Spectrometer gas analyzer system

• US 5,739,038 A
• Filed: 07/26/1996
• Issued: 04/14/1998
• Est. Priority Date: 07/26/1996
• Status: Expired due to Fees

• Current Assignee: Forney Corporation (Graham Holdings Company)
• Original Assignee: Anarad, Inc. (Leonardo S.p.A.)
• Inventors: Burrows, Donald Edward
• Primary Examiner(s): Soderquist, Arlen
• Application Number:
  US08/686,827
• Time in Patent Office: 627 Days
• Field of Search: 436/113, 436/116, 436/117, 436/118, 436/119, 436/120, 436/121, 436/122, 436/155, 436/158, 436/164, 436/171, 422/83, 422/91, 422/93, 422/174, 422/199
• US Class Current: 436/113
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: Y10T 436/175383 Ammonia
• CPC Class Codes: Y10T 436/177692 Oxides of nitrogen
• CPC Class Codes: Y10T 436/178459 Only nitrogen dioxide
• CPC Class Codes: Y10T 436/179228 Both nitrogen oxide and dioxide
• CPC Class Codes: Y10T 436/18 Sulfur containing
• CPC Class Codes: Y10T 436/182 Organic or sulfhydryl containing [e.g., mercaptan, hydrogen, sulfide, etc.]
• CPC Class Codes: Y10T 436/184 Only hydrogen sulfide
• CPC Class Codes: Y10T 436/186 Sulfur dioxide

Abstract

A gas analyzer system for providing a spectroscopic analysis of the sample gas. This analysis is accomplished by first introducing the sample gas into the inlet of the system and transporting it to a spectral analyzer. The sample gas is then spectrally analyzed and the analyzer outputs a signal indicative of a radiation intensity spectrum associated with the analyzed sample gas. A processing unit uses the analyzer signal to detect the presence of one or more prescribed gases and to determine the concentration of each of the prescribed gases in the sample gas. Next, the reacting agent is supplied to the sample gas to convert one or more gases whose presence in the sample gas cannot be detected via spectral analysis due to the masking effects other gases present in the sample gas. The masked gases are converted to secondary gases at least one of which is readily detectable via spectral analysis. This converting process occurs in the time it takes for the sample gas to transit uninterrupted through the system to the analyzer. The modified sample gas is spectrally analyzed, and the processing unit detects the presence of the masked gases and determines the concentration of each. The system may be employed to monitor certain environmental gases contained within industrial emission. In such a case, the prescribed gases are nitrogen dioxide and sulfur dioxide, and the masked gases are nitric oxide, ammonia, and hydrogen sulfide.

Claims

1. A gas analyzer system, comprising:

a sample gas inlet for introducing a sample gas which is to be analyzed;

a first mixer having a first inlet into which the sample gas can be fed and an outlet;

a first mixer supply containing an oxidant gas connected to a second inlet of the first mixer so as to supply the oxidant gas thereto, said oxidant gas capable of being supplied to the first mixer in a sufficient quantity to convert substantially all of a quantity of nitric oxide (NO) present in the sample gas to a gas comprising a quantity of nitrogen dioxide (NO₂), said conversion taking place in the time it takes for the sample gas to flow through the first mixer;

an ammonia reactor disposed between the sample gas inlet and the first mixer, said ammonia reactor being capable of converting gaseous ammonia to a gas comprising a quantity of nitric oxide in the time it takes for the sample gas to flow through the ammonia reactor;

a second mixer having a first inlet into which the sample gas can be fed and an outlet, said second mixer being employed to convert substantially all of a quantity of hydrogen sulfide (H₂ S) present in the sample gas to sulfur dioxide (SO₂) in the time it takes for the sample gas to flow through the second mixer;

an inlet distribution node having a first inlet connected to the sample gas inlet, a first outlet connected to an inlet of the ammonia reactor, and a second outlet connected to the first inlet of the second mixer, said inlet distribution node being capable of exclusively routing the sample gas to either the ammonia reactor or the second mixer;

a processing unit capable of controlling the inlet distribution node so as to cause the node to route the sample gas to either the ammonia reactor or the second mixer; and

a spectral analyzer having an inlet connected to the first mixer outlet and the second mixer outlet, and into which the sample gas is capable of being fed, said spectral analyzer further being capable of outputting a signal indicative of a radiation intensity spectrum over a range of wavelengths associated with the sample gas;

a pump having an inlet connected to an outlet of the spectral analyzer, said pump being capable of transporting the sample gas through the gas analyzer system.

