Explosion protection valve

Abstract

Explosion protection valve (1) for protecting a mill, a classifier and / or other plant handling flammable fine dust and / or gas, comprising a valve housing (2) with two connecting flanges (3) between which a movable valve body (4) with a valve stem (4a) and a valve disc (4b) is positioned, wherein the movable valve body (4) is designed and mounted in such a way that the explosion protection valve (1) is permanently and completely closed by the pressure wave preceding the flame front in the event of an explosion in the plant area protected by the explosion protection valve (1), characterized in that the valve disc (4b) has a circumferential recess (4c) on its side facing the protected plant area, extending around the valve stem area.

Description

[0001] The invention relates to an explosion protection valve according to the preamble of claim 1. TECHNICAL BACKGROUND

[0002] Explosion protection valves are solutions for decoupling explosions and are used as part of structural explosion protection. This measure becomes necessary when preventive protective measures, such as ignition source-free environments, are no longer sufficient to guarantee adequate protection. Various types of explosion protection valves are used in systems that are interconnected by pipelines. In the event of an explosion, the propagation of flames or pressure waves to adjacent system components is effectively prevented by the explosion protection valve sealing the pipeline.

[0003] These types of decoupling valves (e.g., Ventex) are primarily used in areas where flammable dusts, gases, or hybrid mixtures are processed. Such applications are common in the pharmaceutical industry, chemical / petrochemical companies, food and feed production, and research laboratories. A distinction is usually made between active and passive explosion protection valves.

[0004] Passive explosion protection valves function without external power or control; they react solely to the effects of an explosion and, due to their design, prevent flame and pressure propagation within pipelines and into adjacent plant components. Active explosion protection valves, on the other hand, require external power and a control system to close the pipeline. They use sensors that react to pressure increases or flames to detect the explosion and then immediately trigger countermeasures, i.e., the closure of the valve.

[0005] As a first approximation, it can be said that the smaller the maximum nominal diameter is to be, the more difficult it becomes to build truly reliably closing passive explosion protection valves. THE TASK UNDERLYING THE INVENTION

[0006] Accordingly, the object of the invention is to provide an explosion protection valve which has a further improved response behavior in the event of an explosion. INVENTIONAL SOLUTION

[0007] An explosion protection valve is proposed for the protection of a mill, a classifier, and / or other equipment handling flammable fine dust and / or gas, designed as described below. This explosion protection valve comprises a valve body with two connection flanges, between which a movable valve body is positioned. The valve body comprises a valve stem and a valve disc. The valve body need not be an integral, one-piece component and preferably consists of at least two different components. The valve disc is preferably mounted on the valve stem, which is preferably at least three, and preferably at least five, times as long as the axial extent of the valve disc.

[0008] The movable valve body is designed and mounted in such a way that, in the event of an explosion in the plant area protected by the explosion protection valve, the pressure wave preceding the flame front permanently and completely closes the explosion protection valve.

[0009] The explosion protection valve according to the invention is characterized in that the valve disc has a recess on its side facing the protected area of ​​the system in the flow direction, which circumferentially surrounds the valve stem completely or substantially completely. The recess is thus preferably at least 90%, and particularly preferably at least 95%, circumferential. The particularly preferred embodiment features a completely circumferential recess without interruption.

[0010] The recess thus surrounds the valve stem in the circumferential direction, whereby the recess can touch the valve stem or preferably has a radial distance from the valve stem.

[0011] Thanks to its indentation, the valve disc creates a "parachute effect". The pressure wave preceding the flame front becomes trapped in the indentation, like in a parachute, thereby generating an increased closing force that permanently closes the valve body or moves it into a permanently closed position.

[0012] The valve disc is also referred to as the "runner" in the following. It preferably has a parachute-like shape in order to capture the pressure wave preceding the flame front in such a way that it does not simply pass by the runner, but rather transfers its momentum to the runner as much as possible in order to push the runner into the closed position as quickly as possible.

