Experimental And Simulative Studies Of Toluene Removal Technology Using Paraffin Oil

In recent years,the environment problem has become increasingly serious due to the continuous development of industry and the growing scope of human activities.Volatile organic compounds(VOCs),which are harmful to human health and living conditions,are classified as air pollutants.In this paper,toluene,one of typical VOCs,was selected the research material.Firstly,the experimental study on the absorption and desorption process of toluene by paraffin oil was carried out.Then,we adopted Aspen Plus to verify models of absorption and desorption processes based on experimental data,and optimize operational parameters.Finally,a model including absorption-desorption process in the coating and dip dyeing industry was established.The result is as follows:1.Experimental studies on the removal of toluene by paraffin oil were carried out in packed bed and rotating packed bed(RPB),respectively.The results show that the removal efficiency of toluene in packed bed is better than that in RPB,but RPB obtained a far higher value of KGa under the optimal conditions.2.Results of desorption experiment indicate that the toluene desorption efficiency increased with the increasing of temperature(50～90 ℃),gas flow rate(100～300 L· h-1’1)and rotational speed(600-1400 rpm),while decreased with the increasing liquid flow rate(7.2～16.8 L·h-1).Overall liquid volumetric mass transfer coefficient KLa increased with the increasing of temperature and rotational speed,and firstly increased and kept steady at a certain level of gas flow rate,while liquid flow rate had no effect on KLa.3.A desorption model of RPB was set up by Aspen Plus based on the balance of cross section area and volume.The results show that the simulated values agreed well with experimental data with a deviation within±20%.4.Simulated results indicate that the optimal conditions for absorption process were:temperature of 30℃,pressure of 1.8 atm,and gas-liquid ratio of 20:1,and the absorption efficiency was above 99%,the optimal conditions for desorption process:temperature of 140℃,pressure of 1 kPa,and gas-liquid ratio of 5:1,and the desorption efficiency could reach 90%.The concentration of toluene in the exhaust of complete flow scheme was 7.38 ppm,which was inferior to the emission control standard.