WO2007012506A1 - Ultrasonic device for determining and/or monitoring the flow of a medium through a pipeline - Google Patents

Abstract

The invention relates to a device for determining and/or monitoring the volume flow rate and/or mass flow rate of a medium (3) which flows through a pipeline (2) in a direction of flow, radiating-in/radiating-out openings (5a, 5b) for ultrasonic measuring signals being provided in the pipe wall (4) of the pipeline (2), which signals are transmitted and received by ultrasonic sensors (6a, 6b) arranged in the direct vicinity of one another, a sound conductor (8) being provided in the region of the outer wall of the pipeline (2), by means of which the ultrasonic measuring signals are passed to the radiating-in/radiating-out openings (5a, 5b) in the pipeline (2) and are coupled into the pipeline (2) and coupled out from the pipeline (2) in such a way that they run through the pipeline (2) along defined sound paths, and having a control/evaluation unit (9), which determines the volume flow rate and/or the mass flow rate of the medium (3) in the pipeline (2) on the basis of the delay time of the ultrasonic measuring signals by a sound entrainment method.

Description

 description

ULTRASONIC APPARATUS FOR DETERMINING AND / OR MONITORING THE FLOW OF A MEDIA 9 BY A PIPELINE

The invention relates to a device for determining and / or monitoring the volume and / or mass flow of a medium flowing through a pipe in a flow direction.

Ultrasonic flowmeters are widely used in process and automation technology for detecting the volume or mass flow of a medium through a pipeline. The medium may be a gaseous, vaporous or liquid medium.

In terms of mounting options, there are two types of ultrasonic flowmeters: in-line ultrasonic flowmeters, which are usually mounted on the pipe via flanges, and clamp-on flowmeters applied to the outside of the pipe and measure the volume or mass flow through the pipe wall, ie noninvasively. Clamp-on flowmeters are described, for example, in EP 0 686 255 B1, US Pat. No. 4,484,478, DE 43 35 369 C1, DE 298 03 911 U1, DE 4336370 C1 or US Pat. No. 4,598,593.

With regard to the measuring methods, two principles can be distinguished: flowmeters which determine the flow over the propagation time difference of ultrasonic measuring signals in the flow direction and against the flow direction, and flowmeters which obtain the flow information from the Doppler shift of the ultrasonic measuring signals , In the case of ultrasonic measuring devices, which operate according to the transit time difference method, the ultrasonic measurement signals are radiated at a predetermined angle via a coupling element in the pipeline in which the medium flows, and emitted from the pipeline. In this case, the ultrasonic sensors are usually arranged such that the sound paths passed through are guided through the central area of the pipeline or of the measuring tube. The determined flow value thus reflects the average flow of the medium in the pipeline.

However, in many applications, especially flow measurements in large diameter piping, this averaging is too inaccurate. Alternatively, it has therefore become known to provide a plurality of pairs of ultrasonic sensors distributed over the circumference on the measuring tube or on the pipeline, as a result of which flow information from various segmented angular regions of the measuring tube or the pipeline is available. The essential component of an ultrasonic sensor is a piezoelectric

Element. The essential component of a piezoelectric element is a piezoceramic layer metallized in at least one partial area. In particular, the piezoceramic layer is a foil or a membrane. By applying an electrical excitation signal, the piezo-ceramic layer is set in vibration and emits an ultrasonic measuring signal with a defined signal shape at an angle of incidence into the pipeline via a coupling element. The reception of the ultrasonic measuring signal after passing through the pipeline takes place in the reverse manner.

The problem in this context is the temperature dependence of the coupling element. This manifests itself in a change in the angle of incidence or the emission angle of the ultrasonic measurement signals into the pipeline or out of the pipeline. In addition, in the known flow meters with diametrically opposed ultrasonic sensors, the wiring complexity is relatively large.

[0008] The object of the invention is to propose a compact, cost-effective ultrasound flow meter.