[0013] The rotor is preferably made of plastic to minimize its inertia and thus achieve the fastest and most sensitive valve response possible. A plastic rotor is feasible because the valve disc is not, or only minimally, exposed to any flames. This is because the valve closes so early that a pressure cushion of the gas preceding the explosion or its flame front builds up directly in front of the valve, and this pressure cushion stops the flame front a distance from the rotor. However, a rotor made of a different material is also possible in many cases, preferably aluminum or titanium.

[0014] In this way, a simple mechanism for a passive explosion protection valve can be provided, which reacts faster than before when an explosion-typical pressure wave arrives, usually preceding the flame front, and is therefore particularly attractive for systems with pipes of nominal diameters below DN100.

[0015] "Completely closed" within the meaning of the invention means that the valve is in a state in which it offers no passage whatsoever for gases or vapors, or at least prevents the passage of the flame front, even if a negligible amount of gas may pass through. This means that the valve is designed in such a way that, in the closed state, it ensures a seal sufficient to prevent the escape of hazardous substances and / or to prevent the propagation of the flame front, thereby minimizing the risk of an explosion, or at least of an uncontrollable explosion.

[0016] In the context of the invention, "permanent" means that the completely closed state cannot be opened without tools. Even after the air in the secured container has cooled and overpressure has built up, the closed state must not be opened to prevent any potential embers from reigniting. However, this "permanent" seal can be reversibly opened using tools. FURTHER EDUCATION OPPORTUNITIES IN INVENTION

[0017] A preferred further development of the explosion protection valve involves limiting the aforementioned recess with a valve disc rim ring whose height – measured from the deepest point of the recess – is at least one-third of the axial extent of the actual valve disc. The recess is thus bounded radially outward by a ring that preferably also forms the rim of the valve disc. The height of the recess is its greatest axial extent – ​​preferably parallel to the central axis of the valve disc. The axial position of the valve disc is also its greatest axial extent – ​​disregarding any attached components such as a clamping sleeve. This recess design contributes to the aforementioned "parachute effect" and enables better force generation on the valve disc by the pressure wave.

[0018] Furthermore, it is particularly preferred if the valve head rim ring has a circular cylindrical shape on its inner circumferential surface. The side of the valve head rim ring facing the recess is thus preferably a circumferential cylindrical surface. Moreover, the entire recess preferably has a substantially circular cylindrical shape. This contributes to the necessary parachute effect and is also a simple, easy-to-manufacture, and cost-effective embodiment.

[0019] Furthermore, it is particularly preferred if a loose reducing ring, i.e., one that can be removed after opening the valve housing – preferably entirely without tools – is inserted into the valve housing. This reducing ring defines the maximum height of the narrowest section of the gap through which the valve disc is passed by the pressure wave, or part thereof, preceding the flame front in the event of an explosion. This reducing ring preferably extends at least partially around the valve disc, and in particular around the valve disc's rim ring, at least in the fully open position. The degree of resistance that the valve disc offers to the pressure surge can be easily adjusted via this reducing ring. The smaller the gap, the more force is exerted directly on the valve disc by the pressure wave and cannot bypass it.

[0020] Furthermore, it is particularly preferred if the outer surface of the valve disc, in the area where it forms the gap through which the pressure wave or part of the pressure wave preceding the flame front passes directly in the event of an explosion, is predominantly or substantially completely convexly curved. This results in advantageous flow guidance of the pressure wave and prevents possible unwanted backflows due to vortex formation.

[0021] Furthermore, it is particularly preferred if the valve stem is equipped with an axially acting valve stem brake on at least one side, which influences the magnitude of the force required to move the movable valve body in the closing direction. This valve stem brake prevents harmless pressure surges occurring during operation from triggering the valve. These surges include, for example, compressed air surges such as those that occur when purging a filter. The explosion protection valve according to the invention preferably allows the process gas of the system to pass through in both directions (intake and exhaust air), but does not trigger in the event of system-specific pressure fluctuations. Preferably, in the event of an explosion within the system, the explosion protection valve seals hermetically up to a pressure of preferably 10 bar, particularly preferably 15 bar and 0.8 bar absolute, with the first pressure wave before flames reach the valve. Thus, no flames or product components escape to the outside.Preferably, a sensor in the control system also reports the activation of the valve.

