DE19755378A1 - Inductive filling level detection for cryogenic liquids working on super conducting basis - Google Patents

Inductive filling level detection for cryogenic liquids working on super conducting basis

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Publication number
DE19755378A1
DE19755378A1 DE1997155378 DE19755378A DE19755378A1 DE 19755378 A1 DE19755378 A1 DE 19755378A1 DE 1997155378 DE1997155378 DE 1997155378 DE 19755378 A DE19755378 A DE 19755378A DE 19755378 A1 DE19755378 A1 DE 19755378A1
Authority
DE
Germany
Prior art keywords
core
filling level
cryogenic liquids
level detection
coil
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
DE1997155378
Other languages
German (de)
Inventor
Horst Prof Dr Altenburg
Wieslaw Dipl Phys Jasczcuk
Helene Dr Dyck
Norbert Dipl Ing Munser
Andrej R Dr Buev
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Priority to DE1997155378 priority Critical patent/DE19755378A1/en
Publication of DE19755378A1 publication Critical patent/DE19755378A1/en
Withdrawn legal-status Critical Current

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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
    • G01F23/22—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 by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/26—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 by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C13/00—Details of vessels or of the filling or discharging of vessels
    • F17C13/02—Special adaptations of indicating, measuring, or monitoring equipment
    • F17C13/021—Special adaptations of indicating, measuring, or monitoring equipment having the height as the parameter
    • 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
    • G01F23/22—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 by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
    • F17C2223/01—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the phase
    • F17C2223/0146—Two-phase
    • F17C2223/0153—Liquefied gas, e.g. LPG, GPL
    • F17C2223/0161—Liquefied gas, e.g. LPG, GPL cryogenic, e.g. LNG, GNL, PLNG
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
    • F17C2250/04—Indicating or measuring of parameters as input values
    • F17C2250/0404—Parameters indicated or measured
    • F17C2250/0408—Level of content in the vessel

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Thermal Sciences (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electromagnetism (AREA)
  • Power Engineering (AREA)
  • Measuring Magnetic Variables (AREA)

Abstract

The filling level detector has a probe dipping in to the cryogenic liquid, and makes use of the super conducting properties of the cryogenic liquid. The probe consists of a core (1) and a coil (2), inductively coupled with the core. The measurement of the inductivity alteration of the coil and the core is used for establishing the filling level reading.

Description

Dieses Patent betrifft die Füllstandsdetektion von kryogenen Flüssigkeiten, wobei die Messung unter Ausnutzung des Effektes der Supraleitung erfolgt.This patent relates to the level detection of cryogenic liquids, the Measurement is made using the effect of superconductivity.

Bekannt ist das der Füllstand in Kryostaten mit Hilfe von supraleitenden Drähten, die in die Flüssigkeit eingetaucht werden, gemessen werden kann. Es bleibt dann der Teil des Drahtes, der sich oberhalb der Oberfläche der kryogenen Flüssigkeit befindet, im normal­ leitenden Zustand und der in die Flüssigkeit eingetauchte Teil geht in den supraleitenden Zustand über. Bei einem aufgeschaltetem Konstantstrom läßt sich durch die Messung des Spannungsabfalles feststellen wie groß der Anteil des normalleitenden Widerstandes (entspricht dem nichteingetauchten Teil der Sonde) bezogen auf den Gesamtwiderstand ist. Aus diesem Wert läßt sich dann auf das Niveau der kryogenen Flüssigkeit schließen. Bis zur Entwicklung der supraleitenden Keramiken war diese Meßmethode auf flüssiges Helium beschränkt, und man mußte bei der Füllstandsdetektion von anderen Flüssig­ keiten wie z. B. Stickstoff auf andere Methoden zurückgreifen. Hier bediente man sich vorwiegend der kapazitiven Methode, oder eines Verfahrens unter Verwendung von Kohle- oder Halbleiterwiderständen. Bei der kapazitiven Methode wird der Umstand genutzt, daß sich die Kapazität eines Kondensators ändert, wenn sich flüssiger Stickstoff anstelle gasförmigen zwischen den Kondensatorplatten befindet.It is known that the level in cryostats with the help of superconducting wires that are in the liquid can be immersed, can be measured. It remains the part of the Wire that is above the surface of the cryogenic liquid is normal conductive state and the part immersed in the liquid goes into the superconducting Condition about. With a constant current applied, the measurement of Voltage drop determine how large the proportion of the normal conducting resistance (corresponds to the non-immersed part of the probe) related to the total resistance is. The level of the cryogenic liquid can then be inferred from this value. Until the development of superconducting ceramics, this measuring method was based on liquid Helium limited, and you had to use liquid to detect the level of other such as B. nitrogen using other methods. Here one used predominantly the capacitive method, or a method using Carbon or semiconductor resistors. With the capacitive method, the fact used that the capacity of a capacitor changes when liquid nitrogen instead of gaseous between the capacitor plates.

