WO1995014217A1 - Procede et appareil d'etalonnage d'un appareil de mesure du niveau d'un liquide - Google Patents

Procede et appareil d'etalonnage d'un appareil de mesure du niveau d'un liquide Download PDF

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Publication number
WO1995014217A1
WO1995014217A1 PCT/FI1994/000513 FI9400513W WO9514217A1 WO 1995014217 A1 WO1995014217 A1 WO 1995014217A1 FI 9400513 W FI9400513 W FI 9400513W WO 9514217 A1 WO9514217 A1 WO 9514217A1
Authority
WO
WIPO (PCT)
Prior art keywords
float
liquid
container
liquid level
measurement
Prior art date
Application number
PCT/FI1994/000513
Other languages
English (en)
Inventor
Ilkka Hapuoja
Kimmo Koivisto
Veli-Matti Hovattala
Mikko Heikkinen
Original Assignee
Aspo Systems Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Aspo Systems Oy filed Critical Aspo Systems Oy
Priority to EP95900159A priority Critical patent/EP0729564A1/fr
Publication of WO1995014217A1 publication Critical patent/WO1995014217A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/0038—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm using buoyant probes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
    • G01F25/20—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume of apparatus for measuring liquid level

Definitions

  • the present invention relates to a procedure and apparatus for the calibration of a liquid measuring apparatus, as defined in the preamble of claim 1.
  • level transmitters providing information about the height of the liquid surface.
  • the magnetostrictive sensor which involves measurement of the position of a float, or the capacitive method (most commonly used), in which the height of the liquid surface is deter- mined by measuring the capacitance of different capacitors relative to each other. Apparatuses like this involve complex electronics and are not sufficiently reliable in operation because certain fuel additives cause disturbances especially in case of the capacitive method.
  • US patent specification 4 914 962 presents a transducer based on the use of a vibrating stripe, which can be used for the measurement of liquid level.
  • the level transducer presened in this specification measures the liquid level by measuring the floating of a weight unit placed at a certain height in the container and partially submersed in the liquid.
  • the frame of the transducer serves as an upper fixing point for a thin steel st-ipe and as a fixing point for a hinge connecting the frame to a lower support which acts as the lower fixing point of the stripe and at the same time as a fixing point for the supporter of the weight unit.
  • a unit Placed near the stripe is a unit consisting of a permanent magnet and a winding, causing the stripe to vibrate at its resonant frequency and to pro ⁇ turn an electric output signal for liquid level measurement.
  • Attached to the supporter is a supporting cable to which the weight unit is attached.
  • the weight unit is a cylindrical body having a constant diameter over the entire range of variation of the liquid level.
  • the apparatus has a good ability to withstand the effects of fuel additives as the float can be manufactured from a material that is immune to the additives.
  • the apparatus can be cali ⁇ brated by measuring the level of the liquid in the container by means of a rod and writing down the level height. After this, the level reading given by the apparatus is compared to the rod measurement. Other calibration methods can be used as well.
  • the object of the present invention is to improve the accur ⁇ acy of a previously known float apparatus designed for the measurement of liquids.
  • the outer surface of the float is provided with points of discontinuity at which the external diameter of the float changes. With the aid of these points of discontinuity, the measurement values determined by means of the float are adapted to the real mechanical measurements of the float in accordance with the claims presented below.
  • the discontinuous float of the invention makes it possible to observe real height points, which ensures that possible move ⁇ ments and other disturbances of the container can be detect- ed.
  • automatic calibration as provided by the inven ⁇ tion is easy to handle mathematically and it can be taken into account in the normal gradual emptying of the container following each filling.
  • the same method can also be employed in connection with the filling of the container by recording the measurement signal at regular intervals of time during filling and analyzing the curve upon completion of filling.
  • Fig. 1 presents the apparatus of the invention for the meas- urement of the level of a liquid fuel in a liquid fuel tank.
  • Fig. 2 presents an adjustment curve in which the discontinui ⁇ ties are visible.
  • Fig. 1 shows a cylindrical liquid fuel tank 1 containing fuel to the height of level 2.
  • a nozzle 3 for a measuring apparatus.
  • a prot ⁇ . *;ive tube 4 extending to the bottom of the tank 1 and secured at its lower end.
  • a cylindrical float 5 Placed inside the tube is a cylindrical float 5 with a closed bottom and extending nearly to the lower end of the protective tube 4.
  • a transducer unit 6 acting as a level transmitter. It comprises a round, thin and flexible metal film placed in a cover part 7 and stretched by its ⁇ outer edge on a flange 9 around the cover part 7, and a transducer 10 mounted on the cover part 7.
