DE102015120090A1 - Method for checking a measuring point at which a flow of a fluid is determined - Google Patents

Abstract

A method for checking a measuring point (3) arranged on a pipeline (20), at which a flow of a fluid is determined, by means of a device (2) for checking the measuring point (3), wherein the measuring point (3) at least one flowmeter to be checked (7), a pressure transmitter (9) and a temperature sensor (10); and wherein the device (2) for checking the measuring point (3) has at least one comparison measuring arrangement (4) and one piston testing device (6), wherein the comparison measuring arrangement (4) comprises at least one comparison flow measuring device (16), one pressure transmitter ( 14) and a temperature sensor (15); the method being characterized at least by the following steps: I. checking the comparison flow meter (16) by comparing a comparison flow measurement value determined by the comparison flow meter (16) with measurements of the piston test device (6); II. Checking the flowmeter to be checked (7) by matching at least one DUT measured by the flowmeter to be tested with measured values of the piston testing device (6) and / or with the comparison flow measured value of the previously tested comparison flowmeter (16) and III. Comparison of one or more values representing the measuring point (3) into which or which of the test flow rates of the flowmeter (7) and measured values of the pressure transmitter (9) and of the temperature sensor (10) are received, with one or more of the comparison measuring arrangement (4 ), in which or which the comparative flow measurement values of the comparison flowmeter (16) and measured values of the pressure transmitter (14) and of the temperature sensor (15) are received.

Description

The present invention relates to a method for checking a measuring point, at which a flow of a fluid is determined.

It is known to check flowmeters under conditions of use by means of a piston tester, a so-called provers, so as to check them to see if they give the exact reading under conditions of use.

In many cases, however, a user of the flowmeter with respect to a customer specifies a volume flow which is normalized to 15 ° C. and normal pressure. This value is the basis for billing the amount of fluid delivered to the customer, e.g. In the form of petroleum or other products.

So far, only an on-site individual test of the flowmeter was done.

Based on the above facts, it is now an object of the present invention to provide a method which allows a more comprehensive test under conditions of use.

The present invention solves this problem by a method having the features of claim 1.

An inventive method for checking a measuring point at which a flow of a fluid is determined by means of a device for checking the measuring point; wherein the measuring point has at least one flow meter to be checked, a pressure gauge and a temperature measuring device. These three measuring elements make it possible to measure the flow of the fluid under conditions of use and to convert this flow into a so-called "flow 15 ", Ie a flow at a fluid temperature of 15 ° C and at atmospheric pressure. Usually, it is billed in a volume flow, but the correspondingly standardized flow can also be a mass flow.

The device for checking the measuring point has at least one comparison measuring arrangement and a piston testing device, the so-called prover.

The comparison measuring arrangement has at least one comparison flow meter, a pressure gauge and a temperature measuring device.

• I. Überprüfen des Vergleichs-Durchflussmessgerätes durch einen Abgleich eines vom Vergleichs-Durchflussmessgerät ermittelten Durchflusses in Form eines Durchflussmesswerts oder mehrerer Durchflussmesswerte die vorliegend auch als Vergleichsdurchflussmesswert bzw Vergleichsdurchflussmesswerte bezeichnet werden, mit Messwerten der Kolbenprüfvorrichtung;
• II. Überprüfen des zu überprüfenden Durchflussmessgerätes durch einen Abgleich eines vom zu überprüfenden Durchflussmessgerätes ermittelten Durchflusses, in Form eines Durchflussmesswerts oder mehrerer Durchflussmesswerte, der oder die vorliegend auch als Prüflingsdurchmesswert bzw. Prüflingsmesswerte bezeichnet werden, mit Messwerten der Kolbenprüfvorrichtung und/oder mit dem Durchfluss bzw. dem oder den Vergleichsdurchflussmesswert bzw. Vergleichsdurchflusswerten des zuvor überprüften Vergleichs-Durchflussmessgerätes und
• III. Vergleich eines oder mehrerer die Messstelle repräsentierenden Wertes bzw. Werten, in welchen oder welche der Prüflingsmesswert bzw. die Prüflingsmesswerte des zu überprüfenden Durchflussmessgeräts sowie Messwerte des Drucktransmitters und des Temperatursensors der Messstelle eingehen, mit einem oder mehreren die Vergleichs-Messanordnung repräsentierenden Wert oder Werte, in welchen oder welche der Prüflingsmesswert bzw. die Prüflingsmesswerte des Vergleichs-Durchflussmessgeräts sowie die Messwerte des Drucktransmitters und des Temperatursensors der Vergleichsmessanordnung eingehen.

