device is disclosed in the Rowell et al
U.S. Patent No. 3,164,548 in which the intermixed
light and heavy tobacco particles are projected into
and across the separating chamber while forced air
is directed upwardly through the particles and at a
uniform velocity across the length of the separating
chamber. The lighter leaf particles are blown
upwardly while the heavier stem particles fall down-
wardly and onto a vibrating screen positioned at aninclined angle so that the heavier particles are
discharged in a location adjacent the end of the
separator chamber containing the inlet for the
intermixed leaf and stem particles. It has been

~;

1286~3Z

found that the classifier of this patent cannot be
efficiently utilized in the earlier stages of the
separation of threshed tobacco leaves because the
leaf particles and stem particles tend to form
tanyled balls or matts, usually referred to as "bird
nests," within the separator chamber.
These bird nests are formed because the
intermixed light and heavy particles tend to attach
themselves together and the resulting bird nests are
light enough to be carried upwardly by the upwardly
moving forced air in the separating chamber so that
some heavy stem particles are carried upwardly and
removed with the lighter leaf particles. In other
lnstances, the bird nests are of sufficient weight
that they drop to the lower portion of the separator
chamber and carry some of the lighter leaf products
out the stem discharge outlet and to the next pro-
cessing stage. In any case, the formation of bird
nests is undesirable be cause they interfere with
the efficient separation of the particles in the
separator chamber, and they also tend to block or
clog the stem outlet passageway and they disburb
smooth flow of process.
U.S. Patent No. 3,608,716, issued to Lorne
A. Rowell, also discloses a similar type of pneuma-
tic classifier for tobacco including an endless
foraminous conveyor belt extending across the lower
portion of the separator chamber for removing the
heavier stem particles. This patent also discloses
a recirculating arrangement in which an air jet is
positioned in the wall opposite the~material inlet
wall to again force the particles across the chamber
and subject the particles to the upflowing air and
thereby provide a second stage of separation. This
second stage of separation is said to aid in pre-


12~6~
--3--venting the formation of bird nests. However, it
has been found that t'ne moving conveyor belt in the
separator chamber requires maintenance and periodic
replacernent at substantial cost. Also, the recir-
cuiating of the particles in the second stage ofseparation causes degradation of the lighter leaf
particles.

Summary of the Invention
With the foregoing in mind, it is an object
of the present invention to proviâe a pneumatic
classifier in which the velocity of the upwardly
flowing forced air is varied across the length of
the separator chamber and the varied velocity of the
forced air is coordinated with the velocity of the
stream of intermixed leaf and stem particles pro-
pelled into and across the separator chamber to pro-
vide a gentle separation of the leaf particles from
the stem particles and to reduce degradation of the
leaf or lamina particles.
In accordance with the present invention,
the upward flow of forced air in the separator
chamber passes through the intermingled light leaf
particles and heavier stem particles a single time
only and the heavier stem particles are discharged
on the lower portion and at the opposite end of the
separator chamber from the end on which the par-
ticles are introduced into the separator chamber so
that the heavier stem particles do not again pass
through the upwardly flowing forced air as the
heavier stem particles move to the âischarge passa-
geway. The classifier of the present invention also
eliminates the usual moving parts, such as vibrating

128663~:
--4--
screens and conveyor belts, normally positioned
inside of the separator chamber thereby minimizing
the time which is spent in cleaning and maintaining
the present classifier. The usual type of conveyor
belts are expensive to produce and replace.
The invention in one broad aspect pertains
to a particle classifier for separating lighter
particles from heavier particles in a stream of
combined particles in a separator chamber and
comprises a separator charnber having opposed ends,
an upper portion, and a lower portion, means for
projecting a combined stream of light particles and
heavier particles in an arc-shaped path across the
chamber, from one end toward another second end,
with the velocity of the stream decreasing as it
approaches the second other end, means for applying
to the projected particle stream a plurality of
upwardly moving air streams having differing
velocities for gently separating lighter particles
from heavier particles in single pass of the
projected particle stream across the air streams,
the higher velocity air streams engaging faster
portions of the projected combined particle stream
proximate the one end and across the projected
stream and the lower velocity air streams engaging
slower downstream portions of the projected
particle stream proximate the second end and across
the downstream portions of the projected stream.
Another broad aspect comprehends a method
for separating various types of light tobacco leaf
particles from various types of heavier tobacco
stem particles including the steps of combining the
particles in a particle stream, projecting said
stream in an arc-shaped path, projecting at least
three independent streams of air moving at
different velocities transversely across the path
and through the projected combined particle stream
with a higher velocity air stream engaging the

