EP0758931B1 - Reversing counterflow separator - Google Patents

Description

The invention relates to a deflection counterflow classifier the preamble of claim 1.

State of the art:

So-called air classifiers are used for the dry classification of fine-grained solids are used. The separation feature is that Final velocity of the grains in the air. Especially such sifters can also be used to clean an mainly in the form of granules and particles bulk mixture containing different sizes be used. Because of different Manufacturing processes can bulk goods very have different distribution spectra. Lying there Plastics in the form of granules, which with abrasion or are mixed with dust particles. Is the size of the Granules in the order of about 2 to 5 mm for the diameter or the length of the granules, so the In contrast, dust particles only a size of z. B. 50 microns on. In the case of plastic granules, there are also occasionally larger particles in front that also have angel hair or bird nests are called, which are disc, ball or spherical can and a diameter of about 2 cm to 10 cm exhibit. Such substances occur in particular pneumatic conveyance. That through the pipeline conveyed granulate rubs along the pipe, warmed up itself and forms adhesive threads or foils that always tear off or peel off.

A well-known air classifier for the treatment of such substances is in DE 42 35 260 A1 with indication of further status described the technology.

For the treatment of such bulk goods is from the DE-OS 1 905 106 a so-called diverting countercurrent sifter became known in which the bulk material to be treated is fed to a deflection sifter via a conveying gas flow. This is particularly the case in the conveying gas flow in the deflector bulk material conveyed downward from one opposite directional separation gas flow detected after the conveying gas flow redirected towards the top and the lighter, smaller and especially dusty particles in the deflected Carrying gas flow entrains while heavier particles are due the particle speed and inertia Penetrate the separation gas stream and in the lower area of the Be caught in a sifter.

From the literature: Special print from vt "Process engineering" 16 (1982) No. 7/8, pages 640 to 648 a deflection counterflow classifier according to the preamble of the claim 1 became known, which also for the treatment of a Bulk material flow serves. The deflection countercurrent sifter as a very efficient facility for the separation of Splinters, dust, threads or the like Plastic granules described. On those in this Literature described mode of operation of this diverting countercurrent sifter is hereby expressly referred to.

Already in this reference is the description of another riser gravity classifier indicated that the speed profile inside the pipe over the Pipe cross section varies, the air speed drops towards zero in particular towards the wall. Fine particles, those that come close to the wall fall into it Coarse material if it is not affected by air turbulence and ins Inside the pipe are transported back. This disadvantage is in the one described below in this reference Deflecting countercurrent classifier explicitly not mentioned, because in this case within the intended mouth of the Bulk material delivery line high particle accelerations occur, causing particles above a certain size the line of sight in front of the outlet penetrate and separated in the lower collecting container and be carried out. All smaller particles, as well as threads and Stripes are easily braked in the line of sight and carried away by the deflected air flow. The known Deflecting sifter therefore solves the problem of sighting the parts to be separated to a satisfactory extent.

Advantages of the invention:

The invention has for its object that from the above Literature "process engineering" known state of the art Improve technology to make it even more efficient Separation between larger particles and especially one Plastic granules and the associated Contaminants such as splinters, dust, threads or the like is possible.

This task is based on a diverting counterflow sifter according to the preamble of claim 1 by the characterizing features of claim 1 solved.

Advantageous further developments and Improvements to the counter flow classifier according to the main claim specified.

The invention is based on the basic idea that a Sighting, d. H. a separation of different components only is sufficient if all areas of a bulk material flow can be detected. From the beginning "Process engineering", it is mentioned known that the air speed of a flow in a conveyor pipe towards the wall drops towards zero. This However, the technical effect is in a diverting countercurrent sifter neglected insofar as that in the Sifting room bulk material feed line penetrating from above concentric, d. H. is inserted in the middle so that the falling bulk flow is not in the anyway Wall area of the classifier arrives because it was previously from the ascending separation gas flow is detected and treated. A however, such an approach ignores the fact that the Bulk material flow also inside the bulk material delivery line is subject to a speed profile that the desired acceleration of the particles at least in respective wall area prevented. By the used central tube to form an annular Acceleration channel in the bulk material delivery line results one radially inside and one radially external cylinder surface, between which the sets the speed profile described. Alike forms what continues downwards through the classifier central tube a desired ring cross section for targeted Feeding the upward separation gas stream to Mouth area of the bulk material conveying line. This one too Ring channel for the separation gas flow forms a radial inner and radially outer cylinder surface with a corresponding circumferential speed profile.

