EP2217388A1

EP2217388A1 - Screen system with tube-shaped screen and method for operating a screen system with tube-shaped screen

Info

Publication number: EP2217388A1
Application number: EP08857543A
Authority: EP
Inventors: Jürgen KISING
Original assignee: Artech Systems AG
Current assignee: Artech Systems AG
Priority date: 2007-12-05
Filing date: 2008-11-25
Publication date: 2010-08-18
Anticipated expiration: 2028-11-25
Also published as: CA2708019A1; DE202008017901U1; KR20100106991A; US8453845B2; US20100258482A1; WO2009071221A1; DK2217388T3; JP2011505245A; EP2067534A1; ATE529196T1; CA2708019C; CN101925415B; AU2008333606B2; KR101393148B1; ES2376029T3; JP5582536B2; CN101925415A; EP2217388B1; AU2008333606A1

Abstract

The system (3) has a tube or screen frame (31), which is subjected to ultrasound stimulation by an ultrasound converter (13) and a feed pipe sound converter (34). The converter (34) is designed such that amplitude of the stimulation comprises components in a vertical direction to a middle axis of a tube-like screen, and components in a parallel direction to the middle axis of the tube-like screen. The amplitude is transferred to a tube or to the screen frame. The feed pipe sound converter comprises a curved region with a curvature angle of maximum of 90 degrees. An independent claim is also included for a method for operating a screening system.

Description

Sieve system with a tubular sieve and method for operating a sieve system with a tubular sieve

The invention relates to a screening system according to the preamble of claim 1 and a method for operating a screening system according to the preamble of claim 13.

In industry, there are a variety of applications where it is desirable to achieve size classification of a material and / or to avoid particle agglomeration or, if it has already occurred, to break it up.

For this purpose, generally known screening machines are used which use screen systems which differ in particular by the design and orientation of the screens used. Conventional vibratory and tumble screening machines use screens which have a screen fabric stretched in a frame and substantially planar, which is oriented substantially perpendicular to the desired direction of flow of the material. Screenings which do not fulfill the classification conditions imposed by the openings in the screen fabric remain behind in the screen; only screenings that fulfill the classification condition can leave the screen.

While these classes of screening machines are well suited for use in applications where the screenings are fed in portions due to the screen arrangement they use, they are poorly suited for use with continuous feed of screenings. Particularly in such cases, centrifugal screening machines, also known as eddy-current screening machines, are used. Such a screening machine is known for example from DE 30 19 113 C2. In the type of screening machine referred to in this patent application as a "centrifugal screening machine", the screening system used comprises a tubular screen inside which the screenings are conveyed The tubular screen can consist of a tube with screen openings arranged directly in the wall of the tube but it may also be stretched by a screen mesh strapped to a screen frame defining at least the length and cross section of a tube so that the screen mesh forms at least part of the surface of the tubular screen, and more particularly not only in one plane In addition, embodiments are also conceivable in which both a tube with screen openings and an additional screen fabric surrounding this tube are provided.

For the purposes of this patent specification, a tube is an elongate hollow body with an opening passing through it lengthwise and generally of cylindrical cross-section; accordingly, the adjective "tubular" describes an article having the shape of a tube as defined above.

The sieving effect of the tubular sieve is achieved by causing a passage of the material to be sieved through the sieve openings and / or the sieve fabric which forms at least part of the tube wall. To ensure that there is a significant material throughput through the screen openings and / or the screen fabric, there are two particularly widespread approaches: One possibility, which is used in particular at relatively low concentrations of the material to be screened, is inside the tubular screen to provide the material transporting fluid flow which is provided with such a swirling, that a material transport through the screen openings and / or the screen fabric comes.

An alternative, especially at high concentrations of the material to be screened possibility used is that inside the tubular sieve a so-called "racket system", ie a usually made of metal rotor linkage is provided, which is guided along the wall of the tubular screen and pushes the screenings through the screen openings and / or the screen fabric and optionally provided radial openings of the frame structure.

Generally, the problem arises in screen systems, even temporary blockage of the screen openings and / or screen fabric, as e.g. By agglomeration of Siebgutteilchen can be done to prevent and ensure the highest possible throughput of screenings through the mesh. In sieve systems, which find use in centrifugal screening machines, this problem is exacerbated mostly because the screenings - for example, by a racket system - in the Sieböfnungen and / or the screen fabric is coated.

