DE102005003631A1 - Turbulence flow measuring method, involves detecting frequency signals of swirled fluid, evaluating and displaying frequency signals, and detecting amplitude signals between swirling of fluid and evaluation of frequency signals - Google Patents

Abstract

The method involves swirling a fluid (2) by a sturgeon body (3), and detecting frequency signals (f) of the swirled fluid. The frequency signals are evaluated and displayed. Amplitude signals (A) are detected between the swirling of the fluid and evaluation of the frequency signals. The amplitude and frequency signals are parallely measured to detect the entire signal of the swirled fluid. An independent claim is also included for a turbulence flow meter for execution of a method of measuring turbulence flow.

Description

The The present invention relates to a method for reliable vortex flow measurement comprising the steps of introducing and passing a fluid through a Vortex flowmeter, vortexing the fluid by means of at least of a sturgeon, capture a frequency signal of the fluid swirling and evaluating and Outputting the detected frequency signal.

The Field of application of such vortex flow meters extends primarily on applications in the chemical industry, the pharmaceutical Industry, the paper industry or the food and beverage industry, for example, a continuous measurement of the quantity or Volume flow in pipelines of the water / wastewater area of manufacturing facilities.

Devices for flow and quantity measurement in such closed pipes divided into flowmeters (e.g., Coriolis mass flowmeters) and here Volumetric meter or volumetric meter of interest (e.g., vortex flowmeters).

Vortex flowmeter have been well known for many years and serve primarily the quantitative measurement of liquids, Gases and vapors as flowable media in closed pipes. Vortex flowmeters work after the physical principle of the Kármán vortex street, at the vortex frequency is measured after an inflicted interfering body. Meets namely a streaming one Medium on an obstacle, pressure fluctuations in the medium, the to vortex shedding lead to the obstacle. This phenomenon make use of vortex flowmeter. About the geometrically defined Sturgeon bodies become vortex shedding in the Flow meter generates its frequency with the downstream Sensor to be detected. The sensors are usually either in one fixed distance behind the bluff body positioned or directly on the bluff body.

From the DE 298 09 463 U1 For example, a vortex flowmeter operating according to the above-described method with a bluff body and at least one sensor element and with an electronics unit for processing and forwarding the sensor signals, in which a one-piece housing is provided, in which a bluff body and the electronics unit are accommodated.

One Disadvantage of this flow measurement is that at possibly occurring measurement errors no indication or no measure is given, which describes the accuracy of the measurement and thus, if necessary occurring disturbances recognized late become. It is only the frequency as the only source of information used, whereby important information contained in the measured signal remain unused, which can be used for example for a fault detection.

It is therefore the object of the present invention, a method to the reliable Vortex flow measurement of the kind specified above to further improve that a more reliable measurement and / or a fault detection which is also a measure of the accuracy of the measurement performed can specify.

A Another object of the present invention is to provide a vortex flowmeter with means of implementation to provide the above-mentioned method.

A The object is based on a method for reliable vortex flow measurement according to the generic term of claim 1 in conjunction with its characterizing features and by a vortex flowmeter according to the preamble of claim 9 solved in conjunction with its characterizing features.

The dependent claims give advantageous developments of the invention again.

The Invention includes the technical teaching that a method for reliable vortex flow measurement between swirling and evaluating additionally the step Capture an amplitude signal to a reliable measurement and / or a fault detection provide.

The advantage of the solution according to the invention lies in the fact that in this way the entire information of a measured signal is utilized and thus by the additional measurement of the amplitude or the amplitude signal, a plausibility check of the measured frequency signal can be performed. In addition, a measure of the accuracy of the measurement can be obtained by the additional measurement of the amplitude. In particular, it is utilized that the amplitude A is proportional to the square of the measured frequency f according to the following formula: A ~ f 2 ,

Thus, if amplitude information or - signal and frequency information or signal do not agree plausibly, be closed to the presence of disturbances such as vibrations.

Advantageous it is that amplitude signal and frequency signal measured in parallel be to combine the entire signal of a fluid swirled together to capture. Parallel means in this sense that the data is the same Place and / or measured at the same time. Hereby is one Real-time verification of the measured frequency signal possible and it can always be the current measured value or actual value a degree of accuracy can be specified. Thus, appropriate intervention measures due to a possible Perform the fault as soon as possible.

Out For this reason, it is advantageous that the step evaluate the Steps identify the detected signal and / or determine the accuracy of the measurand from the detected signal to realize a reliable evaluation. Because of these steps lets just a plausibility check measured Values according to the above Perform relation.

Further it is preferred that for identifying at least one detected Signals - Frequency and / or Amplitude signal - on for the corresponding signals for signal identification suitable method is used, selected from the group comprising a fast Fourier transform method (FFT-fast Fourier transform), a neural network method Periodogram method, a Bayesian spectrum analysis method and / or a Bayesian parameter estimation method, to take advantage of all the signal information of the fluid.

