Specialty gas analysis system

• US 6,748,334 B1
• Filed: 12/06/2000
• Issued: 06/08/2004
• Est. Priority Date: 12/06/1999
• Status: Expired due to Fees

• Current Assignee: Jorge E. Perez, Richard T. Meyer
• Original Assignee: CIC Photonics, Inc.
• Inventors: Meyer, Richard T., Perez, Jorge E.
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): PRETLOW, DEMETRIUS R
• Application Number:
  US09/731,550
• Time in Patent Office: 1,280 Days
• Field of Search: 702/24, 702/23, 702/22, 702/31, 7 2/32, 7 2/336, 7 2/337, 250/339.03, 250/339.08, 250/339.11, 250/339.13, 250/339.12
• US Class Current: 702/24
• CPC Class Codes: G01N 2021/3595 using FTIR
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis
• CPC Class Codes: G01N 33/0016 by regulating a physical variable, e.g. pressure, temperature

Abstract

A system and method for detection of impurities in gases comprising a Fourier transform infrared spectrometer and computation devices for system control, spectral analysis, and chemometrics.

Claims

1. A system for detection of impurities in gases, the system comprising:

a Fourier transform infrared spectrometer; and

means for computation comprising;

means for system control computation;

means for spectral analysis computation; and

means for chemometrics computation employing a running average of estimated impurity levels from a plurality of scans; and

wherein said system control computation means and said spectral analysis computation means reduce spectrometer drift and perturbations from molecular background absorption by alternating scans between background spectra and sample spectra, which in conjuction with said chemometrics computation means increases signal-to-noise ratio.

2. The system of claim 1 additionally comprising a detector operating at approximately room temperature, said system having a limit of detection of gas impurities of between approximately 10-25 ppb/v.

3. The system of claim 1 wherein said system control computation means comprises gas flow control means controlling gas flow through a gas manifold.

4. The system of claim 1 wherein said system control computation means comprises temperature control means for control of moisture buildup.

5. The system of claim 1 wherein said system control computation means comprises means for adjusting a transfer mirror.

6. The system of claim 1 wherein said chemometrics computation means computes an average concentration of an impurity at every scan.

7. The system of claim 6 wherein said chemometrics computation means is responsive to changes in impurity concentrations occurring from both scan to scan and over said plurality of scans.

8. The system of claim 1 wherein said chemometrics computation means assumes that a system baseline is not necessarily centered around an x-axis of collected spectra so as to reduce errors resulting from baseline drift.

10. The method of claim 1 additionally comprising employing a detector operating at approximately room temperature and establishing a limit of detection of gas impurities of between approximately 10-25 ppb/v.

9. A method for detection of impurities in gases, the method comprising the steps of:

providing a Fourier transform infrared spectrometer; and

employing a means for computation comprising;

employing means for system control computation;

performing spectral analysis using means for spectral analysis computation; and

performing chemometrics analysis employing a running average of estimated impurity levels from a plurality of scans using means for chemometrics computation; and

wherein employing system control computation means and performing spectral analysis comprise reducing spectrometer drift and perturbations from molecular background absorption by alternating scans between background spectra and sample spectra, which in conjunction with the chemometrics analysis step increases signal-to-noise ratio.

11. The method of claim 9 wherein employing system control computation means comprises controlling gas flow through a gas manifold using gas flow control means.

12. The method of claim 9 wherein employing system control computation means comprises controlling moisture buildup employing temperature control means.

13. The method of claim 9 wherein employing system control computation means comprises adjusting a transfer mirror.

14. The method of claim 9 wherein performing chemometrics analysis comprises computing an average concentration of an impurity at every scan.

15. The method of claim 14 wherein performing chemometrics analysis comprises reporting changes in impurity concentrations occurring from both scan to scan and over the plurality of scans.

16. The method of claim 9 wherein the step of performing the chemometrics analysis assumes that a system baseline is not necessarily centered around an x-axis of collected spectra so as to reduce errors resulting from baseline drift.

17. A system for detection of impurities in gases, the system comprising:

a Fourier transform infrared spectrometer;

means for computation comprising;

means for system control computation;

means for spectral analysis computation; and

means for chemometrics computation employing a running average of estimated impurity levels from a plurality of scans; and

a detector operating at approximately room temperature, said system having a limit of detection of gas impurities of between approximately 10-25 ppb/v.

18. A system for detection of impurities in gases, the system comprising:

a Fourier transform infrared spectrometer; and

means for computation comprising;

means for system control computation;

means for spectral analysis computation; and

means for chemometrics computation employing a running average of estimated impurity levels from a plurality of scans; and

wherein said system control computation means comprises temperature control means for control of moisture buildup.

19. A system for detection of impurities in gases, the system comprising:

a Fourier transform infrared spectrometer; and

means for computation comprising;

means for system control computation;

means for spectral analysis computation; and

means for chemometrics computation employing a running average of estimated impurity levels from a plurality of scans; and

wherein said chemometrics computation means computes an average concentration of an impurity at every scan.

20. A method for detection of impurities in gases, the method comprising the steps of:

providing a Fourier transform infrared spectrometer;

employing a means for computation comprising;

employing means for system control computation;

performing spectral analysis using means for spectral analysis computation; and

performing chemometrics analysis employing a running average of estimated impurity levels from a plurality of scans using means for chemometrics computation; and

employing a detector operating at approximately room temperature and establishing a limit of detection of gas impurities of between approximately 10-25 ppb/v.

21. A method for detection of impurities in gases, the method comprising the steps of:

providing a Fourier transform infrared spectrometer; and

employing a means for computation comprising;

employing means for system control computation;

performing spectral analysis using means for spectral analysis computation; and

performing chemometrics analysis employing a running average of estimated impurity levels from a plurality of scans using means for chemometrics computation; and

wherein employing system control computation means comprises controlling moisture buildup employing temperature control means.

22. A method for detection of impurities in gases, the method comprising the steps of:

providing a Fourier transform infrared spectrometer; and

employing a means for computation comprising;

employing means for system control computation;

performing spectral analysis using means for spectral analysis computation; and

performing chemometrics analysis employing a running average of estimated impurity levels from a plurality of scans using means for chemometrics computation; and

wherein performing chemometrics analysis comprises computing an average concentration of an impurity at every scan.