Shut-off valve with bypass device

Description

[0001] The subject matter of the invention is a combination of a conveying line with a gate valve with a bypass device for the conveying line for the pneumatic conveying of bulk materials according to the preamble of patent claim 1.

[0002] A gate valve is used to completely open or close the entire flow cross-section of a conveying line for the pneumatic conveying of bulk materials. Gate valves also serve as a pre-blocking device to prevent a conveying medium from flowing through it and simultaneously empty the conveying line before the suction process is completed.

[0003] In plastics processing, the principle of pneumatic conveying is used, whereby the material is transported through a conveyor line using air. Material transport is usually achieved using negative pressure (vacuum conveying), with the material being bulk materials such as granules, pellets, powder, regrind, flakes, or fibers.

[0004] A slide valve, which is driven longitudinally within the gate valve, closes and opens the flow cross-section of the conveyor line as a shut-off body, whereby a linear guide of the slide valve on both sides is necessary in order to guide it without jamming.

[0005] Due to the pressure in the conveying line, high forces are required to open and close the gate valve, which are generated by a drive mechanism. A smaller shut-off valve can be used to reduce the static pressure, opening a bypass around the gate valve itself.

[0006] Such a bypass can also be used to allow a bypass air stream to flow through the conveying line downstream of the closed valve when the valve is closed. This purge air stream can then, for example, clean the conveying line of bulk materials.

[0007] There are various types of gate valves; in plant engineering, so-called bulk material gate valves are used to shut off all types of bulk materials. In process engineering, bulk material gate valves are used to safely shut off and meter dry, free-flowing bulk materials, free-flowing powders, and granules.

[0008] Bulk material gate valves are differentiated by their actuation type and shape. Gate valves are available with square, rectangular, and round openings.

[0009] Known gate valves, such as those disclosed in EP 3 505 321 A1, for shutting off a conveyor line carrying bulk material, are characterized by a gate valve housing that surrounds sections of the conveyor line, as well as a gate valve mounted movably within the gate valve housing perpendicular to the conveyor line for temporarily shutting off the conveyor line. This gate valve has a through-opening that, when aligned with the conveyor line, allows maximum throughput of the conveyed material. The gate valve housing can be connected to a bypass for airtight sealing. The bypass can be used to drain the section of the conveyor line leading from the gate valve when the conveyor line is shut off.

[0010] The gate valve is operated by a pneumatic cylinder or a geared motor as the drive mechanism. Due to the high temperatures prevailing, a relatively thick gate plate is usually used to minimize deformation and expansion at high temperatures. With thinner gate plates, there is a risk that they will jam in the housing guide and block. This risk also exists if the gate valve also controls the bypass air supply. In this case, because the end face is adapted to this conveying situation, an increased plate thickness is required in order to effectively redirect the bypass air into the conveying line to drain it. Due to the large design, the drive mechanism must also apply more force to operate the gate valve. In addition, the necessary greater plate thickness of the gate plate requires an increased overall height of the entire gate valve.

[0011] The invention is therefore based on the object of further developing a gate valve for the pneumatic conveying of airworthy bulk materials for shutting off a conveying line with a bypass device of the type mentioned at the outset in such a way that, taking into account a simple control and supply of the bypass air, a gate valve which is as flat and non-blocking as possible is provided, which can generate a highly effective flushing air flow.

[0012] The object is achieved according to the invention by the features of the independent patent claim, while advantageous embodiments and further developments of the invention can be found in the subclaims.

[0013] In order to shut off and empty the conveying line, the valve housing is connected in an airtight manner to a bypass device on the housing side, through which a bypass air flow is sucked into the part of the conveying line leading out of the gate valve when the conveying line is shut off.

[0014] The housing-side bypass device is designed as a separate purge air housing, which is mounted next to the slide valve housing in the conveying direction, in the interior of which the discharge conveying line is routed.

[0015] The spatial separation of the purge air housing and the gate valve body allows for a thinner gate valve design. This reduces the overall height of the gate valve. Furthermore, the gate valve can operate at higher temperatures, and the gate valve exhibits lower material expansion and is less prone to jamming at higher temperatures.

