EP0255915A2 - Photomètre à flammes avec régulation constante d'écoulement - Google Patents

Photomètre à flammes avec régulation constante d'écoulement Download PDF

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Publication number
EP0255915A2
EP0255915A2 EP87110967A EP87110967A EP0255915A2 EP 0255915 A2 EP0255915 A2 EP 0255915A2 EP 87110967 A EP87110967 A EP 87110967A EP 87110967 A EP87110967 A EP 87110967A EP 0255915 A2 EP0255915 A2 EP 0255915A2
Authority
EP
European Patent Office
Prior art keywords
pressure
control
throttle
differential pressure
flame photometer
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
EP87110967A
Other languages
German (de)
English (en)
Other versions
EP0255915B1 (fr
EP0255915A3 (en
Inventor
Joachim Dr. Rer. Nat. Dipl.-Phys. Slupek
Thomas Dipl.-Ing. Müller
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.)
Eppendorf SE
Original Assignee
Eppendorf Netheler Hinz GmbH
Eppendorf Geraetebau Netheler and Hinz GmbH
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 Eppendorf Netheler Hinz GmbH, Eppendorf Geraetebau Netheler and Hinz GmbH filed Critical Eppendorf Netheler Hinz GmbH
Priority to AT87110967T priority Critical patent/ATE62746T1/de
Publication of EP0255915A2 publication Critical patent/EP0255915A2/fr
Publication of EP0255915A3 publication Critical patent/EP0255915A3/de
Application granted granted Critical
Publication of EP0255915B1 publication Critical patent/EP0255915B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/02—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
    • F23N5/08—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using light-sensitive elements
    • F23N5/082—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using light-sensitive elements using electronic means

