Note: Descriptions are shown in the official language in which they were submitted.
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Title: MATERIAL CLASSIFIER
Field of the Invention
[001 ] The present invention relates to material classification systems and in
particular
relates to material classifier using a cyclone.
Background of the Invention
[002) In order to transport granular materials they are often entrained in air
or some
gas. By fluidizing granular material in air, one is capable of transporting
the granular
materials through pipes, long distances to desired locations. Once the
material has reached
its desired location, the material being transported must be separated from
the air which is
usually accomplished with a cyclone. Therefore in most material conveying
systems using
air fluidization or entraining granular particles within air, the final air
material separation is
often accomplished with a cyclone.
[003] Furthermore, there is often the requirement that the granular materials
being
transported, further needs to be classified into different sizes. The most
fimdamental
classification that usually is required is separation of coarser material from
finer material for
subsequent operations. There are a number of existing devices which
independently of the
cyclone have the capability of classifying materials into different sizes. It
would be
desirable, however to use the cyclone in addition to its air separating
ability to also be able
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to classify the materials into different sizes. This would eliminate an
intermediate step and
the equipment associated with classifying granular materials into various
sizes.
j004] There have been attempts at accomplishing this within the cyclone, in
for
example prior art in International Application WO 03/03315 8 A 1, titled Dust
Separator, filed
by Rapid Granulator AB on October 19, 2001, wherein they describe a cyclone
which is used
for the separation of dust from granular material, using a separator chamber
mounted on the
lower side of a cyclone. Particles dropping out of the bottom of the cyclone
pass into a
separator chamber and impinge upon a deflector device, wherein via this impact
any dust
upon the particles settling out of the bottom of the cyclone is dislodged and
carried upward
through a "inner wall" of the cyclone. Further, the art teaches plates
disposed within the
inner walls, whose purpose is to prevent or reduce rotation ofthe flow which
takes place with
the major direction upwards within the "inner wall" of the cyclone. An air
inlet is located
below the separator chamber. A downwardly angled portion of the inlet conduit,
introduces
air and is controlled by a regulator valve. The art taught in this patent is
directed towards
removal of dust which is adhered to larger granular particles. The apparatus
intends to
dislodge the dust from the larger granular materials by impinging the larger
granular
materials upon the deflector devices within a separation chamber. This unit is
limited to the
collection and removal of extremely fine dust particles from granular
materials.
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[005] There is however, a need to be able to use a cyclone as a material
classifier to
be able to classify granular materials into coarse and fine in addition to
having the capability
of dust removal as indicated in the prior art PCT Application WO 03/033158 A1.
Summary of the Invention
[006] The present invention a material classifier includes:
a) a cyclone including a cyclone inlet, a cyclone outlet, a blower and a
blower
discharge;
b) an air diffuser connected at a diffuser inlet to said cyclone outlet and at
a diffuser
outlet to an air lock such that said cyclone and air diffuser are in fluid
communication;
c) wherein said diffuser including a central cylindrical portion including an
air inlet
means for admitting controlled amounts of diffuser air around substantially
the entire
cylinder outer periphery of said central cylindrical portion, wherein said
material
classifier separating fine particles from coarse particles and discharging
said fine
particles together with air out said blower discharge, and discharging said
Gorse
particles through said air lock, such that increasing the amount of diffuser
air
increases the size of the fine particles being separated from the coarse
particles.
[007] Preferably wherein said diffuser air is admitted into said cyclone in
such a
manner as to enhance and reinforce the formation of a strong interior vortex.
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[008] Preferably wherein said air inlet means including numerous air inlet
apertures
spaced around said cylinder outer periphery for admitting diffuser air
[009] Preferably wherein said air inlet means including numerous air slots
spaced
S around said cylinder outer periphery for admitting diffuser air.
[0010] Preferably wherein said air slots extending along a longitudinal axis,
and said
slots oriented at an angle theta measured between said longitudinal axis and
vertical such that
when diffuser air is admitted through said angled slots said air flow
supporting development
of an interior cyclone in said cyclone.
[0011 ] Preferably wherein said angle theta between 10 and 80 degrees.
[0012] Preferably wherein said slots are so oriented so as to enhance and
reinforce a
formation of a strong interior vortex.
[0013] Preferably wherein said air inlet means further including a control
means for
adjustably controlling the amount of diffuser air being admitted through said
air inlet means
and into said air diffuser.
