US3767045A - Closed circuit multi-stage air classifier - Google Patents

Closed circuit multi-stage air classifier Download PDF

Info

Publication number
US3767045A
US3767045A US00125140A US3767045DA US3767045A US 3767045 A US3767045 A US 3767045A US 00125140 A US00125140 A US 00125140A US 3767045D A US3767045D A US 3767045DA US 3767045 A US3767045 A US 3767045A
Authority
US
United States
Prior art keywords
coarse
chamber
particle separator
air
separator
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.)
Expired - Lifetime
Application number
US00125140A
Other languages
English (en)
Inventor
P Voelskow
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siempelkamp Giesserei KG
Original Assignee
Siempelkamp Giesserei KG
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Siempelkamp Giesserei KG filed Critical Siempelkamp Giesserei KG
Application granted granted Critical
Publication of US3767045A publication Critical patent/US3767045A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
    • B07B7/00—Selective separation of solid materials carried by, or dispersed in, gas currents
    • B07B7/08—Selective separation of solid materials carried by, or dispersed in, gas currents using centrifugal force

Definitions

  • ABSTRACT A closed-circuit air classifier for comminuted and particulate materials, especially wood fibers, sawdust, pulverized-wood particles and the like, which comprises a coarse air classifier and a fine classifier, each of which is provided with respective fan or whizzer blades for suspending or entraining the particles with respective air streams.
  • the inlet of the coarse air classifier is connected to the outlet of the fine air classifier and is provided with a pneumatic gate through which the material to be classified is introduced into the system.
  • the outlet of the coarse classifier is connected to the inlet of the fine classifier.
  • the present invention relates to air classifiers and, more particularly, to an air classifier of the type in which a stream of gas, generally air, entrains a particulate material to permit relatively coarse particles to sediment or deposit under gravitational and/or centrifugal force at one collection point while the lowergravity particles are carried by the gas to another collection point; more particularly, the invention relates to a closed-circuit air classifier enabling the collection of relatively heavy and relatively light particles of comminuted wood, e.g. for the preparation of pressed board.
  • the pressed board may have a layer of fine particles disposed along the opposite sides of a layer of coarse particles to improve the texture, moisture resistance and associated properties of the finished product.
  • a plant for the production of pressed board may, therefore, include dispensing devices for wood particles of various sizes, comminution apparatus, (e.g. mills for producing wood particles) and classifying apparatus for separating the milled wood products into particles of the desired size.
  • separating systems have been provided for classifying particles, in the pressed-board industry and elsewhere. For example, it is possible to separate particulate materials by their size using sieves or by their mass using gravitational phenomena. For example, cyclones may be used to remove particles of a particular size from a stream of air or other fluid in which the particles are entrained. Other separating systems make use of hydraulic, sedimentation and analogous techniques.
  • Such air classifiers require long columns, high-power blowers to generate the rising stream of air, and at least one cyclone-type separator to remove fine particles from the air before it is released in the atmosphere.
  • at least one filter is therefore required as well.
  • the cost of such systems is relatively high and the operating costs always prohibitive. More specifically, it has been found that the blower dimensioned are governed by the high flow resistance of the cyclon/filter combination and the added blower cost is accompanied by higher power requirements.
  • centrifugal air classifiers which enable the air-classification chamher to be reduced to a much smaller volume because of the higher air velocity and the lower losses in transferring energy from the fan or whizzer blades to the particles.
  • centrifugal air classifiers which enable the air-classification chamher to be reduced to a much smaller volume because of the higher air velocity and the lower losses in transferring energy from the fan or whizzer blades to the particles.
  • cyclones, filters and the like at the output side to prevent contaminating the atmosphere.
