UA94908C2 - Ultra-sonic flow rate meter - Google Patents

Abstract

In the claim ultrasonic flow rate meter is described that has continuous-flow for measured medium measuring tube (1) that in cross section has two halves and two pairs (2) of ultrasonic transformers to each of which ultrasonic reflector (4) is related, at that ultrasonic transformers (3) of each pair (2) are placed at common for those half of measuring rube (1) with shift one with respect to another in longwise direction of measuring tube (1), and ultrasonic reflector (4) relates to respective pair (2) of ultrasonic transformers placed at the other half and located, in longwise direction of measuring tube (1) between both ultrasonic transformers (3) in such way that ultrasonic signal emitted by one ultrasonic transformer (3) of pair (2) of ultrasonic transformers comes to the other ultrasonic transformer (3) by V-like pass (5) of propagation of signal through ultrasonic reflector (4) related to that pair (2) of ultrasonic transformers. In the invention it is proposed to place first pair (2) of measuring transformers and second ultrasonic reflector (4) at one half, and the second pair (2) of ultrasonic transformers and first ultrasonic reflector (4) – at the other half of measuring tube. This leads to increase of accuracy of measurements carried out by ultrasonic flow rate meter (fig. 1)

Description

signal propagation. However, studies have shown that measurement errors, which are about 0.15 905, still occur.

Based on the above, the invention is based on the task of creating a similar ultrasonic flowmeter, which, when determining the flow rate, will allow to almost completely exclude the influence of tangential and radial flow disturbances on the measurement results.

In the design of the ultrasonic flowmeter considered above, this problem is solved due to the fact that the first pair of measuring transducers and the second ultrasonic reflector are located on one half of the measuring pipe, and the second pair of ultrasonic transducers and the first ultrasonic reflector are located on the other half of the measuring pipe.

In other words, the invention provides for the arrangement of pairs of ultrasonic transducers on opposite sides in such a way that the ultrasonic signals of one pair of ultrasonic transducers are sent to the moving medium from one side, and the ultrasonic signals of another pair of ultrasonic transducers are sent from the other side. The basis of this new scheme is the conclusion that the measurement errors that remain after removing the influence of tangential and radial flow perturbations are due mainly to the fact that these perturbations are not constant in the axial direction. Due to the proposed arrangement of the signal propagation paths, measurement errors due to such variability can be practically completely eliminated, as explained below.

It should be noted here that the location of the ultrasonic transducer or reflector "on" one or the other half of the measuring pipe implies such a scheme that enables the transmission, reception or reflection of ultrasonic signals in the area of the inner wall of the measuring pipe.

In addition, "M-shaped" signal propagation paths are understood to mean any such shapes of signal propagation paths, which are achieved by the arrangement of the ultrasonic transducers of a corresponding pair of ultrasonic transducers, looking in the direction of flow, with an offset relative to each other, as well as the arrangement of the ultrasonic reflector in the located between them, looking in the direction of the flow, place. In particular, the M-shaped form of the signal propagation path does not imply the mandatory presence of a certain angle between the two sides of "U", as well as the mandatory equality of the lengths of these sides.

In principle, an option is possible in which both M-shaped paths of signal propagation pass in the same plane. However, the best embodiment of the invention provides for the possibility of passing both M-shaped paths of signal propagation in different planes. In addition, it is preferable that the specified different planes do not intersect inside the measuring tube. At the same time, the variant in which these different planes run parallel to each other is particularly preferred.

The advantages of the invention discussed above are achieved even with the presence of only two pairs of ultrasonic transducers. However, a better variant of the invention provides for the possibility of using at least one additional pair of ultrasonic transducers with an ultrasonic reflector associated with it to implement one more M-shaped signal propagation path. At the same time, it is particularly preferable to use several such additional pairs of ultrasonic transducers in order to implement one M-shaped signal propagation path in several separate and preferably parallel planes, and the ultrasonic transducers that specify adjacent signal propagation paths must be located on different halves of the measuring pipe. Thus, looking in the radial direction of the measuring tube, we obtain a set of M-shaped paths of signal propagation, the solutions and vertices of which are located alternately on one and the other half of the measuring tube.

In the best embodiment of the invention, two ultrasonic reflectors can be located, looking in the longitudinal direction of the measuring pipe, at a distance from each other, not exceeding the maximum distance between two ultrasonic transducers of a pair of ultrasonic transducers. At the same time, the variant in which all ultrasonic reflectors are located, looking in the longitudinal direction of the measuring pipe, on the same section of the measuring pipe, is particularly preferable.

Along with the problem of the invention considered above, the problem of equipping the ultrasonic flowmeter with a diagnostic function that allows you to conclude whether the measurement process is proceeding correctly often also arises.

