OCR Text |
Show entrained the air in through the top of the test rig. The enclosure was selected to curtail crossflow effects which normally occur in an ambient environment, and to a greater extent, in a tunnel kiln. The final series of experiments compared flame length between round and slotted burners. The results measured for burner families A and B showed visible flame length deceased 10 to 3 0 % with the slotted burner. Field Results Brick plants were selected initially for field slotted burners. Temperature uniformity was improved by increasing the mixing and movement of the furnace gases. Quality records were also encouraging in that the manufacturer noted a reduction in scrap from 3.2% to 2.5%. This reduction was immediately noted after the retrofit, and the manufacturer reports similar improvements when firing a variety of brick product. The brick manufacturer has increased the throughput of the slotted burners to further drive production; this has been done without detriment to the product quality. Previous to 2000 2000 r 500 k 1500 1000 500 Preheat Zone (Retrofit Test) 16 High Velocity Burners With Slotted Discharge Nozzles Travel Distance Through Kiln Travel Distance Through Kiln Figure 9 Baseline Tunnel Kiln Results Figure 10 Retrofit Tunnel Kiln Results testing of slotted nozzles. In all cases, a retrofit of the tile only was made to the existing burner hardware. Figures 9 and 10 depict six measured temperatures throughout the brick stacking for the baseline and retrofit cases, respectively. The location of the data shown is relative to the preheat zone where the 16 high velocity burners were retrofitted. The measurements were made using an electronic data recording device that travels with the product as it moves through the tunnel kiln. The results show a reduction in the temperature variance when using the the slotted burner retrofit, the manufacturer was hesitant to increase the throughput of the existing round high velocity burners for concerns of overheating the deck of the kiln car (top-fired burner arrangement). This prevented the manufacturer from increasing burner throughput. The manufacturer is now considering removal of recirculating fans, located in lower temperature regions of the preheat zone (typically not fired), and replacing them with additional slotted high velocity burners. |