  • Still another object, of equal importance, is to provide an apparatus for the separation of a solid mix into particles of various sizes which has small spatial requirements, is of relatively inexpensive manufacture and most importantly does not contaminate the atmosphere.
  • Still another object, of equal importance, is to provide an apparatus for the separation of a solid mix into particles of various sizes which has small spatial requirements, is of relatively inexpensive manufacture and most importantly does not contaminate the atmosphere.
  • an air pneumatic classifier which comprises two air classifiers or separators connected in series and forming a closed circuit, including at least one coarse classifier and at least one fine classifier respectively having discharge gates through which the coarse and fine fractions can respectively be removed.
  • the outlet of the discharge side of the coarse classifier is connected to the intake side or inlet of the fine classifier and the discharge or outlet side of the latter is connected to the intake or inlet side of the coarse classifier by suitable conduits forming the closed circuit.
  • Each of the classifiers according to the present invention comprises a blower chamber and a classification chamber in succession and provided with air or gas displacement members, preferably fans, adapted to drive the classification air or gas through the seriesconnected classifier chamber or to induce (by generating negative or low pressures) the flow of classifying air through the system.
  • the cycle is closed off from the atmosphere but at least along some point of the circulation path, a gate is provided to admit the solids to be separated.
  • the rotors of the two units may be driven in the same sense in which case the conduit means may form with the classification units, an oval cycle; alternatively, the rotors of the units are driven in opposite senses and it has been found to be advantageous, in this case, to connect the conduits to these units in a figure-8 pattern.
  • the fine separator will be provided with a rotor which is longer and of larger diameter than the coarse-separator rotor and the classifying-air stream is directed at the coarse separator rotor with a higher radial speed than that of the gases directed at the fine-separator rotor.
  • the particles in the coarse separator are subjected to a lesser tangential acceleration, thereby permitting the larger particles to deposit from the air stream while the lighter particles are entrained with the radially inflowing air.
  • This gate can be in the form of a valve alternately open to the atmosphere and the closed circuit.
  • the coarse separator is provided, in its classification chamber, with guide elements for the air stream entering the chamber and orienting this stream at an angle to the radial and axial directions against the coarseparticle rotor, i.e. in a generally spiral direction. While it is possible within the present framework to direct the classifying airstream tangentially against the coarseseparator rotor, it has been found that the former technique is most desirable. In either case, the light particles are entrained in a circular-force field with the incoming stream working radially inwardly against the centrifugal forces generated by the rotor and eventually being transformed into an outwardly moving stream from which the particles have been eliminated and entraining primarily the heavier particles.
  • the guide elements may be formed as openings or passages between blades of a stator-blade ring disposed adjacent the coarse separation chamber.
  • the return conduit which connects the discharge side of the coarse separator to the intake side of the fine separator opens tangentially into the classification chamber of the latter.
  • the particles entrained in the classifying air are in large measure cast by centrifugal force against the walls of the housing and are guided to the discharge gate. Only the finest particles therefore remain in the air which is fed back from this separator.
  • the inlet conduit opens into the coarse separator at a housing portion which is rotationally symmetrical and coaxial withthe separating chamber.
  • this chamber is frustoconically divergent in the direction of the separating chamber to a diameter equal to that of the separating chamber. Because of this rotationally symmetrical configuration of the inlet chamber, it is possible to provide in the latter distribution blades or fans which rotate about the axis of the rotor and serve to distribute the particulate or comminuted material uniformly over the circumference of the chamber. It prevents buildup of the comminuted material and enables the guide surfaces to operate more effectively and more uniformly.
