DE2246248A1 - PROCESS AND DEVICE FOR PNEUMATIC CLASSIFICATION OF FINE DISTRIBUTED SOLIDS - Google Patents

Description

Method and device for the pneumatic classification of

finely divided pests

The invention relates to a method and a device for the continuous pneumatic classification of finely divided Solids.

In practice, the pneumatic classification is finely divided solids generally Zentrifugalklassifizierern conducted These conventional Zentrifugalklassifizierer work in a vertical arrangement ₀ Horizontally arranged Zentrifugalklassifizierer are also known

For several years, innovations have been proposed in centrifugal classifiers, particularly directed to elements were to improve the selectivity. And numerous inventions have been made for the purpose that sand-like to clean any product left behind «,

oo / 2

309814/0818

The invention is based on the object of an improved method for classification, the classification process being differentiated into its basic components is to be, each of the components executable under essentially independent conditions with an extremely possible perfection should be and where the components should form an overall continuous whole.

This object is achieved with a method according to the invention by

a) a primary dispersion of the applied material to form an air suspension using the injection principle,

b) Separation of the praction contained in the suspension produced in a higher-lying horizontal centrifugal field into a punishment product and a coarser middle product, which is either recycled into the suspension produced in the primary dispersion stage or as a separate product is withdrawn and through

c) a secondary dispersion of the praction obtained by gravity from the air suspension in the second Dispersion stage is precipitated at a lower level, the dispersion being branched off by a Part of the whole air flow takes place, which is necessary for the classification into a coarse end product and a finer middle product is used, which is carried with the air upwards into the horizontal centrifugal field

becomes β / -,

3098 1 4/0818

Since the specified two levels of dispersion for the material that to be classified appear to be equivalent for most operations, it will be evident that, if so desired, theirs Number can be increased by following the pattern described

The centrifugal classification can also be carried out as a multi-stage process in such a way that the Peinanteeilispension a previous level be the task for a subsequent level can, which is carried out in a similar horizontal centrifugal field, which is on a higher level and with a higher acceleration value worked

The classification device for performing the method is designed according to the invention in such a way that a housing a fan a feeder a separator for the fine and a collecting container for the coarse end product are assigned, with an injector as the primary in a certain plane in the housing Dispersion stage is arranged and above this level at least one horizontal centrifugal classifier and wherein a second dispersion stage is also arranged below this level istc ■

As noted above, one of the essential features of the invention is the steps and elements used to _{achieve the utmost possible dispersion of the feed material o} Only carefully dispersed feed powders will result in a clean separation o

3098U / 0818

These sufficiently finely effective dispersion elements are one essential prerequisite for the error-free pneumatic classification process and the device «The whole effect according to the present invention, these elements are directed to this basic object, which is the case with the previously known classifiers has not received sufficient attention · The dispersion elements according to the present invention are designed in such a way that that they include an injector without moving parts, an injector without moving parts but for further reinforcement its effect with stationary counter barriers and an injector without moving parts that supports its effect is made by a mechanical part rotating at high speed.

The centrifugal classifier is preferably designed so that it only includes stationary parts. The other alternative is there in drum-like elements that rotate around a horizontal axis. The circumference of this drum can be from a number of one another there are spaced rods or ribs that are arranged parallel to the drum axis. The ribs can auoh seen in cross-section, as a triangular triangle, in the direction of pointing to the rotation, being trained "

To the classifier as a whole as a handy and simple unit to form, it is advantageous that the classifier housing, the first and second dispersion stages therein »the centric

fugal classifier,

3098U / 0818

the fines separator, the connecting air lines and the fan form a unit that worked with a closed circuit

The invention is explained below with reference to the drawing of exemplary embodiments explained in more detail

It show schematically

1 shows a tertiary section through a classifier;

2 shows a corresponding section through a classifier other design and

3 shows a similar section through a classifier in a further embodiment _o

As can be seen from FIG. 1, the device consists of one box-like housing 1, feed elements 2 for the material to be classified, from a separator 3 for the fine product, from a collecting container 4 for the coarse "end product, and an air connection line 5 between the separator 3 and a fan 6o primary dispersion elements 7 are in the front area of the Housing 1 arranged, and a centrifugal classifier 8 has a horizontal axis in the upper region of a rear part of the housing. The dispersion elements in Figure 1 only exist of stationary parts, the most essential being the air inlet duct 9, the material feed channel 10 and the mixing channel 11 for the air and the feed material, which together form a Form injector »