[0016] The purge air housing of the bypass device is preferably mounted below the slide housing in the conveying direction, through whose interior the discharge conveying line is routed. The air-conducting openings according to the invention, which are incorporated in the casing of the discharge conveying line, are also located within the interior. The purge air housing is preferably cuboid-shaped and hollow. The separate arrangement of the purge air housing, which is spatially separated from the slide housing, results in the advantage of favorable air flow guidance of the bypass air flow in conjunction with a large ventilation cross-section and optimal slide guidance.

[0017] The plate-shaped gate valve has two different areas for controlling the flow of the conveyed flow or bypass air through the purge air housing. This is a blocking area formed by the front of the plate-shaped gate valve, which blocks either the bypass air supply or the conveyed medium from the purge air housing. In addition, the gate valve has a through-opening adapted to the pipe diameter. When congruent with the conveying line, this opening enables a virtually turbulence- and obstruction-free flow when the conveyed medium passes through the open gate valve.

[0018] If the gate valve is inserted with its through hole into the connection area between the discharge and supply lines, and this through hole is congruent with the supply and discharge lines, a nearly straight through pipe is formed. However, if the gate valve and thus the connection area are open, the gate valve is virtually vacuum-tight. This means that the vacuum in the line does not draw in any external air.

[0019] To ensure effective, full-surface shutoff of the flow cross-section of the conveying line, the conveying line is split within the gate valve, with either the through hole or the gate valve's blocking area being inserted into the connecting area. The blocking area serves to completely close the conveying line. This prevents further flow of conveyed medium through the conveying line. The now retracted blocking area no longer closes the opening in the side plate of the gate valve housing, allowing bypass air to flow into the purge air housing.

[0020] The general term "conveying line" refers to the conveying line composed of at least two individual conveying lines, whereby the conveying lines are connected to each other in an airtight manner within the gate valve in the connecting area and consist of a conveying line supplying the gate valve and a conveying line leading away from the gate valve, which are separated from each other by the gate valve inserted into the connecting area.

[0021] When the gate valve closes the connection area, the vacuum seal of the gate valve is released and the bypass device is activated. Due to the negative pressure in the conveying line, bypass air can now be drawn through a filter into the purge air housing, which surrounds the conveying line downstream of the gate valve, and flow into the conveying line through the air-conducting openings.

[0022] According to the invention, the discharge conveyor line has air-conducting openings incorporated into the cylindrical wall of the purge air housing, which allow bypass air to flow into the conveyor line. The purge air housing connects the bypass air inlet and the air-conducting openings in an air-conducting manner. The openings, distributed around the circumference, achieve the largest possible cross-section through which the bypass air can flow, thus optimizing the emptying suction performance.

[0023] Preferably, these are slots aligned longitudinally, although the invention is not limited to the use of slots. Any other shape of opening can also be used, provided they allow the inflow of bypass air. This can, for example, also be a plurality of holes in the casing of the conveying line or differently arranged slots or recesses that are not aligned longitudinally. Depending on the type of material to be conveyed, the size of the openings is selected so that they are smaller than the diameter of the material being conveyed. This prevents deposits of the material being conveyed in the openings during the conveying process.

[0024] The supply and discharge conveyor lines can have different diameters and the size of the air-conducting openings in the bypass can be adapted to the diameter of the material being conveyed.

[0025] The discharge conveyor line has a collar-like flange below the air-conducting openings, with which the conveyor line is screwed to the purge air housing.

[0026] For the sake of simplicity, the following description assumes that the bypass device has slots as air-guiding openings, although the invention is not limited thereto.

[0027] The bypass air sucked in through the slots due to the negative pressure in the conveyor line can now remove the remaining material and flush the conveyor line.

[0028] The term "bypass air" refers to either ambient air, air enriched with substances, or other processed air that is fed into the conveying line via the bypass device. This can be, for example, dried air, nitrogen-enriched air, or air from another environment.