  • the drive motor of at least the coarse-particle rotor is of adjustable speed and appropriate adjusting means is provided for the same.
  • the rotor of the fine separator may also be controlled although this is not essential.
  • one or both of the conduits connecting the two units are provided with a flap damper or other adjustable flow-control member which also serves to regulate the particle-size fraction connected in each chamber.
  • asecondary flow or air is provided to constitute an air gate blocking the transfer of solids across a partition separating the collection chamber from the blower chamber.
  • the excess air supplied by an external source of compression air may be vented to the atmosphere via a filter sack.
  • the present system operates in accordance with principles of both centrifugal and pneumatic classification, in that the rotors of the units may be axial intake, radial outflow blowers provided with cylindrical cages of rods or bars against which the air stream containing the particles is directed.
  • the bars constitute centrifugal fans in their own right and cast light particles outwardly while deflecting heavier particles from the air stream or projecting these particles against the chamber walls, thereby permitting the particles to cascade to the collecting gates at the bottoms of the respective chambers. In this system, no extensive column or chamber of rising air is required.
  • auxiliary channel to which a portion of the air circulated from the fine separator to the coarse separator is diverted, this channel being provided with a fine-particle or dust filter for removing a fraction of the dust content of the recirculated air, thereby preventing excessive accumulation.
  • FIG. 1 is a front-elevational view of the airclassification apparatus according to the present invention.
  • FIG. 2 is a cross-section taken generally along the line II II of FIG. 1;
  • FIG. 3 is a cross-sectional view taken generally along the line III III of FIG. 1;
  • FIG. 4 is a cross-sectional view taken along the line IV IV of FIG. 1;
  • FIG. 5 is a diagrammatic view similar to FIG. 1, but illustrating another embodiment of the present invention.
  • the apparatus of the present invention comprises a fine-fraction separator l, and a coarse-fraction separator 2 mounted upon respective pedestals 28 and 29 and of generally cylindrical configuration.
  • Each of the separators comprises a bar or blade-cage rotor 3 or 4 having axes A and B, respectively, which are parallel and transversely spaced.
  • each of these rotors there is provided an axial-intake, radial outflow fan 5 or 6 which is driven by respective transmissions 30 and 31.
  • the fan 6 and the respective cage 4 have a support sleeve 32 fixed by cones 33 and 34 to a shaft 35 joumaled in a pair of blocks 36 and 37 outwardly of the housing of the unit.
  • a pulley 38 is provided to constitute part of the transmission system.
  • a belt 39 extends around this pulley and a pulley 40 which is driven by a motor 41 through a mechanical bevel gear transmission 42.
  • a speed control 43 is provided for the motor 41 to regulate the particle size of the fraction collected in the coarse-particle separator.
  • the blower and cage of the fine-fraction separator is similarly mounted and driven.
  • Each of the rotors 3, 5 and 4, 6 is received in a classifying chamber 7 or 8, respectively, with adjacent blower or fan chambers 9 and (see FIGS. 3 and 4).
  • the chamber 7, 9 and 8, 10 are separated from one another by partitions 11, reaching inwardly to positions close to the respective rotors which are provided with circular hubs 13 so that the gaps 12 between the hubs and the confronting partitions form air locks or seals as represented at 12.
  • a supply conduit 14 connects the discharge side (i.e. the periphery of fan chamber 9) of the finefraction separator with the intake side 2 of the coarse fraction separator.
  • the intake side of this separator is formed by a rotationally symmetrical frustoconical portion 16 at the axial end of the coarse-fraction separator 2 remote from the fan compartment 10.
  • the frustoconical portion 16 widens in the direction of the separating chamber 8 until it assumes the diameter thereof.
  • the duct 14 extends tangentially outwardly of the blower compartment 9 of the fineparticle separator and extends tangentially into the frustoconical portion 16 of the coarse-particle separator.
