OCR Text |
Show - 16 - Simultaneous me asureme nts of particle t e mpe ratures, sizes and particle masse s along an e ntrained-flow r eactor are required in order to find out the r eal reaction products and the kinetical constants. The effect of kinetics could even be insignificant in some cases. The lower combustion rate and the higher particle temperature compared to the model 3 can be explained so that a part of the char is directly oxidized to CO 2 • This can be seen from Fig. 7a. Another explanation is that some of the CO produced is combusted close to the particle, which consumes oxygen, lowers the combustion rate and increases the particle temperature. aoor---------~r---------~----------~ r"\ Fig. 1 o. The comparison c 1700 of measured and calculated particle temperatures. w ex => I- ~ 1(0) ~ L W I- 1600 w -.J U a~: 1400 cr: CL YOUNG AND HI kSA DIAMETER 0.069 'Vi T G • T w • 1013 K Calculations are based on diffusion co trol 1~ .:~- :-----"''------=0:-':.O : O-:-----------0.. .I.....:12~=-=------.J.O1 6 OXYGEN MOLE FRACTION The calculated particle temperatures are compared to measurements /14/ in Fig. 10. Again, it can be seen that the model 3 gives too low particle temperatures. However, it can give too high combustion rates. This too high combustion rate is avoided in model calculations by using apparent kinetical constants. This procedure is not physically correct, since the use of kinetical constants in the calculations (model 3', Fig. 7a) decreases the particle temperature even lower. |