EP0545144A2 - Screening drum - Google Patents

Abstract

In a screening drum, in particular for domestic waste or industrial waste similar to domestic waste, compost, scrap of any kind from shredders etc., having interior fittings there is an improved operation if web-like fingers (8, 14) pointing towards the centre axis (5) of the drum (1) are fastened to the interior surface of the perforated screen (6). <IMAGE>

Description

The invention relates to a sieve drum, in particular for household waste or household waste-like commercial waste, compost, shredder scrap of any kind, with fingers attached to the inner surface of the perforated screen.

In order to sieve a screened material practically one hundred percent, it would basically take an infinitely long sieve section. In practice, however, only finite lengths of the sieve drum are allowed, which correspond approximately to three to four times the sieve drum diameter, although the pure sieve section is somewhat shorter; In the case of known drum screens for larger throughputs, drum screens of 8 to 12 m in length are required, for example. For setup and cost reasons, and above all because of the very high weight of the material to be screened, which weighs on the impellers of the sieve drum, the sieve drums for steel shredder scrap, for example, are even shorter and are only half of the values given above. So that a good screening result can be achieved, it is therefore necessary to ensure that the screenings are mixed very well by means of additional internals. As a rule, guide and mixing blades are therefore arranged in the interior of the drum in the form of flat sheet metal strips and of different lengths, heights and, if necessary, in an inclined position.

A screening drum of the type mentioned at the outset has become known from US Pat. No. 4,018,675. The internals in the form of radially inward fingers directed against the drum axis are arranged in rows running parallel to one another. The cylindrical fingers, supported by the variation in the rotational speed of the sieve drum, should ensure that, in particular, sieve material sized larger than the sieve perforation is accelerated in the sieve drum and passed to the overflow at the other end of the sieve drum.

A screening drum with internals in the form of rectangular, web-like fingers is also known from FR 26 37 514 A1, but there for classifying granular screenings, namely cereal grains, e.g. Oats. Several fingers arranged side by side in the inside of the sieve drum form combs which are arranged parallel to the axis of the sieve drum and directed radially inwards.

So that not only a classification but also a sorting of the material to be screened can be achieved, it is known from EP-OS 0 008 621 to also provide such internals in the interior of the screen drum, which is mounted at a slightly inclined angle, in addition to storage devices in the form of an impeller crushing garbage into bales or filling them in paper or plastic bags; for this purpose, crushing internals with sawtooth-shaped driver plates and baffle plates are installed, which, together with circumferential cleaning brushes arranged parallel to the axis, enable classification and sorting. The stowage devices result in a compact, short design of the screening drum, and the selective crushing, in particular brittle screenings, in the waste mixture such as glass, porcelain, bricks from building rubble etc., serve the baffles that fall within the falling stream of material the drum are effective, so that the screenings can be sorted after crushing.

A sieve drum with radially arranged on the inside of the drum, triangular impact plates for pre-comminution of the waste and with at least one storage device inside the drum has also become known from EP-PS 0 070 292. The sieve drum is octagonal in cross section there, and the stowage devices each consist of four rectangular sheets, one side of which is equal to the width of the octagon side and the other side of which is the catheter length of the right-angled, isosceles triangle above the octagon side. The rectangular sheets are arranged in one plane in such a way that a square passage opening remains free in the middle of the sieve drum. The impact plates are offset helically in the accumulation sections between two accumulation devices, the lower part of the direction of rotation running ahead.

Various disadvantages have been found in the known screening drums. Since, due to the known arrangement and design, there are many screen openings in the rotating shadow of the internals, these screen openings can no longer participate in the screening, which is equivalent to a reduction in the free screen area. The mixed screenings are taken along in the direction of rotation of the screening drum, but with a normally filled drum it does not hit the screen openings when falling down, but falls on the other screenings or on the internals. Critical screenings that tend to cake (including moist materials, composts) often cause unwanted caking in the rotating shade of the internals, which completely closes a large part of the screen openings after a certain operating time. Screenings that tend to cling to each other, such as steel shredder scrap, form clusters of screenings (sausage formation) which rotate in the longitudinal direction of the drum; this effect is particularly favored rather than reduced by shovel-like installations.

The invention has for its object to provide a design and arrangement of the internals in a screening drum, with which the above disadvantages can be avoided and an improved mode of operation results.

This object is achieved in that three fingers form a built-in star. In an alternative embodiment, individual fingers in the screen surface development can lie on straight lines running at an angle to the conveying direction. With these fingers that are relatively long compared to their thickness (or diameter), e.g. consist of flat iron with the dimensions 150 mm x 15 mm and are 600 mm long, and especially for light, moist screenings, e.g. Compost, relatively thin and should be arranged in a more frequent distribution, can surprisingly achieve different effects at the same time. This is because the screenings are loosened and mixed constantly, maintaining constant contact with the screen openings and largely preventing the screenings from caking; in addition, the sieve openings not involved in the sieving process and lying in the rotating shadow are reduced to a minimum and the sausage formation of the sieved material is prevented by a cutting effect of the fingers acting in the direction of rotation.

