Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
  • B07B7/00—Selective separation of solid materials carried by, or dispersed in, gas currents
  • B07B7/08—Selective separation of solid materials carried by, or dispersed in, gas currents using centrifugal force
  • B07B7/083—Selective separation of solid materials carried by, or dispersed in, gas currents using centrifugal force generated by rotating vanes, discs, drums, or brushes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
  • B07B11/00—Arrangement of accessories in apparatus for separating solids from solids using gas currents
  • B07B11/04—Control arrangements

Definitions

• the present invention relates to a pneumatic separator with centrifugal action intended to classify a granular material into a fine fraction and a coarse fraction and comprising a rotor with vertical axis provided with blades regularly distributed on its periphery, guide vanes arranged around the rotor, according to the generators of a fictitious cylinder, and capable of communicating to a current of air or other gas entering said fictitious cylinder a rotational movement around the axis of said cylinder, and an envelope in which the rotor and the guide vanes and which is provided with one or more inlets for air and for the material to be classified, an outlet orifice placed above or below the rotor and through which the charged air stream is drawn of the fine fraction of the material and at least one outlet for the coarse fraction, the air entering the rotor at its periphery, through the channels formed between the blades, and circulating nt inside the rotor to the outlet.
• the material to be classified and the air stream can be introduced separately inside the annular section space delimited by the guide vanes and the rotor, or the material to be classified can be suspended in the air stream before it is admitted into said space, through the blades; the air stream then enters the rotor and is discharged through the outlet.
• the air stream and the material to be classified are rotated around the axis of the rotor in the annular section space between the rotor and the guide vanes.
• the particles constituting the coarse fraction of the material are projected by the centrifugal force generated by this rotation against the guide vanes and fall by gravity into a collecting hopper provided with an evacuation orifice, while the particles constituting the fine fraction are entrained by the air flow through the rotor and the central outlet.
• the separated fine fraction contains practically all the particles whose size is smaller than a first dimension while the coarse fraction contains practically all the particles whose size is larger than a second dimension, larger than the first.
• the two fractions contain particles whose size is between the first and second dimensions. This results in a partition curve comprising two substantially horizontal portions connected by an inclined portion whose slope characterizes the separator.
• the distribution of particles of intermediate size in one or the other of the fractions characterizes the cutting precision of the separator. In general, it is sought to obtain, by construction, a cut as clear as possible between the two fractions, that is to say to reduce the difference between the first and second dimensions, which results in a curve of steep slope sharing.
• the product which one seeks to obtain must have a particle size distribution different from that of the fraction, fine or coarse, obtained by means of a separator of this type. This is in particular the case of the cement obtained by crushing by compression of the clinker.
• the only solution to solve this problem was to use two separators placed in series or in parallel and adjusted for different cutout dimensions. This solution is expensive.
• the object of the present invention is to improve the separators of the type concerned so that it is possible to adjust the slope of the partition curve in a simple manner, that is to say to modify the particle size distribution of the particles whose the size is between the first and second dimensions.
• the separator object of the invention is characterized in that the air circulating in the rotor is divided into at least two separate streams, and the rotor is equipped with means for adjusting the speed and / or the flow rate of at least one currents. If the velocities of the two air streams in the channels formed between the rotor blades are set to different values, the drag forces exerted by the two streams on a particle of given mass and dimensions will be different; in the channels where the air current circulates at reduced speed, the balance between the drag forces and the centrifugal forces, which corresponds to the theoretical cut-off mesh, will occur for a smaller particle size than that for which this balance occurs in other channels where the air speed is higher.
• the means for adjusting the speed and / or the flow of the air currents can be constituted by means for varying the inlet section of at least some of the channels formed between the blades of the rotor and / or by means to vary the passage section of the openings through which the air currents escape from the rotor.
• the rotor is divided into sectors by vertical partitions arranged radially and each sector communicates with the air outlet orifice through an opening provided with means for adjusting the passage section which may be formed, for example, by pivoting shutters or diaphragms; in this embodiment, the radial partitions fulfill the anti-vortex function of the second set of blades of the separator which is the subject of French patent n ° 90 01673 in the name of the applicant.
• each plate being movable, for example by rotation about an axis parallel to the axis of the rotor, between a first position where it leaves practically the entire section of the respective channel free, and a second position where it virtually completely closes the channel.
• certain blades of the rotor can be orientable around vertical axes so that their ends can come to bear on a neighboring blade to close the channel which they delimit.
• Another solution consists in making the blades in two parts: a fixed part and a mobile part, which can be rotated around a vertical axis.
• a fixed part For example, one of the faces of the blade can be fixed and the other movable and able to pivot around a vertical axis located near the periphery of the rotor to come to bear on the neighboring blade to close the channel that 'they form.
• the radially outer part of the blade can be fixed and its inner part rotatable, the movable parts of two adjacent blades can be brought into abutment against one another to close the channel delimited by the two blades.
• Figure 1 is a diametrical sectional view of a separator rotor according to the invention
• Figure 2 is a top view of the rotor of Figure 1, the ring partially closing the rotor at its upper part having been removed on one half of the rotor;
• Figure 3 is an enlarged view of a detail of the rotor
• Figures 4 and 5 are views similar to Figure 3 illustrating alternative embodiments
