EP0271279A2 - Centrifugeuse - Google Patents

Centrifugeuse Download PDF

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Publication number
EP0271279A2
EP0271279A2 EP87310616A EP87310616A EP0271279A2 EP 0271279 A2 EP0271279 A2 EP 0271279A2 EP 87310616 A EP87310616 A EP 87310616A EP 87310616 A EP87310616 A EP 87310616A EP 0271279 A2 EP0271279 A2 EP 0271279A2
Authority
EP
European Patent Office
Prior art keywords
ring
gimbal
bowl
mounting
neutralizer
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Withdrawn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
EP87310616A
Other languages
German (de)
English (en)
Other versions
EP0271279A3 (fr
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
Publication of EP0271279A2 publication Critical patent/EP0271279A2/fr
Publication of EP0271279A3 publication Critical patent/EP0271279A3/fr
Withdrawn legal-status Critical Current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
    • B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
    • 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
    • B04B9/14—Balancing rotary bowls ; Schrappers

Definitions

  • the present invention relates to centrifuges of the type wherein high speeds are attained through the use of a light-weight composite bowl mounted on a gimbal-mounted shaft.
  • US-A-4640770 and 4639320 disclose a gimbal-mounted centrifuge to transit the critical speeds of rotation of a centrifuge with little transfer of energy to the gimbal-like structure in which the rotor is mounted, and provide the structure necessary successfully to operate a high speed overhung bowl centrifuge.
  • the rotating elements are dynamically balanced such that at high speed operation, above the critical speeds, the elements tend to rotate about their geometric longitudinal axis and develop a moment of inertia of WK2, where W is the mass (although weight is used in some calculations for simplicity) and K is the radius of gyration of the elements about the axis.
  • W the mass (although weight is used in some calculations for simplicity)
  • K the radius of gyration of the elements about the axis.
  • a centrifuge for extracting fluids from wet particulate material
  • said centrifuge comprises a rotor system including an overhung composite bowl having a mouth at one end thereof and a base at the other end, a filter media liner proximal the inner surface of the bowl, a plurality of outlet ports through said bowl for the outward discharge of said fluids, a continuous shaft fixed to said base at one end a gimbal-like mounting at a second end of said shaft for driving it in rotation, bearings located intermediate said gimbal-like mounting and said bowl, with said shaft and said bowl being resiliently supported thereon and a neutralizer ring affixed to said bowl about the mouth thereof and being dynamically balanced, with said ring having a weight, W, and a radius of gyration, K ng , about said gimbal-like mounting, such that said neutralizer ring neutralizes the effects of imbalance in a predetermined weight of particulate material and causes the geometric axis and the
  • Such a construction enables one to dynamically balance a gimballed centrifuge having a known capacity while the centrifuge is rotating at speeds above the critical or resonant speeds, enabling the centrifuge to be in balance at its drying speeds.
  • the gimballed centrifuge of the invention can have improved longevity and reliability due to the reduced reactive stress placed on the gimbal and it is possible to use a light-weight composite bowl in a high speed centrifuge.
  • the centrifuge of US-A-4640770 and 4639320 utilize a gimbal-like drive connection to power a shaft which turns in a bearing supported on a plurality of bearings of variable resiliency.
  • An overhung bowl is connected to the shaft at a hub such that the shaft and bowl are free to undergo limited radial displacement without inducing severe bending stresses on either the bowl or shaft.
  • the combined mass of the bowl and load exert an undesirable centrifugal force which induces a radial diplacement at a velocity sufficient to generate a reactive force on the gimbal of an undesirable magnitude. This is particularly true when the bowl is made of a light-weight composite material.
  • the construction of the invention utilizes the propensity of the system to induce reactive forces on the gimbal responsive to the unbalanced condition, as if the unbalanced system were a mass W t located at a radius of gyration K t relative to the gimbal.
  • a neutralizer ring which will minimize the reactive force on the gimbal by causing the geometric axis of the system and the instantaneous dynamic axis of the system to be aligned at the gimbal.
  • the moment of inertia (WK2) of each component relative to the gimbal is determined and summed to yield the total (WK2) t from which the system radius of gyration K t relative to the gimbal is determined.
  • WK2 moment of inertia
  • the gyroscopic effect at the radius of gyration K t can be calculated and the first moment of each component relative to a point at K t can be calculated. The sum of the first moments and the gyro effect are used to determine the resultant force on the gimbal.
  • the neutralizing ring is located and sized such that the combined torque from the mass and gyro effect of the neutralizer ring about the point K t must be equal and opposite in direction to the torque induced by all the other masses in the system. In determining the torque induced by the other masses, it is apparent that the neutralizer ring must be located outwardly beyond K t .
  • the neutralizer ring must have a diameter acceptable to the size of the bowl, which limits the possible radius of gyration K na of the neutralizer ring relative to the axis.