With the three fingers assembled to form a built-in starter, preferably one finger of each built-in star with its narrow side pointing in the direction of rotation, suitable, especially for heavy screenings (for example shredder scrap) achieve effective and stable internals, the sausage-avoiding cutting effect can be further increased if, according to a preferred embodiment of the invention, the finger pointing with its narrow side in the direction of rotation is shorter than the other two fingers of the associated built-in star. The shorter, wedge-shaped, leading finger also means an even better mixing of the material and increased clearance of the sieve openings.

In the case of built-in stars which have a length corresponding to at least 0.2 times the drum diameter, an optimized mode of operation of the sieve drum which ensures constant loosening and mixing can be achieved.

Finally, the quality of the screen is also promoted by the fact that the fingers or built-in stars in the screen surface development lie on straight lines that run at an angle to the conveying direction, which in the case of a perforated screen composed of several parts result from the number of screen plates forming the perforated screen (depending on the drum size). The direction of inclination of the straight line is selected such that the fingers or mounting star initially lying on the feed side lag behind in the direction of rotation with respect to the adjacent ones lying on the same straight line. The built-in star is preferably arranged at the corners of the screen plates in order to increase the stability.

In the case of round bars as a single finger, one finger is also advantageously located at one corner of the screen plates, and further fingers are arranged at equal intervals on the straight lines inclined at an angle to the conveying direction in accordance with the previously described direction of rotation. The number of round iron fingers is therefore a multiple of the number of installation stars; with thin Round iron fingers have a maximum length of 0.1 x drum diameter.

Fig. 1

eine mit erfindungsgemäßen Einbauten in Form von Einbausternen versehene Siebtrommel, abgewickelt dargestellt;

Fig. 2

als Einzelheit vergrößert den in Fig. 1 strichpunktiert eingekreisten und mit "A" bezeichneten Trommelausschnitt;

Fig. 3

eine Seitenansicht des Gegenstandes der Fig. 2;

Fig. 4

als Einzelheit vergrößert den in Fig. 1 strichpunktiert eingekreisten und mit "B" bezeichneten Trommelabschnitt; und

Fig. 5

eine mit erfindungsgemäßen Einbauten in Form von Rundeisenfingern versehene Siebtrommel, abgewickelt dargestellt.

Further features and advantages of the invention result from the following description, in which exemplary embodiments of the subject matter of the invention are explained in more detail with reference to the drawing. Show it:

Fig. 1

a screen drum provided with internals according to the invention in the form of built-in stars, shown unwound;

Fig. 2

as a detail, the drum detail circled in FIG. 1 and labeled "A" is enlarged;

Fig. 3

a side view of the object of Fig. 2;

Fig. 4

enlarged as a detail the drum section circled in FIG. 1 and labeled "B"; and

Fig. 5

a screen drum provided with internals according to the invention in the form of round iron fingers, shown unwound.

A screen drum 1, which is driven by means not shown, of which only its unwound drum shell 2 is shown in FIGS. 1 and 5, has a screen 3 and a screen 4 is encapsulated by a fixed, cylindrical housing (not shown). The perforated screen 6 located between the screenings 3 and the screenings 4 is provided with numerous circular screen openings 7 (cf. the 2 and 4) and according to FIG. 1 consists of two (cylindrical) shots, each of which is composed of eight screen plates 10 arranged with their longitudinal axis in the conveying direction. Each shot preferably has a length of 1250 to 1500 mm, so that, depending on the desired length of the sieve drum, two to eight shots are generally joined together. The eight sieve plates mentioned per circumference and weft apply preferably to a drum diameter of 2.5 to 3.0 m.

1, several built-in stars 9 each consisting of three elongated, relatively long and thin fingers 8a, 8b and 8c in the area of the perforated screen 6 are welded to the webs located between the screen openings 7 in a uniformly distributed manner (see FIG. 2 to 4), namely there is a built-in star 9 in each corner of a screen plate 10. A finger 8a, which is shorter than the other two fingers 8b and 8c of the built-in star 9, is with its free, narrow end face in the direction of rotation 11 or 12 (the direction of rotation arrow 12 is shown in dashed lines in FIG. 1) pointing perpendicular to the central axis 5. Instead of individual flat irons, an angle iron can also be used for the fingers 8b and 8c of each built-in star 9. In the context of the invention, the built-in star can also be produced as cast steel parts.

In the distribution according to FIG. 1, twelve built-in stars 9 are provided, specifically in an arrangement in which three built-in stars 9 each lie on straight lines 13, 13a extending at an angle α to the conveying direction in the screen surface processing, and each of the fingers 8a in the direction of rotation 11 or 12 points. If the screening drum 1 rotates in the direction of the direction of rotation arrow 11 shown with solid lines, the installation star 9 is as in FIG. 1 with solid lines and in FIG. 2 as a detail shown in the form of an upside-down Y arranged on the straight line 13. If, on the other hand, the drum rotates in the direction of the directional arrow 12 shown in dashed lines in FIG. 1, the installation stars are shown in dashed lines in FIG. 1 and, as a detail in FIG. 4, are arranged in a Y direction on the straight line 13a. For reasons of stability, the built-in star 9 is placed in the screen plate corners. The number of sieve plates 10 (lengthways and over the circumference) differs according to the different drum dimensions. The number of built-in stars 9 thus changes, but the arrangement described remains unchanged.