[0022] Furthermore, it is particularly advantageous if the valve stem brake includes a conical section to which at least one pressure piece acts, at least temporarily, tending to push the valve stem in the opening direction. This provides an additional, simple way to ensure that even strong, but harmless, pressure surges do not permanently close the valve, but at best move it a little further, from where the valve then falls back into the open position. The valve's response can be adjusted by the slope of the conical section of the valve stem brake. If the cone is shallower, the rotor responds sooner and is more easily forced into its closed position. If the cone is steeper, greater forces are required to push the rotor into its closed position.

[0023] The cone also serves to hold the runner in its unactivated position, because the valve stem on which the runner sits is held at its stop by the conical section. This provides the runner with a degree of fixation in its open position, which can only be overcome when the forces acting on the runner are so great that at least one pressure piece moves up the cone. This conical section therefore serves, at least partially, as a brake.

[0024] Furthermore, it is particularly preferred if the conical section in the closing direction is followed by a cylindrical section along which the at least one pressure piece can travel as the valve continues to close, without any further tendency to push the valve stem in the opening direction. Even after the conical section has been traversed, the valve preferably should not yet fully engage in the closed position. The pressure piece preferably first passes over the cylindrical section, which serves as an acceleration path.

[0025] Another preferred embodiment consists of a detent device following the conical and / or cylindrical section in the closing direction, ideally in the form of a groove in the valve stem, by means of which the explosion protection valve can be held in its closed position. After passing through the conical and cylindrical sections, the valve must therefore remain permanently closed, since a triggering force, intended to be a pressure wave, necessitates the valve's closure. In this way, the valve is reliably kept closed after triggering, even if a vacuum subsequently develops in the explosion area due to cooling, and the system then tends to draw air in through the valve.However, this reopening of the valve by suction is undesirable in order to prevent any embers from being fed by re-inflowing oxygen or from embers even escaping past the valve plate to the outside.

[0026] Furthermore, it is particularly preferred if the at least one pressure piece is a spring-loaded pressure piece which preferably includes a ball on its end face facing the housing. Such pressure pieces are standardized. In this way, a reliable locking device can be created in a simple and cost-effective manner.

[0027] Further modes of operation, advantages and design possibilities result from the figure-based description of the exemplary embodiment. LIST OF FIGURES The Fig. Figure 1 shows an exploded view of the explosion protection valve according to the invention in a cutaway side view. The Fig. Figure 2 shows the explosion protection valve according to the invention in a cutaway side view in a fully open position. The Fig. Figure 3 shows the explosion protection valve according to the invention in a cutaway side view in a fully closed position. The Fig. Figure 4 shows the explosion protection valve according to the invention in a cutaway side view in a fully open position and with tools inserted to release the closed state. The Fig. Figure 5 shows a detailed view of a pressure piece with an initiator and the surroundings of the pressure piece of the open explosion protection valve in a cutaway side view. PREFERRED EXAMPLE OF EXECUTION

[0028] The Fig. 1 to Fig. Figure 5 shows a preferred embodiment of the explosion protection valve 1 according to the invention.

[0029] The explosion protection valve 1 (or simply: valve 1) comprises a valve housing 2, which preferably consists of a first housing half 2a and a second housing half 2b, ideally held together by a clamp 10, which is preferably designed to be clampable and releasable. A circumferential housing seal 22 is preferably located between the two housing halves 2a and 2b. At both axial ends of the valve 1, the housing 2 preferably includes a connection flange 3. This allows the valve 1 to be positioned arbitrarily within a system; at the end of a pipeline, between two pipelines, etc. The housing 2 is preferably made of stainless steel and machined from solid material.