Diese Meßmethode ist jedoch aufgrund der Eisbildung an den Kondensatorplatten sehr störanfällig. Beiden Meßgräten auf Basis von Kohle- oder Halbleiterwiderständen wird die Tatsache ausgenutzt, daß diese Materialien ihren Widerstand mit abnehmender Temperatur erhöhen. Diese Widerstandszunahme ist bei Kohlewiderständen sehr klein und linear; bei Halbleitern steigt der Widerstand exponentiell. Da beide bei der für Stickstoff wichtigen Temperatur von 77 K keine markante Widerstandsänderung aufweisen, muß der Absolut­ wert des Sensorwiderstandes durch aufwendige Eichvorgänge genauestens bestimmt werden. Außerdem müssen die bei diesen Verfahren- auftretenden, zeitlichen Schwankungen der Widerstandsverlaufes durch häufiges regelmäßiges Eichen kompensiert werden.However, this measurement method is very much due to the ice formation on the capacitor plates prone to failure. Both measuring devices based on carbon or semiconductor resistances will Taking advantage of the fact that these materials increase their resistance with decreasing temperature increase. This increase in resistance is very small and linear with coal resistors; at Resistance increases exponentially in semiconductors. Because both are important for nitrogen Temperature of 77 K have no significant change in resistance, the absolute value of the sensor resistance precisely determined by complex calibration processes become. In addition, the time that occurs in these processes Fluctuations in the course of resistance are compensated for by regular regular calibration become.

Die hier vorgestellte Erfindung geht von der Aufgabe aus, eine Meßsonde zu entwickeln, die sich zum einen mit einem vertretbaren Aufwand herstellen läßt, genügend langzeitstabil ist, und zum anderen sollte das das Konzept einer solchen Sonde so universell ausgearbeitet sein, daß es sich gleichermaßen für kontinuierliche als auch diskrete Messungen eignet, und durch die Wahl von geeigneten supraleitenden Materialien auf die für verschiedene kryogene Flüssigkeiten spezifische Temperatur abgestimmt werden kann.The invention presented here is based on the task of developing a measuring probe which, on the one hand, can be manufactured with reasonable effort, is sufficiently long-term stable and on the other hand, the concept of such a probe should be worked out so universally be suitable for continuous as well as discrete measurements, and through the selection of suitable superconducting materials for those for different cryogenic liquids specific temperature can be tuned.

Der hauptsächliche Vorteil dieses neuen Füllstandsdetektierungssystem liegt in der hohen Meßgenauigkeit, der Langzeitstabilität, der Reproduzierbarkeit der Meßwerte auch bei sehr großen Sonden sowie im Verzicht auf Kontaktierung des Supraleiters mit anderen Materialien. The main advantage of this new level detection system is its high level Measurement accuracy, long-term stability, the reproducibility of the measured values very large probes and without contacting the superconductor with others Materials.  

Die Theorie einer solchen Detektors ist im folgenden beschrieben:The theory of such a detector is described below:

Während bei den bisher angebotenen Systemen die Füllstandsdektierung ausschließlich auf der Widerstandsänderung beruhen, nutzen wir bei dieser Meßmethode die magnetischen Eigen­ schaften (Änderung der Permeabilität) des supraleitenden Materials aus. Die Widerstands­ änderung von supraleitendem Material, welche mit der Permeabilitätsänderung des Materials einhergeht, kann auch einfach durch die Erfassung der Induktivitätsänderung einer, an das supraleitende Material gekoppelten Spule, aufgenommen werden.While in the systems offered so far, the level detection exclusively on the Change in resistance, we use the magnetic eigen with this measurement method properties (change in permeability) of the superconducting material. The resistance Change in superconducting material, which changes with the change in permeability of the material goes hand in hand, simply by detecting the change in inductance one to which superconducting material coupled coil.

Wenn ein solches Meßsystem komplett im normalleitenden Zustand ist, besitzt es die maximale Induktivität Lmax, wenn es komplett im supraleitenden Zustand ist, die minimale Induktivität Lmin. Davon ausgehend, daß die Gesamtinduktivität eines solchen Sensors proportional zu seiner Länge ist, kann man aus der Beziehung ΔL = Lmax - Lmin auf das Flüssigkeitnivau schließen. Siehe auch Abb. 1: PrinzipschaltbildIf such a measuring system is completely in the normally conductive state, it has the maximum inductance L max , if it is completely in the superconducting state, the minimum inductance L min . Assuming that the total inductance of such a sensor is proportional to its length, one can infer the liquid level from the relationship ΔL = L max - L min . See also Fig. 1: Block diagram

Für die Induklivität gilt folgende Beziehung:
The following relationship applies to inductivity:

