US3592608A - Analytical instrument - Google Patents

Analytical instrument Download PDF

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Publication number
US3592608A
US3592608A US775985A US3592608DA US3592608A US 3592608 A US3592608 A US 3592608A US 775985 A US775985 A US 775985A US 3592608D A US3592608D A US 3592608DA US 3592608 A US3592608 A US 3592608A
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United States
Prior art keywords
sample
venturi
barrel
fuel gas
flame
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US775985A
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English (en)
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John U White
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
    • G01N21/72—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited using flame burners

Definitions

  • An analytical instrument including a flame source and a detection system for the qualitative and quantitative emission or absorption analysis of a sample.
  • the sample is atomized and mixed with an appropriate fuel gas, and the mixture is led through an angularly disposed burner barrel to a grid for holding the llame.
  • Compressed air is supplied to the atomizer, and a portion of the air is directed to a venturi nozzle which is connected to a supply of the fuel gas.
  • the air is effective to draw the fuel gas through the venturi and into the atomizer at a substantially constant rate irrespective of pressure fluctuations in a gas supply.
  • the instrument additionally includes a screen and baille construction within the angularly extending barrel which is effective to direct large droplets of sample material away from the barrel inlets.
  • This invention relates to analytical instruments and more particularly to llame analyzers adapted for use in llame photometric equipment, such as flame emission and absorbent devices.
  • the presence or absence of the substance may be ascertained by utilizing a monochromator or filter to detect the emitted light from the llame at the selected wave length.
  • the flame also may be analyzed by measuring the light absorbed thereby from an external source, to provide generally similar quantitative or qualitative evaluations of the sample.
  • the term light as used herein, is intended to include, in addition to visible light, radiation having wave lengths both longer and shorter than the visible spectrum.
  • the detection systems for instruments of the foregoing type have high sensitivity, and even comparatively small variations in the llame may lead to errors of large magnitude.
  • the instruments are adversely affected by such factors as variations in the rate at which the fuel gas is supplied to the burner.
  • It of course would be desirable for purposes of simplicity and economy to utilize natural or other fuel Igas from the public gas mains.
  • the normal variations in pressure from these mains have seriously impaired the accuracy of the analytical measurements.
  • One general object of this invention is to provide a new and improved analytical instrument for the qualitative and quantitative emission analysis of a sample.
  • Another object of the invention is to provide a llame analyzer for an atomized sample in which the analysis being made is substantially unaffected by any large droplets of the sample.
  • a further object of the invention is to provide llame analyzing apparatus in which the deposit of unwanted residue from the llame is substantially reduced.
  • Still another object of the invention is to provide a novel analytical instrument of improved accuracy which is economical to manufacture and thoroughly reliable in operation.
  • the apparatus includes an atomizer for receiving a solution containing the sample to be analyzed.
  • a burner grid is disposed in spaced juxtaposition with the atomizer and is connected thereto by an elongated barrel.
  • a suitable fuel gas is mixed with the atomized sample, and the mixture is directed along the barrel to the grid where a substantially clean llame representative of the sample is produced.
  • the llame is monitored by a photoelectric detection system which is responsive to one or more characteristics of the llame to produce an analytical measurement of the characteristic.
  • novel venturi means which is supplied with the fuel gas and communicates with the atomizer.
  • a pressurized stream of air or other combustion supporting gas draws the fuel gas through the venturi and into the burner ⁇ barrel at a substantially constant rate irrespective of pressure fluctuations in the fuel gas supply.
  • a portion of the barrel between the atomizer and the burner grid is disposed at an angle with respect to the horizontal and is provided with a drain outlet adjacent its lower end. This outlet is oriented with respect to the fuel gas inlet and the atomizer such that any large droplets of spray from the atomized sample are automatically removed from the apparatus without clogging or otherwise interfering with either the inlet or the atomizer.
  • a screen and baille structure of unique construction and arrangement is disposed within the barrel and is effective to channel the condensed droplets of sample material toward the drain, thereby further reducing the possibility of interference with the fuel gas inlet and the atomizer.