Definitions

  • the invention relates to a flame photometer of the type mentioned in the preamble of claim 1.
  • Flame photometers with constant flow control of at least one of the fuel gas components enable the setting of a flame that burns with constant brightness over time, which permits a constant measurement evaluation of the spectral lines generated by test substances introduced into the flame. This enables accurate and reproducible measurements. It should be noted that both long-term constancy and short-term constancy must be given in order to enable evaluable measured values.
  • reducing valves that control a valve with a differential pressure controlled membrane.
  • the membrane is acted upon by the atmosphere on the one hand, which mostly corresponds essentially to the pressure behind the throttle, and on the other hand by the pressure in the buffer tank via the outlet line of the valve.
  • the membrane regulates the actual valve of the reducing valve to a middle position with a constant flow, which results in a uniform gas flow. Disturbing flutter of such a reducing valve should be avoided if possible.
  • the object of the present invention is therefore to provide a flame photometer of the type mentioned at the outset, which can be designed much more cost-effectively, precisely and reliably with regard to constant flow control.
  • a control valve is provided as the control valve, which does not work continuously like the reducing valves previously used, but digitally with only two switch positions OPEN and CLOSE.
  • Such a switching valve can therefore be controlled digitally in the technology customary today and, in a simple adaptation, allows the use of digital control and regulating devices which can be connected to computer controls in a simple manner.
  • the switching valve according to the invention is distinguished by considerable cost advantages and, owing to its simple design, by significantly reduced susceptibility to faults. Due to the buffer tank downstream of the switching valve, the pressure and flow fluctuations resulting from the discontinuous operation of the switching valve are evened out. With different control technology of the switching valve, which will be dealt with in the following (e.g.
  • the invention is therefore based on the knowledge that a switching valve for flame photometers previously not considered usable for the present purposes can be used, namely in a functional unit with a buffer tank, whereby a constant, constant gas supply is made possible by the interaction of the switching valve and the buffer tank.
  • the features of claim 2 are advantageously provided.
  • a certain pressure hysteresis is permitted here so that the differential pressure oscillates between two specified values when the switching valve is working.
  • the pressure hysteresis can be chosen to be very small.
  • the circuit complexity can be kept very low in such an operating mode.
  • the switching frequency of the switching valve in this operating mode depends on the volume of the buffer tank. If the volume is very large, the valve switches very slowly.
  • the switching valve and control can be designed accordingly simply and inexpensively.
  • the gas flow control shown in the figure is provided in a flame photometer, the other parts of which are omitted for the sake of simplicity.
  • gas is supplied to the burner via a gas line 1 in the direction of the arrow 2 fed.
  • the gas conducted via the gas line 1 can be a combustible gas mixture or one of the gas components required for combustion (fuel gas, oxidant).
  • the gas flowing through is to be kept constant in the flow with the control shown, so that the burner 2 operates at a constant time.
  • a switching valve 3 is interposed in the gas line 1 and, as indicated by corresponding switching symbols, has the two switching positions OPEN and CLOSE. It is operated electrically and is controlled cyclically via a control line 4.
  • a buffer tank 5 is connected downstream of the switching valve 3 in the gas line 1.
  • the gas pressure in the container 5 is fed via a line 6 to a pressure / voltage converter 7 which is connected via a line 8 to an input of a control device 9.
  • This compares the pressure value in the container 5 with a predetermined target value and regulates the duty cycle OPEN / CLOSE of the switching valve 3 accordingly via the control line 4 such that the pressure in the container 5 is kept essentially constant.
  • a throttle 10 is connected downstream of the container 5, through which the gas flows to the burner 2 via the gas line 1.
  • the flow resistance of the burner 2 indicated in the figure with the corresponding symbol is with flame photometers usually very small and even.
  • the gas line 1 therefore, there is generally a constant pressure essentially corresponding to the atmospheric pressure at the point between the throttle 10 and the burner 2.
  • the pressure difference between the inlet and outlet at the throttle 10 is thus kept constant by the pressure control in the container 5. Therefore, the flow through the throttle 10 and thus the total gas flow in the desired sense is constant.
  • a throttle 10 is to be used which has a resistance to the flow resistance of the burner 2 (inclusive of the gas line system between the throttle 10 and the burner 2) has considerably greater flow resistance.
  • the total pressure drop between the container 5 and the outlet 11 of the burner into the atmosphere is then determined by the flow resistance of the throttle 10, against which the flow resistance of the burner 2 can be neglected. Changes in the resistance at the burner 2 then result in only negligibly small changes in flow.
  • the control device 9 detects only the pressure in the container 5, that is to say the admission pressure of the throttle 10, via the pressure / voltage converter 7.
  • the atmospheric pressure is taken into account as the pressure behind the throttle 10.
  • the pressure / voltage converter 7 can in Usually be designed so that it compares the pressure on the line 6 with the atmospheric pressure and converts the differential pressure and passes it on to the controller 9.
  • a second pressure / voltage converter 12 is connected via a line 13, which is connected via a line 14 in parallel to the line 8 of the converter 7 to the control device 9, which in this case works as a differential circuit and the cycle ratio of the switching valve 3 readjusted such that the pressure difference between the gas pressures in lines 6 and 13, that is to say at the inlet and outlet of the throttle 10, remains constant.
  • the pressure / voltage converter 7 which is always present anyway, is a differential pressure sensor, one pressure input of which is connected to the container 5 and the other of which is connected to the atmosphere, this converter 7 can also be used in a simplified embodiment to determine the differential pressure across the throttle 10 will. For this purpose, one of its pressure inputs is connected to line 6 and its other pressure input is connected to line 13. The difference found pressure is converted into voltage and supplied to the control device 9 as an input variable. In this way, the second converter 12 can be saved when determining the differential pressure.
  • the switching valve 3 can be a pressure reducer, for. B. in the form of a further throttle, upstream to reduce the high feed pressure, for example a gas bottle, to a pressure level that can be processed by the switching valve 3.
  • the control device 9 is preferably designed as an electronic control device which compares the control variable arriving via line 8 or the difference between the control variables arriving via line 8 and 14 with an electrically predetermined setpoint value and, in the event of deviations, readjusts the cycle ratio of the switching valve accordingly via control line 4 .
  • an adjusting device for example in the form of a setting potentiometer 15, can preferably be provided, with which the electrical setpoint specification can be adjusted. In this way, the pressure in the container 5 or the differential pressure at the throttle 10 and thus the desired value of the gas flow to be kept constant can be set to the desired value, for example in order to obtain the desired flame size in the burner 2.
  • the adjustment device mentioned for the control device 9 can, for example, also be designed as a preselection control, with which certain preset flows can be selected, for example, by pressing a key. It can also be a control done from a computer, e.g. B. according to a certain program. In this way it is possible to select certain flows depending on the requirements, for example depending on the measurement method currently used in the flame photometer, for example if different flame intensities are required for different photometric methods.
  • the control device 9 can control the switching valve 3 as a function of the differential pressure at the throttle 10 in different operating modes.
  • a construction that is very simple to implement in terms of circuitry, which has proven itself in tests, consists in switching on the switching valve 3 when the pressure falls below a first, and switching on when a predetermined higher pressure is exceeded. This results in a pressure fluctuating in the container 5 between the two predetermined pressure values, although this hysteresis can be kept very small. If the volume of the container is large enough, the switching valve 3 works very slowly. The control and the switching valve can therefore be constructed very simply.
  • the switching valve can be controlled at a constant switching frequency with different pulse widths, that is to say, for example, with different lengths of the open time.
  • the repetition frequency can also be changed if the open time is constant.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Feeding And Controlling Fuel (AREA)
EP87110967A 1986-08-06 1987-07-29 Photomètre à flammes avec régulation constante d'écoulement Expired - Lifetime EP0255915B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT87110967T ATE62746T1 (de) 1986-08-06 1987-07-29 Flammenphotometer mit konstantflussregelung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3626644 1986-08-06
DE3626644 1986-08-06

