EP0419479B1 - A method and equipment for microatomizing liquids, preferably melts - Google Patents

A method and equipment for microatomizing liquids, preferably melts Download PDF

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Publication number
EP0419479B1
EP0419479B1 EP89900667A EP89900667A EP0419479B1 EP 0419479 B1 EP0419479 B1 EP 0419479B1 EP 89900667 A EP89900667 A EP 89900667A EP 89900667 A EP89900667 A EP 89900667A EP 0419479 B1 EP0419479 B1 EP 0419479B1
Authority
EP
European Patent Office
Prior art keywords
liquid
barrier
jet
gas
media
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
EP89900667A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0419479A1 (en
Inventor
Hans-Gunnar Larsson
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.)
HG Tech AB
Original Assignee
HG Tech 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 HG Tech AB filed Critical HG Tech AB
Priority to AT89900667T priority Critical patent/ATE93750T1/de
Publication of EP0419479A1 publication Critical patent/EP0419479A1/en
Application granted granted Critical
Publication of EP0419479B1 publication Critical patent/EP0419479B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
    • B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
    • B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/02—Spray pistols; Apparatus for discharge
    • B05B7/08—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point
    • B05B7/0807—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
    • B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
    • B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
    • B22F2009/088—Fluid nozzles, e.g. angle, distance