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[0014] Preferably wherein said control means including an annular adjustable
band
extending and clamping around the cylinder outer periphery for selectively
covering off ali
or some of the slot area.
[0015] Preferably wherein said control means including a barometric damper for
adjusting the amount of diffuser air depending upon the material through put
of the cyclone.
[0016] Preferably wherein said central cylindrical portion being larger in
diameter than
a cyclone outlet diameter.
[0017) Preferably wherein said central cylindrical portion having a diameter
at least
1.2 times that of the cyclone outlet diameter.
[0018] Preferably wherein said cyclone being a mid efficiency cyclone having a
air
1 S inlet velocity of no more than 3000 feet per minute.
[0019) Preferably wherein said cyclone dimensioned and adapted to promote
formation of an exterior downwardly spiralling vortex and an up draft interior
upwardly
spiralling vortex.
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[0020] Preferably wherein said cyclone further including a stand pipe
dimensioned to
aid and enhance the development of a strong updraft interior vortex.
[0021 ] Preferably wherein said air diffuser including an upper tapered
portion for the
transition between the diffuser inlet and the central cylindrical portion.
[0022] Preferably wherein said central cylindrical portion being a hollow body
and a
vertical length greater than the diameter of the cyclone outlet.
[0023] Preferably wherein the entrained particles being selected from the list
including
granulate, pellets, fibres, flakes, beans, plastic, metal, and paper.
Brief Description of the Drawings
[0024] The invention will now be described by way of example with reference to
the
following drawings in which:
Figure 1 is an upright schematic perspective view of the present invention a
material
classifier.
Figure 2 is an upright schematic partial cut-away perspective view of the
present
invention a material classifier.
Figure 3 is a schematic perspective view of a regrind system including the
present
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invention a material classifier.
Figure 4 is a schematic perspective partial cut away view of a regrind system
showing
the present invention the material classifier.
Figure 5 is an upright schematic perspective view of the air diffuser portion
part of
the material classifier.
Figure 6 is a side plan elevational view of an alternate embodiment of the
body
portion of a material classifier shown in Figure 6, 8 and 9.
Figure 7 is a upright schematic perspective view of an alternate embodiment of
a
material classifier showing various inlet heights.
Figure 8 is an upright schematic perspective view ofthe alternate embodiment
ofthe
material classifier shown in Figure 7, showing by way of example two different
inlet
angles, alpha and two different bottom outlet diameters.
Figure 9 is an upright schematic transparent view of an alternate embodiment
of the
material classifier with a conical top showing the interior vortex and the
exterior
vortex.
Detailed Description of the Preferred Embodiment
[0025] The present invention a material classifier shown generally as 20 is
shown in
figure 4 deployed together with other equipment making up a regrind system
shown generally
as 22. Regrind system 22 takes plastic components and/or plastic parts or
rejected plastic
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parts and feeds them through a grinder shown generally as 501 which produces
granular
material containing both coarser particles, finer particles and of coarse also
some dust. All
of this granular material is conveyed to material classifier 20, wherein the
coarse granular
particles 106 are separated from the finer granular particles 107 as well as
dust which may
be entrained, such that coarse particles 106 are discharged from air lock
housing 401 and
finer granular materials as well as dust together with air is discharged from
blower discharge
250 to bag house 502.
[0026] The present invention, material classifier shown generally as 20 as
shown in
figures 1 and 2 and includes the following major components namely cyclone
100, blower
200, air diffuser 300 and air lock 400. Cyclone 100 includes cyclone housing
101, tangential
cyclone inlet 102, cyclone outlet 103, internal stand pipe 104 and blower air
105 shown
generally as dark arrows. Note that blower air 105 shown as dark arrows will
have entrained
therein depending upon the location within the process, coarse particles 106,
fine particles
107, diffuser air 304 as well as dust. Note that diffuser air flow is
generally shown as light
or white arrows 108 and diffuser air flow 108 will have entrained in it,
depending upon the
location within the device, fine particles 107 as well as dust. Cyclone 100 is
the type known
in the art and normally utilized for separating air from particles entrained
or fluidized in the
air.
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[0027] Blower 200 includes the following major components, blower housing 201
having mounted therein a fan 202 driven by a motor 203, having a blower
discharge 250,
wherein blower 200 draws in blower air 105 through cyclone inlet 102 and
further through
stand pipe 104 and out through blower discharge 250.
