EP0242458A2 - Verfahren und Apparat zum Extrahieren von Flüssigkeit aus nassem körnigem Gut - Google Patents

Verfahren und Apparat zum Extrahieren von Flüssigkeit aus nassem körnigem Gut Download PDF

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Publication number
EP0242458A2
EP0242458A2 EP86302942A EP86302942A EP0242458A2 EP 0242458 A2 EP0242458 A2 EP 0242458A2 EP 86302942 A EP86302942 A EP 86302942A EP 86302942 A EP86302942 A EP 86302942A EP 0242458 A2 EP0242458 A2 EP 0242458A2
Authority
EP
European Patent Office
Prior art keywords
bowl
shaft
centrifuge
speeds
particulate matter
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.)
Withdrawn
Application number
EP86302942A
Other languages
English (en)
French (fr)
Other versions
EP0242458A3 (de
Inventor
Lloyd Batre Smith
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.)
United Coal Co
Original Assignee
United Coal Co
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 United Coal Co filed Critical United Coal Co
Priority to EP86302942A priority Critical patent/EP0242458A3/de
Priority to AU56517/86A priority patent/AU587448B2/en
Priority to ZA863071A priority patent/ZA863071B/xx
Priority to JP61106552A priority patent/JPS62262719A/ja
Publication of EP0242458A2 publication Critical patent/EP0242458A2/de
Publication of EP0242458A3 publication Critical patent/EP0242458A3/de
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B9/00—Drives specially designed for centrifuges; Arrangement or disposition of transmission gearing; Suspending or balancing rotary bowls
    • B04B9/12—Suspending rotary bowls ; Bearings; Packings for bearings

