EP2992960B1 - Device for grinding dispensed products with prior screening - Google Patents

Description

The invention relates to a device through which air flows for shredding pourable feed material according to the preamble of patent claim 1.

Such devices belong to the field of mechanical process engineering and are used to comminute bulk materials such as minerals, pharmaceutical and chemical substances, food, cellulose-containing materials, plastics and the like. Characteristic of such devices is an air flow generated by the rotor, the so-called own air, which takes over the transport of the feed material into and out of the shredding device and also causes the cooling of the feed material and the shredding tools. In addition, the inherent air, depending on its flow speed, determines the residence time of the feed material in the shredding area and thus the intensity of the shredding. Precisely maintaining the machine-specific air volume when operating generic devices is therefore of great importance in order to produce a high-quality end product.

In order to prevent devices from being damaged by foreign bodies in the feed material, it is also known to provide a heavy material classifier in the area of the material feed. Due to a strong change in direction of the material flow in the inlet to the shredding device, foreign particles are separated from the material flow due to their inertia, with the separation limit being predetermined by the speed of the material flow. In order to maintain a predetermined separation limit, it is therefore necessary to apply a constant feed rate to the heavy goods classifier.

What proves to be problematic is that, as a rule, the air volume of a shredding device is many times larger than the air volume of the upstream classifier. If a shredding device is operated with the optimal amount of air for it, this leads to speeds in the material flow in the area of the visible passage, at which usable feed material is undesirably separated from the material flow. To counteract this is therefore off the DE 43 16 350 C1 a gas-flowing shredding machine is known, which is preceded by a feed device with a viewing passage, with additional air being supplied in the area of the viewing passage using a blower.

Another such shredding device is from US1272311 known.

It is the object of the present invention to further improve shredding devices with an upstream pneumatic viewing passage.

This task is solved by a device with the features of patent claim 1.

Advantageous embodiments result from the subclaims.

With the invention, it is possible for the first time to meet the conflicting requirements for an optimal amount of air for the shredding device on the one hand and an optimal amount of air for the feed device on the other hand, without having to accept any qualitative or economic losses. Thanks to the invention, the feed material is processed under optimal process conditions both during screening and comminution. This allows for reliable and precise separation of foreign particles from the gas-solid mixture when sifting heavy goods and, when comminuting the feed material, compliance with the optimal process parameters for the respective type of comminution, such as the residence time of the feed material in the shredding zone, temperature of the feed material and the comminution tools and the like , which ultimately enables the economical production of a high-quality end product.

According to the invention, the inlet opening for supplying secondary air opens directly into the comminution chamber. On the one hand, this allows a simple and economical construction of devices according to the invention. At the same time, the introduction of the secondary air far downstream of the visible passage prevents an unwanted influence of the secondary air on the processes in the visible passage, which would impair precise compliance with the separation limit.

In another embodiment, the inlet openings for supplying secondary air open into the second channel section of the supply device The advantage is that the secondary air and the gas-solid mixture mix extensively and thus create uniform conditions for the shredding process.

Preferably, the secondary air is distributed evenly over the circumference of the feed channel opening into the shredding device using an annular channel in order to uniformly act on the entire cross section of the feed channel. The secondary air from the annular channel can either flow directly into the comminution chamber of the comminution device or indirectly via openings to the feed channel, which then leads into the comminution chamber.

In order to be able to adapt to the feed material and the type of comminution device on the one hand, but also to optimize the processing during the ongoing comminution operation, on the other hand, the secondary air quantity can be regulated in an advantageous development of the invention. For this purpose, a regulating element is advantageously provided, for example directly on the inlet opening or on the annular channel.

It also proves to be advantageous to provide further openings for supplying air in the rear wall of the shredding device. The secondary air can be supplemented via these openings, so that the amount of secondary air to be introduced in the area of the supply device can be lower. At the same time, additional air in the area of the rear wall achieves more uniform cooling of the shredding device.

With the invention it was found that very good results can be achieved if the amount of secondary air is 10% to 50% of the amount of air, preferably 15% to 35%, most preferably 25%.

The invention is explained in more detail below using an exemplary embodiment shown in the drawings, with further features and advantages of the invention becoming apparent. Identical reference symbols are used for identical and functionally identical features of different embodiments, as long as this serves to provide a better understanding of the invention.

Fig. 1

einen Vertikalschnitt durch eine erste Ausführungsform einer erfindungsgemäßen Vorrichtung,

Fig. 2

einen Querschnitt durch die in Fig. 1 dargestellte Vorrichtung entlang der dortigen Linie 11 -11,

Fig. 3

einen Vertikalschnitt durch eine zweite Ausführungsform einer Vorrichtung, und

Fig. 4

einen Vertikalschnitt durch eine dritte Ausführungsform einer Vorrichtung.

It shows

Fig. 1

a vertical section through a first embodiment of a device according to the invention,

Fig. 2

a cross section through the in Fig. 1 Device shown along line 11 -11 there,

Fig. 3

a vertical section through a second embodiment of a device, and

Fig. 4

a vertical section through a third embodiment of a device.