On that way to deal with existing and known as well as proven procedures reliable Perform measurement or measured value determination. At least regarding the Frequency measurement, no costly new procedures are necessary their reliability first has to be tested. Rather, it can rely on existing gauges use the methods described above, if necessary with minor modifications, which the amplitude signal measurement enable or simplify.

Farther It is advantageous that for determining the accuracy of the measured variable from the at least one detected signal uses a suitable method will be chosen from the group comprising a method for determining the line width in a Fourier spectrum and / or a method for determination the standard deviation of Bayesian parameter estimation to obtain a reliable, the to ensure the entire signal information exploiting provision. With this method in conjunction with the previously listed methods let yourself Thus, without much effort a more reliable measurement carry out.

It is further advantageous that the step further evaluate the Step evaluating and outputting a measurement uncertainty value includes. Based on this measurement uncertainty value can quickly in case of disturbances in the measuring procedure be intervened and necessary countermeasures be initiated. In addition, it can be estimated how serious an optional fault is. That's how it works minor disturbances, the under circumstances Only occur in the short term, unnecessary Avoid interference. On the basis of the measurement uncertainty value can be correct or estimate the measured data accordingly.

Especially It is advantageous that the step of evaluating and issuing a Uncertainty value the step evaluating and outputting the current one Uncertainty value includes. Due to the output of the current Measurement uncertainty value immediately under real-time conditions in the measurement process intervention.

One particular advantage of the invention provides that the step output of a measurement uncertainty value, the step providing the measurement uncertainty value according to one default standard, selected from the group comprising GUM standard and / or SEVA standard.

Thereby let yourself in the novel process according to the present invention Invention use a previously known standard, so this novel methods with already older ones Standards without costly modifications is usable.

The Invention includes continue the technical teaching that in a vortex flowmeter to the reliable Vortex flow measurement comprising means for introducing and flowing through a Fluids in a vortex flowmeter, means for swirling the Fluids, means for detecting the frequency signal of the swirling Fluids and means for evaluating and outputting the detected frequency signal between the means for swirling and the means for evaluating for detecting the amplitude signal in addition means for detecting the Amplitude signal are arranged to additionally with the swirled Evaluate fluid afflicted or generated amplitude signal.

These Means can be introduced particularly advantageously into already existing vortex flowmeters, so that existing vortex flowmeters are easy to upgrade.

Especially it is advantageous that the vortex flowmeter following means comprises: a closed measuring body, through which a to be measured Fluid flows, one arranged in the measuring body Disruptive body, which streamed by the fluid and the fluid is fluidized, at least one in the flow direction downstream sensor which detects the signals generated by the bluff body, wherein the signals are a frequency signal and / or an amplitude signal comprise, and at least one coupled to the sensor evaluation unit, in which the first signal is evaluated and / or output. In this case, the at least one sensor can be designed such that he is suitable both a frequency signal and an amplitude signal capture. It can However, at least two sensors may be arranged, wherein the one of the two sensors the frequency signal and the other sensor detects the amplitude signal.

Further the invention improving measures will be described below together with the description of a preferred embodiment closer by the single figure shown. The figure shows a vortex flow meter with means to carry out a reliable method Vortex flow measurement.

The figure description according to the figure is a vortex flowmeter 1 with a housing, which is designed here as a closed measuring tube.

According to the figure, a closed measuring tube is a flowable medium or a fluid 2 flows through. Inside the measuring tube is a disruptive body 3 arranged, which of the fluid 2 is flowed, so that subsequently in the fluid 2 Forming a vortex. The frequency f of the vortices thus formed is determined by a downstream sensor in the flow direction 4 detected. The vortex frequency f is particularly dependent on the viscosity and Reynolds number of the fluid 2 as well as the flow velocity. The from the sensor 4 recorded vortex frequency f goes to a downstream electronic evaluation unit 5 on the input side to which of these, via known mathematical relationships, an electrical signal corresponding to the volume or volume flow 6 generated.

The relative position between measuring tube and bluff body 3 as well as the relative position between measuring tube and sensor 4 can be in this embodiment in the axial direction, ie in the flow direction of the fluid 2 , to optimize the electrical signal, ie to ensure a maximum amplitude A. The maximum amplitude A is - as explained above - depending on the fluid mechanical conditions of the fluid 2 ,

The disruptive body 3 and the sensor 4 are each associated with tappets 7a respectively. 7b to an actuator 8th coupled. At the actuator 8th These are two combined to form a unit electric linear actuators, which each have a plunger 7a respectively. 7b are assigned to the position of bluff body 3 and sensor 4 to change in the axial direction. For this purpose, both plungers 7a and 7b through a slit-like wall opening 9 performed in the measuring tube, which with known sealing measures leakage of the fluid 2 from the measuring tube or vortex flowmeter 1 prevented to the atmosphere.