(0028] Air diffuser 300 includes a substantially hollow cylindrically shaped
diffuser
housing 301, diffuser inlet 302, diffuser outlet 303, diffuser air 304, shown
generally as light
or white arrows 108. Diffuser air 108 is introduced into air diffuser 300 via
air slots 305
which can be opened and closed with adjustable band 302 having an adjusting
bolt 310, such
that adjustable band 306 can be moved along vertical direction 330. Figure 5
shows
adjustable band 306 in the fully opened position 320 in solid lines and the
partially closed
position 322 in dashed lines. Diffuser housing 301 includes an upper tapered
portion 312,
a central cylindrical portion 314, a lower tapered portion 314, wherein
diffuser inlet 302 has
a inlet diameter 340 which is the same as the cyclone outlet diameter and
wherein central
cylindrical portion 314 has a cylindrical diameter 342.
[0029] Material classifier 20 further includes some type of air lock 400 shown
in these
diagrams buy way of example only as a rotary air lock 400, including an air
lock housing
401, an air lock inlet 402, a discharge 402 and a rotor 404. Kindly note that
air lock 400 can
be any of the types known in the art, not necessarily a rotary air lock as
depicted here as long
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as the air lock 400 is able to separate solid materials from air.
[0030] The regrind system shown generally as 22 in figures 3 and 4, includes a
grinder
501 having a grinder housing 503, and a raw material inlet 502 further
including piping 511
for transportation of granular material to the material classifier 20. Prior
to the fluidized
material entering cyclone 100, it is preferably passed through an anti-static
system 110,
wherein charged particles 172 enter into anti-static system 110 are
neutralized such that
uncharged coarse particles 106 leave anti-static system 110. Anti-static
system 110 will
neutralize both coarse and fine particles as well as dust particles, even
though this is not
depicted in the drawings. Material classifier 20 separates coarse particles
which exit through
the bottom of discharge 403 of air lock 400, wherein fine particles 107 exit
at blower
discharge 250 via piping 511 to a bag house 502 which includes a plenum 505,
air filters 506
and fine containers 507.
In Use
[0031 J Granular material is received into cyclone 100 through cyclone inlet
102 which
is positioned in such a manner to set up cyclonic motion within cyclone
housing 101 as
depicted schematically with the dark black arrows which are denoted as blower
air 105.
Blower 200 having fan 202 driven by fan motor 203, creates a vacuum or suction
on cyclone
inlet end 102 and draws granular material in through cyclone inlet 102.
Granular material
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normally includes coarse particles 106, fine particles 107, and dust particles
not shown as
well as blower air 105 all mixed together at cyclone inlet 102. Cyclone inlet
102 is normally
positioned above a vertical stand pipe 104 centrally and coaxially mounted
within cyclone
housing 101. This cyclone geometry well known in the art creates a circular
flow around the
exterior portion of cyclone housing 101 as depicted by the dark arrows of
blower air 105 and
the heavier coarse particles 106 through centrifugal force are swept to the
exterior periphery
of cyclone housing 101 and make their way downwardly in vertical direction 191
towards
cyclone outlet 103. Blower air 105 drawn into fan 202 of blower 200 enters
stand pipe 104
and up and through fan 202 and out blower discharge 250.
[0032] It is believed that an up draft and or a counter rotating vortex is
created
vertically below stand pipe 104 which typically provides for the removal of
blower air 105
through blower 200 and out through blower discharge 250.
[0033] Therefore there is an exterior spirally downwardly rotating vortex 701
with
heavier coarser particles 106 entrained therein and moving vertically
downwardly along
vertical direction 191 and there is an interior updraft or spirally upwardly
counter rotating
vortex 702 developed proximate the central portion of cyclone housing 101 and
in this
manner blower air 105 is removed from cyclone housing 101 at times together
with dust out
of blower discharge 250.
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[0034] Prior art International Application WO 03/033158 A1 adds an additional
separator chamber 18 below cyclone 100 which has mounted therein a deflector
device 19,
wherein coarser particles impinge upon the deflector device, such that
additional dust is
dislodged from coarser particles and by additionally allowing air to enter
below a separator
chamber, this dust is then carried out with the air discharge rather than
through the air lock.
[003 5] In the present invention as coarse particles 106, together with fine
particles 107
as well as dust, makes its way downwardly in cyclone 100 towards cyclone
outlet 103 and
into air diffuser 300, particles of all sizes meet with diffuser air 304 which
is allowed to
enter through air slots 305 which are defined around the entire cylinder outer
periphery 350
of central cylindrical portion 314 of diffuser housing 301.
