CA1315727C - Conveying apparatus and separation apparatus - Google Patents
Conveying apparatus and separation apparatusInfo
- Publication number
- CA1315727C CA1315727C CA000607800A CA607800A CA1315727C CA 1315727 C CA1315727 C CA 1315727C CA 000607800 A CA000607800 A CA 000607800A CA 607800 A CA607800 A CA 607800A CA 1315727 C CA1315727 C CA 1315727C
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- Canada
- Prior art keywords
- plate
- apertures
- fluid
- distribution
- separation apparatus
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
CONVEYING APPARATUS AND SEPARATION APPARATUS
Inventor: Christopher Philip Morris ABSTRACT OF THE DISCLOSURE
A conveying apparatus characterised by a distribution plate (10) having a plurality of apertures (12) therein whereby a fluid can flow through the plate, a conveying zone (22) disposed above said distribution plate (10) and fluid supply means for supplying a fluid to said conveying zone (22) through the distribution plate (10), wherein said distribution plate (10) is adapted to direct the fluid therethrough in a direction which has a component extending along a surface (14) of the plate, whereby a material disposed in the conveying zone is fluidised and is conveyed along said surface of the plate.
Inventor: Christopher Philip Morris ABSTRACT OF THE DISCLOSURE
A conveying apparatus characterised by a distribution plate (10) having a plurality of apertures (12) therein whereby a fluid can flow through the plate, a conveying zone (22) disposed above said distribution plate (10) and fluid supply means for supplying a fluid to said conveying zone (22) through the distribution plate (10), wherein said distribution plate (10) is adapted to direct the fluid therethrough in a direction which has a component extending along a surface (14) of the plate, whereby a material disposed in the conveying zone is fluidised and is conveyed along said surface of the plate.
Description
2 ~
This invention relates to an elukriator.
Conventionally, air-borne ma~er such as matter conveyed by a low pressure pneumatic conveyox is separated from the air stream by a mechanical devic~, such as a cyclone. These devices, however, are generally large and expensive items of equipment.
In GB-A-1,095,904 there is described an air filtering apparatus which is particularly suitable for removing ~ibre waste from an air stream. The apparatus has an inlet, an air outlet and a waste outlet. An air permeable screen is disposed between the inlet ~nd the air outlet; the air permeable screen is not permeable 'o the fibre was~e.
In GB-A-1,122,705 there is described an a~paratus for separating solid particles entrained in a gas stream. As with GB-A-1,095,90~ the apparatus includes an inlet, a gas outlet, a solid particle outlet, and a gas permeable screen disposed between the inlet and the gas outlet. The screen can be formed of a perforated sheet metal or a wire mesh.
Another apparatus for separating air~borne mat~er from an air stream is described in GB-A-1,575,175.
When designing this type of separation apparatus it is advantageous for the separator to be as small as possible in order to reduce manufacturing costs, and to reduce the amount of space taken up by the separator.
However, when the apparatus is made smaller the air-borne matter tends to accumulate on the screen and this increases the load on the fan forcing the air through the separator. This problem is solved in GB-A-1,575,175, where 1 3 ~L ~ rJ 2 ~
the structure of the separator is carefully selected to reduce to a minimum any accumulation on the screen.
Another type of separation apparatus, known as an elutriator is disclosed in EP-A-159890.
According to the present invention there is provided an elutriator for separating different grades of a material, comprising a first distribution means an elutriation zone disposed above the first distribution means, a fluid supply means for supplying a Eluid to said zone through the first distribution means, said first distribution means comprising two first distribution plates which diverge in an upward direction, each ~irst distribution plate being provided with first apertures which direct the fluid therethrough in a direction which has a component extending along a surface of the plate, and wherein, in use, the velocity of air delivered to the elutriation zone is greater -than the terminal velocity of at least one grade of the material to be separated.
Preferably, the first apertures are arranged at an acute angle to the plate; this angle is preferably 10 to ~0, more preferably 20 to 45.
Advantageously, the first distribution plate is arranged at an angle to the vertical which is substantially the same as the angle of the first apertures to the surface of the first plateO
This provides an upward air flow which is substantially vertical.
The arrangement is desirably such that the two first 13~5 ~7 plates are arranged symmetrically about a vertical plane with equal but opposite angles to said plane. A material outlet for high terminal velocity material may be provided between the plates.
In a particularly preferred con~truction selected areas of the first plate are provided with ~irst apertures having different angles to the surlace o~ the irst plate.
Desirably first and second areas are provided, each area extending substantially entirely across the first plate, said ~irst and ~econd areas being arranged alternately from one end of the first plate to the othar.
The first apertures in the first areas may be arran~ed at an angle of substantially 90 to the sur~ace of the plate (ie with no component along the surface of the plate), and the first apertures in the second areas may be arranged at an an~le substantially e~ual to the angle of inclination of the plate to the vertical (so that the resultant air flow through these areas is substantially vertical). This particular arrangement has been found to provide especially good results.
Another first distribution plate is preferably provided between said two first plates, above the material outlet for the high terminal velocity grades.
The percentage open area o~ the plates is preferably 4% to 12%, more preferably 8% to 9%, and most preferably substantially 8.6% of the total area of the plate.
Preferably the first apertures of the plate have a cross-sectional area in the range 20x106 sq. inches (about 13Ox10-6 - ,~
~ 3 .1~ ~ ri~ 2 ~
cm2) to lOOOxlO 6 s~. inches (about 6450xlO 6 cm~).
