EP0212567A2 - Device for regulating the fuel and oxidant gas supply for a burner of an atomic absorption spectrometer - Google Patents

Device for regulating the fuel and oxidant gas supply for a burner of an atomic absorption spectrometer Download PDF

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Publication number
EP0212567A2
EP0212567A2 EP86111215A EP86111215A EP0212567A2 EP 0212567 A2 EP0212567 A2 EP 0212567A2 EP 86111215 A EP86111215 A EP 86111215A EP 86111215 A EP86111215 A EP 86111215A EP 0212567 A2 EP0212567 A2 EP 0212567A2
Authority
EP
European Patent Office
Prior art keywords
turbine wheel
gas
oxidant
fuel gas
control unit
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.)
Granted
Application number
EP86111215A
Other languages
German (de)
French (fr)
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EP0212567A3 (en
EP0212567B1 (en
Inventor
Bernhard Huber
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PE Manufacturing GmbH
Original Assignee
Bodenseewerk Perkin Elmer and Co GmbH
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Publication of EP0212567A2 publication Critical patent/EP0212567A2/en
Publication of EP0212567A3 publication Critical patent/EP0212567A3/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/10—Mixing gases with gases
    • B01F23/19—Mixing systems, i.e. flow charts or diagrams; Arrangements, e.g. comprising controlling means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N1/00—Regulating fuel supply
    • F23N1/02—Regulating fuel supply conjointly with air supply
    • F23N1/022—Regulating fuel supply conjointly with air supply using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N1/00—Regulating fuel supply
    • F23N1/02—Regulating fuel supply conjointly with air supply
    • F23N1/025—Regulating fuel supply conjointly with air supply using electrical or electromechanical means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00—Measuring
    • F23N2225/02—Measuring filling height in burners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2241/00—Applications
    • F23N2241/16—Spectrometer burners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/2496—Self-proportioning or correlating systems
    • Y10T137/2514—Self-proportioning flow systems
    • Y10T137/2521—Flow comparison or differential response
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/2496—Self-proportioning or correlating systems
    • Y10T137/2514—Self-proportioning flow systems
    • Y10T137/2521—Flow comparison or differential response
    • Y10T137/2529—With electrical controller
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/2496—Self-proportioning or correlating systems
    • Y10T137/2559—Self-controlled branched flow systems
    • Y10T137/2564—Plural inflows
    • Y10T137/2567—Alternate or successive inflows
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/7722—Line condition change responsive valves
    • Y10T137/7781—With separate connected fluid reactor surface
    • Y10T137/7793—With opening bias [e.g., pressure regulator]
    • Y10T137/7822—Reactor surface closes chamber
    • Y10T137/7823—Valve head in inlet chamber
    • Y10T137/7825—Rectilinear valve stem rigid with reactor surface

