Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
  • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
  • G01F15/12—Cleaning arrangements; Filters
  • G01F15/125—Filters
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
  • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
  • G01F1/662—Constructional details

Definitions

• the present invention relates to a gas meter comprising, an ultrasonic measurement conduit with a longitudinal axis comprising an internal part in which the gas flows and at least two ultrasonic transducers spaces along the longitudinal axis
• the subject of the invention is therefore a gas meter comprising, an ultrasonic measurement conduit with a longitudinal axis comprising an internal part in which the gas flows, at least two ultrasonic transducers spaced along the longitudinal axis, characterized in that said counter comprises between each transducer and said internal part of the measurement conduit a portion enlarged with respect to the dimensions of the active surface of said transducer, said counter further comprising at least one element placed in at least one of said enlarged portions and s' extending over the entire internal width of the latter so as to form a filter screen vis-à-vis the dust carried by the gas, said element being traversed by the ultrasonic waves emitted by the transducers over at least part of its width which is greater than the dimensions of the active surface of said transducer
• said at least one element forming a filter screen is placed against the transducer. According to another embodiment of the invention, said at least one element forming a filter screen is placed at a distance from the transducer.
• Said at least one element forming a filter screen can be placed in front of the upstream transducer and / or in front of the downstream transducer depending on the configuration of the counter and, more particularly of the measurement conduit, of the enlarged portions and of the transducers.
• the meter can comprise at least one obstacle positioned longitudinally in the internal part of the measurement conduit so as to form at least one annular passage for the flow of gas.
• the measurement conduit comprises an inlet and an outlet for the flow of gases which are respectively arranged between one of the enlarged portions and said measurement conduit.
• the gas inlet and outlet each have, at the place where the gas flow, respectively, enters and leaves the measurement pipe, a passage section offered to the gas whose normal is inclined relative to the axis longitudinal at an angle other than 90 ° or may also be equal to 90 °.
• the flow is further channeled and the dust which is also channeled with the flow is kept away from the transducers, thereby reducing even the risks of contamination of said transducers.
• the filter screen element is made of a material composed of metallic or synthetic fibers.
• the material can be of the type in which the fibers form a sieve or of the type in which the fibers are intertwined and distributed in a volume.
• the measurement conduit can for example take the form of an ellipsoid of revolution, of a tube or well have a rectangular cross section.
• FIG. 1 is a schematic longitudinal view of an ultrasonic gas meter according to the invention
• FIG. 2 is an enlarged longitudinal view of the measurement conduit and of the ultrasonic transducers shown in FIG. 1 according to a first embodiment
• FIG. 3 is an enlarged longitudinal view of the measurement conduit and of the ultrasonic transducers shown in FIG. 1 according to a second embodiment
• FIG. 4 is an enlarged longitudinal view of the measurement conduit and of the ultrasonic transducers shown in FIG. 1 according to a third embodiment
• FIG. 5 is a partial enlarged view of the enlarged portion 50 shown in FIG. 4,
• FIG. 7 is a longitudinal view of an alternative embodiment of the measurement conduit shown in FIGS. 1 to 4,
• FIG. 8 is an enlarged view of the enlarged portion in which the screen element is placed according to an alternative embodiment of that shown in FIG. 7,
• FIG. 9 is a longitudinal view of a second alternative embodiment of the measurement conduit shown in Figures 1 to 7
• - Figure 10 is a longitudinal view of a third alternative embodiment of the measurement conduit shown in Figures 1 to 9,
• FIG. 11 is a view of the cross section of the measurement conduit shown in FIG. 10,
• FIG. 12 is a longitudinal view of a fourth alternative embodiment of the measurement conduit shown in FIGS. 1 to 9.
• an ultrasonic gas meter comprises a housing 12 to which an inlet opening 14 for the gas flow is connected as well as an outlet opening 16.
• a ultrasonic measurement block 18 is housed inside the housing 12 and comprises a measurement conduit 20 with a longitudinal axis XX ′, for example produced in the form of a tube, at the ends of which two ultrasonic transducers 22, 24 are positioned along said longitudinal axis.
• the gas flow enters through the opening 14 inside the housing 12, splits on the wall of the ultrasonic measuring block 18 located opposite said opening and is distributed in the interior volume between said housing and said ultrasonic measurement block.
• the gas flow is directed towards the lower part of the housing and rushes through an opening 26 made in the measuring block inside the latter.
• the downward movement then the elbow effected by the flow going up towards the opening 26 allows said flow to get rid of a large part of the heavy dust which it conveys.
• the flow then enters the internal part of the measurement conduit 20, in which the ultrasonic measurements of the gas flow will be carried out, by a supply 27 produced in the form of an annular opening, and escapes from said conduit by an outlet 28 also produced in the form of an annular opening.
• the annular inlet and outlet openings have a gas flow section whose normal is inclined relative to the longitudinal axis at an angle which is substantially equal to zero in the example shown in Figures 1 and 2