2. The system of claim 1, wherein the ammonia reactor comprises:

a housing having a longitudinal chamber;

an inlet on one end of the chamber and an outlet on the other end of the chamber; and

means for heating gases flowing through the longitudinal chamber.

3. The system of claim 2, wherein the heating means of the ammonia reactor comprises one of (i) a heating probe extending into the longitudinal chamber from an internal wall of the housing, and (ii) a heating coil wrapped around the longitudinal chamber over at least a portion of its length.

4. The system of claim 2, wherein the heating means of the ammonia reactor is capable of heating gases flowing through the longitudinal chamber to a temperature exceeding about 1000 degrees Fahrenheit.

5. The system of claim 1 further comprising a second mixer supply containing an oxidant gas connected to a second inlet of the second mixer so as to supply oxidant gas thereto, said oxidant gas being supplied to the mixer in a sufficient quantity to facilitate said conversion of substantially all of a quantity of hydrogen sulfide (H₂ S) present in the sample gas to sulfur dioxide (SO₂) in the time it takes for the sample gas to flow through the second mixer.

6. The system of claim 5 wherein the oxidant gas supplied to the second mixer is oxygen.

7. The system of claim 1 wherein the second mixer is capable of heating gases flowing therethrough to a temperature exceeding approximately 1000 degrees Fahrenheit.

8. The system of claim 1, wherein said processing unit is further capable of detecting the presence and determining the concentration of nitrogen dioxide, nitric oxide, ammonia, sulfur dioxide, and hydrogen sulfide gases in the sample gas from the signal output by the spectral analyzer.

9. The system of claim 1, further comprising a calibration unit connected to a second inlet of the inlet distribution node, said calibration unit being capable of supplying a plurality of different calibration gases to the inlet distribution node and wherein said inlet distribution node is capable of exclusively routing the calibration gases to either the ammonia reactor or the second mixer.

10. The system of claim 9 wherein the calibration unit further comprises:

a plurality of gas supplies each containing one of said plurality of calibration gases; and

a calibration unit distribution node having a plurality of inlets each of which is connected to one of the plurality of gas supplies, and an outlet connected to the second inlet of the inlet distribution node, said calibration unit distribution node being capable of exclusively routing each one of the calibration gases to the inlet distribution node.

11. The system of claim 10 wherein said processing unit is further capable of controlling the calibration unit distribution node so as to cause the calibration unit distribution node to route the calibration gases to the inlet distribution node, and to cause the inlet distribution node to route one of the sample gas or the calibration gases to either the ammonia reactor or the second mixer.

12. The system of claim 9 wherein said plurality of calibration gases comprises a zero gas and at least one gas having a predetermined concentration of a single environmental gas, said environmental gas being one of (i) nitrogen dioxide, (ii) nitric oxide, (iii) ammonia, (iv) sulfur dioxide, and (v) hydrogen sulfide.

13. The system of claim 12 wherein the concentration of the environmental gas in the calibration gas is approximately the maximum concentration of that environmental gas expected to be present in the sample gas.

14. The system of claim 1 wherein the oxidant gas supplied to the first mixer is ozone.

15. The system of claim 14, wherein the ozone is capable of causing damage to the pump, and wherein the system further comprises an ozone killer capable of converting the ozone to gases which will not damage the pump, said ozone killer being connected between the spectral analyzer and the pump.

16. The system of claim 15, wherein the ozone killer comprises:

a housing having a longitudinal chamber;

an inlet on one end of the chamber and an outlet on the other end of the chamber; and

means for heating gases flowing through the longitudinal chamber.

17. The system of claim 16 wherein the heating means of the ozone killer comprises one of (i) a heating probe extending into the longitudinal chamber from an internal wall of the housing, and (ii) a heating coil wrapped around the longitudinal chamber over at least a portion of its length.

18. The system of claim 16 wherein the heating means of the ozone killer is capable of heating gases flowing through the longitudinal chamber to a temperature exceeding about 600 degrees Fahrenheit.

19. The system of claim 1, further comprising a pressure sensor capable of sensing the absolute pressure within a sample chamber of the spectral analyzer and outputting a signal indicative of the absolute pressure to a processing unit.

