Diagnostic Field Measurements in High Temperature Industrial Scale Process Equipment

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schedule furnace maintenance. As shown in Fig. 2, a typical wall thermal image was acquired while focusing camera through the furnace tubes onto a portion of the furnace wall. Since the tubes are cooler than the wall, they appear black in Fig. 2. Wall surface temperatures are not uniform from port to port. The temperature variation may be caused by a combination of burner position and physical structure of the refractory. Shown in the Fig. 3 is a typical tube thermal image. Since the wall is hotter than the tubes, the wall appears as rectangular regions of white and red in Fig. 3 while the tubes appear as colors ranging from black to red. The uneven temperature distribution on the tube surface can be easily observed from this false-color images. Care in interpreting these thermal images is required because the distance from the top/bottom (right/left) of the wall (tube) to the camera is significantly greater than the distance from the center of the wall (tube) to the camera; consequently the camera calibration that is valid for the center of the image is not appropriate for the edges of die images. Even with this caveat, it is seen that there is significant variation (hot spots) of the wall (tube) temperature within the furnace. Figure 2. False-color diermal image of furnace wall viewed through tubes. The temperature key is to the right of the image. The tubes appear as rectangular black regions because diey are cooler than the wall. Using our innovative image acquisition/analysis software system, a region of interest (ROI) was selected and temperature values and distributions were quickly displayed on the computer screen. Table 1 presents average temperatures for selected R O I from the center regions of images collected from a selected port at each furnace level. Table 1. Typical target surface temperatures (in °C) for selected areas. Levels 1st floor 2nd floor 3rd floor Wall 1132.9+9.3 1143.6±9.2 1148.2±12.2 Outlet Tube 965.7±4.2 982.2±3.3 1030.7±3.7 Inlet Tube A 947.8±5.0 979.6±3.4 956.6±6.0 Inlet Tube B 953.5±4.7 937.1+5.5 979.4±4.9 •5-