According to the invention, in particular on the radial inner cylinder surface both in Acceleration area of the bulk material conveying line in the form of an annular channel as well preferably in the annular Flow channel of the separation gas flow a surface structure selected the cylinder surface, which should avoid that the air speed towards the wall in the previous measure against Zero drops. In other words, it should Speed profile of the air speed within the specified ring channels are designed so that in Wall area of the respective ring channels no dead zones form in which the granules can fall through. this will for example in the described prior art in the Literature reference "process engineering" by a zigzag-shaped Sifter achieved, d. H. those in the wall area of the air flow of the separation gas flow not detected particles are always directed back into the gas flow.

The present invention takes a different approach to achieve this goal by the surface structure is designed such that increased turbulence in the Form wall area that to a possible rectangular velocity profile of the air flows to lead. The in the reference "Process engineering" specified zigzag shape of the air classifier itself for example as a surface structure on the Cylinder jacket surfaces applied in a suitable place to especially in the wall area to increased air turbulence respectively.

In this way, all in the bulk material conveying line larger particles accelerated in the wall area, too that they are able to keep the separation gas flow in the viewing zone to penetrate. Would not such particles in accelerated to the extent necessary, these would be from Separating gas flow due to its low speed captured and carried upwards out of the classifier. This would cause unnecessary losses to the bottom of the Sifter to collect granules.

Furthermore, the speed profile achieved in the below the outlet opening of the bulk material conveying line existing line of sight a detection of the in the Lighter parts that face upwards to be discharged from the classifier, since No longer set dead zones. Of the Efficiency of the deflection counterflow classifier is based on this Way vastly improved.

Fig. 1

eine Gesamtansicht eines Umlenk-Gegenstrom-Sichters im Längsquerschnitt und

Fig. 2

eine vergrößerte Darstellung der Sicht-Zone des Sichters, wobei die linke Figurenhälfte den Stand der Technik und die rechte Figurenhälfte eine erfindungsgemäße Ausbildung darstellt.

Further details and advantages of the invention emerge from the drawings and from the exemplary embodiment described below. Show it

Fig. 1

an overall view of a deflection countercurrent classifier in longitudinal cross section and

Fig. 2

an enlarged view of the viewing zone of the classifier, the left half of the figure represents the prior art and the right half of the figure represents an embodiment of the invention.

Description of the embodiment:

1 shows a deflection-counterflow classifier 1 according to the invention, which consists of a vertically oriented, cylindrical classifier cylinder 2 with a longitudinal axis 3 of symmetry. The entire deflection-counterflow classifier 1 has a height h ₁ , the classifier cylinder 2 a height h ₂ . In the upper opening 4 of the classifier cylinder 2, a bulk material conveying pipe 5 with a height h ₃ is concentrically let in, which is located above the height h ₄ within the classifier cylinder 2. The vertical bulk material conveying pipe 5 has an upper deflection flange 6, from which a connecting piece 7 leads laterally to a pneumatic bulk material feed line 8. The bulk material feed pipe 5 and / or the bulk material feed line 8 can also be referred to as a "bulk material feed line".

A central tube 9 with a height h ₅ is located within the classifier cylinder. The central tube 9 is fastened in the lower region of the classifier cylinder 2 by means of cross-shaped fastening webs 10. In the upper area, a conical tip 11 extends to the lower edge of the upper deflection flange 6.

