Combustion Characteristics of Occidental Coal-Water Mixtures

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55,000 Btu/ft -hr which is representative of the heat release rate in an oil-fired utility boiler. Furnace heat release rates that more closely simulate the combustion environment of pulverized coal-fired boilers can be achieved by reducing the boiler firing rate. Two burners were used in the program. The coal burner was a scaled down version of a utility boiler burner. The CWM burner was a composite design which simulates many industrial type burners using a combination gas and oil burner. Each burner has variable-vane-angle air registers to impart swirl to the combustion air flow. An internally mixed air atomizer was used with the CWM's. This atomizer incorporated a tungsten carbide insert within the discharge orifice to minimize erosion. The atomizer was developed by KVB during a previous coal-oil mixture test program, and is proprietary to ORC. For some of the tests, the CWM burner also utilized a water cooled atomizer assembly to maintain the CWM's at temperatures under 120°F. The burner placement relative to the boiler during the firing of pulverized coal and CWM is shown in Figure 2. The burner arrangement shown for the parent coal tests was initially used with the CWM's; however, poor flame stability and turndown was experienced. To provide a hotter flame stabilizing zone, a refractory section was added in the initial section of the boiler furnace as shown in Figure 2b. This CWM burner configuration resulted in good flame stability over a turndown range of 3:1 with NO emissions equal to or less than the parent coal. The CWM fuel handling system is shown in Figure 3. All air and gas flows into the combustion facility were measured by calibrated rotameters or venturi flow meters. The CWM flow rate was measured by a micromotion mass flowmeter. Temperature measurements were made using chrome1-alumel thermocouples. The measurements of primary interest were the gaseous and particulate emissions leaving the boiler from which combustion efficiency, gaseous emis­sions and ash characteristics were determined. The gaseous emissions were 11 KVB72-P327 D194