Definitions

  • a line-emitting light source emits a light bundle that contains the resonance spectral lines of a sought element.
  • This beam of light passes through a flame burning on a burner and falls on a photoelectric detector.
  • a liquid sample to be examined is sprayed into the flame by means of an atomizer, so that the sample is atomized by the flame and the elements contained in the sample are present in the flame in atomic form.
  • the then weakening of the light beam in the flame provides a measure of the proportion of the element sought in the sample.
  • the burner is fired with a fuel gas, e.g. Acetylene, and air operated as an oxidant.
  • nitrous oxide N 2 O
  • Nitrous oxide has a higher oxygen content than air.
  • the supply of fuel gas is increased in order to maintain the correct stoichiometric ratio between fuel gas and oxidant.
  • the gas control device mentioned at the outset is provided, which ensures the setting of the gas flows to the burner and the keeping of these gas flows constant.
  • a fixed throttle is provided and the pressure is changed to adjust the gas flow.
  • the flow of the fuel gas when switching to a second oxidant with a higher oxygen content, for example laughing gas can be increased in a defined manner via the servomotor and the setpoint of the pressure regulator.
  • DE-OS 28 33 553 discloses a gas control device for controlling the supply of fuel gas to a burner in an atomic absorption spectrometer, in which a digital value supplied by a control unit is converted into an electrical voltage by a D / A converter. This voltage is applied to a voltage-pressure converter, which converts it into a proportional pressure. The voltage-pressure converter in turn acts on a “volume booster” (not described in more detail) which is arranged in the fuel gas line downstream of a fixed pressure regulator. There is no flow measurement and feedback there.
  • DE-OS 30 05 784 shows a gas control device for controlling the fuel gas and oxidant supply to a burner in an atomic absorption spectrometer, in which the pressure of the oxidant is regulated by a fixed pressure regulator and the pressure regulator is followed by a flow regulator.
  • This flow regulator contains a fixed throttle and a needle valve downstream of it. The pressure drop across the fixed throttle is converted into an electrical signal by means of a differential pressure converter. Depending on this signal, the needle valve can be adjusted, possibly automatically via a servomotor.
  • a corresponding flow regulator is provided for the fuel gas.
  • DE-OS 25 52 890 shows a turbine wheel flow meter with a turbine wheel which carries at least one magnet which excites a magnetic field probe for generating output pulses with each revolution of the rotor.
  • the magnetic field probe contains a Hall sensor.
  • the invention has for its object to design a gas control device of the type mentioned with simple and inexpensive means so that the gas flows can be adjusted reproducibly.
  • the pressure regulator is set to such a pressure that the desired gas flow reproducibly flows through the fixed throttle.
  • a turbine wheel flow meter is used as a measuring device for the flow velocity, which gives direct digital signals to the control unit. It is not a variable throttle in the form of a - complex - needle valve adjusted but the setpoint of a pressure regulator arranged upstream of a fixed throttle. Compared to DE-OS 30 05 784, very complex electronic components in the form of the differential pressure converter and an A / D converter connected downstream of it are avoided.
  • the construction according to the invention thus creates a device which is inexpensive in comparison with previously known gas control devices and which nonetheless permits a reproducible setting of predetermined flow rates.
  • the gas control device contains a first connection 10, to which a first oxidant in the form of compressed air can be connected, a second connection 12, which can be connected to a source of laughing gas as the second oxidant.
  • a third connection 14 can be connected to a source of fuel gas, preferably acetylene.
  • a pressure sensor 16, 18 and 20 is connected to each of the three connections 10, 12 and 14. The pressure sensors 16, 18, 20 signal whether gas pressure is present at the connection in question. These signals are connected to a control unit 28 via signal lines 22, 24 or 26.
  • the control unit 28 is a microprocessor-controlled electronics according to the main patent bib (patent application P 34 07 552.6).
  • the first connection 10 is followed by a shut-off valve 30 designed as a solenoid valve, which is controlled by the control unit 28 via a control line 32 and is shut off in the de-energized state.
  • a shut-off valve 30 designed as a solenoid valve, which is controlled by the control unit 28 via a control line 32 and is shut off in the de-energized state.
  • a 3/2-way valve 34 is designed as a solenoid valve and is also controlled by the control unit 28 via a control line 36.
  • the 2/3 directional valve 34 connects the first connection 10 and the shut-off valve 30 connected downstream thereof to a line 38, while the second connection 12 is closed.
  • the 3/2-way valve 34 Connects in its second switching position the 3/2-way valve 34 the second port 12 with the line 38, while the connection to the shut-off valve 30 and the first port 10 is shut off.
  • the 3/2-way valve In the de-energized state, the 3/2-way valve is in its first switching position, which is shown in Fig. 1.
  • Von.der 38 leads a branch line 39 via a pressure regulator 37 to an atomizer.
  • a storage volume 41 is connected between the shut-off valve 30 and the 3/2-way valve 34.
  • the line 38 leads to a pressure regulator 40.
  • the output of the pressure regulator 40 is connected via a fixed throttle 44 to an oxidant connection of the burner.
  • the pressure regulator 40 is a conventional pressure reducing valve, the setpoint of which can be changed via an adjusting spindle.
  • the adjusting spindle can be adjusted by an actuator 46.
  • the servomotor 46 or suitable tapping means give position signals to the control unit 28.
  • the servomotor 46 is accordingly controlled by the control unit 28. This is represented by a line 48.
  • the third connection 14 is followed by a shut-off valve 50 designed as a solenoid valve.
  • the shut-off valve is controlled by the control unit 28 via a line 52.
  • the third connection 14 is connected to a pressure regulator 54 via the shut-off valve 50.
  • the pressure regulator 54 is also a conventional pressure reducing valve like the pressure regulator 40.
  • An adjusting spindle of the pressure regulator 54 for adjusting the setpoint is adjustable by means of a servomotor 56.
  • the servomotor 56 or suitable tapping means give position signals to the control unit 28.
  • the servomotor 56 is accordingly controlled by the control unit 28.
  • the exit of the Pressure regulator 54 is connected to a fuel gas connection of the burner via a fixed throttle 58.
  • the pressure regulator 37 in the branch line 39 is followed by a flow meter 43 via a throttle 37, the signal line 43 'of which is connected to the control unit 28.
  • a flow meter 45 whose signal line 45 ′ is connected to the control unit 28, is connected downstream of the pressure regulator 40 via the throttle 44.
  • a flow meter 59 whose signal line 59 'is connected to the control unit 28, is connected downstream of the pressure regulator 54 via throttle 58.
  • Each flow meter 43, 45, 59 is constructed in the manner shown in FIGS. 2a, b.
  • a turbine wheel 49 with vanes 51 is rotatably mounted in bearings 53 in a housing 47 which is closed on all sides.
  • a gas inlet 55 is designed like a nozzle and is oriented tangentially to the vanes 51 of the turbine wheel 49.
  • a gas outlet 57 of the housing 47 is connected to the line leading to the atomizer, the oxidant connection or the fuel gas connection of the burner.
  • Each flow meter 43, 45, 49 contains means for interacting with the turbine wheel 49 for generating signals for indicating the gas flow.
  • the turbine wheel 49 is provided with two diametrically opposite magnets 61 which can be embedded, for example, in the plastic from which the turbine wheel 49 is made.
  • a Hall sensor 63 is arranged in the housing 47 in the area of action of the magnets 61. which is connected to the respective signal line 43 ', 45' or 59 '.
  • an output signal is generated at the Hall sensor 63 when one of the magnets 61 arranged on the turbine wheel 49 passes the Hall sensor 63.
  • the frequency of these output signals is dependent on the rotational speed of the turbine wheel 49 and thus on the flow speed of the gas that strikes the turbine wheel 49 through the gas inlet 55.
  • the occurrence of these output signals can be used in various ways to determine the flow velocity of the gas. For example, the time between the occurrence of two successive output signals can be determined.
  • K and m parameters that are determined empirically for the different arrangements. The value of these parameters depends, for example, on the structure of the gas inlet 55 in the housing 47, on the structure of the housing 47 and on the shape of the turbine wheel 49. These parameters, especially K, are also dependent on the type and composition of the gas flowing through the housing 47 and that Turbine wheel 49 drives. However, the parameters can be determined with high accuracy for each arrangement and each gas, so that the gas flows of the specified type can be measured with great accuracy and reproducibly adjusted via the control unit 28 and the pressure regulator 37, 40, 54.
  • magnets 61 and the Hall sensor 63 which represent particularly simple and easy-to-implement signal-generating means
  • other, preferably non-contact, signal-generating means can also be used, which enable the rotational speed of the turbine wheel 47 to be determined.
  • the output signals of the Hall sensors 63 input into the control unit 28 are processed in the control unit 28, i.e. for certain circumstances, e.g. Air or nitrous oxide compared as an oxidant, stored or specified target values.
  • the respective controllers 37, 40, 54 are adjusted via the associated servomotors 37 ', 46 and 56.
  • the program steps required for this can easily be incorporated into the programming of the control unit 28 and do not require any further explanation at this point.
  • FIG. 3 An advantageous arrangement of the flow meters is shown schematically in FIG. 3.
  • the housings 47 of the three flow meters 43, 45 and 59 are arranged together to form a block 69 which is directly connected to the pressure regulators 37, 40, and 54.
  • the gas inlets 55 of the individual housings 47 in the block 69 are formed by flow restrictors in the manner of the flow restrictors 44 and 58.
  • the gas outlets 57 are arranged, to which the lines to the atomizer, the oxidant connection and the fuel gas connection of the burner are connected directly.
  • the housing 47 as a whole or its parts in the region of the turbine wheel 49 can consist of a non-magnetic metal.
  • the turbine wheel 49 is braked by eddy currents which are caused by the rotation of the turbine wheel. This has the advantage that the service life of the device is increased and the frequency of the signals generated by the Hall sensor 63 is kept low, which increases the measuring accuracy.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Measuring Volume Flow (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Feeding And Controlling Fuel (AREA)
  • Control Of Fluid Pressure (AREA)
  • Regulation And Control Of Combustion (AREA)
  • Flow Control (AREA)

Abstract

Die Gasregeleinrichtung enthält in den Zuleitungen zum Zerstäuber, Oxidansanschluß und Brenngasanschluß des Brenners je einen Druckregler (35,40,54) und je einen, dem Druckregler nachgeschalteten Strömungsmesser (43,45,59). Die Strömungsmesser enthalten ein Turbinenrad (49), das von dem durchströmenden Gas beaufschlagt ist und durch dessen Drehung von der Drehgeschwindigkeit und damit von der Gasströmung abhängige Ausgangssignale erzeugt werden. Diese Ausgangssignale werden in die Steuereinheit (28) eingegeben, und die Stellmotore (37',46,56) der Druckregler (37,40,54) werden reproduzierbar auf bestimmte Gasströmungen eingestellt.The gas control device contains a pressure regulator (35, 40, 54) and one flow meter (43, 45, 59) downstream of the pressure regulator in the feed lines to the atomizer, oxidant connection and fuel gas connection of the burner. The flow meters contain a turbine wheel (49) which is acted upon by the gas flowing through and whose rotation produces output signals which are dependent on the rotational speed and thus on the gas flow. These output signals are input into the control unit (28) and the servomotors (37 ', 46, 56) of the pressure regulators (37, 40, 54) are reproducibly adjusted to certain gas flows.

