WO2014053325A2 - Capteur de température et débitmètre - Google Patents

Capteur de température et débitmètre Download PDF

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Publication number
WO2014053325A2
WO2014053325A2 PCT/EP2013/069441 EP2013069441W WO2014053325A2 WO 2014053325 A2 WO2014053325 A2 WO 2014053325A2 EP 2013069441 W EP2013069441 W EP 2013069441W WO 2014053325 A2 WO2014053325 A2 WO 2014053325A2
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WO
WIPO (PCT)
Prior art keywords
electrode
temperature sensor
face
medium
temperature
Prior art date
Application number
PCT/EP2013/069441
Other languages
German (de)
English (en)
Other versions
WO2014053325A3 (fr
Inventor
Frank Voigt
Werner Wohlgemuth
Günther Bähr
Original Assignee
Endress+Hauser Flowtec Ag
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Filing date
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Application filed by Endress+Hauser Flowtec Ag filed Critical Endress+Hauser Flowtec Ag
Publication of WO2014053325A2 publication Critical patent/WO2014053325A2/fr
Publication of WO2014053325A3 publication Critical patent/WO2014053325A3/fr

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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
    • G01F1/56—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 using electric or magnetic effects
    • G01F1/58—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 using electric or magnetic effects by electromagnetic flowmeters
    • G01F1/588—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 using electric or magnetic effects by electromagnetic flowmeters combined constructions of electrodes, coils or magnetic circuits, accessories therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
    • G01K1/08—Protective devices, e.g. casings
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K13/00—Thermometers specially adapted for specific purposes
    • G01K13/02—Thermometers specially adapted for specific purposes for measuring temperature of moving fluids or granular materials capable of flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K13/00—Thermometers specially adapted for specific purposes
    • G01K13/02—Thermometers specially adapted for specific purposes for measuring temperature of moving fluids or granular materials capable of flow
    • G01K13/026—Thermometers specially adapted for specific purposes for measuring temperature of moving fluids or granular materials capable of flow of moving liquids

Definitions

  • the present invention relates to a temperature sensor according to the preamble of claim 1 and a flow meter according to the preamble of claim 9.
  • EP 2 203 027 B1 discloses a method for monitoring the hazard potential with respect to microbial contamination at a flow meter. It is u.a. the operation of a corresponding temperature sensor discussed in more detail. The temperature sensor should be given time to determine the actual temperature of the ultimately tapped water. EP 2 203 027 B1 proposes to solve this problem to wait a few seconds with the registration of the medium temperature during a medium change. This so-called dead time should, however, be reduced as far as possible during temperature detection during a flow measurement.
  • the invention achieves this object by a temperature sensor having the features of claim 1 and a flow meter having the features of claim 9.
  • a temperature sensor for determining the temperature of a medium has a sensor housing in which a temperature sensor, in particular a resistance thermometer or a thermocouple, is arranged and wherein the sensor housing has a housing head with an end face with a center, wherein the profile of the end face in radial
  • Medium direction means in this context that if the temperature sensor vertically in a tube with a tube axis or another cylindrical container with a
  • the housing has a shape which allows a particularly preferred temperature response in the case of a passing medium.
  • a temperature sensor for determining a temperature of a medium with a housing body and a housing head in which a temperature sensor, in particular a resistance thermometer or a thermocouple, is arranged and which is in particular rotationally symmetrical has a center, the course of the end face in the radial direction to Center first describes a convex course in the medium direction and then a concave profile, wherein the concave curve has a vertex and wherein the distance of the point to the center in the longitudinal axial direction is greater than the wall thickness of the housing head along the longitudinal axis at the midpoint of the
  • the end face has at least one first edge region radially spaced from the midpoint, wherein at least the first edge region defines a first arch curved in the medium direction or a parabolic arched in the medium direction and wherein the housing head is rotationally symmetrical.
  • the arrangement of the center above the arc defined by the edge region is an improved
  • the edge region extends over a radially extending to the center portion of at least 2%, preferably at least 4%, in particular at least 10%, of the diameter of the housing head to ensure a secure fit It is also advantageous if the housing has a cylindrical housing body and the housing head has a protrusion of material, which extends in the radial direction over the
  • This material projection serves to seal the temperature sensor on the medium side when it is arranged in a wall.
  • a particularly high sealing effect to the wall is achieved, provided that the material projection extends at least 10%, preferably at least 20%, of the width of the housing body beyond the outer diameter of the housing body. It is advantageous if the housing head has a groove on the side facing away from the front side. This groove serves to engage in a wall material and allows a further sealing of the temperature sensor in a wall hole.
  • the end face has a cylindrical shape, with a
  • Cylinder wall which in the longitudinal axial direction at least four times, preferably six times, in particular eight times longer than the minimum wall thickness of the cylindrical shape in this area. Due to the cylindrical shape, a well-defined inflow region is ensured on all sides. Possibly.
