EP0517068B1 - Mixing kneader - Google Patents

Abstract

In a kneader mixer for carrying out mechanical, chemical and/or thermal processes, which has at least two axially parallel rotating shafts (5,6), there are to be provided, at least on the one shaft designated as the main shaft (5), disc faces (21) with kneading bars (25) arranged on their periphery. These will be swept by cleaning or kneading and conveying elements (7), which are arranged on the other shaft designated as the stripping shaft (6). In this arrangement, the kneading bars (25) of two adjacent disc faces (21) on the main shaft (5) are to maintain a gap (a) between each other, through which the cleaning or kneading and conveying element on the stripping shaft (6) passes. <IMAGE>

Description

The invention relates to a mixer kneader for carrying out mechanical, chemical and / or thermal processes with at least two axially parallel rotating shafts, disk surfaces with kneading bars arranged on their periphery being provided on the one shaft referred to as main shaft, which are coated by kneading bars which are on disk surfaces are arranged on the other shaft referred to as the cleaning shaft, the kneading bars of two adjacent disk surfaces on the main shaft or on the cleaning shaft maintaining a distance from one another through which the disk surface with the kneading bar on the cleaning shaft or the main shaft passes.

Such a multi-spindle mixing and kneading machine is known, for example, from CH-A-506 322. One of the shafts is provided with radial disk elements and axially aligned kneading bars arranged between the disks and is referred to as a disk shaft. Kneading elements shaped like frames engage between these disks and are arranged on the second parallel stirrer shaft. These kneading elements clean the discs and kneading bars of the disc shaft.

In order to achieve a reasonably sufficient cleaning of the disc surfaces, the agitator shaft must rotate faster than the disc shaft by an intended speed ratio. This speed ratio depends primarily on the number of kneading bars on the disc elements, since the kneading elements have to intervene in the spaces between the kneading bars. This results in an insufficient cleaning effect of the pane surfaces, which in turn has a negative effect on the heat transfer to the product to be treated.

The same applies to a device according to DE-A-20 12 294, EP-A-0 144 092 and CH-A-565 585.

From FR-A 1 197 720, star-shaped or cross-shaped elements are placed on two shafts rotating in the same direction and have axially extending rods on their outer circumference. These elements can only be used for stirring, but no mixing or kneading effect can be achieved.

A mixing device is known from Patent Abstracts of Japan, vol. 13, no. 29 (C562) 3377, January 23, 1989, in which elliptical disk elements are seated on two adjacent shafts which carry bars at their outer ends. With these elliptical disk elements, there is only a small area for heat transfer.

A mixer kneader of the type mentioned at the outset is known from EP-A-0 460 466 with the filing date 24.05.91, the priority date 05.06.90 and the publication date 11.12.91. There are circular discs placed on two adjacent shafts, which carry kneading bars distributed over their circumference. Since both shafts rotate at the same speed, cleaning problems arise similar to those with the mixer kneader according to CH-A-506 322. Large areas of the disk surfaces are not cleaned.

The present invention has for its object to significantly improve the cleaning of all areas and parts within the mixing kneader and at the same time the kneading effect exerted on the product. In the case of thermal treatment of the product, there is also the task that the heat exchanger area within the mixing kneader is increased and the heat transfer to the product is significantly improved.

To achieve this object, wings are formed on both sides of the kneading bar, which run radially at a short distance from the disk surfaces of the main shaft or cleaning shaft, and that the disk surfaces of at least the main shaft are sawtooth-like on their outer circumference or are provided with wavy indentations.

In contrast to the prior art, it is no longer necessary to take into account a continuous kneading bar, so that areas of the disk surfaces or the main shaft can also be cleaned that were previously not accessible to the cleaning element. The cleaning shaft is also cleaned by the kneading bars on the disc elements of the main shaft. For this reason, it is possible to heat the disk surfaces of the cleaning shaft in a thermal process, since the heat exchange surface of the cleaning shaft is also cleaned here and caking is thus avoided.