Description

Die Erfindung betrifft eine Gasregeleinrichtung zur Regelung der Brenngas- und Oxidanszufuhr zu einem Brenner bei einem Atomabsorptions-Spektrometer, ent­haltend

  • (a) je eine Drossel für Brenngas und Oxidans und
  • (b) je einen der Drossel vorgeschalteten Druck­regler für Brenngas und Oxidans,
bei welcher
  • (c) die Drosseln für Brenngas und Oxidans feste Durchflußquerschnitte haben,
  • (d) die Sollwerte der Druckregler durch je einen Stellmotor reproduzierbar einstellbar sind und
  • (e) eine Steuereinheit mit einer mikroprozessorge­steuerten Elektronik vorgesehen ist, durch welche die Stellmotore in reproduzierbarer Weise steuerbar sind.
The invention relates to a gas control device for controlling the supply of fuel gas and oxidants to a burner in an atomic absorption spectrometer, comprising
  • (a) a throttle for fuel gas and oxidant and
  • (b) a pressure regulator for fuel gas and oxidant upstream of the throttle,
in which
  • (c) the throttles for fuel gas and oxidant have fixed flow cross sections,
  • (d) the setpoints of the pressure regulators are reproducibly adjustable by means of one servomotor each and
  • (e) a control unit with microprocessor-controlled electronics is provided, by means of which the servomotors can be controlled in a reproducible manner.

Bei einem Atomabsorptions-Spektrometer sendet eine linienemittierende Lichtquelle ein Lichtbündel aus, das die Resonanzspektrallinien eines gesuchten Elements enthält. Dieses Lichtbündel durchsetzt eine auf einem Brenner brennende Flamme und fällt auf einen photoelektrischen Detektor. In die Flamme wird mittels eines Zerstäubers eine zu untersuchen­de flüssige Probe eingesprüht, so daß die Probe durch die Flamme atomisiert wird und die in der Probe enthaltenen Elemente in der Flamme in ato­marer Form vorliegen. Die dann auftretende Schwächung des Lichtbündels in der Flamme liefert ein Maß für den Anteil des gesuchten Elements in der Probe. Der Brenner wird dabei mit einem Brenn­gas, z.B. Azetylen, und Luft als Oxidans betrieben. Es ist auch bekannt, dem Brenner statt Luft Lachgas (N ₂ O) als Oxidans zuzuführen, um eine heißere Flamme zu erhalten. Lachgas hat einen höheren Sauerstoffanteil als Luft. Bei Verwendung von Lach­gas wird die Zufuhr von Brenngas erhöht, um das richtige stöchiometrische Verhältnis zwischen Brenngas und Oxidans einzuhalten.In an atomic absorption spectrometer, a line-emitting light source emits a light bundle that contains the resonance spectral lines of a sought element. This beam of light passes through a flame burning on a burner and falls on a photoelectric detector. A liquid sample to be examined is sprayed into the flame by means of an atomizer, so that the sample is atomized by the flame and the elements contained in the sample are present in the flame in atomic form. The then weakening of the light beam in the flame provides a measure of the proportion of the element sought in the sample. The burner is fired with a fuel gas, e.g. Acetylene, and air operated as an oxidant. It is also known to supply the burner with nitrous oxide (N ₂ O) as an oxidant in order to obtain a hotter flame. Nitrous oxide has a higher oxygen content than air. When using nitrous oxide, the supply of fuel gas is increased in order to maintain the correct stoichiometric ratio between fuel gas and oxidant.

Um reproduzierbare Verhältnisse zu erhalten, ist die eingangs erwähnte Gasregeleinrichtung vorge­sehen, welche die Einstellung der Gasströmungen zum Brenner und die Konstanthaltung dieser Gasströmun­gen gewährleistet. Bei dieser Gasregeleinrichtung ist eine fest eingestellte Drossel vorgesehen und zur Einstellung der Gasströmung wird der Druck verändert. Insbesondere kann so die Strömung des Brenngases bei der Umschaltung auf ein zweites Oxidans mit höherem Sauerstoffanteil, z.B. Lachgas, über den Stellmotor und den Sollwert des Druckreg­lers in definierter Weise erhöht werden.In order to obtain reproducible conditions, the gas control device mentioned at the outset is provided, which ensures the setting of the gas flows to the burner and the keeping of these gas flows constant. In this gas control device, a fixed throttle is provided and the pressure is changed to adjust the gas flow. In particular, the flow of the fuel gas when switching to a second oxidant with a higher oxygen content, for example laughing gas, can be increased in a defined manner via the servomotor and the setpoint of the pressure regulator.

Es hat sich gezeigt, daß eine solche Gasregelein­richtung zwar optimal steuerbar ist, aber eine bestimmte Einstellung bei einer Verstellung der Zerstäuberdüse oder einer Änderung des Vordrucks nicht leicht reproduziert werden kann.It has been shown that such a gas control device can be optimally controlled, but a certain setting cannot be easily reproduced when the atomizing nozzle is adjusted or the admission pressure changes.

Durch die DE-OS 28 33 553 ist eine Gasregelein­richtung zur Regelung der Brenngaszufuhr zu einem Brenner bei einem Atomabsorptions-Spektrometer bekannt, bei welcher ein von einem Steuergerät gelieferter Digitalwert von einem D/A-Wandler in eine elektrische Spannung umgesetzt wird. Diese Spannung wird auf einen Spannungs-Druck-Wandler gegeben und von diesem in einen proportionalen Druck umgesetzt. Der Spannungs-Druck-Wandler beaufschlagt wiederum einen nicht näher beschrie­benen "Volumenbooster", der in der Brenngasleitung stromab von einem fest eingestellten Druckregler angeordnet ist. Eine Strömungsmessung und Rückfüh­rung erfolgt dort nicht.DE-OS 28 33 553 discloses a gas control device for controlling the supply of fuel gas to a burner in an atomic absorption spectrometer, in which a digital value supplied by a control unit is converted into an electrical voltage by a D / A converter. This voltage is applied to a voltage-pressure converter, which converts it into a proportional pressure. The voltage-pressure converter in turn acts on a “volume booster” (not described in more detail) which is arranged in the fuel gas line downstream of a fixed pressure regulator. There is no flow measurement and feedback there.

