| OCR Text |
Show 2.1 .24 and an infinite cylinder. Fig.12. Calculated temperatures inside a plate and a cylinder 873 TEMPERATURES INSIDE A PLATE u=0.20, y0-i)39 KG/M) R-3.33 MM TEMPERATURES INSIDE A CYLINDER 873 i (K) 673 173 J 273 u=0.70, ?0=384 KG/M3, R=6,86 MM x=l 300 TIME (SECONDS) =873 K T"=793 K 600 Fig.13. The effect of particle size on the transient mass. MASS/INITIAL MASS 0.5" 0 4 0 250 TIME (SECONDS) Fig.14. The transient release of steam and volatiles, when u=0.20,calculated. 0.005 u=0.20 PLATE, R=3.3 MM MASS FLOW RATE drying 150 time T , , TIME (SECONDS) • 1 MASS INITIAL MASS - 0.5 - I - 0 300 The two temperature plateaus in the center that was observed in measurements /1/, one at the vaporization temperature and the other at the pyrolysis temperature, and the rapid increase in the temperature after the plateaus, can clearly be seen in the calculated results in Fig.12. In Fig.13. the effect of the particle size on the transient mass can be seen. The drying and the pyrolysis occur partly in overlapping time periods (Fig.14). When the moisture content is high, the drying and the devolatilization become more successive due to the cooling effect of the steam flow, and when the moisture content is low, the processes become more simultaneous. For cylinders and spheres, compared with plates, the processes are more overlapping. |