The thickness of the first plates may be in the range 20 thou to 40 thou (about 51xlO 3 cm to about 102xlO 3 cm), more preferably 28 -thou to 36 thou (abou-t 71xlO 3 cm to about 91xlO 3 cm).
The fluid supply means may comprise a fan.
The distribution device may provide a pressure drop across a first plate of between 0.5 inch to 2.5 inches gauge (approximately 1.25cm to 6.25cm), preferably about 1.5 inches gauge (approximately 1.88cm).
The elutriator may be fed from a fluid conveyor having a second distribution plate having a plurality of second apertures therein whereby a fluid can flow through the second plate, a conveying zone disposed above said second distribution plate, and second fluid supply means for supplying a fluid to said conveying zone through the second distribution plate, wherein said second apertures said second distribution plate is adapted to direct the fluid therethrough in a direction which has a component extending along a surface of the second plate, whereby a material disposed in the conveying zone is conveyed along said surface of the second plate.
The best results are obtained when the material disposed in the conveying zone is fluidised by the air stream.
Advantageously at least some of the second apertures extend through the plate at an acute angle to the surface of the plates.
Preferably the angle is in the range of 10 to 60 more preferably 20 to ~5.
~3~72~
The cross~sectional area of each second aperture may vary through the plate. Hcwever the minimum cross-sectional area of each aperture may be in the range 20 x 19 sq. inches (approximately 130 x 10~ cm2) to lO00 x 10~ sq.
inches (approximately 6450 x 10~ cm~, pref~rably 80 x 10 sq. inches (approximately 520 x 104 cm2) to 700 x lo-6 sq.
inches ~approximately 4520 x 10~ cm2) more preferably 170 x 10~ sq. inches (approximately 1100 x 10~ cm2) to 500 x 10~
sq. inches (approximately 3220 x 1o6 cm~), and most ~0 preferably 300 x lOfi sq. inches ~approximately 1940 x lo-G
cm2~ ~
Preferably the total area o~ the second apertures is in the range 1% to 12% of the total area of the second plake.
The thickness of the second plate is preferably in the range 5 though to 30 though (12.7 x 13~3cm to 77 x 10~3cm), more preferably 15 thou to 25 thou ~19.1 x 10~3cm to 63.8 x 103 cm), most preferably about 20 thou (51 x 10'3 cm).
The second plate may be any suitable material such as a plastics or metallic material. Preferably the second plate is stainless steel.
The second apertures in the second plate may be produced by any convenient method, such as punching, laser beam drilling or chemical milling. Photo-etching is the preferred method for forming the second apertures.
The second apertures may be oE any desired cross-sectional shape. However, it is preferred that the second apertures are of substantially circular or rectangular ~L31~27 cross-section.
Typically the fluid is a gaseous medium such as air.
The number of second apertures per square inch of plate can be varied widely. Typically between about 20 to 250l more preferably 20 to 100, apertures per square inch is useful in conveying apparatus. However, the preferred number of second apertures per square inch is about 40.
Advantageously the conveying apparatus further includes a first plenum chamber disposed below the second distribution plate, and the fluid supply means is arranged to deliver the fluid to the first plenum chamber. The fluid supply means is preferably a fan.
Desirably the conveyor includes a channel along which the material is conveyed, and the second distribu~ion plate may form at least part of the channel.
The channel may ~e of rectangular cross-section, U-shaped cross-section, V-shaped cross-section, or circular cross-section, for example.
It is pre~erred that the second distribution plate comprises at least a lower portion of the channel.
In an advantageous construction the channel comprises a base and side walls and at least part of the at least one side wall is provided with second apertures communica~ing with a second plenum chamber, which lS preferably in communication with first fluid withdrawal means.
It is preferable that the f irst f luid withdrawal means is the same as the second fluid supply means.
Advantageously the second apertures in the or each 13~5 7~
side wall are adap~ed to direct the f luid therethrough in a direction which has a component extending along the surface of the or each side wall. it is par-ticularly preferred that this direction is selected so that the fluid flows through second apertures in the or each side wall in a direction having a component which is opposed or at 90 to the forward direction in which the material is conveyed.
The second apertures in the or each side wall may have the same size and spacing as ~he second apertures in the second distribution plate, and may serve as a filter to prevent large particles being removed by the first fluid withdrawal means. Preferably, however, there are 200-300, more preerably, 240 holes per square inch on the ~ide wall.
Preferably a cover is provided over said conveyiny zone. The cover may be secured to, or integral wit~ ~he channel, and serves to prevent material being inadvertently discharged from the conveyor.
In one construction, the cover is air-porous. In this construction a third plenum chamber may be disposed above the cover. Second fluid withdrawal means may be provided in communication with the third plenum chamber; the second fluid withdrawal means may be a fan.
If desired the second fluid supply means may be the same as the third fluid withdrawal means.
The air-porous ~over may act as a filter to prevent large particles of dust being removed by the third fluid withdrawal means.
rdl ~ ~
However, the conveyor according to the invention does not create very much dust because the material is con~eyed in a relatively gentle manner compared with other types of conveying apparatus.
The conveying apparatus is particularly useful for conveying leaf material such as tea or tobacco. The conveying apparatus may also be used with a wide variety of ~ood products, for example, low density cereals. In this case the conveyor may act as the pretreatment zone described in EP-A-159890.
The elutriator is partlcularly suitable for separating grades of leaf material such as tea and tobacco, especially threshed tea and tobacco.
It should be noted that the material may comprise a mixture of two or more different substances (in which cass the term "grade" can be construed as referring to different substances~ or may comprise a single substance having a plurality of different grades. For example, in the elutriation of tobacco a heavier grade would comprise stem whilst a lighter grade would comprise leaf.