Die DE-OS 30 05 784 zeigt eine Gasregeleinrichtung zur Regelung der Brenngas- und Oxidanszufuhr zu einem Brenner bei einem Atomabsorptions-Spektro­meter, bei welcher der Druck des Oxidans durch einen fest eingestellten Druckregler geregelt wird und dem Druckregler ein Strömungsregler nachge­schaltet ist. Dieser Strömungsregler enthält eine feste Drossel und stromab von dieser ein Nadelven­til. Der Druckabfall an der festen Drossel wird mittels eines Differenzdruckwandlers in ein elektrisches Signal umgesetzt. In Abhängigkeit von diesem Signal ist das Nadelventil, ggf. automatisch über einen Stellmotor, verstellbar. Ein ent­sprechender Strömungsregler ist für das Brenngas vorgesehen.DE-OS 30 05 784 shows a gas control device for controlling the fuel gas and oxidant supply to a burner in an atomic absorption spectrometer, in which the pressure of the oxidant is regulated by a fixed pressure regulator and the pressure regulator is followed by a flow regulator. This flow regulator contains a fixed throttle and a needle valve downstream of it. The pressure drop across the fixed throttle is converted into an electrical signal by means of a differential pressure converter. Depending on this signal, the needle valve can be adjusted, possibly automatically via a servomotor. A corresponding flow regulator is provided for the fuel gas.

Die Firmendruckschrift der Firma Carl Zeiss, Ober­kochen/Württ. "Flammenzusatz zum Spektralphotometer PMQ II und Registrierenden Spektralphotometer RPQ 20A" zeigt eine Gasregelvorrichtung mit Fein­druckreglern für Brenngas und Oxidans und einer auswechselbaren Drosseldüse in der Brenngasleitung.The company brochure of the company Carl Zeiss, Oberkochen / Württ. "Flame additive to the PMQ II spectrophotometer and RPQ 20A registration spectrophotometer" shows a gas control device with fine pressure regulators for fuel gas and oxidant and a replaceable throttle nozzle in the fuel gas line.

Die DE-OS 25 52 890 zeigt einen Turbinenrad-Strö­mungsmesser mit einem Turbinenrad, das mindestens einen Magneten trägt, der bei jeder Umdrehung des Rotors eine Magnetfeldsonde zur Erzeugung von Aus­gangsimpulsen erregt. Die Magnetfeldsonde enthält einen Hall-Sensor.DE-OS 25 52 890 shows a turbine wheel flow meter with a turbine wheel which carries at least one magnet which excites a magnetic field probe for generating output pulses with each revolution of the rotor. The magnetic field probe contains a Hall sensor.

Der Erfindung liegt die Aufgabe zugrunde, eine Gasregelvorrichtung der eingangs genannten Art mit einfachen und preisgüngstigen Mitteln so auszubilden, daß sich die Gasströmungen reproduzierbar einstellen lassen.The invention has for its object to design a gas control device of the type mentioned with simple and inexpensive means so that the gas flows can be adjusted reproducibly.

Erfindungsgemäß wird diese Aufgabe dadurch gelöst, daß

  • (f) jedem Druckregler ein Turbinenrad-Strömungs­messer nachgeschaltet ist,
  • (g) an dem Turbinenrad-Strömungsmesser signaler­zeugende Mittel vorgesehen sind, die mit dem Turbinenrad zur Erzeugung von Ausgangsimpulsen zusammenwirken, deren Frequenz der Drehzahl des Turbinenrades proportional ist,
  • (h) die Ausgangsimpulse auf die Steuereinheit zur Bildung eines digitalen Strömungsgeschwindig­keitssignals aufgeschaltet sind und
  • (i) die Sollwerte der Druckregler über die von der Steuereinheit ansteuerbaren Stellmotore im Sinne der Einhaltung vorgegebener Strömungs­geschwindigkeits-Sollwerte veränderbar sind.
According to the invention, this object is achieved in that
  • (f) a turbine wheel flow meter is connected downstream of each pressure regulator,
  • (g) signal-generating means are provided on the turbine wheel flow meter, which cooperate with the turbine wheel to generate output pulses, the frequency of which is proportional to the rotational speed of the turbine wheel,
  • (h) the output pulses are applied to the control unit to form a digital flow rate signal and
  • (i) the setpoints of the pressure regulators can be changed by means of the servomotors which can be controlled by the control unit in order to maintain specified flow velocity setpoints.

Auf diese Weise erfolgt eine Rückmeldung über die tatächliche Gasströmung an die Steuereinheit. Der Druckregler wird jeweils auf einen solchen Druck eingestellt, daß durch die feste Drossel reprodu­zierbar die gewünschte Gasströmung fließt.In this way, the actual gas flow is reported back to the control unit. The pressure regulator is set to such a pressure that the desired gas flow reproducibly flows through the fixed throttle.

Damit wird die gewünschte Reproduzierbarkeit in der Einstellung der Gasströmungen für alle Betriebsbe­dingungen der Gasregeleinrichtung erreicht und zwar unabhängig von z.B. Neujustierungen des Zerstäubers und Änderungen des an dem Druckregler anliegenden Vordrucks.This achieves the desired reproducibility in the setting of the gas flows for all operating conditions of the gas control device, regardless of e.g. Readjustments of the atomizer and changes to the upstream pressure on the pressure regulator.

Im Gegensatz zu der DE-OS 28 33 553 erfolgt bei der erfindungsgemäßen Anordnung eine Strömungsmessung und eine Rückführung des Strömungsmeßwertes zu einem Steuergerät. Ebenfalls im Gegensatz zu der DE-OS 28 33 553 wird die Strömung
dadurch geregelt, daß der Sollwert eines vor einer festen Drossel angeordneten Druckreglers veränderbar ist. Diese Veränderung des Sollwertes des Druckreglers erfolgt in Abhängigkeit von dem rückgeführten Strömungsmeßwert. Aufwendige D/A-Wandler, Spannungs-Druck-Wandler und Volumen­booster sind entbehrlich.In contrast to DE-OS 28 33 553, a flow measurement and a return of the flow measurement value to a control unit takes place in the arrangement according to the invention. Also in contrast to DE-OS 28 33 553, the flow
regulated in that the setpoint of a pressure regulator arranged in front of a fixed throttle can be changed. This change in the setpoint of the pressure regulator takes place as a function of the returned measured flow value. Elaborate D / A converters, voltage-pressure converters and volume boosters are unnecessary.

