MULTI-SPECTRAL INFRARED IMAGING SYSTEM FOR FLARE COMBUSTION EFFICIENCY MONITORING

• US 20130342680A1
• Filed: 03/26/2013
• Published: 12/26/2013
• Est. Priority Date: 06/21/2012
• Status: Active Grant

• Current Assignee: Providence Photonics, LLC (Metwood, Inc.)
• Original Assignee: Providence Photonics, LLC (Metwood, Inc.)
• Inventors: Zeng, Yousheng, Morris, Jon, Dombrowski, Mark
• Granted Patent: US 9,258,495 B2
• Time in Patent Office: Days
• US Class Current: 348/135
• CPC Class Codes: G01J 2005/0077 Imaging
• CPC Class Codes: G01J 5/0014 for sensing the radiation from gases, flames
• CPC Class Codes: G01J 5/0806 Focusing or collimating elements, e.g. lenses or concave mirrors
• CPC Class Codes: H04N 23/11 for generating image signals from visible and infrared light wavelengths

Abstract

The multi-spectral imaging system for real-time measurement of combustion efficiency of an industrial flare is provided. The system includes four spectral bands, one for a hydrocarbon group (fuel), one for carbon dioxide (CO₂), product of complete combustion), one for carbon monoxide (CO, product of partially completed combustion), and one for background reference. More spectral bands can be added to measure combustion efficiency of specific compounds or enhance the background reference adjustment. The analysis apparatus includes a machine readable storage medium, which provides instructions that cause the analysis apparatus to perform operations to obtain the combustion efficiency of the flare. The operations includes acquiring at least three spatially and temporally synchronized intensities from an imaging unit capturing images of the flare, and producing the combustion efficiency of the flare from said at least three intensities, and absorption coefficients of materials contained in the flare.

Claims

1. A multi-spectral imaging system for measurement of combustion efficiency of a flare, comprising:

an imaging unit capturing images of the flare, the imaging unit producing at least three spatially and temporally synchronized intensities from the images of the flare, a first intensity of said at least three intensities representing an amount of a first material contained in the flare, a second intensity of said at least three intensities representing an amount of a second material contained in the flare, a third intensity of said at least three intensities representing an amount of a third material contained in the flare, the first material including fuel, the second material including carbon dioxide; and

an analysis apparatus coupled to the imaging unit, the analysis apparatus including a machine readable storage medium which provides instructions that cause the analysis apparatus to perform operations to obtain the combustion efficiency of the flare, the operations comprising;

acquiring said at least three intensities from the imaging unit;

retrieving a first absorption coefficient, a second absorption coefficient and a third absorption coefficient, which are stored in the machine readable storage medium, the first absorption coefficient being an absorption coefficient of the first material, the second absorption coefficient being an absorption coefficient of the second material, the third absorption coefficient being an absorption coefficient of the third material;

retrieving a weighted average carbon number of the fuel, which is stored in the machine readable storage medium; and

producing the combustion efficiency of the flare from said at least three intensities, the first absorption coefficient, the second absorption coefficient, the third absorption coefficient and the weighted average carbon number of the fuel.

2. A multi-spectral imaging system of the claim 1, comprised of the fuel including hydrocarbon, the third material including carbon monoxide.

3. A multi-spectral imaging system of the claim 1, wherein said at least three intensities includes a fourth spatially and temporally synchronized intensity that represents a reference intensity, said producing the combustion efficiency of the flare comprising producing the combustion efficiency of the flare from said at least three intensities including the fourth intensity, the first absorption coefficient, the second absorption coefficient, the third absorption coefficient, and the weighted average carbon number of the fuel.

4. A multi-spectral imaging system of the claim 3, comprised of said producing the combustion efficiency of the flare including calculating the combustion efficiency from a formula

5. A multi-spectral imaging system of the claim 4, comprised of the producing the combustion efficiency of the flare further comprising:

calculating water vapor absorption correction factors from a formula

6. A multi-spectral imaging system of the claim 3, comprised of the producing the combustion efficiency of the flare including calculating the combustion efficiency from a formula

7. A multi-spectral imaging system of the claim 6, comprised of the producing the combustion efficiency of the flare further comprising:

measuring the temperature T_g of the flare; and

retrieving the black body radiations of the first material B(T_g, λ

₁), the black body radiation of the second material B(T_g, λ

₂), and the black body radiation of the third material B(T_g, λ

₃), which are stored in the machine readable storage medium.