Both first and second apertures may be produced by any convenient method, for example, by punching, by laser beam drilling, or by chemical milling such as photo-etching.
Photo-etching is the preferred manu~ac~uring technique.
When the cross-sectional area of tha apertures varies through the plake then the above ~efined aperture cross-sectional areas should be understood to refer to the minimum area of the apertures through the plate.
~L33 ~j7~rl The apparatus described above may be used in a wide variety of applications. The invention is especially suitable for use with irregularly shaped low density material~, particularly ~ood, tobacco, paper and tea.
The apparatus ~ccording to the invention provides an elutriation apparatus which helps to prevent the material from accumulating on the screen. This is believed to be partly due to the improved turbule~ce provided by the apertured plate, and partly due to the substantially smooth surface of the plate.
The elutriation apparatus according to the invention is particularly useful for separating irregularly shaped low density materials~ such as tobacco, tea and paper, from air.
The particular advantage which the elutriation apparatus of the present invention has over the apparatus described in GB-A-1575175 is tha~ it creates extra turbulence around the plate which preven~s the airborne material from s~icking to the plate. Because of this the design parameters from the elutriation apparakus according to the present invention are not so critical as for the apparatus described in GB-A~1575175.
Re~erence is now made ~o the accompanying drawings, in which:-Figure 1 is a cross sectional view of a distribution plate for use in the invention;
Figure ~ is a schematic elevation in cross-section of a conveyiny apparatus according to the invention;
This invention relates to an elukriator.
Conventionally, air-borne ma~er such as matter conveyed by a low pressure pneumatic conveyox is separated from the air stream by a mechanical devic~, such as a cyclone. These devices, however, are generally large and expensive items of equipment.
In GB-A-1,095,904 there is described an air filtering apparatus which is particularly suitable for removing ~ibre waste from an air stream. The apparatus has an inlet, an air outlet and a waste outlet. An air permeable screen is disposed between the inlet ~nd the air outlet; the air permeable screen is not permeable 'o the fibre was~e.
In GB-A-1,122,705 there is described an a~paratus for separating solid particles entrained in a gas stream. As with GB-A-1,095,90~ the apparatus includes an inlet, a gas outlet, a solid particle outlet, and a gas permeable screen disposed between the inlet and the gas outlet. The screen can be formed of a perforated sheet metal or a wire mesh.
Another apparatus for separating air~borne mat~er from an air stream is described in GB-A-1,575,175.
When designing this type of separation apparatus it is advantageous for the separator to be as small as possible in order to reduce manufacturing costs, and to reduce the amount of space taken up by the separator.
However, when the apparatus is made smaller the air-borne matter tends to accumulate on the screen and this increases the load on the fan forcing the air through the separator. This problem is solved in GB-A-1,575,175, where 1 3 ~L ~ rJ 2 ~
the structure of the separator is carefully selected to reduce to a minimum any accumulation on the screen.
Another type of separation apparatus, known as an elutriator is disclosed in EP-A-159890.
According to the present invention there is provided an elutriator for separating different grades of a material, comprising a first distribution means an elutriation zone disposed above the first distribution means, a fluid supply means for supplying a Eluid to said zone through the first distribution means, said first distribution means comprising two first distribution plates which diverge in an upward direction, each ~irst distribution plate being provided with first apertures which direct the fluid therethrough in a direction which has a component extending along a surface of the plate, and wherein, in use, the velocity of air delivered to the elutriation zone is greater -than the terminal velocity of at least one grade of the material to be separated.
Preferably, the first apertures are arranged at an acute angle to the plate; this angle is preferably 10 to ~0, more preferably 20 to 45.
Advantageously, the first distribution plate is arranged at an angle to the vertical which is substantially the same as the angle of the first apertures to the surface of the first plateO
This provides an upward air flow which is substantially vertical.
The arrangement is desirably such that the two first 13~5 ~7 plates are arranged symmetrically about a vertical plane with equal but opposite angles to said plane. A material outlet for high terminal velocity material may be provided between the plates.
In a particularly preferred con~truction selected areas of the first plate are provided with ~irst apertures having different angles to the surlace o~ the irst plate.
Desirably first and second areas are provided, each area extending substantially entirely across the first plate, said ~irst and ~econd areas being arranged alternately from one end of the first plate to the othar.
The first apertures in the first areas may be arran~ed at an angle of substantially 90 to the sur~ace of the plate (ie with no component along the surface of the plate), and the first apertures in the second areas may be arranged at an an~le substantially e~ual to the angle of inclination of the plate to the vertical (so that the resultant air flow through these areas is substantially vertical). This particular arrangement has been found to provide especially good results.
Another first distribution plate is preferably provided between said two first plates, above the material outlet for the high terminal velocity grades.
The percentage open area o~ the plates is preferably 4% to 12%, more preferably 8% to 9%, and most preferably substantially 8.6% of the total area of the plate.
Preferably the first apertures of the plate have a cross-sectional area in the range 20x106 sq. inches (about 13Ox10-6 - ,~
~ 3 .1~ ~ ri~ 2 ~
cm2) to lOOOxlO 6 s~. inches (about 6450xlO 6 cm~).
The thickness of the first plates may be in the range 20 thou to 40 thou (about 51xlO 3 cm to about 102xlO 3 cm), more preferably 28 -thou to 36 thou (abou-t 71xlO 3 cm to about 91xlO 3 cm).
The fluid supply means may comprise a fan.
