Vacuum pressure swing adsorption(VPSA) is a technology for gas separation.There are some problems when it is applied to the process of biogas purification
among which is the concentration peak at the outlet of the column.To solve this problem
we use the linear driving force(LDF) model and Langmuir isothermal equilibrium to build a model and analyze the effect of CO2 concentration in buffer tank on the purity of outlet of adsorption step.The results indicate that CO2 enters the buffer tank in the second pressure equalization-depressurization and then the column in the first pressure equalization-pressurization
finally the concentration peak appears at the outlet of the column
and affects the CH4 concentration.The simulation shows that in order to control the CO2 concentration in buffer tank and improve the purity of the product
the adsorption time should be shorten as the adsorption pressure decreases.