  • a flow meter has a measuring tube and a device for determining the flow rate and / or the volume flow rate of a medium in the measuring tube, wherein the flow measuring device has a temperature sensor according to claim 1.
  • the temperature sensor can be designed as at least one measuring electrode and / or as an electrode of a filling level monitoring system. This ensures a compact design of the flowmeter. On additional holes in the measuring tube can be dispensed with integration of the temperature sensor in an electrode, wherein the electrode also forms the housing of the temperature sensor.
  • Temperature measuring function from level monitoring.
  • this flow meter may be designed as a magnetic-inductive flow meter, wherein, in addition to the measuring electrodes arranged in the measuring tube, at least one electrode belonging to the filling level monitoring system is preferably arranged. Each of these electrodes can be designed as a temperature sensor according to the invention.
  • Fig.7 partial view of a temperature sensor according to the prior art
  • the temperature sensors shown in FIGS. 1-9 are designed as electrodes and arranged in a measuring tube.
  • the preferably metallic main body of the electrode also forms the housing of the temperature sensor.
  • the following terms electrode body and electrode head are therefore synonymous in the context of this invention for the terms housing body and housing head.
  • the measuring principle of a magnetic-inductive flow measuring device 1, as shown in Fig. 1, is basically known. According to Faraday's law of induction, a voltage is induced in a conductor moving in a magnetic field. Magnetic-inductive
  • Measuring principle corresponds to the flowing medium to the moving conductor.
  • a magnetic field is generated by two field coils not shown on both sides of a measuring tube 2. Perpendicular to this are located on the tube inner wall of the measuring tube, two measuring electrodes 3 which tap the voltage generated when flowing through the medium. The induced voltage is proportional to the flow velocity and thus to the volume flow.
  • the magnetic field built up by the field coils is generated by a clocked DC alternating polarity. This ensures a stable zero point and makes the measurement more insensitive to influences by multiphase substances, inhomogeneity in the liquid or low conductivity.
  • Magnetic-inductive flowmeters with coil arrangements with more than two field coils and other geometrical arrangements are known. In the following, the embodiments illustrated in FIGS. 1-9 will first be described in more detail.
  • FIG. 1 shows a measuring tube 2 with a measurement tube inner wall of a flow measuring device 1 according to the invention which is rotationally symmetrical about a horizontal measuring tube axis S and which in the specific embodiment is designed as a magnetic-inductive flowmeter.
  • the measuring tube 2 has two flanges 2 a, 2 b, which connect to a
  • the outer wall of the measuring tube has a magnet system 2e above and below the measuring tube axis.
  • this coil arrangement generates a magnetic field perpendicular to the measuring tube axis S.
  • two measuring electrodes 3 are arranged which are diametrically opposed and pick up a voltage generated by the measuring medium during operation. If the volume flow is to be measured, it is particularly important that the filling of the measuring tube 2 is as complete as possible.
  • an electrode 4 of a level monitoring system is arranged on the measuring tube axis in horizontal installation at one of the highest points of the inner diameter of the measuring tube 2. This extends through the liner 2d, as well as the metallic measuring tube wall and is fastened to the side of the outer wall of the measuring tube 2 facing away from the medium.
  • FIG. 2 shows a fastening device 81 for fastening the temperature sensor 4.
  • This fastening device 81 has a multipart, in particular rotationally symmetrical housing 82 with a housing longitudinal axis, which is seated on the wall of the measuring tube and fixed thereto.
  • the electrode 4 itself has a rotationally symmetrical electrode body 14 and a rotationally symmetrical electrode head 15 with a center M and a longitudinal axis A. On the electrode body 14, a thread is arranged, in which the union nut 20 can attack.
  • the electrode also has at the electrode head a preferably radially encircling sealing strip or a material protrusion or a Auskrempung, which in the radial direction from
  • Center M extends beyond the diameter of the electrode body 14 addition.
  • the metallic electrode body of the temperature sensor serves as the housing of the
  • Electrode body and electrode head are therefore synonymous in the context of this invention for the terms housing body and housing head.
  • the fastening device has a one-piece
  • This fastening device has a compact construction.
  • FIG. 3 shows a detailed view of a first embodiment of an electrode, as it was shown as MSÜ electrode in FIGS. 1, 2.
  • Fig. 4 shows a second preferred embodiment variant of an inventive
  • Flow meter which is designed as a magnetic-inductive flow meter 21, with an electrode which can be used in a level monitoring system of a pipe.
  • This electrode which is shown in detail in FIG. 6, can be used in particular for
  • the magnetically inductive flow measuring device 21 shown in FIG. 4 in this case has a measuring tube 22 with a rotationally symmetrical inner tube wall and a horizontal measuring tube axis S.