- 1~86632
projcctcd comt)irled pa~ticle~ stream al an ups-tream
pos-ition thereof, correspollding to a high particle
strearn velocity, and successive]y lower velocity
air strearns engaging the projected particle streams
at downstream positions thereof corresponding to
succeC;sive]y lower partic:Le stream velocities
~o separate- ~ lf~ lrticles ~rorn sterrl pdr~icles, and
independent~y adjllstir~g the velocity of the
particle stream and of the at least three separate
air streams to correlate all the respective
velocities as a function of the particular type of
-tobacco particles to be separated.
More particularly, the pneuma-tic
classifier of the invention includes a vertically
extending separator chamber with a material inlet
feed on one side of the separator chamber for
feeding a stream of intermixed light tobacco leaf
particles and heavier stem particles into and
across the separator chamber at a predetermined
initial velocity and with the velocity of the
stream of intermixed leaf and stem particles
decreasing as they travel from the inlet feed and
toward the opposite end of the separator chamber. A
forced air inlet is provided in the lower end of the
separator cnamber for directing a stream of forced
air into the lower inlet or the separator chamber at
a predetermined velocity.
Air distribution means is provided between
the forced air inlet and the stream or leaf and stem
particles for separating the inlet air stream into
at least 'nigh, medium and low velocity streams and
for also directing the separated air streams in an
upward flow through the separator chamber with the
high velocity air stream moving upwardly adjacent
tlle end of the separator chamber into which the par-
ticles are introduced so that the high velocity
upwardly flowing air passes through the intermingled
leaf and stem particles immediately after entering
the separator chamber and w~ile traveling at their
greatest velocity. The medium velocity air stream
moves upwardly in the central portion of the separa-
tor chamber and passes through the medial portion or

~2~6632
--5--
the stream of leaf and stem particles while they are
traveliny at an intermediate velocity and after a
considerable number of the leaf particles have been
intially separated from the stream. The low velo-
city air stream moves upwardly adjacent the otherend of the separator chamber and passes through the
stem and any remaining leaf particles as they
approach the other end of the separation chamber.
The stem removal outlet is positioned in the lower
portion of the other end of the separator chamber so
that the heavier stem particles are directly pro-
jected into the stem or "heavies" outlet.
The air distribution means includes
adjustable means in the form of air transfer deflec-
tor plates or baffles and air diffuser guidesextending from a position upstream of the air inlet
and into the lower portion of the separation
chamber. The adjustable deflector baffles and the
diffuser guides operate to divert and spread the
inlet forced air into the three air streams of
varying velocity across the width of the separator
chamber.
The air distribution means also includes
sets o~ plenum screens extending across the lower
portion of the separator chamber and above the dif-
fuser guides. Each set of the plenum screens is
provided with openings of different sizes to aid in
controlling the velocity and distribution of the
upwardly flowing forced air stream, in accordance
with the type of tobacco particles being fed into
the separation chamber. A set of pIenum screens
with different size openings can be easily inserted
into the separator chamber to adapt the classifier
for any particular position in the various stages of

128663Z

separat iOIl in a plant where a large number of
classifiers may be operating in a complete threshiny
line. The plenum screen i3 supported at an inclined
angle toward the stem outlet for directing any stem
particles or fines deposited thereon toward the stem
outlet. The upwardly flowing forced air passing
through the plenum screen has a tendency to lift
the stem particles and fines and thereby aids in the
same along the surface of the plenum screen and into
the stem outlet.
An adjustable deflector plate is positioned
at the inlet for the intermixed or intermingled leaf
and stem particles and is operable to adjust the
angle of trajectory of the particles entering and
being propelled across the separator chamber. This
adjustable deflector ylate also aids in obtaining
the most efficient separation of the leaf and stem
particles as they travel from the inlet feed and
toward the opposite end of the separator chamber.
Brief Description of the Drawings
Other objects and advantages will appear as
the description proceeds when taken in connection
with the accompanying drawings, in which --
Figure 1 is an isometric view of one side
of the classifier of the present invention;
Figure 2 is an enlarged isometric view of a
separator screen of the type utilized in the separa-
tion chamber, being removed from the classifier;
Figure 3 is a fragmentary side elevational
view of the central portion of Figure l;
Figure 4 is an enlarged vertical sectional
view through the separator chamber of the classi-
fier; and