Im Gegensatz zu der DE-OS 30 05 784 wird als Meßgeber für die Strömungsgeschwindigkeit ein Turbinenrad-Strömungsmesser benutzt, der unmittel­bar digitale Signale an die Steuereinheit gibt. Es wird nicht eine variable Drossel in Form eines - aufwendigen - Nadelventils verstellt sondern der Sollwert eines stromauf von einer festen Drossel angeordneten Druckreglers. Auch im Vergleich zu der DE-OS 30 05 784 werden sehr aufwendige elektro­nische Bauteile in Form des Differenzdruckwandlers und eines diesem nachgeschalteten A/D-Wandlers vermieden.In contrast to DE-OS 30 05 784, a turbine wheel flow meter is used as a measuring device for the flow velocity, which gives direct digital signals to the control unit. It is not a variable throttle in the form of a - complex - needle valve adjusted but the setpoint of a pressure regulator arranged upstream of a fixed throttle. Compared to DE-OS 30 05 784, very complex electronic components in the form of the differential pressure converter and an A / D converter connected downstream of it are avoided.

Durch die erfindungsgemäße Konstruktion wird somit eine im Vergleich zu vorbekannten Gasregelein­richtungen preisgünstiges Gerät geschaffen, das nichtsdestoweniger eine reproduzierbare Einstellung von vorgegebenen Strömungsmengen gestattet.The construction according to the invention thus creates a device which is inexpensive in comparison with previously known gas control devices and which nonetheless permits a reproducible setting of predetermined flow rates.

Weitere Ausgestaltungen der Erfindung sind in den Unteransprüchen gekennzeichnet.Further refinements of the invention are characterized in the subclaims.

Ein Ausführungsbeispiel der Erfindung ist in den Abbildungen dargestellt und wird nachfolgend anhand der Bezugszeichen im einzelnen erläutert und be­schrieben. Es zeigen

  • Fig. 1 ein Blockschaltbild der erfindungsge­mäßen Gasregeleinrichtung.
  • Fig. 2a,b einen Längsschnitt bzw. Querschnitt durch einen Strömungsmesser in der Gas­regeleinrichtung nach Fig. 1; und
  • Fig. 3 eine schematische Darstellung der Anord­nung der Strömungsmesser nach Fig. 2 in der Gasregeleinrichtung nach Fig. 1.
An embodiment of the invention is shown in the figures and is explained and described in detail below with reference to the reference numerals. Show it
  • Fig. 1 is a block diagram of the gas control device according to the invention.
  • 2a, b show a longitudinal section or cross section through a flow meter in the gas control device according to FIG. 1; and
  • 3 shows a schematic illustration of the arrangement of the flow meter according to FIG. 2 in the gas control device according to FIG. 1.

Die Gasregeleinrichtung enthält nach dem Blockschalt­bild von Fig. 1 einen ersten Anschluß 10, an welchen ein erstes Oxidans in Form von Druckluft anschließbar ist, einen zweiten Anschluß 12, der mit einer Quelle von Lachgas als zweitem Oxidans verbindbar ist. Ein dritter Anschluß 14 ist mit einer Quelle von Brenn­gas, vorzugsweise von Acetylen, verbindbar. An jeden der drei Anschlüsse 10, 12 und 14 ist ein Drucksensor 16, 18 bzw. 20 angeschlossen. Die Drucksensoren 16, 18, 20 signalisieren, ob Gasdruck an dem betreffenden Anschluß ansteht. Diese Signale sind über Signallei­tungen 22, 24 bzw. 26 auf eine Steuereinheit 28 ge­schaltet. Die Steuereinheit 28 ist eine mikroprozessor­gesteuerte Elektronik entsprechend dem Hauptpatent ..... (Patentanmeldung P 34 07 552.6).According to the block diagram of FIG. 1, the gas control device contains a first connection 10, to which a first oxidant in the form of compressed air can be connected, a second connection 12, which can be connected to a source of laughing gas as the second oxidant. A third connection 14 can be connected to a source of fuel gas, preferably acetylene. A pressure sensor 16, 18 and 20 is connected to each of the three connections 10, 12 and 14. The pressure sensors 16, 18, 20 signal whether gas pressure is present at the connection in question. These signals are connected to a control unit 28 via signal lines 22, 24 or 26. The control unit 28 is a microprocessor-controlled electronics according to the main patent ..... (patent application P 34 07 552.6).

Dem ersten Anschluß 10 ist ein als Magnetventil ausge­bildetes Absperrventil 30 nachgeschaltet, das über eine Steuerleitung 32 von der Steuereinheit 28 gesteuert und im stromlosen Zustand abgesperrt ist.The first connection 10 is followed by a shut-off valve 30 designed as a solenoid valve, which is controlled by the control unit 28 via a control line 32 and is shut off in the de-energized state.

Ein 3/2-Wegeventil 34 ist als Magnetventil ausgebildet und über eine Steuerleitung 36 ebenfalls von der Steuer­einheit 28 gesteuert. Das 2/3-Wegeventil 34 verbindet in seiner ersten Schaltstellung den ersten Anschluß 10 und das diesem nachgeschaltete Absperrventil 30 mit einer Leitung 38, während der zweite Anschluß 12 abge­sperrt ist. In seiner zweiten Schaltstellung verbindet das 3/2-Wegeventil 34 den zweiten Anschluß 12 mit der Leitung 38, während die Verbindung zu dem Absperrventil 30 und dem ersten Anschluß 10 abgesperrt ist. Im strom­losen Zustand befindet sich das 3/2-Wegeventil in seiner ersten Schaltstellung, die in Fig. 1 dargestellt ist.A 3/2-way valve 34 is designed as a solenoid valve and is also controlled by the control unit 28 via a control line 36. In its first switching position, the 2/3 directional valve 34 connects the first connection 10 and the shut-off valve 30 connected downstream thereof to a line 38, while the second connection 12 is closed. Connects in its second switching position the 3/2-way valve 34 the second port 12 with the line 38, while the connection to the shut-off valve 30 and the first port 10 is shut off. In the de-energized state, the 3/2-way valve is in its first switching position, which is shown in Fig. 1.

Von.der Leitung 38 führt eine Zweigleitung 39 über einen Druckregler 37 zu einem Zerstäuber. Zwischen dem Absperrventil 30 und dem 3/2-Wegeventil 34 ist ein Speichervolumen 41 angeschlossen.Von.der 38 leads a branch line 39 via a pressure regulator 37 to an atomizer. A storage volume 41 is connected between the shut-off valve 30 and the 3/2-way valve 34.