20. The system of claim 1, further comprising a temperature sensor capable of sensing the temperature of gases within a sample chamber of the spectral analyzer and outputting a signal indicative of the temperature to a processing unit.

21. The system of claim 1, wherein the spectral analyzer is a diode-array spectrophotometer.

22. A gas reactor, comprising:

a housing comprising a hollow cylindrical body section constructed of quartz forming a longitudinal chamber within;

an inlet on one end of the chamber and an outlet on the other end of the chamber, wherein the inlet comprises a graphite ferule with through hole to allow passage of gas therethrough and the outlet comprises a graphite ferule with through hole to allow passage of gas therethrough; and

means for heating gases flowing through the Iongitudinal chamber.

23. The gas reactor of claim 22, wherein the heating means of the gas reactor comprises one of (i) a heating probe extending into the longitudinal chamber from an internal wall of the housing, and (ii) a heating coil wrapped around the longitudinal chamber over at least a portion of its length.

24. The gas reactor of claim 23 wherein the heating probe comprises a ceramic material.

25. The gas reactor of claim 23 wherein the heating probe comprises an inner portion, and an outer portion which encases the inner portion, and wherein the outer portion comprises a ceramic material.

26. The gas reactor of claim 22 wherein:

the heating means of the gas reactor is capable of heating gases flowing through the longitudinal chamber to a temperature exceeding about 600 degrees Fahrenheit; and

the gas reactor is an ozone killer capable of converting ozone present in a gas flowing through the longitudinal chamber to a gas comprising oxygen, said conversion of the ozone resulting from heating the gas flowing through the chamber to a temperature exceeding about 600 degrees Fahrenheit.

27. The gas reactor of claim 22 wherein:

the heating means of the gas reactor is capable of heating gases flowing through the longitudinal chamber to a temperature exceeding about 1000 degrees Fahrenheit; and

the gas reactor is an ammonia reactor capable of converting ammonia present in a gas flowing through the longitudinal chamber to a gas comprising nitric oxide, said conversion of the ammonia resulting from heating the gas flowing through the chamber to a temperature exceeding about 1000 degrees Fahrenheit.

28. A method of spectroscopic gas analysis, comprising the steps of:

introducing a sample gas for analysis into a sample gas inlet of a spectroscopic gas analyzer system;

feeding the sample gas from the sample gas inlet into one of (i) an ammonia reactor to convert gaseous ammonia to a gas comprising a quantity of nitric oxide in the time it takes for the sample gas to flow through the ammonia reactor, or (ii) a first mixer to convert substantially all of a quantity of hydrogen sulfide (H₂ S) present in the sample gas to sulfur dioxide (SO₂) in the time it takes for the sample gas to flow through the first mixer;

whenever the sample gas is fed into the ammonia reactor, feeding it thereafter into a second mixer and simultaneously supplying an oxidant gas to the second mixer, said oxidant gas being supplied to the second mixer in a sufficient quantity to convert substantially all of a quantity of nitric oxide (NO) present in the sample gas to a gas comprising a quantity of nitrogen dioxide (NO₂), said conversion taking place in the time it takes for the sample gas to flow through the second mixer;

feeding sample gas from the first mixer and sample gas from the second mixer to the spectral analyzer, said spectral analyzer outputting a signal indicative of a radiation intensity spectrum over a range of wavelengths associated with the sample gas.

29. The method of claim 28 further comprising the step of whenever the sample gas is fed into the first mixer, simultaneously supplying an oxidant gas to the first mixer, said oxidant gas being supplied to the first mixer in a sufficient quantity to facilitate said conversion of substantially all of a quantity of hydrogen sulfide (H₂ S) present in the sample gas to sulfur dioxide (SO₂) in the time it takes for the sample gas to flow through the first mixer.

30. The method of claim 28, further comprising the step of detecting the presence and determining the concentration of nitrogen dioxide, nitric oxide, ammonia, sulfur dioxide, and hydrogen sulfide gases in the sample gas from the signal output by the spectral analyzer.

31. The method of claim 28, wherein the oxidant gas supplied to the second mixer is ozone which is capable of causing damage to a pump employed to fed the sample gas through the spectroscopic gas analyzer system, said method further comprising the step of converting the ozone to gases which will not damage the pump prior to the sample gas reaching the pump.