The object is achieved in that in the wall of the pipe Einstrahl- / Ausstrahlöffnungen are provided for ultrasonic measurement signals emitted or received by ultrasonic sensors which are arranged in the immediate vicinity of each other. Furthermore, a sound conductor is provided in the region of the outer wall of the pipeline through which the ultrasonic measuring signals are routed to the inlet / Ausstrahlöffnungen in the pipeline and coupled in such a way in the pipeline or out of the pipeline, that they the pipe along defined sound paths run through. The sound conductor is - depending on the application - made of ceramic, plastic or metal. Via a control / evaluation unit, the volume and / or the mass flow rate of the measuring medium in the pipeline is determined on the basis of the transit time of the ultrasonic measuring signals according to a sound transmission method.

The advantages of the invention are the following:

It is a compact measuring point;

- The cable cost is low, since the piezoelectric elements are arranged in the immediate vicinity of each other - in the case of using a segmented piezoelectric element or a Sen- sorarrays even sufficient cable.

Since the device according to the invention is a medium-contacting ultrasonic flowmeter, it is ensured that the ultrasonic measurement signals are always perpendicular to the interface between the ultrasonic flowmeter Sound conductor and the medium impact. Therefore, the angle of refraction, which usually has a relatively high temperature dependence, is zero, and the path traveled by the ultrasound measurement signals through the pipeline filled with the medium is constant.

According to an advantageous embodiment of the device according to the invention, the sound conductor is configured and mounted on the pipe wall, that its longitudinal axis is aligned substantially parallel to the longitudinal axis of the pipeline and that the ultrasonic measuring signals, the pipe substantially at an angle of 90 ° is different, go through.

Furthermore, it is proposed to design the sound conductor in such a way and to assemble on the pipe wall that its longitudinal axis is curved with respect to the longitudinal axis of the pipe and that the ultrasonic measurement signals pass through the pipeline on at least one deviating from the radial path sound path. By means of such a sound conductor, arbitrarily designed flowmeters can be designed.

It is considered particularly favorable in connection with the present invention that the ultrasonic sensors are arranged on the sound conductor. It has proven to be advantageous to acoustically decouple the sound conductor from the pipeline.

Moreover, it is provided in the case of using a plurality of sound conductors when the individual sound conductors are acoustically decoupled from each other, so that the influence of an ultrasonic sensor on an adjacent ultrasonic sensor is minimally or completely prevented.

An advantageous embodiment of the device according to the invention provides reflection surfaces provided in the region of the sound conductor, via which the ultrasonic measurement signals from a piezoelectric element to an inlet / outlet opening and are returned. In particular, it can be achieved by this configuration that the ultrasonic measurement signals are coupled into the pipeline without refraction or are coupled out of the pipeline.

Preferably, the device according to the invention is designed so that the

Sound conductor and the ultrasonic sensors form an integral unit. In the case of an ultrasonic flowmeter, the integral unit has at least one seal and is fixedly or removably mounted to the pipeline. According to a preferred assembly technique, the integral unit is in the form of a collar attached to the pipeline.

In particular, the at least one sound conductor is designed such that the temperature-sensitive components of the ultrasonic sensor are thermally largely decoupled from the pipeline. At the temperature-sensitive Components of the ultrasonic sensor are, for example, the piezoelectric elements, soldering and adhesive joints. The thermal decoupling of these elements from the pipeline is preferably realized in that the piezoelectric elements are arranged on spacers, whereby the distance of the piezoelectric to the pipeline is suitably increased.

It is to be regarded as particularly advantageous if the ultrasonic sensors which emit and / or receive the measuring signals are at least one piezoelectric element with at least two electronically controllable regions or at least one electronically controllable sensor array. In particular, the piezoelectric element or the sensor array is acoustically coupled to the sound conductor.

The invention will be explained in more detail with reference to the following drawings. It shows:

1 shows a longitudinal section through a first embodiment of the device according to the invention,

2 shows a longitudinal section through a second embodiment of the device according to the invention,

3 shows a longitudinal section through a third embodiment of the device according to the invention,

4 shows a longitudinal section through a fourth embodiment of the device according to the invention,

5 shows a perspective view of a fifth embodiment of the device according to the invention and