  • the measuring tube 22 shown in FIG. 4 has asymmetrically formed terminal tube flanges 22a and 22b.
  • the measuring tube 22, like the measuring tube shown in FIG. 1, has a
  • Measuring tube wall which consists of metal, preferably made of stainless steel.
  • the inner wall of the measuring tube also has a so-called liner layer 22d, which extends in Fig. 2 by a perpendicular to the measuring tube axis S extending bore 22 f to the outer wall of the measuring tube 22.
  • the measuring tube also has two diametrically perpendicular to the measuring tube axis S.
  • Magnetic systems 22e with which a perpendicular to the measuring tube axis S magnetic field is generated.
  • two measuring electrodes 23 are arranged diametrically opposite on both sides of the measuring tube 22.
  • Measuring tube 22 is an EPD electrode 24 with an integrated in the electrode body
  • FIG. 5 shows a detailed representation of the positioning of the electrode 24 in the measuring tube 22.
  • the electrode 24 is of rotationally symmetrical construction with a longitudinal axis A and has an electrode body 34 and an electrode head 35.
  • the electrode body 34 has on the edge barbs 40, which lead away from the longitudinal axis A. These barbs engage in the liner material, which is arranged in the bore 22f of the measuring tube 22 and ensure a permanent positioning of the electrode 24 in the measuring tube 22.
  • the electrode body is a temperature sensor, in particular a resistance thermometer or a thermocouple, 25 arranged with a sensor body 31
  • This sensor base body 31 is arranged on the inside of the electrode 24 along an inner wall section of the electrode whose outer wall is bounded by the end face 12 of the electrode head 15.
  • the electrode shape or housing shape of the temperature sensor shown particularly in FIG. 3 has a better temperature response compared to the prior art
  • FIG. 7 can be adapted and optimized both for the EPD electrode or the reference electrode and for the measuring electrodes.
  • the electrode 4 shown in FIG. 3 has the pin-shaped or cylindrical electrode body 14 and the electrode head 15.
  • the electrode 4 is constructed in particular rotationally symmetrical and has the longitudinal axis A.
  • the electrode 4 also has an inner
  • Temperature sensor 5 in particular of the resistance thermometer or the thermocouple, arranged so that the temperature at which a medium on an end face 12 of the
  • Electrode head 15 meets over the material wall of the end face 12 as large as possible and over the shortest possible distance to the temperature sensor, in particular a resistance thermometer or a thermocouple, 5, respectively, the sensor body 1 1, passed.
  • the electrode 4 is shown with a preferred face geometry, respectively geometry of an electrode head.
  • the end face has a first peripheral preferably peripheral edge portion R, whose course a first arc K or a
  • the edge region or edge section R preferably extends over a section running radially to the center M of at least 2%, preferably at least 4%,
  • the edge portion R is between 2-70%, in particular between 10-60% of the diameter d 15 of the electrode head 15th
  • the radial course of the end face will be described in greater detail on the basis of the substantially identical variant E of FIG. 9.
  • the end face up to a point P has a negative slope or a negative gradient running to the center point.
  • the second portion of the end face merges into a third portion Y with a positive slope and finally into a fourth portion X whose course is subsequently defined to the midpoint of a flat surface.
  • the end face shape of the electrode of the variant E of FIG. 9 and FIG. 3 thus has a peripheral portion R in the form of a shoulder, followed by an annular groove Z and finally in the center of a cylindrical shape which limits in cross section through Y and X. becomes.
  • the electrode shape of the variant E shown in FIG. 9, which corresponds to the embodiment of FIG. 3, is distinguished from the other variants shown in FIG. 9 for
  • the end face 12 of the electrode head 4 is preferably at least 1.2 times wider than the diameter dM of the electrode body 14, preferably at least 1.5 times wider, more preferably at least 1.7 times wider.
  • the electrode head has an annular sealing strip or a material overhang or a
  • cylindrical electrode body 14 also extends. The top of the annular
  • Material supernatant 16 forms part of the end face 12 of the electrode.
  • the underside of the annular material projection has a groove 17.
  • the fillet 17 permits a partial material absorption of the liner material arranged on the measuring tube inner wall of the magnetically inductive flowmeter, whereby a sealing effect is achieved and penetration of the medium to be measured into the region between the
  • Electrode body 14 and the measuring tube 2 is prevented.
  • the opening width, ie the maximum distance between the two edges of the groove, at the edges of the groove 17 is preferably between 2-20% of the diameter di 4 of the electrode body, more preferably 5-10% of the diameter d 14 of the electrode body.
