US3743425A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flame photometer using vibrating slit monochromator
Assignee: Shell USA Inc
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Filing: 1971-04-15
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Granted: 1973-07-03
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Expires: 1991-04-15
Abstract
Abstract A flame photometer for use in monitoring processes wherein the fuel gas and/or sample produce a high background emission spectrum and a monochromator for detecting the signal of interest with the background being removed by filtering the signal with a vibrating slit in the monochromator. The system also includes a means for automatic standardization of the recorded signal.
Inventors
- 👤 J Jobe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 14:22
CPC Classifications
G; G01; G01J; G01J3/00; G01J3/28; G01J3/42; G01J3/433; G01N; G01N21/00; G01N21/62; G01N21/71; G01N21/72
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
172 words
An apparatus for detecting the quantity of a metallic element in a process stream, said apparatus comprising: a burner assembly including means for supplying a fuel gas, air and a sample of the process stream thereto; a monochromator disposed to intercept the light emitted by the flame, said monochromator having a narrow fixed entrance opening and means for producing a spectrum of the light passing through the entrance opening; a narrow exit slit opening disposed to pass a narrow band of light from said spectrum, a drive means coupled to said exit slit opening and disposed to vibrate said exit opening at a predetermined frequency; light detecting means comprising means for detecting the modulation of the light from said vibrating exit slit at the fundamental frequency of vibration of said slit and at twice the fundamental frequency of said slit and converting a signal representing twice the fundamental frequency to a related electrical signal; and recording means coupled to said light detecting means to record said electrical signal in relation to time.
Claim 2
Independent Claim
172 words
An apparatus for detecting the quantity of a metallic element in a process stream, said apparatus comprising: a burner assembly including means for supplying a fuel gas, air and a sample of the process stream thereto; a monochromator disposed to intercept the light emitted by the flame, said monochromator having a narrow fixed entrance opening and means for producing a spectrum of the light passing through the entrance opening; a narrow exit slit opening disposed to pass a narrow band of light from said spectrum, a drive means coupled to said exit slit opening and disposed to vibrate said exit opening at a predetermined frequency; light detecting means comprising means for detecting the modulation of the light from said vibrating exit slit at the fundamental frequency of vibration of said slit and at twice the fundamental frequency of said slit and converting a signal representing twice the fundamental frequency to a related electrical signal; and recording means coupled to said light detecting means to record said electrical signal in relation to time.
Claim 3
Dependent Claim
36 words
The apparatus of claim 1, and in addition an autoranging means for adjusting the range of the recording means in response to the introduction into the burner of a sample having known amounts of metallic elements.
Claim 4
Dependent Claim
12 words
The apparatus of claim 1 wherein said fuel gas is a hydrocarbon.
Claim 5
Dependent Claim
54 words
The apparatus of claim 1 wherein said exit slit opening comprises a vane member mounted on said drive means for movement in a plane disposed at right angles to the beam of light from the spectrum producing means, said vane having a narrow elongated slit formed therein for passing said narrow band of light.
Claim 6
Dependent Claim
45 words
The apparatus of claim 2 wherein said autoranging means comprises circuit means for injecting into the burner a standard sample having a known composition and a means for adjusting the recorder to a predetermined scale reading in response to the injection of the standard sample.
Claim 7
Dependent Claim
89 words
The apparatus of claim 5 wherein said autoranging circuit includes a multiplying circuit, said light detecting means being coupled to the input of said multiplying circuit; a comparing circuit for comparing a reference signal representing the predetermined scale reading of the recorder witH the output signal of said multiplying circuit; said comparing circuit being coupled to said multiplying circuit to control said multipying circuit in response to the difference between said reference signal and the signal from said multiplier that corresponds to the signal produced by the standard sample.
Claim 8
Dependent Claim
15 words
The apparatus of claim 3 wherein the hydrocarbon gas is stored as a liquid hydrocarbon.
Claim 9
Independent Claim
180 words
A method for determining the quantity of a metallic element in a sample wherein burning of the sample produces background light having a definite slope, said method comprising the steps of: burning the sample; intercepting the light emitted by said burning; producing a spectrum of the light intercepted; scanning said spectrum with an exit slit vibrated completely across the spectral line of interest to include a first portion of the spectrum that does not include the spectral line of interest, a second portion of the spectrum that does include the spectral line of interest and a third portion of the spectrum that does not include the spectral line of interest; generating a reference signal of twice the scanning frequency of said exit slit; separating the signal produced by scanning the spectrum and the signal of twice the scanning frequency of the exit slit to reject background light which is not constant but which has a definite slope thereby passing only the signal due to the spectral line of interest; and recording the signal due to the spectral line of interest.
Claim 10
Independent Claim
180 words
A method for determining the quantity of a metallic element in a sample wherein burning of the sample produces background light having a definite slope, said method comprising the steps of: burning the sample; intercepting the light emitted by said burning; producing a spectrum of the light intercepted; scanning said spectrum with an exit slit vibrated completely across the spectral line of interest to include a first portion of the spectrum that does not include the spectral line of interest, a second portion of the spectrum that does include the spectral line of interest and a third portion of the spectrum that does not include the spectral line of interest; generating a reference signal of twice the scanning frequency of said exit slit; separating the signal produced by scanning the spectrum and the signal of twice the scanning frequency of the exit slit to reject background light which is not constant but which has a definite slope thereby passing only the signal due to the spectral line of interest; and recording the signal due to the spectral line of interest.
Claim 11
Dependent Claim
42 words
The method of claim 8 further including the step of periodically substituting a sample stream having a known concentration of the metallic element of interest for the process stream and recording the resulting signal on a scale related to the known concentration.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-02 | 1977-01-01 | 1977-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-02 | 1981-01-01 | 1981-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-02 | 1985-01-01 | 1985-07-03 | $7700.00 | Window Closed / Lapsed |