The method according to the invention is characterized at least by the following steps:

• I. checking the comparison flowmeter by comparing a flow determined by the comparison flowmeter in the form of a flow measurement value or a plurality of flow measurement values which are also referred to herein as comparison flow measurement values or comparison flow measurement values, with measured values of the piston testing device;
• II. Checking the flowmeter to be checked by comparing a flow rate determined by the flowmeter to be checked, in the form of a flow measurement value or a plurality of flow measurement values which are also referred to herein as sample sample value or test sample measurement value, with measured values of the piston tester and / or with the flow rate or the comparison flow measured value or comparison flow values of the previously tested comparison flow measuring device and
• III. Comparison of one or more values or values representing the measuring point, into which or which of the test object measured values or the test object measured values of the flowmeter to be checked and measured values of the pressure transmitter and the temperature sensor of the measuring point are received, with one or more values or values representing the comparison measuring device, in which or which of the test object measured value or the test object measured values of the comparison flow measuring device as well as the measured values of the pressure transmitter and the temperature sensor of the comparison measuring arrangement are received.

The checking in the sense of the present invention is preferably to be equated with the English term "proving" and describes the registration of the deviation of two elements, ie in the present case, the deviation between the flowmeter to be checked and the comparison flowmeter. In contrast, calibration means that in addition to the above-mentioned registration of the deviation also an adjustment takes place.

Measured values in the present case are also readback values which can be traced back to measured values. A measured value can thus be a frequency or the flow itself in the flow measurement. In the case of a Coriolis flowmeter, the measured value of the actual density of the fluid under conditions of use is also a measured value in the sense of the method according to the invention. Thus, it is also possible to convert from a mass flow to a volumetric flow.

Thus, both a check of the flowmeter at the measuring point as well as in the last step, the review of the totality of the three sensor elements, ie the flow meter, the temperature sensor and the pressure transmitter at the measuring point. The user thus receives the statement that not only does his flowmeter measure correctly, but also that the conversion into the volume flow to be invoiced is carried out correctly.

If this check fails, the user knows that a mostly complex individual test of the respective sensors at the measuring point is necessary.

Further advantageous embodiments of the invention are the subject of the dependent claims.

It is advantageous if a bypass pipeline, which is detachably connected to the pipeline, is used to check the measuring point.

The device can advantageously have a density measuring device for checking the measuring point, which determines the density of the fluid under conditions of use. When using a Coriolis flowmeter or another mass flowmeter, the conversion of the mass flow rate to volume flow or the conversion of the volumetric flow rate of the piston testing device to mass flow rate can therefore be carried out.

The piston testing device and the comparison measuring arrangement can advantageously be arranged in series with the measuring point and in the flow direction downstream of this measuring point, preferably in such a way that the fluid in the flow direction is first passed through the measuring point to be checked, then through the piston testing device and finally through the comparison measuring arrangement , The value representing the measuring point and the comparison measuring arrangement is preferably in each case the value determined at the measuring point and at the comparison measuring arrangement corresponds to a volume flow at 15 ° C and at normal pressure or alternatively a mass flow. One of these two values is usually billed directly to customers. Thus, the check is made for the final value and not just for a flow under conditions of use. An incorrect measurement of the temperature sensor, the pressure transmitter or an error in the conversion of the measured values is thus checked and excluded.

The flow meter to be checked may advantageously be a mass flow meter, and the comparison flow meter may use a Coriolis flow meter.