  • a return conduit 15 extends tangentially from the blower chamber 10 of the coarse-particle separator and opens tangentially into the separating chamber 7 of the fine-particle classifier.
  • an inlet 17 for the comminuted material to be classified is provided in the supply conduit 14, there is provided an inlet 17 for the comminuted material to be classified.
  • This inlet is constituted as a lock of substantially conventional construction.
  • a cylindrical seal is flanged at 51 to an upstanding net 52 of the conduit 14 and communicates with the latter while being open at a flange 53 to be connected to a hoper or the like delivering the comminuted material.
  • a semicylindrical closure member 54 is angularly displaceable as represented by arrow C from the position illustrated in which communication with the atmosphere is prevented by the comminuted material can fill the trough formed by member 54, and a position in which the trough opens downwardly to dump the comminuted material but nevertheless prevents communication with the atmosphere.
  • the chambers 7 and 8 are each provided with a respective discharge gate 18 or 19 of the seal type described with respect to the gate 51 54 for discharging the fine and coarse particle fractions respectively.
  • a bypass channel 20 (FIG. 2) in which a dust filter 21 is disposed to recover a portion of the dust from the recirculated air as previously described.
  • the coarse-fraction separator 2 is provided, ahead of the frustoconical housing 16 and within the latter, with a distributing-blade arrangement 22 (with a number of angularly equispaced blades) mounted upon the sleeve 32 for ensuring a uniform distribution of the comminuted material over the entire circumference of chamber 8.
  • a bevel 45 ahead of the rotor 4 co-operates with guide elements 23 to ensure a direction of the comminuted material against the rotor 4 which is between the radial and the axial and, therefore, is generally spiral. In other words, particles are cast against the bars of the rotor in an off-radial direction somewhat transverse to the bars.
  • these guide elements are blades or fans formed on a blade ring mounted in the housing 8.
  • an adjustable flap 24 is provided to control the circulated air stream.
  • the mixture of comminuted material with particles of different sizes ranges is introduced into the inlet 17 and is entrained by the air stream through duct 14 into the housing portion 16 from which it is spread circumferentially and is deflected around the bevel 45 and inwardly against the rotor 4 via the blades 23.
  • the largeparticle fraction is cast outwardly and passes along the wall of the chamber 8 to the discharge duct 25 from which it is removed via the seal gate 19. Because of the relatively small diameter of the rotor 4 and the relatively high air speed, the fine particles continue to be entrained with the air stream and are passed through the duct to enter the chamber 7 tangentially.
  • FIG. 5 there is shown a modified system in which the coarse-fraction separator 102 has its rotor driven in the counterclockwise sense (arrow D) while the rotor of the fine-particle separator 101 is rotated in the clockwise sense (arrow E).
  • the inlet duct 114 connects the fan chamber of the separator 101 with thefrustoconical portion 116 of separator 102 and is provided with an inlet gate 117 as previously described.
  • the duct 1 connects the upper side of the fan chamber of separator 102 to the underside of the separator 101. Consequently, while the system of FIG. 1 provides an overpath for the classifying air, the system of FIG. 5 provides a path having the configuration of a figure 8.
  • An apparatus for the classification of a comminuted material into a plurality of particle-size fractions comprising:
  • each of said separators being provided with:
  • each housing communicating with the respective chamber
  • said intake of said coarse-particle separator comprises a rotationally symmetrical housing coaxial with the respective rotor means, said apparatus further comprising a distributing blade rotatable in said housing for spreading the comminuted material circumferentially about the chamber of said coarse-particle separator.
  • valve means in at least one of said conduits for controlling the air flow along said circuit.
  • bypass means between the outlet of said fineparticle' separator and the intake of said coarse-particle separator and including a filter for removing residual dust from the air delivered to said coarse-particle sepai i i i