[0030] The first housing half 2a preferably houses an O-ring 11, with which a holder 12 preferably interacts. Both the O-ring 11 and the holder 12 are preferably held in a corresponding receptacle in the first housing half 2a, with the holder 12 being spring-loaded by the O-ring 11. The holder 12 is preferably formed by two concentric rings connected to each other via connecting webs. Preferably, three connecting webs are provided, which are preferably arranged in a star shape, so that the design of the holder 12 is reminiscent of a Mercedes star.

[0031] The holder 12 centrally accommodates a first bearing sleeve 13a, which acts as a flow divider on one side. This bearing sleeve 13a preferably has several central, axial bores, in which further parts of the valve 1 are accommodated. First, a sliding bearing 14 is preferably accommodated in the largest of these bores, in which the valve stem 4a is axially movably mounted. This valve stem 4a is preferably a hollow rod with an internal thread at each of its ends. A sealing screw 16 with a bore is preferably screwed into the end of the valve stem 4a that faces the first bearing sleeve 13a. A spacer rod 17 is inserted into the bore of the sealing screw 16 and is held in the smallest bore of the first bearing sleeve 13a. The valve stem 4a is inserted into another bore of the bearing sleeve 13a. This bore preferably acts as a shoulder to stop the valve stem 4a in its fully open position.

[0032] The first bearing sleeve 13a is preferably sealed axially in the direction of the valve plate 4b by a piston sealing ring 15, which lies between it and the valve stem 4a.

[0033] The valve disc 4b is parachute-shaped with a recess 4c and a valve disc rim ring 4d and is preferably supported by the valve stem 4a. For this purpose, the valve disc 4b preferably has a central, axial bore and is pushed onto the valve stem 4a. The valve disc 4b is preferably fastened to its shaft or the valve stem 4a by two retaining rings 18, one axially at each end of the valve disc 4b. The valve disc 4b also receives a clamping sleeve 20 axially on at least one side, which is secured axially on one side by one of the retaining rings 18. Preferably, a reducing ring 5 extends at least partially around the valve disc 4b, which is preferably inserted into the housing 2 and preferably held by the two housing halves.

[0034] In the second housing half 2b, a seal 23 is preferably held, which serves as a stop for the valve disc in the closed state (see Fig. 3) acts. The valve plate 4b is preferentially pressed against this by the pressure wave in the closed state.

[0035] The second housing half 2b preferably includes a second bearing sleeve 13b, which, analogous to the first bearing sleeve 13a, is also designed as a flow divider on one side. This second bearing sleeve 13b is preferably also sealed against the environment towards the valve disc 4b, preferably by means of a felt seal 21. The second bearing sleeve 13b also has several central, axial bores. The other end of the spacer rod 17 is received in one of these bores. A sliding bearing 14 is received in another bore, which in turn supports the valve stem 4a for axial displacement. A valve stem brake 8 is preferably screwed into one axial end of the valve stem 4a. This brake preferably comprises a conical section 8a, a cylindrical section 8b, and a detent device 8c, which is preferably designed in the form of a circumferential groove. These sections are preferably overridden by pressure pieces 9.

[0036] These pressure pieces 9 are preferably also the retaining elements of the second bearing sleeve 13b. The valve 1 preferably has three pressure pieces 9, which are preferably distributed around the circumference in a star shape.

[0037] The second bearing sleeve 13b also accommodates the valve stem brake 8 in one of its central bores and preferably forms a possible stop for the valve stem brake 8 on the inside.

[0038] The valve disc 4b, with its valve stem 4a, is thus axially movable within the two bearing sleeves 13a and 13b. In the event of an explosion, the pressure wave preceding the flames moves the valve disc 4b axially towards the seal 23, against which the valve disc 4b is pressed. During this movement, the individual sections of the valve stem brake 8 are traversed by the pressure piece(s) 9; first the conical section 8a, then the cylindrical section 8b, and once these sections have been traversed by sufficient force, the pressure pieces 9 engage in the detent device 8c (see Fig. 3).