The step of checking the flowmeter to be checked by adjusting a flow determined by the flowmeter to be tested with measured values of the piston testing device can preferably take place before the step of checking the comparison flowmeter by balancing a flow determined by the comparison flowmeter with measured values of the piston testing device.

The step of checking the flowmeter to be checked may include adjusting the flowmeter to be checked based on the measured values of the piston testing device or on the flow of the comparison flowmeter. The flowmeter can thus either be set to the conditions of use or merely checked to see if it still measures correctly under the conditions of use. For both cases, the use of the device according to the method of the invention is possible.

The step of checking the comparison flowmeter may also advantageously include adjusting the comparison flowmeter based on the readings of the piston testing apparatus.

The fluid is preferably a hydrocarbon. More preferably, the fluid may be a liquid, e.g. As a starting material or a product from a refinery and / or still.

The method is preferably for applications according to the recommendation OIML (Organization Internationale de Métrologie) according to R117-1, according to the current version z. Z. the first application.

The checking of the comparison flow meter and / or the meter to be tested can advantageously be checked according to the specifications of the API on the basis of at least 5 cycles of the piston tester, with one check cycle corresponding to a full piston stroke of the piston tester.

The comparison of one or more values representing the measuring point can take place with one or more values representing the comparison measuring arrangement, the output of a calibration factor under conditions of use for the measuring point. Of course, this also includes a traceable to the calibration factor Value. At least the pressure, the temperature and the flow of the fluid or the flowable medium at the measuring point are taken into account in this representative value.

The representative values of the measuring point are preferably exclusively the flow rate determined at the measuring point, the pressure determined at the measuring point and the temperature determined at the measuring point. As a result, the thermal expansion coefficient and the compressibility of the medium or of the fluid are taken into account if a so-called reference density for the medium or fluid is specified. In the case of a mass flow, the density determined at the measuring point can optionally also enter into the representative value (s), in particular in a comparison on the basis of the volume flow, if a reference density is unknown, for example, and must be determined. In the case of a Coriolis flowmeter, this actual density can be determined directly by the flowmeter itself or an additional density meter can be provided. By measuring the current density, the current temperature and the pressure, a corresponding reference density can be determined iteratively.

The method according to the invention will be explained in more detail below on the basis of an exemplary embodiment with the aid of the enclosed figures. Show it:

1 schematically illustrated construction of a system with a device for carrying out the method according to the invention; and

2 Signal sequence during the flow measurement of a flow meter during a check cycle or a piston stroke of a piston tester.

1 shows an arrangement 1 with a measuring point 3 , which on a fluid line 20 , z. A pipeline, and a device 2 to check this measuring point. The fluid may particularly preferably be a liquid, for example a hydrocarbon compound. Liquefied gas, such as propane or butane, is also defined as a liquid in the context of the present invention.

The device 2 and a method operable by the device offers a novel possibility for checking the measuring point 3 at which a flow is determined. It may be in the device 2 preferably a calibration device.

The measuring point 3 includes a pipeline 20 on which a pressure transmitter 9 , a temperature sensor 10 and a flow meter 7 , preferably a Coriolis flowmeter, is arranged.

The flowmeter 7 is with an advertising and / or evaluation unit 8th connected. Normally, only the flowmeter is checked during a check, but not the other sensors of the measuring point 3 So the temperature sensor 10 and the pressure transmitter 9 , Likewise, usually not the display and / or evaluation unit 8th calibrated.

The device 2 is designed as a calibration bypass and can be connected to the fluid line 20 connected. Usual connection points, z. B. flanges, are in 1 not shown. After connecting the calibration bypass, a check valve can be used 11 , which is arranged on the fluid line to be closed, so that a fluid bypass through a conduit system of the device 2 he follows. This line system includes an inlet valve in the area of the connection points 13 and an exhaust valve 12 , which are open in calibration mode.

In the direction of flow A from the inlet 12 to the outlet valve 13 hin is the device points 2 a piston testing device 6 , the so-called Prover, a density meter 5 and a comparative measuring arrangement 4 on.

The comparison measuring arrangement 4 includes a pressure transmitter 14 , a temperature transmitter 15 and a flow meter 16 For example, a Coriolis flowmeter. These are with an evaluation unit 17 connected, which of the device 2 assigned.

