DE202020105005U1 - Process valve, device for monitoring a seal back space, and food processing or filling system - Google Patents

Abstract

Process valve (P), in particular for sterile process engineering when processing or filling liquid food products, with a housing (1) having a product space (5), in which the product space (5) opposite a rear seal space (13) communicating with the environment is formed by a Membrane or bellows seal (A), (12), (23) is separated in a liquid-tight manner, and with a device (V) for detecting at least one defect in the membrane or bellows seal (A), the device (V) measuring at least one level of moisture in Seal back space (13) detecting moisture sensor (15), characterized in that between the seal back space (13) and the environment a water vapor permeable but water-blocking membrane (16) is installed.

Description

The invention relates to a process valve according to the preamble of claim 1, a device according to the preamble of claim 12, and a food processing or filling system according to claim 13.

In aseptic process valves, the product is sealed off from the environment (atmosphere) by a membrane or bellows seal in the area of the valve stem leadthrough. The diaphragm or bellows seal is subject to wear due to the movement of a shut-off element of the process valve and external influences such as pressure peaks, which leads to crack formation and thus to a defect. This can lead to contamination or unsterility of the product. It is therefore known to detect a defect in the membrane or bellows seal in order to avoid contamination of the product (stopping the process and eliminating the defect), or alternatively to fill the seal back space with a sterile medium (overlay method) to prevent contamination .

Out U.S. 4,688,601 A and DE 9 116 465 U1 Known process valves are equipped with a device that includes a moisture sensor that detects the moisture in the seal back space and thus registers and reports a defect. As a rule, liquid food products contain water which, if the membrane or bellows seal is defective, enters the rear space of the seal and causes the humidity sensor to respond. Such process valves are usually used in wet environments, i.e. in food-producing companies regular external cleaning with water or a cleaning medium is common, whereby it cannot be avoided that, when the process valve is wet, the valve tappet during its movements due to the so-called elevator effect, water from the outside into the The seal back space drags and / or condensation occurs in the seal back space due to temperature differences. This water entry does not represent a defect in the membrane or bellows seal, but when using a humidity sensor it leads to unavoidable errors or incorrect measurements or incorrectly reported defects. This also applies to the process valve of the DE 9 116 465 U1 , although this process valve is equipped with an additional bellows seal in the area of the valve stem leadthrough. However, this sealing concept is so expensive that it has not yet been implemented commercially.

Are also of interest DE 4 419 487 B4 , EP 2 118 545 B1 , EP 0 945 658 B1 , EP 1 726 855 B1 , EP 1 097 330 B1 , US 794,595 B2 .

The invention is based on the object of specifying a process valve and a device for equipping a process valve, in particular for food processing or filling systems, with which the risk of incorrect measurements due to condensation in and the inevitable entry of external moisture from the environment into the seal back space is eliminated , and which are inexpensive and low-maintenance.

The object set is achieved with the features of claim 1, claim 12 and claim 13.

The membrane prevents liquids or water from entering the seal back space from the outside, but makes it possible, due to the movement of the valve tappet, to discharge liquids or condensation water entrained from the seal back space through evaporating discharge, so that incorrect measurements or unnecessary process interruptions are avoided. On the other hand, since the capacity of the membrane's vapor permeability is limited, a defect in the membrane or bellows seal is reliably and immediately registered, since in the event of a defect, liquid food products release so much water into the seal back space that the membrane is overwhelmed and the humidity sensor responds and the Reports the defect correctly.

The device is an inexpensive, even retrofittable equipment of such process valves, which avoids incorrect measurements and always enables correct defect signals.

This is particularly useful in food processing or filling plants, in which the inventive concept can avoid contamination of the product and incorrect measurements by stopping the process in good time.

The evaporation of the small amounts of liquid or water that are dragged in or result from condensation water is made possible in a simple and inexpensive way by the fact that the product or superheated steam or a hot cleaning medium for sterilizing the product space in the seal back space generates such a high temperature, permanently, or in some cases that the evaporation discharge is ensured to a sufficient extent.