If wings are now formed on the kneading bars which extend radially at a short distance between the main or cleaning shaft and the kneading bar, the disk surfaces on the main shaft and the cleaning shaft are almost completely cleaned. It is therefore advisable to also design these disc surfaces to be heatable, so that the heat transfer surfaces are increased again. It goes without saying that A large number of kneading gaps are formed both between the blades and the kneading bars and also the inner wall of the mixing kneader, by means of which the kneading of the product in the mixing kneader according to the invention is substantially improved.

If a faster transport of the product is desired, the disk surfaces are sawtooth-shaped, or they have wavy bulges.

It should not go unmentioned that the carrier for the kneading bars on the cleaning shaft does not necessarily have to be designed as a disk surface. Depending on the customer's requirements, the kneading bar and cleaning shaft could also be connected by a simple stem that can slide through the above-mentioned distance of the kneading bars of two adjacent disc elements on the main shaft. In many cases, however, pane surfaces are preferable because they contribute to increasing the heat exchange and improving the kneading effect.

The distance between the kneading bars of adjacent disk elements of the main shaft in turn causes the disk surfaces of the cleaning shaft or an above-mentioned stem to be in gap with the disk surfaces of the main shaft. Even the disk surfaces or the stem are preferably arranged centrally between two disk surfaces of the main shaft. It goes without saying that if the kneading bars of the main shaft and cleaning shaft are preferably identical, not only are two adjacent kneading bars of the main shaft spaced apart, but this distance is also formed by two adjacent kneading bars of the cleaning shaft, but offset, by which then the Disc surface of the main shaft strokes.

While the kneading bars are preferably of identical design, this can also apply to the disc surfaces of the main shaft and cleaning shaft, but they can also be designed differently, depending on the user's request, so that product transport through the cleaning shaft is different from that through the main shaft. The invention leaves many possibilities open here.

In one embodiment of the invention, the main shaft and cleaning shaft rotate in the same clockwise direction. However, the disc or cleaning elements according to the invention also allow the main shaft and Cleaning wave in the counterclockwise direction. It is also possible to rotate the main shaft and cleaning shaft at the same or different speeds. When rotating, whether in the same direction or in opposite directions, at the same speed, the number of kneading bars on the main shaft should correspond to that on the cleaning shaft. This enables the most economical cleaning for this speed without interfering with the kneading bars.

On the other hand, if the main shaft and cleaning shaft rotate at different speeds, the number of kneading bars arranged on the main shaft and on the cleaning shaft should be inversely proportional to the speed ratio. For example, if the speed ratio of the main shaft to the cleaning shaft is 1: 4, then four kneading bars are arranged on the main shaft and only one kneading bar on the cleaning shaft. Eight kneading bars can also be provided on the main shaft and two kneading bars on the cleaning shaft.

If the speed ratio is odd, for example 1: 1.25, five kneading bars are arranged on the main shaft and four kneading bars on the cleaning shaft.

In summary, it must be emphasized that the present mixer kneader is extremely flexible. the arrangement of the shaft elements, the number of kneading bars and the speed ratio allowed. The main advantages are improved self-cleaning, a larger specific heat exchange surface, a more effective one Surface renewal with diffusion-determined evaporation processes, a more intensive mixing effect with gentle kneading and less compacting as well as a narrow residence time spectrum.

Fig. 1

eine Draufsicht auf einen erfindungsgemässen Mischkneter mit einem teilweise aufgeschnittenen Gehäuse;

Fig. 2

eine Draufsicht auf einen Ausschnitt von zwei zusammenwirkenden Wellen;

Fig. 3

eine Draufsicht auf einen Ausschnitt einer Abwicklung der einen Welle gem. Fig.2;

Fig. 4

eine Draufsicht auf einen Ausschnitt einer Abwicklung der anderen Welle gem. Fig. 2;

Fig. 5

einen Querschnitt durch die beiden Wellen gem. Fig. 2 entlang Linie V - V;

Fig. 6 und 7

Querschnitte durch weitere Ausführungsbeispiele von Wellen entsprechend Fig. 5;

Fig. 8

einen Querschnitt durch eine Hauptwelle mit schraffiert angedeuteter Darstellung von nicht gereinigten Flächen auf Scheibenelementen nach der CH - PS 506 322;