• the flow comes out of the measuring block 18 upward through a chimney 29 which is arranged perpendicular to said measuring block and which communicates with the outlet opening 16 of the meter.
• the counter comprises, between each ultrasonic transducer 22, 24 and the internal part of the measurement conduit 20 in which the gas flows, a portion 30, 32 which forms a housing and a support for said corresponding transducer.
• each of the annular inlet 27 and outlet 28 openings is arranged between one of said enlarged portions and the measurement conduit 20.
• Each of the portions 30, 32 has an enlarged transverse dimension relative to the transverse dimensions of the surface. activates transducers.
• Each portion has for example a generally cylindrical external shape which has an internal recess 34, 36 also of cylindrical shape and in which the corresponding transducer is mounted.
• Each of the portions has a peripheral flange 38, 40 extending the general cylindrical shape and which provides before each transducer a free space of cylindrical shape 42, 44 which has an enlarged transverse dimension relative to the transverse dimensions of the active surface of the transducers.
• the element 46 is disposed against the transducer and extends transversely over the entire internal transverse dimension or width of said free space so as to form in front of said transducer a screen which acts as a filter preventing the dust transported by the gas d '' reach the transducer.
• the filtering element is for example fixed by gluing on the annular part 32a of the portion 32 situated at the bottom of the free space and surrounding the transducer 24.
• the filter element is made of a material which is formed of metallic or synthetic fibers.
• Each fiber constitutes an obstacle for the dust particles whose trajectory crosses this fiber.
• the filter can be of the sieve type, that is to say that the dust particles are distributed over the almost flat surface of said filter.
• the material is, for example, a stainless steel cloth, the diameter of the metallic fibers is 25 ⁇ m and that of the interstices 16 ⁇ m.
• the filter is able to accumulate a greater quantity of dust than the filter of the sieve type before becoming clogged.
• Such a material is for example cotton or fleece.
• the material is for example the product sold by the company 3M under the brand "FILTRETE 50g”.
• the density of fibers in the material is for example between 10 and 500 g / m 2 and is for example of the order of 50 g / m 2 and its thickness is equal to 2 mm.
• the fiber density in the material is less than 10 g / m 2 then it is found that a very large filter thickness is necessary to obtain sufficient filtering. On the contrary, if the fiber density in the material is greater than 500 g / m 2, then it can be seen that the acoustic signal from the transducers is greatly attenuated, which is unacceptable.
• the size of the fibers is also an important parameter and it is preferable to have fine fibers for the same interstice between the fibers because the porosity of the filter will be higher.
• the cone within which the ultrasonic waves emitted by the transducer 24 are contained î 1 is indicated in broken lines and designated by the reference marked 47 in Figure 2.
• the transverse dimension of the filter element surface 46 is greater than that of the active surface of the transducer and the filter element is, on the one hand, made of a material transparent to ultrasonic waves and, on the other hand, is placed in a
• the filter element when the filter element is placed against the transducer (fig. 2) and the material of the filter element is of the type in which the dust is distributed in a volume, it is possible to increase the thickness or dimension longitudinal of the material while reducing its density so that the ultrasonic waves are not
• the filter element 46 placed in front of the transducer 24 makes it possible to eliminate the turbulences present in the flow which, if they occurred in front of said transducer, would affect the linearity of the measurements.
• a filter element 48 similar to element 46 is placed in the free space 42 of the enlarged portion 30, 32 so as to also protect the transducer 22 against dust. This precaution can be useful when the meter must be subjected to severe dusting tests or when it is planned to use it for the counting of gases deemed to be particularly loaded with dust.
• each of the enlarged portions 50, 52 of generally cylindrical shape includes a peripheral flange 54, 56 extending said generally cylindrical shape and which provides a free space of cylindrical shape in front of each transducer 58 , 60.
• the longitudinal dimensions of the flanges 54, 56 and the free spaces 58, 60 are respectively greater than those of the flanges 38, 40 and the free spaces 42, 44 of FIG. 2.
• the elongation of the internal free spaces with the enlarged portions 50, 52 makes it possible to position each filter element 62, 64 at a distance from the corresponding transducer 22, 24, thus leaving between the filter element and its corresponding transducer an area of the free space where the gas is at rest.
• FIG. 5 is an enlarged partial view of the portion 50 shown in Figure 4 which shows part of this portion, the other part being obtained by symmetry with respect to the longitudinal axis XX '.
• the filter element 62 is pinched between one end of the collar 54 which forms a shoulder 55 and a washer 57 which is secured to said end of the collar, for example by ultrasonic welding.
• FIG. 6 represents an alternative embodiment of the enlarged portion 50 of FIG. 4 in which the flange 66 extends the cylindrical part of the enlarged portion 68 so as to give the free space 70 internal to said enlarged portion a bowl shape gradually flared in the opposite direction to the transducer.
• the filter element 62 is positioned at a distance from the transducer in this flared shape space.