  • the front side has an annular groove 18. This means that the end face has a partial area which is below the circular arc K defined by the first edge section
  • Electrode body 14 is arranged towards. Through the annular groove 18, a flow control is achieved, which additionally improves the temperature response of the disposed in the electrode body resistance thermometer 5.
  • the annular groove 18 may preferably be more than 1%, more preferably more than 3% of the diameter d 14 of the electrode body 14.
  • the electrode head 15 In the center of the electrode head, the electrode head 15 has a cylindrical formation 19, wherein the cylinder jacket extends parallel to the longitudinal axis of the electrode body.
  • the inner base surface of the cylindrical formation is preferably at least partially flat and extends perpendicular to the longitudinal axis of the electrode body. This has proven to be particularly favorable in order to achieve the highest possible connection between the temperature sensor or the sensor base body and the wall in the region of the cylindrical formation 19.
  • This base surface is preferably arranged in the medium direction above the first circular arc K, which is defined by the edge regions R of the end face 12 of the electrode head 14.
  • the sensor base body 11 within the temperature sensor or the electrode can have different shapes. So he can, for example, a cylindrical shape, a in
  • Electrode head in the region of the cylindrical shape is preferably less than the inner diameter of the cylindrical shape, preferably less than 50% of
  • Inner diameter of the cylindrical shape in particular between 10 to 40% of
  • the wall thickness u is preferably substantially equal in size both within the area of the cylinder jacket and in the area of the terminal circular area of the cylindrical formation 19 within a tolerance range of 15% of the wall thickness, so that a favorable heat transfer is also provided in the region of the cylinder jacket. Due to these low wall thicknesses, an improved heat transfer to the
  • the inner diameter of the cylindrical formation 19 is preferably smaller than the inner diameter of the electrode body 14, particularly preferably at least 1, 2 times smaller, in particular at least 1, 5 times smaller than the inner diameter of the
  • Electrode body 14 At the electrode head 15, the cylindrical electrode body 14 connects. This has a cylinder wall, with a wall thickness which is preferably less in regions than the inner diameter of the electrode body dn, particularly preferably less than 50% of the
  • the electrode body 14 has a front region, which opens directly into the electrode head and a rear region, which preferably protrudes from the measuring tube 2.
  • the outer wall of the electrode body 14 has a connection point, not shown, for discharging a signal.
  • This may be, for example, a solder pad, which allows a connection of a cable, which is connected to an evaluation unit not shown and evaluates the received or applied voltage or current and outputs a status signal on the filling state of the measuring tube.
  • This takes place in cooperation with, in particular, a second electrode or, for example, with an electrically conductive process connection. The contacting of both electrodes takes place with sufficient filling state via the medium.
  • the electrode material of the aforementioned embodiments is preferably made of steel.
  • the sensor body 1 1 is arranged in the region of the electrode head. This can preferably be done by a temperature-resistant electrically conductive adhesive. Alternatively or additionally, the sensor base 1 1 can also be arranged by a thermal paste on the inner wall of the cylindrical shape. This thermal compound reduces in particular the insulating air volume between the base body 11 and the inner wall of the cylindrical formation 19 of the electrode head 14.
  • the sensor body can also be arranged and held by press fit against the inner wall of the cylindrical formation 19 in the center of the electrode head 14.
  • an electrical lead and an electrical lead in the form of cables depart from the probe body. These are discharged in the longitudinal direction through the interior of the electrode body to the outside and are electrically insulated from each other.
  • a cable guide is arranged for positioning and protecting the cables.
  • thermometers in particular a resistance thermometer or a thermocouple 5 forms.
  • EPD electrodes are usually used to detect an unfavorable partial filling of a measuring tube.
  • Such a partial filling of a measuring tube occurs, for example, in the case of outgassing measuring substances or applications, in particular in the case of fluctuating process pressure, in the event of leaks or in the case of deliberate emptying of the line.
  • a temperature sensor in particular a resistance thermometer or a thermocouple, 5, 25 in the form of a
  • the sensor body 1 1 can also be in the form of a
  • Thin-film element may be formed. Suitable material for a metal wire in the
  • Resistance thermometer is u.a. Nickel or platinum.
  • the resistance value of the temperature sensor used in particular the resistance thermometer or the thermocouple, depending on the measuring tube diameter and possibly also wall thickness of the EPD electrode can be selected.
  • Commercially available resistance thermometers which can preferably be used, have, for example, resistance values of 100, 500 or 1000 ohms.
  • the terminal area of the cylinder cavities in the electrodes shown here, respectively the electrode body also serves the arrangement of Fühlergrund stressesn of temperature sensors, in particular of a resistance thermometer or a thermocouple, which is identical to the temperature sensor, the Fig. 3 are formed.
  • Variants 9 A-C have terminal conical areas in the cavities. These are less preferred than flat end regions, as shown in variant D and E, due to poorer heat transfer. This can be partially offset by a higher amount of thermal grease.