[0029] The present invention is not limited to the use of a filter for the controlled supply of bypass air. A strainer may also be used, although for the sake of simplicity, only the use of a filter will be described below. Instead of a filter or strainer, an additional pipe for supplying air can also be connected via a connecting piece.

[0030] Preferably, the filter and the supply line have an external thread with which they can be screwed onto and / or into the valve body. Such a thread arrangement also makes it possible to adjust the screw-in depth of the filter or strainer into the valve body. Screw rings are preferably used, which can only be loosened with a suitable tool to remove the filter or strainer. The screw-in depth can be determined and limited using spacer rings, which can also be pushed onto the threaded area.

[0031] The plate-shaped slide valve has a through hole, a blocking area located in front of it, and a push rod mounted behind it, to which the drive mechanism engages. If the flat blocking area is located in the connection area between the two conveying lines, no flow of the conveyed material is possible. In this position, an airtight connection exists between the filter and the discharge conveying line, which continues below the slide valve housing.

[0032] In this slide position, bypass air can now be sucked into the filter and flows from there into the purge air housing and from there via the air-guiding openings into the conveying line.

[0033] The side plate of the slide housing arranged below the slide in the conveying direction has an opening for the passage of the bypass air flow and a through opening for the passage of the conveying medium and both openings are connected to the purge air housing mounted on this side of the slide housing.

[0034] When the slide is pulled into the locked position, it is also pulled in the conveying direction by the negative pressure. This additionally seals the conveying line.

[0035] For example, a throughput of 120 to 600 m3 of bypass air per hour is preferred.

[0036] For example, the conveyor line may preferably have a diameter between 38 and 90 mm.

[0037] The conveyor line and its components are made of stainless steel, while the housings are made of aluminum. The gate valve is preferably made of plastic, which allows for tilt-free guidance within the gate valve housing.

[0038] The subject matter of the present invention results not only from the subject matter of the individual patent claims, but also from the combination of the individual patent claims with one another.

[0039] All information and features disclosed in the documents, including the abstract, in particular the spatial configuration depicted in the drawings, could be claimed as essential to the invention, insofar as they are novel, individually or in combination, compared to the prior art. The use of the terms "essential" or "according to the invention" or "essential to the invention" is subjective and does not imply that the features so named must necessarily be part of one or more patent claims.

[0040] The invention is explained in more detail below with reference to drawings illustrating only one embodiment. Further essential features and advantages of the invention will become apparent from the drawings and their description.

[0041] They show: Figure 1 : a schematic view of an open gate valve according to the state of the art Figure 2: a schematic view of a closed gate valve according to the state of the art Figure 3 : a perspective view illustrating aspects of the present invention Figure 4 : another perspective view of the invention Figure 5 : an exploded view according to the present invention

[0042] Figure 1 shows a gate valve 1 according to the prior art, with a bypass device 2', which is attached to a conveying line 3, 13. The conveying line is divided into a conveying line 3 leading into the housing and a conveying line 13 leading out of the valve housing 27'.

[0043] Inside the valve housing 27, a valve 22' is mounted for longitudinal movement and can be actuated by a drive mechanism 40. The valve 22' has a through hole 31' through which, when aligned with the conveying line 3, the material to be conveyed can flow unhindered in the direction of arrow 33.

[0044] A filter 17 is attached to the valve housing 27', which filters the air flowing in from outside. In the example shown, Figure 1 However, the air flow between filter 17 and the conveying line 13 leading from the slide housing is blocked by the slide 22', so that no air can flow from outside into the conveying line 13.

[0045] In Figure 2The slide 22' was pulled by the drive mechanism 40 in the direction of arrow 41. The through hole 31' is now no longer congruent with the conveyor line 3, 13 and is also shifted in the direction of arrow 41. Now the blocking area 24' of the slide 22' is pushed into the conveyor line and closes it.

[0046] By moving the slide 22' in the direction of arrow 41, the inclined surface 12, which is located below the blocking area 24', is also pulled in the direction of the conveying line until it forms a passage between the slide housing 27 and the conveying line 13 at the level of the conveying line 13.