In the lower area of the deflection-counterflow classifier 1 there is a conical outlet funnel 12 with a height h ₆ , which is extended upwards by a cylinder tube 13 with a height h ₇ . A gas inlet connector 14 is arranged on the side of the cylinder tube 13. The classifying cylinder 2 protrudes approximately over the height h ₇ into the cylinder tube 13.

The cylinder tube 13 has a diameter d ₁ , which is greater than the diameter d _{2 of} the lower part 15 with a height h _{8 of} the classifying cylinder 2. This results in an annular channel 16 within the cylinder tube 13, which has air guide plates 17 in its lower region , for deflecting the air sucked in by the gas inlet connector 14, which flows into the classifier cylinder 2 from below according to the arrows 18. This air is guided upwards in the counterflow classifier and first reaches an annular channel 19 of the lower cylindrical part 15 of the classifier cylinder 2 with the height h ₈ . This ring channel 19 is formed by the central tube 9, which projects into the cylindrical part 15 at a height h ₉ . The annular channel cross section results from the difference from the diameter d _{2 of} the cylinder section 15 minus the diameter d _{3 of} the central tube 9.

Above the height h ₈ or h ₉ , the lower cylindrical section 15 tapers over a first truncated cone 20 with the height h ₁₀ and a second truncated cone 21 with the height h ₁₁ to a second cylinder section 23 with the height h ₁₂ .

The air flow 18 drawn in in the lower part of the classifier cylinder 2 is consequently first compressed in the annular channel 19 to a smaller cross section (arrows 22) before it is further reduced in cross section via the two truncated cone sections 20, 21 and is thus greatly accelerated. This results in a strongly accelerated air flow in the annular channel 24 formed above the truncated cone 21, which serves as a separation gas stream 25. The two truncated cone sections 20, 21 therefore serve with their narrowing cross section to accelerate the separating gas flow 25. The annular channel 24 with the height h ₁₂ consequently forms a cylindrical section 23 with a diameter d ₄ , which is used as a line of sight or separating distance for the bulk material Conveying line 5 coming bulk material is used.

The cylindrical section 23 for forming the ring channel 24 ends just above the lower edge 26 of the bulk material conveying pipe 5, ie just above the mouth 26 of the bulk material flow in the classifier cylinder 2. This height difference is designated by h ₁₃ .

The cylindrical section 23 is followed by an expanding third truncated cone 27 with the height h ₁₄ , which acts as an accelerating diffuser and which in turn is followed by a cylindrical section 28 with the height h ₁₅ and a diameter d ₅ . The cylindrical section 28 has an upper end region 29 through which the opening 4 for the bulk material conveying pipe 5 is guided. Between the conveyor tube 5 and the cylindrical section 28, another ring channel 30 is formed, which opens laterally in a conveying material outlet connection 31.

Between the central tube 9 and the bulk material conveying tube 5, a narrow annular channel 32 is formed, which has a height h ₁₆ , ie it extends from the lower mouth 26 to the conical shoulder 33 of the conical tip 11.

With arrow 34 is the inflow direction of the diverting countercurrent classifier 1 supplied bulk material flow in the Bulk material delivery line specified. The arrow 35 shows the Supply of the amount of air sucked in or blown in is required as separation gas stream 25 for screening. The arrow 36 represents the outflow direction of the fines from the Conveyed goods outlet connection 31 represents that cleaned from the fines Coarse material falls through the line of sight in the counterflow classifier down and is schematic with arrow 37 in Fig. 1 shown.

The lower outlet 38 of the conical outlet funnel 12 is closed by an outlet aperture 39. It can also a cellular wheel sluice, not shown, is provided be. The decisive factor is the air flow of the supplied or sucked air through the counterflow classifier in vertical Direction.

The gas inlet connector 14 can also have a throttle element 40 to the transported in the countercurrent classifier To be able to regulate separation gas flow 25.

