OCR Text |
Show sensitive to the specific gas to be analyzed. Nitrogen oxide (NO) was measured on-line with a Thermo Electron Model 10 AR chemi-1uminescent analyzer. The accuracy of these methods of analysis, which ranged from 5- 8 percent, has also been described previously (4). Quench Water Ion selective electrodes were used to analyze the probe quench water for dissolved HCN, MH3 and H2S. Accuracies (standard deviation) averaged 2.55% for cyanide ion (CN"), 1.81* for sulfide ion (S~) 3.44% for ammonia, each over a wide range of concentration. Sulfite ion was present from S02 dissolution in the quench water. Sulfite ion was oxidized with ri202 to yield sulfate ion. An ion chromatograph was used to measure the levels of sulfate dissolved in the probe quench water. The maximum precision-limits of the ion selective elctrode analysis were determined to be between + 2 and 5% for all species measured. The precision-limits of ion chromatographic analysis were determined to be between + 2 to 4 percent for samples which had 5 mg/A of sulfate. When samples contained less than 5 kg/A of sulfate, the error increased to + 10 percent. Accuracies of this procedure are reported in detail by Highsmith (12). Solids. An ultimate analysis of the raw coal and char samples to determine carbon, hydrogen, nitrogen, and ash was done on a Perkin Elmer Model 240 elemental analyzer. The solid sulfur was measured with a LECO Corp. sulfur analyzer. Oxygen was determined by difference. The precision-limits associated with ultimate analysis varied considerably. Ash was measured consistently low with precision-limits of approximately ± 15 percent (13). The carbon and hydrogen varied between ± 5 ana 10 percent. Nitrogen precision-limits were between + 10 and 15 percent. Sulfur analysis of standard coal and char samples yielded precision-limits between + 4 and 6 percent. Since oxygen was determined by the difference between the ultimate and sulfur analysis results, the precision of oxygen measurement varied considerably and was between + 10 and 15 percent. The procedures and accuracies haye been previously reported in detail (4,12,13). 6-7 |