In the design of the ultrasonic flowmeter considered above, this problem is solved due to the fact that the ultrasonic flowmeter contains a third pair of ultrasonic transducers with an ultrasonic reflector associated with it to implement an M-shaped signal propagation path that passes in a plane that intersects two other propagation planes inside the measuring pipe signal

In other words, according to the invention, this solution involves the use of a third signal propagation path, which in any case passes at such a non-zero angle with respect to the other two planes, to cross these two signal propagation planes in the area of the moving medium flow. This allows, for example, to obtain such a diagnostic function, with the help of which it is possible to detect the presence of impurities that have accumulated at the bottom of the measuring pipe.

In particular, the consequence of such an accumulation of impurities can be a shift of the point on the pipe where the signal is expected to be reflected to the middle of the measuring pipe, which also shortens the length of the path of the acoustic signal.

Therefore, if in the process of measurements, a decrease in the signal transit time is detected in the third plane, which intersects the other two planes, this may serve as a sign of unwanted deposition of pollutants. In addition, the location of the third M-shaped path of signal propagation in a plane that intersects two other planes inside the measuring pipe can also be used as an additional means of measuring the flow of the medium to further increase the accuracy of the flow measurements.

At the same time, in the best embodiment of the invention, the two specified other planes may not intersect inside the measuring pipe. At the same time, the variant in which the two specified other planes run parallel to each other, and the third plane runs perpendicular to them, is particularly preferable. In this case, it is preferable that the third plane passes through the longitudinal axis of the measuring pipe.

In the best separate embodiment of the invention, the ultrasonic flow meter can also contain a fourth pair of ultrasonic transducers with an associated ultrasonic reflector to implement an M-shaped signal propagation path that passes in a plane that intersects the first two signal propagation planes inside the measuring pipe, and the third plane and the fourth plane pass relative to the first plane and the second plane at an angle other than 90", and are not parallel to each other. Thus, the range of the diagnostic function described above can be extended to several controlled signal reflection points.

Other preferred separate embodiments of the invention are similar to the embodiments of the invention discussed above with respect to the first object of the invention, in particular, as regards the use of several additional pairs of ultrasonic transducers, provided, in particular, for obtaining M-shaped paths of signal propagation in different planes, which preferably pass parallel to each other.

Finally, the invention also relates to an ultrasonic flowmeter comprising a flow-through measuring pipe for the medium to be measured, which, when viewed in cross-section, has two halves, and two pairs of ultrasonic transducers, each of which is associated with an ultrasonic reflector, the ultrasonic transducers of each pair being located at common to them half of the measuring pipe with displacement relative to each other in the longitudinal direction of the measuring pipe, and the ultrasonic reflector, correlated with the corresponding pair of ultrasonic transducers, is located on the other half and placed, looking in the longitudinal direction of the measuring pipe, between both ultrasonic transducers in such a way that an ultrasonic signal sent by one ultrasonic transducer of a pair of ultrasonic transducers reached the other ultrasonic transducer along an M-shaped path of signal propagation through an ultrasonic reflector associated with this pair of ultrasonic transducers chiv

As noted above, ultrasonic transducers are usually placed in sockets or pockets that can be located in the wall of the measuring pipe. The problematic point is that in the case of measurements in gases with liquid fractions, these fractions are deposited in the transducer sockets, which can lead to problems there. If, for example, a drop of water settles in the transducer socket, then under certain conditions this drop can form a bridge between the ultrasonic transducer and the measuring pipe, which leads to the unwanted introduction of acoustic energy emitted by the transducer into the measuring pipe, which, in the absence of such bridges, is largely acoustically isolated from the measuring pipe.

Thus, another problem of the invention is solved by creating a similar ultrasonic flowmeter, which would eliminate the problem described above.

In the design of the ultrasonic flowmeter discussed above, this problem is solved due to the fact that the measuring pipe has such an orientation that the ultrasonic transducers of a pair of ultrasonic transducers are located higher than the ultrasonic reflector associated with this pair.

Thus, the invention provides the possibility of tilting the nests or pockets provided for ultrasonic transducers into the inner space of the measuring pipe in such a way as to ensure the automatic emptying of these nests or pockets from liquid and pasty media. In principle, this approach can be used in conjunction with any of the embodiments of the invention discussed above.

In a preferred separate embodiment of the invention, the ultrasonic flowmeter contains at least one additional pair of ultrasonic transducers with an associated reflector to implement another M-shaped signal propagation path that passes in a plane that does not cross the plane of the first M-shaped signal propagation path inside the measuring pipe , and the ultrasonic transducers of an additional pair of ultrasonic transducers are located higher than the ultrasonic reflector associated with this pair.

At the same time, the best option is that the specified planes run parallel to each other, and pairs of ultrasonic transducers are located on one half of the measuring pipe, and ultrasonic reflectors are located on the other half of the measuring pipe. Thus, the aforementioned automatic emptying of nests or pockets for ultrasonic transducers is achieved even in the presence of several M-shaped paths of signal propagation.

Brief description of the drawings.