[0036] Diffuser air 304 entering through air slots 305 defined around the
entire
cylinder out periphery 350, fluidizes or entrains, fine particles by
supporting and enlarging
the up draft interior vortex 702 and effectively strengthens the upward force
of interior
vortex 702 and diffuser air 304 rising upwardly into stand pipe 104 creates a
strong upward
draft such that by controlling the amount of diffuser air 304, one controls
the strength and
velocity of air within interior vortex 702 and in this manner, one can control
the size of
particles which are fluidized by interior vortex 702 and which eventually make
their way
through blower 200 and out through blower discharge 250.
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[0037] Experimentally, it has been found that it is important to support the
existing up
draft interior vortex 702 as well as the exterior vortex 701 through the
design of the inlet of
diffuser air 304 into cyclone 100.
[0038] Unlike the prior art as described in WO 03/033158 A1 which in fact
indicates
that they are using plates within a the stand pipe for the purpose of
preventing or reducing
rotation of flow which takes place with the major direction upwards inside the
inner walls.
The present invention utilizes the existing upwards flow within cyclone by
controllably
strengthening and enhancing the up draft flow within the interior vortex 702
in order to
selectively fluidize particles of pre determined size.
[0039] As a result, it has been found that by angling air slots 305 at an
angle theta 344
measured between a longitudinal axis 345 and the vertical direction 191, one
is able to
enhance and encourage the up draft interior vortex 702 by placing the air
slots 305 around
cylinder outer periphery 350 in an angled relationship having an angle theta
344 as shown
in figure 5. Adjustable band 306 having an adjustment bolt 310 is strapped
around central
cylindrical portion 314 of air diffuser 300 and can be adjusted by loosening
off bolt 310 to
a fully opened position as shown in 320 in figure 5 or a partially closed
position 322 as
shown as dashed lines in figure 5 or in fact it can fully close off air slots
305 by placing
adjustable band 306 entirely covering air slots 305.
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[0040] Through trial and error and experimentation it has been found that it
is
important that central cylindrical portion 314 have a cylinder diameter 342
larger than inlet
diameter 340 which is basically the same diameter as cyclone outlet 103. It
has been found
that in order to enhance and aid the interior vortex 702 development, one
needs to introduce
diffuser air 304 at a cylinder diameter 342 which is larger than the cyclone
outlet diameter
103. In addition, it has been found very important that air be introduced
around the entire
periphery of cylinder outlet 350, rather than at just a single point, once
again in order to aid
the development and strength of interior vortex 702 which is rotating counter
clock wise and
rising upwardly within cyclone housing 101.
[0041 ] In practice one has been able to control the classifier such that the
material size
exiting out of blower discharge 250 can be carefully controlled by allowing
more or less
diffuser air 304 through air slots 305 of air diffuser 300. The heaviest
particles will
immediately tend to the outer diameter of cyclone housing 101 and will drop
through air
diffuser 300 undisturbed and into air lock 400.
[0042] However by introducing more diffuser air 304 through air slots 305, the
interior
vortex 702 becomes stronger and more fully developed and will fluidize and
carry upwardly
larger and larger granules of particles up through stand pipe 104 and out
through blower
discharge 250, such that one can select the size of particles into at least
two distinct sizes,
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namely coarser particles 106 and fine particles 107, in addition to dust
removal.
[0043 ] A person skilled in the art will note that cyclone 100 in any event
removes dust
particles not shown in the attached diagrams and the prior art in
International Application
WO 03/033158 A1 has indicated a method or a means of adding or enhancing dust
removal
through a conventional cyclone 100.
[0044] In addition to dust removal, material classifier 20 has the capability
of
selectively removing heavier particles and in fact can classify incoming
particles into at
least two classifications namely coarse particles 106 which are discharged
from discharge
402 of air lock 400 and fine particles 107 which are discharged from blower
discharge 250.
The fine particle size can be controllably selected by adjusting the amount of
diffuser air 304.
[0045] Material classifier 20 appears to be most effective when using a mid-
efficiency
cyclone 100 rather than a high efficiency cyclone. A mid efficiency cyclone
generally has an
air velocity of less than 3000 feet/min.. High efficiency cyclones tend to be
smaller in
diameter and longer in length and have a strong exterior vortex 701 and it is
the inventors
theory that the interior vortex 702 tends to be extremely weak and therefore
it is difficult to
support and/or enhance the interior vortex 702 development with the addition
of diffuser air
304 through air slots 305. In any event, through trial and error and
experimentation, it has
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been found that a larger diameter cyclone 100 known in the industry as a mid
efficiency
cyclone, appears to develop a very strong interior vortex 702 which can be
enhanced and
utilized with the introduction of diffuser air 304 through air slots 305.
