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

Definitions

• the invention relates to a method and a device for non-contact measurement of a mass or volume flow of an electrically conductive fluid by means of Lorentz force compensation.
• a non-contact electromagnetic measurement method called Lorentz force anemometry is described in DE 102005046910B4.
• the method is used for non-contact inspection of moving in pipes or gutters electrically conductive substances. It is based on the generation of a magnetic field at the location of the flow through a magnet system and on the measurement of the Lorentz force acting on the magnet system by the flow.
• a magnet system which can be used flexibly, a primary magnetic field is coupled into the substance to be inspected, and with a suitable measuring system, the force and moment components arising from the relative movement between the primary magnetic field and the substance to be inspected and acting on the magnet system are detected.
• a disadvantage of this method is that the measurement signal of the resulting Lorentz force in the form of the measured force and moment components depends not only on the speed but also on the magnetic field strength. If the magnetic field strength changes due to temperature variations or aging of the magnetic material, measurement errors will occur.
• the object of the invention is to provide a method and a device with which the abovementioned measurement errors are avoided.
• the object is achieved with a method having the features specified in claim 1 and with a device having the features specified in claim 9 or 12, solved.
• the unknown flow (mass flow or volume flow) vi in the magnetic field to be measured is superposed with a second known flow V2 of an easily handled electrically conductive fluid or a moving electrically conductive solid of known speed.
• the resulting Lorentz force is a superposition of the Lorentz force generated by the unknown flow and the force due to the second known flow or the known velocity of the solid.
• the resulting Lorentz force can be adjusted by a control to a specific, constant value or a time course can be specifically excited.
• An advantageous embodiment provides that the known flow is used to compensate for the Lorentz force that this disappears. For this, the flow must be regulated so that the measurement signal of the Lorentz force measurement becomes zero.
• An advantageous form of movement is the rotational movement, because it runs endlessly.
• the direction of movement of the solid is opposite to the direction of movement of the fluid; the amount depends on the design and the conductivities.
• the flow measurement of the potentially aggressive medium is thus attributed to the measurement of a velocity or an angular velocity outside the fluid.
• the known flow or the known movement can also be used to determine the characteristic curve of the Lorentz force anemometer by determining the size of the output signal of the Lorentz force measurement when the input signal is known. This can be done at any number of points on the characteristic curve. For a linear characteristic at least two points are necessary.
• FIG. 2 shows an arrangement with two additional fluids
• FIG. 3 shows an arrangement with a rotating disk
• Figure 4 shows an arrangement with two rotating discs
• Figure 5 shows an arrangement with a rotating hollow cylinder.
• FIG. 1 shows an arrangement in which the fluid to be examined flows in a tubular or channel-shaped channel 1 with the velocity vi to be determined.
• a further tubular or channel-shaped channel 2 is arranged, which flows through a further fluid whose flow velocity v 2 is.
• Both channels are penetrated by the magnetic field of a magnet 3.
• the unknown flow velocity vi to be determined is superimposed with a second flow velocity v 2 of an easily handled electrically conductive fluid.
• the person skilled in easily manageable electrically conductive fluids, such as electrolytes or low-melting metals and alloys are known. From the known or much easier to be measured flow velocity v 2 and the measured Lorentz force the sought flow velocity vi can be calculated very easily. This purpose is served by an evaluation unit, not shown here, with which the resulting magnetic flux or a Lorentz force caused thereby is determined, which represents a measure of the flow velocity vi to be determined.
• channel 1 and the additional channel 2 may be the same or different.
• the spatial arrangement can be carried out equally horizontally or vertically.
• Figure 2 shows an embodiment in which two further tubular or channel-shaped channels 2.1 and 2.2 are mounted.
• This embodiment is advantageously used for the investigation of arrangements with non-linear field properties.
• FIG. 4 An embodiment in which a moving electrically conductive component in the form of a disk 4 is used instead of a reference flow, is shown in FIG.
• the disk 4 rotates on a rotational axis arranged at right angles to the flow direction of the fluid.
• Figure 4 shows an embodiment in which a rotating disc (4.1) and an additional rotating disc (4.2) are arranged on a common axis.
• a hollow cylinder 5 rotates about a rotational axis arranged at right angles to the flow axis, so that the lateral surface of the hollow cylinder 5 is detected by the magnetic field of the magnet 3.

Landscapes

• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Fluid Mechanics (AREA)
• General Physics & Mathematics (AREA)
• Measuring Volume Flow (AREA)
• Indicating Or Recording The Presence, Absence, Or Direction Of Movement (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=47046545

Family Applications (1)

Country Status (3)

Cited By (1)

Families Citing this family (3)

Citations (10)

Family Cites Families (9)

• 2011
  • 2011-09-22 DE DE102011114506A patent/DE102011114506A1/de not_active Withdrawn
• 2012
  • 2012-09-21 JP JP2014531250A patent/JP6117213B2/ja active Active
  • 2012-09-21 DE DE112012003952.1T patent/DE112012003952B4/de not_active Expired - Fee Related
  • 2012-09-21 WO PCT/EP2012/068685 patent/WO2013041694A1/de active Application Filing

Patent Citations (11)

Non-Patent Citations (1)

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