  • the transducer contains a metal wire vibrating at a certain frequency inside a thin vertical metal tube and in it ⁇ middle a magnet unit attached to the metal tube, with a magnet inside the magnet unit.
  • a transducer like this is e.g. the P-200 measuring head designed for the measurement of structural stress, manufac ⁇ tured by Geonor A/S.
  • the transducer unit is also provided with a protective cap 11.
  • the float is subject to a buoyant force which is equal to the weight of the fuel displaced.
  • the buoyancy is transmitted via the film 8 to the force measuring transducer 10.
  • the trans- ducer 10 is further connected via a control cable 12 to a control unit, which in the case of Fig. 1 is placed in a filling automaton 13.
  • the wire in the tube starts ot vibrate in accordance with a signal received from the control unit. After a few seconds, the vibrations reach a constant amplitude and the wire continues vibrating for as long as the transducer is on.
  • the transducer 10 outputs an alternating voltage of a frequency equal to the vibration frequency, and the control unit measures the frequency of the voltage. From this frequency, the liquid level in the tank is then determined.
  • the float 5 is provided with two disconti ⁇ nuity areas 14 and 15, which are e.g. cylinders having an ex ⁇ ternal diameter somewhat larger than that of the float 5, one of which is placed at the middle of the float 5 in Fig. 1 and the other at some distance above the first one so that both are within the range of variation of the liquid level 2.
  • Both discontinuity areas 14, 15 have a constant diameter.
  • the cylinders have a length equal to about 1/10 of the height of the float 5.
  • Points of disconti ⁇ nuity A - D are thus formed at the upper and lower ends of the two cylinders, at which the external diameter of the float 5 changes in a discontinuous manner and whose heights h - h in the vertical direction (arrow 16) from the bottom (horizontal axis 17) of the tank 1 are known.
  • the disconti ⁇ nuities A - D in the diameter are used as calibration points, with the aid of which the calibration curve determined by the measuring apparatus can be adjusted in the manner described below.
  • the adjustment factor for the calibration curve -used in the measurement of liquid level can be a coefficient depending on the difference between the squares of the frequencies and on the quantity of liquid removed from the tank 1.
  • K f-f -fS
  • Fig. 2 presents an adjustment curve 21 for the tank 1 in a coordinate system in which the vertical axis represents the coefficient of adjustment K and the horizontal axis the liquid level. The starting point of the horizontal axis represents the maximum fuel level hmax and its end the minimum fuel level hmin. As can be seen from the curve, the discontinuities appear as clearly larger values than those around them. At the points of discontinuity, the derivative of the calibration curve is discontinuous.
  • the change ⁇ V in liquid vol ⁇ ume is obtained independently of the liquid level measuring apparatus as feedback data from the measuring device through which the liquid removed from the tank flows.
  • a measur ⁇ ing device can be e.g. a fuel flow meter 19 which is con ⁇ nected via a supply hose 18 to the tank 1 and from which the data is passed to the control unit of the automaton 13 via a cable 20.
  • the discontinuities on the calibration curve used in the liquid level measurement can.be accurately determined, when the liquid surface 2 has moved past them, by fitting the adjustment curve 21 with its dis ⁇ continuities h ' - h ', which are obtained e.g. from the derivative changes or from the equation presented above, so that they correspond to the real heights h - h of the dis ⁇ continuity points A - D.
  • This can be performed mathematical- ly, e.g. by the method of the least sum of squares. It is to be noted that the real heig 3 hts hA every - lvD of the discontinuities

Landscapes

  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Level Indicators Using A Float (AREA)

Abstract

Procédé et appareil d'étalonnage d'un appareil de mesure du niveau d'un liquide dans un récipient (1). L'appareil de mesure utilise un flotteur cylindrique (5) du type à flottabilité se trouvant dans le récipient (1) et ayant une hauteur au moins quasiment égale à celle du récipient (1), et une unité à transducteur (6) associée au flotteur (5) et pourvue d'une unité de commande (13). Le flotteur (5) présente au moins un point formant une solution de continuité (A-D) compris dans la zone de variation du niveau (2) du liquide, et le diamètre externe du flotteur varie en ce point. La quantité de liquide extraite du récipient (1), ou introduite dans celui-ci, est mesurée indépendamment de la mesure du niveau du liquide. L'utilisation de la mesure de cette quantité de liquide indépendante de la mesure du niveau du liquide permet de faire correspondre au moins une solution de continuité du flotteur déterminée pendant la mesure du niveau du liquide à la valeur réelle de la solution de continuité.
PCT/FI1994/000513 1993-11-16 1994-11-16 Procede et appareil d'etalonnage d'un appareil de mesure du niveau d'un liquide WO1995014217A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP95900159A EP0729564A1 (fr) 1993-11-16 1994-11-16 Procede et appareil d'etalonnage d'un appareil de mesure du niveau d'un liquide

