Temperature measurement system for furnaces

Patent metadata

Field	Value
Publication number	US-11079283-B2
Application number	US-201916364559-A
Country	US
Kind code	B2
Filing date	Mar 26, 2019
Priority date	Apr 1, 2016
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

A method for measuring furnace temperatures. The method includes obtaining radiance measurements from a plurality of regions of interest (ROIs) using a plurality of thermal imaging cameras, and measuring a surface temperature using a radiance measurement obtained from an ROI selected from the plurality of ROIs. Measuring the surface temperature includes determining an effective background radiance affecting the selected ROI using radiance measurements obtained from ROIs different from the selected ROI, obtaining a compensated radiance by removing the effective background radiance from the radiance measurement obtained from the selected ROI, and converting the compensated radiance to the measured surface temperature.

First claim

What is claimed is:

1. A method for measuring furnace temperatures, comprising:
obtaining radiance measurements from a plurality of regions of interest (ROIs) in a furnace, employing a plurality of thermal imaging cameras;
measuring a surface temperature of the furnace using a radiance measurement obtained from a ROI selected from the plurality of ROIs, including:
determining an effective background radiance affecting the selected ROI, using a weighted average of radiance measurements obtained from ROIs that are different from the selected ROI and that are in a hemisphere in front of the selected ROI;
obtaining a compensated radiance by removing the effective background radiance from the radiance measurement obtained from the selected ROI; and
converting the compensated radiance to the measured surface temperature of the furnace, wherein the radiance measurement obtained from the selected ROI is obtained from a plurality of pixels in the ROI, averaged over at least one selected from the group consisting of space and time.

2. The method of claim 1 , wherein the furnace is a steam reformer furnace and each of the plurality of ROIs is a surface region on one selected from a group consisting of a reformer tube, a wall, a floor, a ceiling and a flame front.

3. The method of claim 1 , wherein the radiance measurements are concurrently obtained; and wherein the surface temperature is measured in real-time.

4. The method of claim 1 , wherein the radiance measurements are obtained at a wavelength of incident radiation of about 850 nm or about 3.9 μm using the thermal imaging cameras.

5. The method of claim 1 , wherein the effective background radiance affecting the selected ROI is calculated from a geometric view factor-based weighted average of radiance measurement of the surfaces within a hemisphere in front of the selected ROI.

6. The method of claim 1 , wherein the selected ROI is obtained from a first camera of the plurality of cameras and the ROIs used for determining the effective background radiance for the selected ROI are obtained from one or more cameras other than the first camera.

7. The method of claim 1 , further comprising: correcting the radiance measurement obtained from the selected ROI for an emissivity of the selected ROI.

8. The method of claim 7 , wherein the emissivity is determined through comparison of the radiance measurement obtained from the selected ROI with a radiance measurement obtained from a reference body with a known emissivity and a known temperature.

9. The method of claim 7 , wherein the emissivity is determined using a reference temperature measured in the vicinity of the selected ROI utilizing a temperature sensor.

10. A method of monitoring and controlling a furnace, comprising:
obtaining radiance measurements from a plurality of region of interest (ROIs) in a furnace utilizing a plurality of thermal imaging cameras;
measuring a surface temperature of the furnace using a radiance measurement obtained from an ROI selected from the plurality of ROIs, including:
determining an effective background radiance affecting the selected ROI utilizing radiance measurements obtained from ROIs different from the selected ROI;
obtaining a compensated radiance by removing the effective background radiance from the radiance measurement obtained from the selected ROI;
converting the compensated radiance to the measured surface temperature of the furnace, wherein the radiance measurement obtained from the selected ROI is obtained from a plurality of pixels in the ROI, averaged over at least one selected from the group consisting of space and time; and
making local adjustments to a fuel flow to burners to control the surface temperatures of the furnace.

11. The method of claim 10 , wherein the effective background radiance affecting the selected ROI is calculated from a geometric view factor-based weighted average of radiance measurements of the surfaces within a hemisphere in front of the selected ROI.

12. The method of claim 10 , wherein the radiance measurements are concurrently obtained; and wherein the surface temperature is measured in real time.

13. The method of claim 10 , wherein the furnace is a steam reformer furnace and each of the plurality of ROIs is a surface region on one selected from a group consisting of at least a reformer tube, a wall, a floor, a ceiling and a flame front.

14. The method of claim 13 , wherein the local adjustments to the fuel flow to the burners are performed to ensure that all reformer tubes operate below a maximum allowable reformer tube wall temperature.

15. The method of claim 14 , wherein the local adjustments to the fuel flow to the burners are performed to mitigate hotspots on the reformer tubes.

16. The method of claim 14 , wherein the local adjustments to the fuel flow to the burners is performed to minimize variation in reformer tube wall temperatures.

17. The method of claim 14 , wherein the local adjustments to the fuel flow to the burners are performed to operate the reformer at a higher reformer temperature without violating the maximum allowable reformer tube wall temperature.

18. A system for measuring furnace temperatures, comprising:
a plurality of thermal imaging cameras and a processing unit configured to obtain radiance measurements from a plurality of regions of interest (ROI) of a furnace using the plurality of thermal imaging cameras, wherein
the thermal imaging cameras are utilized to measure a surface temperature of the furnace using a radiance measurement obtained from an ROI selected from the plurality of ROIs, including:
determining an effective background radiance affecting the selected ROI using a weighted average of radiance measurements obtained from the ROIs that are different from the selected ROI and are within a hemisphere in front of the selected ROI;
the processing unit is employed to obtain a compensated radiance by removing the effective background radiance from the radiance measurement obtained from the selected ROI; and
converting the compensated radiance to the measured surface temperature of the furnace, wherein the radiance measurement obtained from the selected ROI is obtained from a plurality of pixels in the ROI, averaged over at least one selected from the group consisting of space and time.

19. The system of claim 18 , wherein the thermal imaging cameras are automatically retracted upon loss of cooling.

20. The system of claim 18 , wherein the thermal imaging cameras are located outside the furnace to obtain the inside view of the furnace through ports disposed in the furnace walls.

21. The system of claim 18 , wherein the thermal imaging cameras operate at incident radiation wavelength of about 850 nm or about 3.9 μm.

22. The system of claim 18 , wherein a reference body is disposed inside or outside the furnace to calibrate the thermal imaging cameras.

Assignees

• Lumasense Tech Holdings Inc
• Praxair Technology Inc

Inventors

• Dubbs Tim Patrick
• Shaver John Leonard
• Kelley Kreg James
• Raybold Troy M
• Vispute Tushar

Classifications

• G01J5/0044 Primary

  Furnaces, ovens, kilns (G01J5/0007, G01J5/004 take precedence) · CPC title

• G01J5/03

  Arrangements for indicating or recording specially adapted for radiation pyrometers · CPC title

• H04N23/90

  Arrangement of cameras or camera modules, e.g. multiple cameras in TV studios or sports stadiums · CPC title

• G06V10/60

  relating to illumination properties, e.g. using a reflectance or lighting model · CPC title

• H04N23/23

  from thermal infrared radiation · CPC title