DE102005024674B4 - Method for checking the tightness of a valve arrangement arranged in a circuit through which a gaseous or liquid medium flows - Google Patents

Abstract

Method for checking the tightness of a valve arrangement (12) arranged in a circuit (10) through which flows a gaseous or liquid medium, the valve arrangement (12) comprising a first and a second valve (14, 16) arranged in series with the first valve, and the first valve (14), viewed in the flow direction (S), is arranged upstream of the second valve (16), characterized in that
that the two valves (14, 16) of the valve arrangement (12) are closed at the same time and the closing time is stored,
in that, after closing the two valves (14, 16) of the valve arrangement (12), the chronological course of the structure-borne sound level value of the first valve (14) is determined via a structure-borne sound sensor arranged on the first valve (14) for determining structure-borne sound level values;
that after the passage of a freely adjustable time interval after the closing time present structure-borne sound level value for signaling
the tightness of the valve assembly (12) is used, wherein a body sound level value of 0 db compared to a plant reference value for a tolerable leakage, the tightness of the ...

Description

The The invention relates to a method for checking the tightness of a in one of a gaseous or liquid Medium flowed through circulation arranged valve arrangement according to the im Preamble of claim 1 specified type, and a valve assembly to carry out the method according to claim 9th

In safety-relevant circuits, such as in the chemical industry or in power plants, is in the interest of keeping air and water clean Tightness of the circuit and in particular the tightness the in-circuit valves are of paramount importance. Around to ensure the tightness of the valves in circulation it is common practice to provide a "valve redundancy" d. H. Two valves are arranged in series, even in case of failure one of the two valves ensure sufficient tightness to be able to. The following is simplified for two valves arranged in series used the term valve arrangement.

From the DE 199 24 377 B4 is a diagnostic system for an actuatable by a positioner via a drive valve with a device for recording, storage and evaluation of structure-borne noise spectra known. For this purpose, the valve is closable for diagnostic purposes and the similarity of the thereby recorded structure-borne sound spectrum with a sound previously recorded intact, at slightly open state of the valve, and stored in the device structure is used as a criterion for a leakage of the valve.

In the DD 232 964 A1 discloses a method and an arrangement for functional testing of safety valves. In this case, the structure-borne noise is absorbed at the valve housing and converted into a proportional electrical signal in the amount of the seat of the safety valve. From this electrical signal, after amplification, the spectral components, which are preferably excited by the flow sound of the medium through the valve, are filtered out and a level is determined. This level is compared with a limit value determined by calibration measurement, which is characteristic of the complete closing, whereby an exceeding of this limit value signals the state "not closed".

When particularly disadvantageous proves in the disclosed methods the fact that these are merely statements about the tightness of a valve, namely of the valve to be checked deliver, d. H. a statement or verification of the tightness of a Valve assembly is not possible with the disclosed methods. moreover is used in both procedures for the implementation a tightness test respectively requires a reference signal to be determined previously on the intact valve.

In the DE 102 47 167 A1 a Dichtprüfeinrichtung and a method for leak testing is disclosed. The Dichtprüfeinrichtung for valves has a valve disposed between the pressure sensor, which is connected to a test unit. This checks the pressure curve in the volume enclosed by the valves after the trial opening and closing of the input-side valve and the output-side valve. It proves to be disadvantageous here that the two valves must be opened one after the other and closed again in order to be able to measure and evaluate the chronological course of the pressure.

Another method for leak detection of two valves arranged in series is from the JP 63-134 931 A known. For leakage determination, the pressure curve between two shut-off valves is also used, whereby the valves are closed in time offset to each other also in this method.

Of the Invention is based on the object, a method for checking the Tightness of one in a gaseous or liquid medium perfused Circuit arranged valve arrangement according to the preamble of the claim 1 specified type such that a simple review of Tightness of a valve arrangement is made possible.

These The object is achieved by the characterizing features of claim 1 solved in conjunction with its generic features.

The under claims form advantageous developments of the invention.

A corresponding valve arrangement for carrying out the method is the subject of claim 9.