Definitions

  • the present invention relates to a method of atomizing a liquid to form a fine powder, where liquid, preferably metal melt, is mixed into a media jet consisting of gas and/or liquid, so that it is disintegrated into small particles, i.e. atomization is achieved.
  • the invention also relates to a means for performing said method.
  • Such atomization is effected by disintegration of a preferably vertical tapping stream or other pool of liquid, with the aid of preferably horizontal or vertical media flows consisting of gas or liquid.
  • the size of particles formed in a certain volume element in the atomization process is affected by a number of parameters.
  • the surface tension of the melt and the density and velocity of the atomizing medium are the most influential parameters, besides the geometrical design of the atomization process.
  • a larger or smaller proportion of the melt will be disintegrated to particles in a region further away from the nozzle, where the velocity is considerably less, in some cases even as low at 10% of the maximum velocity. This gives a coarse powder with a wide spread between the smallest and largest particles.
  • Another problem entails the difficulty of getting the atomizing medium to get a "grip" on the liquid, and a large quantity thus passes outside the actual atomizing region, with low effectivity as a result.
  • the method according to the invention aims at a solution of the problems mentioned above and these related thereto and is characterized in that in the method there is comprised projecting at a high rate of speed a first fluid medium jet containing disintegrated liquid into a barrier means comprising a second fluid medium jet, projected by a nozzle in a direction substantially 180 o to said first fluid medium jet, such that the said first medium jet and fine particles diverge away from and around said barrier means, thus increasing contact surface between said first fluid medium jet and said liquid and increasing intermixing there between and after diverging solidifying said disintegrated liquid into a fine powder downstream of said barrier means.
  • the atomization process takes place within a short distance of the nozzle, where the velocity of the atomising medium is still high, as well as a large proportion of the gas participating in the atomizing process. A high degree of efficiency is thereby obtained.
  • This method thus enables a radical reduction in the average particle size and less spread in the size distribution, at low cost.
  • the barrier consists of a counterdirected media flow of gas and/or fluid, i.e. the barrier in this case constitutes the limit/contact surface between the mixed stream and the counter-directed media jet.
  • the method can be applied to both vertical and horizontal atomizing processes. With a suitable choice of barrier, it is even possible to atomize a steel melt or alloys with an even higher melting point.
  • the invention also relates to a means for performing said method, and the features characteristic of this means are defined in the appended claims 8 and 9.
  • the medium for the media flow or the counter-directed media flow may be water, some other liquid such as liquid gas, or only gas such as nitrogen or argon or mixtures thereof. Alternatively the gas being blown in can be rotated.
  • a vertical atomizing chamber 1 having a casting box 2 for metal melt.
  • Media gas and/or fluid
  • a gas cooler 3 and a compressor 4 to nozzles in the chamber 1.
  • Atomized powder is carried from the chamber 1 via a pipe system to a cyclone 5 for treatment and separation.
  • Metal melt e.g. steel
  • Metal melt is tapped from the casting box 2 ( Figure 2a) through a tapping arrangement in the bottom of this box, in the form of a preferably circular tapping stream 6 flowing vertically downwards into an atomizing chamber 1 filled with inert gas.
  • a gas nozzle 7 consisting of an annular nozzle or several smaller nozzles.
  • the nozzle(s) create(s) an annular gas curtain 9 around the tapping stream which encounters (8) the tapping stream at an acute angle, some way from the nozzle(s) 7.
  • the barrier 10 of the invention is located at a suitable distance below the point of encounter.
  • the barrier 10 consists of a gas barrier 11. This is produced by directing a gas and/or fluid jet upwardly, preferably in the same centre line as the tapping stream and the gas curtain, at a suitable distance below the nozzle (s), i.e. a second jet is directed preferably immediately towards the first jet 9-6 which contains fragments of melt 13 in its central portion.
  • the velocity decreases in the region of the collision, and the pressure thus increases. Due to the increase in pressure, the gas expands radially outwards so that the velocity again increases. If the kinetic energy is equal in the two jets, the resulting direction will be substantially radial, i.e. perpendicular to the direction of the jets. The melt in the central portion of the first jet 13 will alter course in the collision region and will accompany the radially expanding gas, thus achieving efficient atomization.
  • the atomization process is further improved if the kinetic energy of the counter-directed jet is chosen less or greater than that of the first.
  • the expanding gas will assume a curved path, most resembling parabolic shape, ( Figure 2a).
  • the improved atomizing process is due to fragments of the melt drawn along with the gas being constantly forced to change direction, thus giving them greater exposure of the gas.
  • the kinetic energy in the counter-directed gas flow is advantageously chosen less than that in the first, thus producing the effect described above, while the overall direction of the gas/particle mixture will be obliquely downwards. If the ratio of kinetic energy is inverted the overall flow will be obliquely upwards.
  • the kinetic energy in the counter-directed jet may be 10 to 1000% of the first, preferably 30-60%.
  • the barrier may be obtained from a nozzle as shown in Figure 2b, with one or more central nozzles 14 for barrier jets.
  • auxiliary nozzles 15 can be arranged to prevent liquid (melt) from coming into contact with undesired parts of the barrier nozzle.
  • the barrier may preferably have a geometry congruent with the cross section of the portion of the gas jet mixed with melt 13.
  • the size of the barrier is suitably such that its longitudinal dimensions are equal to the cross section of the part of the gas stream mixed with melt, at the point of encounter, or up to 20 times greater, preferably 4 to 10 times greater than said cross section.
  • auxiliary nozzles suitably located, with the object of eliminating turbulence in critical areas, thus preventing molten particles from becoming attached.
  • auxiliary nozzles may have the appearance of those shown at 15 in Figure 2b.
  • Figure 4 shows a horizontal atomizing equipment with its atomizing chamber 19 and cyclone 20.
  • the atomizing equipment comprises a closed system, preferably kept under a certain overpressure (see Figures 1 and 4). This may be 500 mm water column, for instance, so that air is prevented from entering.
  • the casting box 2 is arranged at one end of the box (1, 19).
  • Figues 5a and 5b show atomization as performed in the equipment shown in Figure 4.
  • Medium 22 flows from nozzles 21 (for instance elongate, slot-shaped or a row or small nozzles) towards the tapping stream 23.
  • the mixed stream thus obtained then encounters a barrier (produced by one or more nozzles 25) and is deflected thereby, thus producing excellent atomization.
  • the auxiliary nozzles are arranged in Figure 5b as one slot-shaped nozzle 26 and several small, separate nozzles 27. The nozzle 26 may even produce the barrier itself.
  • the angle between the media jets may be 0 - 60 o , but is preferably 5 - 20 o .
  • the nozzles 21, 21 may be arranged to give two horizontally directed media jets, parallel in vertical equipment, with great extension vertically as compared with the width, and with an angle in the horizontal plane in relation to each other.
  • the zone described above will then be formed.
  • the tapping stream 23 will flow from the top, down in the vertical zone formed all along the height of the nozzle.
  • the stream will be successively disintegrated on its way down, and mixed into the passing atomizing medium.
  • Media jets with considerable extension in one direction can be achieved by means of slot-shaped nozzles or by a number of circular nozzles, for instance, arranged close together in a row.
  • the nozzles for the media jets may be designed for sub-pressure or over-critical pressure conditions (Laval nozzle).
  • the advantage of the arrangement of nozzles 21 described above is that a more homogenous mixing (partial atomization) of the liquid into the media can be achieved which, even after passing a barrier, results in a narrower fraction for the particles.
  • FIG. 3 shows an alternative embodiment of the method and means according to the invention.
  • An electric arc 30 is arranged between two electrodes 28, 29.
  • Media streams 31 gas and/or fluid
  • media jets from the opposite direction 32 act as barrier. Efficient atomization of the liquid 35 formed in the electric arc is obtained.
  • the liquid to be atomized is obtained from at least one of the electrodes 29.
  • liquid can also be obtained from a solid body which is melted by a laser or the like (not shown) in similar manner.
  • Feeding the electrodes in Figure 3 along, or the laser, can be arranged by means of a feeder 34.
  • the nozzles for both the first media and the barrier media may be annular, or may consist of several small nozzles.
  • the method according to Figure 3 is preferably carried out in a chamber similar to that described earlier (not shown).
  • Particles formed at the atomization are drawn into the gas jets towards the other end of the chamber, and before encountering the end of the chamber, they will have solidified to powder due to radiation and convective heat dissipation to the gas.
  • An outlet is arranged in the chamber, preferably at its end, towards which the gas/powder mixture flows.
  • the chamber is connected from the outlet by pipes, to a cyclone where the powder and gas are separated. After separation, the gas may travel to a compressor via a gas cooler, for recirculation to the atomizing nozzles.
  • the system includes other requisite valves, cooling equipment and control means for regulating gas pressure, temperature and the various media flows, etc.