Die Leitung 38 führt zu einem Druckregler 40. Der Aus­gang des Druckreglers 40 ist über eine fest Drossel 44 mit einem Oxidansanschluß des Brenners verbunden. Der Druckregler 40 ist ein übliches Druckmindererventil, dessen Sollwert über eine Stellspindel veränderbar ist. Die Stellspindel ist durch einen Stellmotor 46 verstell­bar. Der Stellmotor 46 oder geeignete Abgriffmittel geben Stellungssignale an die Steuereinheit 28. Der Stellmotor 46 wird dementsprechend von der Steuer­einheit 28 gesteuert. Das ist durch eine Leitung 48 dargestellt.The line 38 leads to a pressure regulator 40. The output of the pressure regulator 40 is connected via a fixed throttle 44 to an oxidant connection of the burner. The pressure regulator 40 is a conventional pressure reducing valve, the setpoint of which can be changed via an adjusting spindle. The adjusting spindle can be adjusted by an actuator 46. The servomotor 46 or suitable tapping means give position signals to the control unit 28. The servomotor 46 is accordingly controlled by the control unit 28. This is represented by a line 48.

Dem dritten Anschluß 14 ist ein als Magnetventil ausge­bildetes Absperrventil 50 nachgeschaltet. Das Absperr­ventil wird über eine Leitung 52 von der Steuereinheit 28 gesteuert. Über das Absperrventil 50 ist der dritte Anschluß 14 mit einem Druckregler 54 verbunden. Der Druckregler 54 ist ebenfalls ein übliches Druckminderer­ventil wie der Druckregler 40. Eine Stellspindel des Druckreglers 54 zur Verstellung des Sollwerts ist durch einen Stellmotor 56 verstellbar. Der Stellmotor 56 oder geeignete Abgriffmittel geben Stellungssignale an die Steuereinheit 28. Der Stellmotor 56 wird dementsprechend von der Steuereinheit 28 gesteuert. Der Ausgang des Druckreglers 54 ist über eine feste Drossel 58 mit einem Brenngasanschluß des Brenners verbunden.The third connection 14 is followed by a shut-off valve 50 designed as a solenoid valve. The shut-off valve is controlled by the control unit 28 via a line 52. The third connection 14 is connected to a pressure regulator 54 via the shut-off valve 50. The pressure regulator 54 is also a conventional pressure reducing valve like the pressure regulator 40. An adjusting spindle of the pressure regulator 54 for adjusting the setpoint is adjustable by means of a servomotor 56. The servomotor 56 or suitable tapping means give position signals to the control unit 28. The servomotor 56 is accordingly controlled by the control unit 28. The exit of the Pressure regulator 54 is connected to a fuel gas connection of the burner via a fixed throttle 58.

Dem Druckregler 37 in der Zweigleitung 39 ist über eine Drossel 37 ein Strömungsmesser 43 nachgeschaltet, dessen Signal­leitung 43' an die Steuereinheit 28 angeschlossen ist. Dem Druckregler 40 ist über die Drossel 44 ein Strömungsmesser 45 nachgeschaltet, dessen Signalleitung 45' an die Steuereinheit 28 angeschlossen ist. Dem Druckregler 54 ist über Drossel 58 ein Strömungsmesser 59 nachgeschaltet, dessen Signalleitung 59' an die Steuereinheit 28 angeschlossen ist.The pressure regulator 37 in the branch line 39 is followed by a flow meter 43 via a throttle 37, the signal line 43 'of which is connected to the control unit 28. A flow meter 45, whose signal line 45 ′ is connected to the control unit 28, is connected downstream of the pressure regulator 40 via the throttle 44. A flow meter 59, whose signal line 59 'is connected to the control unit 28, is connected downstream of the pressure regulator 54 via throttle 58.

Jeder Strömungsmesser 43,45,59 ist in der in Fig. 2a,b dargestellten Weise aufgebaut. In einem allseitig ge­schlossenen Gehäuse 47 ist ein Turbinenrad 49 mit Flügeln 51 drehbar in Lagern 53 gelagert. Ein Gasein­tritt 55 ist düsenartig ausgebildet und tangential zu den Flügeln 51 des Turbinenrades 49 ausgerichtet. Ein Gasaustritt 57 des Gehäuses 47 ist an die zu dem Zerstäuber, dem Oxidansanschluß oder dem Brenngas­anschluß des Brenners führende Leitung angeschlossen.Each flow meter 43, 45, 59 is constructed in the manner shown in FIGS. 2a, b. A turbine wheel 49 with vanes 51 is rotatably mounted in bearings 53 in a housing 47 which is closed on all sides. A gas inlet 55 is designed like a nozzle and is oriented tangentially to the vanes 51 of the turbine wheel 49. A gas outlet 57 of the housing 47 is connected to the line leading to the atomizer, the oxidant connection or the fuel gas connection of the burner.

Jeder Strömungsmesser 43,45,49 enthält mit dem Turbinenrad 49 zusammenwirkende Mittel zur Erzeugung von Signalen zur Anzeige der Gasströmung. In dem dargestellten Ausführungsbeispiel ist das Turbinenrad 49 mit zwei diametral gegenüberliegend angeordneten Magneten 61 versehen, die z.B. in den Kunststoff eingebettet sein können, aus dem das Tur­binenrad 49 besteht. In dem Gehäuse 47 ist im Wirkungs­bereich der Magnete 61 ein Hall-Sensor 63 angeordnet, der mit der jeweiligen Signalleitung 43',45' oder 59' verbunden ist.Each flow meter 43, 45, 49 contains means for interacting with the turbine wheel 49 for generating signals for indicating the gas flow. In the exemplary embodiment shown, the turbine wheel 49 is provided with two diametrically opposite magnets 61 which can be embedded, for example, in the plastic from which the turbine wheel 49 is made. A Hall sensor 63 is arranged in the housing 47 in the area of action of the magnets 61. which is connected to the respective signal line 43 ', 45' or 59 '.

Bei Drehung des Turbinenrades 49 wird am Hall-Sensor 63 ein Ausgangssignal erzeugt, wenn einer der an dem Turbinenrad 49 angeordneten Magnete 61 an dem Hall-­Sensor 63 vorbeiläuft. Die Frequenz dieser Ausgangs­signale ist abhängig von der Drehgeschwindigkeit des Turbinenrades 49 und damit von der Strömungsgeschwindig­keit des Gases, daß durch den Gaseintritt 55 auf das Turbinenrad 49 trifft. Das Auftreten dieser Ausgangs­signale kann in verschiedener Weise zur Bestimmung der Strömungsgeschwindigkeit des Gases genutzt werden. So kann z.B. die Zeit zwischen dem Auftreten zweier aufeinanderfolgender Ausgangssignale bestimmt werden. Bei einer solchen Anordnung ist die Strömungsgeschwin­digkeit S, die z.B. in l/min angegeben werden kann, durch die Zahl N der zwischen zwei aufeinanderfolgenden Ausgangssignalen des Hall-Sensors 63 gezählten Impulse eines Zählers nach folgender Beziehung bestimmt:
S = K · N -m .When the turbine wheel 49 rotates, an output signal is generated at the Hall sensor 63 when one of the magnets 61 arranged on the turbine wheel 49 passes the Hall sensor 63. The frequency of these output signals is dependent on the rotational speed of the turbine wheel 49 and thus on the flow speed of the gas that strikes the turbine wheel 49 through the gas inlet 55. The occurrence of these output signals can be used in various ways to determine the flow velocity of the gas. For example, the time between the occurrence of two successive output signals can be determined. In such an arrangement, the flow rate S, which can be specified, for example, in l / min, is determined by the number N of the pulses of a counter counted between two successive output signals of the Hall sensor 63 according to the following relationship:
S = K · N -m .

