高传热和传质性能复合吸附剂的研发

为解决吸附剂强化传热和强化传质之间的矛盾, 以氯化钙和木屑为原料, 采用炭化活化造孔的方法强化传质, 通过加入膨胀石墨强化传热, 考察了炭化活化温度和膨胀石墨加入比例对复合吸附剂性能的影响. 宏观的吸氨性能测试以及微观的参数表征表明炭化活化法制备的吸附剂孔隙发达, 氯化钙含量高而且分布均匀, 强化了吸附氨气过程中的传质速率; 炭化活化温度对样品的氯化钙含量和结晶度, 吸附量以及吸附速率都有重要的影响. 膨胀石墨的加入强化了吸附剂的传热, 提高了吸附速率. 实验结果表明, 500℃温度下制备的吸附剂, 在膨胀石墨含量为30%时, 其在0.5 h内的吸附速率较快, 在吸附时间分别为10, 20和30 min时, 其吸附量达到0.37, 0.47和0.53 g/g, 而且解决了氯化钙吸氨过程中的膨胀结块问题.

Preparation of composite adsorbent with high performance of heat and mass transfer

To solve the contradiction between enhanced mass transfer and enhanced heat transfer, fir sawdust and CaCl₂ are selected as raw materials and the mass transfer is enhanced by carbonizing and activating the sawdust and heat transfer is enhanced by adding expanded graphite into the adsorbent. The effect of the preparation temperature and the expanded graphite content on the adsorption performance is investigated. The results show that the new adsorbent exhibits a high mass transfer performance due to high porosity, uniform distribution and high content of CaCl₂. The carbonization and activation temperature have an important effect on the content and crystallinity of CaCl₂, adsorption amount and adsorption rate. The addition of expanded graphite into the adsorbent can enhance the heat tranfer and fasten the adsorption rate. The experimental results indicate that the adsorbent prepared at 500℃ and with the expanded graphite content of 30% has the best performance, which adsorbs ammonia as high as 0.37, 0.47 and 0.53 g/g at the adsorption time of 10, 20 and 30 min, respectively.