The density measuring device 5 is used for on-line density measurement, so the continuous density determination of a current density value of the fluid, which through the device 2 , in particular flows through the Prover. The density measuring device 5 can be designed as a bypass and a shut-off valve 18 be switched. The density measuring device 5 For example, with a Coriolis flowmeter 19 be provided for density determination.

However, it can also be another meter, such. As a Coriolis density meter based on MEMS, are used at this point.

The following is the operation of the device 2 explained in more detail. The goal of the device 2 is a verification of a measuring point, at which a flow is determined, using a Provers, so a highly accurate volumetric measuring instrument.

However, some preliminary considerations are indispensable. In the past, various organizations, such as For example, the API (American Petroleum Institute) investigated the possibility of testing a flowmeter under working conditions using a small volume piston tester. A corresponding Prover will be in the EP 2 665 996 A1 described. The flow meters usually give as the output value to a pulse rate, which corresponds to the current flow rate. However, the signal processing for outputting the pulse rate requires a certain amount of time, depending on the computing power of a processor assigned to the flowmeter. In the case of a flow rate change, this is therefore always displayed after a small time interval by a corresponding evaluation unit of the flow meter. Although this signal conversion often takes only a few hundred milliseconds, it will still affect the Prover check.

Depending on the geometric configuration of the Provers, the Kolbenhubfrequenz may take less than a second, especially in small-volume versions of a Provers. If the plunger of the Provers works, it opens and closes a valve. When the piston stops, the valve remains open and the fluid flows through. When the valve opens or closes due to the piston stroke, a pressure pulse builds up, which reduces the flow somewhat due to the additional flow obstruction. In addition, the flow profile changes. Opposing effects can be observed when the valve closes. A prover can advantageously use two time measuring units T1 and T2 for measuring time intervals for measuring time intervals, which are preferably triggered as time measuring units whose start and stop are triggered by an event, that is to say a very precise stopwatch in the range of microseconds or MHz.

are formed. If the piston moves, so the first time measuring unit T1 by a first sensor, for. As an optical sensor triggered. Furthermore, the first time measuring unit T1 is connected to the second time measuring unit T2. However, this second time measuring unit T2 is not put into operation until a first rising edge of a first pulse of the flowmeter to be checked is reached. As soon as the second time measuring unit T2 is activated, a counter starts, which records the pulses of the flowmeter. Shortly before the end of a piston stroke of the Provers, a second sensor is activated, which stops the time measuring unit T1. By this procedure, the movement time of the piston can be determined in microseconds with known piston volume of a piston stroke.

At the time when the time measuring unit T1 stops, the connection to the time measuring unit T2 is disconnected. However, the time measuring unit T2 continues recording until reaching the first edge of the first pulse of the flowmeter after the time measuring unit T1 has been stopped. At this time, at which the time measuring unit T2 stops, there is also a stop of the counter. Thereby, the number of pulses of the flowmeter is determined and the elapsed time in microseconds during the determination of the number of the aforementioned pulses.

The number of pulses of the flowmeter can be understood as an integer portion of a correction factor K such. In 2 where the term (T1 / T1 * sample volume) is represented as the floating point decimal portion of the correction factor K.

Therefore, to check a flow meter, preferably a Coriolis flow meter, a large amount of measuring points or pulses must be collected.

If the method described above, also called a double-chronometry method, is not used and instead only the number of pulses registered between the contacts of the two aforementioned sensors is registered, significant underscores can occur. Out 2 it can be seen that a plunger which activates or triggers the sensors does not run at the same time as the incoming pulses of the flowmeter. Therefore, one might assume that one can omit the first and the last pulse of the flowmeter. If the repeatability requirements are set to 0.02%, this would not allow uncertainty for more than two pulses of 10,000 pulses. As described above, the double chronometry allows the solution of this problem.

However, the clock rate when acquiring the measuring points should remain constant for reasons of repeatability.

