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Show nozzle. The combined kiln and afterburner thermal rating is 125 million BTUlHr and total waste feed to the kiln and afterburner may be up to 29,000 Ibslhr. Burner Description Since a rotary kiln is designed to have a substantial portion of the feed material devolatizing and burning on the wall anyway, the fuel-air ratio and combustion performance of the liquid burners are not considered critical for overall system performance. A simple, rugged burner design that has proved reliable for operation with highly variable liquid wastes was selected. The liquid burners are a multi-fuel design equipped with propane pilot, fuel oil gun for heatup to operating temperature, and a waste liquid gun. There are no swirl chambers, staged air or other special features. Low-NOx burners were considered during design but were not selected. Other Incineration Process Equipment Combustion air enters from the primary air dampers on the liquid burners, secondary air enters through the feed chute damper. Additional air enters around the' seals at both ends of the kiln. The afterburner has no air-tight casing so additional air leaks in through the refractory structure. Oxygen is measured and controlled at the afterburner exit. The plant has a digital process control system with excellent data archiving capability. The stack monitoring includes a continuous NOx monitor so it was possible to examine the effect of operating conditions on NOx emissions in an industrial setting. Permit Limits The plant has three main permits affecting the combustion process, each based on different regulations. An EPA issued permit regulates burning of PCB materials, a Utah Department of Solid and Hazardous Waste permit regulates sampling, storage, processing and burning of other chemical wastes, and a Utah Air Quality permit regulates the combustion, gas cleaning and air emissions. The facility has permit limits on many feed composition and process variables including combustion exit temperature, exit oxygen, total heat release, total weight of waste fed through each port, and hourly total weights for specific elements (see Figure 2). NOx Emissions Based on a scale up from the trial bum results at the Aptus Coffeyville, Kansas plant, the NOx emission limit was set at 22 lbs per hour. This is approximately 114 ppm NOx, or on a heat release basis this is 0.18 lbslmillion BTU (77 nglJ). This is low compared to other applications. For example, it is less |