Of the The invention is based on the finding that for a qualified statement about the Tightness of a valve assembly a check of the tightness of each, in the valve assembly arranged valves is desirable.

For this purpose, the valve arrangement has a first and a second valve arranged in series with the first valve, the first valve being arranged in the flow direction (S) upstream of the second valve. According to the invention, the two valves are closed at the same time to check the tightness of the valve assembly and the closing time of the two valves is fedi chert. After closing the two valves of the valve arrangement, the structure-borne sound level value of the first valve is determined via a structure-borne sound sensor arranged on the first valve for determining structure-borne sound level values. A structure-borne sound level value present after the passage of a freely adjustable time interval is used for signaling the tightness of the valve arrangement, with a structure-borne noise level value of 0 db signaling the tightness of the valve arrangement.

To the closing the two valves of the valve assembly prevails before the first valve a bigger pressure as in the space formed by the first and second valves. Is now in the valve assembly, for example, the first valve leaking, so flows due to the pressure difference, a short time in the first valve internal, significant leakage current. This leakage current can over the Structure-borne sound sensor arranged on the first valve be measured. For In the case of a dense second valve, this significant leakage current flows until, before and after the first valve, a pressure equalization has set. This means that after a corresponding time interval has elapsed, leaking first valve the significant leakage flow dried up and a body sound level value of 0 db. As a result, a structure-borne sound level value is signaled of 0 db the tightness of the valve assembly.

has but now also the second valve in the valve assembly a leak On, consequently, the leakage current will not dry up, with the result is that after expiration of the corresponding time interval a non-zero structure-borne noise level has set. As a result, one signaled different from zero Body sound value the leakage of the valve assembly.

Understandably In this case, in the above embodiment, the term "tightness of the valve arrangement" does not mean zero leakage. but one of valve size and valve type the two valves more dependent, not stronger resolvable Leakage value of the valve arrangement.

On a simple way is thus provided a method that over a logical link of time and structure-borne noise information as well as optionally stroke information of the two valves a statement about the Tightness of the valve assembly and the cause of a possible Leakage is possible. The fact that in accordance with the method according to the invention proves to be particularly advantageous only at one of the two valves, namely at the first valve, a structure-borne sound sensor necessary to make a statement about to allow the tightness of both valves.

Preferably evaluates the structure-borne sound sensor Determination of structure-borne sound level values a special frequency range. The special frequency range characterized by the fact that this almost unaffected from other disturbances, such as z. B. caused by near installed pumps or other open valves is. The evaluation of the special frequency range has the advantage that thereby the previous determination of a reference value of one or both valves the valve assembly for checking the tightness a valve assembly is no longer necessary.

According to one particularly advantageous embodiment the invention will after closing the two valves of the valve assembly via appropriately arranged Pressure sensors, a first time pressure curve and a second determined temporal pressure curve. This is in the first temporal pressure course around that in the flow direction (S) considered before the first valve over measured pressure for a certain period of time and at the second time Pressure curve around the flow direction (S) looks in front of the second valve, that is in the first of the and the second valve formed gap, over a certain period of time measured pressure.

By the determination according to the invention of first and second pressure curve is in a simple way and Way possible, in addition to a statement about Tightness of the valve assembly also a statement about the Cause of the leak, d. H. in the form of the leaking first valve alone or from both valves. As already stated, prevails after closing the two valves before the first valve, a greater pressure than in the of The intermediate space formed by the first and second valves. We know now For example, only the first valve leaks, so comes after expiration of a time interval due to the flowing leakage current to a pressure equalization, d. h., that after expiration of the time interval the pressure in the gap is up to the level of pressure rises the first valve. As a result, one will signal for one certain time interval observed pressure equalization of the two measured pressure gradients a leaking first valve in the valve assembly.

