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Show COMBUSTION MEASUREMENTS IN AN INDUSTRIAL GAS FIRED ALUMINUM RECYCLING FURNACE 4 Water Jacket 0 0.875 in (22.2 m m ) Suction Tube ^ 0 0.375 in (9.5 mm) to condenser coils and suction pump Water \ \ W f e r Outlet lnlet Figure 3. Schematic drawing of gas sampling probe. two condenser coils eliminated the water from the gases prior to species concentration measurement by the gas analyzers. The sampled gases were analyzed in real-time with four on-line gas analyzers, yielding measurements in either volume percent (vol%) or parts per million on a dry basis (ppmvd): a Nova 301-BD infrared analyzer for C 0 2 , two Land Combustion 6500 electrochemical analyzers for 02, N O , and low (< 2000 ppmvd) and high (> 2000 ppmvd) CO, and a North American Enviromate electrochemical analyzer for duplicate 02, N O , and low C O measurements. C O concentrations were limited to 40,000 ppmvd, N O concentrations to 4000 ppmvd, and C 0 2 measurements to 30 vol%. The accuracy reported for the C 0 2 measurement is ±0.3%. The manufacturer-specified accuracy for both electrochemical analyzers was ±0.05% for 02, and ± 4 % and ±100 ppmvd for C O measurements greater than and less than 2000 ppmvd, respectively. All analyzer units were carefully calibrated before and after each test using research-grade calibration gas standards for 02, C 0 2 , C O , and N O . The gas calibration standards were designed to provide instrument calibration over the range of values anticipated. Calibration gas concentrations were: o2 CO: C02: NO: 21 vol% (atmospheric) 900 ppmvd and 25,000 ppmvd (2.5 vol%) 10.0 vol% 900 ppmvd and 1800 ppmvd Research grade pure nitrogen was also used to test for leakage in the gas sampling train. Very good agreement was observed throughout the tests in the duplicate measurements for the different electrochemical analyzers. Response time for species measurements was estimated for the sample train used in the tests to be approximately 2 min for the C 0 2 measurements, and 1 min for all other gas species. Higher levels of gas species concentrations than anticipated were encountered in the combustion space. Preliminary concentration measurements revealed that, in several locations in the furnace, the concentrations exceeded the measurement limits of the analyzers. Therefore, a dilution system was used to make measurements in these locations possible. Research grade pure nitrogen was mixed with the sampled combustion gases in known proportions prior to on-line gas concentration analysis. The measured results were then scaled by the appropriate scaling factor using the known combustion gas and dilution nitrogen flow rates. |