For sieve systems with flat sieves, in which the sieve fabric forms a plane spanned in a sieve frame, it is known to reduce the tendency to block the sieve fabric by means of ultrasound excitation. Such a screening system can be found for example in DE 4418175. However, a simple transfer of this approach to sieve systems with tubular sieves fails. The desired significant increase in throughput is not achieved. Starting from this prior art, the problem arises to provide a sieve system for a Zentrifugalsiebmaschine with a tubular sieve and a method for operating a tubular sieve, which leads to an increase in the achievable throughput of Siebgut.

The invention is based on the finding that excitation of a tubular screen by means of ultrasound leads to a significant increase in the throughput of screenings, when the amplitude of the ultrasonic excitation has both a component in the radial direction and a component in the axial direction of the tubular screen.

A sieve system according to the invention therefore has a tube which has at least one section (12) with sieve openings which are arranged directly in the wall of the tube and / or a sieve cloth which is placed on a sieve frame which at least has the length and the cross section of a sieve frame Defined tube is stretched, so that the mesh forms at least a portion of the wall of the tubular sieve, and at least one ultrasonic converter and at least one arranged between ultrasonic converter and the screen frame feed line conductor, wherein the tube or the screen frame by means of the ultrasonic converter and the lead scarf conductor an ultrasound excitation can be exposed and wherein the one or more lead conductors are configured such that the amplitude of the ultrasound excitation transmitted to the tube or screen frame comprises a component in a direction perpendicular to a central axis of the tubular screen and a component in a parallel direction having the central axis of the tubular screen. By providing such longitudinal and transverse components of the oscillation amplitude, on the one hand, the propagation of the ultrasound over the entire tubular sieve is ensured and on the other hand at each location a component of the vibration amplitude is provided, which ^' causes an intensive, throughput-promoting interaction between screenings and screen openings and / or screen mesh.

In a preferred embodiment, when ultrasonic excitation, both components of the amplitude of the ultrasonic excitation at a single point of contact between the feed line conductor and pipe or screen frame are transmitted. This allows a particularly cost-effective design with only one ultrasonic converter and only one feed line sound conductor.

This can be achieved, in particular, if the one feed line sound conductor has at least one curved area. Advantageously, the angle of curvature of the curved region is above 0 degrees and at most at 90 degrees, with a bend angle of 90 degrees being most suitable for most applications.

The use of a feed line conductor with a diameter of 12 mm has proven to be particularly advantageous.

A particularly robust and interference-resistant embodiment of the screen system is obtained by providing firm connections between the feed line conductor and the surface of the tube or surface of the screen frame. This can be done in particular by screwing or welding.

Furthermore, the provision of a fixed connection between the feed line conductor and the ultrasonic converter has proven to be conducive to the robustness and interference resistance of the screening system. Here, in particular, the screwing is suitable to produce such a solid connection.

If one wishes to obtain a sieve system in which a particularly high vibrational energy can be introduced into the sieve fabric, this can be achieved by providing more than one ultrasound converter and more than one feeder sound conductor.

Moreover, if more than one lead acoustic conductor is present and the tube or screen frame is ultrasonically excitable via the lead acoustic conductors, then the presence of a component in a direction perpendicular to a central axis of the tubular screen and a component in a direction parallel to the central axis may also be present of the tubular screen can be achieved in that the direction of the amplitude of the ultrasound excitation, which is transmitted through different feed line conductors to the pipe or the screen frame, is different. This embodiment of the invention has proven particularly useful when a particularly targeted

Adjusting the size of the two components of the amplitude of the ultrasonic excitation is necessary.

For the operation of such a screen system, it is also useful to arrange the existing ultrasonic converter outside the Siebgutstromes, since these can cause material changes in the screenings on the one hand and on the other dirty and can be damaged in Siebgutstrom. This goal can be realized if the screen system has a housing which prevents leakage of screenings into the environment and all existing ultrasonic converters are arranged outside the housing. The tubular screen systems described herein are particularly suitable for use in centrifugal screening machines.