8. A multi-spectral imaging system of the claim 6, comprised of the producing the combustion efficiency of the flare further comprising:

calculating water vapor absorption correction factors from a formula

9. A multi-spectral imaging system of the claim 3, comprised of the imaging unit comprising:

an objective lens;

a detector array including a plurality of detectors, each of the detectors including a plurality of sub-detectors, the detector array detecting intensities from the images of the flare;

a micro-lens array disposed between the objective lens and the detector array, the micro-lens array including a plurality of micro-lenses;

a bandpass filter array disposed between the micro-lens array and the detector array, the bandpass filter array including a plurality of bandpass filters, each of the bandpass filters including a plurality of sub-filters, the sub-filters having different wavelength bandpass windows from each other, the images of the flare passing through one of the micro-lenses being transmitted to one of the bandpass filters and being detected by one of the detectors.

10. A multi-spectral imaging system of the claim 9, wherein the first intensity is an intensity of the images of the flare passing through a first one of the sub-filters, the second intensity is an intensity of the images of the flare passing through a second one of the sub-filters, the third intensity is an intensity of the images of the flare passing through a third one of the sub-filters, and the fourth intensity is an intensity of the images of the flare passing through a fourth one of the sub-filters.

11. A multi-spectral imaging system of the claim 10, comprised of the first one of the sub-filters having a wavelength bandpass window of absorption of the fuel.

12. A multi-spectral imaging system of the claim 11, wherein the wavelength bandpass window of the first one of the sub-filters includes a wavelength range between 3.3 μ

m and 3.4 μ

m.

13. A multi-spectral imaging system of the claim 10, comprised of the second one of the sub-filters having a wavelength bandpass window of absorption of carbon dioxide.

14. A multi-spectral imaging system of the claim 13, wherein the wavelength bandpass window of the second one of the sub-filters includes a wavelength range between 4.2 μ

m and 4.3 μ

m.

15. A multi-spectral imaging system of the claim 10, comprised of the third one of the sub-filters having a wavelength bandpass window of absorption of carbon monoxide.

16. A multi-spectral imaging system of the claim 15, wherein the wavelength bandpass window of the third one of the sub-filters includes a wavelength range between 4.7 μ

m and 4.8 μ

m.

17. A machine readable storage medium, which provides instructions that cause a machine apparatus to perform operations to obtain combustion efficiency of a flare, the operations comprising:

acquiring at least three spatially and temporally synchronized intensities from an imaging unit capturing images of the flare, a first intensity of said at least three intensities representing an amount of a first material contained in the flare, a second intensity of said at least three intensities representing an amount of a second material contained in the flare, a third intensity of said at least three intensities representing an amount of a third material contained in the flare, the first material including fuel, the second material including carbon dioxide;

retrieving a first absorption coefficient, a second absorption coefficient and a third absorption coefficient, which are stored in the machine readable storage medium, the first absorption coefficient being an absorption coefficient of the first material, the second absorption coefficient being an absorption coefficient of the second material, the third absorption coefficient being an absorption coefficient of the third material;

retrieving a weighted average carbon number of the fuel, which is stored in the machine readable storage medium; and

producing the combustion efficiency of the flare from said at least three intensities, the first absorption coefficient, the second absorption coefficient, the third absorption coefficient and the weighted average carbon number of the fuel.

18. The machine readable storage medium of the claim 17, comprised of the fuel including hydrocarbon, the third material including carbon monoxide.

19. The machine readable storage medium of the claim 17, wherein said at least three intensities includes a fourth intensity that represents a reference intensity, said producing the combustion efficiency of the flare comprising producing the combustion efficiency of the flare from said at least three intensities including the fourth intensity, the first absorption coefficient, the second absorption coefficient, the third absorption coefficient, and the weighted average carbon number of the fuel.

20. The machine readable storage medium of the claim 19, comprised of said producing the combustion efficiency of the flare including calculating the combustion efficiency from a formula

21. A multi-spectral imaging system of the claim 20, comprised of the producing the combustion efficiency of the flare further comprising:

calculating water vapor absorption correction factors from a formula

22. The machine readable storage medium of the claim 19, comprised of the producing the combustion efficiency of the flare including calculating the combustion efficiency from a formula

23. A multi-spectral imaging system of the claim 22, comprised of the producing the combustion efficiency of the flare further comprising:

measuring the temperature Tg of the flare; and

retrieving the black body radiations of the first material B(T_g, λ

₁), the black body radiation of the second material B(T_g, λ

₂), and the black body radiation of the third material B(T_g, λ

₃), which are stored in the machine readable storage medium.

24. A multi-spectral imaging system of the claim 22, comprised of the producing the combustion efficiency of the flare further comprising:

calculating water vapor absorption correction factors from a formula