Definitions

  • the present invention relates to a method and apparatus for centrifugal removal of fluids from wet particulate matter including solid fines, such as ore slurries, industrial wastes, coal, and the like.
  • a centrifuge comprising an envelope, a bowl rotatably mounted within said envelope, a wide mouthed opening at one end of the bowl for introducing material to be dried, a plurality of apertures in said bowl for discharging fluid into said envelope, a base closing the other end of the bowl, a continuous shaft secured to the base at one end of the shaft for mounting the bowl for rotation, means for mounting the shaft for rotation about its axis, and drive means for rotating the shaft and the bowl therewith, the means for mounting the shaft comprising a gimbal-like system mounting the shaft at a second end, to maintain a vertex of precession of the shaft and bowl at said second end in a substantially well defined locus, resilient means, which support the shaft bearings, being located between the vertex and base, and said resilient means being of variable resilience, whereby the natural frequency of the shaft and the bowl may be varied in accordance with the frequency of rotation of the shaft and bowl.
  • Such a construction can dry moist fine particulate to lower moisture levels than has been possible with prior art large scale centrifuges and can do so without causing pollution problems, safety hazards or significant losses of particular material in the fluid extracted therefrom.
  • the centrifuge of the invention is capable of handling unbalanced loads at very high drying speeds, e.g. in excess of 90 metres/sec and of operating at speeds in excess of 22 metres/sec during cutting out of the dried solids.
  • a method for centrifugally removing fluid from wet particulate matter comprising the steps of introducing said wet particulate matter into a batch-type centrifuge having a bowl with an opening at one end for receiving said wet particulate matter, a base at the other end thereof attached to a driven shaft rotatable at various speeds and a filter media liner proximal the inner surface of said bowl; accelerating the rotational speed of said centrifuge to a controlled drying speed to reduce the moisture content of said particulate matter to below a predetermined percentage, by centrifugal extraction of the fluids; decelerating rotational speed of said centrifuge; and removing the particulate matter from said centrifuge at controlled rotational speeds of said centrifuge, supporting said shaft on a gimbal-like unit at the end of the shaft remote from the bowl, to maintain a vertex of precession of said shaft and bowl within a well-defined locus and to constrain said shaft to pivotal motion about said vertex,
  • the method and centrifuge of the invention use a mounting arrangement which takes advantage of the natural physical tendencies of rotating elastic bodies.
  • An elastic body namely, the bowl and shaft of a centrifuge, will vibrate freely at one or more of its natural frequencies if its equilibrium is momentarily disturbed by an external force. If the external force is applied repeatedly the elastic body will vibrate at the frequency of the external excitation.
  • a rotating elastic system will have critical operating speeds at which objectionable vibrations are likely to occur. These speeds correspond to the various natural frequencies of the system. Since imbalances will always exist in the system, there will always be an excitation force with a frequency corresponding to the operating speed. When one of the system's natural frequencies coincides with the rotational frequency of the system, resonance results with maximum vibration of the system.
  • the natural frequencies and consequently the critical speeds are not merely a property of the rotating shaft alone, rather they are also affected by the bearings, the supports, and the foundation; thus variation in these contributing factors will result in a variation of the natural frequencies and the critical speed.
  • the invention utilizes support members of variable resilience to alter the natural radial frequency of the system.
  • a batch-type centrifuge by design rotates at a variable speed which ranges from a relatively low cut-out speed for removal of the dried fines, a moderately higher loading speed and a very high drying speed. Consequently, the rotational speed of the centrifuge will pass through a critical speed or be required to operate for a time at a critical speed corresponding to the natural radial frequency.
  • the resilience of support members it is possible to shift the natural radial frequency so that the transition across the critical speed is almost instantaneous.
  • the radial natural frequency can be shifted so that the centrifuge may operate for a period of time, such as at cut-out, at a speed corresponding to a frequency below the natural radial frequency.
  • the operating speed is not the only factor contributing to the amplitude of the vibration at resonance. Another very important factor is the damping of the system. Damping, however, is both friend and foe to a system which must operate over a wide range of speeds. At resonance, it is desirable for the actual damping to approach the critical damping of the system, thereby taking energy from the shaft and decreasing the amplitude of the vibration of the system. At the much higher drying speeds, it is desirable for actual damping to be minimal in order efficiently to utilize the energy of the system in rotating the shaft and bowl. Therefore, preferably a variable rate energy absorption means is used as a damper to stabilize the bowl against excessive radial excursions during cut-out at speeds near resonance, and to allow the system to vibrate freely at the higher drying speeds.
