Sieving machine

Abstract

Screening machine 1 with a screen housing 2 in which several screen decks are arranged one above the other, wherein a front wall 7 has an inlet opening 23 for material to be screened and a rear wall 8 has an outlet opening 24 for screened material, wherein a feed unit 9 is arranged at the inlet opening 23 and a discharge unit 10 is arranged at the outlet opening 24, and wherein the screening machine 1 has an automatic explosion suppression system 34, which has at least one extinguishing agent container 11, 12, 13, 14 with at least one extinguishing agent line 15, 16, 17, 18, the least one of which has an outlet nozzle to direct an extinguishing agent from the extinguishing agent container 11, 12, 13, 14 towards the screen decks.The outlet nozzles of the at least one extinguishing agent line 15, 16, 17, 18 are oriented such that the extinguishing agent can be introduced into the sieve housing 1 through the inlet opening from the feed unit 9 or from a flange unit connecting the feed unit 9 to the front wall 7 and / or from the outlet unit 10 or from a flange unit connecting the outlet unit 10 to the rear wall 8 through the outlet opening.

Description

[0001] The invention relates to a screening machine according to the features in the preamble of patent claim 1.

[0002] WO 2022 259 280 A1 discloses a screening machine with a screening housing. The screening machine is equipped with an active extinguishing system. The extinguishing agent container is located on top of the screening machine. The extinguishing agent lines are rigid lances arranged on the side walls. Outlet nozzles of the lances are assigned to the various screening decks at different heights to suppress the spread of dust within the screening housing in the event of a dust explosion.

[0003] Based on this, the invention is based on the object of improving such a screening machine in such a way that the propagation of an explosion is more effectively suppressed not only within the screening housing, but in particular in the area of ​​the inlet opening or in the area of ​​the outlet opening of the screening machine.

[0004] This object is achieved in a screening machine having the features of patent claim 1.

[0005] The subclaims relate to advantageous developments of the invention.

[0006] The screening machine according to the invention comprises a screening housing in which several screening decks are arranged one above the other. The screening housing has an upper wall, a lower wall, opposite side walls, a front wall, and a rear wall. An inlet opening for material to be screened is arranged on the front wall, and an outlet opening for screened material is arranged on the rear wall. A feed unit is located at the inlet opening, and an output unit is located at the outlet opening. The screening machine has an explosion suppression system that is activated by a sensor as soon as an explosion parameter is detected by the sensor. The explosion suppression system comprises at least one extinguishing agent container with at least one extinguishing agent line, which in turn has at least one outlet nozzle for directing an extinguishing agent from the extinguishing agent container toward the screening decks. The extinguishing agent is, in particular, an extinguishing powder, i.e., a dry extinguishing agent.

[0007] The outlet nozzles of the at least one extinguishing agent line are oriented such that the extinguishing agent can be introduced into the screen housing through the inlet opening from the feed unit or from a flange unit connecting the feed unit to the front wall, and / or can be introduced into the screen housing through the outlet opening from the outlet unit or from a flange unit connecting the outlet unit to the rear wall. The flow path of the extinguishing agent, beginning at the outlet nozzle and moving toward the endangered area, i.e., toward the interior of the screen housing, therefore also passes through the inlet opening and / or the outlet opening of the screen housing.

[0008] The screening machine according to the invention with the aforementioned explosion suppression system is designed to provide explosion protection for the screening machine, and in particular the area of ​​the screen plates, i.e., to detect an incipient explosion using flame and / or pressure sensors and to suppress explosions during the start-up phase by quickly introducing extinguishing agents. Ideally, explosion isolation from adjacent system components A is also provided. The term explosion isolation refers to a principle of structural explosion protection in which the effects of an explosion in the form of explosion pressure or flames are prevented from spreading and penetration into other system components is prevented.The system according to the invention primarily concerns systems for the active suppression of explosions. Depending on the system design, there is the option of decoupling by constructing an extinguishing agent barrier. According to the invention, the extinguishing agent is introduced directly into the screen housing through the inlet or outlet opening. Active systems include detection and control devices. According to the invention, at least one detector, which responds to pressure or flames, detects the explosion and triggers protective measures, in this case the discharge of extinguishing agent from the at least one extinguishing agent container.

[0009] The dust generated during the screening of organic products, such as wood or fiber materials, is explosive. Incipient explosions should be detected and suppressed at their source, and explosion propagation that enters the screen from connected system components should be decoupled within the screen.

[0010] The outlet nozzles are oriented so that the extinguishing agent flows from outside into the inlet or outlet opening and into the sieve housing.

