Breakthrough Characteristics And Prediction Of Multicomponent VOCs Adsorption On Polymeric Resins Under Ouasi-adiabatic Condition

Gasoline vapor is mainly produced in gasoline production,transportation and use,which are important VOCs sources.The emission of gasoline,which is high concentration of hydrocarbon mixtures,not only waste resources,but also pollute the environment and harm human health.Therefore,it is an urgent task to removal and recovery of gasoline vapor.Adsorption is widely used for gasoline vapor recovery due to the low cost,high efficiency and recyclability.However,many studies mainly focused on single VOC adsorption under constant temperature.In this paper,hypercrosslinked resin NDA-150 and macroporous resin NDA-1800 were selected as adsorbents.The toluene,cyclohexane and n-pentane,which are the representative components of gasoline,were chosen as adsorbates..Breakthrough curves and temperature rise of single,binary or ternary of toluene,cyclohexane,and n-pentane were studied,and compared with activated carbon.Moreover,heat and mass transfer model for the multi-components VOCs adsorption under quasi-adiabatic condition was established to predict the breakthrough curves and temperature rise.The main conclusions are as follows:(1)The adsorption characteristics of single-component toluene,cyclohexane and n-pentane on NDA-150 and NDA-1800 in fixed bed under quasi-adiabatic condition were studied,and compared with those on activated carbon.Also,the mass and heat transfer model was used to predict the breakthrough curves and temperature rise.The results showed that the breakthrough adsorption capacity was positively correlated with the concentration of adsorbate,the breakthrough adsorption capacity(per gram of adsorbents)followed the sequence:GAC>NDA-150>NDA-1800;the maximum temperature rise in fixed bed was positively correlated with the concentration of adsorbate,following the sequence of GAC,NDA-150,and NDA-1800.Compared with GAC,the adsorption capacities of NDA-150 and NDA-1800 were lower,but the maximum temperature rise of NDA-150 and NDA-1800 decreased significantly by 22.2%and 47.7%,respectively.In addition,the average relative deviation of breakthrough times and maximum temperature rises of three VOCs on two adsorbents between the predicted and experimental data were less than 10%and 15.8%,respectively.The sensitivity analysis of parameters showed that the adsorption breakthrough time was positively correlated with wall heat transfer coefficient h0,column height L,and negatively correlated with gas velocity U,ambient temperature To and initial concentration C0.Among these parameters,U,C0 and L had greater influence on the adsorption breakthrough time.The maximum temperature rise was positively correlated with L,C0 and T0,and negatively correlated with U and h0.T0,h0 and C0 had greater influence on the maximum adsorption temperature.(2)The adsorption characteristics of binary and ternary mixtures of toluene,cyclohexane and n-pentane on NDA-150 and NDA-1800 in fixed bed under quasi-adiabatic conditions were studied and compared with activated carbon.Meanwhile,mass and heat transfer models were used to predict the breakthrough curves and temperature rise.The results showed that there existd the competitive adsorption among adsorbates.The adsorption forces of three adsorbated on two adsorbents were in the sequence of toluene,cyclohexane and n-pentane.Compared with GAC,the adsorptive selectivities of the two resins were lower,but the maximum adsorption temperature rises decreased by 31.08%and 56.8%respectively.In addition,the average relative deviation of breakthrough times and the maximum adsorption temperature rises between the predicted and experimental data were 15.9%and 18.96%,12.5%and 8.64%for binary and ternary VOCs,respectively,The sensitivity analysis of parameters showed that the sensitive parameters of binary and ternary VOCs adsorption were the same as that of single VOCs.The adsorption breakthrough time was positively correlated with h0,L,and negatively correlated with U,T0 and C0.Among these parameters,U,C0 and L had greater influence on the adsorption breakthrough time.The maximum adsorption temperature rise was positively correlated with L,C0 and T0,and negatively correlated with U and h0.The T0,h0 and C0 had greater influence on the maximum adsorption temperature rise.