  • the cavities with terminal conical end regions are to be understood as a cylindrical shape in the context of the application.
  • the electrode shown in Fig. 6 has an electrode body 34 and an electrode head 35 and is rotationally symmetrical with a longitudinal axis A.
  • the electrode 24 is shown with a preferred face geometry, respectively, a geometry of an electrode head.
  • the end face has a first edge-side preferably peripheral edge portion R, whose course defines a first arc K or a parabola.
  • This first arc K is determined by radial course of the edge portions R to the center M of the end face 32, in particular by their initial rise, the Center M of the end face 32 is arranged in the longitudinal direction of the electrode 24 above this first circular arc K.
  • the angle ⁇ of the circular arc K defined in this way is preferably less than 170 °, preferably equal to or less than 160 °, in order to achieve a favorable inflow behavior of the medium.
  • the course of the end face 32 in the radial direction to the center M thereby reaches a point P from which an increase of the positive slope takes place, wherein the distance t of the point P to the center M in the longitudinal axial direction is greater than the wall thickness u of the electrode head 35 along the longitudinal axis A at the midpoint M of the electrode 24 and the end face 32nd
  • the edge region or edge section R preferably extends over a section running radially to the center M of at least 2%, preferably at least 4%,
  • the edge portion R between 2-70%, in particular between 10-60%, of the diameter d 3 5 of the electrode head 35th
  • the end face 32 Approximately on one third of the distance between the outermost edge point of the end face 32 and the center M of the end face 32, the end face 32 deviates from the shape of the first arc K, such that the course merges into a second section with a positive steeper slope and finally, in a third section whose course is subsequently defined to the midpoint of a flat surface.
  • the end face shape of the electrode of FIG. 6 thus has a peripheral portion R in the form of a shoulder, followed by a cylindrical shape in the center.
  • the end face 32 of the electrode head 24 is preferably at least 1.2 times wider than the diameter d 34 of the electrode body 34, preferably at least 1.5 times wider, more preferably at least 1.7 times wider.
  • the diameter of the electrode body corresponds to the diameter of the electrode head.
  • the electrode head has an annular sealing strip or a material projection or a Auskrempung, which extends in the radial direction over the wall of the pin-shaped
  • cylindrical electrode body 34 also extends. The top of the annular
  • Material supernatant 36 forms part of the end face 32 of the electrode.
  • the electrode head 32 In the center of the electrode head, the electrode head 32 has a cylindrical formation 39, wherein the cylinder jacket runs parallel to the longitudinal axis of the electrode body 34.
  • Base surface of the cylindrical formation 39 extends perpendicular to the longitudinal axis of the
  • Electrode body This base surface is preferably arranged in the medium direction above the first circular arc K, which is defined by the edge regions R of the end face 32 of the electrode head 34. Since the sensor body 31 is disposed within the cylindrical formation 39, a particularly favorable temperature transfer takes place via the end face 32 on the resistance thermometer 25.
  • the wall thickness u of the electrode head in the region of the cylindrical formation is preferably less than the inner diameter of the
  • cylindrical shape preferably less than 50% of the inner diameter of the cylindrical shape, in particular between 10 to 40% of the inner diameter of the cylindrical
  • the inner diameter of the cylindrical formation 39 is preferably smaller than the inner diameter of the electrode body 34, more preferably at least 1, 2 times smaller, in particular at least 1, 5 times smaller than the inner diameter of the
  • Electrode body 34 is Electrode body 34.
  • Contact surface particularly preferably a gold contact on. At this contact surface or
  • Gold contact may be attached to a non-illustrated cable, which is a
  • the cylindrical electrode body 34 connects. This has a cylinder wall in regions with a wall thickness which is preferably less than the inner diameter of the electrode body d ⁇ , more preferably less than 50% of
  • the electrode body 34 has a front region which opens directly into the electrode head and a rear region, which preferably protrudes from the measuring tube 22.
  • a connection point in this rear region, in particular, the outer wall of the electrode body 34, for discharging a signal.
  • This may be, for example, a solder pad, which allows a connection of a cable which is connected to an evaluation unit, not shown, and evaluates the received voltage or current and outputs as a result a status signal on the filling state of the measuring tube. This is done in cooperation with a second electrode. The contacting of both electrodes takes place with sufficient filling state via the medium.
  • FIGS. 7-9 Further less preferred variants of an electrode form are shown in FIGS. 7-9.
  • the advantageous effect and the advantageous use of the invention are shown in FIGS. 7-9.
  • Level monitoring system can in principle be carried out in all medium-carrying pipes in which a medium flows with at least low conductivity.
  • a medium flows with at least low conductivity.
