真空变压吸附沼气净化过程的仿真研究

摘要

真空变压吸附(VPSA)是一种气体分离技术,该技术运用在沼气净化过程还存在较多的问题,针对该过程吸附塔出口浓度出现的浓度峰问题,运用线性推动力模型(LDF)与Langmuir等温方程对其建立了数学模型,模拟分析了缓冲罐中杂质浓度对吸附步骤出口浓度的影响.结果表明:相同吸附时间下,随着吸附压的降低,二均降结束时会有更多的杂质进入缓冲罐,而缓冲罐中的杂质又会通过一均升步骤进入吸附塔,最终使得吸附步骤出口浓度曲线出现波峰,从而影响了吸附塔出口CH4含量.通过模型的分析,吸附时间随着吸附压不断降低而缩短,可以有效控制杂质进入缓冲罐,从而使吸附塔出口CH4含量提高.%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.