[0011] The active explosion suppression system designed according to the invention can be installed as a supplement to or as a replacement for active explosion suppression systems that act exclusively on the interior of screen housings and that do not have a center of action in the area of ​​the inlet opening or outlet opening, ie as a supplement to or as a replacement for active explosion suppression systems that are arranged on the side walls of the screen housing.

[0012] In an advantageous development of the invention, the at least one extinguishing agent line is arranged on the feed unit, also referred to as a hopper, and / or on the outlet unit. If alternative flange units are provided as intermediate components for connecting the feed unit and / or the outlet unit to the respective ends of the screen housing, the at least one extinguishing agent line can also be located on the flange units.

[0013] The effective range of the introduced extinguishing agent and also the redundancy are increased if an extinguishing agent line is arranged on either side of the feed unit and / or the outlet unit. According to the invention, the feed unit or the outlet unit is somewhat narrower than the screen housing, so that the said at least one extinguishing agent line is arranged in the transition area between the wider screen housing and the narrower feed unit or outlet unit. The extinguishing agent line is therefore not attached to the screen housing, but to attachments that serve to supply material to the screen housing or to drain material from the screen housing. These attachments can also be retrofitted / converted to existing screening systems.For example, flange units suitable for the respective sieve housing can be offered, which are designed to introduce extinguishing agents with appropriately oriented outlet nozzles through the inlet opening or outlet opening into the sieve housing.

[0014] The outlet nozzles used are preferably oriented so that the respective jet cone is directed completely into the inlet and / or outlet openings, in order to achieve the most complete coverage of the inlet and / or outlet openings and the screen housing. This is preferably achieved when multiple extinguishing agent lines are present, where the jet cones overlap or intersect. The overlap can occur horizontally and / or vertically.

[0015] Depending on the desired orientation of the outlet nozzles, the feed unit can have a funnel-shaped transition area adjacent to the front wall and / or the outlet unit can have a funnel-shaped transition area to which the at least one extinguishing agent line is attached. The funnel-shaped transition area can also be provided on corresponding flange units arranged adjacent to the rear wall or the front wall. The front arrangement is a funnel-shaped extension. In the rear arrangement, the funnel tapers in the direction of material flow of the screened material. The funnel shape has the advantage of improving material flow in the transition area from the feed unit to the individual screen decks. At the same time, the inclination of the funnel-shaped transition area is used to position the extinguishing agent lines with the outlet nozzles arranged on them according to the desired direction of action.For this purpose, the funnel-shaped transition area is preferably at an acute angle to the front wall and / or the rear wall, with the outlet nozzles having a jet cone with a jet cone center axis that is preferably perpendicular to the funnel-shaped transition area. It is assumed here that the funnel-shaped transition area is a flat surface. The outlet nozzles are intended to introduce the extinguishing agent directly through the inlet opening or outlet opening into the screen housing without the need for baffle or deflection plates. The solution according to the invention thus also avoids the replacement of deflection plates for the extinguishing agent, which may be necessary after an explosion. In the event of an explosion, the extinguishing agent lines and outlet nozzles according to the invention are, in particular, reusable.

[0016] The invention does not exclude the use of baffles.

[0017] The extinguishing agent lines are preferably rigid ducts, such as tubular hollow sections with a round or square cross-section. The outlet nozzles are typically sealed with bursting discs to prevent the entry of sieved material during operation. The bursting discs are replaceable. In standby mode, the extinguishing agent lines are only subjected to atmospheric ambient pressure, so the bursting discs are not subjected to stress.

[0018] Screening machines are preferably configured so that either the entire screen housing or the individual screen decks are vibrated by vibration generators to improve the screening results. Therefore, rigid pipes or hollow sections are preferred for the extinguishing agent lines, rather than hoses.

[0019] Due to their connection, albeit only indirect, to the screen housing via the above-mentioned attachments, the extinguishing agent lines influence the dynamic properties of the screening machine or the screen housing when subjected to vibration. It is considered advantageous if the explosion suppression system does not cause any imbalances and if the vibration behavior of the screen housing is not negatively influenced by uneven weight distribution. Therefore, in an advantageous development of the invention, the jet cone center axes of several outlet nozzles arranged in pairs on the feed unit and / or the outlet unit and / or on the flange units intersect in the region of a vertical center longitudinal plane of the screen housing. In other words, on the left and right sides of the inlet opening orAt least one outlet nozzle, preferably an arrangement of several outlet nozzles, can be arranged at each outlet opening, which are arranged mirror-symmetrically to the vertical central longitudinal plane of the screen housing. In this case, there is no left / right imbalance in the area of ​​the screening machine. Additional weight is exerted on the screen housing by the extinguishing agent containers of the explosion suppression system if these extinguishing agent containers are attached to the upper wall of the screen housing. If several extinguishing agent containers are arranged on the upper wall of the screen housing, they should preferably be arranged point-symmetrically to the central vertical plane of the screen box, so that no asymmetry is created by the explosion suppression system according to the invention in the longitudinal direction of the screening machine, i.e. in the direction of material flow, from the inlet to the outlet.