• Figure 6 is a diametrical sectional view of another separator rotor according to the invention.
• Figure 7 shows the partition curves of a conventional separator and the separator object of the invention.
• the separator which is the subject of the invention is of the type described in French patent n ° 90.01673 to which reference may be made for more details. As described above, it comprises a rotor with a vertical axis, guide vanes arranged around the rotor and an envelope in which the rotor and the guide vanes are enclosed and which is provided with one or more inlets for the product to be classified and for the air stream, one or more outlets for the coarse fraction and a central outlet for the air stream charged with the fine fraction of the product.
• the rotor 10 is fixed to the lower end of a vertical shaft 11 mounted, by means of rolling bearings, in a tubular support 12 fixed to the ceiling of the envelope of the separator.
• the shaft is coupled to a variable speed control group allowing the rotor to rotate at the desired speed.
• the rotor has a large number of vertical blades 14 regularly spaced around its periphery and whose lower and upper ends are fixed, respectively, on a bottom 16 and on a ring 18.
• a cylindrical ferrule 20 fixed on the inner edge of the ring 18 defines an outlet passage for the air charged with particles of small dimensions which have entered the rotor through the channels 15 formed between the blades 14. This ferrule is connected, by a rotating joint, to the lower end of a discharge duct 22 passing through the ceiling of the separator casing.
• the interior of the rotor is divided into four equal sectors by four vertical partitions 24 arranged radially. These partitions are fixed on the bottom 16, on the ring 18 and on a ferrule 26 surrounding the lower part of the tubular support 12 and itself fixed on the bottom 16.
• the outlet opening delimited by the ring 18 and the ferrule 26 is partially closed by pivoting flaps 28 (two by sector in the embodiment shown).
• Each flap is fixed on a shaft 30 mounted on bearings fixed on the ring 18 and the ferrule 26.
• a square provided at the outer end of each shaft 30 makes it possible to adjust the orientation of the flaps and, consequently, the section of the exit opening of the respective sectors, and a locking system keeps the shutters in the desired position, after adjustment.
• one blade 14 out of two is formed by a fixed part 31 constituting the active face and a movable part 32 orientable around a vertical axis 33 located near the edge blade attack (see Figure 3).
• This part 32 is movable, between a first position (represented by a solid line in FIG. 3) where it is pressed against the fixed part 31 of the blade, so as to leave free the entry of the channel 15, and a second position (shown in dashed lines) where it closes completely this entry.
• the orientation of the moving parts of the blades can be controlled individually or in groups. These two-part blades must be distributed over the periphery of the rotor so that it is balanced.
• FIG. 4 shows another embodiment of the means for closing off certain channels 15 of the rotor.
• the two blades delimiting a channel are in two parts: an external part 31 'which is rigidly fixed to the structure of the rotor and a lower part 32' which is able to pivot around a vertical axis 33 '.
• a control mechanism, not shown makes it possible to move the movable part 32 'of each blade between two positions: a first position, shown in solid lines in FIG.
• the means for closing the channels consist of pairs of vertical plates 40 placed inside the rotor, the two plates of a pair being articulated by their inner edge on the same vertical axis. 42 disposed in the median plane of the channel.
• a cam 44 placed between the two plates and controlled by an appropriate mechanism makes it possible to separate the two plates to bring their free end into abutment against the blades 14 and close the outlet of the channel 15, as shown in solid line in the figure.
• the cam is rotated to bring it into the median plane of the channel, the plates 40 are pressed against the cam by centrifugal force, as shown in phantom in the figure, and the outlet of the channel 15 is almost completely clear .
• certain blades 14 could be orientable by being mounted so as to be able to pivot on the rotor around vertical axes located near their leading edge and to abut against the adjacent fixed or orientable blades to close off the corresponding channels 15.
• the separator In service, the separator is incorporated in a circuit, open or closed, where a gas flow, for example an air flow, circulates.
• a gas flow for example an air flow
• the air stream Upon entering the rotor, the air stream is divided into as many elementary streams as there are channels 15 between the blades 14.
• these elementary streams are grouped in each sector of the rotor into four secondary streams which escape through the outlet opening delimited by the ring 18 and the ferrule 26. If all the flaps 28 are in the vertical position and if all the channels 15 are open, the flow rates of the four secondary currents are equal and the speeds elementary currents are equal; the operation of the separator is the same as that of a classic separator.
• the particle size for which the centrifugal and drag forces are balanced (theoretical cutoff mesh) will be larger in the first sector than in the others. Everything therefore happens as if we had two separators in parallel working with different cut-off meshes and whose fine fractions would be mixed at the exit of the separator.
• FIG. 7 shows by way of example the partition curves of a conventional separator, for two cut-off meshes, and of a separator according to the invention.
• the partition curve gives the weight proportion, expressed in%, of the particles of given size in the coarse fraction; we would get an inverted curve for the fine fraction.
• the three curves are combined.
• the dashed curve corresponds to a conventional separator whose theoretical cutoff mesh is 50 ⁇ m
• that in dotted lines corresponds to a conventional separator whose theoretical cutoff mesh is 105 ⁇ m.
• the curve in solid line was obtained with the separator of the invention; it can be seen that its slope is lower than that of conventional separators, which means that in the range 20-200 ⁇ m, the particle size is more spread out.
• the invention therefore makes it possible to have a partition curve with adjustable slope and, consequently, to obtain a finished product having the desired particle size distribution in a given particle size range by varying both the speed of the rotor and the orientation.
• the rotor could be designed as shown in FIG.
• the rotor is provided with means such as those illustrated in FIGS. 3, 4 and 5 for closing off some of the channels formed between its blades, over at least part of their height, and with means such as flaps 28 for adjusting at least one outlet openings.
• the rotor could be divided into more than two superimposed parts.
• Means other than pivoting flaps, for example diaphragms, could be used to adjust the section of the outlet openings of the rotor.

