Process analysis of temperature swing adsorption and temperature vacuum swing adsorption in VOCs recovery from activated carbon

[Display omitted] •The adsorption process of TSA and TVSA for VOCs in waste gas was studied, and the parameters of process purification and recovery of VOCs were discussed.•The dynamic adsorption experiment was completed,The adsorption isotherm of benzene on activated carbon was determined.•A mathematical model was established to simulate the process of TSA and TVSA.•The initial range of the optimal hot-cold purge ratio is determined.•The influence of vacuum step on adsorption and desorption step is discussed. In order to better guide the design of industrial process for purification and recovery of VOCs, temperature swing adsorption (TSA) and temperature vacuum swing adsorption (TVSA) process for VOCs purification and recovery were studied systematically with activated carbon adsorbent. The adsorption and desorption behaviors of benzene on activated carbon in above two processes were investigated systematically. Effects of operating parameters on process performances were further analyzed, including as regeneration temperature, purging feed ratio and hot–cold purging ratio. The results showed that the increase of hot–cold purging ratio (HP/CP) could obtain the same regeneration effect as the increase of desorption temperature. Increasing the feed purge ratio without increasing the hot–cold purging ratio is not conducive to bed regeneration, because a large number of cold purge gases cannot utilize the residual heat of temperature wave, thus reducing the desorption effect of the cooling step on the bed. In addition, the vacuum step can enhance the regeneration ability of hot nitrogen to the bed at the same regeneration temperature, making the bed regeneration of TVSA process more thorough. Temperature in the middle and lower part of the bed in TVSA process was higher and the regeneration was more thorough. In conclusion, TVSA has more obvious advantages than TSA in terms of energy consumption, hot or cold purge volume and bed regeneration.