EP0783375A1 - Separateur d'elimination des impuretes d'un fluide - Google Patents

Separateur d'elimination des impuretes d'un fluide

Info

Publication number
EP0783375A1
EP0783375A1 EP94929702A EP94929702A EP0783375A1 EP 0783375 A1 EP0783375 A1 EP 0783375A1 EP 94929702 A EP94929702 A EP 94929702A EP 94929702 A EP94929702 A EP 94929702A EP 0783375 A1 EP0783375 A1 EP 0783375A1
Authority
EP
European Patent Office
Prior art keywords
tank
fluid
outlet
wall
screen means
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Withdrawn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
EP94929702A
Other languages
German (de)
English (en)
Inventor
Lennart Gustavsson
Theodor Mollatt
Kenneth Persson
Christen GRÖNVOLD-HANSEN
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.)
Metso Fiber Karlstad AB
Original Assignee
Kvaerner Pulping AB
Kvaerner Pulping Technologies AB
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 Kvaerner Pulping AB, Kvaerner Pulping Technologies AB filed Critical Kvaerner Pulping AB
Publication of EP0783375A1 publication Critical patent/EP0783375A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
    • B04C5/00—Apparatus in which the axial direction of the vortex is reversed
    • B04C5/08—Vortex chamber constructions
    • B04C5/10—Vortex chamber constructions with perforated walls
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
    • B04C5/00—Apparatus in which the axial direction of the vortex is reversed
    • B04C5/08—Vortex chamber constructions
    • B04C5/103—Bodies or members, e.g. bulkheads, guides, in the vortex chamber
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
    • B04C5/00—Apparatus in which the axial direction of the vortex is reversed
    • B04C5/12—Construction of the overflow ducting, e.g. diffusing or spiral exits
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
    • B04C5/00—Apparatus in which the axial direction of the vortex is reversed
    • B04C5/14—Construction of the underflow ducting; Apex constructions; Discharge arrangements ; discharge through sidewall provided with a few slits or perforations
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
    • D21D5/18—Purification of the pulp suspension by mechanical means; Apparatus therefor with the aid of centrifugal force
    • D21D5/24—Purification of the pulp suspension by mechanical means; Apparatus therefor with the aid of centrifugal force in cyclones