In cases in which z. For example, if an ultrasonic flowmeter is being tested or calibrated as a meter under test, some facts must be considered. The piston strokes may be relatively short and, in practice, less than a second at high flow rates.

In this case, the ultrasonic flowmeter emits an electronically generated pulse based on a measured flow rate and flow profile. The actuation of the piston will close the valve of the piston and a pressure peak will be formed by a pressure pulse. Whereby the flow rate drops slightly is due to the additional pressure difference across the piston. The flowmeter must adjust a new flow rate and flow profile change, taking into account, if applicable, the weighting factors of the sonic flow paths of the ultrasonic flowmeter. As is known, an ultrasonic flowmeter is more sensitive to the change in the flow profile than a positive displacement meter.

The piston will convert the formed flow profile into a more disturbed flow profile, in particular flatten. Even if the ultrasonic flowmeter is fast enough to adapt to the new airfoil before the piston activates or deactivates the first sensor, the sensed result is affected by the changed airfoil during the piston stroke. In these cases, it is recommended to calibrate a flowmeter that is less sensitive or not at all sensitive to flow profile changes to the piston tester, and to use this flowmeter as a comparative flowmeter relative to the ultrasonic flowmeter to be tested.

It is understood that the device 2 not permanently for checking in the area of the measuring point 3 is connected, but can be used for a variety of other measuring points. Therefore, the device 2 preferably designed transportable and can be transported for example in a container from plant to plant. Accordingly, the additional flow meter may be a "master flow meter", which is preferably calibrated or calibrated at certain intervals, in particular at the factory. This flow meter is therefore referred to in the following application as a comparison flow meter. The comparative flow meter is preferably less sensitive and speaks faster to changes, such. Flow profile changes, pressure changes, etc., during the verification pass.

The comparison flowmeter and the Prover are fluidically arranged in series with the flowmeter of the measuring point. The comparison flowmeter is calibrated to a constant flow rate. Alternatively or additionally, the respective K correction factors can be determined and interpolated at different flow rates. It may preferably be calibrated on-site under conditions of use.

The calibration according to the OIML R117-1 depends on the defined classes. So z. For example, the class with the highest requirements of the OIML R117-1 class 0.3. This means that 0.3% is the maximum allowable error of the measurement setup, with the maximum allowable error of the flowmeter being less than 0.2%. Repeatability should be two-fifths of class 0.3 with a maximum allowable error of less than or equal to 0.12% for three consecutive passes. (2/5 of 0.3%). In the specification of the API MPMS 4.8 chapter 4.8, the detail requirements for the statistical evaluation of the required measuring runs are explained in more detail in order to achieve an uncertainty for five consecutive measuring passes, which according to the API specification is 0.05%. While the API specification refers to the repeatability of the measurement, the OIML specification defines a maximum allowable error for the single measurement.

The comparison flowmeter can then be used to compensate for the negative influences on the measurement during the check (pressure fluctuations, flow profile change, ...) by the Prover and the very short-term verification cycles, since the comparison flow meter through longer inspection cycles with constant review criteria Interpolation can generate.

The above aspects explain why a comparative flow meter in the device 2 is used. This comparison flowmeter is the same as the flowmeter 16 the comparative measuring arrangement 4 in the device 2 for carrying out the method according to the invention.

When testing individual flowmeters, as described above, the volume of a sample is compared with the measurement data determined by the flowmeter to be tested. It should effects, such. As the thermal expansion and the compressibility of the fluid, which serves as the measuring medium, are taken into account and compensated, since the temperatures and pressures of the fluid within the Provers can differ from those of the fluid in the flowmeter to be tested. For example, the Prover may be exposed to sunshine while the flowmeter is in the shade. The example shows that the thermal expansion and the elasticity of the sample or of the sample material also have to be taken into account and compensated, since the sample volume also changes as the temperature changes. Often the Prover is made of SS steel.

For the verification of mass flowmeters, such. B. from Coriolis flowmeters must also be determined and taken into account the density of the fluid under conditions of use. For this is in the present contraption 2 a density meter 5 intended. This allows the measured mass flow rate of the mass flowmeter to be compared to a mass flow rate determined from the volume flow rate of the sampler and the density under use conditions.