  • the centrifuge of the invention utilizes an overhung bowl, in order accurately to control the radial vibration of the system, there must be a means of maintaining the vertex of the system within a well defined locus. This is accomplished using at the end of the shaft opposite the bowl attachment, a gimbal-like system and the utilization of a drive means inputting rotational force proximal the vertex minimizes the radial vibration at the vertex and the external excitation to the rotating elements and isolates the support structure from receiving radial vibration transmitted at the vertex of the system.
  • the apparatus shown in Figure 1 includes a base frame member 11 having an upper housing 12 which carries an envelope 13 therewithin which encases a bowl 14.
  • the envelope 13 is used to confine and remove fluids extracted from the fines within the bowl 14 as is well known in the art.
  • the bowl 14 has a base support 16 affixed conventionally to a continuous rotatable shaft 17 which rotates within longitudinally spaced bearings 18 and 20.
  • the end of the shaft 17 opposite the bowl 14 is mounted for rotation on a gimbal-like system 19, which is affixed to and supports the shaft 17 whereby there is maintained a vertex of precession 21 of the shaft 17 and bowl 14.
  • a resilient support structure 22 which has two principal types of components, with one being in the form of air bags 23 and the other in the form of semi-rigid supports 24.
  • the air bags 23 and semi-rigid supports 24 are symetrically positioned about a bearing sleeve 26 containing the bearings 18 and the shaft 17 so that the structure 22 supports the bearings 18 at an area near the bowl 14.
  • the semi-rigid supports 24 are placed intermediate each pair of air bags 23, but they could be integrated within the air bags 23, if the latter provide the sole support to the bearing sleeve 26 when they are fully inflated.
  • the supports 24 may also be mounted on fluid actuated cylinders 25, as shown in Figure 3a.
  • the air bags are mounted on the base frame 11 by connecting members 27 extending radially inwardly from a mounting collar 28 affixed to the base frame 11.
  • a source of compressed air not shown, is used individually to control the inflation of each air bag 23.
  • the semi-rigid supports 24 are also mounted on the collar 28 and extend radially inwardly therefrom, as shown in Figure 3.
  • the supports 24 include rubber pads 29 on the inwardly facing ends thereof, with the pads 29 being separated from the sleeve 26 when the air bags 23 are inflated and with the lower pads 29 abutting the sleeve 26 upon deflation of some or all of the air bags 23.
  • shock absorbers 31 and 32 are mounted between the sleeve 26 and the collar 28 at angularly spaced locations relative to each other.
  • the shock absorbers 31 and 32 are used to dampen the system from excessive radial motion such as may occur at resonance. It is preferable that the energy absorption capabilities of these shock absorbers be variable so that they may stabilize the bowl 14 at cut-out speeds for the removal of the dried particulate and yet absorb minimal energy at the drying speeds; however standard industrial shock absorbers may be used.
  • Figure 2 shows one such variable shock absorber 31, which uses a flat bar 33 operatively connected to the sleeve 26 and extending into a housing 34 within which a hydraulically actuated clamp 36 is positioned to open and close about the bar 33.
  • the pressure exerted on the bar 33 is determined by the hydraulic pressure provided to a hydraulic line 37 and cylinder 38 from an external hydraulic source, not shown.
  • the gimbal-like system 19 includes a yoke 41 having transverse pins 42 and 43 pivotally secured to the base frame 11.
  • a vertical pin 44 extends downwardly from the yoke 41 and supports one end of a truss 46 which is connected at its opposite end to the sleeve 26 to support the shaft 17, which is restrained from axial movement within the sleeve 26.
  • This gimbal-like system 19 allows the bowl 14 and shaft 17 to be displaced vertically and horizontally within the restriction placed on the shaft 17 by the resilient support structure 22 while maintaining the vertex 21 of precession of the shaft 17 at a substantially well defined locus.
  • a variable speed drive 47 such as a variable frequency alternating current drive, is coupled to the shaft 17 by at least one drive belt 48 which transfers rotational force to the shaft 17 at a belt receiving groove 49 located at the locus of the vertex 21.
  • the drive means may be directly coupled to the shaft 17 with a flexible coupling 63 such as a gear-type flexible coupling which is well known in the art.
  • Alternative drive means such as variable speed direct current drives or hydraulic variable speed drives may also be used.
  • the use of the flexible coupling 63 requires the use of a gimbal fork 64 and gimbal ring 66 rather than the aforementioned yoke 41 and truss 46, but they operate in the same way to isolate the rotating elements from the remainder of the centrifuge and to maintain the vertex 21 in a well defined locus.
  • the use of the gimbal-like system 19 resolves the three-dimensional vibration problem into a two-dimensional problem at the mounting collar 28 while isolating the base frame 11 from receiving excessive vibration which would result if a fixed bearing support system were used to support the shaft 17.
  • This allows for the use of a very high rate of rotation which places very high centrifugal stresses on the loaded bowl 14. Therefore the bowl construction merits discussion in that the preferable construction of bowl 14 utilizes a composite material, such as a carbon fibre reinforced epoxy, due to its combined strength, stiffness, and durability.
  • Such composite materials have a very high strength-to-weight ratio and thus give marked advantages over other materials.
  • an expandable metallic bowl as shown in Figure 5, which utilizes an expandable shell 51 attached to a base support 52 by a plurality of radially extending pins 53 which allow the shell to expand under stress as is well known in the art and exemplified in U.S. Patent No. 3,282,498.
