EP0504451B1 - Procédé et appareil pour charger des particules - Google Patents

Procédé et appareil pour charger des particules Download PDF

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Publication number
EP0504451B1
EP0504451B1 EP19910104306 EP91104306A EP0504451B1 EP 0504451 B1 EP0504451 B1 EP 0504451B1 EP 19910104306 EP19910104306 EP 19910104306 EP 91104306 A EP91104306 A EP 91104306A EP 0504451 B1 EP0504451 B1 EP 0504451B1
Authority
EP
European Patent Office
Prior art keywords
tube
particles
electrode
insert
charging
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
EP19910104306
Other languages
German (de)
English (en)
Other versions
EP0504451A1 (fr
Inventor
Bernd Dr. Gellert
Andreas Kwetkus
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.)
ABB Asea Brown Boveri Ltd
ABB AB
Original Assignee
ABB Asea Brown Boveri Ltd
Asea Brown Boveri 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 ABB Asea Brown Boveri Ltd, Asea Brown Boveri AB filed Critical ABB Asea Brown Boveri Ltd
Priority to EP19910104306 priority Critical patent/EP0504451B1/fr
Priority to DE59107949T priority patent/DE59107949D1/de
Priority to ES91104306T priority patent/ES2090160T3/es
Publication of EP0504451A1 publication Critical patent/EP0504451A1/fr
Application granted granted Critical
Publication of EP0504451B1 publication Critical patent/EP0504451B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C7/00—Separating solids from solids by electrostatic effect
    • B03C7/006—Charging without electricity supply, e.g. by tribo-electricity, pyroelectricity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
    • B03C3/28—Plant or installations without electricity supply, e.g. using electrets
    • B03C3/30—Plant or installations without electricity supply, e.g. using electrets in which electrostatic charge is generated by passage of the gases, i.e. tribo-electricity