[0047] Since the negative pressure prevailing in the conveying line 13 also acts on the airtightly connected slide valve housing 27, ambient air is drawn through the filter 17 in the direction of arrow 34. The ambient air flows through the slide valve housing 27' in the flow direction 35 and is drawn into the conveying line 13, allowing deposits in the conveying line to be removed. Since the slide valve housing 27' is an integral part of the housing of the gate valve 1, this results in an undesirably large overall height for the overall structure. This is where the invention, as shown in the following figures, comes into play.

[0048] Figure 3 shows the gate valve 1 according to the invention, which differs from the prior art in particular by the conveying line 13. The conveying line 13 has slots 14 distributed around the circumference, which extend in the longitudinal direction of the conveying line 13.

[0049] It is preferred if the housing-side bypass device 2 is designed as a purge air housing 20, which is mounted in the conveying direction next to the slide housing 27, in the interior 21 of which the discharge conveying line 13 is guided.

[0050] The combined conveying line 3, 13, which is formed in at least two parts, consists mainly of the conveying line 3 leading to the slide housing 27 and a conveying line 13 leading away from the housing 27. Both conveying lines are connected to each other in an air-conducting manner via a connecting area 47 inside the slide housing 20. The connecting area is particularly Figure 5visible. This connecting area 47 connects the mutually spaced ends of the conveying lines 3, 13, forming a straight pipeline. The through hole 31 of the slide 22 continues below the conveying line 3, with the same inner diameter, and below it the collar 7 of the sleeve 6, whereby the collar 7 also has the same inner diameter as the conveying line 3 and also as the conveying line 13 adjoining the collar 7.

[0051] In the example shown, the conveyor line 3 has Figure 3 at its lower area closest to the housing via an external thread 4. With the external thread 4, the delivery line 3 can be connected to the slide housing 27 via a screw ring 5, wherein the external thread 4 continues into the through hole 30 of the side plate 28, in which the delivery line 3 is received in the slide housing 27.

[0052] Below the connecting area 47, the sleeve 6 is inserted into the through-opening 23 in the side plate 29 of the valve body 27, which is connected to the side plate 29. The sleeve 6 has the collar 7, with which it rests against the inner circumference of the through-opening 23. In the flow direction below the collar 7, the sleeve 6 expands radially and forms the collar 8. On the inner circumference of the collar 8 is a circular shoulder 9, which serves to accommodate the end face 10 of the conveying line 13. This allows the conveying line 13 to be secured in position.

[0053] In addition to the through-opening 23, the side plate 29 has a further opening 42, which is arranged in the area of ​​the filter 17 and allows an inflow of bypass air into the interior 21. Initially, this opening 42 is according to Figure 3closed by the slide 22, whose blocking area 24 covers the opening 42 and rests on a projection 25 at the edge of the opening 42. Thus, no bypass air can flow from the filter 17 into the interior 21.

[0054] The plate-shaped slide 22 thus has two essential areas. First, the through-hole 31, which, when aligned with the conveying line, allows the conveying medium to flow through, and second, the blocking area 24, which is arranged in front of the through-hole 31 and optionally blocks the connection area between the conveying lines 3, 13 or the opening 42 of the bypass device 2 or the side plate 29 above the purge air housing 20.

[0055] The side plate 29 has a frame 15 extending toward the side plate 28, on which the side plate 28 rests and which extends around the edge of the side plate 29. Due to the frame 15, a chamber is formed between the spaced-apart side plates 28, 29, within which the slide 22 moves in the longitudinal direction. This frame 15 is open toward the drive mechanism 40 in such a way that the push rod 38 can pass through.

[0056] To actuate the slide 22, it has a lateral borehole 37 into which a push rod 38 is screwed, which can be pulled in the direction of arrow 41 via a drive mechanism 40 (not shown in detail).