O 0/6

3G98U / 0818

The injector opens to the primary dispersion space 12, which is equipped with a set of flow guide plates 13 ″ The inlet of the air duct 9 is provided with an articulated flow control plate 14

In the Pig. 1, the centrifugal classifier 8 is formed only from stationary parts. Essential parts of this are the relatively wide inlet opening 151, a circular outlet opening 16 for the suspension carrying the fine product and a relatively narrow downwardly directed outlet slot 17 for the coarser middle product ₀ The opening 16 leads tangentially to the upper part of the separator 3o The secondary dispersion elements 18 comprise after Pig. 1 an air duct 19, a chimney-like feed duct 20, a secondary dispersion space 21 and a flow duct 22 which leads directly to the centrifugal classifier 8 “As can be seen, the primary and secondary dispersion elements and the primary and secondary dispersion spaces are clearly separated from one another

As continued from Pig. 1 can be seen, form the device housing 1, the primary dispersion elements 7f the secondary Dispersion elements 18, the centrifugal classifier 8, the Particulate matter separator 3, the air connection line 5 and the Blower 6 a unified system that works with a closed circuit. A line 23 connected to line 5 is, leads to an external dust collection system, which is not shown.

«O / 7 3098U / 08 1 8

The device according to FIG. 2 differs according to that of FIG Fig. 1 is only in two essential points the primary dispersion elements 7-. liier a series of stationary counter grids In addition, the centrifugal classifier assigned to 24 is designed in two stages in this case and comprises a primary one Centrifugal classifier 8 and a secondary centrifugal classifier 25 with smaller dimensions «,

The outlet opening 16 in the classifier 8 leads to a channel 26 which feeds the classifier 25. A circular outlet opening 27 is now tangentially connected to the cutter 3. A downwardly directed base seat 28 for the middle product leads either to a primary dispersion space 12 or to a separate collecting container (not shown) _e

The classifier according to FIG. 3 differs from those already described in that the dispersion elements 7 and the centrifugal classifier 8 now each contain a movable part. According to Figo 3, a dispersion drum rotates about a horizontal axis and is in the region of the mouth of the · primary dispersion stage 7 (Primärinjektor) disposed "The drum periphery consists of uniformly distanced rods ₀ The drum rotates at a desired speed, mediated by an externally arranged drives To To further improve dispersion, a stationary grid 30 is placed behind the drum 29.

.0 / 8 3098U / 0818

The centrifugal classifier 8 according to FIG. 3 represents one possible type of construction. The drum 31 rotates around one horizontal axis at a desired speed. The drum is preferably for a pure classification function and is not intended to provide an inward or outward flow of air when rotating on its own. Ana parts In this case, the drum circumference of conventional rods is formed from the same, equally spaced ribs 32, which are spaced apart are arranged from each other and parallel to the drum axis.

" ¹ Il

In order to achieve the recommended neutral effect, each When viewed in section, the rib is preferably an isosceles triangle in the direction of rotation.

The classification device works in principle as follows:

According to Fig. 1, the material to be classified is included in the task 2 introduced and fed at an angle, mediated by the inclination of the channel 10 of the primary dispersion stage 7, where the material gets into the rapidly flowing air exiting from the channel 9 and with this in the channel 11 according to the injection principle is mixed.

The suspension that forms in the process spreads in the primary dispersion space 12 of the housing 1. The solid fraction, contained in the suspension flow flows at a high speed and passes along the plates 13 the opening 15 in the centrifugal classifier 8, where the solids according to the known principle in the manner

3098U / 0818

be secured in such a way that the fine fractions of the air follow into the separator 3, while the coarser fractions with some fine fractions as a middle product pass back down through the outlet slot 17 into the primary dispersion chamber 12 are now have a new opportunity to get back to the classifier 8. The particles do not remain in the suspension, after contact, down by gravity in the chimney-like space 20 from _0, the fines are redispersed by the secondary dispersing step 18, which is designed as a simple injector. The air for this injector is supplied via a second air duct 19. The resulting dispersion spreads in the second dispersion chamber 21, from where the suspended fine fractions of the air follow upward through the channel 22 directly into the classifier 8, while the cleaned, coarse end product reached the collecting container 4 Separated air in separator 3.