[0046] Material classifier 20 is shown in a typical installation of a regrind
system 22
as depicted schematically in figures 3 and 4.
[0047] By way of example only and without limitation, a plastic regrind system
takes
existing plastic components or scrap from injection moulding machines or blow
moulding
machines and regrinds this plastic for later reuse. The plastic is introduced
into grinder 501
through raw material inlet 502 and via piping 511 is conveyed in an air
fluidized manner to
material classifier 20, wherein both coarse particles 106 and fine particles
107 enter material
classifier 20 along with dust of coarse, and wherein through the cyclonic
action of cyclone
100, the larger particles fall quickly to the cyclone outlet 103 and out
through air diffuser 300
and into air lock 400, where they are dropped into material container 504.
Depending upon
the amount of diffuser air 304 which one selects to enter through air slots
305, the lighter,
smaller granular particles as well as dust is carried upwardly with interior
vortex 702, up
through blower 200 and out through blower discharge 250. Therefore, larger
particles of a
certain size are discharged through air lock 400 and smaller particles of a
certain size are
discharged through blower discharge 250.
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[0048] In order to separate blower air 105 from fine particles 107 and dust
which also
may be entrained, a bag house 502 is employed, wherein the air and particles
discharged from
blower discharge 250 pass through plenum SOS and drop down through air filters
506
wherein air is discharged and fine granular material is collected in fines
containers 507.
[0049] In this manner a person skilled in the art will note that various
granular
materials can be classified using material classifier 20 including plastic
materials, grains,
sands, coffee, wood chips, rubber granular materials, fibre granular
materials, plastics from
metal, jute from wire, filaments and many other granular type materials too
numerous to list
here.
[0050] Further it has been found that by using a barometric damper (not shown
in the
drawings) to control the amount of diffuser air 304 one can compensate for
through put
variations such as material surges or variations in material through put
rates. The barometric
damper would have an upstream sensor placed prior to cyclone inlet 102 which
would adjust
diffuser air 304 amounts according to material through put.
Description of Alternate Embodiment
[0051] An alternate embodiment of the material classifier is shown in Figures
6, 7, 8
and 9 and is shown generally as material classifier 700 which operates in an
analogous
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fashion as material classifier 20 with the following modifications and
improvements to the
cyclone.
[0052] Material classifier 700 includes a conical top 720 having a top
diameter 712,
a cylindrical section 714 and a conical bottom section 710. It further
includes cyclone inlet
102 which can positioned at different inlet height 704 and/or different inlet
angles alpha 706.
In addition, conical bottom 710 may have a differing bottom outlet diameter
708 as shown
particularly in figure 8 in dashed lines being the larger bottom outlet
diameter 708 and the
solid lines being the smaller bottom outlet diameter 708.
[0053] Referring now to figure 9 which shows schematically the development of
the
interior vortex 702 which is rising upwardly and development of the exterior
or vortex 701
which is moving downwardly. The modifications to material classifier 700 will
now be
explained in regard to optimizing the development and strength of interior
vortex 702 which
carries out fines through blower discharge 250.
[0054] It has been found by trial and error that in order to encourage
development of
the updraft in interior vortex 702 and more efficient separation of coarse
particles 106 from
fine particles 107, a number of modifications to the cyclone have been shown
to help develop
a stronger interior vortex 702. In particular the inlet height 704 shown in
Figure 7 will aid
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in the development of interior vortex 702 as well as the inlet angle alpha 706
as shown in
figure 8 and figure 6 and as well by adding a conical top section 720 on top
of cylindrical
section 714, one also is able to enhance and aid the development of a strong
interior vortex
702.
[0055] The inventor has also found that by having a smaller bottom outlet
diameter
708 as shown in figure 8, one can also increase the updraft or the strength of
interior vortex
702 within material classifier 700.
[0056] By optimizing inlet height 704, inlet angle alpha 706, bottom outlet
diameter
708 as well as by the addition of a conical top section 720, one can customize
material
classifier 700 to separate the coarse particles 106 from fine particles 107.
[0057] It should be apparent to persons skilled in the arts that various
modifications
and adaptation ofthis structure described above are possible without departure
from the spirit
of the invention the scope of which defined in the appended claim.