[0039] A pressure piece 9 is preferably a spring-loaded pressure piece with a ball. Furthermore, the pressure piece preferably includes a head or a shoulder. Each pressure piece 9 is preferably received and held by a bearing holder 24. The bearing holder 24, together with the pressure piece 9, is inserted into a bore in the second housing half 2b. Preferably, the head or shoulder of the pressure piece rests in the inner bore of the bearing holder 24 (see figure). Fig. 2 and Fig. 3) The bearing holder 24 thus preferably extends through the second housing half 2b towards the second bearing sleeve 13b, where the bearing holder 24 preferably rests. The bearing holder 24 therefore functions as a holding device for the pressure piece 9.

[0040] To reset the valve 1 and thus release the locking mechanism, a tool 27 is screwed onto each pressure piece 9 (see Fig. 4) The plunger of the pressure piece 9 can be retracted from its detent position using the tool 27. To facilitate the release of all three pressure pieces 9, it is preferred that the pressure pieces 9 are held in their released position by means of a cotter pin 26. This allows a worker to release and hold each pressure piece 9 individually and to push the valve disc 4b back into its open position. After the cotter pins are released, the pressure pieces 9 engage the conical section 8a again and thus hold the valve 1 open, as explained above. The valve 1 is then back in its open starting position. The tool 27 preferably has a round diameter.

[0041] The Fig.Figure 5 shows a detailed view of a pressure piece 9 and the area surrounding the pressure piece 9 of the open explosion protection valve in a sectional side view. Here, it is clearly visible how the pressure piece 9 rests on the shoulder of the internal thread of the bearing holder 24. Furthermore, an initiator 28 is installed in the bearing holder 24 above the pressure piece. This initiator is preferably an inductive proximity switch. When the valve 1 is open and thus normal conditions prevail, the preferably initiator sends a signal to the control system. However, if an explosion occurs, which actuates the pressure piece, the pressure piece in turn actuates the initiator 28. After actuation of the initiator, the corresponding signal preferably remains absent, and this preferably leads to a shutdown of the system by the control system.

[0042] Preferably, at least one initiator 28 is installed on each valve 1.

[0043] Generally, it is preferred that the reducing ring 5 allows the response behavior of the valve 1 to be adjusted. If a strong pressure wave is expected, the corresponding gap 6 can be increased. If a weaker pressure wave is expected, the gap 6 can be decreased accordingly, and the valve 1 will respond earlier.

[0044] Pressure piece 9(s) can also be used to adjust the response of valve 1. Pressure piece 9 is also preferably used to adjust the system conditions or selected to match them. Possible system conditions include, for example, pulses originating from the filter or mill / separator, flows, poles, and other factors. REFERENCE MARK LIST 1 explosion protection valve 2 Valve housings 2a First half of the housing 2b Second half of the case 3 connection flange 4 valve bodies 4a Valve stem 4b Valve plate (runner) 4c Advanced 4d valve plate edge ring 5 reducing ring 6 columns 7 not assigned 8 Valve stem brake 8a Cone section 8b Cylindrical section 8c Locking device 9 printing piece 10 clamp (DIN32676) 11 O-ring 12 holders (star) 13a First bearing sleeve 13b Second bearing sleeve 14 plain bearings 15 Piston sealing ring 16. Sealing screw with bore 17 Spacer bar 18 retaining ring 19 O-ring 20 clamping sleeve 21 Felt seal 22 Housing seal 23 Seal (valve plate stop) 24 bearing holders 25 not assigned 26 Splint 27 tools 28 Initiator