In an expedient embodiment of the process valve, in which in the product space a closure member adjustable via a drivable plunger is provided, with the membrane or bellows seal sealing the plunger penetrating this air-containing seal back space from the product space, the humidity sensor can be operated with a lower selected response tolerance range and is operated with the membrane with a defect-free membrane and bellows seal in the seal back space from entrained or condensed water within the response tolerance range is set so that the humidity sensor does not provide a defect signal until a defect actually occurs. The response tolerance range is z. B. set depending on the temperature conditions, process cycles, product types and process valve sizes, the size (diameter) and / or capacity of the membrane is expediently selected accordingly in order to ensure correct defect detection with high reliability.

The membrane is expediently made of PTFE (trade name Gore-Tex), although other types of plastic can be used as an alternative, which guarantee water vapor permeability and prevent liquids from penetrating from the outside. The membrane can be reinforced with fabric or built in with a support structure.

It is also expedient if the plunger, which is guided from the housing to a drive, is sealed off from the environment in the housing by a dynamic seal. In the simplest case, this is at least one sliding seal, although at least one bellows or a membrane seal (liquid-tight and movable) could alternatively be provided.

Another important aspect of the invention is that between the seal back space and the environment in the direction of flow to the membrane in front of the membrane there is a non-return valve which blocks the seal back space in the flow direction. During the breathing movement of the diaphragm or bellows seal when the process valve is working, compressed air is displaced into the environment in order to relieve the diaphragm or bellows seal, whereas when the seal back space is reduced, no air is sucked in from the environment and therefore negative pressure is built up in the seal back space in the event of a defect, prevents air or moisture from entering the product area from the seal back space. Rather, product is then sucked into the seal rear space via the defect point, which at least temporarily ensures that there is no contamination of the product in the product space. This accompanying measure is expediently combined with the water vapor permeable membrane.

In addition, the membrane can be designed in such a way that it allows displaced air to escape and sucked-in air to flow in in a throttled manner in order to generate a desired negative pressure in the seal back space when the volume of the seal back space increases.

In an expedient embodiment, the humidity sensor is equipped with an integrated temperature sensor. This makes it possible to compensate for undesired temperature influences when the humidity sensor is working. The humidity sensor can be designed in such a way that it generates and emits the defect signal itself. Alternatively, the humidity sensor can be linked to a process control or monitoring device that takes the necessary countermeasures in the event of a defect.

Furthermore, it can be expedient if the humidity sensor is designed with an integrated response behavior and / or a parameterization, for example for humidity management in the seal back space. The humidity sensor or a sensor structure can permanently measure the humidity level in the seal back space and compare it with specified target values, for example with the target value of the tolerance range within which the humidity sensor does not provide a defect signal.

Incidentally, with regard to Industry 4.0, it is conceivable to compare the measured humidity with other parameters from the system, for example the number of strokes of the process valve, sterilization times and temperatures, etc. in order to achieve increased reliability in monitoring. Overall, a mechanically simple and inexpensive system for monitoring is created for the customer, which ensures high reliability. Dispensing with the use of a possibly critical external medium in the seal back space makes the application safe and does not impair the product and does not endanger employees or maintenance personnel. The customer can attach the system to the process valve with little effort because it is “plug and play”, so to speak. The exact function and parameterization of the humidity sensor can be encrypted on the software side.

In an expedient embodiment, the membrane is arranged in a cartridge inserted from the outside into an outlet of the seal rear chamber, preferably with a larger diameter than that of the outlet in a cartridge housing with outlet openings that is wider than the outlet.

If the check valve is provided, this can be arranged together with the membrane in the cartridge.

Particularly expediently, there is a temperature gradient across the product space with hot product, hot cleaning agent or superheated steam, as used for a product change or for sterilization, between the product space and the seal back space and the environment, which is sufficient for the evaporation of smaller amounts of liquid entered in the seal back space.

• 1 einen Teilaxialschnitt einer Ausführungsform eines Prozessventils,
• 2 einen Teilaxialschnitt einer weiteren Ausführungsform, und
• 3 ein Diagramm zum Verdeutlichen der Arbeitsweise des Prozessventils beziehungsweise einer Vorrichtung als Ausstattung des Prozessventils.

Embodiments of the subject matter of the invention are explained with the aid of a process valve, for example for a food processing or filling system. Show it:

• 1 a partial axial section of an embodiment of a process valve,
• 2 a partial axial section of a further embodiment, and
• 3 a diagram to clarify the operation of the process valve or a device as equipment of the process valve.