The following relationships can be used when checking the flowmeter, in this case a Coriolis flowmeter:
For comparison Coriolis - mass flow with Prover volume MFm = (Prover Volume × CTSp × CPSp × ρfp) / IMm (1) ρfp = (ρst × CTLp × CPLp) (2) in which

CTSp

= Korrekturfaktor der thermischen Expansion des Provermaterials;

CPSp

= Korrekturfaktor des Druckeffekts auf das Provermaterial;

ρfp

= Fluid-Dichte unter Anwendungsbedingungen;

IMm

= Angezeigter Massedurchfluss am Coriolis-Durchflussmessgerät;

ρst

= Fluid-Dichte bei 15°C;

CTLp

= Korrekturfaktor der thermischen Expansion des Fluids am Prover;

CPLp

= Korrekturfaktor des Druckeffekts des Fluids auf den Prover;

MFm = device factor if the Coriolis flowmeter is configured in mass flow meter (meter factor mass);

CTSP

= Correction factor of the thermal expansion of the sample material;

CPSP

= Correction factor of the pressure effect on the sample material;

ρfp

= Fluid density under application conditions;

iMM

= Mass flow indicated on the Coriolis flowmeter;

ρst

= Fluid density at 15 ° C;

CTLp

= Correction factor of the thermal expansion of the fluid at the Prover;

CPLP

= Correction factor of the pressure effect of the fluid on the prover;

MFv

= Gerätefaktor, wenn das Coriolis-Durchflussmessgerät in Volumendurchflussanzeige konfiguriert ist;

IMv

= Angezeigter Volumendurchfluss am Coriolis-Durchflussmessgerät;

ρst

= Fluid-Dichte bei 15°C;

CTLm

= Korrekturfaktor der thermischen Expansion des Fluids am Coriolis-Durchflussmessgerät;

CPLm

= Korrekturfaktor des Druckeffekts des Fluids auf das Coriolis-Durchflussmessgerät.

To compare the Coriolis volume flow with the Prover volume: MFv = ((Prover volume × CTSp × CPSp) / IVm) × ((CTLp × CPLp) / (CTLm × CPLm)) (3) in which

MFv

= Device factor, if the Coriolis flowmeter is configured in volume flow display;

IMV

= Displayed volume flow on the Coriolis flowmeter;

ρst

= Fluid density at 15 ° C;

CTLm

= Correction coefficient of the thermal expansion of the fluid at the Coriolis flowmeter;

CPLm

= Correction factor of the pressure effect of the fluid on the Coriolis flowmeter.

The device factor, or correction factor, is the factor which corrects the measuring device in the field. As can be seen from the above formulas, the device factor is still determined by the principle: test measurement data / (number of pulses of the measuring device / K-factor). The K-factor is the divisor or the calibration constant, which assigns the number of generated pulses to the engineering units z. Liter / kg.

The correction factors of individual effects z. As the thermal expansion or the pressure effect, etc. are not equated with the correction factor.

Through a continuous temperature and pressure measurement in the area of the Provers and in the area of the Coriolis flowmeter, changed environmental conditions can be taken into account and compensated directly during the inspection. Although the mass flow measurement is not affected by the aforementioned effects, most fluids in a pipeline or plant, such. As hydrocarbons, in volume (normalized to 15 ° C and under atmospheric pressure) cost accounting at the customer. Therefore, the mass flow rate is often converted into a volume flow rate in the flowmeter or in an evaluation and display unit paged out of the flowmeter.

In a variety of applications has a measuring point 3 not just a flow meter 7 but also via a temperature sensor 10 and a pressure transmitter 9 , Even if only the flowmeter 7 is provided, as described above, optionally a remote display and / or evaluation unit 8th be provided in the event that the flowmeter 7 is installed in a hard to reach place. This is in 1 shown. Also, it may be in the transmission to the evaluation and / or display unit 8th come to a display of erroneous measurement data.