  • the bowl 14 is substantially circular in cross-section and has a plurality of generally outwardly directed angularly spaced apertures 54 which allow the extracted fluids to exit the bowl into the envelope 13 from whence the fluids are conventionally removed.
  • an imperforate shell 51 with substantially axially directed ports 54 ⁇ at the ends of the bowl are preferred, while in the composite bowl construction radially directed ports 54 are preferred.
  • ring seals 56 are carried between the bowl 14 and the housing 12.
  • the bowl 14 has a radially and inwardly extending annular lip 57 of a radial dimension substantially equal to the thickness of the particulate material deposited in the bowl adjacent the lip 57, which carries one set of ring seals 56 and defines a generally unobstructed opening 58 into the bowl 14.
  • This opening 58 allows both ingress and egress for the particulate matter which may be introduced and removed by any number of conveyors, sprayers, scrapers, blades and the like as may be convenient with the particulate matter being dried and as is indicated schematically at 59 in Figure 2.
  • the bowl contains an appropriate mesh size filter media 61, mounted on a filter media support 62 which allows extracted fluid to exit the bowl 14.
  • the filter media 61 and filter media support 62 may be peaked near the centre of the shell 51 and flare outwardly toward each end to bias the flow of extracted fluids toward the axially directed ports 54 ⁇ under enhanced radial force.
  • the wet particulate matter is introduced into the bowl 14 while it is rotating and is cut-out or removed from the bowl 14 while it is rotating. Between the time the particulate is introduced and the time the dried particles are removed, the bowl is accelerated to the drying speed.
  • the centrifuge can operate at higher speeds than conventional batch centrifuges with the outer surface having a linear speed during cut out in excess of 22.8 metres/sec, during loading in excess of 55.8 metres/sec and during drying in excess of 91 metres/sec.
  • the bowl 14 it will be appreciated that removing the particulate from the bowl at this high cut-out speed requires the bowl 14 to be relatively stable.
  • the natural radial frequency of the system when supported on the air bags 23 is about 700 to 800 cycles per minute, 27.4 to 31.5 metres/sec outer surface speed, when a 0.75 metre outside diameter bowl is being used.
  • the cut-out speeds will include a rotational speed corresponding to the natural radial frequency and resonance will result.
  • Figures 6a and 6b derived from Fan Engineering, edited by Robert Jorgenson and published by Buffalo Forge Co, illustrates the problem associated with rotating an elastic system with an unbalanced load at resonance.
  • the rotational frequency f for a 0.75 m outside diameter bowl for example, is usually 2400 rpm or greater and the shaft is supported on the air bags 23, thus the natural radial frequency fn is 700-800 cycles per minute, so that the frequency ratio f/fn is approximately 3.0 or greater.
  • the amplitude of the non-dimensional response Mx/me for the forced vibration of a system resulting from rotating imbalance is approximately 1.0.
  • the total vibrating mass M includes the rotating mass m which has an eccentricity of e, the system amplitude is x and the phase angle or lag of the response behind the imbalance is ⁇ .
  • the curved lines on the Figures correspond to the response and phase angles at various ratios C between the actual damping on the system c, and the critical damping cc of the system.
  • the response will be approximately equal in amplitude to the imbalance and lag behind the imbalance by nearly 180°; thus the system will be self-balancing at the drying speed, particularly if the system has a damping ratio which is very small, such as 0.05. Therefore, at drying speeds it is desirable that the shock absorbers 31 influence the system minimally.
  • one of the air bags 23a is deflated as the rotational speed of the bowl 14 is reduced from the drying speed, and the bearing is then supported by the semi-rigid supports 24.
  • supports 24 are moved into engagement with the bearing by a fluid pressure operated cylinder 25 as shown in Figure 3A.
  • the support structure 22 is thereby changed to a less resilient or stiffer support which increases the natural radial frequency fn of the system and increases the hysteresis of the supports. That is to say, the rubber pads 29 and support 24 remove energy from the system.
  • the bowl 14 is thus stabilized against excessive radial movement and the cutting out of the dried particulate can proceed safely.
  • the dried particulate removed is not dusty but, rather, has a consistency somewhat like table salt; therefore it is not as subject to the same transportation losses due to dusting as thermally dried particulate would be.
  • the bowl's rotational speed is increased. For example, with a 0.75 m outside diameter bowl the speed is increased to above 1400 rpm and wet particulate is introduced. As the speed increases the air bag 23a is reinflated and thus the natural radial frequency fn is decreased, such that the transition across the resonance speed is again quite brief, thereby causing no problems with excessive radial excursions. The bowl is then accelerated to drying speeds, usually in excess of 2400 rpm for a 0.75 m outside diameter bowl. The entire cycle takes as little as 90 seconds. It will be noted that the resilient support 22 incorporates a built-in safety feature due to its double support system. In the event of a failure of an air bag 23, the bearing sleeve 26, bearing 18, and shaft 17 will be engaged by the lower semi-rigid supports 24 and the centrifuge may be safely stopped.
  • the centrifuge of the invention can use lighter-weight materials for the shaft due to the reduction of vibratory stress, can process particulate matter more rapidly and economically; is less subject to fatigue or wear due to excessive vibration and is simpler and cheaper to construct and operate than are prior centrifuges.