  • the solution to the problem is the optimization of three variables, the weight of the neutralizer ring (W n ), the radius of gyration of the neutralizer ring relative to the gimbal (K ng ), and the radius of gyration of the neutralizer ring relative to the axis of the system (K na ), and the deployment of the neutralizer ring in accordance therewith.
  • a rotor system 10 of a centrifuge such as described in US-A-4640770 which is incorporated herein by reference, is shown schematically with much of the support structure eliminated for clarity.
  • the rotor system 10 has a geometric or rest axis indicated at A about which it should rotate if perfectly balanced. Input power for rotation is provided via gimbal-like connection 11.
  • a drive shaft 12 rotates in a bearing sleeve 13 which is supported on a suspension bearing 19 of variable resiliency as described in US-A-4640770.
  • a hub 14 affixed to the shaft 12 supports an overhung bowl 16, made of a light-weight composite material, the bowl having a mouth 15 at the end remote from hub 14.
  • the rotor system 10 is depicted as having undergone a deflection at an exaggerated angle such that the instantaneous dynamic axis is indicated at D. It is to be understood that the Figure is an instananeous representation of the rotor system 10 which in reality would describe an orbit about the geometric axis A. It is also to be understood that the rotor system 10 can be modeled by a set of masses and appropriate radii of gyration.
  • the shaft 12 may be considered to have a mass M s , a radius of gyration about the gimbal denoted by K srg and a radius of gyration about the geometric axis A, K sa ;
  • the hub has a mass M h , and radius of gyration of K hg and K ha ;
  • the bowl and load have a combined mass M b , radius of gyration K bg and K ba ;
  • the bearing has a mass M r and a radius of gyration K rg about the gimbal.
  • the radii of gyration relative to the geometric axis are not designated in the Figure; however it is to be understood that they are physical dimensions which can readily be determined from the geometry of the centrifuge.
  • the present invention may be used with any centrifuge having an overhung bowl and gimbal-mounted rotor system, it is particularly useful with a light weight, high strength composite bowl which has a mass less than the mass of particulate 17 centrifuged therein.
  • a system is described and referred to throughout the remainder of the specification.
  • the particulate 17 and bowl have a combined weight of 499 kg
  • the hub 14 has a weight of 129.36 kg
  • the shaft 12 has a weight of 72.48 kg
  • the weight of the bearing 13 is 108.72 kg.
  • the total WK2 of the system with respect to the gimbal can be determined by summing the WK2 of the components as shown in Table 1.
  • the radius of gyration of the system relative to the gimbal, K t may be calculated by This radius of gyration K t is taken to be the point in the system at or about which all of the reactive forces act including the gyroscopic force P induced by the deflection of the unbalanced load.
  • the sum of the first moments of the components about a point C located at K t and the gyroscopic effect must be determined to determine the force acting on the gimbal due to the unbalanced condition.
  • These first moments are taken about point C at K t such that clockwise moments are considered positive and counter clockwise negative.
  • the number of gravities for each item is calculated from the relation a.R t N2 where a is a constant.
  • a is a constant.
  • each balanced component exerts its force toward the axis of rotation whereas the unbalanced load exerts a force away from the axis consequently.
  • Table 2 shows the summation of the moments about K t . Additionally, the gyro precessional torque P kt of the rotating components is determined and summed with the first moments using the expression where V is the linear velocity of a point on the axis at K t from the gimbal and W is the weight of the rotating parts and K r is the radius of gyration of the rotor system relative to the axis thereof.
  • the resultant gyroscopic precessional torque is directed toward the geometric axis at K t and has a magnitude of -539 kg.m, thus the sum of the first moments and precessional torque at K t is 1039.12 kg.m and the force on the gimbal as a result is which is sufficient to damage the centrifuge.
  • a neutralizer ring 18 is mounted about the mouth 15 of the bowl 16 and is affixed thereto, for example by means of nuts and bolts, so that it does not move relative to the bowl. In the described example, this will locate the ring at a radius of gyration K ng about the gimbal of 1.99 m.
  • the addition of the neutralizer ring 18 changes the WK2 of the entire system, so each of the preceding calculations must be performed to optimize the mass.
  • the radius of gyration of the neutralizer ring 18 about the gimbal is constrained by the displacement of the bowl mouth 15 from the gimbal and the radius of gyration of the neutralizer ring 18 about the axis is constrained by the size of the bowl mouth.
  • the diameter of the ring 18 thus has a lower limit defined by the size of the bowl mouth.
  • the thickness and outer diameter of the ring 18 are dimensions which can be varied to locate the centre of mass at the desired K na and K ng . Therefore the most easily changed variable is the mass of the ring, although both K na and K ng can be varied by varying the geometry of the bowl.
  • the mass of the ring 18 is varied by the selection of the ring material, which may be any material which can be formed into a solid ring and which will withstand the forces generated by the centrifuge, and by the physical dimensions selected for the ring.
  • Table 3 provides the relationship between the mass of the neutralizer ring 18 and the force exerted on the gimbal when K ng is taken to be 1.99 m.
  • the neutralizer ring may be constructed which all effectively minimize the reactive force on the gimbal of the system and thus greatly enhance the useful life of the gimbal mounted centrifuge.