[0020] Preferably, the entire explosion suppression system is designed with point symmetry, meaning that the transition areas in the corners of the extinguishing agent lines are configured and arranged in such a way that a point-symmetric weight distribution of the explosion suppression system results with respect to the screen housing. In this context, point symmetry essentially refers to the central vertical axis of the screen housing.

[0021] The screening machine according to the invention is characterized by improved explosion isolation of the inlet and outlet areas, as well as by improved explosion suppression of the screening housing. Due to its location on the feed unit or outlet unit, the explosion suppression system can be easily and effectively retrofitted to existing screening machines. The at least one sensor and the control unit belonging to the explosion suppression system can also be easily retrofitted or even considered during the design of the screening machine.

[0022] The explosion suppression system according to the invention can be combined with other fire protection devices, for example with other explosion suppression systems that act directly in the area of ​​the screen decks and are arranged, for example, in the area of ​​the long sides or in the middle of the screen housing in order to release the extinguishing agent multidirectionally and also in different height ranges.

[0023] The invention will be further explained below with reference to exemplary embodiments shown purely schematically in the drawings. They show: Fig. 1 a perspective view of a screening plant from above; Fig. 2 the screening plant of the Fig. 1 in the direction of view of a task unit; Fig. 3 a section along the line III-III in Fig. 2; Fig. 4 the detail IV from Fig. 3 in enlarged view; Fig. 5 a section along the line VV of the Fig. 2; Fig. 6 the detail VI from Fig. 5 in enlarged view; Fig. 7 the screening plant of the Fig. 1 in a plan view; Fig. 8 a perspective view of another embodiment of a screening plant.

[0024] The Fig. 1 shows a screening machine 1 with a cuboid screening housing 2, which has an upper wall 3, opposite side walls 4, 5, a lower wall 6 as well as an inlet-side front wall 7 and a rear wall 8. A feed unit 9, also referred to as a hopper, is arranged on the front wall 7. An output unit 10 is arranged on the rear wall 7. The screening machine 1 comprises an automatic explosion suppression system 34 with several extinguishing agent containers 11, 12, 13, 14. The extinguishing agent containers 11-14 are arranged on the upper wall 3 of the screening housing 2 and are each connected to extinguishing agent lines 15, 16, 17, 18, which extend in the vertical direction of the screening housing 2 next to the feed unit 8 and the outlet unit 10 in the transition area to the screening housing 2.The feed unit 9 and the outlet unit 10 are somewhat narrower than the sieve housing 2, so that, viewed in the longitudinal direction of the sieve housing 2, the extinguishing agent lines 15-18 do not protrude beyond the longitudinal sides 4, 5 of the sieve housing 2. Outlet nozzles are provided on the respective extinguishing agent lines 15-18 to introduce an extinguishing agent located in the extinguishing agent containers 11 to 14 into the sieve housing 2.

[0025] The Fig. Figure 2 shows a front view of the feed unit 9, showing that the two extinguishing agent lines 15, 16 are identically configured and arranged. They are located in a corner area of ​​the feed unit 9. Fig. 3 shows the positions of the cutting planes of the Fig. 3 and Fig. 5.

[0026] The Fig. Figure 3 shows the multiple screen decks 19 within the screen housing 2. The screen decks 19 are arranged one above the other and are loaded with a material to be screened. The feed unit 9 is located in the right-hand plane of the image. The material, classified into several fractions, is fed for further use via several outlets 20, separated by fraction.

[0027] In this embodiment, the screen housing 2 carries the respective extinguishing agent containers 11-14 on the upper wall 3, but the extinguishing agent lines 15-18 and the associated outlet nozzles 21, 22 are not located on a front wall 7 or on a rear wall 8 of the screen housing 2. Fig. 5 and Fig. 6 illustrate that the extinguishing agent is introduced via the extinguishing agent lines 15-18 not through openings in the front wall 7 or rear wall 8, but through an inlet opening 23 or an outlet opening 24, through which the screening material is also guided.