  • the orientation of the baille within the barrel is such that any large unatomized droplets similarly are deflected toward the drain ⁇ prior to reaching the llame.
  • a supply of clear air or other gas is continuously fed to the lower portion of the burner chimney.
  • the flow of gas is directed along the inside of the chimney to minimize the formation of unwanted residue thereon and to stabilize the flame.
  • FIG. 1 is a schematic representation, with certain portions shown in section, of an analytical instrument in accordance with one illustrative embodiment of the invention
  • FIG. 2 is an enlarged vertical sectional view of an atomizer and burner assembly for the instrument.
  • FIG. 3 is an end elevational view of a portion of the atomizer, as seen from the line 3 3 in FIG. 2.
  • an analytical instrument which comprises a funnel-shaped container 10 for the sample to be analyzed, a combined atomizer-burner having an atomizing section 12, an angularly disposed tube or barrel 14, a burner grid section 16, and a photoelectric detection system 18.
  • the sample is atomized by the atomizing section 12, and the atomized sample, together with a suitable fuel gas and air or other combustion-supporting gas, are directed through the barrel 14 to the grid section 16 to produce a flame 20.
  • the flame is analyzed by the detection system 18 to determine particular characteristics of the sample.
  • the instrument is supplied with natural gas from a gas main indicated schematically at 25.
  • the main 25 is subject to normal pressure fluctuations which vary over a comparatively wide range.
  • the main is connected to a pressure regulator 26. From the regulator 26 the fuel gas is led through a flow control valfve 27 to a venturi nozzle 30.
  • Air under pressure also is introduced into the ⁇ venturi nozzle 30 from a compressor 31, a filter 32, a pressure regulator 33 and a conduit 34.
  • a separate conduit 40 supplies air directly from the regulator 33 to the atomizerburner.
  • the venturi nozzle 30 is physically separate from the atomizer-burner and is connected thereto by a conduit 3S. In other advantageous arrangements, however, the nozzle 30 forms an integral part of the atomizer-burner structure.
  • the atomizing section 12 comprises a block-shaped housing 37 which includes a centrally located chamber 38 and a venturi passage 39 in spaced relationship therewith.
  • the chamber 38 is supplied with compressed air from the y pressure regulator 33 (FIG. l) through a nipple 41 (FIG. 3). A portion of the incoming air is led to the venturi passage 39 through a laterally extending passage 43. The fuel gas is supplied from the valve 27 to a nipple 45 which communicates with the venturi passage 39 intermediate its ends.
  • a hollow needle 47 mounteded within the Venturi passage 39. ⁇ One end of the needle 47 is positioned to receive compressed air from the passage 43, while the opposite or discharge end of the needle is located somewhat beyond the point at which the fuel gas enters the venturi passage 39. Access to the needle 47 and the passagle 39 is provided by a removable plug 48. The end of the passage 39 opposite that connected to the passage 43 communicates with the uppermost portion of a recess 49 in the housing 37.
  • a stainless steel sample tube t extends from within the funnel-shaped container through the central chamber 38 of the atomizing section 12 and is held in place by a plug 51.
  • the tube 50 protrudes into the lower end of the barrel 14 and is surrounded by an atomizing nozzle 52 in spaced relationship therewith.
  • the chamber 38 communicates with the space between the tube 50 and the nozzle 52 to permit an annular stream of compressed air to be directed into the barrel.
  • the barrel 14 is supported at its lower end within the portion of the housing 37 immediately adjacent the annular recess 49.
  • the barrel 14 slopes upwardly from the housing 37 at an acute angle with respect to the horizontal, and the upper portion of the barrel is bent to form a vertically extending end S5 leading to the grid section 16.
  • a narrow baille strip or plate 60 extends in a more or less vertical direction within the barrel 14 a short distance above the atomizing nozzle 52.
  • the plate 60 is of arcuate cross section and is suitably affixed at its lower end to the adjacent portion of the screen 57.
  • the plate is angularly disposed with respect to the axis of the barrel, and its upper end abuts the opposite portion of the screen.
  • a drain outlet 62 extends through the wall of the housing 37 immediately beneath the lower end of the plate 60.
  • the upper end of the barrel 14 terminates in a burner head assembly 65 and is provided with a perforated plate or grid 67.
  • a second grid 68 is spaced above the grid 67 and serves to support the flame 20.
  • the assembly 65 includes a chimney 69 of glass or other transparent material which surrounds the flame. A supply of clean air is led directly from the pressure regulator 33 (FIG. 1) to the interior of the burner head adjacent the base of the chimney through a conduit 72.
  • the detection system 18 includes a lens 75 which is positioned to receive light from a selected part of the flame 20.
  • the light passes through a filter 76 and a second lens 77 to a suitable photocell 78.