Darin sind K und m Parameter, die empirisch für die verschiedenen Anordnungen bestimmt werden. Diese Parameter sind in ihrem Wert z.B. von der Struktur des Gaseintritts 55 in dem Gehäuse 47, vom Aufbau des Gehäuses 47 und von der Form des Turbinen­rades 49 abhängig. Diese Parameter, vor allem K, sind auch von der Art und Zusammensetzung des Gases ab­hängig, das durch das Gehäuse 47 fließt und das Turbinenrad 49 antreibt. Jedoch lassen sich die Para­meter mit hoher Genauigkeit für jede Anordnung und jedes Gas bestimmen, so daß mit dem Strömungsmesser der angegebenen Art die Gasströmungen mit großer Genauigkeit gemessen und über die Steuereinheit 28 und die Druckregler 37,40,54 reproduzierbar einge­stellt werden können.There are K and m parameters that are determined empirically for the different arrangements. The value of these parameters depends, for example, on the structure of the gas inlet 55 in the housing 47, on the structure of the housing 47 and on the shape of the turbine wheel 49. These parameters, especially K, are also dependent on the type and composition of the gas flowing through the housing 47 and that Turbine wheel 49 drives. However, the parameters can be determined with high accuracy for each arrangement and each gas, so that the gas flows of the specified type can be measured with great accuracy and reproducibly adjusted via the control unit 28 and the pressure regulator 37, 40, 54.

Anstelle der Magnete 61 und des Hall-Sensors 63, die besonders einfache und leicht zu verwirklichende signalerzeugende Mittel darstellen, können auch andere, bevorzugt berührungslos arbeitende signal­erzeugende Mittel verwendet werden, die eine Be­stimmung der Drehgeschwindigkeit des Turbinenrades 47 ermöglichen.Instead of the magnets 61 and the Hall sensor 63, which represent particularly simple and easy-to-implement signal-generating means, other, preferably non-contact, signal-generating means can also be used, which enable the rotational speed of the turbine wheel 47 to be determined.

Die in die Steuereinheit 28 eingegebenen Ausgangs­signale der Hall-Sensoren 63 werden in der Steuer­einheit 28 verarbeitet, das heißt mit für bestimmte Gegebenheiten, z.B. Luft oder Lachgas als Oxidans, gespeicherten oder vorgegebenen Sollwerten verglichen. Bei Abweichungen von Sollwerten werden die jeweiligen Regler 37,40,54 über die zugehörigen Stellmotoren 37', 46 und 56 verstellt. Die dazu notwendigen Programm­schritte können ohne weiteres in die Programmierung der Steureinheit 28 eingearbeitet werden und bedürfen an dieser Stelle keiner weiteren Erläuterung.The output signals of the Hall sensors 63 input into the control unit 28 are processed in the control unit 28, i.e. for certain circumstances, e.g. Air or nitrous oxide compared as an oxidant, stored or specified target values. In the event of deviations from target values, the respective controllers 37, 40, 54 are adjusted via the associated servomotors 37 ', 46 and 56. The program steps required for this can easily be incorporated into the programming of the control unit 28 and do not require any further explanation at this point.

Eine vorteilhafte Anordnung der Strömungsmesser ist schematisch in Fig. 3 dargestellt. Die Gehäuse 47 der drei Strömungsmesser 43,45 und 59 sind dabei gemeinsam zu einem Block 69 angeordnet, der unmittelbar mit den Druckreglern 37,40,und 54 verbunden ist. In diesem Fall werden die Gaseintritte 55 der einzelnen Gehäuse 47 in dem Block 69 von Strömungsdrosseln nach Art der Strömungsdrosseln 44 und 58 gebildet. An dem Block 69 sind die Gasaustritte 57 angeordnet, an die sich un­mittelbar die Leitungen zum Zerstäuber, dem Oxidans­anschluß und zum Brenngasanschluß des Brenners an­schließen.An advantageous arrangement of the flow meters is shown schematically in FIG. 3. The housings 47 of the three flow meters 43, 45 and 59 are arranged together to form a block 69 which is directly connected to the pressure regulators 37, 40, and 54. In this case, the gas inlets 55 of the individual housings 47 in the block 69 are formed by flow restrictors in the manner of the flow restrictors 44 and 58. At block 69 the gas outlets 57 are arranged, to which the lines to the atomizer, the oxidant connection and the fuel gas connection of the burner are connected directly.

Das Gehäuse 47 als ganzes oder seine Teile im Bereich des Turbinenrades 49 können aus einem unmagnetischen Metall bestehen. Dadurch wird das Turbinenrad 49 durch Wirbelströme gebremst, die durch die Drehung des Tur­binenrades hervorgerufen werden. Das hat den Vorteil, daß die Lebensdauer der Einrichtung erhöht und die Frequenz der vom Hall-Sensor 63 erzeugten Signale niedrig gehalten wird, wodurch sich die Meßgenauigkeit erhöht.The housing 47 as a whole or its parts in the region of the turbine wheel 49 can consist of a non-magnetic metal. As a result, the turbine wheel 49 is braked by eddy currents which are caused by the rotation of the turbine wheel. This has the advantage that the service life of the device is increased and the frequency of the signals generated by the Hall sensor 63 is kept low, which increases the measuring accuracy.