Definitions

  • the invention relates to a method for charging particles according to the introductory part of claim 1 and to a device for carrying out the method.
  • Coal particles are finely ground particles in a friction charger (TRIBO charger) by collisions with solids, e.g. Walls, charged.
  • Friction chargers of this type are described, for example, in the brochure "ESB electrostatic automatic powder coating systems", page 13, from the company ESB, Meersburg (FRG), undated. This charge strongly depends on the dielectric properties of the particles.
  • a good insulator is charged differently than a bad one, so that the good insulator material can be separated from the bad one in an electrical field. For example, in the treatment of coal dust, the sulfur-containing components are separated.
  • Frictional charging and subsequent electrostatic separation also play a role in other processes in which particles are to be applied or removed, e.g. when applying powder coatings on automobile bodies or when separating dusts from exhaust gases.
  • the contact charging of solids is strongly dependent on the electrical properties of the materials.
  • the charge density that can be achieved is generally proportional to the difference the electron work function, ie the energy required to extract an electron from the solid. In the technical application of this effect in a friction supercharger, special care must be taken to choose the right materials.
  • Another important criterion is the fluidic design, since it is a two-phase flow with electrically charged particles. For example, if the particles pass through a cylindrical tube in order to be charged by wall impacts, there is a charge gradient in the longitudinal direction of the tube between the entrance of the tube, where only a few particles are loaded, and the outlet, where many are loaded. In the tube itself, this leads to mutual interference between the particles, so that the efficiency of charging can be reduced.
  • a free-fall separator is known from DE-B-1,084,246, in which gas loaded with floating particles reaches a centrifugal chamber from above. Its end is provided with a conical insert made of material generating friction electricity. At the lower end of the centrifugal chamber, a cone is fastened in an electrically insulated manner from this and the insert. The cone has a plate in which a spray electrode is attached, which extends into the interior of the centrifugal chamber. The suspended particles, which are electrically charged as a result of frictional electricity, leave the centrifugal chamber at high speed and hit the cone, where they release their electrical charge. Since it is electrically insulated, the cone and thus the spray electrode are charged with high voltage. In this way, a significant increase in separation efficiency is to be achieved.
  • electrostatic centrifugal separators as are known, for example, from GB-A-1,152,218, a type of electrostatic pre-charging of the ones to be separated has been achieved or particles to be separated from one another. There, the particle stream crosses a constant electrical field that is present between the two walls.
  • the invention is based on the object of specifying a method for separation in which the charged particles leave the frictional charging region as quickly as possible after charging. It is also an object of the invention to provide a device which is suitable for carrying out the method.
  • the method according to the invention is particularly suitable for separating ash-forming and sulfur-containing constituents in pulverized coal and is distinguished by a high separation efficiency.
  • the device for carrying out the method according to the invention is characterized by a compact structure and enables the charged particles to leave the friction charging area as quickly as possible after charging.
  • a first electrode 2 running in the longitudinal direction of the tube is arranged in a first tube 1 which is at earth potential and has a negative potential with respect to earth potential.
  • a first tube 1 which is at earth potential and has a negative potential with respect to earth potential.
  • sieve-shaped extension 3 which has a funnel-shaped end 4 with an outlet opening 5.
  • the first electrode 2 extends into the funnel-shaped end 4 of the extension 3.
  • This approach 3 is usually made of metal and is at ground potential. However, it can also consist of a dielectric material. To prevent the formation of surface charges that are too large, which would distort the field too much, however, partial areas of the screen-like attachment 3 would have to be metallized, for example in the form of strips from top to bottom.
  • a second tube 6 coaxially surrounds the sieve-shaped attachment 3 while leaving an annular gap 7 and serves as a second electrode lying at positive potential.
  • a gas stream 8 symbolized by arrows can be introduced into the annular space 7 through this annular gap 7.
  • a collecting funnel 9 is provided under the outlet opening 5.
  • a rotationally symmetrical guide device 10 is arranged at the lower end of the second pipe 6 and within the same.
  • the first tube 1 consists of a material suitable for optimal frictional charging. Alloys of metals with rare earths, such as lanthanum, cerium, cerium iron, or metal parts coated or vapor-coated with rare earths are particularly suitable. It is particularly advantageous to insert an insert 11 made of such a material into the tube 1.
  • the insert 11 consists of a spirally wound metal band, which rests everywhere on the inner wall of the tube 1 and is replaceable.
  • a spiral insert 11a with turns spaced apart from one another and thus enlarged surface made of the specified material can also be used according to FIG. Another possibility according to FIG.
  • this insert is to insert an insert 11b into the interior of the tube 1, which is distanced from the inner wall and is electrically insulated both from the tube 1 and from the inner electrode 2.
  • this insert consists of a spiral made of round wire made of the special material mentioned, the individual turns not touching one another.
  • the inner diameter of the insert 11b and its distance from the wall of the tube 1 depends on the size of the electric field and must be chosen so that no additional arcing occurs.
  • the operation of the device described above can be seen from the following:
  • the mixture containing the particles to be separated is fed at the upper end of the tube 1 in the direction of the arrow.
  • the particles are negatively charged by contact with the tube walls.
  • the low work function of the rare earths ensures a high negative charge of the particles.
  • the field is used for accelerated discharge at the end of the tribo-charger (pipe 1). Particles charged with the wall once are additionally driven to the wall by the electric field and experience multiple impacts, which leads to a higher charge especially in the case of insulating particles.
  • the field strengths used should be as high as possible and are in the range from a few kV / cm to a few 10 kV / cm.
  • the particles charged in this way are deflected in the sieve-shaped approach under the influence of the field acting between the inner electrode 1 and outer electrode 6 to the (positive) outer electrode 6 and conveyed through the stitches 12 of the sieve-like approach 3.
  • the particles Before reaching the positive electrode (tube 6), the particles are entrained and discharged by the outer gas stream 8 at a suitable flow rate.
  • Negatively charged particles that reach the positive electrode lose their charge can be removed from the electrode by suitable devices, for example tapping devices, brushes or the like, and can be fed back to the charger. The same applies to particles that have not received sufficient charging in the charger. These pass through the lower part of the funnel-shaped end 4 into the collecting funnel 9 and are also returned.
  • the present invention was explained on the basis of a coaxial arrangement of inner tube 1, inner electrode 2 and outer electrode (second tube 6).
  • plate arrangements are also conceivable.
  • the coaxial arrangement has the advantage of having a particularly homogeneous field (without edge losses).

Claims (7)