Both fractions can be continuously discharged from the device in any suitable manner. The air with a certain very fine dust fraction flows from the separator 3 via the line 5 into the fan 6 and in a closed circuit back into the device. As shown in Fig. 1, the supplied material to be treated here an open task 2 ₀ In such a case, the blowing of dust by the task 2 is prevented by a diverted part of the air flow coming from the separator 3 via a Line 23 is led to a dust separator -

309814/0818

This results in little air being drawn in by the task 2 with the feed material · When using a closed feed system of any conventional type (not shown) instead The task open here does not require an external dust collector

The working principle of the device according to Figo 2 is essentially the same as in the case of FIG. 1. Stationary rows of counter grids 24 are used to achieve the dispersion effect the first dispersion stage 7 to strengthen »The two-stage centrifugal classifier leads to a very uniform Effect of sighting. As shown, the air suspension emerging from the classifier 8 forms via the opening 16 emerges, as such and without further effort, a well-dispersed feed suspension for the secondary centrifugal classifier 25 "into which it is introduced via the inlet duct 26" The reclassified fine fraction follows the air via the Opening 27 in the separator 3, where the solids from the air as already described, be separated. The coarser middle product passes down through the channel 28, either into the primary dispersion space 12, or into a collecting container (not shown) to be deducted as a separate product. It goes without saying that the centrifugal classifier has several May have stages in the sense of the type described. The advantage of such an arrangement is that the reclassification the dispersed suspension created in a previous centrifugal stage,

../11 309814/08 13

takes place instantaneously in a subsequent centrifugal stage, below a much higher g-value »This higher one The g-value is achieved by reducing the active volume of the subsequent centrifugal stage compared to the previous one by reducing the active radius or by reducing its depth in the direction of the axis or by both

In the device according to FIG. 3, the powder mixture is fed from the injector 7 to the dispersion drum 29, which rotates at a desired speed. The rotation of the drum causes a strong mechanical distribution and rapidly moving eddies, which can improve the dispersion of the powder _o This effect can are further intensified by a series of stationary counter grids 30 against which the flow strikes "In the case of the centrifugal classifier according to IPig", 3 the strength of the separation is determined by the particle size, which is in the I _a ge, the air flow between the ribs in the Drum 31 to follow ₀ The larger particles, when they hit the outer ribs of the drum, are pushed back into the space surrounding the drum, from where they enter the primary dispersion space 12 via channel 17 with the rest of the oversized particles as already described

Since the device is very compact, the individual units can easily be connected in parallel or in series. For normal industrial purposes are usually no more than two units connected in series are required.

.o / 12 309814/0818

The main control measures for a given device are the control of the air input volume, control between the fraction volumes used for primary and secondary dispersion, and control of the speed of the dispersion drums and centrifugal classifier when they are within the Provision is provided

The method and the device can be used for the separation of all such products that have hitherto already been used by a pneumatic classification in conventional classifiers were suitable. The method and apparatus are particular suitable for the production of extremely fine products, for example of so-called super cement, of fillers such as Talc or kaolin in the paper industry and for the wide range of products known as micropowders «

The applicability of the device for separations with unusual Characteristics are described on the basis of Tables 1 and 2, which result from test runs on a pilot plant to have.

The data in Table 1 resulted from a test facility,

which essentially corresponded to the device according to FIG. 1. The device housing had a height of 75 cm, a width of 60 cm and a depth of 20 om _e. The effective volume of the centrifugal classifier θ above the housing was approximately 12 dm ³ · _β

309814/0818

Apart from the fan 6, this system did not have any movable ones

The data in the table show that with a single pass of 400 to 1,500 kg a fine product was obtained in the separator of $ 95 in the order of 56 / U to 46 / U ₀ . as stated. These separations were achieved with a centrifugal classifier that had a volume of only 10 liters, whereby the stated energy consumption was significantly lower than it could ever be achieved in comparable cases. As indicated, the dust loading of the suspension which entered the cut-off switch was extremely high. The data which indicate the circulation loading here shows that in practical operation no more than two complete units in series are required for a peak separation

The data according to Table 2 were obtained in a test installation which essentially corresponded to that of FIG. 2, but without the grids 24e The dimensions of the device were the same as indicated above. The secondary centrifugal classifier 25 had an effective volume of about 6 dm ο moving parts inside were not used.