Fig. 9

einen Querschnitt durch eine Hauptwelle mit schraffiert angedeuteten nicht gereinigten Flächen entsprechend der vorliegenden Erfindung;

Fig. 10

eine Draufsicht auf einen Ausschnitt aus einem weiteren Ausführungsbeispiel eines erfindungsgemässen Mischkneters im Bereich von zwei zusammenwirkenden Wellen;

Fig. 11

eine Draufsicht auf einen Ausschnitt einer Abwicklung der einen Welle aus Fig. 10;

Fig. 12

eine Draufsicht auf einen Ausschnitt einer Abwicklung der anderen Welle gem. Fig. 10;

Fig. 13 und 14

schematisch dargestellte Querschnitte durch die beiden Wellen gem. Fig. 10 entlang Linie XIV - XIV;

Fig. 15

eine Draufsicht auf einen Ausschnitt eines weiteren Ausführungsbeispiels eines Mischkneters im Bereich von zwei zusammenwirkenden Wellen;

Fig. 16

eine Draufsicht auf einen Ausschnitt aus einer Abwicklung der einen Welle nach Fig. 16;

Fig. 17

eine Draufsicht auf einen Ausschnitt aus der Abwicklung der anderen Welle gem. Fig. 16;

Fig. 18 und 19

Querschnitte durch die beiden Wellen entlang Linie XX - XX in Fig. 16.

Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and from the drawing; this shows in

Fig. 1

a plan view of an inventive mixer kneader with a partially cut housing;

Fig. 2

a plan view of a section of two interacting shafts;

Fig. 3

a plan view of a section of a settlement of a wave acc. Fig.2;

Fig. 4

a plan view of a section of a settlement of the other wave acc. Fig. 2;

Fig. 5

a cross section through the two waves acc. 2 along line V - V;

6 and 7

Cross sections through further embodiments of waves according to Fig. 5;

Fig. 8

a cross section through a main shaft with hatched representation of not cleaned surfaces on disc elements according to CH - PS 506 322;

Fig. 9

a cross section through a main shaft with hatched, not cleaned surfaces according to the present invention;

Fig. 10

a plan view of a section of a further embodiment of a mixer kneader according to the invention in the region of two interacting shafts;

Fig. 11

a plan view of a section of a development of the one shaft from FIG. 10;

Fig. 12

a plan view of a section of a settlement of the other wave acc. Fig. 10;

13 and 14

schematically illustrated cross sections through the two waves acc. 10 along line XIV - XIV;

Fig. 15

a plan view of a section of a further embodiment of a mixer kneader in the region of two interacting shafts;

Fig. 16

a plan view of a section of a development of the one shaft of FIG. 16;

Fig. 17

a plan view of a section of the development of the other wave acc. Fig. 16;

18 and 19

Cross sections through the two waves along line XX - XX in FIG. 16.

A mixer kneader P has gem. Fig. 1, a housing 1, which consists of several housing sections 1 a, 1 b and 1 c. The housing sections are coupled to one another by corresponding flange connections 2. In the housing section 1 a there is a feed nozzle 3 for a product to be treated in the mixing kneader and in the housing section 1 c an outlet nozzle 4 for the treated product.

The product is transported from the feed nozzle 3 to the outlet nozzle 4 by means of two shafts 5 and 6 and kneading and transport elements 7 arranged thereon. During transportation, the product is mixed and kneaded, and preferably a thermal treatment takes place. For this purpose, the shafts 5 and 6 and optionally also the kneading and transport elements 7 and, not shown in more detail, the housing wall 8 are heated. For insertion of a heating medium in the shafts 5 and 6 and from there optionally into the interior of the kneading and transport elements 7, connections 9 and 10 are provided, these connections 9 and 10 around corresponding outlet nipples 11 and 12 for the heating medium guided through the shafts 5 and 6 are arranged. Appropriate routing of the heating medium in the lateral surfaces of the shafts 5 and 6 and a corresponding return through the outlet nipples 11 and 12 are prior art and are therefore not described further.