[0057] In Figure 4the slide 22 is pulled in the direction of arrow 41 and the blocking area 24 no longer covers the opening 42. It is located between the conveyor lines 3, 13 and separates them from each other. Any material flowing in the conveyor line 3 impacts the upper side 25 of the blocking area 24 of the slide 22. However, since the negative pressure prevailing in the entire conveyor line is also interrupted or redirected by the slide 22, no more material is sucked in through the conveyor line 13 in the direction of arrow 33.

[0058] The through opening 23 is now located between the parallel side plates 28, 29 and no longer allows any flow.

[0059] By pulling the slide 22 in the direction of arrow 41, the blocking area 24 of the slide 22 has shifted from the opening 42 to the delivery line 3, 13, where it is located in the connecting area 47. The opening 42 is now open and allows air to pass through. The negative pressure still prevailing in the delivery line 13 draws in bypass air through the opening 42, which is then drawn into the delivery line 13 via the purge air housing 20. This is represented by the flow direction 35.

[0060] For this purpose, the conveying line 13 has a plurality of slots 14 on its pipe section 43 projecting into the purge air housing, which slots extend longitudinally in the example shown here. The bypass air drawn in due to the negative pressure thus flows through the slots 14 and into the conveying line 13. Advantageously, the bypass air can flow into the conveying line 13 over the entire circumference of the conveying line, i.e., 360°, due to the circular arrangement of the slots 14.

[0061] Above the opening 42 is the filter 17 fastened to the side plate 28, through which bypass air is sucked into the bypass device 2 in the direction of arrow 34 due to negative pressure. After passing the filter 17, the bypass air flows through the opening 24 opened by the slide 22 in the flow direction 35 into the interior 21 of the purge air housing 20 and further through the slots 14 into the conveyor line 13 projecting into the purge air housing 20. Since the slots 14 of the conveyor line are distributed over the entire circumference of the conveyor line in this area, the bypass air can also flow into the conveyor line 13 from all sides, i.e. over a circumference of 360°.

[0062] The delivery line 13 has a flange 11 with which it rests against the outside of the base 44 of the purge air housing 20 and can be fastened, with screw fastening being preferred. The flange 11 is attached in a collar-like manner to the outer circumference of the delivery line 13. The delivery line 13, starting from the flange in the direction of the purge air housing, continues tubularly as a pipe section 43 and only has the slots 14 in the upper region, which is inserted into the housing 20. The delivery line 13 rests with its end face 11 against the shoulder 9 of the sleeve 6.

[0063] Figure 5shows an exploded view of the gate valve 1, with the delivery line 13, which has the collar-like flange 11, with which it can be screwed to the underside of the base 44 of the purge air housing 20. For this purpose, the purge air housing 20 in the example shown has four threaded holes 45, into which screws 46, passing through the flange 11, can engage and be screwed.

[0064] Above the flange 11, the conveyor line 13 continues with the pipe section 43 which is connected to it in one piece and in whose casing 16 the slots 14 are made.

[0065] If the flange 11 is screwed to the base 44, the pipe section 43 projects into the interior of the purge air housing 20 and the end face 10 comes into contact with the inner, circular shoulder 9 of the sleeve 6. The sleeve 6 is screwed into the side plate 29 and, thanks to its collar 7 adapted to the diameter of the conveying line 3, 13, enables an air-tight conveying path between the conveying lines 3 and 13.

[0066] The connection area 47 is the distance between the conveying line 3 and the conveying line 13, in which the sleeve 6 and through opening 23 allow the conveyed material 32 to flow through when the slide 20 is open.