5a: a section according to the marking A-A in Fig. 5th

Fig. 1 shows a longitudinal section through a first embodiment of the device according to the invention 1. The measuring tube 2 with two inlet / outlet openings 5a, 5b can be in the case shown on lateral flanges 1 Ia, 1 Ib in the not shown separately piping. 2 fit. Instead of a measuring tube, it may of course also be a pipe 2 as such, in which at least two inlet / outlet openings 5a, 5b are provided for the ultrasonic measuring signals. The sound conductor 8 is mounted on the measuring tube via a fastening mechanism not shown separately, such that the ultrasound measuring signals emitted or received by the ultrasonic sensors 6a, 6b on the one hand guide the sound conductor 8 and then the medium 3 located in the pipeline 2 to the sound paths indicated by dashed lines go through and that on the other hand no medium 3 can escape via the connecting surfaces between the sound conductor 8 and pipe 2. As usual with the transit time difference method, the ultrasonic sensors 6a, 6b a act alternately as transmitters and as receivers. The ultrasonic sensors 16, 17 and the Sound conductor 8 form an integral unit 18 in the case shown.

The control of the piezoelectric elements 16, 17 of the ultrasonic sensors 6a, 6b via the control / evaluation unit 9, which continue on the basis of the transit time difference in the flow direction and against the flow direction emitted ultrasonic measurement signals the flow of the medium 3 through the pipe. 2 determined.

The sound path, which is traversed by the ultrasonic measurement signals, visualized: The piezoelectric element 17 of the ultrasonic sensor 6b is controlled by the control / evaluation unit 9 and generates an ultrasonic measurement signal with a characteristic waveform. The ultrasonic measurement signal passes through the sound conductor 8 parallel to the longitudinal axis 15 of the measuring tube 2 and is reflected at the reflecting surface 10 so that it is coupled into the pipeline 2 through the inlet / outlet opening 5b. According to the principle of the angle of incidence equal to the angle of reflection, the ultrasonic measuring signal is reflected on the inner wall of the pipeline 2 when it hits the reflecting surface 10e, passes through the inlet / outlet opening 5a into the sound conductor 8 and is detected by the piezoelectric element 16 of the ultrasonic sensor 6a. On the basis of the transit time difference, which have the ultrasonic measurement signals on the previously described and then on the traversed in the opposite direction sound path, the control / evaluation unit 9 determines the flow of the medium 3 through the pipe 2. In the case shown, by the way two separate and acoustically decoupled ultrasonic sensors 16, 17. As already mentioned above, a piezoelectric element 16; 17 are used with at least two electronically controllable areas or at least one electronically controllable sensor array, wherein individual areas of the sensor sorarrays are controlled so that they act as a transmitting or receiving area.

2, a longitudinal section through a second embodiment of the device 1 according to the invention is shown. This embodiment differs from the embodiment shown in Fig. 1 substantially in the arrangement of the ultrasonic sensors 6a, 6b. The ultrasonic sensors 6a, 6b are arranged here in the lower region of the pipeline 2. The ultrasonic measurement signals emitted by the ultrasonic sensors 6a, 6b are reflected at the reflection surfaces 10a, 10b. In this case, the device according to the invention is preferably designed as a sleeve which can be mounted on the pipeline 2.

Fig. 3 shows a longitudinal section through a very compact embodiment of the device according to the invention 1. In this embodiment, the two ultrasonic sensors 6a, 6b approximately centrally located between the two inlet / outlet openings 5a, 5b. A deflection of the ultrasonic measuring signals This is done a first time at the central reflection surfaces 10c, 10d and a second time at the lateral reflection surfaces 10a, 10b.

The embodiment of the device 1 according to the invention shown in Fig. 4 differs from the embodiment shown in Fig. 3 substantially by the greater distance of the ultrasonic sensors 6a, 6b of the pipe 2. About spacers 13a, 13b is a thermal decoupling of piezoelectric elements 16, 17 and the electronics of the flowing through the pipe 2 medium 3 reached.

Fig. 5 shows a perspective view of a fifth embodiment of the inventive device 1. In Fig. 5a is a section according to the marking A-A in Fig. 5 is shown. In this embodiment, the ultrasonic measurement signals are not radially coupled, but quasi decentralized in the pipeline 2 and decoupled from the pipe 2. In combination with the previously shown embodiments, it is thus possible to obtain spatially resolved information about the flow in the pipeline 2.