The method according to the invention not only makes it possible to check a single flowmeter 7 Instead, the inspection extends the entire measuring point, including other sensors for temperature measurement, pressure measurement, to an optional display and evaluation unit and to the conversion of mass flow to volume flow.

The process according to the invention can be carried out in several different variants:
In a first step 1 the inventive method according to the first variant of the method can be checked flow meter 7 each with the volume values of the Provers 6 be compared.

This step has already been described in detail in the previews. However, this only becomes an integrity check of the flowmeter 7 and a check of the accuracy of the flowmeter 7 carried out.

Subsequently, the comparison flow meter 16 each with the volume values of the Provers 6 be compared. In this second step II, the comparison flow meter 16 through the Prover 6 calibrated, preferably 5 times, calibrated to ensure a particularly low measurement uncertainty.

The comparison flowmeter 16 Thus, by taking into account the temperature of the medium and the current pressure of the fluid between mass and volume flow.

Finally, in a step III, a comparison is made between the comparison measuring arrangement 4 and the measuring point to be checked 3 ,

In the case that it is in the comparison flow meter 16 and the flowmeter to be checked 7 is about two mass flow meters, such. As to Coriolisdurchflußmessgeräte, the comparison of the two measuring points can be made such that in each case the two calculated volume flow rates are compared. These may particularly preferably be the so-called "volume flow rates 15 ", So in each case the calculated volume flow at the comparison measuring arrangement 4 and the measuring point 3 at 15 ° C and atmospheric pressure. This volume flow corresponds to the values which are the basis for the calculation of the cost of the fluid delivery.

In the case of the comparison flowmeter and the flowmeter to be checked 7 volumetric flow meters, the "volume flow rates 15 "Calculated directly from the measured volume flow rates under application conditions, the respectively determined temperature and the respectively determined pressure at the measuring point or the comparison measuring arrangement.

Since the temperature, the pressure and the conversion as such are taken into account for calculating these volume flows, an overall check can be carried out in this way.

This procedure has proven to be favorable for carrying out a comprehensive check of the measuring point to be checked. If the two flow values deviate significantly from each other, the user knows that a mostly complex individual check of the temperature sensor, the pressure sensor and / or the evaluation unit must be carried out at the measuring point to be checked. However, in the majority of applications these individual checks are not necessarily necessary.

In an alternative second embodiment variant of the method, first of all the comparison flow meter can be adjusted with the prover.

Then, the adjustment of the flowmeter to be checked with the comparison flow meter takes place.

Finally, the comparison measuring arrangement and the measuring point to be checked are compared with one another analogously to the first exemplary embodiment.

LIST OF REFERENCE NUMBERS

1

arrangement

2

Device for checking a measuring point

3

to be checked measuring point

4

Comparison measurement arrangement

5

Density measurement device

6

Kolbenhubvorrichtung

7

to be checked flowmeter

8th

Display and / or evaluation unit

9

pressure transmitters

10

temperature Senor

11

check valve

12

intake valve

13

outlet valve

14

pressure transmitters

15

temperature sensor

16

Comparison flowmeter

17

Display and / or evaluation unit

18

shut-off valve

19

Coriolis flow meter

20

pipeline

A

Flow direction ("A" is a ref. Sign in the figure and not a word)

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• EP 2665996 A1 [0041]

Claims (15)