Between the connections 9 and 10, shaft lugs 13 and 14 connected to the shafts 5 and 6 pass through a lantern 15, a stuffing box 16 and 17 being provided against the housing 1 for sealing the shafts 5 and 6, respectively. The shaft journals 13 and 14 are coupled to one another outside the lantern via corresponding gear elements 17 and 18, for example gear wheels, the gear element 17 being connected to a drive 20 via a gear 19. Via this drive 20 and the gear 19, at least the gear element 17 is rotated, which is transmitted to the shaft 5. This rotary movement can be transmitted to the gear element 18 in the same or opposite directions and at the same or different speed. Corresponding transmission gears are customary in the trade and should not be described in more detail here.

The design of the kneading and transport elements 7 and their are essential within the scope of the present invention Arrangement on shafts 5 and 6. For the sake of clarity, shaft 5 is also referred to below as the main shaft and shaft 6 as the cleaning shaft. Kneading and transport elements 7 are placed on each shaft 5 and 6, which have disc surfaces 21 as the basis for the respective shaft 5 and 6. Various exemplary embodiments of disk surfaces 21 are shown in FIGS. 5 to 7.

A sawtooth-like disc surface 21 b according to FIG. FIG. 5. It is shown in FIG. 6 that the disc surfaces 21c on the cleaning shaft 6 are only designed as wings, while disc surfaces 21d according to FIG. 7 have recesses 22 through which the product to be processed can be transported.

A further variant of a disk surface 21 e can be found in FIGS. 13 and 14 and 18 and 19. There, a disk surface circumference 23 is no longer circular, but has wavy indentations 24.

Since preferably the kneading and transport elements 7 on the main shaft 5 as well as on the cleaning shaft 6 are identical except for the configuration of the disk surfaces 21, they should be provided with the same reference numbers below. Of course, this leaves open within the scope of the present invention that the kneading and transport elements 7 on the main shaft 5 are configured differently than those on the cleaning shaft 6.

It is essential that both the main shaft 5 and, if a disk surface 21 is provided, the cleaning shaft 6, kneading bars 25, which are U-shaped, are located on the disk surface circumference 23. In other words, an actual support leg 26 sits on the disk surface circumference 23, while wings 27 and 28 protrude from this support leg 26 on both sides of the respective shaft 5 or 6. This then results in a kneading and transport element 7, as shown in particular in FIG. 2, which has a T-shaped configuration when viewed from above.

It is also essential that two adjacent kneading and transport elements 7 or their adjacent vanes 27 maintain a distance a from one another, which allows a disk surface 21 of the opposite shaft 5 or 6 to pass through it. Accordingly, this distance a is slightly larger than the thickness d of a disk surface 21.

Furthermore, the disk surfaces 21 of the main shaft 5 and cleaning shaft 6 are arranged offset to one another. This offset is preferably such that a disk surface 21 of the cleaning shaft 6 engages approximately centrally between two disk surfaces 21 of the main shaft 5. However, this offset can also occur off-center, in which case knee spaces 29 of different widths then arise. However, the design of identical knee spaces 29 is preferred.

3 and 4 it can be seen that the kneading bars 25 are inclined in relation to the axial direction of the shafts 5 and 6, respectively. This improves the transport effect. Furthermore, arrows 30 and 31 indicate that the main shaft and cleaning shaft rotate in opposite directions.

5 to 7, the interaction of the kneading and transport elements of the main shaft 5 and cleaning shaft 6 is shown. In this case, an opposite movement of main shaft 5 to cleaning shaft 6 takes place in a ratio of 1: 4, ie the cleaning shaft 6 rotates four times as fast as the main shaft 5. This results in eight kneading bars on the main shaft or the disk surfaces 21 b arranged there 25 are provided, while on the disc surfaces 21 ad the cleaning shaft 6 two kneading bars are sufficient, which are diametrically opposite. Here, it would also be possible to arrange only one kneading bar on the disk surfaces of the cleaning shaft, while four kneading bars are provided on the disk surfaces of the main shaft. This means that the number of kneading bars on the disc surfaces of the cleaning shaft is normally the same as the kneading bars on the Disc areas of the main shaft in the inverse ratio of the speeds of both shafts. However, since the traces of the main shaft's kneading bars on the cleaning shaft can be identical, the number of kneading bars on the main shaft can also be reduced, if desired.

