活性炭变温脱附高浓度VOCs的工艺参数优化与评价

Optimization and evaluation of process parameters of thermal desorption ofhigh concentration VOCs using activated carbon at variable temperature

以甲苯为VOCs类代表性的目标污染物,通过搭建实验装置模拟活性炭吸附脱附处理VOCs工艺,并在不同工艺条件下(脱附温度、表观风速、高径比),选取常见评价因子(甲苯脱附率、甲苯浓缩比、脱附能耗比)以探讨不同脱附工况下气体对各床层的脱附情况进行研究。结果表明,甲苯脱附率随脱附温度和表观风速的增加而增加。甲苯浓缩比随脱附温度和高径比的增加,随表观风速的减小而增加,即表观风速是浓缩比的主要控制因素。在中温范围内,低风速、高径比的甲苯浓缩比小于高风速、高径比。在高温范围内,低风速、高径比的甲苯浓缩比仅在峰值段大于高风速、高径比。脱附温度越高,表观风速越小,高径比越大,相同脱附率下的甲苯浓缩比越大。脱附能耗比随脱附温度和表观风速的减小,高径比的增加而降低,即表观风速是能耗比的主要控制因素。高温低风速时的能耗比比中温高风速时的能耗比低。当脱附温度80℃、表观风速0.3 m·s^(-1)时,脱附能耗比最低为1.1706 kJ·g^(-1)。本研究可为变温脱附工程化应用的低碳化工艺优化提供参考。

An experiment device was built to simulate the adsorption and desorption process of activated carbon to treat VOCs,by taking toluence as the reprentative target pollutant of VOCs.Common evaluation factors(toluene desorption rate,toluene concentration ratio,desorption energy consumption ratio)in the process were selected to study the gas desorption of each bed under different desorption conditions(desorption temperature,cross-section wind speed,height to diameter ratio).The results showed that the toluene desorption rate increased with the increase of desorption temperature and cross-section wind speed.The concentration ratio of toluene increased with the increase of desorption temperature and height to diameter ratio,and the decrease of cross-section wind speed,which was the main control factor of concentration ratio.In the range of middle temperature,the concentration ratio of toluene at low wind speed and height diameter ratio was smaller than that at high wind speed and height-diameter ratio.In the range of high temperature,the concentration ratio of toluene at low wind speed and high diameter ratio was higher than that at high wind speed and heightdiameter ratio only at the peak stage.At the same desorption rate,greater toluene concentration ratio would be achieved under higher desorption temperature,lower cross-section wind speed,and higher height-diameter ratio.The desorption energy consumption ratio decreased with the decrease of desorption temperature and crosssection wind speed,and the increase of height-diameter ratio.The cross-section wind speed was the main control factor of energy consumption ratio.The desorption energy consumption ratio at high temperature and low wind speed was lower than that at medium temperature and high wind speed.When the desorption temperature was 80℃and the apparent wind speed was 0.3 m·s^(-1),the lowest desorption energy consumption ratio was 1.1706 kJ·g^(-1).This study can provide reference for low-carbon improvement in the engineering application of variable temperature desorption.