Definitions

  • the invention relates to an apparatus for removing impurities from a fluid, comprising a tank having a sidewall with a substantially circular cross-section, an inlet arranged in said sidewall for introducing said fluid into said tank in a manner so as to cause said fluid to circulate in said tank, and an outlet arranged for conducting fluid out of said tank.
  • the invention relates to a hydrocyclone used for removing solid particles such as sand, from an inlet fluid such as the digesting, washing or bleaching liquors used in the production of cellulosic pulp.
  • a device of the aforementioned type is known for example from US-A-4 280 902.
  • the fluid containing the solid impurities in particular sand
  • US-A-4 280 902. the fluid containing the solid impurities (in particular sand) is pumped into the separation tank through a substantially tangential inlet with respect to said tank, thus causing the fluid to circulate or whirl around the interior of the tank.
  • the solid particles in the fluid tend towards the sidewall of the tank due to the centrifugal force.
  • the particles sink downwards to the lower part of the tank and into a suitably arranged sand trap, which can be periodically emptied as required.
  • a main outlet for the relatively purified fluid is arranged at the opposite end of the tank to the sand trap, i.e. the upper wall. Since the sand or other heavier impurities will be travelling outwardly and downwardly, the fluid which is at the upper part of the tank will be relatively free of solid particles and will exit through the aforementioned outlet.
  • the outlet fluid from the separation tank is fed to the chip chute of a pulping plant, said chip chute being arranged between a relatively low pressure (e.g. 2 bar) device, such as a steaming vessel for wood chips, and a high pressure feeder (HP-feeder) responsible for pumping chips to an impregnation vessel (or the digester, if a one-vessel system is used) , said chip chute carrying moisturised chips.
  • a relatively low pressure (e.g. 2 bar) device such as a steaming vessel for wood chips
  • HP-feeder high pressure feeder
  • the fluid, including fluid coming from the chip chute (and also fluid from the impregnation vessel) , which is not transported with the chips from the high pressure feeder is then reintroduced into the separation device for further separation (since it now contains further impurities which were present with the chips coming from the steaming vessel) .
  • a buffer tank In order to be able to provide for storage of excess fluid (e.g. wood moisture and HP-feeder lubricating liquid in addition to the normal liquors) leaving the separation tank, i.e. in the case where the flow is greater than needed, a buffer tank is required. Fluid is fed to the buffer tank from the separation tank, in the prior art devices, by a branch connection from the main outlet or by a branch connection downstream thereof. Some of the buffer tank fluid is used downstream of the HP- feeder e.g. in the impregnation vessel. Accordingly it must be pumped from the buffer tank to a very high level/pressure which has to be formed by means of a pump having extremely high head (e.g. having a pump pressure, p pump .
  • a pump having extremely high head e.g. having a pump pressure, p pump .
  • An object of the invention is thus to reduce cost by providing an apparatus which removes impurities from a fluid outlet of the separation tank and thus obviates the need for any extra in-line drainer or other additional external separator unit for the buffer tank fluid.
  • Fig.l depicts a view of an apparatus made in accordance with the invention.
  • Fig.2 shows a plan view of the device of Fig.l.
  • FIG.l depicts a view of one embodiment of the separation apparatus in accordance with the present invention.
  • a metal tank 10 comprising four main parts, namely a top section 27, a substantially circularly-cylindrical sidewall section 12, a conical sidewall section 21 and a sand trap section 23 are attached to each other to form an enclosed space.
  • An inlet orifice 11 is provided in the sidewall section 12 at approximately the mid-portion thereof and has attached thereto, or integral therewith, an inlet pipe 25, through which is fed the fluid containing dense particles to be removed, for example emanating from an outlet of the high pressure feeder in a pulping plant.
  • the fluid is fed by suitable means into the tank 10 so that it enters the tank with a force causing the fluid to circulate around the tank. In the steady state the tank will of course be full and the body of fluid will all be rotating.
  • the inlet pipe 25 is so arranged, in its preferred form, to introduce fluid into the tank in a substantially tangential manner as shown. The direction of rotation of the fluid in the tank will therefore be as shown by the arrow in Fig. 2 and the corresponding arrow in Fig.l.
  • a vertical stagnation prevention device 22 may also be present in the sand trap section and may correspond to the sand trap in the aforementioned US-A-4 280 902.
  • the tank thus operates as a hydrocyclone separator.
  • the fluid at the upper part of the tank will exit via the main outlet 17 and the outlet 13 to a buffer tank (not shown) by way of outlet pipe 26 which is arranged substantially tangentially with respect to the tank in a manner similar to the inlet pipe, although in the opposite direction with respect to fluid circulation.
  • outlet pipe 26 which is arranged substantially tangentially with respect to the tank in a manner similar to the inlet pipe, although in the opposite direction with respect to fluid circulation.
  • Normally the outlet through the main outlet 17 is much greater than that through the outlet 13 to the buffer tank.
  • the circulating fluid at the upper part of the tank may still contain some particles (especially less dense particles, such as wood chips) which will exit via outlet 13, requiring their subsequent removal external to the tank.
  • a wall/screen means 15 is provided to prevent particulate material exiting the tank via the outlet 13.
  • the wall/screen means in the preferred embodiment comprises a plate-like element which is attached to the sidewall at location 16 in such a way that no circulating fluid, or at least no substantial part of it, may pass between it and the sidewall at the level of the outlet 13.
  • a suitable means of attaching the wall/screen means 15 would be by welding for example.
  • the wall/screen means 15 extends from location 16 around preferably about one quarter of the periphery of the tank and thus extends upstream and downstream of the outlet 13 with respect to the fluid circulation direction.
  • the wall/screen means is preferably so arranged that a gap is formed between it and the tank sidewall 12, being substantially totally open at the downstream end thereof and separated from the sidewall by a distance x 2 .
  • suitable attachment means between the wall/screen means 15 and the tank at locations other than just location 16 will be provided.
  • the wall/screen means 15 is shown as having an ovally arcuate shape in plan view, extending in the direction of fluid circulation at an increasing distance x,, x 2 from the sidewall 12. In this way, the fluid circulation path around the tank undergoes very little interruption upon meeting the wall/screen means 15 since its direction is modified slowly and smoothly.
  • the invention is however clearly not limited to such an embodiment and the plate could for example be formed by a short leading section at location 16 or thereabouts and then a plate having a circularly arcuate shape which is at a constant distance from the sidewall.
  • the wall/screen means need not extend as far as shown with respect to the outlet if the circulation velocity of the fluid is sufficient for efficient operation, or the wall/screen means may extend further if deemed appropriate.
  • the optimal design of the wall/screen means 15 would differ depending on the circumstances, e.g. fluid velocity etc. Accordingly in some separators a non-penetrable wall is preferred whereas in others a partly or totally penetrable (e.g. with punched holes) wall/screen means may be preferred. This may the case especially where excessive turbulence at the rear edge of the wall/screen 15 means.
  • the wall/screen means operates in the following manner.
  • Each of the particles still present in the circulating fluid (e.g. as a result of vortices or other factors) which is to be removed, is generally denser than the fluid itself and will thus have a large component of velocity and momentum in the direction of circulation.
  • Such particles which reach the height of the outlet 13 will thus be constantly entrained around the tank and will therefore be directed along, or close to, the wall/screen means 15.
  • Fluid which exits through outlet 13 is relatively slow- moving behind wall/screen means 15 and travels in the opposite direction to the main circulation. Due to the difference in densities between the fluid and the particles, the particles will in the main not be entrained with the fluid towards the outlet 13.
  • the wall/screen means Since the wall/screen means is open towards the bottom of the tank, those few particles that are drawn into the fluid behind the wall/screen means will fall under the force of gravity down below the wall/screen means again and will not exit via outlet 13 since the fluid is relatively slow-moving towards the outlet, allowing time for the particles to descend.
  • the speed of flow towards outlet 13 varies in dependence on the distance of the wall/screen means 15 from the tank wall 12, such that the smaller the distance is, the smaller the velocity is. The distance must thus be determined according to circumstances when constructing the tank. Particles of less density, such as certain wood chips, will not be affected by gravity and will remain in a floating state. Accordingly such particles will follow the upward circulation flow in the tank. Due to the wall/screen means however they cannot escape via outlet 13, but will eventually escape via the main outlet 17. From the main outlet these woodchips etc. will follow the liquid stream back to the chip chute, i.e. without causing any problems of reintroduction.
  • the wall/screen means has a vertical extension both above and below the outlet 13, which should be of a sufficient height to prevent vortex and/or other effects at the upper and lower 19 edge portions of said wall/screen means from drawing in solid particles from the main circulation into the reverse flow behind the wall/screen means.
  • the fluid inlet 11 is preferably arranged below the outlet 13 and the wall/screen means 15. In this manner, a large proportion of the solid particles in the inlet fluid will already have been separated out due to the combined centrifugal and gravitational forces before reaching the height of the outlet 13.
  • This outlet is arranged substantially centrally and, due to its central location, will be relatively free of dense particles since the centrifugal force will generally have caused these to migrate to the tank sidewall.
  • the wall/screen means may be designed in different manners comprising different patterns, shapes or widths etc. Moreover it would be possible to use more than one wall/screen means, e.g. a combination of two or more different wall/screen means faces in overlapping relationship with each other.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)