1 shows a process valve P, which is used, for example, for process engineering in the processing of liquid food products under preferably aseptic conditions. The processed product may be hot. With regard to aseptic conditions, the inside of the valve is sterilized cyclically with a cleaning medium, which can be hot, or with superheated steam. External cleaning is also required in the area of application of the process valve, or the process valve is operated under wet ambient conditions.

A housing 1 that is open at the top, for example, is covered by a locking ring 2 and a seal 11. The locking ring 2 is connected to a drive 4, for example a pneumatic drive, via a so-called lantern 3. The housing 1 delimits a product space 5 in which, for example, a plate-shaped closure member 6 is actuated by means of a linearly adjustable plunger 7 which is connected to a drive part 9 via a coupling 8.

A ring plate 10 is fixed between the locking ring 2 and the housing 1. The locking ring 2 and the housing 1 are fixed, for example, by a releasable clamping mechanism 22.

In the product space 5, the part of the plunger 7 extending there is hermetically sealed by a bellows seal 12, which is tightly fixed on the ring plate 10 and the closure member 6. In the 1 The bellows seal 12 shown is a primary diaphragm or bellows seal A of the process valve P.

The bellows seal 12, together with the locking ring 2 and the plunger 7, delimits a seal rear space 13 which communicates with the environment and in which a humidity sensor 15 is mounted. As a dynamic seal B of the plunger 7 is in the embodiment in 1 a sliding seal 14 is shown in the locking ring 2 through which the plunger 7 passes.

Instead of at least one sliding seal, at least one bellows or membrane seal (not shown) could also be provided in this area.

An outlet 18 opens out from the seal rear space 13 in the locking ring 2 to the environment. In this outlet 18, a cartridge 17 is fixed, in which a water-vapor-permeable, but water-blocking membrane 16 is installed. The membrane 16 has z. B. has a larger diameter than the outlet 18 and it is tightly fixed in a cartridge housing part that is widened in relation to the outlet 18 and has outlets 20 to the environment in a space 19.

Optionally, a check valve 21 can be provided in the cartridge 17, which opens with a certain spring preload when there is excess pressure in the flow direction to the environment from the cartridge 17, and blocks in the flow direction to the seal back space 13. The check valve 21 is z. B. arranged between the seal back space 13 and the membrane 16.

The embodiment of the process valve P in 2 differs from that of the 1 by another type of membrane or bellows seal A. That is in 2 instead of the bellows 12 of the 1 a liquid-tight, flexible and annular membrane 23 is installed, which is sealed inside between the closure member 6 and a support plate 24 clamped between the plunger 7 and the closure member 6, and has a sealing seat in the large-diameter edge area between the ring plate 10 and the housing 1. The further structure of the process valve P in 2 corresponds to the 1 . The functions of the two embodiments are the same.

As an option, in 2 also indicated that the electronic humidity sensor 15 (connected to a working power supply) can have an integrated temperature sensor 25 in order to compensate for temperature changes more easily and can also be connected to a process control or monitoring device CU.

The humidity sensor 15 can emit a defect signal or a good signal directly (e.g. optically or acoustically) and / or inform the assigned control. The desired response behavior and a parameterization can be integrated into the humidity sensor 15 on the software side. The humidity sensor 15 can be designed in such a way that it permanently measures the humidity level in the seal back space 13 and compares it with predetermined setpoints, whereby it can be operated with a lower response tolerance range within which no defect is reported despite the detected humidity. With regard to Industry 4.0, it is conceivable that the humidity measured by the humidity sensor 15 is compared with other parameters of a process system, such as the number of strokes of the process valve, sterilization times and temperatures, in order to increase reliability when monitoring the process valve P for a defect the membrane or bellows seal A.

The humidity sensor 15 and the membrane 16 are also components of a device V for monitoring the process valve P with regard to defects. The device V can already be incorporated into the process valve P by the manufacturer or it can be retrofitted if necessary.