1286~i32

Figure 5 is a side elevational view of the
opposite side of the classifier from that shown in
Figure 1.
Description of the [llustrated Embodiment
The pneumatic classifier illustrated in the
drawings may be successfully operated in any one of
the stages of separating the lighter leaf particles
from the heavier stem particles throughout the
entire threshing line of classifiers. The velocity
of the separating air throughout the length of the
separator chamber is varied and coordinated with the
velocity of the stream of intermixed leaf and stem
particles as they are propelled across the separator
chamber to thereby provide a gentle separation of
the lighter leaf particles from the heavier stem
particles. The present classifier may be termed a
"single pass" system because lighter leaf particles
and the heavier stem particles are engaged by the
upwardly flowing forced air only one time in the
separator chamber.
As illustrated in the drawings, the present
pneumatic classifier includes a vertically extending
separator chamber defined by a main housing, broadly
indicated at 10, and including substantially ver-
tical opposite side walls 12, 13 connected togetherby respective inlet and outlet walls 14, 15 with
their upper ends converging toward each other, as
best shown in Figure 4. Material inlet feed means
communicates with the inlet side wall 14 and includ-
es a substantially vertically extending inlet chute18 for receiving the intermixed or ~ntermingled leaf
and stem particles from any suitable type of con-
veyor, not shown. The inlet chute 18 directs the
intermixed particles downwardly into an inlet rotor

12t~6632

housing l9 in which a vaned rotor 20 is supported
Lor rotation in a cylindrical portion thereof. One
end of the drive shaft of the rotor 20 is provided
with a drive pulley 21 (E'igure 5) engaged by a drive
belt 22 which is in turn drivingly engaged by an
output drive pulley 23 of a variable speed electric
motor 24 for imparting counterclockwise rotation to
the rotor 20, as illustrated in Figure 4.
An adjustable deflectGr plate 25 is sup-
ported adjacent the discharge position of the rotor
20 for varying the path of movement of the particles
projected across the separator chamber, as indicated
by the arrows in Figure 4. In order to raise or
lower the inner portion of the deflector plate 25 to
the desired adjusted position, the outer end portion
of the deflector plate 25 is fixed on a control
shaft which extends outwardly through the rotor
housing 19 and is fixed to the inner end portion of
an angularly disposed control lever 30 (Figure 3).
A threaded bushing is connected to the outer end of
the control lever 30 and is threadably penetrated by
an elongate adjustment screw 31 which is supported
in a vertical position at its upper and lower ends.
A rotating hand wheel 32 is fixed to the lower end
of the adjustment screw 31 for rotating the same.
By selectively rotating the hand wheel 32, the ad-
justment screw 31 either raises or lowers the outer
end of the control lever 30 correspondingly lowers
or raises the inner end of the deflector plate 25.
The rotor 20 initially feeds the stream of
intermingled leaf and stem particles into the inlet
side of the separator chamber at a predetermined
velocity, which is determined by the speed of the
variable speed motor 24 and the speed of rotation of
the rotor 20. The input velocity of the stream ot