The distribution device may provide a pressure drop across a first plate of between 0.5 inch to 2.5 inches gauge (approximately 1.25cm to 6.25cm), preferably about 1.5 inches gauge (approximately 1.88cm).
The elutriator may be fed from a fluid conveyor having a second distribution plate having a plurality of second apertures therein whereby a fluid can flow through the second plate, a conveying zone disposed above said second distribution plate, and second fluid supply means for supplying a fluid to said conveying zone through the second distribution plate, wherein said second apertures said second distribution plate is adapted to direct the fluid therethrough in a direction which has a component extending along a surface of the second plate, whereby a material disposed in the conveying zone is conveyed along said surface of the second plate.
The best results are obtained when the material disposed in the conveying zone is fluidised by the air stream.
Advantageously at least some of the second apertures extend through the plate at an acute angle to the surface of the plates.
Preferably the angle is in the range of 10 to 60 more preferably 20 to ~5.
~3~72~
The cross~sectional area of each second aperture may vary through the plate. Hcwever the minimum cross-sectional area of each aperture may be in the range 20 x 19 sq. inches (approximately 130 x 10~ cm2) to lO00 x 10~ sq.
inches (approximately 6450 x 10~ cm~, pref~rably 80 x 10 sq. inches (approximately 520 x 104 cm2) to 700 x lo-6 sq.
inches ~approximately 4520 x 10~ cm2) more preferably 170 x 10~ sq. inches (approximately 1100 x 10~ cm2) to 500 x 10~
sq. inches (approximately 3220 x 1o6 cm~), and most ~0 preferably 300 x lOfi sq. inches ~approximately 1940 x lo-G
cm2~ ~
Preferably the total area o~ the second apertures is in the range 1% to 12% of the total area of the second plake.
The thickness of the second plate is preferably in the range 5 though to 30 though (12.7 x 13~3cm to 77 x 10~3cm), more preferably 15 thou to 25 thou ~19.1 x 10~3cm to 63.8 x 103 cm), most preferably about 20 thou (51 x 10'3 cm).
The second plate may be any suitable material such as a plastics or metallic material. Preferably the second plate is stainless steel.
The second apertures in the second plate may be produced by any convenient method, such as punching, laser beam drilling or chemical milling. Photo-etching is the preferred method for forming the second apertures.
The second apertures may be oE any desired cross-sectional shape. However, it is preferred that the second apertures are of substantially circular or rectangular ~L31~27 cross-section.
Typically the fluid is a gaseous medium such as air.
The number of second apertures per square inch of plate can be varied widely. Typically between about 20 to 250l more preferably 20 to 100, apertures per square inch is useful in conveying apparatus. However, the preferred number of second apertures per square inch is about 40.
Advantageously the conveying apparatus further includes a first plenum chamber disposed below the second distribution plate, and the fluid supply means is arranged to deliver the fluid to the first plenum chamber. The fluid supply means is preferably a fan.
Desirably the conveyor includes a channel along which the material is conveyed, and the second distribu~ion plate may form at least part of the channel.
The channel may ~e of rectangular cross-section, U-shaped cross-section, V-shaped cross-section, or circular cross-section, for example.
It is pre~erred that the second distribution plate comprises at least a lower portion of the channel.
In an advantageous construction the channel comprises a base and side walls and at least part of the at least one side wall is provided with second apertures communica~ing with a second plenum chamber, which lS preferably in communication with first fluid withdrawal means.
It is preferable that the f irst f luid withdrawal means is the same as the second fluid supply means.
Advantageously the second apertures in the or each 13~5 7~
side wall are adap~ed to direct the f luid therethrough in a direction which has a component extending along the surface of the or each side wall. it is par-ticularly preferred that this direction is selected so that the fluid flows through second apertures in the or each side wall in a direction having a component which is opposed or at 90 to the forward direction in which the material is conveyed.
The second apertures in the or each side wall may have the same size and spacing as ~he second apertures in the second distribution plate, and may serve as a filter to prevent large particles being removed by the first fluid withdrawal means. Preferably, however, there are 200-300, more preerably, 240 holes per square inch on the ~ide wall.
Preferably a cover is provided over said conveyiny zone. The cover may be secured to, or integral wit~ ~he channel, and serves to prevent material being inadvertently discharged from the conveyor.
In one construction, the cover is air-porous. In this construction a third plenum chamber may be disposed above the cover. Second fluid withdrawal means may be provided in communication with the third plenum chamber; the second fluid withdrawal means may be a fan.
If desired the second fluid supply means may be the same as the third fluid withdrawal means.
The air-porous ~over may act as a filter to prevent large particles of dust being removed by the third fluid withdrawal means.
rdl ~ ~
However, the conveyor according to the invention does not create very much dust because the material is con~eyed in a relatively gentle manner compared with other types of conveying apparatus.
The conveying apparatus is particularly useful for conveying leaf material such as tea or tobacco. The conveying apparatus may also be used with a wide variety of ~ood products, for example, low density cereals. In this case the conveyor may act as the pretreatment zone described in EP-A-159890.
The elutriator is partlcularly suitable for separating grades of leaf material such as tea and tobacco, especially threshed tea and tobacco.
It should be noted that the material may comprise a mixture of two or more different substances (in which cass the term "grade" can be construed as referring to different substances~ or may comprise a single substance having a plurality of different grades. For example, in the elutriation of tobacco a heavier grade would comprise stem whilst a lighter grade would comprise leaf.
Both first and second apertures may be produced by any convenient method, for example, by punching, by laser beam drilling, or by chemical milling such as photo-etching.
Photo-etching is the preferred manu~ac~uring technique.