Landscapes

  • Combined Means For Separation Of Solids (AREA)
US00125140A 1970-03-18 1971-03-17 Closed circuit multi-stage air classifier Expired - Lifetime US3767045A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2012797A DE2012797C3 (de) 1970-03-18 1970-03-18 Vorrichtung zum Sichten von Schüttgütern

Publications (1)

Publication Number Publication Date
US3767045A true US3767045A (en) 1973-10-23

Family

ID=5765417

Family Applications (1)

Application Number Title Priority Date Filing Date
US00125140A Expired - Lifetime US3767045A (en) 1970-03-18 1971-03-17 Closed circuit multi-stage air classifier

Country Status (7)

Country Link
US (1) US3767045A (fr)
AT (1) AT307007B (fr)
BE (1) BE764428A (fr)
CA (1) CA930696A (fr)
DE (1) DE2012797C3 (fr)
FI (1) FI55128B (fr)
FR (1) FR2084815A5 (fr)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4776950A (en) * 1984-01-14 1988-10-11 Northern Engineering Industries Plc Classifier
EP0534483A2 (fr) * 1991-09-27 1993-03-31 Engma Engineers Beheer Séparateur centrifuge à turbine
US5273163A (en) * 1992-01-23 1993-12-28 Luzenac America, Inc. Centrifugal particle classifier having uniform influx distributor
US5363776A (en) * 1993-08-24 1994-11-15 Sure Alloy Steel Corporation Exhauster inlet venturi
US5938046A (en) * 1995-04-11 1999-08-17 Hosokawa Mikropul Gmbh Air separation grader
US5957299A (en) * 1996-07-08 1999-09-28 Keuschnigg; Josef Separator wheel for an air separator
WO2001042556A1 (fr) * 1999-12-09 2001-06-14 Upm-Kymmene Corporation Procede de tamisage et tamis pour pate a papier
US6276534B1 (en) * 1998-04-03 2001-08-21 Hosokawa Micron Powder Systems Classifier apparatus for particulate matter/powder classifier
US20040144698A1 (en) * 2002-11-07 2004-07-29 Mann & Hummel Gmbh Cyclone separator
US20050132678A1 (en) * 2003-12-19 2005-06-23 Bernard Gemmati Device for heating and/or demisting a vehicle
CN103264017A (zh) * 2013-05-07 2013-08-28 黄世平 一种农作物风净装置

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2018669A (en) * 1931-08-12 1935-10-29 Hermann Charles Edward Air separator
AT156869B (de) * 1936-09-19 1939-09-11 Hermannus Van Ing Tongeren Fliehkraftstaubabscheider.
US2236548A (en) * 1937-11-06 1941-04-01 William B Prouty Material disintegrating and air classifying system
US2269412A (en) * 1940-07-18 1942-01-06 Sturtevant Mill Co Air separator
US2460938A (en) * 1944-08-05 1949-02-08 Johns Manville Method and apparatus for cleaning asbestos
US2633930A (en) * 1950-06-10 1953-04-07 William R Carter Centrifugal air separator for removal and classification of particles
US2973094A (en) * 1958-09-02 1961-02-28 Claude B Schneible Co Separating apparatus and method
US3089595A (en) * 1960-08-06 1963-05-14 Alpine Ag Maschinenfabrik Und Flow apparatus for separating granular particles
US3384238A (en) * 1966-02-17 1968-05-21 Air Sifters Inc Classifying system
GB1200996A (en) * 1968-05-24 1970-08-05 British Rema Mfg Company Ltd Improvements in or relating to air separators for powders and granular materials
US3615009A (en) * 1969-03-03 1971-10-26 Georgia Marble Co Classifying system

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2018669A (en) * 1931-08-12 1935-10-29 Hermann Charles Edward Air separator
AT156869B (de) * 1936-09-19 1939-09-11 Hermannus Van Ing Tongeren Fliehkraftstaubabscheider.
US2236548A (en) * 1937-11-06 1941-04-01 William B Prouty Material disintegrating and air classifying system
US2269412A (en) * 1940-07-18 1942-01-06 Sturtevant Mill Co Air separator
US2460938A (en) * 1944-08-05 1949-02-08 Johns Manville Method and apparatus for cleaning asbestos
US2633930A (en) * 1950-06-10 1953-04-07 William R Carter Centrifugal air separator for removal and classification of particles
US2973094A (en) * 1958-09-02 1961-02-28 Claude B Schneible Co Separating apparatus and method
US3089595A (en) * 1960-08-06 1963-05-14 Alpine Ag Maschinenfabrik Und Flow apparatus for separating granular particles
US3384238A (en) * 1966-02-17 1968-05-21 Air Sifters Inc Classifying system
GB1200996A (en) * 1968-05-24 1970-08-05 British Rema Mfg Company Ltd Improvements in or relating to air separators for powders and granular materials
US3615009A (en) * 1969-03-03 1971-10-26 Georgia Marble Co Classifying system