The corresponding data in Table 2 show that in this device a one-step treatment leads to a torture product of several hundred kilos, with a purity of 25 / U at

about $ 95,

co / 14

309814/0818

and with a very low energy consumption. A middle product was subtracted from the classifier 25 as a separated product. Corresponding data are contained in Table 2. The summation of the i'ein component and the mean product give the Lines F + M which correspond to a single-stage centrifugal treatment similar to that in Table 1 «In some points the corresponding data in Table 2 are even higher.

309814/0818

1 Test data for the iaassification of ground cement clinker in the direction of the gate. Fig.

fr = = =
Te rs
I. 1.
2. j, {task
I t / h
I. 1.S9 • 4.48 j
I. . t / h jfb the
i original I. 22.3
Io. 3 Fine product -37 r ¹ Γ .0 \
.S j -74 jx
I.
I. -105 _y u J 9-5 < 1
⁰ I. kWh / t.
Peinpro
duct .5 1.
1. 75
13th dust
loading .7 '
.4 Circula I. 260
1.14 1
I ι i 0.421:
0.346 4C. 6th -32 _y uj
1 95.
9k 2
2 9S .9 99.S
99.6 99.9
99.8 j 36
38 I. 1.
2. 1. 92 1
1 .6 tion be
charge 1.
• 2. 2.7S 4.42 O.7Ö7 27.8
19.Ο 93.6 ί
92.4! 94. 7th .2
.0 99.7 99.9 37 O.
1. 06
54 1 • O
• ^? . 347
14 ₇ 213
96 2 - 0.772
0.52s 46.8 93.1 93
91 2
.4 .1 99.3
99.3 99-9-
99.8 4l
44 · 1. 26th 2 .9 1.
2, ■ 3.14 I.300 32nd
19.Ο 91.2
SS.6 j
ί 92 5 93 .0
.6 99-3 99-9 42 .5 O.
1. 91
53 .2
.3 17 /
66 3 1.005
0-597 51.0 90.1 92
90 ,8th
.6 98
98 .9 99.1
j 99.1 99.8
99.S 42
46 1. 14th 2
1 .9 1.
2. 36.I
24.5 90.S!
87.6 i 92 .0 98 .2
.8th 99.1 99.S 43 0.
1. 91
34 1 .8th
.2 196
S4 4th 60.6 S9.6 90
8S .8th
.5 .0 98.4
■ 93.4 99.4
99.2 4S
, 50 O. OS 1
1 .6 NO 1.
2. 33 * 8
20.6 SS.4
85.6 90 .0 .2
.0 98.4 99 * 3 49 68
11 I.
1 .7
.6 -> ·
CD 5 54.4 87.3 90
■ 90 .8th
.0 • 1 98.8
9P.7 99.6
99.5 46
47 S4 2
1 .3 ■ £ * -
CO SS.2
87.2 90 .5 98.'s 99'6 46 2 I.602 j 87.8 The cement clinker is a α fineness of 87 $ 74A and 64 $
0.5 0/00 iriaethanolainin as a dispersing agent was added to the '37 / v on been ground.
Given mill. 1,257
O. S53 2.110 9 p
97 I.494
O.9II 97 2.405 96
95 96 91
91 91

Table 2 Test data in the classification of ground cement clinker in the device according to FIG. 2