When the cross-sectional area of tha apertures varies through the plake then the above ~efined aperture cross-sectional areas should be understood to refer to the minimum area of the apertures through the plate.
~L33 ~j7~rl The apparatus described above may be used in a wide variety of applications. The invention is especially suitable for use with irregularly shaped low density material~, particularly ~ood, tobacco, paper and tea.
The apparatus ~ccording to the invention provides an elutriation apparatus which helps to prevent the material from accumulating on the screen. This is believed to be partly due to the improved turbule~ce provided by the apertured plate, and partly due to the substantially smooth surface of the plate.
The elutriation apparatus according to the invention is particularly useful for separating irregularly shaped low density materials~ such as tobacco, tea and paper, from air.
The particular advantage which the elutriation apparatus of the present invention has over the apparatus described in GB-A-1575175 is tha~ it creates extra turbulence around the plate which preven~s the airborne material from s~icking to the plate. Because of this the design parameters from the elutriation apparakus according to the present invention are not so critical as for the apparatus described in GB-A~1575175.
Re~erence is now made ~o the accompanying drawings, in which:-Figure 1 is a cross sectional view of a distribution plate for use in the invention;
Figure ~ is a schematic elevation in cross-section of a conveyiny apparatus according to the invention;
3 3 ~ 5 rl ~ r~
Figure 3 is a cross section of through the aonveying apparatus shown in Figure 1;
Figure 4 is a cross sectional view of a conveying apparatus according to the invention, showing the configuration at a bend;
Figure 5 is a side elevation of a conveying apparatus according to the in~ention pxovided with an inclined portion;
Figure 6 is a side elevation of a conveyor according to the invention showing the discharge point;
Figure 7 is a cross sectional view of an alternate embodiment of a conveying apparatus according to the invention;
Figure 8 is an end elevation of an elutriator according to the invention;
Figure 9 is a side elevation of the elutriakor shown;
and Figure 10 is an enlarged view of the diverging plates shown in Figures 8 and 9.
Referring to Figure 1 a distribution device according to the invention comprises a plate lO having a plurality of apertures 12 (of which only one is shown) extending between upper and lower surfaces 14 and 16 thereof.
The apertures 12 are disposed at an acute angle O to 25 the upper and lower surfaces 14 and 16; the angle O i5 preferably about 45. The precise choice of the size of the angle 0 depends upon the particular application of the plate 10.
11 31 572~
The general direction A of air flowiny upwardly through the plate 10 will ba at the angle O to ~he surfaces 14 and 16. The air flow direction A can be broken into two orthogonal directional components B and C; the directional component B is substantially parallel to the surfaces 14 and 16, whilst the directional component C is substantially transverse to the surfaces 14 and 16.
Thus, if air is blown upwardly through the plate 10, then any material on the upper surface 14 will have motion impar~ed to it in directions B and C. The directional component C can a~t to fluidise the ma~erial, whilst the directional component ~ can a~t to conve~ the material forwardO
It will be observed that the apertures 17 comprise upper and lower components l~a and l~b. This arrangement is produced when the apertures are produced by photo-etching techni~ues involving etching the apertures from both sides of the plate. In this case the angle 0 of the apertures 12 can be considered as the angle between the surface 14 of the plate 10 and the line extending between the centres of the apertures 12a and 12b in the surfaces 14 and 16~
In Figures 2 to 7 a conveying apparatus 20 comprises a conveying channel 22 de~ined by a base fo~med of a plurality of juxtapo~itioned distribution plates 10 and side walls 24 upstanding from the plates 10. The channel 22 defines a conveying zone for material to be conveyed.
A first plenum chamber 26 is disposed beneath the i 3 1 !~ ~ 2 ~
plates 10 and is provided with an inlet 28 which can be connected to an air supply ~an 2~. A cover 30 is disposed on top of the side walls ~.
When the material to be conveyed is placed in the channel 22 it is fluidised by air supplied by the fan passing through the apertures 12 o~ the plates 10.
Furthermore~ the air applies a ~orce to the materlal having the directional component B which causes the material to be conveyed along the surface 14 of the plate 10.
A lower portion of each side wall 24 is provided with a plurality of apertures 25. The apertures 25 are similar to the apertures 12 and they extend through the side walls 24.
A second plenum chamber 27 is arranged on the opposite side wall of the side walls 24 to the conveying zone. ~he plenum chamber is in fluid communication with the fan 2g, so that the fan 29 acts to withdraw air from the conveying channel 22 through the apertures 25. The aperture~ 25 are arranged at such an angle that air flowing through the apertures 25 into the second plenum chamber 27 flows in a direction which has a component opposite to the direction B.
More than one fan 29 can be provided, depending on the length of the conveyor 20; in Figure l two ~ans 29 are 2S provided. Each fan 29 is provided with a dust collection duct 31 having a dust collection bag or bin 33 secured to the free end thereofj the arrangement of this type of duct 31 and bin 33 is well known.
1 31 ~ ~ ~ 7 The convayor 20 has an inlet 21 and an outlet 23 ~see Figure G). .~ further dust collection duct 31 and bin 33 can be provided at the outlet.
The bin 33 acts to filter dust from the air fed from the plenum chamber 27 to the fan 29.
Figure 4 shows the configuration of the conveyor 20 at a bend. It will be observed that the plate 10 is provided with two portions lOa and lOb, with the portion lOb being arranged at an angle to the horizontal. The arrangement shown in Figure 4 would be suitable for a right-hand bend, assuming the direction of conveying is into the plane of the drawing.