  • EPD empty pipe detection
  • Temperature detection thereby allows the EPD electrode to perform a resistance measurement in combination with a reference electrode and / or the process connection as a function of the conductivity of the medium.
  • the filling state of the measuring tube can be determined by an evaluation unit, not shown, and to a not shown here
  • Medium temperature can be used.
  • the temperature information can in turn be forwarded to the output unit. To a smaller error of the
  • the MSÜ electrode is cylindrical and has a terminal end face, which projects into the measuring tube.
  • a temperature sensor in particular a resistance thermometer or a thermocouple, 5, wherein the MSÜ electrode with the temperature sensor disposed within the electrode 5, in particular a resistance thermometer or a
  • Thermocouple at the same time a temperature sensor in the sense of the application is.
  • the protrusion of the EPD electrode 4, 24 into the medium has a later response of the EPC to the sequence or a response at a lower degree of filling when mounted horizontally and as intended in the uppermost region in the interior of the measuring tube MSÜ electrode.
  • This can be advantageously counteracted by the end face 12, 32 of the electrode head 15, 35 is coated in sections electrically insulating, while the heat conductivity of the coating 13, 33 should be as high as possible. Due to the partial isolation of the end face 12, 32, in particular in the region of the center of the
  • rotationally symmetrical electrode head 15, 35 there is the medium contacting the electrically conductive regions of the EPD electrode, which are located almost on a plane with the wall of the measuring tube.
  • the EPD function or the onset of partial filling can be detected by a jump in the measured temperature.
  • the condition for this is that the actual medium temperature is known as a reference. This can be detected by a device arranged in the second temperature sensor, in particular a resistance thermometer or a thermocouple. In this case, the electrically insulating coating from the previous section could be dispensed with.
  • the temperature sensor in particular a resistance thermometer or a thermocouple, 5, 25 integrated into the EPD electrode 4, 24, wherein the electrode body 14, 34 and the electrode head 15, 35 at the same time Housing for the temperature sensor, in particular a resistance thermometer or a thermocouple, acts.
  • the reference electrode may have an integrated temperature sensor, in particular a resistance thermometer or a thermocouple, wherein said reference electrode is secondarily to the
  • Medium monitoring is used and sends out a signal that is received by the EPD electrode.
  • This reference electrode can also determine the medium temperature.
  • Inner wall of the measuring tube is arranged so that an incomplete filling is detected immediately.
  • the EPD electrode is arranged on the opposite side of the reference electrode of the measuring tube perpendicular or obliquely to the measuring tube axis on or in the inner wall of the measuring tube.
  • both the reference electrode and the EPD electrode may have an integrated resistance thermometer. It is both the
  • Reference electrode and the EPD electrode arranged at the uppermost point of the tube cross-section offset in the flow direction.
  • the temperatures of the temperature sensors, in particular a resistance thermometer or a thermocouple, of the EPD electrode and of the reference electrode should, in the ideal state, be equalized to the ambient temperature in a time interval.
  • a determined temperature requires a much longer time to adjust to the ambient temperature, so there may be a coating at this point.
  • the temperature measurement by means of both the EPD electrode and the reference electrode makes it possible to compare the measured data and to determine a technical disturbance with non-uniform values.
  • Flowmeter be equipped with a resistance thermometer.
  • the four aforementioned electrodes are arranged in a preferred embodiment of the fifth embodiment to an adjacent electrode at an angle of 90 ° on the circumference of the tube cross-section perpendicular to the pipe axis in the region of the magnet system, wherein the two measuring electrodes are diametrically opposed and the connecting line between the Meßelektorden perpendicular to the main direction of the applied magnetic field.
  • the measuring electrodes may be arranged in the flow direction behind or, more preferably, in front of the EPD electrode and the reference electrode or in the same position along the tube axis as the EPD electrode and the reference electrode.
  • a magnetic-inductive flowmeter is designed for a rotationally symmetrical flow profile.
  • the arrangement of electrodes described above, each with at least one integrated temperature sensor, in particular a resistance thermometer or a thermocouple, allows in certain applications to register deviations from the rotational symmetry during the measurement and to reduce their influence on the measurement results.
  • the aforementioned arrangement of the electrodes would allow to take into account the rotational symmetry of the flow when changing rapidly to a medium with a different temperature. This can be done either by issuing a warning to the presence of a non-rotationally symmetric flow or by a measured value correction. For the latter, however, is an empirical predetermination of temperature distribution dependent
  • Rotation symmetry is already at least detectable via a three-point determination, for example by the EPD electrode and the two measuring electrodes. Generally, that applies with As the number of measuring points along the circumference of the pipe increases, an increasingly better determination of rotational symmetry becomes possible. However, since the aforementioned four electrodes are already provided in measuring devices in this arrangement, there is no need for further structural adaptation of the measuring tube and the electrode symmetry but it can be used on existing proven arrangements.