Below, the invention is considered in more detail with reference to the drawings, which show: in fig. 1a and 16 is a schematic view illustrating the implementation of an ultrasonic flowmeter in the first preferred embodiment of the invention, in fig. 2a and 26 is a schematic view showing the arrangement of the signal propagation paths in the ultrasonic flowmeter made in the first preferred embodiment of the invention in comparison with the state of the art in fig. 36 is a schematic diagram of an ultrasonic flowmeter in the second best embodiment of the invention, in fig. 4a and 46 are a schematic representation of an ultrasonic flowmeter in the third preferred embodiment of the invention, and in fig. 5 is a schematic representation of an ultrasonic flowmeter in the fourth preferred embodiment of the invention.

Implementation of the invention.

In fig. and 16 presents the ultrasonic flow meter in the first preferred embodiment of the invention, schematically shown in a cross-section and in an axonometric projection, respectively. The drawings show only the components of the ultrasonic flowmeter essential from the point of view of the invention, namely the measuring pipe 1, flowing for the measured medium, not marked in the drawings, and several pairs 2 of ultrasonic transducers 3, and an ultrasonic reflector 4 is associated with each pair of 2 ultrasonic transducers. pairs of 2 ultrasonic transducers are located alternately on one and the other half of the measuring pipe 1 in such a way that the signal propagation paths 5 between the two transducers of each pair are in parallel planes. Thanks to this alternation of pairs of 2 ultrasonic transducers and, accordingly, ultrasonic reflectors 4 on one and the other side of the measuring tube 1, the corresponding M-shaped paths of signal propagation are turned by their solutions alternately to one and the other side. At the same time, it should also be noted that the inner wall of the measuring tube acts as an ultrasonic reflector 4 for the signal propagation path 5, which passes inside the measuring pipe, that is, a separate ultrasonic reflector is not needed.

This is also schematically represented in fig. 2a and 26. In fig. 2a in plan view shows a prior art example in which a single M-shaped signal propagation path 5 or multiple M-shaped signal propagation paths 5 is provided, all of which, however, are facing solutions to the right. In contrast to this scheme, in fig. 26 schematically shows the location of the signal propagation paths 5 as implemented in the first preferred embodiment of the invention presented in fig. and 16, namely in such a way that at least one signal propagation path 5 faces its solution to the right, and another signal propagation path 5 faces its solution to the left. Studies have shown that such a solution can significantly increase the accuracy of the measurement.

In fig. According to and 3b, namely in a cross-section and schematically in an axonometric projection, an ultrasonic flowmeter in the second best embodiment of the invention is shown. In this ultrasonic flow meter, pairs of ultrasonic transducers 2 and ultrasonic reflectors 4 are also arranged in such a way as to obtain M-shaped signal propagation paths that pass in parallel planes. In this variant, ultrasonic transducers 3 are additionally provided, located at the top of the measuring tube 1, which determine the M-shaped signal propagation path, which passes in a plane perpendicular to the above-mentioned parallel planes. This plane of signal propagation passes through the longitudinal axis of the measuring pipe 1, thanks to which the inner wall of the measuring pipe 1 can serve as an ultrasonic reflector 4, and a separate device as an ultrasonic reflector is not required. The same applies to the middle plane among parallel planes of signal propagation.

Such a layout allows you to implement a diagnostic function that allows you to determine whether impurities have accumulated at the bottom of the measuring tube 1. As already noted above, due to such an accumulation of impurities, the point at which the signal reflection is predicted must shift to the middle of the measuring tube 1, which also shortens the length of the path of the acoustic signal. If, over time, the signal travel time along a path that crosses other planes of signal propagation decreases, this may indicate unwanted deposition of contaminants. In addition, such an arrangement of the M-shaped path of signal propagation, which intersects inside the measuring tube 1 other planes of signal propagation, can also be additionally used to obtain values of the flow rate of the medium in order to further increase the accuracy of the flow measurements.

In fig. 4a and 46, namely again in cross-section and schematically in an axonometric projection, an ultrasonic flowmeter in the third best embodiment of the invention is shown. Such a layout, as a matter of fact, ensures the achievement of the advantages discussed when considering the ultrasonic flowmeter in the second preferred embodiment of the invention, and unlike the second variant, in this case, the signal propagation planes parallel to each other are crossed by not one, but several other signal propagation planes that pass under at an angle to each other. Although in the considered case one ultrasonic reflector 4 is provided, common to several pairs of transducers, in this way the area of operation of the above-described diagnostic function for detecting contamination of the measuring pipe 1 can be extended to several controlled signal reflection points.

Finally, in fig. 5 schematically shows an ultrasonic flowmeter in a cross-section in the fourth best embodiment of the invention. At the same time, the peculiarity of this variant is that the ultrasonic transducers C are located higher than the ultrasonic reflectors 4 associated with them, due to which the sockets 6, in which the ultrasonic transducers 3 are located, are located with a downward slope. As noted above, this provides automatic emptying of the 6 converter sockets from liquid and pasty media. 3 x 5 it yaz i nar Y la r

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