A statement about the degree of leakage of the first valve is also possible over the time sequence which is to be observed, namely the period of time required for a complete pressure equalization: If the observed pressure equalization has already occurred after a short period of time, this speaks for itself relatively large internal leakage current of the first valve and thus for a greater leakage of the same, while a slow-running pressure equalization signals a correspondingly better valve behavior.

is next to the first valve and the second valve leaking, so finds due to the leakage flow of the second valve no complete pressure equalization instead of. This means that the pressure measured in the gap is indeed however, this pressure increases the pressure level before the first valve not reached. As a result, such a course of the second pressure curve, the leakage of the second valve.

For another Processing is the determined or measured data, such as closing time the valves, stroke information of the valves, time course of the Body noise value the first valve, first and second pressure profile and length of the freely adjustable time interval, a storage and evaluation unit fed. This data could then be from the storage and evaluation in a conventional manner be further processed.

According to one embodiment The invention generates the memory evaluation unit after processing the data an acoustic and / or optical and / or electrical Signal to signal the condition of the checked valve assembly. The output of an optical and / or acoustic and / or electrical Signal proves to be advantageous, since thus a fast and intuitive sensing of the condition of the valve assembly under review is enabled. If the evaluation unit is integrated in the positioner of the valve with structure-borne sound sensor, then can with communication ability of the Positioner also sent an alarm to the process control system become.

Preferably closing takes place the two valves of the valve assembly in an emergency shutdown automatically. The automatic closure the two valves of the valve assembly is particularly for safety-relevant Circuits, for example the chemical industry or similar, significant.

According to one embodiment The invention may be closed the two valves, in particular after a closure of the two valves in an emergency shutdown, the first valve once again briefly opened and subsequently be closed again. The possibility a short-term opening has the advantage that with it an active verification of the tightness of the second Valve allows becomes.

in principle is over the structure-borne sound sensor arranged on the first valve, a continuous measurement of structure-borne noise levels guaranteed. According to one embodiment will the for the determination of the tightness of the valve assembly required body sound level value after closing of the two valves and expiration of a time interval ≥ 20 sec. determined. The value of 20 sec. has proven to be advantageous in test series proved, since this time interval is usually sufficient, to allow pressure equalization when the first valve is leaking. The value of ≥ 20 sec. is here only as an exemplary value of a particular advantageous embodiment and not as a limitation to understand exactly this value. Of course, also embodiments with smaller or larger time intervals conceivable.

The Valve arrangement for implementation of the method comprises a first valve and one in series with the first Valve arranged second valve, wherein the first valve in the flow direction considered upstream is arranged to the second valve and between the two valves a gap is formed; one associated with the first valve Noise sensor, as well as a storage and evaluation unit for storing and evaluating the recorded data, namely the closing date the two valves, the time course of the structure-borne sound level value the first valve, the stroke information of the two valves and the Length of the free adjustable time interval.

According to one particularly advantageous embodiment the valve assembly further comprises one in the flow direction considered before the first valve arranged first pressure sensor for receiving a first pressure profile and one in the intermediate space arranged second pressure sensor for receiving a second pressure profile. The first and second pressure profiles are from the storage and evaluation unit detected and for signaling the tightness of the valve assembly used.

at The first valve may be a control valve with safety function and the second valve is an on / off valve with safety function act. It is also conceivable that it is the first valve around an on / off valve with safety function and accordingly at the second valve is a control valve with safety function.

In a preferred embodiment The invention relates to the structure-borne sound sensor integrated into the first valve. This will be a compact design guaranteed.

Preferably, the control valve with safety function comprises a positioner, a solenoid valve and an actuator. This is the actuator in particular a pneumatic actuator. The abovementioned components of the control valve can expediently be designed at least partially as a structural unit.

According to one another embodiment invention also form the positioner and the memory and evaluation a unit.

The On / off valve with safety function essentially comprises one Actuator and a solenoid valve. These components can at least partly be designed as a unit.

The Use of solenoid valves, eg. B. for venting pneumatic actuators, proves to be safety-relevant circuits due to their robustness, weather resistance, dirt resistance and their high venting performance as especially advantageous.

Around a safe response of the two solenoid valves and thus a safe Shut down to ensure the valves the two solenoid valves are preferably via a safety circuit connected with each other.