lZ136632

g
intermingled leaf and stem particles decreases as
the particles travel from the inlet feed side and
toward the opposite end waLl 15 of the separator
chamber. The deflector plate 25 serves two primary
functions and it is adjusted, according to the
characteristics of the tobacco particles being fed
by the rotor 20, to vary the angle at which the par-
ticles are projected across the separation chamber
so as to change the cross-sectional area of the
classifying plane by either passing the particles
along a higher or lower velocity stream without
necessarily having to make any adjustment of the
velocity of the upwardly flowing forced air. Also,
the deflector plate can be adjusted to direct the
stem particles more directly into the discharge
chute, to be presentl-y described, and to thereby aid
in preventing a choke-up of the discharge chute.
Forced air inlet supply means is provided
in the lower end of the separator chamber for
directing a stream of forced air into the lower end
of the inlet end of the separator chamber at a pre-
determined velocity. The forced air inlet supply
means includes a substantially cylindrical housing
35 (Figure 5) in which a fan blower 36 is supported
for rotation. A drive shaft 37 of the fan blower 36
extends outwardly through one side of the housing 35
and is rotatably supported on bearing blocks 40
fixed on a motor support stand 41 (Figure 1). An
electric drive motor 42 is fixed on the stand 41 and
3~ is drivingly connected to the drive shaft 37 by
means of drive pulleys and a drive-~elt 43. An air
duct 45 connects the cylindrical housiny 35 with the
inlet end of the separator chamber 10 and includes
an upwardly turned air bleed-off duct 46.

lZ866~;~
-10-
As illustrated in Figure 4, a forced air
inLet, broadly indicated at 50, is provided in the
lower left-hand portion of the separator chamber 10
and includes air distribution control means posi-
tioned between the forced air inlet 50 and thestream of leaf and stem particles being directed
across the separator chamber by the rotor 20. The
air distribution includes air diLfuser guides 94
which help spread the air volume across the separa-
tor chamber and comprise in the present preferredembodiment four rotatably mounted rods perpendicular
to and in the airstream and mounting a plurality
of circular air diffuser plates (best illustr~ted in
Figure 1). T'ne air distribution means also includes
a pair of air transfer deflectors 51 including ver-
tically adjustable leading or upstream ends, as
indicated by the arrows in Figure 4. The deflectors
51 divide the incoming forced air into three
separate air streams, the velocity of each of which
may be varied according to the positions of the air
transfer deflectors 51. The trailing or downstream
ends of the air transfer control means or deflectors
51 are fixed on control shafts which extend out-
wardly through the housing (Figure 3) and are fixed
to the ends of corresponding control levers 53'.
The other ends of the control levers 53' may be
raised and lowered to thereby change the angle of
the deflectors 51. The deflectors 51 are maintained
in the adjusted position by suitable locking means,
illustrated in Figure 3 in the form of lock bolts
extending through slotted brackets-~ixed on the side
wall 12.
The air distribution means also includes
means for directing the separated air streams
upwardly and along different upwardly flowing paths

lZ~3~

--11--
of travel across the width of the separator chamber
lU. The air directing means includes air transfer
control means in the form of a pair of fixed air
diffuser yuides 52 which have their upstream ends
fixed in alignlDent with trailing the ends of the air
transfer deflectors 51 and their downstream ends are
fixed in positions spaced across the path of move-
ment of the forced air into the lower section of the
separator chamber 10. Adjustable air transfer
control means in the form of air diffuser vanes 53
have their upstream ends supported for adjustment
across the width of the corresponding air passage
ways provided by the fixed air diffuser guides 52,
as indicated by the arrows in Figure 4. The
downstream ends of the adjustable air diffuser vanes
53 are fixed in substantially equidistant rela-
tionship between and substantially dividing the
separate air velocity chambers formed by the side
walls and the fixed air diffuser guides 52.
An air pattern screen, broadly indicated at
60, (Figure 2) extends across the lower portion of
the separator chamber 10 (Figure 4) at an angle of
approximately 30 and substantially perpendicular to
the flow of the separate streams of forced air
entering the lower end of the separator chamber 10.
The air pattern screen 60 is positioned immediately
adjacent the downstream ends of the fixed diffuser
guides 52 and the adjustable air diffuser vanes 53.
The screen 60 (Figure 2) is provided with a frame 61
supporting a screen section 62 and a solid section
64. A slot is provided in the side~`wall 12 so that
the air pattern screen 60 may be easily removed and
inserted therein. One side edge of the frame 61 is
provided with a closure plate 65 having handles 66
and the screen 60 is maintained in position by stop