• Die 3 verdeutlicht diagrammartig eine Arbeitsweise mit dem Prozessventil. Auf der vertikalen Achse 26 des Diagramms ist die Feuchte beispielsweise in Prozent aufgetragen, während die horizontale Achse den Zeitverlauf t repräsentiert. Der Abstand in Prozent Feuchte zwischen der horizontalen Achse 27 und einer dazu z. b. parallelen Linie 28 repräsentiert einen unteren Ansprech-Toleranzbereich des Feuchtesensors, innerhalb dessen dieser kein Defektsignal erzeugt. Eine Kurve 30 repräsentiert den Verlauf der Feuchte in Prozent innerhalb des Dichtungsrückraums 13 über die Zeit. Ansteigende Kurventeile repräsentieren eine Zunahme der Feuchte, wohingegen abfallende Kurventeile Abnahmen der Feuchte zeigen. Eine zur Grundlinie 27 parallele Linie 29 repräsentiert eine reelle Schwankungsbreite der Feuchte (z. B. ein vorab ermittelter Erfahrungswert), bedingt durch einen Wassereintrag entlang des Stößels 7 (Fahrstuhleffekt) und/oder auftretendes Kondenswasser. Die Mengen sind relativ klein und verbleiben innerhalb der reellen Schwankungsbreite 29, weil zyklisch oder permanent vom Produktraum 5 her im Dichtungsrückraum 13 erhöhte Temperatur (Temperaturgefälle ΔT) erzeugt wird, die die vorliegende Wassermenge zumindest zum Teil verdampft und durch Dampfdruck über die wasserdampfpermeable Membran 16 in die Umgebung treibt. Solange also kein Defekt der Membran- oder Balgabdichtung A eintritt, misst zwar der Feuchtesensor die Feuchte, ohne ein Defektsignal zu generieren. Kommt es zu einem Defekt, dann steigt die Kurve 30, wie rechts gezeigt, steil an, bis der Ansprech-Toleranzbereich 28 am Punk 31 überschritten wird, weil die erhöhte Temperatur ΔT im Dichtungsrückraum 13 nicht mehr ausreicht, um die dann aufgrund des Defektes eintretende Flüssigkeits- oder Wassermenge zu verdampfen und durch die begrenzte Kapazität aufweisende Membran 16 auszutreiben. Am Punkt 31 wird dann konsequent eine Bruchdetektion der Membran- oder Balgabdichtung A festgestellt und gemeldet.

With the process valve P can according to 3 can be worked as follows:

• the 3 illustrates a method of working with the process valve in the form of a diagram. The moisture is plotted, for example in percent, on the vertical axis 26 of the diagram, while the horizontal axis represents the time curve t. The distance in percent humidity between the horizontal axis 27 and a line 28 parallel to it, for example, represents a lower response tolerance range of the humidity sensor, within which the latter does not generate a defect signal. A curve 30 represents the course of the moisture in percent within the seal back space 13 over time. Rising parts of the curve represent an increase in moisture, whereas falling parts of the curve show a decrease in moisture. A line 29 parallel to the base line 27 represents a real fluctuation range of the moisture (e.g. a previously determined empirical value), caused by water entry along the tappet 7 (elevator effect) and / or condensation water that occurs. The quantities are relatively small and remain within the real fluctuation range 29, because cyclically or permanently increased temperature (temperature gradient ΔT) is generated cyclically or permanently from the product space 5 in the seal back space 13, which at least partially evaporates the amount of water present and through vapor pressure through the water vapor permeable membrane 16 in the environment drifts. As long as there is no defect in the membrane or bellows seal A, the humidity sensor measures the humidity without generating a defect signal. If a defect occurs, then curve 30 rises steeply, as shown on the right, until the response tolerance range 28 is exceeded at point 31, because the increased temperature ΔT in the seal rear space 13 is no longer sufficient for the temperature that then occurs due to the defect To evaporate the amount of liquid or water and expel it through the limited capacity membrane 16. At point 31, a breakage detection of the diaphragm or bellows seal A is then consistently determined and reported.

In this case, the check valve 21 acts as a flanking effect in such a way that when the volume of the seal back space 13 decreases due to the stroke movement of the closure member 6, air and / or steam is expelled into the environment, whereas when the volume of the seal back space 13 increases, the check valve 21 blocks and a negative pressure situation arises in the seal back space 13, which has the advantage that, in the event of a defect, product or water from the product is sucked into the seal back space 13 and no contaminated water or dirt from the seal back space 13 gets through the defect point into the product space P.

If the check valve 21 is not provided, the membrane 16 may be able to take over the ventilation of the increasing or decreasing seal back space 13, expediently even with a throttling of the sucked in air with enlargement of the seal back space in order to achieve a desired negative pressure situation in this to adjust.