In the method according to the invention for operating a sieve system with a tubular sieve, a pipe with sieve openings, which are arranged directly in the wall of the tube and / or a screen fabric, which strained on a screen frame, which defines at least the length and the cross section of a tube is so that the screen fabric at least forms part of the surface of the tubular screen, the tube with the screen openings or the screen frame with an ultrasonic excitation with an amplitude are excited, which is a component in the direction perpendicular to a central axis of the tubular sieve and a component in a direction parallel to the central axis of the tubular screen. The presence of these two amplitude components ensures that, on the one hand, a propagation of the vibrations caused by the ultrasonic excitation takes place over the entire tubular sieve, while at the same time good conditions for increasing the efficiency of the sieving process are ensured at each point of the sieve.

The process can be carried out with particularly low material expenditure if the amplitude which a component has in the direction perpendicular to a central axis of the tubular sieve and a component in a direction parallel to the central axis of the tubular sieve is produced by exactly one feed line sound conductor.

A particularly well controllable size distribution of the two components of the oscillation amplitude is achieved if the amplitude, which is a component in the direction perpendicular to a A central axis of the tubular sieve and a component parallel to the central axis of the tubular sieve, is produced by more than one feeder acoustic conductor.

It has been shown that a further significant increase in the throughput can be achieved by not working at a fixed excitation frequency, but the frequency of the ultrasonic excitation is varied. This is done by appropriate control of the ultrasonic converter with a control unit. The range in which the frequency is varied is advantageously between 32 kHz and 38 kHz. Particularly good results can be achieved if the frequency modulation is carried out by sweeping, that is, by a continuous frequency variation.

Specific embodiments of the invention will be discussed in detail with reference to the following figures. It shows:

1 shows a sieve system with a tubular sieve according to a first embodiment of the invention

2 purely screening system with a tubular sieve according to a second embodiment of the invention

3 shows a sieve system with a tubular sieve according to a third embodiment of the invention

Identical components are, unless otherwise indicated, provided with identical reference numerals in all figures.

FIG. 1 shows a screening system 1 with a tubular sieve 10, which in the illustrated embodiment has the form of a hollow sieve 10. Cylinder has. The tubular sieve 10 consists of a tube 11 having two annular end portions 111, 112, between which a cylindrical portion 113 is disposed. In the cylindrical region 113 are a plurality of brightly illustrated areas 114, in which the tube 11 has numerous small screen openings, which are not individually drawn because of their small size for reasons of clarity. In addition, the tube 11 in the cylindrical portion 113 has a plurality of reinforcing ribs 12, which are drawn dark to distinguish them from the areas with screen openings.

Furthermore, the screen system 1, two ultrasonic converters 13 and two feed line conductor 14. The use of two feed scarf ladders 14 and two ultrasonic converters 13 in this embodiment serves, in particular, to increase the vibrational energy transmitted to the tube 11. It has the central axis A-A.

The tube 11 is connected via the feed line conductor 14 with the

Ultrasonic converters 13 mechanically connected. The lead scarf ladder 14 are curved. As indicated by the arrows in Figure 1, an ultrasound transducer with an oscillation amplitude, which is directed parallel to the central axis AA, fed into the feed line conductor 14 by the ultrasonic converter 13. The curvature of the feed line conductor 14 causes the oscillation amplitude receives an additional, perpendicular to the central axis AA component. The exact division of the components is determined by the geometric configuration of the feed line conductors 14, in particular by their curvature. At contact points 115, the ultrasonic vibration is transmitted to the tube 11. The vibration caused thereby spreads via the pipe 11. In this case, the longitudinal component of the amplitude of the ultrasound excitation particularly promotes a propagation of the ultrasound over the entire length of the tubular sieve, while the transversal component particularly increases the efficiency of the sieving process at any given location of the tube 11.

FIG. 2 shows a screening system 2 with a tubular sieve 10, which in the illustrated embodiment has the shape of a hollow cylinder. The tubular sieve 10 consists of a tube 11 which has two annular end portions 111, 112, between which a cylindrical region 113 is arranged. In the cylindrical region 113 are a plurality of bright areas 114, in which the tube

11 has numerous small screen openings, which are not drawn individually because of their small size for reasons of clarity. In addition, the tube 11 in the cylindrical region 113 has a plurality of reinforcing ribs

12, which are drawn dark to distinguish them from the areas with sieve openings.

Furthermore, four ultrasonic converters 13 and four supply sound conductors 24 belonging to the screening system 2 can be seen. The

Use of four feed scarf ladders 24 and four ultrasonic converters 13 in this embodiment serves, in particular, to increase the vibration energy transmitted to the tube 11. The sieve system has the central axis AA. The tubular sieve is surrounded by a housing 15, through which the feed line conductors 14 are guided. The ultrasonic converter 13 are outside the housing and thus outside the area in which a contact with screenings would be possible arranged.

