THE CRACKING AMMONIA REDUCTION KINETICS OF DENITRATED URANIUM TRIOXIDE
KANG SHIFANG XIE ZHENFENG GE QINGREN (Chemical Engineering Department, Tianjin University)
The cracking ammonia reduction kinetics of UO_3 denitrated in fluidized bed has been studied with thermograyimetric method. The results show that the reduction kinetics of UO_3 obeys Spencer-Toply equation within 0—95% conversion in range of 550-660℃ which coincides with chemical reaction controlled unreacted-core model. The apparent activation energy of reduction reaction is found to be 133.8 kJ/mol. There is comparison between effects of cracking ammonia and mixture of hydrogen and nitrogen (3H_2+N_2) on reduction rate of UO_3. The effects of partial pressure of hydrogen and water vapour on reduction rate are examined. The hydrogen partial pressure exponent is found to be 0. 57. The water vapour restricts obviously reduction rate of UO_3.