The Fig. 1 and 2 show a comminution device 1 according to the invention in the form of an impact plate mill. The shredding device 1 has a substantially cylindrical housing 2, which is firmly connected to the ground via a foot 3. The housing 2 encloses a first chamber 5, in which the comminution work is carried out, and a second chamber 6, which serves to generate an air flow and to discharge the material. The two chambers 5 and 6 are arranged one after the other with respect to the housing axis 4 and are connected to one another via an opening 7 concentric to the axis 4. The front of the housing 2 is closed by a front wall 8 and a rear wall 9. The rear wall 9 has a concentric opening in the area of the axis 4, into which a horizontal shaft bearing 10 is inserted for rotatably receiving a rotor 11. The rotor 11 is composed of a shaft 12 coaxial with the axis 4, the end of which lies outside the housing 2 carries a multi-groove disk 13 for force coupling with a drive. The end of the shaft 12 located in the housing 2 extends through the two chambers 5 and 6, the shaft section located in the first chamber 5 carrying a beater wheel 14. The beater wheel 14 essentially consists of a hub 15, to which a baffle plate 16 and radial webs 17 are connected radially outwards. At the ends of the webs 17 forming the rotor circumference, comminution tools in the form of impact plates 18 are attached. The effective edges of all striking plates 18 lie on a common flight circle, which is opposite an impact path 19 formed by the inner circumference of the first chamber 5 while maintaining a radial working gap.

The rotor 11 further comprises a fan wheel 20, which also sits on the shaft 12 in a rotationally fixed manner with a hub 21 and extends obliquely outwards into the second chamber 6 with a conical plate 22. In the outer peripheral area of the cone plate 22, radially aligned air blades 23 are arranged at a uniform circumferential distance, which generate the air of the shredding device 1 during operation of the rotor 11. The sufficiently comminuted material is withdrawn via a material discharge 24, which opens tangentially from the second chamber 6.

To load the shredding device 1 with feed material, the front wall 8 has a central opening 25 axially opposite the shaft 12, to which a feed device 30 with an integrated heavy material classifier is connected. The feed device 30 has a feed channel 31 with a chute-like first channel section 32 and an adjoining angled second channel section 33, which opens into the first chamber 5 of the shredding device 1. In the area of the first channel section 32, flow guide bodies 26 are arranged on the inside, which help determine the flow path. The feed channel 31 undergoes a change in direction of approximately 180° in the transition area from the first channel section 32 to the second channel section 33, which results in a reversal of direction of the material flow. The supply channel 31 is provided with an opening 34 in the outer circumference of the deflection area. This area thus forms a viewing passage 35, in which heavier particles in the feed material do not follow the reversal of direction of the remaining material flow due to their weight and the associated inertia, but are separated from the feed material via the opening 34 due to effective gravitational forces.

The longitudinal section of the second channel section 33 located directly in front of the loading opening 25 is surrounded by an annular channel 36, which is supplied with secondary air 40 via a pipe socket 37 which opens radially. To control the amount of air, the flow cross section of the pipe socket 37 can be adjusted using a flap 38. The side of the annular channel 36 facing the comminution device 1 is open, so that the secondary air, which is distributed evenly over the circumference of the second channel section 33 in the annular channel 36, enters axially into the first chamber 5 of the comminution device 1 and mixes there with the gas-solid mixture from the supply channel 31.

During operation of a device 1 according to the invention, the gas-solid mixture 27 is fed via the first channel section 32 to the viewing passage 35 at an optimal speed and optimal mixing ratio for heavy goods sifting. Foreign bodies in the feed material are eliminated in the area of the viewing passage 35 by redirecting the material flow via the opening 34. The feed material finally reaches the first chamber 5 of the shredding device 1 via the second channel section 33 of the feed channel 31.

The air required for optimal comminution of the feed material is sucked in by the fan wheel 20 of the comminution device 1, the amount of air required being considerably larger than that provided by the gas-solid mixture 27. In order to still supply the shredding device 1 with sufficient air without reducing the efficiency of the heavy material classifier, the difference in air quantity is introduced as secondary air 40 into the first chamber 5 of the shredding device 1 via the pipe socket 37 and the annular channel 36. In this way, it is possible to operate both the heavy material classifier in the area of the feed device 30 and the shredding device 1 while maintaining optimal process parameters.

In the Figure 3 The shredding device 1 shown corresponds largely to that shown below Figures 1 and 2 described, so that to avoid repetition and using the same reference numbers, reference is made to what was said there. In contrast to the previously described embodiment, the secondary air 40 in the shredding device 1 according to Figure 3 not directly from the annular channel 36 'into the shredding device 1, but indirectly via the second channel section 33' of the feed device 30. For this purpose, the annular channel 36' is closed on all sides, with the second channel section 33' in the area enclosed by the annular channel 36' Openings 39 at a uniform circumferential distance, for example 2, 3 or 4 openings 39. The secondary air 40 thus flows from the annular channel 36 'through the openings 39 radially in the second channel section 33' of the supply channel 31 and already mixes there with the gas-solid mixture 27.