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4776950A (en) * 1984-01-14 1988-10-11 Northern Engineering Industries Plc Classifier
EP0534483A2 (fr) * 1991-09-27 1993-03-31 Engma Engineers Beheer Séparateur centrifuge à turbine
EP0534483B1 (fr) * 1991-09-27 1998-03-25 Engma Engineers Beheer Séparateur centrifuge à turbine
US5273163A (en) * 1992-01-23 1993-12-28 Luzenac America, Inc. Centrifugal particle classifier having uniform influx distributor
US5363776A (en) * 1993-08-24 1994-11-15 Sure Alloy Steel Corporation Exhauster inlet venturi
US5938046A (en) * 1995-04-11 1999-08-17 Hosokawa Mikropul Gmbh Air separation grader
US5957299A (en) * 1996-07-08 1999-09-28 Keuschnigg; Josef Separator wheel for an air separator
US6276534B1 (en) * 1998-04-03 2001-08-21 Hosokawa Micron Powder Systems Classifier apparatus for particulate matter/powder classifier
WO2001042556A1 (fr) * 1999-12-09 2001-06-14 Upm-Kymmene Corporation Procede de tamisage et tamis pour pate a papier
US20040144698A1 (en) * 2002-11-07 2004-07-29 Mann & Hummel Gmbh Cyclone separator
US7159723B2 (en) * 2002-11-07 2007-01-09 Mann & Hummel Gmbh Cyclone separator
US20050132678A1 (en) * 2003-12-19 2005-06-23 Bernard Gemmati Device for heating and/or demisting a vehicle
US7311745B2 (en) * 2003-12-19 2007-12-25 Eurocopter Device for heating and/or demisting a vehicle
CN103264017A (zh) * 2013-05-07 2013-08-28 黄世平 一种农作物风净装置

Also Published As

Publication number Publication date
DE2012797B2 (de) 1973-04-19
BE764428A (fr) 1971-08-16
AT307007B (de) 1973-05-10
FR2084815A5 (fr) 1971-12-17
DE2012797C3 (de) 1973-11-29
DE2012797A1 (de) 1971-12-09
FI55128B (fi) 1979-02-28
CA930696A (en) 1973-07-24

Similar Documents

Publication Publication Date Title
US3767045A (en) Closed circuit multi-stage air classifier
JPH0258989B2 (fr)
CA1326471C (fr) Appareil de triage par faible courant d'air
JP3294241B2 (ja) 混合廃棄物を処理するための方法、および、この方法を実施する処理プラント
US3925198A (en) Apparatus and method of air classifying municipal solid wastes
RU2364448C2 (ru) Сепаратор сыпучего материала
US3975263A (en) Material separation apparatus and method
US3615008A (en) Centrifugal classifying system
CN109641217A (zh) 操作多体旋风分离机构来分离细粒和超细粒的方法以及多体旋风分离机构
CN111495560A (zh) 一种静态双分级选粉机及半终预粉磨系统
US3490702A (en) Method of accelerating production of portland cement and similar material
SE430659B (sv) Forfarande och apparat for pneumatisk finklassificering
JP5497443B2 (ja) 物質の粒度選択および／または乾燥装置
JP2010510468A5 (fr)
JPS63501347A (ja) 回転分離器
US3524544A (en) Milling plant for sifting damp material
US3384238A (en) Classifying system
RU2629570C1 (ru) Установка для дробления, селективного помола, сушки и сепарации полиминеральных промышленных отходов
US3615009A (en) Classifying system
US3643800A (en) Apparatus for separating solids in a whirling gaseous stream
US10919053B2 (en) Particulate separator
GB987671A (en) Particle classifier and method of classifying particles
JP3089243B1 (ja) セメントクリンカの粉砕装置
US2953307A (en) Synergistic fluid energy reducing and classifying unit
US2915179A (en) Aerodynamic classifier