Fiyure 5 shows a conveyor 20 having a inclined portion 39, so that the material to be conveyed can be conveyed up an inclination.
Figure 7 shows another embodiment in which a third plenum chamber 34 replaces the second plenum chamber 27 shown in Figures 1 to 5. The third plenum chamber 34 is disposed above the cover 30, and the cover is provided with apertures 32. The third plenum chamber 34 is provided with an outlet 36 which can be connected to the fan 2~.
In the above e~bodi~ents the perforated cover 30 or perforated side walls 24 act as a filter to remove dust from the conveying channel 22, without removing the large particles. This dust is, in turn, collected at the dust bins 33.
In ~igures 8 and 9 an elutriator is shown schematically. The elutriator includes an elutxiation zone ~r~27 1~
100 arrange~ above two of said distributlon plates 10. It will be appreciated tha~ more than two plates 10 can be employed. The plates 10 are arranged substantially at the angle 0 to the vertical.
The elutriator is provided with a material inlet 102;
a high terminal velocity material outlet 104 is disposed between the plates 10, and a low terminal velocity material outlet 106 is provided at the top of a hood 108. The hood 108 is disposed over the plates 10 and the elutriation zone 10 10~.
A conveyor 107 is disposed below the material outlet 106. The conveyor 106 may be a conveyor as shown in Figure 2. Also, an air lock (not shown), such as a rotary air lock, may be disposed at the material outlet 104.
A plenum chamber 110 is disposed on the opposite sides o~ each pair of plates 10 to the elutriation zone 100.
Each plenum chamber 110 is provided with an inlet duct 112 which can be connected to a fan 113. The fan 113 delivers air to the plenum cha~bers 110 which enters the elutriation zone 100 through the plates 10. A filter 1~5 (which can be a mesh) is disposed in the duct 113.
The outlet 106 may also be connected to the fan 113 to draw air from the elutriation zone 100.
~he general principles behind the ope.rati.on of this type of elutriator are described in detail in EP~A-159890.
The air supply fan 113 supplies air at a rate such that the velocity of air in the elutriation zone loO is greater than the terminal velocity of the material which it ~3~72~
is desired to ~btain as top product in the ~utlet 106. Th~
material of greater terminal veloci~y falls to the outlet 104. The plates 10 are adapted to provide a substantially uniform flow rate of air to the elutriation zone 100 in order to reduce the air flow rate r~quired to effect separation (as described in EP-A-15~890).
One of the separators 230 is disposed in a duct 117 which ex~ends between the outlet 106 and the fan 113. The top product is discharged through the outlet 221 o~ the separator ~30.
Addi~ional distribution plates 10 are disposed above the material outlet 104 between the diverging plates 10.
Another plenum chamber 120 i5 defined within the additional distribution plates 10, and the chamber 120 may be supplied by the fan 113 through the ~uct 112;
alt2rnatively an additional fan (not shown) can be proYided .
The apertures of the diverging plates 10 can be arranged into two types of area each extending substantially across the entire width of the plate 10, and each area being arranged alternately from the lower end of the plates 10 to the upper end; in Figures 8 and 9 the areas are designated A~ and A2 respectively.
In axea Al the apertures 24 in each plate 10 are arranged at the angle O to the surface of the plate 10.
Thus air ~lowing through the aperture~ 24 of the plate 10 in the area A~ flows substantially vertically upwards to the elutriation zone 100, as shown by arrows D.
~ 3 ~ ~j P~J 2 ~
In area A2 the apertures 24 in ~ach plate 10 are arranged at substantially a 90 angle to ~he. sur~ace of the plate lO. Thus air flowing through the apertures 24 of the plate lO in the area A2 flow~ substantially orthogonally through the plate 10 ~o the elutriation zone, in the direction E.
The areas Al and ~ can, if desired, ~lso be provided on the additional plates 10.
Figure 3 is a cross section of through the aonveying apparatus shown in Figure 1;
Figure 4 is a cross sectional view of a conveying apparatus according to the invention, showing the configuration at a bend;
Figure 5 is a side elevation of a conveying apparatus according to the in~ention pxovided with an inclined portion;
Figure 6 is a side elevation of a conveyor according to the invention showing the discharge point;
Figure 7 is a cross sectional view of an alternate embodiment of a conveying apparatus according to the invention;
Figure 8 is an end elevation of an elutriator according to the invention;
Figure 9 is a side elevation of the elutriakor shown;
and Figure 10 is an enlarged view of the diverging plates shown in Figures 8 and 9.
Referring to Figure 1 a distribution device according to the invention comprises a plate lO having a plurality of apertures 12 (of which only one is shown) extending between upper and lower surfaces 14 and 16 thereof.
The apertures 12 are disposed at an acute angle O to 25 the upper and lower surfaces 14 and 16; the angle O i5 preferably about 45. The precise choice of the size of the angle 0 depends upon the particular application of the plate 10.
11 31 572~
The general direction A of air flowiny upwardly through the plate 10 will ba at the angle O to ~he surfaces 14 and 16. The air flow direction A can be broken into two orthogonal directional components B and C; the directional component B is substantially parallel to the surfaces 14 and 16, whilst the directional component C is substantially transverse to the surfaces 14 and 16.