2 is the mouth region of the bulk material conveying pipe 5 in the sifter cylinder 2 in schematic Representation shown and explained in more detail below. Here the left half of the figure shows an arrangement according to the state the technology, while the right half of the figure Innovation according to the invention relates. For equal parts same reference numerals as indicated in Fig. 1 used. For simplified representation was made on the inclusion of the Truncated cone 27 waived. First, the left one Half of the figures in FIG. 2 explained as prior art:

The bulk material flowing into the bulk material conveying tube 5 is divided by the conical tip 11 of the central tube 9 and reaches the annular channel 32. The annular channel 32 is formed by the cylindrical outer surface 41 of the bulk material conveying tube 5 with the diameter, which is radially outer relative to the annular channel 32 d ₆ and the cylinder jacket surface 42 of the central tube 9 with the diameter d _3, which is located radially on the inside relative to the ring channel 32. This ring channel 32 forms an acceleration path for the bulk material flow supplied, ie the amount of air in the ring gap including the entrained solid particles is accelerated to a speed c, as is described in more detail in the “Process Engineering” reference to the deflection counterflow classifier. The speed profile 43 shown in FIG. 2, left half of the figure, is set, ie the parabolic speed profile on the lateral surfaces 41, 42 approaches zero. As a result, heavier solid particles 48 lying in the wall areas are not up to the maximum speed c _max . accelerated, but for example only to a speed c ₁ on the wall section 41 and c ₂ on the wall section 42, these speeds c ₁ , c ₂ not being sufficient to penetrate the separating gas stream 25 coming from below. Consequently, the coarse particles 48 falling in the edge region of the walls 41, 42 will not, contrary to their intended purpose, reach the countercurrent sifter downwards, but will reach the outer ring channel 30 as losses upwards for the removal of the fine material 49 (arrow 44). These losses of the coarse material 48 discharged with the fine material 49 are shown schematically by arrow 45.

Furthermore, the separating gas stream 25 coming from below also forms a speed profile 46, which is established in the annular channel 24 below the mouth 26. Here, too, the flow velocity V _{G of} the separation gas flow in the wall areas approaches zero, since the flow profile 46 drops sharply in the direction of the wall sections. The result of this is that there is only a slight upward flow of the separating gas flow 25 in the annular channel 24, in particular on the radially inner cylinder jacket surface 42, which is indicated by the speed arrow 47. The result of this is that in this near wall area of the radially inner cylinder jacket surface 42, fine material 49 falling down can penetrate the insufficiently present separating gas stream 25 there almost without hindrance and undesirably reaches the lower area of the counterflow classifier.

In order to counter this disadvantage, according to the illustration on the right in FIG. 2, both the radially outer lateral surface 41 and the radially inner lateral surface 42 are initially provided with a surface structure 50 in the annular channel 32, which leads to strong turbulence of the air flow in these wall areas. As a result, the speed profile 43 'is not designed to drop sharply towards the wall areas, but rather is designed in the manner of a rectangle with almost equally large speed vectors c also in the respective edge areas. The result of this is that the total quantity of conveying gas, including entrained solid particles, is brought to the required high speed in the acceleration section in the ring channel 32, so that the coarse material 48 also has the required speed c _max in the wall area. in order to penetrate the separating gas stream 25 directed from the bottom upwards. This means there is less loss of coarse material.

The wall section 42 of the central pipe 9 lying below the mouth 26 of the delivery pipe 5 also has a corresponding surface structure 50 ′, which corresponds to the surface structure 50 lying above it. This also results in a speed profile 46 ′ in the annular channel 24, which has a substantially steeper profile, in particular in the region of the radially inner wall section 42, which is generated by corresponding turbulence. As a result, a higher separation gas flow speed V _{GW is} present in this wall area, which prevents fine material 49 from falling. 2, on the right half of the figure, both a discharge of coarse material 48 with the fine material 49 into the ring channel 30 and a discharge of fine material 49 into the lower region of the classifier are avoided. This increases the effectiveness and efficiency of such a classifier considerably.

The surface structure 50, 50 'can be in the form of a zigzag Surface structure to be formed. The distance a between two adjacent tips 52, 52 'chosen so that this is generally smaller than the diameter D or the particle length of the solid particles forming the coarse material 48.