• FIG. 7 illustrates an alternative embodiment of the measurement conduit shown in FIGS. 1 to 4 which here takes the form of an ellipsoid of revolution 72 as described in French patent 2,683,046.
• the ellipsoid of FIG. 7 has a difference in structure from that of French patent 2,683,046: the fluid flow is produced by openings made in the wall of the conduit 72 and not around the transducers.
• Two enlarged portions 74, 76 serving as housings for the ultrasonic transducers 78, 80 each have an internal free space 82, 84 of gradually flared shape in which is placed a filter element 86, 88 similar to those described with reference to FIGS. 4 and 6.
• Two annular openings 90, 92 serving respectively as an inlet and an outlet for the flow of gas in the internal part of the measurement conduit 72 are arranged between each enlarged portion 74, 76 and said measurement conduit. These openings each have at the place where the gas flow, respectively, enters and leaves the measurement conduit 72, a passage section offered to the gas whose normal N is inclined relative to the longitudinal axis XX 'along a angle ⁇ other than 90 °.
• the angle of inclination ⁇ is equal to 45 °.
• an elongated obstacle 94 having for example a general shape of a warhead is positioned on the longitudinal axis XX '.
• This obstacle defines with the internal wall of the measurement conduit an annular passage 96. Thanks to the annular shape of the passage 96 and the orientation of the normal N to the passage sections offered to the gas at the place where the gas flow, respectively, enters and leaves the measurement conduit 72, said gas flow is channeled which keeps the dust it carries on a path away from the transducers 78, 80.
• the filter element 86 placed in front of the upstream transducer 78 is not very dusty, while on the filter element 88 placed in front of the downstream transducer 80 there is a distribution of dust 98 at the periphery of said filter element as indicated in figure 7.
• FIG. 8 shows another possible variant of an enlarged portion 100 usable with the measurement conduit 72 of FIG. 7 in which the free space 102 takes the form of a cylindrical space at the bottom of which the filter element 86 is placed against the transducer 78.
• FIG. 9 illustrates another configuration of ultrasonic counter 110 in which only the measuring block 112 (housed inside an external housing) has been shown and which is described in patent application EP 0 682 773.
• This measurement block includes a tubular measurement conduit 114 provided with inlet 116 and discharge 118 openings, normal to the passage section offered to the gas at the place where the gas flow, respectively, enters and comes out of the measurement conduit 114 forms with the longitudinal axis XX 'an angle of 90 °.
• An improvement compared to this configuration could consist in arranging the openings 116 and 118 according to an inclination forming with the longitudinal axis XX ′ an angle less than 90 ° in order to distance the flow and therefore the dust particles from the zone where are located the transducers.
• An elongated obstacle 120 is positioned along the longitudinal axis inside the measurement conduit 114 to form an annular passage 122 in which the gas flows.
• Two enlarged portions 124, 126 form an angle of 90 ° with the longitudinal axis XX 'and thus allow the ultrasonic transducers 128, 130 housed in these portions to be offset.
• the gas meter 140 partially shown in longitudinal view in FIG. 10 comprises a measurement duct 142 of longitudinal axis XX ′, the cross section of which is shown in FIG. 11 is rectangular. Two portions 144, 146 enlarged relative to the dimensions of the ultrasonic transducers 148, 150 are arranged on one 142a of the walls of the measurement conduit at an inclination relative to the longitudinal axis XX '.
• the transducers 148, 150 are mounted at the bottom of the enlarged portions 144, 146 which serve as their housings and the filter elements 152, 154 conforming to those described with reference to FIG. 4 are positioned at a distance from said transducers in the corresponding cylindrical free spaces 156 , 158.
• the ultrasonic waves emitted by one of the transducers propagate in a V or W-shaped path.
• the two transducers could also be arranged on the opposite wall 142b of the measurement conduit or else one of the transducers can remain on the wall 142a and the other can be mounted opposite on the opposite wall 142b so that the two transducers are connected by a fictitious straight line YY 'perpendicular to their active surfaces and which cuts the longitudinal axis at an angle of inclination of less than 90 ° (Fig. 12). It is also possible to use this configuration of duct of rectangular cross section with the enlarged portions containing the ultrasonic transducers arranged at the opposite ends of said duct.

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• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• General Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Measuring Volume Flow (AREA)
• Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=9524346

Family Applications (1)

Country Status (10)

Cited By (3)

Families Citing this family (12)

Family Cites Families (5)

• 1998
  • 1998-03-19 FR FR9803512A patent/FR2776379B1/fr not_active Expired - Fee Related
• 1999
  • 1999-03-15 HU HU0102221A patent/HUP0102221A3/hu unknown
  • 1999-03-15 KR KR1020007010247A patent/KR20010034606A/ko not_active Application Discontinuation
  • 1999-03-15 EP EP99909008A patent/EP1064522A1/de not_active Withdrawn
  • 1999-03-15 BR BR9908742-1A patent/BR9908742A/pt not_active Application Discontinuation
  • 1999-03-15 CN CN99804004A patent/CN1293754A/zh active Pending
  • 1999-03-15 CA CA002324216A patent/CA2324216A1/en not_active Abandoned
  • 1999-03-15 AU AU28403/99A patent/AU2840399A/en not_active Abandoned
  • 1999-03-15 WO PCT/FR1999/000577 patent/WO1999047896A1/fr not_active Application Discontinuation
  • 1999-03-19 AR ARP990101218A patent/AR018785A1/es unknown

Non-Patent Citations (1)

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