request 6th __
task 15th product t / h I. 238 £ äer 7th -15 .
, 4 -20 - 1
U -32 μ 95 7 ° I. 25th I. 24 t
kVh / t dust i 1 60 • Kff / Circula spec. Upper Ur. 219 O .8th I. I. -XU 36 Fine product loading O. tion be area riginalaüf- 7th .8th 29 32 88 charge Fine O. 696 gift 3 78 • j. SS. 5 98 .8th 3. 1. 3S4 49ΟΟ 7th 26th middle O. 147 20th ^ 5 -> 65. 3 93 .8th 25th 47 2I9O ^F + M O. 19th 7th 62 .9 77. 4th 96 .4 37 1. ■ 0. 152 36 OQ Griese O. 679 39. C. 11 .0 10 .6 34 .2 33 26th 970 Fine . O. 5S4 60 O 60 . 7th 89 9 98 .8th 2. 1. 552 8th .78 middle O. 3SS 15th O 46 .2 64 , 2 90 .9 26th ■ 21 F + M O. 344 14th Currently 64 • 7 77 94 .9 37 1. 1. 233 Griese 1. 732 30th 4th 17th .9 24 , 4 43 .8th 32 17th Fine O. 04? 70. 6th 79 . 7th 39 .2 98 .2 2. 1. 616 9 Smock 0- 424 14th 6th 46 "1 64 .1 90 .1 .02 F + M O. 330 12th 8th 63 .2 77 .4 94 .4 .1. 1. 2SO Griese 2. 754 26th 4th 21 .0 29 49 .5 .14 Fine O. 615 73. 6th 77 ^ 8 86 .7 98 • 3 2 1. 695 lattel ^! O. 12th 47 64 .2 90 . 2 F + M O. 9. 64 76 .9 9k .8th 1 1· 347 Griese 2. 22nd 21 29 • 5 kl .3 , 3 t / ** 77. 6th ^l / 1. 1 O 2. 7th O 2 S. 1

The cement clinker turns into a fineness in the presence of o> 5 0/00 iTriaethsnolajnin
74> k, 595S 32 u and 52 # I5 a, ground

volume

Claims (2)

Claim. '_ ■ 1. Method for the pneumatic classification of finely divided pesticides, characterized by a) a primary dispersion of the abandoned material to an air suspension using the injection principle, b)! Separation of the contained in the suspension produced Fraction in a higher lying horizontal centrifugal field into a fine product and a coarser middle product, either in the primary product Dispersion stage generated suspension is returned or withdrawn as a separate product and through e) a secondary dispersion of the fraction which is precipitated by gravity from the air suspension in the second dispersion stage at a lower level, the dispersion being carried out by a branched rope of the entire air flow, which is used for the classification into a coarse end product and a finer medium product that is carried with the air upwards into the horizontal centrifugal field WUd ₀ 2. The method according to claim!, Characterized in that the centrifugal classification in several Steps are carried out in such a way that in each case the fine product suspension a preceding stage forms the feed suspension of the following stage, which in a corresponding Centrifugal field is carried out, 3098U / 0818 that has a higher level and works at a higher g-value. Apparatus for carrying out the method according to claims 1 and 2, characterized in that a fan (6) is a feed device in a housing (1) (2) A separator (3) for the fine, and a collecting container (4) for the coarse end product are assigned, in the housing an injector is arranged as the primary dispersion stage (7) in a certain plane and above this plane at least one horizontal centrifugal classifier (8.25) and a second dispersion stage (18) is also arranged below this level « 4 »Apparatus according to claim 3, characterized in that the primary dispersion stage (7) or _0, the injector of stationary parts and that consists essentially of an air inlet duct (9), a Materialaufgabekaiaal (10) and a mixing channel is formed (11)" 5 β device according to claims 3 and 4, daduroh characterized in that the stationary dispersion stage (7) has one which is rotatable and driven about a horizontal axis Dispersion drum is assigned " 6 ο device according to claim 3 to 5, daduroh. It is shown that the centrifugal classifier formed from stationary elements has a multi-stage design is, the outlet channel (16) of the previous stage ../3 3098U / 0813 the I-pole stage, which has a small, effective volume and which is arranged higher than the first stage _o 7 «device according to claims 3" to 5 "thereby. in that the Zentrifugalklassifizierer (8,25) each have a driven about horizontal axes separator drum (31) ₀ 8ο Device according to claim 7 »characterized in that the circumference of the viewing drum (31} is formed from a certain number of spaced apart ribs (32) running parallel to the drum axis, which, seen in cross section, are isosceles triangles with a point pointing in the direction of rotation -en are trained o 9ο device according to claims 3 to 8, characterized characterized in that the second dispersion stage (18) is designed as an injector » ΙΟ «. Device according to claims 3 to 9 »thereby gekennz e i without t that the housing (1), the primary and secondary dispersion stage (7 »18), the centrifugal classifiers (8.25), the separator (3) and the fan (6) with a connecting line (5) than with a closed one A closed-loop system o 309814/0818 ZO L e r s e i t e