Further Advantages, features and applications of the present Invention will become apparent from the following description with the in the drawing illustrated embodiment.

The Invention will now be described with reference to the drawing Embodiment described in more detail.

In the description, in the claims, in the abstract and in the drawing are the ones listed in the list below the reference numbers used terms and associated reference numerals used. In the drawing:

1 a valve assembly for carrying out the method for checking the tightness;

2 a graph showing the course of the structure-borne sound level in the case of a sealed valve assembly, and

3 a graph showing the structure-borne sound level in the event of a leaking valve assembly.

In 1 is more or less schematically a section of a safety-relevant cycle 10 shown. In the cycle 10 is a valve assembly 12 integrated. The valve arrangement 12 includes a first valve 14 and a second valve disposed in series with the first valve 16 , In the flow direction (S), this is the first valve 14 upstream to the second valve 16 arranged. The first valve 14 is in operative connection with a structure-borne sound sensor (not shown here for reasons of clarity). About this structure-borne sound sensor is in a known manner, the determination of structure-borne noise level values of the first valve 14 allows.

in this connection evaluates the evaluation of the signal from the structure-borne sound sensor only one special frequency range, namely a frequency range, which is almost unaffected by other disturbances, such as caused by disturbances near installed pumps, or the like.

At the first valve 14 it is a control valve with a positioner 18 , a first actuator 20 and a first solenoid valve 22 for controlling the actuator 20 , The positioner 18 is over a line 24 with a, not shown here for reasons of clarity, connected process control loop.

The positioner 18 also has a storage and evaluation unit, not shown here for reasons of clarity, via which further processing of various data / measured values is made possible in a manner known per se.

The second valve 16 is as on / off valve with a second actuator 26 and a second solenoid valve 28 for controlling the second actuator 26 educated. The two solenoid valves 22 . 28 stand over a security circuit 30 in operative connection with each other.

In case of an emergency shutdown falls on both valves 14 . 16 the voltage of the solenoid valves 22 . 28 from. As a result, the two actuators 20 . 26 placed in safety position to close the valves and thus the flow through the valves 14 . 16 stopped.

A check of the tightness of the valve assembly 12 is done as follows:
As a result of valve closure of the valve assembly 12 is in a first phase after the emergency shutdown, ie immediately after closing the two valves 14 . 16 the valve assembly 12 , the pressure before the first valve 14 greater than in one, from the first and second valves 14 . 16 formed gap 32 ,

Is now for example the first valve 12 leaking, so for a short time, a significant, internal leakage current flow. With a tight second valve 16 will come after a reasonable waiting time between first valve 14 and the gap 32 to set a pressure balance, ie the significant internal leakage flow within the leaking first valve 14 will dry up. This circumstance, namely the drying up of the internal leakage current in the first valve 14 , causes the structure-borne sound level value to drop continuously to 0 db. In the present case, the structure-borne sound level value required to determine the tightness was determined after a waiting time of 20 seconds. certainly.

These described relationships, namely the course of the structure-borne sound level value and the pressure curve over time is in 2 shown. The reference number 34 corresponds to the course of the structure-borne sound level value, reference numeral 36 the first pressure profile before the first valve 14 and reference number 38 the second pressure profile in the gap 38 ,

In the event that now also the second valve 16 is leaking, the internal leakage current in the first valve 14 do not dry up, with the consequence that the structure-borne sound level value does not drop to 0 db. The after the wait of 20 sec. certain body sound level value is therefore a non-zero value and thus signals that the second valve 16 has a leak.

These relationships are graphically in 3 shown. Correspondingly too 2 describes reference number 34 again the course of the structure-borne sound level value and the reference numbers 36 and 38 the pressure curves before the first valve 14 or in the gap 32 , Out 3 it can be seen that in a first phase after closing the two valves 14 . 16 initially a continuous pressure increase in the gap 32 and a continuous decrease of the structure-borne sound level value 34 can be observed. Due to the leaking second valve 16 However, there is no drying of the internal leakage flow in the first valve 14 so that after the wait of 20 sec. has set a non-zero body sound level value.