[0067] The purge air housing 20, which is placed on the side plate 29, forms a cavity or interior space 21, in the interior of which the pipe section 43 of the conveying line 13 is arranged. This allows the sucked-in bypass air to be sucked through all the slots 14 into the interior of the conveying line 13. The bypass air flows beforehand via the opening 42 into the interior space 21 of the purge air housing 20. The slide valve 22, which is displaceably mounted in the slide valve housing 27, selectively opens and closes the opening 42 or the connecting area 47 and thus alternates between an uninterrupted flow of the conveyed material 32 in the direction of arrow 33 through the air-tight and aligned interconnected conveying lines 13, 33, or a flow of bypass air, which is sucked via the filter 17 into the purge air housing 20 and then via the slots 14 into the conveying line 13 in the flow direction 35. Drawing legend

[0068] 1 Gate valve 2, 2'Bypass device 3 Delivery line (feeding) 4 External thread 5 Screw ring 6 Socket 7 Collar 8 Collar 9 Shoulder 10 End face (of 48) 11 Flange 12 Inclined surface 13 Delivery line 14 Opening 15 Frame 16 Shell 17 Filter 18 External thread 19 Spacer ring 20 Purge air housing 21, 21' Interior 22, 22' Valve 23 Through opening (of 29) 24, 24' Restricted area 25 Projection 26 Top 27, 27' Valve housing 28 Side plate 29 Side plate 30 Through hole (of 28) 31, 31' Through hole (of 22) 32 Conveyed material 33Arrow direction 34Arrow direction 35Flow direction (bypass air) 36 37Bore hole 38Push rod 39Plain bearing 40Drive mechanism 41Arrow direction 42Opening (of 29) 43Pipe section (of 13) 44Bottom (of 20) 45Threaded hole 46Screw 47Connection area

Claims

1. Combination of a gate valve (1) and a conveying line (3, 13) for pneumatic conveying of bulk goods to isolate the conveying line (3, 13), comprising a slide housing (27) with a slide (22, 22') mounted displaceably in the slide housing (27) for temporary isolation of the conveying line (3, 13), wherein as a function of the position of the slide (22, 22'), an air-tight passage through the slide housing (27) or flushing of the discharging conveying line (3, 13) connected in air-tight manner to the slide housing (27) is provided, wherein to isolate and draw empty the conveying line (3, 13), the slide housing (27) is connected in air-tight manner to a bypass device (2, 2') arranged separately, though which a bypass air stream is drawn into the part of the conveying line (13) discharging from the gate valve (1) when isolating the conveying line (3), and wherein the bypass device (2) configured separately is configured as a flushing air housing (20) which is mounted next to the slide housing (27) in conveying direction, in the interior (21) of which the discharging conveying line (13) is guided, characterised in that a cylindrical jacket (16) of the discharging conveying line (13) has within the gate valve several air-guiding openings (14) to initiate the bypass air stream.

2. Combination according to claim 1, characterised in that the air-guiding openings (14) are located within the interior (21).

3. Combination according to claim 1 or 2, characterised in that the flushing air housing (20) connects the bypass air inlet (17) and the air-guiding openings (14) in air-guiding manner.

4. Combination according to one of claims 1 to 3, characterised in that the bypass air inlet is a filter (17), a screen, a connection or a supply pipe.

5. Combination according to one of claims 1 to 4, characterised in that the air-guiding openings (14) are slots or holes in the jacket (16) of the conveying line (13).

6. Combination according to one of claims 1 to 5, characterised in that the side plate (29) of the slide housing (27) arranged below the slide (22) in conveying direction has an opening (42) for conducting the bypass air stream and a passage opening (23) for conducting the conveying medium and the opening (42) and the passage opening (23) lead into the interior (21) of the flushing air housing (20) mounted on this side of the slide housing (27).

7. Combination according to one of claims 1 to 6, characterised in that the discharging conveying line (13) can be replaced.

8. Combination according to one of claims 1 to 7, characterised in that the discharging conveying line (13) below the air-guiding openings (14) has a collar-like flange, with which the conveying line (13) is screwed onto the flushing air housing (20).

9. Combination according to one of claims 1 to 8, characterised in that the plate-like slide (22) has a passage hole (31) which facilitates throughput of the conveying medium (32) when aligning with the conveying line (3, 13) and has an isolating region (24) which is arranged upstream of the passage hole (31) in longitudinal direction and which optionally closes a connecting region (47) between the conveying lines (3, 13) or the opening (42) of the bypass device (2) at the entrance to the flushing air housing (20).