The tube 11 is mechanically connected via the feed line conductors 14 with the ultrasonic converters 13. The feed line conductors 24 are designed in FIG. 2 with two regions of curvature. As already explained with reference to FIG. 1, an ultrasound vibration with an oscillation amplitude, which is directed parallel to the central axis A - A, is fed into the supply line sound conductor 24 by the ultrasound converters 13. The curvature of the feed line conductor 24 causes vibration amplitude receives an additional, perpendicular to the central axis A-A component. The exact division of the components is determined by the geometric configuration of the feed line conductors 24, in particular by their curvature. In the embodiment of Figure 2 is therefore in particular a different division of the components of the amplitude of the ultrasonic excitation than in the embodiment of Figure 1, since the geometric configuration of the feed line conductor 24 is different from that of the feed line conductor 14 in Figure 1. In addition to the bending angles play Also radii of curvature and cross-section of the feed line conductors 14 and 24 a crucial role for the achieved size distribution of the two components of the amplitude of the ultrasonic excitation.

At contact points 115, the ultrasonic vibration is transmitted to the tube 11. The vibration of the tube 11 caused thereby spreads across the tube 11. In this case, the longitudinal component of the amplitude of the ultrasound excitation in particular promotes a propagation of the ultrasound over the entire length of the tubular sieve, while The transverse component particularly increases the efficiency of the screening process.

FIG. 3 shows a screening system 3 with a tubular sieve 30. The sieve 30 consists of a sieve cloth 32 and a sieve frame 31. The sieve frame consists of four annular sections 311, 312, 313, 314 which define the cross section of a tube or hollow cylinder , which are connected to each other via two connecting strips 316, 317, which likewise belong to the frame, by means of which the length of the tube is predetermined. By the components of the screen frame length and cross section of the tube are given in this way. The screen cloth 32 is stretched on the screen frame such that the screen cloth 32 forms at least part of the surface of the tubular screen 30. In particular, the screen cloth 32 is not arranged in one plane only. It would also be possible to use fewer or more annular sections 311, 312, 313, 314 and / or fewer or more connecting strips 316, 317 as long as at least two annular sections 311, 312, 313, 314 and at least one connecting strip 316, 317 available.

Furthermore, FIG. 3 shows two ultrasound converters 13 and two feed sound conductors 34, which each have two regions of curvature in FIG. The feed line conductors are connected to the screen frame 31 at contact points 315. During operation of the screening system 3, an ultrasound vibration with an oscillation amplitude, which is directed parallel to the central axis AA of the tubular screen 30, is fed into the supply sound conductors 34 by the ultrasonic converters 13. The curvature of the feed line conductors 34 results in the oscillation amplitude being given an additional component perpendicular to the central axis AA. At contact points 315, the ultrasonic vibration is transmitted to the screen frame 31. The result Vibration of the screen frame 31 caused at the contact points 315 propagates over the entire screen frame 31 and at the same time leads to ultrasound excitation of the screen fabric 32. In this case, the longitudinal component of the amplitude of the ultrasound excitation particularly propagates the ultrasound over the entire length of the tubular screen 30 promoted, while the transverse component, the efficiency of the screening process and the throughput through the screen fabrics 32 particularly increases.

LIST OF REFERENCE NUMBERS

I sieve system (first embodiment) 2 sieve system (second embodiment)

3 sieve system (third embodiment)