Procedure for checking a pipeline ( 20 ) arranged measuring point ( 3 ), at which a flow of a fluid is determined, by means of a device ( 2 ) for checking the measuring point ( 3 ) where the measuring point ( 3 ) at least one flowmeter to be checked ( 7 ), a pressure transmitter ( 9 ) and a temperature sensor ( 10 ) having; and wherein the device ( 2 ) for checking the measuring point ( 3 ) at least one comparison measuring arrangement ( 4 ) and a piston testing device ( 6 ), wherein the comparison measuring arrangement ( 4 ) at least one comparison flow meter ( 16 ), a pressure transmitter ( 14 ) and a temperature sensor ( 15 ) having; the method being characterized at least by the following steps: I. checking the comparative flow meter ( 16 ) by comparing one of the comparison flow meter ( 16 ) with the measured values of the piston testing device ( 6 ); II. Checking the flowmeter to be checked ( 7 ) by matching at least one of the flow meter to be checked ( 7 ) measured sample flow value with measured values of the piston testing device ( 6 ) and / or with the comparison flow measured value of the previously checked comparison flow measuring device ( 16 ) and III. Comparison of one or more measuring points ( 3 ), in which or which of the test flow rates of the flowmeter (or 7 ) and measured values of the pressure transmitter ( 9 ) and the temperature sensor ( 10 ), with one or more of the comparison measuring arrangement ( 4 ), in which one or more of the comparative flow measurements of the comparison flow meter ( 16 ) and measured values of the pressure transmitter ( 14 ) and the temperature sensor ( 15 ). Method according to claim 1, characterized in that the device ( 2 ) for checking the measuring point ( 3 ) has a bypass pipe which is detachably connected to the pipeline ( 20 ) connected is. Method according to claim 1, characterized in that the device ( 2 ) for checking the measuring point ( 3 ) a density measuring device ( 5 ) which determines the density of the fluid under use conditions. Method according to claim 1 or 2, characterized in that the piston testing device ( 6 ) and the comparison measuring arrangement ( 4 ) fluidically in series with the measuring point ( 3 ) and in the flow direction (A) according to this measuring point ( 3 ) are arranged, preferably in such a way that the fluid in the flow direction (A) first by the measuring point to be checked ( 3 ), then through the piston testing device ( 6 ) and finally by the comparison measuring arrangement ( 4 ). Method according to one of the preceding claims, characterized in that the measuring point ( 3 ) and the comparison measuring arrangement ( 4 ) representing each of the at the measuring point ( 3 ) and at the comparison measuring arrangement ( 4 ) value corresponding to a volume flow at 15 ° C and at atmospheric pressure and / or a mass flow. Method according to one of the preceding claims, characterized in that it is in the flowmeter to be checked ( 7 ) is a Coriolis flow meter which determines a flow rate and a density, and that as a comparison flow meter ( 16 ) a Coriolis flowmeter is used. Method according to claim 6, characterized in that the flow rate and the density in which the measuring point ( 3 ) and / or into which the measuring point ( 3 ). Method according to one of the preceding claims, characterized in that the step of checking the flowmeter to be checked ( 7 ) by comparing one of the flow meter to be checked ( 7 ) with measured values of the piston testing device ( 6 ) and prior to the step of checking the comparative flow meter ( 16 ) by comparing one of the comparison flow meter ( 16 ) with measured values of the piston testing device ( 6 ) he follows. Method according to one of the preceding claims, characterized in that the step of checking the flowmeter to be checked ( 7 ) a calibration of the flowmeter to be checked ( 7 ) based on the measured values of the piston testing device ( 6 ) or based on the determined flow rate of the comparison flow meter ( 16 ). Method according to one of the preceding claims, characterized in that the step of checking the comparison flow meter, an adaptation of the comparison flow meter ( 16 ) based on the measured values of the piston testing device ( 6 ). Method according to one of the preceding claims, characterized in that it is the fluid is a hydrocarbon. Method according to one of the preceding claims, characterized in that the method according to one of the preceding claims for applications according to the recommendation OIML R117-1 or the recommendation of the API MPMS 4.8 table A.1, according to the current version z. Z. the first application, with at least three repetition runs is performed. Method according to one of the preceding claims, characterized in that the checking of the comparison flow meter ( 16 ) and / or the measuring device to be checked ( 7 ) based on at least five cycles of verification of the piston testing device ( 6 ), wherein one inspection cycle corresponds to a complete piston stroke of the piston testing device ( 6 ) corresponds. Method according to one of the preceding claims, characterized in that the comparison of one or more of the measuring point ( 6 ) with one or more of the comparison measuring arrangement ( 4 ) the output of a calibration factor under conditions of use for the measuring point ( 3 ). Method according to one of the preceding claims, wherein in the representing values or values, only the flow determined at the measuring point, the pressure determined at the measuring point and the temperature determined at the measuring point and, optionally, the density determined at the measuring point, of the fluid.

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