# US 11,079,283 B2 · Temperature measurement system for furnaces > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,079,283 B2 - Document ID: US11079283B2 - Status: Granted - Kind: B2 - Application number: 16/364,559 - Filed: 2019-03-26 - Published: 2019-07-18 - Granted: 2021-08-03 - Earliest claimed: 2016-04-01 - Assignees: Praxair Technology, Inc. - Applicants: LumaSense Technologies Holdings, Inc.; Praxair Technology, Inc. - Inventors: Tim Patrick Dubbs; John Leonard Shaver; Kreg James Kelley; Troy M Raybold; Tushar Vispute - Web page: https://patentgrep.com/patent/US11079283B2 ## CPC - G01J 5/0044: {Furnaces, ovens, kilns (G01J5/0007, G01J5/004 take precedence)} - G01J 5/03: Arrangements for indicating or recording specially adapted for radiation pyrometers - G01J 5/07: Arrangements for adjusting the solid angle of collected radiation, e.g. adjusting or orienting field of view, tracking position or encoding angular position (optical collimating elements G01J5/0806) - G06V 10/235: {based on user input or interaction} - G06V 10/60: relating to illumination properties, e.g. using a reflectance or lighting model - H04N 23/23: from thermal infrared radiation - H04N 23/90: Arrangement of cameras or camera modules, e.g. multiple cameras in TV studios or sports stadiums - G01J 5/80: Calibration (using comparison with reference sources G01J5/52) - G01J 5/802: {by correcting for emissivity} - G01J 5/804: {using atmospheric correction} - G01J 2005/0077: {Imaging} - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) - G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## 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. ## Claims ### Claim 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. ### Claim 2 (depends on 1) 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. ### Claim 3 (depends on 1) The method of claim 1, wherein the radiance measurements are concurrently obtained; and wherein the surface temperature is measured in real-time. ### Claim 4 (depends on 1) 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. ### Claim 5 (depends on 1) 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. ### Claim 6 (depends on 1) 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. ### Claim 7 (depends on 1) The method of claim 1, further comprising: correcting the radiance measurement obtained from the selected ROI for an emissivity of the selected ROI. ### Claim 8 (depends on 7) 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. ### Claim 9 (depends on 7) 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. ### Claim 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. ### Claim 11 (depends on 10) 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. ### Claim 12 (depends on 10) The method of claim 10, wherein the radiance measurements are concurrently obtained; and wherein the surface temperature is measured in real time. ### Claim 13 (depends on 10) 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. ### Claim 14 (depends on 13) 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. ### Claim 15 (depends on 14) 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. ### Claim 16 (depends on 14) 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. ### Claim 17 (depends on 14) 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. ### Claim 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. ### Claim 19 (depends on 18) The system of claim 18, wherein the thermal imaging cameras are automatically retracted upon loss of cooling. ### Claim 20 (depends on 18) 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. ### Claim 21 (depends on 18) The system of claim 18, wherein the thermal imaging cameras operate at incident radiation wavelength of about 850 nm or about 3.9 μm. ### Claim 22 (depends on 18) The system of claim 18, wherein a reference body is disposed inside or outside the furnace to calibrate the thermal imaging cameras.