The actuator 8th is part of a control loop to maximize signal amplitude, its control unit 10 on the input side with the sensor 4 is connected to the actual value detection. The control unit 10 is an integral part of the electronic evaluation unit 5 which can be designed for example as a programmable logic controller. The maximization of the signal amplitude in the sense of a signal-optimizing change in the relative position between the measuring tube and the interfering body 3 or measuring tube and sensor 4 takes place automatically.

Schematically, the detected signal 6 shown in a two-axis diagram. The amplitude of the signal 6 or the amplitude signal A and the (vortex) frequency f of the signal are marked accordingly.

The invention is not limited to the preferred embodiment given above. On the contrary, modifications are also conceivable which make use of the scope of protection of the following claims. It is also possible, for example, a signal-optimizing change in the relative position between the measuring tube and bluff body 3 or measuring tube and sensor 4 in the radial direction. This can be done by a corresponding up and down movement of the plunger 7a respectively. 7b respectively.

1

Vortex flowmeter

2

fluid

3

disturbing body

4

sensor

5

electronic evaluation

6

(Electrical) signal

7, 7a, 7b

tappet

8th

actuator

9

wall opening

10

control unit

f

(Vortex) frequency (signal)

A

Amplitude (-nsignal)

Claims (10)

A method of reliable vortex flow measurement comprising the steps of: - introducing and passing a fluid ( 2 ) through a vortex flowmeter ( 1 ), - swirling the fluid ( 2 ) by means of at least one disruptive body ( 3 ), - detecting a frequency signal (f) of the swirling fluid ( 2 ) and - evaluating and outputting the detected frequency signal (f), characterized in that, between swirling and evaluating, the step of detecting an amplitude signal (A) takes place in order to provide reliable measurement and / or fault detection. A method according to claim 1, characterized in that amplitude signal (A) and frequency signal (f) are measured in parallel to the entire signal 6 a swirling fluid together. Method according to one of claims 1 or 2, characterized in that the step of evaluating the steps identifying the detected signal 6 and / or determining the accuracy of the measurand from the detected signal 6 includes in order to realize a reliable evaluation. Method according to one of the preceding claims 1 to 3, characterized in that for identifying the detected signal 6 for the measurement of the frequency and amplitude signal (f, A), a method suitable for each signal (f, A) for signal identification is used, selected from the group comprising a fast Fourier transformation method (FFT-fast-Fourier-transform) , a neural network method, a periodogram method, a Bayesian spectrum analysis method and / or a Bayesian parameter estimation method in order to obtain the total signal information of the fluid ( 2 ) exploit. Method according to one of the preceding claims 1 to 4, characterized in that for determining the accuracy of the measured variable from the detected signal ( 6 ) a suitable method is used, selected from the group comprising a method for determining the linewidth in a Fourier spectrum and / or a method for determining the standard deviation of the Bayesian parameter estimation in order to obtain a reliable determination that exploits the entire signal information guarantee. Method according to one of the preceding claims 1 to 5, characterized in that the step further evaluating the Step Evaluate and output a measurement uncertainty value includes. Method according to Claim 6, characterized that the step evaluating and outputting a measurement uncertainty value includes the step of evaluating and outputting the current measurement uncertainty value. Method according to one of claims 6 or 7, characterized that the step outputting a measurement uncertainty value is the step Providing the measurement uncertainty value according to a predetermined standard selected from the group comprising GUM standard and / or SEVA standard. Vortex flowmeter ( 1 ) for reliable vortex flow measurement comprising means for introducing and passing through a fluid ( 2 ) in a vortex flowmeter ( 1 ), Means for fluidizing the fluid ( 2 ), Means for detecting the frequency signal (f) of the fluid ( 2 ) and means for evaluating and outputting the detected frequency signal (f), characterized in that between the means for swirling and the means for evaluating additionally means for detecting the amplitude signal (A) are arranged, in addition to the fluid swirled with the (f) Affected amplitude signal (A) evaluate. Vortex flowmeter ( 1 ) according to claim 9, characterized in that the vortex flow meter ( 1 ) comprises the following means: a closed measuring body through which a fluid to be measured ( 2 ), - a disruptive body arranged in the measuring body ( 3 ), which of the fluid ( 2 ) and this swirl, at least one downstream in the flow direction sensor ( 4 ), which by the Störkörper ( 3 ) detected signals (A, f), wherein the signals (A, f) comprise a frequency signal (f) and / or an amplitude signal (A), and at least one with the sensor ( 4 ) coupled evaluation unit ( 5 ), in which the signal ( 6 ) is evaluated and / or output.