Landscapes

• Centrifugal Separators (AREA)
• Combined Means For Separation Of Solids (AREA)
• Glass Compositions (AREA)
• Lubricants (AREA)
• Cyclones (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

Family

ID=26232337

Family Applications (1)

Country Status (14)

Families Citing this family (20)

Family Cites Families (34)

• 1995
  • 1995-11-21 FR FR9513764A patent/FR2741286B1/fr not_active Expired - Lifetime
• 1997
  • 1997-04-15 CA CA002257674A patent/CA2257674C/fr not_active Expired - Fee Related
  • 1997-04-15 US US09/202,471 patent/US6273269B1/en not_active Expired - Fee Related
  • 1997-04-15 CZ CZ19983924A patent/CZ292237B6/cs not_active IP Right Cessation
  • 1997-04-15 UA UA98126592A patent/UA63905C2/uk unknown
  • 1997-04-15 JP JP54353798A patent/JP3999278B2/ja not_active Expired - Fee Related
  • 1997-04-15 AT AT97918235T patent/ATE270159T1/de not_active IP Right Cessation
  • 1997-04-15 DK DK97918235T patent/DK0918573T3/da active
  • 1997-04-15 WO PCT/FR1997/000678 patent/WO1998046371A1/fr not_active Ceased
  • 1997-04-15 AU AU26435/97A patent/AU741249B2/en not_active Ceased
  • 1997-04-15 EP EP97918235A patent/EP0918573B1/de not_active Expired - Lifetime
  • 1997-04-15 PL PL97330322A patent/PL186138B1/pl not_active IP Right Cessation
  • 1997-04-15 DE DE69729731T patent/DE69729731T2/de not_active Expired - Lifetime
  • 1997-04-15 ES ES97918235T patent/ES2224236T3/es not_active Expired - Lifetime
• 2001
  • 2001-04-16 US US09/835,150 patent/US6318559B2/en not_active Expired - Fee Related

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