Publications (3)

Publication Number Publication Date
EP0255915A2 true EP0255915A2 (fr) 1988-02-17
EP0255915A3 EP0255915A3 (en) 1988-10-05
EP0255915B1 EP0255915B1 (fr) 1991-04-17

Family

ID=6306810

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87110967A Expired - Lifetime EP0255915B1 (fr) 1986-08-06 1987-07-29 Photomètre à flammes avec régulation constante d'écoulement

Country Status (3)

Country Link
EP (1) EP0255915B1 (fr)
AT (1) ATE62746T1 (fr)
DE (1) DE3769395D1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4110343A1 (de) * 1990-03-30 1991-10-02 Hitachi Ltd Plasmaanalysator fuer die spurenelementanalyse
EP0836054A1 (fr) * 1996-10-11 1998-04-15 Gaggenau Hausgeräte GmbH Procédé et dispositif de commande de la grandeur de la flamme des appareils de cuisson à gaz

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2200487A1 (fr) * 1972-09-14 1974-04-19 Vaillant Joh Kg
DE3005784A1 (de) * 1979-03-05 1980-09-18 Perkin Elmer Corp Mess- und steuersystem fuer den fluidfluss in einem brenner fuer die atomspektroskopie
EP0068589A1 (fr) * 1981-06-23 1983-01-05 Conma N.V. Méthode et dispositif pour le contrôle de la pression d'un fluide et/ou pour le débit d'un écoulement
GB2155205A (en) * 1984-03-01 1985-09-18 Bodenseewerk Perkin Elmer Co Gas control device for a burner for an atomic absorption spectrometer

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2200487A1 (fr) * 1972-09-14 1974-04-19 Vaillant Joh Kg
DE3005784A1 (de) * 1979-03-05 1980-09-18 Perkin Elmer Corp Mess- und steuersystem fuer den fluidfluss in einem brenner fuer die atomspektroskopie
EP0068589A1 (fr) * 1981-06-23 1983-01-05 Conma N.V. Méthode et dispositif pour le contrôle de la pression d'un fluide et/ou pour le débit d'un écoulement
GB2155205A (en) * 1984-03-01 1985-09-18 Bodenseewerk Perkin Elmer Co Gas control device for a burner for an atomic absorption spectrometer

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4110343A1 (de) * 1990-03-30 1991-10-02 Hitachi Ltd Plasmaanalysator fuer die spurenelementanalyse
EP0836054A1 (fr) * 1996-10-11 1998-04-15 Gaggenau Hausgeräte GmbH Procédé et dispositif de commande de la grandeur de la flamme des appareils de cuisson à gaz

Also Published As

Publication number Publication date
DE3769395D1 (de) 1991-05-23
EP0255915B1 (fr) 1991-04-17
EP0255915A3 (en) 1988-10-05
ATE62746T1 (de) 1991-05-15

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