Thus, if air is blown upwardly through the plate 10, then any material on the upper surface 14 will have motion impar~ed to it in directions B and C. The directional component C can a~t to fluidise the ma~erial, whilst the directional component ~ can a~t to conve~ the material forwardO
It will be observed that the apertures 17 comprise upper and lower components l~a and l~b. This arrangement is produced when the apertures are produced by photo-etching techni~ues involving etching the apertures from both sides of the plate. In this case the angle 0 of the apertures 12 can be considered as the angle between the surface 14 of the plate 10 and the line extending between the centres of the apertures 12a and 12b in the surfaces 14 and 16~
In Figures 2 to 7 a conveying apparatus 20 comprises a conveying channel 22 de~ined by a base fo~med of a plurality of juxtapo~itioned distribution plates 10 and side walls 24 upstanding from the plates 10. The channel 22 defines a conveying zone for material to be conveyed.
A first plenum chamber 26 is disposed beneath the i 3 1 !~ ~ 2 ~
plates 10 and is provided with an inlet 28 which can be connected to an air supply ~an 2~. A cover 30 is disposed on top of the side walls ~.
When the material to be conveyed is placed in the channel 22 it is fluidised by air supplied by the fan passing through the apertures 12 o~ the plates 10.
Furthermore~ the air applies a ~orce to the materlal having the directional component B which causes the material to be conveyed along the surface 14 of the plate 10.
A lower portion of each side wall 24 is provided with a plurality of apertures 25. The apertures 25 are similar to the apertures 12 and they extend through the side walls 24.
A second plenum chamber 27 is arranged on the opposite side wall of the side walls 24 to the conveying zone. ~he plenum chamber is in fluid communication with the fan 2g, so that the fan 29 acts to withdraw air from the conveying channel 22 through the apertures 25. The aperture~ 25 are arranged at such an angle that air flowing through the apertures 25 into the second plenum chamber 27 flows in a direction which has a component opposite to the direction B.
More than one fan 29 can be provided, depending on the length of the conveyor 20; in Figure l two ~ans 29 are 2S provided. Each fan 29 is provided with a dust collection duct 31 having a dust collection bag or bin 33 secured to the free end thereofj the arrangement of this type of duct 31 and bin 33 is well known.
1 31 ~ ~ ~ 7 The convayor 20 has an inlet 21 and an outlet 23 ~see Figure G). .~ further dust collection duct 31 and bin 33 can be provided at the outlet.
The bin 33 acts to filter dust from the air fed from the plenum chamber 27 to the fan 29.
Figure 4 shows the configuration of the conveyor 20 at a bend. It will be observed that the plate 10 is provided with two portions lOa and lOb, with the portion lOb being arranged at an angle to the horizontal. The arrangement shown in Figure 4 would be suitable for a right-hand bend, assuming the direction of conveying is into the plane of the drawing.
Fiyure 5 shows a conveyor 20 having a inclined portion 39, so that the material to be conveyed can be conveyed up an inclination.
Figure 7 shows another embodiment in which a third plenum chamber 34 replaces the second plenum chamber 27 shown in Figures 1 to 5. The third plenum chamber 34 is disposed above the cover 30, and the cover is provided with apertures 32. The third plenum chamber 34 is provided with an outlet 36 which can be connected to the fan 2~.
In the above e~bodi~ents the perforated cover 30 or perforated side walls 24 act as a filter to remove dust from the conveying channel 22, without removing the large particles. This dust is, in turn, collected at the dust bins 33.
In ~igures 8 and 9 an elutriator is shown schematically. The elutriator includes an elutxiation zone ~r~27 1~
100 arrange~ above two of said distributlon plates 10. It will be appreciated tha~ more than two plates 10 can be employed. The plates 10 are arranged substantially at the angle 0 to the vertical.
The elutriator is provided with a material inlet 102;
a high terminal velocity material outlet 104 is disposed between the plates 10, and a low terminal velocity material outlet 106 is provided at the top of a hood 108. The hood 108 is disposed over the plates 10 and the elutriation zone 10 10~.
A conveyor 107 is disposed below the material outlet 106. The conveyor 106 may be a conveyor as shown in Figure 2. Also, an air lock (not shown), such as a rotary air lock, may be disposed at the material outlet 104.
A plenum chamber 110 is disposed on the opposite sides o~ each pair of plates 10 to the elutriation zone 100.
Each plenum chamber 110 is provided with an inlet duct 112 which can be connected to a fan 113. The fan 113 delivers air to the plenum cha~bers 110 which enters the elutriation zone 100 through the plates 10. A filter 1~5 (which can be a mesh) is disposed in the duct 113.
The outlet 106 may also be connected to the fan 113 to draw air from the elutriation zone 100.
~he general principles behind the ope.rati.on of this type of elutriator are described in detail in EP~A-159890.
The air supply fan 113 supplies air at a rate such that the velocity of air in the elutriation zone loO is greater than the terminal velocity of the material which it ~3~72~
is desired to ~btain as top product in the ~utlet 106. Th~
material of greater terminal veloci~y falls to the outlet 104. The plates 10 are adapted to provide a substantially uniform flow rate of air to the elutriation zone 100 in order to reduce the air flow rate r~quired to effect separation (as described in EP-A-15~890).
One of the separators 230 is disposed in a duct 117 which ex~ends between the outlet 106 and the fan 113. The top product is discharged through the outlet 221 o~ the separator ~30.
Addi~ional distribution plates 10 are disposed above the material outlet 104 between the diverging plates 10.
Another plenum chamber 120 i5 defined within the additional distribution plates 10, and the chamber 120 may be supplied by the fan 113 through the ~uct 112;
alt2rnatively an additional fan (not shown) can be proYided .
The apertures of the diverging plates 10 can be arranged into two types of area each extending substantially across the entire width of the plate 10, and each area being arranged alternately from the lower end of the plates 10 to the upper end; in Figures 8 and 9 the areas are designated A~ and A2 respectively.