Landscapes

  • Centrifugal Separators (AREA)
EP87310616A 1986-12-12 1987-12-02 Centrifugeuse Withdrawn EP0271279A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US94129086A 1986-12-12 1986-12-12
US941290 1986-12-12

Publications (2)

Publication Number Publication Date
EP0271279A2 true EP0271279A2 (fr) 1988-06-15
EP0271279A3 EP0271279A3 (fr) 1989-07-12

Family

ID=25476244

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87310616A Withdrawn EP0271279A3 (fr) 1986-12-12 1987-12-02 Centrifugeuse

Country Status (5)

Country Link
EP (1) EP0271279A3 (fr)
JP (1) JPS63197561A (fr)
KR (1) KR880007131A (fr)
AU (1) AU8215887A (fr)
ZA (1) ZA879283B (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE141240C (fr) *
DE34153C (de) * E. ROTHE in Breitenau bei Oederan Veränderte Anordnung der durch Patent Nr. 23593 geschützten Ringe an Centrifugen
US3362198A (en) * 1966-08-04 1968-01-09 Gen Electric Washing machine balancing means
US3683647A (en) * 1970-10-09 1972-08-15 Chester L Coshow Washing machine
DE2746989B2 (fr) * 1976-10-20 1980-11-06 Hitachi, Ltd., Tokio

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE141240C (fr) *
DE34153C (de) * E. ROTHE in Breitenau bei Oederan Veränderte Anordnung der durch Patent Nr. 23593 geschützten Ringe an Centrifugen
US3362198A (en) * 1966-08-04 1968-01-09 Gen Electric Washing machine balancing means
US3683647A (en) * 1970-10-09 1972-08-15 Chester L Coshow Washing machine
DE2746989B2 (fr) * 1976-10-20 1980-11-06 Hitachi, Ltd., Tokio

Also Published As

Publication number Publication date
EP0271279A3 (fr) 1989-07-12
ZA879283B (en) 1988-09-28
JPS63197561A (ja) 1988-08-16
KR880007131A (ko) 1988-08-26
AU8215887A (en) 1988-06-16

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