[0028] The sectional view in Fig. Figure 5 is a horizontal section through the screening machine 1. The extinguishing agent lines 15-18 are attached to funnel-shaped transition areas 25-28. The funnel-shaped transition areas 25-28 are part of the feed unit 9 or the outlet unit 10 and are not part of the screening housing 2. The sectional view of the Fig. 5 shows that an outlet 29 for the oversize grain is provided on the uppermost screen deck 19 within the outlet unit 10. The screen decks 19 ( Fig. 3) direct the material to the respective outlets 29 of the outlet unit 10. The material flow is positively influenced by the funnel-shaped transition areas 27, 28 on the outlet unit 10. The corner area is also used to arrange the outlet nozzles 21, 22 at different heights depending on the position of the individual screen decks 19.

[0029] The Fig. 6 shows a detail of the Fig. 5 in the corner area of ​​the feed unit 10. There is the funnel-shaped transition area 27 with the extinguishing agent line 17. The extinguishing agent line 17 has a rectangular cross-section. It is screwed to the flat transition area 27 via lateral flanges. It is located on an outer side of the transition area 27. In case of activation, the extinguishing agent would be projected into the image plane of the Fig. 6, and in practice coming from above, flow into the extinguishing agent line 17 and exit from the outlet nozzle 21 in the direction of the arrows in the area of ​​a jet cone 30. The two outer arrows illustrate the outer flanks of the jet cone 30. A jet cone center axis 31 is perpendicular to the funnel-shaped transition area 27. The configuration on the other long side of the feed unit 9 is identical, ie mirror-inverted to the vertical center longitudinal plane MLE of the screen housing 2. As a result, the jet cone center axes 31 intersect in the area of ​​the vertical center longitudinal plane MLE of the screen housing 2 ( Fig. 5). The outlet nozzles 21, 22 arranged on the feed unit 9 and the outlet unit 10 are oriented in particular such that they are diametrically opposite one another, so that the jet cone center axes 31 point directly towards one another and intersect in particular in the center of the screen housing 2. The angle W1, by which the funnel-shaped transition area 27 is inclined relative to the rear wall 8 ( Fig. 6), is accordingly adapted to the dimensions of the screen box 2, ie it depends primarily on the length and width of the screen box 2, but also on the extent to which the screen box 2 is wider than the feed unit 9 and the outlet unit 10. It is preferably an acute angle, which is usually less than 45° ( Fig. 6).

[0030] The Fig. Figure 6 also shows that the outlet nozzle 21 is arranged at a horizontal distance from the rear wall 8 and thus also from the rear outlet opening 24, so that the extinguishing agent can always be completely introduced through the open cross-section of the outlet opening 24 or through the open cross-section of the inlet opening 23. The exit point for the extinguishing agent is not located on the screen housing 2, but on the feed unit 9 or the outlet unit 10.

[0031] The Fig. Figure 7 shows, in a top view of the upper wall 3, a point-symmetrical arrangement of the extinguishing agent containers 11-14 and also of all other components of the explosion suppression system 34 with respect to a point of symmetry P, which lies in the region of the central vertical axis of the screen housing 2. The point-symmetrical arrangement with respect to the geometric center of gravity of the screen housing 2 is intended to prevent an imbalance of the screening machine 1 and thus a negative influence on the dynamic properties of the screening machine 1 in the event of vibration excitation.

[0032] The embodiment of the Fig. 7 differs from that of the Fig. 1 to 7. For components with essentially the same function, reference is made to the reference symbols and explanations of the Fig. 1 to 7 are used and referred to.

[0033] The difference from the first embodiment is that the extinguishing agent lines 15-18 are not arranged directly on the feed unit 9 or the outlet unit 10, but on separate flange units 32, 33, which are attached as separate components to the front wall 7 or the rear wall 8. These flange units 32, 33 are the link between the feed unit 9 and the front wall or between the outlet unit 10 and the rear wall 8. Just as in the previous embodiment, in this design the extinguishing agent is introduced into the sieve housing 2 via outlet nozzles at an inclined, funnel-shaped transition area of ​​the flange units 32, 33, either via an inlet opening in the front wall 7 or an outlet opening 24 in the rear wall 8.Reference is made to the preceding explanations, which also apply overall to the use of appropriately designed flange units 32, 33, with the only difference that the flange units 32, 33 are not an integral part of the feed unit 9 or the outlet unit 10, nor are they an integral part of the screen housing 2.

