Research Article
Influence of Sorbent Characteristics on Fouling and Deposition in Circulating Fluid Bed Boilers Firing High Sulfur Indian Lignite
Table 1
Proximate, ultimate, chemical composition of ash, ash fusion temperatures, and ash deposition indices of high sulfur lignite.
| Sample ID | Sample 1 Lignite Giral | Sample 2 Lignite Giral | Sample 3 Lignite Giral | Sample 4 Lignite Giral | Sample 5 Lignite Giral | Sample 6 Standpipe blockage Giral |
| Proximate analysis (wt % on air dried basis) | Moisture | 11.8 | 10.0 | 29.6 | 29.1 | 15.0 | 9.6 | Volatile matter | 37.5 | 29.5 | 27.8 | 28.4 | 33.7 | 37.8 | Ash | 18.6 | 34.5 | 15.6 | 13.9 | 18.7 | 26.8 | Fixed carbon | 32.1 | 26.0 | 27.0 | 28.6 | 32.6 | 25.8 | Gross calorific value Cal/g | 4865 | 3445 | 3645 | 4059 | 4720 | 4030 |
| Ultimate (wt % on air dried basis) | Carbon | 51.6 | 38.5 | 35.3 | 39.5 | 49.1 | 41.0 | Hydrogen | 3.8 | 2.5 | 2.6 | 2.6 | 3.3 | 4.0 | Nitrogen | 0.6 | 0.6 | 0.9 | 0.8 | 0.7 | 0.6 | Sulfur | 6.94 | 5.5 | 4.1 | 4.7 | 6.70 | 4.0 |
| Chemical composition of ash (wt %) | SiO2 | 25.9 | 39.2 | 41.0 | 36.2 | 25.1 | 34.1 | Al2O3 | 12.6 | 27.5 | 22.0 | 17.7 | 14.2 | 14.8 | Fe2O3 | 28.8 | 16.5 | 21.4 | 25.7 | 26.4 | 11.9 | TiO2 | 1.3 | 2.1 | 2.3 | 2.4 | 1.5 | 1.6 | CaO | 8.3 | 4.2 | 3.7 | 5.1 | 6.6 | 3.3 | MgO | 3.3 | 2.1 | 2.2 | 2.2 | 3.1 | 1.3 | Na2O | 7.2 | 1.4 | 1.7 | 2.8 | 8.3 | 4.1 | K2O | 0.3 | 0.6 | 0.4 | 0.4 | 0.3 | 0.2 | SO3 | 11.0 | 6.2 | 5.7 | 7.2 | 13.7 | 28.7 |
| Ash fusion temperatures °C (oxidizing atmosphere) | Temperatures | 1 | 2 | 3 | 4 | 5 | 6 | Deformation T1 | >1152 | 1267 | 1275 | 1311 | >1152 | 1244 | Softening T2 | >1214 | 1290 | 1300 | 1321 | >1214 | 1260 | Hemisphere T3 | >1230 | 1307 | 1333 | 1364 | >1230 | >1300 | Fusion T4 | >1250 | 1377 | 1360 | 1385 | >1250 | >1300 |
| Ash deposition indices | Si ratio | 39.06 | 63.22 | 60.02 | 52.31 | 41.01 | 67.4 | Base/acid | 1.20 | 0.36 | 0.45 | 0.64 | 1.78 | 0.41 | Iron index | 34.56 | 5.93 | 9.63 | 16.45 | 47.0 | 4.9 | Fe/Ca | 3.47 | 3.93 | 5.78 | 5.04 | 4.0 | 3.6 | Fe + Ca | 37.1 | 20.7 | 25.1 | 30.8 | 33.0 | 15.2 |
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