By an evaluation of in 1 and 2 illustrated pressure gradients 36 . 38 or the structure-borne noise levels 34 is also a statement about the state of the first valve 14 allows. As already stated, immediately after closing the two valves prevails 14 . 16 before the first valve 14 a greater pressure than in the gap 32 ,

Is now the first valve 14 leaking, this results because of the significant leakage current occurring within the first valve 14 to the pressure equalization already described, ie, that after a certain time interval, the pressure 38 in the gap 32 to the level of pressure 36 has risen.

Is, however, next to the first valve 14 also the second valve 16 leaking, as is due to the now occurring also in the second valve significant leakage current of the second valve 16 no complete pressure equalization takes place, ie that in the interspace 32 measured pressure 38 while rising, this pressure 38 the pressure level 36 before the first valve 14 but not reached.

Consequently, a pressure equalization occurring after the expiration of the selected time interval is shown in FIG 1 a leaking first valve 14 , while an occurring pressure curve according to 2 a leak in both valves 14 . 16 the valve assembly 12 signaled.

In addition, a statement about the degree of leakage of the first valve can be made about the time sequence which is to be observed, namely the time required for complete pressure equalization 14 possible.

The present method also allows active verification of the tightness of the second valve 16 ,

This can be done by, for example, after an emergency shutdown the first valve, z. B. by a non-current switched positioner 18 , something is opened again. Consequently, with a tight second valve 16 no increase in the structure-borne noise level can be ascertained.

All listed data or measurement results, in particular temporal course of the structure-borne sound level value of the first valve, stroke position of the valves, first and second pressure profile and the length of the selected time interval are fed to the already mentioned memory and evaluation, based on the evaluation, ie the Determining a sealed or leaking valve assembly 12 or determination of which of the two valves 14 . 16 is leaking, done.

The result of the evaluation is present as a combined optical / acoustic signal via the positioner 18 output.

The term leaking valve assembly, however, does not refer to the case of "zero leakage", but one of valve size and valve type of the two valves 14 . 16 dependent, not more resolvable leakage value of the valve assembly 12 ,

10

circulation

12

valve assembly

14

first Valve

16

second Valve

18

positioner

20

first actuator

22

first magnetic valve

24

management

26

second actuator

28

second magnetic valve

30

safety circuit

32

gap

34

course the structure-borne sound level value

36

pressure curve in front of the first valve

38

pressure curve gap

S

flow direction

Claims (19)