  • the photocell 78 illustratively may comprise an iron-selenium cell or a silicon photodiode and is effective to convert the light energy into electrical energy.
  • the electrical energy from the photocell controls a galvanometer 80 or other electrical detector.
  • the second stream of compressed air moves through the lateral passage 43 and into the needle 47.
  • This latter stream is discharged from the needle, it undergoes a drop in pressure which is determined by the dimensions of the various parts.
  • fuel gas is drawn into the passage 39 at a substantially constant rate irrespective of changes in pressure of the gas.
  • the pressure in the gas main 25 (FIG. l) may vary over a comparatively wide range.
  • the pressure regulator 26 provides a rough control over extremely large changes in pressure, the pressure of the gas as it enters the venturi 30 nevertheless may be subject to variations which, if not controlled, would adversely affect the accuracy of the detected measurements.
  • a further advantage that results from the system described above is that the composition of the air and fuel gas mixture is relatively invariant to changes in air pressure as well as to fuel gas pressure changes. Since the air aspirates its own fuel gas, the air-to-gas mixture ratio is almost independent of air pressure. This ratio remains substantially constant irrespective of pressure fluctuations in either the air or fuel gas supply. Other parameters being equal, the amount of sample atomizcd and the size of the llame will vary with changes in air pressure, although these variations are of little moment for several types of measurements. The relative proportion between two different elements in the sample, however is independent of flame size and amount atomized. Accordingly, in cases in which it is desired to avoid the effects of variations in these characteristics, an internal standard may be included in the sample to enable the realization of an extremely accurate measurement.
  • the fuel gas and air mixture is directed at a uniform rate from the venturi 30 into the annular recess 49 and then to the barrel 14.
  • the mixture and the atomized sample from the nozzle 52 flow along the barrel to the burner section 16 and pass through the lower grid 67 and then to the flame grid 68, where ignition takes place to produce the flame 20.
  • the flame is viewed through the chimney 69 by the detection system 18.
  • the detected light from the flame is focused on the photocell 78 to produce an electrical signal in response to a selected characteristic of the flame.
  • the signal controls the meter 80 to provide an accurate analytical measurement of the selected characteristic.
  • the perforated screen 57 or other wetting surface on the inside of the barrel is effective to collect the droplets and facilitate their downward flow toward the outlet 62.
  • the baille plate 60 provides a protective channel for the downwardly flowing droplets and also helps to collect any large unatomized droplets which issue from the nozzle 52. With this arrangement, the adverse effect of the droplets on the flame, and the necessity for frequent cleaning of the grids are eliminated.
  • the sample container comprises a glass funnel which is provided with a drain outlet 85.
  • the outlet 85 includes a bent portion 86 which extends to a level above the lower end of the sample tube S0.
  • the sample within the coni tainer and the outlet is in liquid form or in solution and may include an internal standard.
  • the normal level of the liquid in the bent portion 86 is shown schematically in FIG. 2 by the dash line 87.
  • the added liquid raises the level within the bent portion S6 'and permits the previous sample to be withdrawn automatically by the capillary action of the liquid as it moves through the bent portion and down the tail 88 of the funnel below the level of the trap 89.
  • a small quantity of the additional sample is then added in the container to provide further insurance that the liquid drawn into the tube 50 is an accurate repre sentation of the sample being evaluated.
  • the inner grid 67 is effective to smooth out and stabilize the flow to the upper grid 68. As a result, an extremely steady flame is produced on the upper grid 68.
  • Each grid is fabricated from a thin perforated plate, thus avoiding l-ong channels in the grid which exhibit a tendency to collect sample residue and require frequent cleaning.
  • An analytical instrument comprising, in combination:
  • a light sensitive detection system responsive to a characteristic of said flame for making an analytical measurement of said characteristic
  • venturi means in fluid flow communication with said atomizing means, said venturi means having a venturi passage and a control passage for regulating fluid flow through the venturi passage;
  • An analytical instrument comprising, in combination:
  • a light sensitive detection system responsive to Ia characteristic of said flame for making an analytical measurement of said characteristic
  • venturi means in fluid flow communication with said atomizing means
  • venturi means for supplying 'fuel gas to said venturi means
  • venturi means for supplying combustion supporting gas to said venturi means, said venturi means mixing Said combustion supporting gas with said fuel gas and maintaining the mixture ratio of said combustion supporting gas and said fuel gas substantially constant irrespective of pressure fluctuations in the fuel gas supply.