  1. Procédé pour le chargement électrostatique de particules en faisant passer un courant de particules au travers d'un chargeur par frottement, le chargement des particules dans le chargeur par frottement étant assisté par un champ électrique, caractérisé par le fait que le chargement dans le chargeur à frottement est assisté par un premier champ électrique appliqué depuis l'extérieur et que les particules chargées, après avoir quitté le chargeur par frottement sous l'effet d'un deuxième champ électrique de polarité inverse appliqué depuis l'extérieur, sont séparées de celles qui ne sont pas encore chargées et sont déviées vers l'extérieur par l'influence de ce champ, et que les particules déviées sont transportées vers l'extérieur au travers d'un courant d'air supplémentaire (8) qui est guidé en-dehors du chargeur par frottement (1) et qui agit sur les particules chargées seulement après le chargement par frottement.
  2. Appareil pour exécuter le procédé conforme à la revendication 1, caractérisé essentiellement par un tube cylindrique (1) avec au moins une première électrode (2) au potentiel négatif s'étendant dans le sens longitudinal du tube et au moins une deuxième électrode (6) au potentiel positif qui est disposée dans le sens du courant des particules en aval dudit tube (1), la partie inférieure dudit tube étant réalisée sous forme de filtre ou présentant un embout (3) de type filtre, lequel sert de zone de séparation, ladite zone de séparation étant disposée dans la zone d'action du champ électrique entre la première (2) et la deuxième électrode (6), et par le fait qu'un courant de gaz auxiliaire (8) peut être injecté dans l'espace annulaire (7) entre les deux tubes (1, 6) dans le sens du courant de particules.
  3. Appareil conforme à la revendication 2, caractérisé par le fait que le tube cylindrique (1) est composé d'un matériau ayant un faible travail de séparation, de préférence des terres rares, ou est recouvert ou vaporisé à l'intérieur avec un tel matériau.
  4. Appareil conforme à la revendication 2, caractérisé par le fait que dans le tube (1) se trouve un insert (11 ; 11a), de préférence en forme de spirale, en un matériau ayant un faible travail de séparation, de préférence des terres rares, ou recouvert ou vaporisé d'un tel matériau, lequel insert (11) repose sur la paroi intérieure du tube (1).
  5. Appareil conforme à la revendication 2, caractérisé par le fait que dans le tube (1) se trouve un insert (11b), de préférence en forme de spirale, en un matériau ayant un faible travail de séparation, de préférence des terres rares, ou recouvert ou vaporisé d'un tel matériau, lequel insert (11b) est maintenu à distance de la paroi intérieure du tube (1).
  6. Appareil conforme à l'une des revendications 3 à 5, caractérisé par le fait que ledit matériau est du lanthane, du cérium ou du ferro-cérium ou un alliage contenant l'une de ces substances.
  7. Appareil conforme à l'une des revendications 2 à 6, caractérisé par le fait que la première électrode (2) est disposée dans la zone centrale dudit tube (1), et que la deuxième électrode (6) est également réalisée en forme de tube avec un diamètre supérieur à celui du premier tube (1) et se raccorde immédiatement à l'extrémité du premier tube (1) se trouvant en aval du courant.
EP19910104306 1991-03-20 1991-03-20 Procédé et appareil pour charger des particules Expired - Lifetime EP0504451B1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP19910104306 EP0504451B1 (fr) 1991-03-20 1991-03-20 Procédé et appareil pour charger des particules
DE59107949T DE59107949D1 (de) 1991-03-20 1991-03-20 Verfahren und Einrichtung zur Aufladung von Partikeln
ES91104306T ES2090160T3 (es) 1991-03-20 1991-03-20 Procedimiento y dispositivo para la carga de particulas.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19910104306 EP0504451B1 (fr) 1991-03-20 1991-03-20 Procédé et appareil pour charger des particules

Publications (2)

Publication Number Publication Date
EP0504451A1 EP0504451A1 (fr) 1992-09-23
EP0504451B1 true EP0504451B1 (fr) 1996-06-19

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ID=8206545

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19910104306 Expired - Lifetime EP0504451B1 (fr) 1991-03-20 1991-03-20 Procédé et appareil pour charger des particules

Country Status (3)

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EP (1) EP0504451B1 (fr)
DE (1) DE59107949D1 (fr)
ES (1) ES2090160T3 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE60012989T2 (de) * 2000-01-21 2005-09-08 The University Of Western Ontario, London Reibungsaufladung und elektrostatisches trennen von gemischten elektrisch isolierten teilchen
CN106000654B (zh) * 2016-05-23 2017-10-27 中国矿业大学 一种颗粒反向进料摩擦电选分离装置

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE829132C (de) * 1944-05-10 1952-01-24 Metallgesellschaft Ag Verfahren und Einrichtung zur elektrostatischen Trennung von Zwei- oder Mehrstoffgemengen
DE1084246B (de) * 1956-03-08 1960-06-30 Otto Schmid Dr Ing Fliehkraftabscheider in Zyklonbauweise
BE688840A (fr) * 1965-10-25 1967-03-31

Also Published As

Publication number Publication date
ES2090160T3 (es) 1996-10-16
DE59107949D1 (de) 1996-07-25
EP0504451A1 (fr) 1992-09-23

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