The surface structure 50 can also be made by other suitable ones Measures are roughened or formed so corresponding turbulence to generate turbulence arise. This can be done by hammering, for example formed surface with indentations in the form of spherical segments or a wave structure with a pointed wave crest or the like. Other swirl edges can also be used be provided.

The surface structuring 50 within the ring channel 32 preferably extends over a height section h ₁₇ which covers the entire acceleration distance, ie the entire ring channel 32. As a result, all particles are subjected to the acceleration required in order to achieve a desired final speed, even in the edge region.

In the ring channel 24 for the upward separating gas flow 25, a turbulence-generating surface structure 50 'on the radially inner wall section 42, ie on the outer cylindrical surface of the central tube 9, is essentially necessary, since this area is influenced by the flow of conveyed material from the ring channel 32 above. The height h _{18 of} the roughened surface structure 50 'for generating turbulence is therefore chosen in a similar order of magnitude as the height section h ₁₇ .

As can further be seen from the illustration in FIG. 1 the gas inlet connector 14 if possible in the lower region of the Circulating countercurrent classifier 1 arranged to a possible long distance for the ascending separation gas flow 18, 22, 25 to obtain. Furthermore, this route can be used to generate a Acceleration of this separation gas flow due to Diffuser effect can be used. After all, one long distance of the separation gas flow the effect of a Have indulgence of fines, d. H. Fines which the Separation path in the ring channel 24 has nevertheless penetrated in a lower section due to the ascending countercurrent can be detected.

1

Umlenk-Gegenstrom-Sichter

2

Sichterzylinder

3

Symmetrielängsachse

4

Öffnung

5

Schüttgut-Förderrohr

6

Umlenkflansch

7

Anschlußstutzen

8

Schüttgut-Zuführleitung

9

zentrales Rohr

10

kreuzförmige Befestigungsstege

11

kegelförmige Spitze

12

Auslaufsstutzen/trichter

13

Zylinderrohr

14

Gaseinsatzstutzen

15

Unterer Teil von 2

16

Ringkanal

17

Luftführungsbleche

18

Luft/Pfeil

19

Ringkanal

20

1. Kegelstumpf

21

2. Kegelstumpf

22

Pfeil/Luft

23

zylindrischer Abschnitt

24

Ringkanal

25

Trennungsstrom

26

Unterkante/Mündung

27

3. Kegelstumpf

28

zylindrischer Abschnitt

29

Abschlußbereich

30

Ringkanal

31

Fördergut-Auslaßstutzen

32

Ringkanal

33

Kegelansatz

34

Pfeil

35

Pfeil

36

Pfeil

37

Pfeil

38

Auslauf

39

Auslaufblende

40

Drosselorgan

41

radial außenliegende Mantelfläche

42

radial innenliegende Mantelfläche

43

Geschwindigkeitsprofil

44

Pfeil

45

Pfeil

46

Strömungsprofil

47

Geschwindigkeitsprofil

48

Grobgut

49

Feingut

50

Oberflächenstruktur

51

Pfeil

52

Spitze

The invention is not restricted to the exemplary embodiment described and illustrated. Rather, it also encompasses all professional further training within the framework of intellectual property rights claims.

1

Deflection-counterflow classifier

2nd

Classifier cylinder

3rd

Longitudinal axis of symmetry

4th

opening

5

Bulk conveying pipe

6

Deflection flange

7

Connecting piece

8th

Bulk feed line

9

central tube

10th

cross-shaped fastening webs

11

conical tip

12th

Discharge nozzle / funnel

13

Cylinder barrel

14

Gas insert

15

Lower part of 2

16

Ring channel

17th

Air guide plates

18th

Air / arrow

19th

Ring channel

20th

1. truncated cone

21

2. truncated cone

22

Arrow / air

23

cylindrical section

24th

Ring channel

25th

Separation current

26

Lower edge / mouth

27

3rd truncated cone

28

cylindrical section

29

Final area

30th

Ring channel

31

Conveyed goods outlet connection

32

Ring channel

33

Cone approach

34

arrow

35

arrow

36

arrow

37

arrow

38

Spout

39

Outlet cover

40

Throttle body

41

radially outer lateral surface

42

radially inner surface

43

Speed profile

44

arrow

45

arrow

46

Flow profile

47

Speed profile

48

Coarse

49

Fine goods

50

Surface structure

51

arrow

52

top

Claims (11)