Claims

[1] Explosion protection valve (1) for protecting a mill, a classifier and / or other plant handling flammable fine dust and / or gas, comprising a valve body (2) with two connection flanges (3) between which a movable valve body (4) with a valve stem (4a) and a valve disc (4b) is positioned, wherein the movable valve body (4) is designed and mounted in such a way that the explosion protection valve (1) is permanently and completely closed by the pressure wave preceding the flame front in the event of an explosion in the plant area protected by the explosion protection valve (1), characterized by , that the valve disc (4b) has a circumferential recess (4c) on its side facing the protected plant area, extending around the valve stem area. [2] Explosion protection valve (1) for protecting a mill, a classifier and / or any other system for handling flammable fine dust and / or gas according to claim 1, characterized by , that the recess (4c) is bounded by a valve disc rim ring (4d) whose height is at least 1 / 3 of the axial extent of the actual valve disc (4b). [3] Explosion protection valve (1) for protecting a mill, a classifier and / or any other plant handling flammable fine dust and / or gas according to claim 2, characterized by , that the valve disc rim ring (4d) has a circular cylindrical shape on its inner circumferential surface. [4] Explosion protection valve (1) for protecting a mill, a classifier and / or other plant handling flammable fine dust and / or gas, preferably according to one of the preceding claims, comprising a valve housing (2) with two connecting flanges (3) between which a movable valve body (4) with a valve disc (4b) is positioned, wherein the movable valve body (4) is designed and mounted such that the explosion protection valve (1) is permanently and completely closed by the pressure wave preceding the flame front in the event of an explosion in the plant area protected by the explosion protection valve (1), characterized by , that a loose reducing ring (5) is inserted into the valve housing (2), which defines the maximum height of the narrowest gap section of the gap (6) through which the valve disc (4b) is passed by the pressure wave preceding the flame front in the event of an explosion. [5] Explosion protection valve (1) for protecting a mill, a classifier and / or any other plant handling flammable fine dust and / or gas according to any of the preceding claims, characterized by , that the outer surface of the valve disc (4b) in the area where it forms the gap (6) through which the valve disc (4b) is directly passed by the pressure wave preceding the flame front in the event of an explosion is predominantly or substantially completely convexly curved. [6] Explosion protection valve (1) for protecting a mill, a classifier and / or other plant handling flammable fine dust and / or gas, comprising a valve housing (2) with two connecting flanges (3) between which a movable valve body (4) with a valve disc (4b) is positioned, wherein the movable valve body (4) is designed and mounted such that the explosion protection valve (1) is permanently and completely closed by the pressure wave preceding the flame front in the event of an explosion in the plant area protected by the explosion protection valve (1), preferably according to one of the preceding claims, characterized by , that the valve stem (4a) is associated at least on one side with an axially acting valve stem brake (8) which influences the magnitude of the force required to move the movable valve body (4) in the closing direction. [7] Explosion protection valve (1) for protecting a mill, a classifier and / or any other plant handling flammable fine dust and / or gas according to claim 6, characterized by , that the valve stem brake (8) comprises a conical section (8a) on which a pressure piece (9) acts at least temporarily, which has the tendency to push the valve stem (4a) in the opening direction. [8] Explosion protection valve (1) for protecting a mill, a classifier and / or any other plant handling flammable fine dust and / or gas according to one of claims 6 or 7, characterized by , that the conical section (8a) in the closing direction is followed by a cylindrical section (8b) which the at least one pressure piece (9) can run along in the course of further closing of the valve, without having any further tendency to push the valve stem (4a) in the opening direction. [9] Explosion protection valve (1) for protecting a mill, a classifier and / or any other plant handling flammable fine dust and / or gas according to any one of claims 6 to 8, characterized by , that a detent device (8c) follows the conical section (8a) and / or the cylindrical section (8b) in the closing direction, ideally in the form of a groove in the valve stem (4a), by means of which the explosion protection valve (1) can be held in its closed position. [10] Explosion protection valve (1) for protecting a mill, a classifier and / or any other system handling flammable fine dust and / or gas according to any one of claims 6 to 9, characterized by , that the at least one pressure piece (9) is a spring-loaded pressure piece which preferably comprises a ball on its end face facing the housing (2).

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