  • An analytical instrument comprising, in combination:
  • barrel means interconnecting said atomizing means and said burner, the atomized sample being directed through the barrel means from said atomizing means to said llame;
  • a light sensitive detection system responsive to a characteristic of said flame for making an analytical measurement of said characteristic
  • venturi means in fluid flow communication with said atomizing means
  • venturi means for supplying pressurized gas to said venturi means, said pressurized gas exhibiting a drop in pressure as it passes through said venturi means, said venturi means drawing said fuel gas through said venturi means at a rate substantially controlled by said drop in pressure.
  • barrel means interconnecting said atomizing means and said burner, the atomized sample being directed through the barrel means from said atomizing means to said flame;
  • venturi means in ⁇ uid flow communication with said atomizing means, said venturi means having a venturi passage and a control passage for regulating uid ow through the venturi passage;
  • housing means including an atomizing nozzle and a drain outlet
  • a ⁇ burner in spaced juxtaposition with the housing means for producing a ame
  • barrel means interconnecting said housing means and said burner, the atomized sample being directed through the barrel means from said atomizing nozzle to said flame;
  • venturi means mounted within said housing means
  • venturi means having a venturi passage and a control passage for regulating uid flow through the venturi passage;
  • said housing means including a plurality of passages for dividing said combustion supporting gas into separate streams, one of said streams being supplied to the control passage of said venturi means and the other stream being supplied to said atomizing nozzle to atomize said sample.
  • An analytical instrument comprising, in combination:
  • housing means including an atomizing nozzle and a drain outlet
  • a burner in spaced juxtaposition with the housing means for producing a flame
  • barrel means interconnecting said housing means and said burner, the atomized sample being directed through the barrel means from said atomizing nozzle to said flame, a portion of said atomized sample tending to form undesired droplets of sample material within said barrel means;
  • a light sensitive detection system responsive to a characteristic of said flame for making an analytical measurement of said Characteristic
  • venturi means communicating with said housing means, said Venturi means having a venturi passage and a control passage for regulating fluid flow through the venturi passage;
  • An analytical instrument comprising, in combination:
  • housing means including an atomizing nozzle and a drain outlet
  • barrel means interconnecting said housing means and said burner, the atomized sample passing through said barrel means to said flame, said barrel means including an elongated tube having a rst portion extending at an angle with respect to the horizontal and a second portion which is angularly disposed relative to said first portion, the sample within said barrel means tending to form undesired droplets of sample material in the rst portion of said tube;
  • a light sensitive detection system responsive to a characteristic of said flame for making an analytical measurement of said characteristic
  • venturi means mounted within said housing means and having a fuel gas outlet leading to said barrel means, said fuel gas outlet being spaced apart from said drain outlet;
  • venturi means for supplying fuel gas to said venturi means
  • a first grid mounted in the path of the mixture of fuel gas and atomized sample for smoothing the flow of said mixture toward said flame;
  • a second grid carried by said burner for supporting said flame.
  • a burner in juxtaposition with the atomizing means for producing a llame; barrel means interconnecting said atomizing means and said burner, the atomized sample being directed said container including an outlet having a trap through the barrel means from said atomizing means portion, a bent portion and a discharge end at a to said llame, said barrel means comprising two level below said trap portion; sections which meet at an angle; housing means including an atomizing nozzle; a light sensitive detection system responsive to a charconduit means for transmitting sample from the conacteristic of said llame for making an analytical tainer to said housing means, said conduit means measurement of said characteristic; having an end disposed within said container at a venturi means communicating with said atomizing level below the bent portion of the container outlet means; for receiving said sample, the received sample being means for supplying fuel gas to said venturi means; directed by said conduit means to said housing means and and atomized by said atomizing nozzle; l5 means for supplying pressurized gas to said venturi
  • said barrel means comprising two 19.
  • An analytical instrument comprising, in combination:
  • said container including an outlet having a trap portion and a discharge end at a level below said trap portion;