1. A deflecting counter-current sifter with a cylindrical vertically orientated sifter cylinder (2) into the upper portion of which there is concentrically inserted a bulk goods conveyor pipe (5) which, at least in its lower mouth area (26), has an inner annular channel-like acceleration path (32) for the stream of bulk goods transported by a conveyor gas, whereby, directed in opposition to the stream of conveyor gas, there is an annularly channelled stream of separating gas which is directed from the bottom upwardly and which serves to break up the stream of bulk material into lighter and heavier constituents, the lighter constituents (49) being adapted to be transported upwardly and out of the sitting cylinder (2) through an annular passage (30) surrounding the bulk goods conveyor pipe (5), while heavier bulk goods parts (48) pass through the separating gas stream (25) and pass downwardly into the sifting cylinder (2), characterised in that at least the radially inner cylinder shell face (42) of the annular channel-like acceleration path (32) has at least in the lower mouth area (26) of the bulk goods conveyor pipe (5) and/or at least the radially inner cylinder shell surface (42) of the annular channel (24) conveying the separating gas stream (25) has in each case a surface structure (50, 50') which leads to increased turbulence and thus to an increase in the velocity of the respective air stream at the respective wall portion.
2. A deflecting counter-current sifter according to claim 1, characterised in that the radially inner (42) and radially outer (41) cylinder shell surfaces of the annular acceleration passage (32) in the bulk goods conveyor pipe (5) have a surface structure (50) in the form of a superficial roughening which leads to increase turbulence of the bulk goods conveyor gas in the wall area.
3. A deflecting counter-current sifter according to claim 1 or 2, characterised in that the annular acceleration passage (32) in the bulk goods conveyor pipe (5) and the annular channel-like flow path (24) for the separating gas stream (25) are formed by a central pipe (9), particularly with a conical tip (11), disposed centrally in the sifter cylinder (2).
4. A deflecting counter-current sifter according to claim 3, characterised in that at least in the area of the outlet (26) from the bulk goods conveyor pipe (5) into the sifter cylinder (2), the central pipe (9) comprises an upwardly and downwardly extending wall portion (42) of height h₁₇, h₁₈ and which has a surface structure (50, 50') for generating increased air flow turbulence and thus increased particle velocity.
5. A deflecting counter-current sifter according to one of the preceding claims, characterised in that in order to generate increased air flow turbulences, the surface structure (50, 50') is constructed as a zig-zag shaped superficial roughening, the distance a between two adjacent points (52, 52') being smaller than the greatest diameter D or particle length of the coarse fraction (48) of the material.
6. A deflecting counter-current sifter according to one of the preceding claims 1 to 5, characterised in that the surface structure is in cross-section constructed as an undulating structure, the crests of the undulations forming an acute angle.
7. A deflecting counter-current sitter according to one of the preceding claims, characterised in that the surface structure comprises swirling edges.
8. A deflecting counter-current sifter according to claim 1, characterised in that for forming a secondary sifting path the radial inlet aperture (14) for the separating gas stream (25) is disposed in the bottom part of the counter-current sifter.
9. A deflecting counter-current sifter according to one of the preceding claims, characterised in that the sifting cylinder (2) has in its lower part an outlet hopper (12) with upwardly continued cylinder portion (13) which laterally comprises a radially entering gas inlet connector (14) for the separating gas stream and in that the separating gas stream can be deflected into the sifting cylinder (2) by air baffles (17).
10. A deflecting counter-current sitter according to one of the preceding claims, characterised in that the conical outlet hopper (12) has an outlet orifice (38) which can be closed.
11. A deflecting counter-current sifter according to one of the preceding claims, characterised in that a throttle member (40) is associated with the gas inlet connector (14).

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