Due to the described design and arrangement of the fingers 8 or built-in star 9, the material to be screened is constantly loosened and mixed on its way from the entry 3 to the discharge 4 without losing contact with the screen openings 7. The screen openings 7, which are not involved in the screening process due to the installation star 9, are reduced to a minimum, and in the direction of rotation there is a cutting effect which prevents the sausage from forming the screenings (see FIG. 3).

It is also within the scope of the invention, especially in the case of light, moist screenings (for example compost), if, according to FIG. 5, 9 single fingers 14 made of round bars, preferably 20 mm in diameter, are provided instead of the built-in star 9, which need not be put together to form stars . Deviating from the built-in stars 9, the maximum finger length here is 0.1 x drum diameter, and the number of fingers is significantly larger (see FIG. 5). The arrangement of the fingers 14 in corners of the screen plates 10 is analogous to that of the built-in star 9; further fingers 14 are arranged in the area of the angular line α, ie straight lines 13 and 13a at approximately equal intervals (see FIG. 5). The sieve drum turns in the direction of the arrow 11, the round iron fingers 14, as shown in FIG. 5, are arranged on the straight line 13; If the sieve drum rotates in the direction of the dashed arrow 12, the round iron fingers 14 are arranged on the straight line 13a.

The installation star 9 are preferably used for shredder scrap and all materials that contain heavy parts and inhomogeneous large parts, e.g. Garbage and untreated incinerator slag. The round iron fingers 14 are used for light and moist fine material, such as for composts and crushed residual slag made from pre-screen overflow material.

As already mentioned, the type of internals according to the invention is selected essentially as a function of the feed material, but also taking into account the sieve hole diameter required for the desired sieve passage. For example, built-in stars are particularly suitable for sieve hole diameters ≧ 40 mm, while round iron fingers are intended for sieve hole diameters ≦ 60 mm, with the choice in the diameter transition range depending on other criteria such as moisture, homogeneity, crosslinking, density and the like. depends on the feed material.

Claims (14)

Sieve drum, in particular for household waste or household waste-like commercial waste, compost and shredder scrap of any kind, with fingers attached to the inner surface of the perforated screen, characterized in that three fingers (8a, 8b, 8c) each form a built-in starter (9). Sieve drum, in particular for household waste or household waste-like commercial waste, compost and shredder scrap of any kind, with fingers attached to the inner surface of the perforated screen, characterized in that individual fingers (14) in the screen surface development on straight lines (13, 13a.) Running at an angle (α) to the conveying direction ) lie. Screen drum according to claim 1, characterized in that the fingers (8) consist of flat iron, the longitudinal axis of which points to the axis of rotation (5) of the screen drum (1). Screen drum according to claim 1 or 2, characterized in that a finger (8a) of each built-in star (9) points with its narrow side in the direction of rotation (11 or 12). Screen drum according to Claim 4, characterized in that the narrow side of the drum in the direction of rotation (11 or 12) pointing fingers (8a) is shorter than the other two fingers (8b, 8c) of the associated built-in star (9). Screen drum according to claim 5, characterized in that the shorter finger (8a) is bevelled on its upper, free end face in the direction of rotation. Screen drum according to one or more of claims 1 to 6, characterized in that the fingers (14) or built-in stars (8 or 9) have a length corresponding to at least 0.2 times the drum diameter. Screen drum according to claim 1 or 2, characterized in that the fingers are designed as round iron fingers (14). Screen drum according to one or more of claims 1 or 3 to 8, characterized in that the built-in stars (9) lie in the screen surface development on straight lines (13, 13a) running at an angle (α) to the conveying direction. Sieve drum according to Claim 2 or 9, characterized by an inclination direction of the straight line (13, 13a), in which the fingers (14) or built-in star (9) initially on the feed side (3) lie on the same in relation to those adjacent to the discharge (4) Lines (13, 13a) lie behind in the direction of rotation (11 or 12). Screen drum according to one or more of claims 1 to 10, characterized in that the perforated screen (6) is composed of several screen plates (10). Screening drum according to claim 9 or 10, characterized in that a built-in star (9) or finger (14) is arranged on at least one corner of the screen plates (10) forming the perforated screen (6). Screen drum according to one or more of claims 1 to 12, characterized in that the number of round iron fingers (14) is a multiple of the number of built-in stars (9). Screen drum according to claim 13, characterized in that one finger (14) is arranged in each corner of the screen plates (10) forming the perforated screen (6) and the remaining fingers (14) at equal intervals on the at an angle (α) to the conveying direction straight lines (13 or 13a).

Images