Landscapes

  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
  • Nozzles (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Steroid Compounds (AREA)
  • Saccharide Compounds (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
EP89900667A 1987-12-09 1988-12-05 A method and equipment for microatomizing liquids, preferably melts Expired - Lifetime EP0419479B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT89900667T ATE93750T1 (de) 1987-12-09 1988-12-05 Vorrichtung und verfahren zur mikroatomisierung von fluessigkeiten, insbesondere schmelzen.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8704905 1987-12-09
SE8704905A SE462704B (sv) 1987-12-09 1987-12-09 Foerfarande vid atomisering av vaetskor och anordning foer genomfoerande av foerfarandet

Publications (2)

Publication Number Publication Date
EP0419479A1 EP0419479A1 (en) 1991-04-03
EP0419479B1 true EP0419479B1 (en) 1993-09-01

Family

ID=20370540

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89900667A Expired - Lifetime EP0419479B1 (en) 1987-12-09 1988-12-05 A method and equipment for microatomizing liquids, preferably melts

Country Status (9)

Country Link
EP (1) EP0419479B1 (fi)
JP (1) JP2703378B2 (fi)
AT (1) ATE93750T1 (fi)
AU (1) AU2821589A (fi)
BR (1) BR8807838A (fi)
DE (1) DE3883788T2 (fi)
FI (1) FI87053C (fi)
SE (1) SE462704B (fi)
WO (1) WO1989005196A1 (fi)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE507828C2 (sv) * 1992-01-28 1998-07-20 Hg Tech Ab Atomiseringsförfarande
GB9703673D0 (en) 1997-02-21 1997-04-09 Bradford Particle Design Ltd Method and apparatus for the formation of particles
DE19831335A1 (de) * 1998-07-13 2000-02-10 Michael Angermann Tröpfchenerzeuger für leitfähige Flüssigkeiten
SE9901667D0 (sv) * 1999-05-07 1999-05-07 Astra Ab Method and device for forming particles
DE10205897A1 (de) * 2002-02-13 2003-08-21 Mepura Metallpulver Verfahren zur Herstellung von partikelförmigem Material
US20040098839A1 (en) * 2002-11-27 2004-05-27 Pfizer Inc. Crystallization method and apparatus using an impinging plate assembly
FR2960164B1 (fr) * 2010-05-21 2014-03-28 Centre Nat Rech Scient Procede de production d'un materiau nanometrique et reacteur pour sa mise en oeuvre
JP5662274B2 (ja) * 2011-07-28 2015-01-28 株式会社東芝 流速及び粒径計測方法、ならびにそのシステム

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE901855C (de) * 1939-12-13 1954-01-14 Degussa Vorrichtung zum UEberfuehren von schmelzfluessigen Stoffen oder Stoffgemischen in feinverteilte Form
JPS59171307A (ja) * 1983-03-18 1984-09-27 Fujitsu Ltd タツプ係数切替方式
US4559187A (en) * 1983-12-14 1985-12-17 Battelle Development Corporation Production of particulate or powdered metals and alloys
JPS59214340A (ja) * 1983-12-15 1984-12-04 Nec Corp 振幅等化方式および振幅等化装置
NO853772L (no) * 1984-11-02 1986-05-05 Universal Data Systems Inc Fremgangsmaate for etablering av en kommunikasjonskanal, modem-kommunikasjonssystem og mikroprossesorstyrt modem.

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
Derwent's abstract No 30615/ E/15, SU 839694, Sibe Metal Inst. publ. 1981-06-26 *
Derwent's abstract No 76336 C/43, SU 719802, Sibe Metal Inst., publ. 1980-03-15 *
Derwent's abstract no 86 257345/39, SU 1210989, Zaporo Mech Eng Cons, publ. 86-02-15 *

Also Published As

Publication number Publication date
FI902863A0 (fi) 1990-06-08
WO1989005196A1 (en) 1989-06-15
AU2821589A (en) 1989-07-05
EP0419479A1 (en) 1991-04-03
SE462704B (sv) 1990-08-20
FI87053C (fi) 1992-11-25
JPH03501629A (ja) 1991-04-11
DE3883788D1 (de) 1993-10-07
SE8704905L (sv) 1989-06-10
SE8704905D0 (sv) 1987-12-09
JP2703378B2 (ja) 1998-01-26
DE3883788T2 (de) 1993-12-16
FI87053B (fi) 1992-08-14
BR8807838A (pt) 1990-10-23
ATE93750T1 (de) 1993-09-15

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