流化床微波解吸载甲苯活性炭研究

Study on the desorption of fluidized toluene-exhausted activated carbon by microwave irradiation

利用微波作为加热手段,采用椰壳基颗粒活性炭(GAC)为吸附剂,经吸附甲苯达饱和后进行流化床微波解吸实验。结果表明:(1)前4min,轻微流化状态下的甲苯浓度总体小于中等流化状态;4min后,轻微流化状态下的甲苯浓度逐渐大于中等流化状态。轻微流化状态下的甲苯解吸效果不理想,与中等流化状态有很大差距。流化床微波解吸适宜的载气线速为73.4cm/s。(2)在整个流化床微波解吸过程中,300℃下的甲苯浓度总体均高于200℃。300℃下的甲苯解吸量在很短的时间内迅速上升,7min后解吸率就达到了90%,20min就超过了95%;但200℃下,无论是甲苯解吸量曲线的上升速率、达到稳定所需的时间还是解吸量最大值,都小于300℃,40min后解吸率也仅达到75%左右。流化床微波解吸适宜的温度为300℃。(3)流化床微波解吸载甲苯活性炭具有解吸迅速、解吸率高的特点。同时,微波对物质加热的非接触性、流化床微波解吸中活性炭颗粒的流动性以及较高的传质速率是保证流化床解吸高效性的关键因素。

Desorption of toluene-exhausted granular activated carbon（GAC） by microwave irradiation was conducted at fluidized state.Results showed that in the first 4 min,the concentration of toluene at slightly fluidized state was lower than that at medium fluidized state.After 4 min,the concentration of toluene at slightly fluidized state was higher than that at medium fluidized state.Toluene desorption at slightly fluidized state was much worse than that at medium fluidized state.The optimum load gas velocity was 73.4 cm/s.Better toluene desorption performance was found when desorption temperature was 300 ℃,gave the load gas velocity of 73.4 cm/s and desorption temperature of 300 ℃,the desorption rate of GAC was 90% after 7 minutes,and the desorption rate reached higher than 95% after 20 minutes.The toluene desorption rate,the stabilized time and the maximum desorption amount obtained at 200 ℃ all lower than that at 300 ℃.The desorption rate was only about 75% after 40 min of microwave irradiation.So,the optimum desorption temperature was 300 ℃.Desorption of toluene-exhausted GAC by microwave irradiation had the characteristics of quick desorption rate and high treatment efficiency,the main reasons were non-contact heating type of microwave irradiation,high mass transfer rate and fluidity of GAC.