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
  • G01F1/584—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 constructions of electrodes, accessories therefor
• • 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
  • G01F1/60—Circuits therefor

Definitions

• the invention relates to a magneto-inductive flow measuring device, that is to say a device for measuring the volume or mass flow of a medium which flows through a measuring tube in the direction of the measuring tube axis, with a magnet system which essentially comprises a measuring tube passing through the measuring tube. generates transverse to the Meßrohrachse extending magnetic field, with at least one measuring electrode which is in contact with the medium in a defined surface area, and with a control / evaluation, based on the at least one measuring electrode induced measuring voltage information about the volume or mass flow of the medium in the measuring tube.
• Flow measurement is based on the principle of electrodynamic induction: charge carriers of the medium moving perpendicularly to a magnetic field induce a measuring voltage in measuring electrodes arranged essentially perpendicular to the flow direction of the medium.
• the measuring voltage induced in the measuring electrodes is proportional to the average flow velocity of the medium over the cross section of the measuring tube; it is therefore proportional to the volume flow.
• the measuring voltage is usually tapped via a measuring electrode pair, which is arranged in the region of maximum magnetic field strength and where consequently the maximum measuring voltage is to be expected.
• the measuring electrodes themselves are coupled to the medium either galvanically or capacitively.
• the medium to be measured is a medium with a low conductivity, which flows through the measuring tube at a relatively high flow rate. Due to the influence of the relatively large interference voltage on the measurement voltage then there is the danger that the measurement voltage disappears in the noise, whereby a reliable and repeatable flow measurement is impossible.
• the invention has for its object to propose a magneto-inductive flowmeter whose accuracy is largely unaffected by electrochemical interference potentials.
• the object is achieved in that at least the medium-contacting
• the chemically inert and electrochemically and mechanically resistant material is diamond, which is rendered electrically conductive via a suitable doping.
• the diamond material is boron-doped for this purpose.
• a sensor with microelectrodes consisting of diamond has already become known from WO 2005/017514.
• the known sensor serves to determine a chemical property or a chemical process variable of a liquid.
• the sensor consists of a housing, an insulating layer of a non-conductive diamond material, a plurality of microelectrodes of a conductive diamond material, and a circuit connected to each of the microelectrodes. Based on the measured signals recorded by the microelectrodes, the corresponding chemical process variable of the medium is determined.
• the microelectrodes are arranged in a regular or irregular pattern. Preferably, they are integrated into the insulating diamond material so as to be in direct or indirect contact with the medium.
• a synthetic diamond can also be used in connection with the present invention.
• Diamond has the properties that it has on the one hand a high hardness and thus a high mechanical and electrochemical resistance; on the other hand has diamond the advantage that it is largely chemically inert. This eliminates the problem occurring in conventional magnetic inductive flow measuring devices that the actual measurement signals at the measuring electrodes superimposed on a time-varying interference signal, which is caused by variable electrochemical interference potentials at the measuring electrodes.
• the flowmeter according to the invention is characterized by an optimized signal / noise ratio. This makes it possible with the flowmeter according to the invention to determine even low flow velocities of a medium with low conductivity with a sufficiently high reproducibility and accuracy.
• measuring electrodes made of diamond have the advantage that they have a long service life and are extremely low maintenance.
• the magnet system consists of two diametrically arranged electromagnets, wherein the control / off value unit controls the electromagnets so that they produce a periodically alternating or a constant magnetic field in the measuring tube.
• the constant magnetic field over
• an advantageous embodiment of the invention proposes a power supply unit which provides the energy required to operate the flowmeter.
• the energy supply unit is a battery, a solar cell or a fuel cell.
• the energy supply unit is preferably integrated in the transmitter or in the control / evaluation unit of the magneto-inductive flowmeter.
• Fig. 1 a schematic representation of a first embodiment of the device according to the invention
• Fig. 2 a schematic representation of a second embodiment of the device according to the invention.
• Fig. 1 shows a sdiematische representation of a first embodiment of the device according to the invention.
• the measuring tube 2 is flowed through by the medium 11 in the direction of the measuring tube axis 3.
• the medium 11 is at least to a small extent electrically conductive.
• the measuring tube 2 itself is made of a non-conductive material, or it is lined at least on its inner surface with a non-conductive material.
• the perpendicular to the flow direction of the medium 11 aligned magnetic field B is generated via the two diametrically arranged electromagnets 6, 7.
• the magnetic field B is either a constant magnetic field or an alternating field that periodically reverses its direction.
• charge carriers located in the medium 11 migrate according to their polarity to one of the two oppositely poled measuring electrodes 4, 5.
• the voltage which builds up between the measuring electrodes 4, 5 is proportional to the flow velocity averaged over the cross section of the measuring tube 2 Medium 11, ie, it is a measure of the volume flow of the medium 11 in the measuring tube 2.
• the measuring tube 2 is incidentally via connecting elements, for. As flanges, which are not shown separately in the drawing, connected to a pipe system through which the medium 11 passes.
• the measuring electrodes 4, 5 are in direct contact with the medium 11.
• at least the medium-contacting surface area of the measuring electrodes 4, 5 is made of diamond with a suitable conductive doping.
• the medium-contacting surface region of each measuring electrode 6 preferably exists; 7 made of boron-doped diamond.
• the control / evaluation unit 8 is connected via the connecting line 16 with an input / output unit 9 and possibly via a data bus with a parent Connected control room. It goes without saying that the communication can also be carried out by radio.
• the evaluation / control unit 8 is also associated with the storage unit 10.
• Fig. 2 shows a schematic representation of a second embodiment of the device according to the invention.
• the essential difference between the two embodiments is the magnet system used: While electromagnets 6, 7 are used in the embodiment shown in FIG. 1, permanent magnets 17 are used in the embodiment shown in FIG. In both cases, the magnet system is configured and / or arranged such that the electromagnets 6, 7 or the permanent magnets 17 generate a largely homogeneous magnetic field B over the cross section of the measuring tube 2.
• the advantage of the embodiment shown in Fig. 2 with constant magnetic field B is the fact that here a continuous measurement of the volume or mass flow is possible.
• the time that is not available for the measurement after switching the magnetic field is eliminated, and the measuring time can be selected arbitrarily long. In particular, it is optimized so that a desired measurement accuracy is achieved. Due to the optimizable measurement time can therefore be achieved with the device according to the invention best measurement results.
• a constant magnetic field can also be generated via the electromagnets 6, 7.
• a power supply unit 18 is integrated directly into the control / evaluation unit 8.
• the power supply unit 18 is preferably a battery, a fuel cell or u.U. also a solar cell.

Applications Claiming Priority (2)

Publications (1)

Family

ID=38445600

Family Applications (1)

Country Status (6)

Families Citing this family (10)

Family Cites Families (20)

• 2006
  • 2006-05-19 DE DE102006023916A patent/DE102006023916A1/de not_active Withdrawn
• 2007
  • 2007-05-16 RU RU2008150387/28A patent/RU2413182C2/ru not_active IP Right Cessation
  • 2007-05-16 WO PCT/EP2007/054792 patent/WO2007135075A1/de active Application Filing
  • 2007-05-16 EP EP07729240A patent/EP2018523A1/de not_active Withdrawn
  • 2007-05-16 CN CN2007800181753A patent/CN101636640B/zh not_active Expired - Fee Related
  • 2007-05-16 US US12/227,486 patent/US8042410B2/en not_active Expired - Fee Related

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events