10 tubular sieve

II pipe

12 pipe section with screen openings 13 ultrasonic converter

14 cable conductor

15 housing

24 supply conductor

30 tubular sieve 31 sieve frame

32 screen mesh

34 Conductance conductor

III End section 112 End section 113 Cylindrical section

114 reinforcing ring

115 contact point

311 annular portion of the screen frame

312 annular portion of the screen frame 313 annular portion of the screen frame

314 annular portion of the screen frame

315 contact point

316 connection bar

317 connection bar

Claims

claims

A sieving system (1, 2, 3) having a tubular sieve (10, 30), which has a tube (11) which has at least one section (12) with sieve openings, which are arranged directly in the wall of the tube (11) , and / or the one screen frame (31) defining at least the length and the cross-section of a tube, and a screen cloth (32) stretched on the screen frame (31), so that the screen cloth (32) at least a part the wall of the tubular sieve (10,30) forms, characterized in that the sieve system (1,2,3) at least one ultrasonic converter (13) and at least one between the Ultraschallkonver- ter (13) and the tube (11) or The sieve frame (31) arranged inlet conductor (14,24,34), wherein the tube (11) or the sieve frame (31) by means of the ultrasonic converter (13) and the feed line conductor (14,24,34) of an ultrasonic excitation is exposed and the supply line sound conductor (14,24,34) so out stating that the amplitude of the ultrasonic excitation transmitted to the tube (11) or to the screen frame (31) has a component in the direction perpendicular to a central axis (AA) of the tubular screen (10, 30) and a component parallel to the central axis (AA) of the tubular sieve (10,30).

2. sieve system (1,2,3) according to claim 1, characterized in that in ultrasonic excitation, the amplitude of the ultrasonic excitation at a contact point (115,315) to the tube (11) or the sieve frame (31) has a component in the direction perpendicular to the central axis (AA ) of the tubular sieve (10,30) and a component in a direction parallel to the central axis (AA) of the tubular screen (10, 30).

3. Screening system (1,2,3) according to claim 2, characterized in that at least one supply line sound conductor (14, 24, 34) has at least one curved region.

4. Screening system (1,2,3) according to claim 3, characterized in that the curved region has a curvature angle which is greater than 0 degrees and which is a maximum of 90 degrees.

5. Sieving system (1, 2, 3) according to claim 4, characterized in that the

Curvature angle is 90 degrees.

6. Screening system (1, 2, 3) according to any preceding claim, wherein the at least one supply line sound conductor (14, 24, 34) has a diameter of 12 mm.

7. Screening system (1, 2, 3) according to any one of the preceding claims, wherein at least one supply line sound conductor (14, 24, 34) is screwed or welded to the surface of the pipe (11) or the screen frame (31).

8. sieve system (1,2,3) according to any preceding claim, characterized in that at least one ultrasonic converter (13) with at least one feed line sound conductor (14,24,34) are screwed.

9. Screening system (1, 2, 3) according to any preceding claim, wherein more than one ultrasonic converter (13) and more than one supply line sound conductor (14, 24, 34) are present.

10. sieve system (1,2) according to claim 1, characterized in that more than one inlet conductor (14,24,34) is present and the tube (11) or the sieve frame (31) via the supply line conductors (14,24, 34) can be excited by ultrasound, wherein the direction of the amplitude of the ultrasound excitation by different supply line sound conductors (14,24,34) is different.

11. sieve system (1,2,3) according to any preceding claim, characterized in that the sieve system (1,2,3) comprises a housing (15) which prevents leakage of screenings in the environment and that all existing ultrasonic converter (13 ) are arranged outside of the housing (15).

12. Zentrifugalsiebmaschine with a screening system (1,2,3) according to any preceding claim.

A method of operating a screening system (1,2,3) having a tubular screen (10,30) comprising a tube (11) having at least a portion (12) with screen openings disposed directly in the wall of the tube , owns and / or which has a screen frame (31) and a screen fabric (32), in which the tube (11) or the screen frame (31) is excited by means of ultrasound to vibrate,. characterized in that the tube (11) or the screen frame (31) is provided with an ultrasound excitation is excited whose amplitude has a component in the direction perpendicular to a central axis (AA) of the tubular sieve (10,30) and a component in the direction parallel to the central axis (AA) of the tubular sieve (10,30).

A method according to claim 13, characterized in that the amplitude of a component perpendicular to a central axis (AA) of the tubular screen (10, 30) and a component parallel to the central axis (AA) of the tubular screen (10 , 30) is generated by exactly one feed line sound conductor (14,24,34).

A method according to claim 13, characterized in that the amplitude of a component perpendicular to a central axis (AA) of the tubular screen (10, 30) and a component parallel to the central axis (AA) of the tubular screen (10 , 30) is generated by more than one lead acoustic conductor (14, 24, 34).

16. A method according to any preceding claim, wherein a frequency of ultrasonic excitation is varied.

17. The method according to claim 16, characterized in that the frequency of the ultrasonic excitation is varied continuously in a range between 32 kHz and 38 kHz.

18.Use of a method according to any one of claims claim 13 to 17 for operating a Zentrifugalsiebmaschine.