~28~i6~2
-12-
closures engaging the closure plate 65. A set of
the screens 60 is provided with each classifier and
t~le size ot the mesh or openings of each screen of
the set is varied. Also, mesh size can be varied
across each plenum screen in the set to vary the air
flow across the length of t:he separator chamber 10.
Thus, a screen with the proper size mesh or openings
can be inserted in the separator chamber 10 to con-
trol the distribution of air flowing therethrough,
for purposes to be presently described.
As shown in Figure 4, stem removal means,
broadly indicated at 69, is provided in the lower
portion and on the opposite end of the separator
chamber 10 from the inlet feed rotor 20. The stem
removal means 69 includes a discharge outlet housing
70 communicating with the outlet in the lower left-
hand portion of the separator chamber 10 and posi-
tioned immediately adjacent the lower end of the air
pattern screen 60 (Figuré 4). An optional outlet
rotor (not shown) may be supported for rotation in
the housing 70. A stem discharge conveyor belt 80
is positioned beneath the lower end of the stem
outlet and i3 driven by a suitable motor, not shown,
to remove the separated stem particles to a suitable
location away from the classifier.
A leaf particle removal duct 82 i3 provided
on the upper end of the separator chamber 10 and has
inwardly tapered forward and rear walls, and a rear-
wardly curving and horizontal portion connected to
the forward end of a rectangular leaf particle
transport duct 85. The rear end of'''the duct 85 is
connected to the inlet of a tangential separator
housing 90 which forms part of a centrifugal type
discharge unit.

12~6632
-13-
If desired, the central portion of the
tanyential separator housing 90 may be provided with
a cylindrical screen, not silown, to prevent the dis-
charge of any light leaf products through the outlet
or the fan blower and into a cylindrical return air
duct 96. The cylindrical return air duct 96 is con-
nected to the inlet side of the air inlet fan blower
housing 35, as illustrated in Figure 1 so that the
air utilized in the separation operation is
recycled. The air volume is controlled by an
adjustable damper, shown generally at 93.
In order to be able to easily observe the
operation in the separation chamber, it is preferred
that the opposite side walls 12, 13 and the outlet
wall 15 of the separation chamber be provided with
windows, as illustrated at 97 in Figures 1, 3 and 5.
It is also prererred that a suitable fluorescent
light support chamber 98 be provided in the removal
duct 82 to illuminate the upper portion of the
separator chamber 10 so that the separation opera-
tion can be easily viewed through the windows 97 and
proper adjustments can be made in the air velocity
and/or the input rotor 20.
As the light leaf particles are separated
from the return air in the tangential separator
housing 90, they fall downwardly into a leaf output
air-lock 100 (Figure 5) supported for rotation in
the lower portion of the tangential separator
housing 90. The output rotor 100 is provided with a
drive shaft which extends outwardly beyond the side
of t'he housing 90 (Figure 1) and is''provided with a
drive pulley 102. A drive belt 103 drivingly con-
nects the drive pulley 102 and to the drive pulley
of a variable speed drive motor 104. Any suitable
type of conveying mechanism or removal sys-tem may be

128663Z
-14-
employed to transport the separated ligllt Leaf par-
ticles from the output rotor 100 of the classifier.
Figures 1 and 5 illustrate a tubular collection
device 106 which may be suitably connected to a
pneumatic conveying duct for removing the separated
li~ht leaf partlcles.
Method of Operation
The incoming intermingled light leaf and
heavier stem particles are engaged by the rotor 20
and a stream of the intermixed particles is pro-
pelled into and across the separator chamber 10, as
illustrated by the arrows in Figure 4, and at a pre-
determined velocity. The initial velocity of the
particles, as they enter the separator chamber, may
be varied by adjustiny the speed of the variable
speed motor 24. ~le initial velocity of the par-
ticles entering the separator chamber 10 is varied
in accordance with the type of particles being fed
into the separator chamber, this usual velocity is
within the range of about 1,000 to 1,200 feet per
minute. The velocity of the stream of intermingled
leaf and stem particles gradually decreases as the
particles travel from the inlet feed to the opposite
end of the separator chamber 10.
The angular position of the deflector plate
25 is adjusted to obtain the desired cross-sectional
area of the classifying plane. The deflector plate
25 may be adjusted so that the heavier stem par-
ticles are projected in a smooth, substantially
horizontal curving arc almost directly into the
discharge chute 70. The deflector plate 25 may be
adjusted so that the heavier stem particles are pro-
jected against the substantially smoothly curved
surEace of the outlet wall 15 so that they fall
downwardly into the discharge chute 70. As the