In axea Al the apertures 24 in each plate 10 are arranged at the angle O to the surface of the plate 10.
Thus air ~lowing through the aperture~ 24 of the plate 10 in the area A~ flows substantially vertically upwards to the elutriation zone 100, as shown by arrows D.
~ 3 ~ ~j P~J 2 ~
In area A2 the apertures 24 in ~ach plate 10 are arranged at substantially a 90 angle to ~he. sur~ace of the plate lO. Thus air flowing through the apertures 24 of the plate lO in the area A2 flow~ substantially orthogonally through the plate 10 ~o the elutriation zone, in the direction E.
The areas Al and ~ can, if desired, ~lso be provided on the additional plates 10.
Claims (20)
1. An elutriator for separating different grades of leaf material, comprising a first distribution means, an elutriation zone disposed above the first distribution means, a first fluid supply means for supplying a fluid to said zone through the distribution means, said first distribution means comprising two first distribution plates which diverge in an upward direction, each first distribution plate being provided with first apertures which direct the fluid therethrough in a direction which has a component extending along a surface of the plate, wherein, in use, the velocity of fluid delivered to the elutriation zone is greater than the terminal velocity of at least one grade of the material to be separated.
2. An elutriator according to claim 1, wherein first and second areas of said plate are provided with said first apertures having different angles to the surface of the plate.
3. An elutriator according to claim 2, wherein the first apertures of the plate have a cross-sectional area in the range 20x10-6 sq. inches (about 130x10-6 cm2) to 1000x10-6 sq. inches (about 6450x10-6 cm2).
4. An elutriator according to claim 3, wherein first and second areas are provided on the first distribution plates, each area extending substantially entirely across the plate, said first and second areas being arranged alternately from one end of the plate to the other.
5. An elutriator according to claim 4, wherein the first areas are arranged at an angel of substantially 90° to the surface of the plate, and the second areas are arranged at an angle substantially equal to the angle of inclination of the plate to the vertical.
6. An elutriator according to claim 5, wherein another first distribution plate is provided between said two first distribution plates above a material outlet for the high terminal velocity grades of the material to be separated.
7. A separation apparatus comprising the elutriator as in claim 1, and further comprising a conveying apparatus having a second distribution plate having a plurality of second apertures therein whereby a fluid can flow through the plate, a conveying zone disposed above said second distribution plate, and second fluid supply means for supplying a fluid to said conveying zone through the second distribution plate, wherein said second apertures of said second distribution plate direct the fluid therethrough in a direction which has a component extending along a surface of the second plate, whereby a material disposed in the conveying zone is fluidised and is conveyed along said surface of the second plate.
8. A separation apparatus according to claim 7, wherein the second apertures extend through the second plate at an angle to said surface of the second plate.
9. A separation apparatus according to claim 8, wherein said angle is in the range of substantially 10° to substantially 60°, preferably substantially 20° to substantially 45°.
10. A separation apparatus according to claim 7, wherein the cross-sectional area of each second aperture is in the range of substantially 20x10-6 sq. inches (approximately 130x10-6 cm2) to substantially 1000x10-6 sq. inches (approximately 6450x10-6 cm2), and the total area of the second apertures is in the range of substantially 1% to substantially 12% of the total area of the second plate.
11. A separation apparatus according to claim 7, wherein the conveying apparatus further includes a channel having a base which includes the second distribution plate, and side walls extending upwardly from the base.
12. A separation apparatus according to claim 11, wherein at least part of at least one side wall is provided with second apertures communicating with a second plenum chamber which is in communication with first fluid withdrawal means.
13. A separation apparatus according to claim 11, wherein the first fluid withdrawal means comprises the second fluid supply means.
14. A separation apparatus according to claim 12, wherein the second apertures in the or each side wall are adapted to direct the fluid therethrough in a direction which has a component extending along the surface of the or each side wall.
15. A separation apparatus according to claim 14, wherein said direction is selected so that the fluid flows through the second apertures in the or each side wall in a direction having a component which is opposed to the forward direction in which the material is conveyed.
16. A separation apparatus according to claim 7, wherein a first plenum chamber disposed below the second distribution plate and a cover disposed over the second distribution plate.
17. A separation apparatus according to claim 16, wherein the cover is provided with a plurality of second apertures.
18. A separation apparatus according to claim 17, having a third plenum chamber disposed above the cover.
19. A separation apparatus according to claim 18, characterised by second fluid withdrawal means which is in fluid communication with the third plenum chamber for withdrawing fluid from the third plenum chamber.
20. A separation apparatus according to claim 7, wherein the cross-sectional area of each second aperture of the second distribution plate is largest at the surface of the plate and is smallest at a point within the plate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000607800A CA1315727C (en) | 1989-08-08 | 1989-08-08 | Conveying apparatus and separation apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000607800A CA1315727C (en) | 1989-08-08 | 1989-08-08 | Conveying apparatus and separation apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1315727C true CA1315727C (en) | 1993-04-06 |
Family
ID=4140428
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000607800A Expired - Fee Related CA1315727C (en) | 1989-08-08 | 1989-08-08 | Conveying apparatus and separation apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1315727C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3067228A1 (en) * | 2015-02-23 | 2016-09-14 | Climecon OY | Steering nozzle of an air flow and a supply air device |
-
1989
- 1989-08-08 CA CA000607800A patent/CA1315727C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3067228A1 (en) * | 2015-02-23 | 2016-09-14 | Climecon OY | Steering nozzle of an air flow and a supply air device |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |