H_2O和CO_2对焦炭溶损反应动力学的研究

Study on Solution Loss Reaction Kinetics of Coke with H_2O and CO_2

采用自制高温气固相反应连续测定装置,研究了900～1100℃下,CO2,H2O及其混合气体与焦炭的溶损反应.结果表明,焦炭与H2O反应的溶损率远高于其与CO2反应后的溶损率,前者是后者的2～5倍.相比与CO2的反应,焦炭与H2O的反应在颗粒外围更为剧烈,且不易在中心部位生成大的串孔及裂纹.900℃时,与CO2、H2O反应开始的焦炭的主要气化方式分别为微孔生成、小孔扩张;1100℃时,分别为小孔扩张、微孔生成.随着混合气体中H2O含量的增加,焦炭的溶损率不断增加.当[H2O]/[CO2]=5/5和7/3时,焦炭与混合气体的共气化过程中均产生了明显的交互作用.用缩核反应模型描述了焦炭与H2O和CO2气化反应的结果,得反应活化能分别为154.47和214.77kJ/mol.

The effects of CO2, H20 and their mixture on coke degradation were studied from 900℃ to 1100℃ by self-command continuous measurement device for high temperature gas-solid reaction. The results show that the solution loss rate of coke reacting with H2O is 2-5 times of that of the coke with CO2. Compared with the coke reacting with CO2, the chemical reaction of coke with H2O is much more intense in the periphery of coke, and it is not easy to generate big holes and cracks in its center part. The main gasification ways of coke beginning to react with CO2 and H2O are micro-hole formation and pore expansion respectively when the temperature is 900 ℃; that of coke beginning to react with CO2 and H2O are pore expansion and micro-hole formation respectively when the temperature is 1100℃. The solution loss rate of coke increases with increasing of H2O in gaseous mixture. The synergistic effect of coke and H20-CO2 gaseous mixture is apparent when the ratio of H2O to CO2 in the mixture is 5/5 or 7/3 during the gasification process. The shrinking core model was used to describe the gasification results of coke reacting with H2O and CO2. Their activation energy is 154.47 and 214.77 k J/tool respectively.