~Z866~2

iotermixed particles pass along the classifying
pLane and across the separator chamber 10, they are
engaged by the upwardly flowing forced air currents,
as indicated by the arrows in Figure 4, so that the
lighter leaf particles are gently separated from the
heavier stem particles and carried upwardly through
the removal duct 82 and into the tangential separa-
tor housing 90.
The air distribution means at the forced
air inlet 50 of the separator chamber 10 is adjusted
to provide the most efficient separation of the
light leaf particles from the heavy stem particles
in the separation chamber. The incoming forced air
is controlled to provide air streams of varying
velocities across the length of the separator
chamber 10 and the velocities of the separating air
are coordinated with and adjusted in proportion to
the decreasing velocity of the particles as they
move across the length of the chamber 10 so that the
lighter leaf portions are "peeled" off from the stem
particles and moved in an upward direction almost
immediately after entering the separator chamber
10 .
The air transfer deflectors 51 and the air
diffuser guides 52 are adjusted to provide a higher
velocity air stream on the rotor or input side of
the separator chamber 10. The air stream entering
between the transfer deflectors 51 and directed by
the air diffuser guides 52 and 53 into the medial or
central portion of the separator chamber 10 travels
at a medium velocity, somewhat less'''than the velo-
city of the upwardly flowing air stream adjacent the
inlet rotor 20. The air stream entering below the
lower transfer deflector 51 and directed into the
discharge side of the separator chamber 10 by the

lZ8(j632
-16-
diffuser yuides 52, 53 is partially blocked by the
solid portion 64 of the screen 60 and travels
upwardly along tlle outlet side of the separator
chamber 10 at a lower velocity than the other two
air streams. The velocity of each of the air
streams is correlated with the decreasing velocity
of the particles passing across the separator
chamber 10 to obtain the most efficient separation.
~le velocity of the upwardly flowing air
streams in the separator chamber 10 is usually on
the order of from about 600 to 800 feet per minute,
depending upon the type of tobacco product which is
being separated. As a specific but nonlimiting
example, it has been found that efficient separation
takes place when the air stream entering above the
deflector 51 and directed into the area immediately
adjacent the input impeller 20 is controlled at a
velocity of about 800 feet per minute. The air
stream entering between the two transfer deflectors
51 and guided into the central portion of the air
separator chamber 10 is controlled at a velocity of
about 450 feet per minute. The air stream entering
below the lower deflector 51 and being directed into
the outlet side of the air chamber 10 is controlled
at a velocity of about 200 feet per minute.
Air pattern screen 60 can be used to change
the distribution of air flowing through the stream
of particles. A screen 60 with large openings can
be inserted to increase the volume of air, and a
screen 60 with smaller openings can be inserted to
decrease the volume of air. Thus, flow charac-
teristics of the forced air wi-thin the separator
chamber 10 can be varied by simply changing the type
of air pattern screen 60 being utilized. These air
pattern screens 60 can be exchanged in a few seconds

~286632

so that the present classifier can be effectively
used in any stage of an ent:ire threshing line.
In the present classifier, there are no
moving parts in the air separator chamber and the
separating air passes through the incoming stream of
tobacco particles at a velocity which is in substan-
tial proportion to and correlated with the velocity
of the particles passing across the separator
cnamber. This control of the separating air provi-
des a gentle and smooth separation of the light leafparticles from the heavy stem particles and ensures
that the separation takes place without degrading
the leaf particles. To reduce the exhausting of
fines and other small particles into tihe atmosphere
surrounding the classifier, it is preferred that a
slight negative pressure be maintained in the
pneumatic circuit of the classifier.
In the drawings and specification there has
been set forth the best mode presently contemplated
for the practice of the present invention, and
although specific terms are employed, they are used
ln a generic and descriptive sense only and not for
purposes of limitation, the scope of the invention
being derined in the claims.

Representative Drawing