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  • Health & Medical Sciences (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
  • Sampling And Sample Adjustment (AREA)
US775985A 1968-10-09 1968-10-09 Analytical instrument Expired - Lifetime US3592608A (en)

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US77598568A 1968-10-09 1968-10-09

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US (1) US3592608A (enrdf_load_stackoverflow)
DE (1) DE1950989B2 (enrdf_load_stackoverflow)
GB (1) GB1250943A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4957896A (enrdf_load_stackoverflow) * 1972-06-07 1974-06-05
US5033850A (en) * 1990-03-28 1991-07-23 Pennington Hurm D Gas flow chamber for use in atomic absorption and plasma spectroscopy
US5186621A (en) * 1990-03-28 1993-02-16 The Texas A & M University System Chimney holder and injection tube mount for use in atomic absorption and plasma spectroscopy
US20030003590A1 (en) * 2001-06-28 2003-01-02 Abbasi Hamid A. Method for measuring concentrations of gases and vapors using controlled flames

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0021575A1 (en) * 1979-05-16 1981-01-07 Imperial Chemical Industries Plc Method, apparatus and use for nebulisation of liquids
DE3233130A1 (de) * 1982-09-07 1984-03-08 Harald Dipl.-Chem. Dr. 4600 Dortmund Berndt Verfahren zum einbringen einer probensubstanz in feiner verteilung in eine anregungsquelle fuer spektroskopische zwecke
DE3521529A1 (de) * 1985-06-15 1987-01-02 Harald Dipl Chem Dr Berndt Vorrichtung zum zerstaeuben von probenfluessigkeit fuer spektroskopische zwecke
DE8911331U1 (de) * 1989-09-22 1989-11-02 Bergner, Helmut, 2000 Hamburg Matte für den Fußraum von Kraftfahrzeugen

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4957896A (enrdf_load_stackoverflow) * 1972-06-07 1974-06-05
US5033850A (en) * 1990-03-28 1991-07-23 Pennington Hurm D Gas flow chamber for use in atomic absorption and plasma spectroscopy
US5186621A (en) * 1990-03-28 1993-02-16 The Texas A & M University System Chimney holder and injection tube mount for use in atomic absorption and plasma spectroscopy
US20030003590A1 (en) * 2001-06-28 2003-01-02 Abbasi Hamid A. Method for measuring concentrations of gases and vapors using controlled flames
US6780378B2 (en) * 2001-06-28 2004-08-24 Gas Technology Institute Method for measuring concentrations of gases and vapors using controlled flames

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Publication number Publication date
DE1950989A1 (de) 1970-04-16
GB1250943A (enrdf_load_stackoverflow) 1971-10-27
DE1950989B2 (de) 1974-01-24

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