Method for checking the tightness of a circuit through which a gaseous or liquid medium flows ( 10 ) arranged valve arrangement ( 12 ), wherein the valve arrangement ( 12 ) a first and a second valve arranged in series with the first valve ( 14 . 16 ) and the first valve ( 14 ) in the flow direction (S) upstream of the second valve ( 16 ), characterized in that the two valves ( 14 . 16 ) of the valve assembly ( 12 ) are closed simultaneously and the closing time is stored, that after closing the two valves ( 14 . 16 ) of the valve assembly ( 12 ) via one on the first valve ( 14 ) arranged body sound sensor for the determination of structure-borne sound level values of the temporal course of the structure-borne sound level value of the first valve ( 14 ), it is determined that a structure-borne sound level value present after the expiry of a freely adjustable time interval after the closing time for signaling the tightness of the valve arrangement ( 12 ), wherein a body sound level value of 0 db compared to a plant reference value for a tolerable leakage, the tightness of the valve assembly ( 12 ) and the temporal course of the structure-borne sound level value is a measure of the possible leakage of the first valve ( 14 ). Procedure for checking the Tightness of a valve arrangement according to claim 1, characterized in that that the structure-borne sound sensor for determination of structure-borne noise level values evaluates a specific frequency range that is almost unaffected from usual noise, in particular caused by pumps, and / or others in the Nearby installed, opened Valves, is. Method for checking the tightness of a valve arrangement according to claim 1 or 2, characterized in that after closing the two valves ( 14 . 16 ) via corresponding pressure sensors, a first temporal pressure curve ( 36 ) and a second temporal pressure curve ( 38 ), wherein the first pressure curve ( 36 ) in the flow direction (S) before the first valve ( 14 ) and the second pressure curve ( 38 ) in front of the second valve ( 14 ), ie in the area between the two valves ( 14 . 16 ) of the valve assembly ( 12 ). Method for checking the tightness of a valve arrangement according to one of the preceding claims, characterized in that the determined data, in particular closing time of the two valves ( 14 . 16 ), the time course of the structure-borne sound level value of the first valve ( 14 ), Stroke information of the two valves ( 14 . 16 ), first and second pressure course ( 36 . 38 ), Length of the free adjustable time interval, a storage and evaluation unit to be forwarded. Procedure for checking the Tightness of a valve assembly according to one of the preceding Claims, characterized in that after evaluation of the data from the memory and evaluation an optical and / or acoustic and / or electrical signal is generated. Method for checking the tightness of a valve arrangement according to one of the preceding claims, characterized in that the closing of the two valves ( 14 . 16 ) of the valve assembly ( 12 ) takes place automatically as part of an emergency shutdown. Method for checking the tightness of a valve arrangement according to one of the preceding claims, characterized in that after closing the two valves ( 14 . 16 ) the first valve ( 12 ) is briefly opened again and closed again. Method for checking the tightness of a valve arrangement according to one of the preceding claims, characterized in that the device for signaling the tightness of the valve arrangement ( 12 ) used body sound level value of the first valve ( 14 ) after expiry of a time interval ≥ 20 s. Valve arrangement ( 12 ) for carrying out the method according to one of the preceding claims, comprising - a first valve ( 14 ) and one in series with the first valve ( 14 ) arranged second valve ( 16 ), the first valve ( 14 ) in the flow direction (S) upstream of the second valve ( 16 ) and between the two valves ( 14 . 16 ) a gap ( 32 ) is trained; - one the first valve ( 14 ), and - a storage and evaluation unit for storing and evaluating the closing time of the two valves ( 14 . 16 ), the temporal course of the structure-borne sound level value ( 34 ) of the first valve ( 14 ), the stroke information of the two valves ( 14 . 16 , as well as the length of the free adjustable time interval. Valve arrangement according to claim 9, characterized in that a first pressure sensor for receiving a pressure curve ( 36 ) in the flow direction (s) viewed from the first valve ( 14 ) and a second pressure sensor for recording a second pressure curve ( 38 ) in the space ( 32 ) and both pressure curves ( 36 . 38 ) detected in the storage and evaluation unit and for signaling the tightness of the valve assembly ( 12 ) be used. Valve arrangement according to one of claims 9 or 10, characterized in that the first valve ( 14 ) and the structure-borne sound sensor form a structural unit. Valve arrangement according to one of claims 9, 10 or 11, characterized in that it is in the first valve ( 14 ) by a control valve with safety function or an on / off valve with safety function and by the second valve ( 16 ) is an on / off valve with safety function or a control valve with safety function. Valve arrangement according to claim 12, characterized in that the control valve with safety function a positioner ( 18 ), a first solenoid valve ( 22 ) and a first actuator ( 20 ). Valve arrangement according to claim 13, characterized in that the positioner ( 18 ) and the storage and evaluation unit form a structural unit. Valve arrangement according to claim 13 or 14, characterized in that the positioner ( 18 ) is capable of communication and can report the tightness condition. Valve arrangement according to claim 12, characterized in that the on / off valve with safety function a second actuator ( 26 ) and a second solenoid valve ( 28 ). Valve arrangement according to claim 13, characterized in that the control valve and / or the positioner ( 18 ) and / or the first solenoid valve ( 22 ) and / or the first actuator ( 20 ) form a structural unit. Valve arrangement according to claim 16, characterized in that the open / close valve and / or the second actuator ( 26 ) and / or the second solenoid valve ( 28 ) form a structural unit. Valve arrangement according to claim 13 and 16, characterized in that the two solenoid valves ( 22 . 28 ) via a security circuit ( 30 ) are interconnected.