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  • Centrifugal Separators (AREA)
  • Filtration Of Liquid (AREA)
  • Solid Fuels And Fuel-Associated Substances (AREA)
EP86302942A 1986-04-18 1986-04-18 Verfahren und Apparat zum Extrahieren von Flüssigkeit aus nassem körnigem Gut Withdrawn EP0242458A3 (de)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP86302942A EP0242458A3 (de) 1986-04-18 1986-04-18 Verfahren und Apparat zum Extrahieren von Flüssigkeit aus nassem körnigem Gut
AU56517/86A AU587448B2 (en) 1986-04-18 1986-04-23 Method and apparatus for extracting fluid from wet particulate matter
ZA863071A ZA863071B (en) 1986-04-18 1986-04-24 Method and apparatus for extracting fluid from wet particulate matter
JP61106552A JPS62262719A (ja) 1986-04-18 1986-05-09 湿潤物質から流体を遠心分離除去するための方法および装置

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP86302942A EP0242458A3 (de) 1986-04-18 1986-04-18 Verfahren und Apparat zum Extrahieren von Flüssigkeit aus nassem körnigem Gut

Publications (2)

Publication Number Publication Date
EP0242458A2 true EP0242458A2 (de) 1987-10-28
EP0242458A3 EP0242458A3 (de) 1988-06-15

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ID=8195974

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86302942A Withdrawn EP0242458A3 (de) 1986-04-18 1986-04-18 Verfahren und Apparat zum Extrahieren von Flüssigkeit aus nassem körnigem Gut

Country Status (4)

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EP (1) EP0242458A3 (de)
JP (1) JPS62262719A (de)
AU (1) AU587448B2 (de)
ZA (1) ZA863071B (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016046704A1 (en) * 2014-09-25 2016-03-31 Flsmidth A/S Centrifuge seals and sealing arrangements and centrifuges containing the same
CN111873795A (zh) * 2020-07-24 2020-11-03 中国重汽集团济南动力有限公司 一种商用车传动轴用气囊式中间支承装置、装配方法及使用方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7738347B1 (ja) * 2024-05-13 2025-09-12 株式会社流機エンジニアリング ろ過システム

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2155919A (en) * 1937-08-04 1939-04-25 Timken Roller Bearing Co Shaft bearing mounting
BE430723A (de) * 1937-10-21
DE1051202B (de) * 1955-11-05 1959-02-19 Hermann Hullen Haengezentrifuge mit starr angebautem, kardanisch aufgehaengtem Antriebmotor
GB978427A (en) * 1960-01-19 1964-12-23 Hoover Ltd Improvements relating to spin drying machines
US3282498A (en) * 1963-06-10 1966-11-01 Lloyd B Smith Construction for high gravity centrifuges and the like
DE1904774B2 (de) * 1969-01-31 1971-12-23 Braunschweigische Maschinenbauanstalt, 3300 Braunschweig Zentrifuge insbesondere fuer die zuckergewinnung
US3822498A (en) * 1973-03-02 1974-07-09 D Butler Aerator for a fish live well
DE3174654D1 (en) * 1981-12-24 1986-06-19 Schenck Ag Carl Bearing for a balancing machine for balancing elastic rotors
US4640770A (en) * 1985-04-03 1987-02-03 United Coal Company Apparatus for extracting water from solid fines or the like

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016046704A1 (en) * 2014-09-25 2016-03-31 Flsmidth A/S Centrifuge seals and sealing arrangements and centrifuges containing the same
US10300498B2 (en) 2014-09-25 2019-05-28 Flsmidth A/S Centrifuge seals and sealing arrangements and centrifuges containing the same
AU2015323418B2 (en) * 2014-09-25 2019-08-01 Flsmidth A/S Centrifuge seals and sealing arrangements and centrifuges containing the same
CN111873795A (zh) * 2020-07-24 2020-11-03 中国重汽集团济南动力有限公司 一种商用车传动轴用气囊式中间支承装置、装配方法及使用方法

Also Published As

Publication number Publication date
AU587448B2 (en) 1989-08-17
AU5651786A (en) 1987-10-29
JPS62262719A (ja) 1987-11-14
ZA863071B (en) 1986-10-23
EP0242458A3 (de) 1988-06-15

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