[0034] The flange units 32, 33 have the advantage that existing systems can be retrofitted with the explosion suppression system 34 according to the invention relatively easily, without significantly interfering with the supporting structure of the sieve housing 2. Reference symbol: 1 screening machine 2 sieve housings 3 upper wall 4 side wall 5 Side wall 6 lower wall 7 Front wall 8 Rear wall 9 Feed unit 10 Outlet unit 11 extinguishing agent containers 12 extinguishing agent containers 13 extinguishing agent containers 14 extinguishing agent containers 15 Extinguishing agent line 16 Extinguishing agent line 17 Extinguishing agent line 18 Extinguishing agent line 19 Screen deck 20 outlet on 10 21 Outlet nozzle 22 Outlet nozzle 23 Inlet opening in 7 24 outlet opening in 8 25 Transition area 26 Transition area 27 Transition area 28 Transition area 29 outlet in 19 30 jet cones 31 Beam cone center axis 32 flange unit 33 Flange unit 34 Explosion suppression system MLE Vertical mid-longitudinal plane of 2 P midpoint of 2 W1 angle between 8 and 27

Claims

[1] Screening machine (1) with a screen housing (2) in which several screen decks (19) are arranged one above the other, wherein the screen housing (2) has an upper wall (3), a lower wall (6), opposite side walls (4, 5), a front wall (7) and a rear wall (8), wherein the front wall (7) has an inlet opening (23) for material to be screened and the rear wall (8) has an outlet opening (24) for screened material, wherein a feed unit (9) is arranged at the inlet opening (23) and a discharge unit (10) is arranged at the outlet opening (24), and wherein the screen machine (1) has an automatic explosion suppression system (34), wherein the explosion suppression system (34) has at least one extinguishing agent container (11, 12, 13, 14) with at least one extinguishing agent line (15, 16, 17, 18), the least an outlet nozzle (21, 22) for directing an extinguishing agent from the extinguishing agent container (11, 12, 13, 14) towards the screen decks (19), characterized bythat the outlet nozzles (21, 22) of the at least one extinguishing agent line (15, 16, 17, 18) are oriented such that the extinguishing agent can be introduced into the sieve housing (1) through the inlet opening (23) coming from the feed unit (9) or from a flange unit (32) connecting the feed unit (9) to the front wall (7) and / or can be introduced into the sieve housing (1) through the outlet opening (24) coming from the outlet unit (10) or from a flange unit (33) connecting the outlet unit (10) to the rear wall (8). [2] Screening machine (1) according to claim 1, characterized by that the at least one extinguishing agent line (15, 16, 17, 18) is arranged on the feed unit (9) and / or on the outlet unit (10) and / or on the flange units (32, 33). [3] Screening machine (1) according to claim 1 or 2, characterized bythat an extinguishing agent line (15, 16, 17, 18) is arranged on both sides of the feed unit (9) and / or on both sides of the outlet unit (10). [4] Screening machine according to one of claims 1 to 3, characterized by that the outlet nozzles (21, 22) have a jet cone (30) which is directed completely into the inlet opening (23) and / or into the outlet opening (24). [5] Screening machine (1) according to one of claims 1 to 4, characterized by that the feed unit (9) adjacent to the front wall (7) and / or the outlet unit (10) adjacent to the rear wall (8) has a funnel-shaped transition region (25, 26, 27, 28) to which the at least one extinguishing agent line (15, 16, 17, 18) is attached. [6] Screening machine (1) according to one of claims 1 to 4, characterized bythat the flange unit (32, 33) adjacent to the front wall (7) and / or adjacent to the rear wall (8) has a funnel-shaped transition region to which the at least one extinguishing agent line (15, 16, 17, 18) is fastened. [7] Screening machine (1) according to claim 5 or 6, characterized by that the funnel-shaped transition region (25, 26, 27, 28) is arranged at an acute angle (W1) to the front wall (7) and / or to the rear wall (8), wherein the outlet nozzles (21, 22) have a jet cone (30) with a jet cone center axis (31) which is perpendicular to the funnel-shaped transition region (25, 26, 27, 28). [8] Screening machine (1) according to one of claims 1 to 7, characterized by that jet cone center axes (31) of several outlet nozzles (32, 22) arranged in pairs on the feed unit (9) and / or the outlet unit (10) and / or on the flange units (32, 33) intersect in the region of a vertical center longitudinal plane (MLE) of the screen housing (2). [9] Screening machine (1) according to one of claims 1 to 8, characterized by that several extinguishing agent containers (11, 12, 13, 14) are arranged point-symmetrically on the upper wall (3) of the sieve housing (2). [10] Screening machine (1) according to one of claims 1 to 9, characterized by that the explosion suppression system (34) is arranged point-symmetrically overall.

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