  • the volume flow of a medium is determined in an electromagnetic flowmeter.
  • a connection between the temperature distribution of the flow in the region of the measuring tube wall and the density distribution of the medium can be determined by numerical simulation and corresponding correction functions can be derived.
  • the electrode shape of both the EPD electrode, the reference electrode and / or the measuring electrodes can be adapted and optimized.
  • Various preferred embodiments of the electrodes are described in more detail below with reference to FIGS. 7-9.
  • the electrodes shown in detail in FIGS. 7-9 are of rotationally symmetrical construction with an electrode body 44, 54 and the electrode head 45, 55 with an end face 12, 32.
  • the electrodes have an inner cylinder cavity 46, 56. Terminal in this cylinder cavity 46, 56, the temperature sensor, in particular a resistance thermometer or a thermocouple, arranged so that the temperature on the end face on the temperature sensor, in particular a resistance thermometer or a thermocouple, 5, 25 can be detected.
  • FIG. 7 shows a first preferred electrode shape of an EPD electrode 41 or reference electrode, which has hitherto already been used in magnetic-inductive flowmeters.
  • This electrode has an arcuate end face 42.
  • the radian measure ⁇ of the circular arc is preferably less than 170 °, preferably less than 160 ° in order to achieve a favorable temperature response for an end face 42 in a circular arc shape.
  • This temperature response is shown in FIG. 9. It can be seen that the circular arc shape of the end face compared to other advanced forms less advantageous Temperature response has.
  • the advantage of this type of electrode is that this electrode has a very low flow resistance.
  • Fig. 8 and 9 are further particularly preferred embodiments of a
  • End face geometry of an electrode respectively an electrode head shown.
  • the embodiments shown in these figures have end faces, each with a first edge-side preferably peripheral edge portion whose course defines a first arc A or a parabola.
  • the course of the end face of these differently shaped electrode heads does not follow the shape of the through which
  • This first circular arc is determined by radial course of the edge portions to the center of the end face, in particular by the initial increase, wherein the center of the end face is arranged in the longitudinal direction of the electrode above this first arc.
  • the center of the end face protrudes from the circular arc.
  • FIG. 8 shows a second preferred electrode shape of an EPD electrode or reference electrode, as a further development of the aforementioned variant.
  • the end face of the electrode has a center. Starting from the points of the end face which are furthest apart from the center of the end face, the course of the end face initially describes a first circular arc shape with a first center point angle. This course preferably extends over an edge portion radially spaced from the center of the end face of at least 10% of the end face,
  • the end face preferably at least 20% of the end face, in particular between 25-60% of the end face.
  • the center of the end face protrudes from the first circular arc shape in the longitudinal direction of the pin-shaped electrode.
  • the illustrated in Fig. 8 specific embodiment of the course of the end face describes a second circular arc shape with a second center angle.
  • the second midpoint angle is smaller than the first midpoint angle.
  • the electrode in Fig. 7 has the front side in the form of a circular arc with a certain radius and angle. In Fig. 8, there are two
  • Curvature change The area around point P could also be considered as a circular arc with a smaller radius and angle range, the center of this circle outside the Electrode would be (concave). Following this, another change of curvature takes place.
  • the upper end face is, for example, in turn formed as a circular arc with the center inside the electrode (convex).
  • the radius is significantly smaller than the radius of the first arc.
  • the angle can be even greater than that of the first arc.
  • the aim of the optimization is to achieve a good coupling of the temperature sensor to the medium, which speaks for a thin wall thickness and a wide intrusion into the medium.
  • Boundary conditions can be derived from considerations of mechanical strength, manufacturability and influence on the flow profile. A corresponding change in curvature from convex to concave can also be found in the
  • FIG. 9 shows further preferred electrode forms of an EPD electrode or reference electrode (variant B-E). As can be seen from the time course of the temperature response, these electrode shapes are preferred over the variant shown in FIG. Also in these embodiments describes the radially spaced from the center of the end face
  • Edge portion of a first circular arc shape with a first center angle In variants B and C, the region of the midpoint M of the end face assumes a second circular arc shape with a second center point angle, which second center point angle is preferably less than a quarter, more preferably less than one eighth of the first center point angle of the first circular arc shape.
  • FIG. 9 also shows two further preferred electrode forms with respect to variants A-C with a cylindrical region of the end face.
  • the course directed to the center of a first edge-side section R defines the electrode, as for example in the case of FIG. 9
  • Embodiment of Figure 3 a first arc. Approximately halfway between the outermost edge point of the end face and the center of the end face, the end face deviates from the shape of the first arc, such that a second portion Z of the end face is arranged below the arc in the longitudinal direction of the electrode. In this second section, the end face preferably has a negative rise to the center. This second portion of the end face merges into a third portion Y with a positive slope, and finally enters a fourth portion X over its course in FIG.
