OCR Text |
Show suction pyrometer, ignitors and flame detector access ports. Continuous measurements of NO, CO, CO2, O2 and UHC were taken with the following instrumentation: NO/NOx TECO Model 10 (chemiluminescence) O2 Teledyne 326A (microfuel cell) CO2/CO Anarad AR600R (nondispersive infrared) CO Anarad AR500R (nondispersive infrared) UHC Beckman Model 400 (flame ionization) In addition to the continuous measurements, wet chemistry impingers and specific ion electrodes were used to measure -CN and NH3 for selected conditions. Solid samples were collected and proximate and ultimate analyses were obtained for selected conditions. Temperatures were measured by bare thermocouples, which were corrected, through comparison with suction pyrometer measurements at selected conditions. Nominal running conditions were 16.1 kW (55,000 Btu/hr), 120 percent theoretical air at the exit, ambient temperature combustion air and 70 percent through 200 mesh Utah coal. The coal analysis is given in table 1. RESULTS To date, N0X reductions of over 70 percent from baseline have been found on Utah coal in the fuel-staging combustor. The impact of stoichiometry, residence time and fuel fraction on N0X reduction is discussed in the following paragraphs. Stage Stoichiometry Second-stage stoichiometry was found to be an important parameter in fuel staging. During the tests, stoichiometry was varied by fixing the fuel flow to each stage and varying the air flow to obtain a range of first- and second-stage stoichiometries. The final stage 8-9 |