System and method for determining combustion temperature using infrared emissions

• US 6,393,375 B1
• Filed: 07/07/1999
• Issued: 05/21/2002
• Est. Priority Date: 01/15/1999
• Status: Expired due to Fees

• Current Assignee: En'Urga, Inc.
• Original Assignee: En'Urga, Inc.
• Inventors: Sivathanu, Yudaya Raju
• Primary Examiner(s): Bui, Bryan
• Application Number:
  US09/348,802
• Time in Patent Office: 1,049 Days
• Field of Search: 702/130, 702/134, 702/135, 702/189, 250/339.01, 250/339.04, 250/339.11, 250/339.14, 374/121, 374/130-134
• US Class Current: 702/135
• CPC Class Codes: G01J 5/0014 for sensing the radiation from gases, flames
• CPC Class Codes: G01J 5/041 Mountings in enclosures or in a particular environment
• CPC Class Codes: G01J 5/602 using selective, monochromatic or bandpass filtering
• CPC Class Codes: H05H 1/0043 by using infrared or ultraviolet radiation

Abstract

The present invention relates to a combustion temperature sensor, and, more particularly, to a combustion temperature sensor that measures infrared energy emitted at several preselected wavelengths from a flame and/or a flame'"'"'s hot gas at a turbine inlet location and applies the energy signals to a calculation model to yield temperature.

Claims

1. A method of determining temperature from a plurality of radiation intensity values, said method comprising the steps of:

creating a look-up table of a plurality of simulated radiation intensity values being calculated as a function of a range of temperature values and a range of molar concentration values of gas emissions;

receiving a plurality of values of input radiation intensity signals;

selecting one of said values of input radiation signals as a background radiation signal;

subtracting said background radiation signal from the remaining said plurality of values of radiation signals to obtain corrected radiation signals; and

comparing the values of said corrected radiation intensity signals with said simulated radiation intensity values and determining a temperature value from the value of said input radiation intensity signals.

2. A method as claimed in claim 1, further comprising the step of multiplying a constant factor to said background radiation signal, said constant being a fixed function of optical energy at each of said plurality of radiation signals.

3. A method as claimed in claim 1, further comprising the step of adjusting each said plurality of said radiation signals by a variable correction factor.

4. A method as claimed in claim 1, wherein each said simulated radiation intensity value comprises a discrete IR radiation intensity value as a function of temperature.

5. A method as claimed in claim 1, wherein said values of input radiation intensity signals being selected from a group of discrete IR radiation intensity values consisting of:

a first radiation intensity value corresponding to an IR emission wavelength of between 2.275 and 2.285 μ

m, inclusive;

a second radiation intensity value corresponding to an IR emission wavelength of between 2.545 and 2.575 μ

m, inclusive;

a third radiation intensity value corresponding to an IR emission wavelength of between 2.685 and 2.715 μ

m, inclusive; and

a fourth radiation intensity value corresponding to an IR emission wavelength of between 2.855 and 2.885 μ

m, inclusive.

6. A method as claimed in claim 5, wherein the second, third and fourth emission wavelengths are selected anywhere in the gas emission band of H₂O and CO₂ between 2.7 and 3.2 μ

m and between 4.3 and 4.6 μ

m or between 3.5 and 4.0 μ

m.

7. A method as claimed in claim 1, further comprising the step of formatting said look-up table into a plurality of columns, one column for each said simulated radiation intensity values at a preselected wavelength and a column of temperatures values, each row of said simulated radiation intensity values corresponding to a row in said column of temperature values.

8. A method as claimed in claim 9, further comprising the step of condensing each said column of said radiation intensity values.

9. A method as claimed in claim 1, wherein said molar concentration values comprises gas emissions of CO₂ and H₂O.

10. A method as claimed in claim 9, wherein said range molar concentration values of CO₂ are from 0 and 0.075, inclusive.

11. A method as claimed in claim 9, wherein said range molar concentration values of H₂O are from 0 and 0.15, inclusive.

12. A method as claimed in claim 1, wherein said range of temperature values are from 500°

to 1500°

C., inclusive.

13. A method as claimed in claim 1, further comprising the step of performing a sequential search operation of said table for comparing said input radiation intensity signals with said simulated radiation intensity values.

14. A method as claimed in claim 1, further comprising the step of interpolating between two simulated radiation intensity values at a given wavelength when said input radiation intensity value has a value between two sequential simulated radiation intensity values.