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI935083A FI94676C (fi) 1993-11-16 1993-11-16 Menetelmä ja laitteisto nesteen mittauslaitteiston kalibroimiseksi
FI935083 1993-11-16

Publications (1)

Publication Number Publication Date
WO1995014217A1 true WO1995014217A1 (fr) 1995-05-26

Family

ID=8538964

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1994/000513 WO1995014217A1 (fr) 1993-11-16 1994-11-16 Procede et appareil d'etalonnage d'un appareil de mesure du niveau d'un liquide

Country Status (3)

Country Link
EP (1) EP0729564A1 (fr)
FI (1) FI94676C (fr)
WO (1) WO1995014217A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996038717A1 (fr) * 1995-06-02 1996-12-05 Veeder-Root Company Procede et dispositif permettant de jauger des reservoirs raccordes a des tubulures
EP1955028A1 (fr) * 2005-11-23 2008-08-13 AB Volvo Penta Procédé de calibrage de systèmes de mesure
CN105067090A (zh) * 2015-08-31 2015-11-18 中国海洋石油总公司 界面型浮球式液位计密度的修正方法
CN106289454A (zh) * 2016-08-17 2017-01-04 中国石油天然气集团公司 液位计量尺及应用其的液位计校准方法
RU2764123C1 (ru) * 2018-07-31 2022-01-13 Бюлер Аг Входное устройство для вальцового станка, вальцовый станок с таким входным устройством и способ определения уровня наполнения размалываемым материалом бункера вальцового станка

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4406152A (en) * 1981-04-27 1983-09-27 Richmond Tank Car Company Method and apparatus for calibrating a railroad tank car
US4843876A (en) * 1985-03-06 1989-07-04 Systemteknik Ab Liquid level indicator
US4914962A (en) * 1988-09-28 1990-04-10 The Slope Indicator Co. Vibrating strip transducer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4406152A (en) * 1981-04-27 1983-09-27 Richmond Tank Car Company Method and apparatus for calibrating a railroad tank car
US4843876A (en) * 1985-03-06 1989-07-04 Systemteknik Ab Liquid level indicator
US4914962A (en) * 1988-09-28 1990-04-10 The Slope Indicator Co. Vibrating strip transducer

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996038717A1 (fr) * 1995-06-02 1996-12-05 Veeder-Root Company Procede et dispositif permettant de jauger des reservoirs raccordes a des tubulures
EP1955028A1 (fr) * 2005-11-23 2008-08-13 AB Volvo Penta Procédé de calibrage de systèmes de mesure
EP1955028A4 (fr) * 2005-11-23 2010-03-03 Volvo Penta Ab Procédé de calibrage de systèmes de mesure
US8181502B2 (en) 2005-11-23 2012-05-22 Ab Volvo Penta Method of calibrating measurement systems
CN105067090A (zh) * 2015-08-31 2015-11-18 中国海洋石油总公司 界面型浮球式液位计密度的修正方法
CN106289454A (zh) * 2016-08-17 2017-01-04 中国石油天然气集团公司 液位计量尺及应用其的液位计校准方法
CN106289454B (zh) * 2016-08-17 2023-11-03 中国石油天然气集团有限公司 液位计量尺及应用其的液位计校准方法
RU2764123C1 (ru) * 2018-07-31 2022-01-13 Бюлер Аг Входное устройство для вальцового станка, вальцовый станок с таким входным устройством и способ определения уровня наполнения размалываемым материалом бункера вальцового станка
US11860020B2 (en) 2018-07-31 2024-01-02 Bühler AG Intake arrangement for a roller mill, roller mill having such an intake arrangement and method for determining the ground material fill level of a storage container of a roller mill

Also Published As

Publication number Publication date
FI94676C (fi) 1995-10-10
FI94676B (fi) 1995-06-30
FI935083A0 (fi) 1993-11-16
EP0729564A1 (fr) 1996-09-04

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