Claims (4)

1. Gasregeleinrichtung zur Regelung der Brenngas- und Oxidanszufuhr zu einem Brenner bei einem Atomabsorptions-Spektrometer, enthaltend
(a) je eine Drossel (37'',44,58) für Brenngas und Oxidans und
(b) je einen der Drossel (37'',44,58) vorge­schalteten Druckregler (37,40,54) für Brenngas und Oxidans,
bei welcher
(c) die Drosseln (37'',44,58) für Brenngas und Oxidans feste Durchflußquerschnitte haben,
(d) die Sollwerte der Druckregler (37,40,54) durch je einen Stellmotor (37',46,56) re­produzierbar einstellbar sind und
(e) eine Steuereinheit (28) mit einer mikro­prozessorgesteuerten Elektronik vorgesehen ist, durch welche die Stellmotore (37',46, 56) in reproduzierbarer Weise steuerbar sind,
dadurch gekennzeichnet, daß
(f) jedem Druckregler (37,44,58) ein Turbinen­rad-Strömungsmesser (43,45,59) nachge­schaltet ist,
(g) an dem Turbinenrad-Strömungsmesser (43,44, 58) signalerzeugende Mittel vorgesehen sind, die mit dem Turbinenrad (49) zur Erzeugung von Ausgangsimpulsen zusammen­wirken, deren Frequenz der Drehzahl des Turbinenrades (49) proportional ist,
(h) die Ausgangsimpulse auf die Steuereinheit (28) zur Bildung eines digitalen Strö­mungsgeschwindigkeitssignals aufgeschaltet sind und
(i) die Sollwerte der Druckregler (37,44,58) über die von der Steuereinheit (28) an­steuerbaren Stellmotore (37',46,56) im Sinne der Einhaltung vorgegebener Strö­mungsgeschwindigkeits-Sollwerte veränder­bar sind.1. Gas control device for controlling the fuel gas and oxidant supply to a burner in an atomic absorption spectrometer, containing
(a) a throttle (37 '', 44.58) for fuel gas and oxidant and
(b) one each of the throttle (37 '', 44.58) upstream pressure regulator (37.40.54) for fuel gas and oxidant,
in which
(c) the throttles (37 ″, 44.58) for fuel gas and oxidant have fixed flow cross sections,
(d) the setpoints of the pressure regulators (37, 40, 54) are reproducibly adjustable by means of a servomotor (37 ', 46, 56) and
(e) a control unit (28) with microprocessor-controlled electronics is provided, by means of which the servomotors (37 ', 46, 56) can be controlled in a reproducible manner,
characterized in that
(f) a turbine wheel flow meter (43, 45, 59) is connected downstream of each pressure regulator (37, 44, 58),
(g) signal-generating means are provided on the turbine wheel flow meter (43, 44, 58), which cooperate with the turbine wheel (49) to generate output pulses, the frequency of which is proportional to the rotational speed of the turbine wheel (49),
(h) the output pulses are applied to the control unit (28) to form a digital flow rate signal and
(i) the setpoints of the pressure regulators (37, 44, 58) can be changed via the servomotors (37 ', 46, 56) which can be controlled by the control unit (28) in order to maintain specified flow rate setpoints. 2. Gasregeleinrichtung nach Anspruch 1, dadurch gekennzeichnet, daß die besagten festen Drosseln (37',44,58) für Brenngas und Oxidans düsenartig ausgebildet und so in einem Gehäuse (47) des Turbinenrad-Strömungsmessers (43,45, 59) angeordnet sind, daß das Turbinenrad (49) des Turbinenrad-Strömungsmessers (43,45,49) von dem aus der Drossel (37',44,58) austretenden Gasstrom angeblasen wird.2. Gas control device according to claim 1, characterized in that said fixed throttles (37 ', 44,58) for fuel gas and oxidant are nozzle-like and are arranged in a housing (47) of the turbine wheel flow meter (43, 45, 59) that the turbine wheel (49) of the turbine wheel flow meter (43, 45, 49) is blown by the gas stream emerging from the throttle (37 ', 44, 58). 3. Gasregeleinrichtung nach Anspruch 2, dadurch gekennzeichnet, daß (a) das Turbinenrad (49) des Turbinenrad-­Strömungsmessers jeweils in einem Gehäuse (47) gelagert ist, das wenigstens im Bereich des Turbinenrades (49) aus einem unmagnetischen Metall besteht, und (b) die signalerzeugenden Mittel von min­destens einem, an dem Turbinenrad (49) angebrachten Magneten (61) und einem auf der Außenseite des Gehäuses (47) ange­brachten Hall-Sensor (63) gebildet sind. 3. Gas control device according to claim 2, characterized in that (a) the turbine wheel (49) of the turbine wheel flow meter is in each case mounted in a housing (47) which consists of a non-magnetic metal at least in the region of the turbine wheel (49), and (b) the signal-generating means are formed by at least one magnet (61) attached to the turbine wheel (49) and a Hall sensor (63) attached to the outside of the housing (47). 4. Gasregeleinrichtung nach Anspruch 3, dadurch gekennzeichnet, daß an dem Turbinenrad (49) zwei diametral einander gegenüberliegend angeordnete Magnete (61) vorgesehen sind.4. Gas control device according to claim 3, characterized in that two diametrically opposite magnets (61) are provided on the turbine wheel (49).
EP19860111215 1984-03-01 1986-08-13 Device for regulating the fuel and oxidant gas supply for a burner of an atomic absorption spectrometer Expired - Lifetime EP0212567B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19843407552 DE3407552A1 (en) 1984-03-01 1984-03-01 GAS CONTROL DEVICE FOR CONTROLLING THE FUEL GAS AND OXIDE SUPPLY TO A BURNER IN AN ATOMIC ABSORPTION SPECTROMETER
DE3529547 1985-08-17
DE19853529547 DE3529547A1 (en) 1984-03-01 1985-08-17 GAS CONTROL DEVICE FOR CONTROLLING THE FUEL GAS AND OXIDE SUPPLY TO A BURNER IN AN ATOMIC ABSORPTION SPECTROMETER

Publications (3)

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EP0212567A2 true EP0212567A2 (en) 1987-03-04
EP0212567A3 EP0212567A3 (en) 1989-03-29
EP0212567B1 EP0212567B1 (en) 1990-04-11

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EP (1) EP0212567B1 (en)
JP (2) JPH0660872B2 (en)
AU (1) AU586699B2 (en)
DE (2) DE3407552A1 (en)
GB (1) GB2155205B (en)

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Publication number Publication date
EP0212567A3 (en) 1989-03-29
AU586699B2 (en) 1989-07-20
DE3407552C2 (en) 1987-10-22
GB2155205A (en) 1985-09-18
DE3407552A1 (en) 1985-09-05
GB2155205B (en) 1987-12-16
AU6150486A (en) 1987-02-19
GB8501762D0 (en) 1985-02-27
JPS6298238A (en) 1987-05-07
DE3529547C2 (en) 1987-12-17
US4681530A (en) 1987-07-21
JPH0660872B2 (en) 1994-08-10
US4640677A (en) 1987-02-03
JPS60205237A (en) 1985-10-16
JPH0750028B2 (en) 1995-05-31
DE3529547A1 (en) 1987-02-26
EP0212567B1 (en) 1990-04-11

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