Abstract

La présente invention concerne un appareil destiné à éliminer les impuretés d'un fluide, en l'occurrence, un hydrocyclone doté d'un piège à particules inférieur. L'appareil se compose d'une cuve (10) à paroi latérale (12) sensiblement circulaire, et d'une entrée (11) de fluide dans la cuve, l'entrée du flux dans la cuve (10) étant assurée de sorte que celui-ci circule dans la cuve. Une sortie (13) est conçue de façon à évacuer de la cuve (10) le fluide dont les impuretés ont été éliminées. Dans la cuve, un organe paroi/écran (15) s'étend depuis un emplacement (16) sur la paroi (12) dans le sens de circulation du fluide et à travers la sortie (13). Un espace entre l'organe paroi/écran (15) et la paroi latérale permet au fluide de s'écouler de la cuve (10) en sens inverse au mouvement circulaire du fluide, ce qui donne un fluide relativement exempt d'impuretés.
EP94929702A 1994-09-01 1994-09-01 Separateur d'elimination des impuretes d'un fluide Withdrawn EP0783375A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/SE1994/000804 WO1996006684A1 (fr) 1994-09-01 1994-09-01 Separateur d'elimination des impuretes d'un fluide

Publications (1)

Publication Number Publication Date
EP0783375A1 true EP0783375A1 (fr) 1997-07-16

Family

ID=20393225

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94929702A Withdrawn EP0783375A1 (fr) 1994-09-01 1994-09-01 Separateur d'elimination des impuretes d'un fluide

Country Status (3)

Country Link
EP (1) EP0783375A1 (fr)
AU (1) AU7865894A (fr)
WO (1) WO1996006684A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE507386C2 (sv) * 1996-09-16 1998-05-25 Alfa Laval Ab Förfarande och anläggning för behandling av en förorenad massasuspension
SE507387C2 (sv) * 1996-09-16 1998-05-25 Alfa Laval Ab Förfarande och anläggning för behandling av en förorenad massasuspension
WO2023032069A1 (fr) 2021-09-01 2023-03-09 三菱電機株式会社 Dispositif d'élimination de corps étrangers

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE324144B (fr) * 1968-07-09 1970-05-25 Skardal K
DE2838173A1 (de) * 1978-09-01 1980-03-06 Temafa Textilmaschf Meissner Zyklonabscheider zum abscheiden von schwer- und staubteilen aus fasermaterial
DE4010516C1 (fr) * 1990-04-02 1991-10-24 Forschungszentrum Juelich Gmbh, 5170 Juelich, De

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9606684A1 *

Also Published As

Publication number Publication date
WO1996006684A1 (fr) 1996-03-07
AU7865894A (en) 1996-03-22

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