The longitudinal axis 14 of the sound conductor 8 is bent in a circle. The ultrasonic measurement signals are generated by the two ultrasonic sensors 6a, 6b and deflected at the reflection surfaces 10a, 10b in such a way that they pass through the sound conductor 8 as far as the reflection surfaces 10c, 10d. At the reflection surfaces 10c, 10d, the ultrasonic measurement signals undergo a second deflection and are coupled into the pipeline 2 through the inlet / outlet openings 5a, 5b. Based on the transit time difference between the ultrasonic measurement signals, which pass through the pipeline 2 on the described sound path and the opposite sound path, the control / evaluation unit 9, not separately shown in FIG. 5, determines the flow of the medium 3 through the pipeline 2.

[0034]

[0035] List of Reference Numerals

[0036] 1 ultrasonic flowmeter

2 pipeline

3 medium

4 pipe wall / wall

[0040] 5a inlet opening / outlet opening

[0041] 5b inlet opening / outlet opening

6a ultrasonic sensor

[0043] FIG. 6b ultrasonic sensor

7 outer wall

[0045] 8 sound conductor

[0046] 9 control / evaluation unit 10 reflection surface

10a reflection surface

10b reflection surface

10c reflection surface

10d reflection surface

10e reflection surface

IIa flange

IIb flange

12 sealing ring

13a spacer

13b spacer

[0058] 14 longitudinal axis of the sound conductor

15 longitudinal axis of the pipeline

16 piezoelectric element / sensor array

17 piezoelectric element / sensor array

Claims

claims 1. Device for determining and / or monitoring of the volume and / or Mass flow of a medium (3), which flows through a pipe (2) in a flow direction, wherein in the pipe wall (4) of the pipe (2) Einstrahl- / Ausstrahlöffnungen (5a, 5b) are provided for ultrasonic measurement signals from ultrasonic sensors ( 6a, 6b), which are arranged in the immediate vicinity of each other, are emitted or received, wherein a sound conductor (8) is provided in the region of the outer wall of the pipeline (2) via which the ultrasonic measuring signals to the inlet / outlet openings (FIG. 5a, 5b) are guided in the pipeline (2) and are coupled into the pipeline (2) in or out of the pipeline (2) in such a way that they pass through the pipeline (2) along defined sound paths, and with a regulation / Evaluation unit (9), which determines the volume and / or mass flow of the medium (3) in the pipeline (2) based on the duration of the ultrasonic measurement signals according to a Schallmitnahmeverfahren. 2. Device according to claim 1, wherein the sound conductor (8) configured and mounted on the pipe wall (4), that its longitudinal axis (14) is aligned substantially parallel to the longitudinal axis (15) of the pipe (2) and in that the ultrasonic measuring signals pass through the pipeline (2) substantially at an angle other than 90 °. 3. Device according to claim 1, wherein the sound conductor (8) configured and mounted on the pipe wall (4) is that its longitudinal axis (14) with respect to the longitudinal axis (15) of the pipe (2) is curved and that the Ultrasonic measuring signals through the pipeline (2) on at least one deviating from the radial path sound path. 4. Apparatus according to claim 1, 2 or 3, wherein the ultrasonic sensors (6a, 6b are arranged on the sound conductor (8). 5. Apparatus according to claim 1, 2 or 3, wherein the sound conductor (8) of the Piping (2) are decoupled. 6. Apparatus according to claim 1, 2 or 3, wherein in the case of using a plurality of sound conductors (8), these are decoupled from each other. 7. Device according to one or more of the preceding claims, wherein in the region of the sound conductor (8) reflection surfaces (10a, 10b, 10c, 1Od) are provided, via which the ultrasonic measuring signals are performed. 8. The device according to claim 1, 2, 3 or 4, wherein the sound conductor (8) and the Ultrasonic sensors (6a, 6b) form an integral unit. 9. The device according to claim 5, wherein the integral unit at least one Has seal (12) and is fixed or detachably mounted on the pipe (2). 10. The device according to claim 1 or 4, that the at least one sound conductor (8) is formed such that the temperature-sensitive components of the ultrasonic sensor (6a, 6b) are thermally largely decoupled from the pipeline. 11. The device of claim 1, 4, 6 or 8, wherein it is in the ultrasonic sensors (6a, 6b), the send out the measuring signals / and and receive at least one piezoelectric element (16) with at least two electronically controllable areas or at least one electronically controllable sensor array (17) acts.