L = µµ0AN2I-1
µ0[Hm-1] = 4π10-7
µ = 1 + χ
A[m2] = Querschnitt der Spule
l[m] = Länge der Spule
N = Anzahl der Windungen L = µµ 0 AN 2 I -1
µ 0 [Hm -1 ] = 4π10 -7
µ = 1 + χ
A [m 2 ] = cross section of the coil
l [m] = length of the coil
N = number of turns

1. SL-Kern1. SL core

Für dieses Meßprinzip spielt die Ausführung des SL-Kerns nur eine zweitrangige Rolle. Er kann aus einer relativ lockeren Pulverschüttung bestehen, aus gesintertem Granulat oder auch aus Massivmaterialien wie Tabletten, Ringen u.s.w.The execution of the SL core plays only a secondary role for this measuring principle Role. It can consist of a relatively loose powder bed, sintered Granules or from solid materials such as tablets, rings, etc.

2. Einbettungselement2. Embedding element

Das Einbettungselement besteht für lose Materialien wie Pulver und Granulat sowie für Tabletten aus einem Rohr aus speziellen Kryomaterial ohne elektrische und magnetische Leitfähigkeit.The embedding element is made for loose materials such as powder and granules as well for tablets from a tube made of special cryogenic material without electrical and magnetic conductivity.

3. Spule (Induktivität3rd coil (inductance

Als Spule wirkt hier eine an Anzahl von, aus Wicklungsdraht bestehenden, Wicklungen die direkt auf das Einbettrohr aufgebracht wurde.A number of windings consisting of winding wire acts as a coil here which was applied directly to the embedding tube.

4. Schutzgehäuse4. Protective housing

Das Schutzgehäuse dient neben dem mechanischen Schutz beim Einbau und Befüllen auch zur Vereinfachung der HandhabungThe protective housing is used in addition to the mechanical protection during installation and filling also to simplify handling

5. L-Meter5. L-meter

Die Messung der Induktivitätsänderung erfolgt mit einem laborüblichen Vielfach­ meßgerät.The change in inductance is measured using a laboratory-standard multiple measuring device.

Claims (4)

1. Füllstandsdetektor für kryogene Flüssigkeiten, zur Detektierung des Flüssigkeitsstandes mit Hilfe einer auf Supraleitung Basis arbeitender, in die kryogene Flüssigkeit einzutauchende Sonde, die dadurch gekennzeichnet ist, daß die Sonde aus einem Kern (1) und einer mit dem Kern induktiv gekoppelten Spule (2) besteht.1. Level detector for cryogenic liquids, for detecting the liquid level with the aid of a superconducting-based probe that is immersed in the cryogenic liquid, which is characterized in that the probe consists of a core ( 1 ) and a coil ( 2 ) consists. 2. Füllstandsdetektor nach Anspruch (1), dadurch gekennzeichnet, daß er die Messung der Induktivitätsänderung der Spule und des Kerns zur Feststellung des Füllstandes ausnutzt.2. Level detector according to claim (1), characterized in that it measures the Exploitation of the inductance of the coil and the core is used to determine the fill level. 3. Füllstandsdetektor nach Anspruch (1), dadurch gekennzeichnet, daß der für den Kern ausgewählte Stoff eine temperaturabhängige magnetische Permeabilität besitzt.3. Level detector according to claim (1), characterized in that for the core selected substance has a temperature-dependent magnetic permeability. 4. Füllstandsdetektor nach Anspruch (1), dadurch gekennzeichnet, daß für konkrete kryogene Flüssigkeiten in den entsprechenden Temperaturbereichen um den Siedepunkt der jeweiligen Flüssigkeit, ein Stoff als Kern benutzt wird, der in diesem Temperaturbereich seine maximale Abhängigkeit der Permeabilität besitzt.4. Level detector according to claim (1), characterized in that for specific cryogenic Liquids in the corresponding temperature ranges around the boiling point of the respective Liquid, a substance used as the core, which is at its maximum in this temperature range Dependency of permeability.
DE1997155378 1997-12-12 1997-12-12 Inductive filling level detection for cryogenic liquids working on super conducting basis Withdrawn DE19755378A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE1997155378 DE19755378A1 (en) 1997-12-12 1997-12-12 Inductive filling level detection for cryogenic liquids working on super conducting basis

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1997155378 DE19755378A1 (en) 1997-12-12 1997-12-12 Inductive filling level detection for cryogenic liquids working on super conducting basis

Publications (1)

Publication Number Publication Date
DE19755378A1 true DE19755378A1 (en) 1999-06-17

Family

ID=7851754

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DE1997155378 Withdrawn DE19755378A1 (en) 1997-12-12 1997-12-12 Inductive filling level detection for cryogenic liquids working on super conducting basis

Country Status (1)

Country Link
DE (1) DE19755378A1 (en)

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