The membrane 16 consists, for example, of PTFE or another water-vapor-permeable, but water-blocking plastic, and can optionally be reinforced or supported by a fabric.

Instead of the 1 and 2 As an alternative, a diaphragm which can be moved by the plunger 7 between the open and closed positions can be provided.

Should the dynamic seal 14 become defective and allow larger amounts of water to pass from the surroundings to the seal back space 13, then this defect is also detected and reported by the humidity sensor 15.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 4688601 A [0003]
• DE 9116465 U1 [0003]
• DE 4419487 B4 [0004]
• EP 2118545 B1 [0004]
• EP 0945658 B1 [0004]
• EP 1726855 B1 [0004]
• EP 1097330 B1 [0004]
• US 794595 B2 [0004]

Claims (13)

Process valve (P), in particular for sterile process engineering in the processing or filling of liquid food products, with a housing (1) having a product space (5) in which the product space (5) is connected to a sealing back space (13) communicating with the environment Membrane or bellows seal (A), (12), (23) is separated in a liquid-tight manner, and with a device (V) for detecting at least one defect in the membrane or bellows seal (A), the device (V) having at least one humidity level The moisture sensor (15) which detects the rear seal space (13), characterized in that a membrane (16) which is permeable to water vapor but is water-blocking is installed between the rear seal chamber (13) and the surroundings. Process valve after Claim 1 , characterized in that a closure member (6) adjustable via a drivable plunger (7) is provided in the product space (5), so that the membrane or bellows seal (A) passes through the plunger (7) through the rear seal space (13) containing this air Seals the product space (5) so that the moisture sensor (15) can be operated with a selected lower response tolerance range (28), and that via the membrane (16) with a defect-free membrane or bellows seal (A) in the seal back space (13) within the response -Tolerance range (28) permanent humidity is adjustable. Process valve according to at least one of the preceding claims, characterized in that the membrane (16) consists of PTFE (e.g. trade name Gore-Tex). Process valve according to at least one of the preceding claims, characterized in that the plunger (7) guided from the housing (1) to a drive (4) is sealed in the housing (1) from the environment by a dynamic seal (B). Process valve after Claim 4 , characterized in that the dynamic seal (B) for the plunger (7) comprises at least one sliding seal (14), a sealing membrane or a bellows. Process valve according to at least one of the preceding claims, characterized in that a check valve (21) blocking in the flow direction into the seal rear chamber (13) is provided between the seal rear space (13) and its surroundings in the direction of flow to the membrane (16) in front of the membrane (16) . Process valve according to at least one of the preceding claims, characterized in that the humidity sensor (15) is equipped with an integrated temperature sensor (25) and, preferably, is linked to a process control or monitoring device (CU). Process valve according to at least one of the preceding claims, characterized in that the humidity sensor (15) is designed with an integrated response behavior and / or parameterization, for example for humidity management in the seal back space (13). Process valve according to at least one of the preceding claims, characterized in that the membrane (16) is arranged in a cartridge (17) inserted from the outside into an outlet (18) of the seal rear chamber (13), preferably with a larger diameter than that of the outlet (18) ) in a cartridge housing widened in relation to the outlet (18) with outlet openings (20). Process valve according to at least one of the preceding claims, characterized in that the check valve (21) is arranged together with the membrane (16) in the cartridge (17). Process valve according to at least one of the preceding claims, characterized in that with hot product, hot cleaning agent or superheated steam in the product space (5) between the product space (5) and the environment in the seal back space (13) there is a permanent or cyclical temperature gradient for at least partial evaporation in the seal back space (13) entrained liquid can be generated. Device for monitoring a seal back space (13) of a defect-prone membrane or bellows seal (A) of a process valve (P) with a humidity sensor (15), the process valve having a housing (1) having a product space (5), the product space (5) of which is separated in a liquid-tight manner from a seal back space (13) communicating with the environment by a membrane or bellows seal (A), characterized in that the seal back space (13) of the membrane or bellows seal (A) by a water vapor permeable but water blocking membrane (16) of is separated from the environment, which, with a defect-free membrane or bellows seal (A), allows quantities of liquid entrained or condensed in the seal back space (13) to be discharged at least to a limited extent by evaporation, but seals the seal back space (13) against liquids from the outside. Food processing or filling plant with a process valve (P), which according to Claim 1 formed or with the device according to Claim 12 Is provided.

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