Fig. 4 shows an embodiment of the invention in which the comminution device 1 is embodied by a eddy current mill. The eddy current mill has a cylindrical housing 42 which encloses a comminution chamber 43. The housing 42 is surrounded on the circumference by a housing jacket 44, which forms a Good discharge 45 is open at the bottom. The housing 42 serves to accommodate a rotor 46, which is rotatably mounted within a shaft bearing 47 inserted centrally into the rear wall 45. The shaft 48 of the rotor 46 carries, with its end lying outside the housing 42, a multi-groove disk, via which the rotor 46 is driven. On the opposite end of the shaft 48 sits a beater wheel 49, which is formed by a hub cone 50 sitting coaxially on the shaft 48 and a carrier disk 51 and a plane-parallel ring disk 52, which accommodate axially aligned striking plates 53 on their outer circumference.

A central baffle track 54 lies opposite the impact plates 53 while maintaining a grinding gap, to which a screen track 55 is connected on both sides in the axial direction. The sieve tracks 55 are offset from the housing jacket 44 in the radial direction and in this way each form an annular channel 56 through which the sufficiently fine material is drawn off and fed to the material discharge 45.

An opening 57 concentric to the axis of rotation is arranged in the front wall 44, to which the feed device 30 connects. The feed device 30 essentially corresponds to that below Fig. 1 to 3 described, so that what is said there applies to the same characteristics. The feed device 30 therefore comprises a feed channel 31 with a first channel section 32 and a second channel section 33, which are separated from one another via a viewing passage 35. The second channel section 33 adjoins the opening 57 in the front wall 44 of the device 1 according to the invention.

To feed in secondary air 40, an opening 58 is provided in the second channel section 33 of the supply channel 31 immediately in front of the opening 57. Outside the second channel section 33, the opening 58 is surrounded by an air shaft 59, which is formed by the front wall 44 and the opposite second channel section of the feed device 30 as well as two plane-parallel, spaced-apart side plates 59, which connect the front wall 44 to the feed device 30 . A pivoting flap 60 is inserted into the ventilation duct 59, with which the amount of secondary air 40 can be regulated.

During operation, the eddy current mill generates an air flow (own air) with the impact plates 53 and the air blades 23 on the impact wheel 49, which represents the drive for the material flow through the mill. The eddy current mill thus sucks the feed material 27 through Feeding device 30, where unsuitable feed material is separated out in the area of the viewing passage 35. Via the opening 57, the screened feed material then reaches the impact plates 53 and the impact track 54 via a disk-shaped channel between the carrier disk 51 and the annular disk 52, from where, after sufficient comminution, it reaches the side sieve paths 55 and there via the annular channels 56 and the Good discharge 45 is passed from the eddy current mill.

Since the specific amount of air in the eddy current mill is significantly larger than that required in the area of the heavy material classifier, secondary air 40 is introduced into the eddy current mill via the ventilation duct 59 and the opening 58. In addition, air can be led into the comminution chamber 5 through openings 61 on the rear wall 45 of the eddy current mill in order to supply the eddy current mill with sufficient air.

Claims (7)

1. Device for the comminution of pourable feed material, comprising a housing (2) enclosing a comminution chamber (5) in which a rotor (11) rotating around an axis (4) is arranged and shows on its circumference comminution tools (18), and comprising a feeding system (30), that conveys the feed material as a gas-solids mixture into the comminution chamber (5), wherein the feeding system (30) shows a pneumatic sifting passage (35) to separate out foreign matter from the feed material by gravity, wherein the device (1) shows at least one inlet opening (25) for supplying secondary air that opens into in the gas-solids mixture downstream from the sifting passage (35), characterized in that the at least one inlet opening (25) opens directly into the comminution chamber (5).
2. Device according to claim 1, characterised in that the feeding system (30) has a feeding channel (31) with a first channel section (32) arranged upstream from the sifting passage (35) and a second channel section (33') arranged downstream form the sifting passage (35) and leading to the comminution chamber (5) and in that the at least one inlet opening (25, 39) is fed from an annular channel (36) surrounding the second channel section (33, 33') of the feeding system (30).
3. Device according to claim 2, characterised in that the annular channel (36) is open on the side facing the housing (2) and is adjacent to the inlet opening (25).
4. Device according to one of the claims 1 to 3, characterised by a regulating organ (38) for the control of the quantity of secondary air.
5. Device according to claim 4, characterised in that the regulating organ (38) is arranged on the annular channel (36, 36').
6. Device according to one of the claims 1 to 5, characterised in that the quantity of secondary air amounts to 10% to 50% of the air flow rate, preferably 15% to 35%, most preferably to 25%.
7. Device according to one of the claims 1 to 6, characterised in that the device (1) shows in the area of the rear wall (45) at least one opening (61) for the supply of air.

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