  • connection to the midpoint defines a flat surface.
  • the end face of the electrode forms of the variants BE of FIG. 9 thus have a peripheral portion R in the form of a shoulder, followed by an annular groove Z in variants D and E and finally a cylindrical shape Y and X in the center.
  • the electrode shape of the variant E shown in FIG. 9, which corresponds to the exemplary embodiment of FIG. 3, is distinguished from the other variants shown in FIG.
  • the electrodes of the aforementioned exemplary embodiments can have an insulating coating 13 in a region arranged around the center, in particular in FIGS. 3 and 9, the end face of the cylindrical formation 19 and possibly also its cylinder jacket.
  • a polycrystalline diamond coating which combines a very high thermal conductivity with electrical insulation and is chemically, thermally and mechanically highly resilient.
  • Flowmeter attachable which is completely made of plastic, e.g. Polyethylene, or entirely of metal, e.g. Stainless steel. In the case of the latter, however, sufficient thermal insulation of the temperature electrode to the measuring tube must be ensured, depending on the design of the device.
  • measuring tubes made of metal with an inner lining made of plastic, preferably a plastic inner tube and / or a so-called. Liner. This inner lining allows a thermal insulation between the measuring medium and the metallic tube, whereby a thermal decoupling of the temperature electrode is achieved by the measuring tube. It is important that the electrodes e.g. is isolated by the lining of the "colder" measuring tube, otherwise it leads to larger measuring deviations.
  • a two-electrode arrangement of the fill level monitoring system allows an additional determination of the microbial state of the electrodes in process water.
  • the evaluation unit is designed so that both the determination of the medium temperature and the coating condition of the electrode as well as the determination of the filling state of the Tube is made possible. A separate evaluation unit is therefore not necessary, resulting in a reduction in the space requirement of the level monitoring system.
  • Direct contact means that the electrode in which the temperature sensor is integrated with direct contact to the electrode is free of coating and the electrically conductive areas of the electrode outside of the lining are in contact with the medium.
  • Electrode surface to less than 20%, advantageously less than 50%, in particular less than 90% in contact with the medium. Should the electrode to a lesser extent or in particular no longer be in direct contact with the medium, this can lead to a higher
  • Trace detection function can be detected. Upon detection of this case, it is possible to provide appropriate measures in the common evaluation unit, in particular to issue a warning message regarding the accuracy of the temperature measurement.
  • the fill level monitoring system has an evaluation unit which is designed to monitor the degree of filling of the tube and which evaluation unit emits a warning signal if the degree of filling falls below a limit value, preferably a degree of filling of 55% of the inner tube diameter.
  • a warning signal is always output.
  • a warning signal can already be emitted if the degree of filling drops below 75%, preferably 95%, in particular 98% of the inner tube diameter.
  • this requires a positioning of an EPD electrode or a reference electrode in the upper region of the tube.
  • the selection of a suitable limit value of the degree of filling may depend on the different pipe diameter.
  • the EPD electrode protrudes into the measuring tube by more than one percent of the pipe diameter in relation to the degree of filling than in the case of large pipe diameters. Therefore, a preferred gradual distinction can be made.
  • the limit value of the degree of filling is preferably selected from a range between 55 to 99%.
  • the limit value of the degree of filling is preferably selected from a range of more than 75%.
  • the limit value of the degree of filling is preferably selected from a range of more than 95%.
  • the limit value of the degree of filling is preferably selected from a range of over 99%.
  • the limit value of the degree of filling is preferably selected from a range of over 99.6%.
  • a longitudinal axis (electrode) A longitudinal axis (electrode)

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Fluid Mechanics (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)

Abstract

L'invention concerne un capteur de température (4,24,51,) destiné à être installé dans un tuyau, comprenant un corps de boîtier (14,34,54) et une tête de boîtier (15,35,55) dans laquelle est installée une sonde de température, en particulier un thermomètre à résistance ou un thermocouple (5,25) et qui présente notamment une symétrie de révolution. La tête de boîtier (15,35,55) présente une face terminale (12,32,52) ayant un centre (M), et le tracé radial de la face terminale (12,32,52) en direction du centre (M) passe par un point (P) à partir duquel une pente positive s'accroît, la distance (t) entre le point (P) et le centre (M) dans le sens de l'axe longitudinal étant plus grande que l'épaisseur de la paroi (u) de la tête de boîtier (15,35,55) le long de l'axe longitudinal (A) au centre (M) du capteur de température (4,24,51). L'invention concerne en outre un débitmètre doté du capteur de température décrit.
PCT/EP2013/069441 2012-10-01 2013-09-19 Capteur de température et débitmètre WO2014053325A2 (fr)

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