The advantageous cleaning effect of the present invention compared to, for example, CH-PS 506 322 can be clearly seen when comparing FIGS. 8 and 9. In Fig. 8, hatched, not cleaned surfaces 32 are still present on a disk surface 21 to a relatively large extent. 9, on the other hand, it can be seen that there are no more contiguous, uncleaned surfaces, but that only certain areas 32 a near the main shaft 5 and certain areas 32 b around the kneading bars 25 have not been cleaned. The areas which have not been cleaned are thus so minimal that the heat exchange between the disk surface 21 and the product to be treated is improved to a very excellent degree.

The exemplary embodiments in FIGS. 10 to 14 differ from those just described in that the main shaft 5 is synchronized with the cleaning shaft 6. This is shown by the two arrows 30 a and 30 b. Furthermore, both shafts 5 and 6 run at the same speed, so that the number of kneading bars 25 arranged on the disk surfaces 21 is also the same. Only the disk surfaces 21 are on the two Shafts 5 and 6 are offset from each other or stand on a gap.

The wavy indentations 24 in the disc surfaces 21 e acc. 13 and 14 allow faster product transport or faster passage of gases or vapors.

Of course, a non-integer division is also possible, for example if the speed ratio of main shaft 5 to cleaning shaft 6 is 1: 1.25. In this case, five kneading bars 25 are then arranged on the main shaft, as shown in FIGS. 15 to 19, while only four kneading bars are symmetrically distributed on the disk surfaces 21 of the cleaning shaft 6. Thus, the present invention allows an extraordinary variety of speed ratios and number of kneading bars on each disc surface.

Claims (11)

1. Mixing kneader for carrying out mechanical, chemical and/or thermal processes, having at least two rotating shafts (5, 6) with their axes parallel, disk surfaces (21) with kneading bars (25) arranged on their periphery being provided on the one shaft designated as the main shaft (5), which are swept by kneading bars (25) arranged on disk surfaces (21) on the other shaft designated as the stripping shaft (6), the kneading bars (25) of two neighbouring disk surfaces (21) on the main shaft (5) or on the cleaning shaft (6) maintaining mutual spacing (a) through which passes the disk surface (21) with the kneading bar (25) on the stripping shaft (6) or the main shaft (5), characterised in that wings (27) which extend radially at a small distance from the disk surfaces (21) of the main shaft (5) or stripping shaft (6) are moulded to the both sides of the kneading bar (25) and in that the disk surfaces (21b, 21e) at least of the main shaft (5) are formed in the manner of sawteeth or are provided with wavy indentations (24) on their external periphery.
2. Mixing kneader according to claim 1, characterised in that the kneading bars (25) of the main shaft (5) and of the stripping shaft (6) are of identical design.
3. Mixing kneader according to claim 1 or 2, characterised in that the disk surfaces (21) of the main shaft (5) and stripping shaft (6) are of different design.
4. Mixing kneader according to one of claims 1 to 3, characterised in that the main shaft (5) and stripping shaft (6) rotate in the same clockwise direction.
5. Mixing kneader according to one of claims 1 to 3, characterised in that the main shaft (5) and stripping shaft (6) rotate in opposite directions.
6. Mixing kneader according to claim 4 or 5, characterised in that main shaft (5) and stripping shaft (6) rotate at the same speed of rotation.
7. Mixing kneader according to claim 6, characterised in that the number of kneading bars (25) on the main shaft (5) corresponds to that on the stripping shaft (6).
8. Mixing kneader according to claim 4 or 5, characterised in that the main shaft (5) and the stripping shaft (6) rotate at different speeds of rotation.
9. Mixing kneader according to claim 8, characterised in that the number of the kneading bars fitted to the main shaft (5) and to the stripping shaft (6) is inversely proportional to the ratio of the speeds of rotation.
10. Mixing kneader according to claim 9, characterised in that kneading bars (25) which leave the same track on the other shaft (5, 6) in each case, have been removed.
11. Mixing kneader according to at least one of claims 1 to 10, characterised in that the disk surfaces (21) of the main shaft (5) and stripping shaft (6) can be heated, as can the main shaft (5) and the stripping shaft (6) themselves.

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