气体变压吸附非等温非绝热非平衡模型计算

Numerical simulation of fixed-bed adsorption by non-isothermal non-adiabatic and non-equilibrium model

分析了固定床吸附过程中流动、传热和传质过程,将多孔介质内传输模型应用于吸附过程研究,建立了大含量强吸附的非等温非绝热非平衡模型,传质过程采用线性驱动力模型.应用有限体积差分法对方程进行离散,使用SIMPLE法进行压力-速度修正,使用迭代法进行方程求解.采用此新模型计算了定壁温条件下圆筒形沸石13X吸附床对质量浓度为0.176 kg/m3的二氧化碳/氮气双组分气体的吸附过程,并对结果进行了分析.模型可以合理地计算吸附传质与传热之间的耦合关系,结果符合前人的实验结果.计算结果表明:吸附过程中温度变化非常显著对吸附量的增大和处理周期的缩短都是不利的,对吸附过程温度的变化进行抑制是提高吸附分离效果的有效途径.

The characteristics of flow,heat and mass transfer of fixed-bed adsorption have been analyzed.A two dimensional thermal non-equilibrium,non-adiabatic and mass non-equilibrium mathematical model has been developed to simulate the coupled heat and mass transfer in a porous media undergoing a strong adsorption by applying the transmission model in porous media.Moreover the mass transfer is described by linear drive force model.The numerical solution of the equations is obtained by using the finite volume method,the SIMPLE algorithm for the pressure-velocity coupling and an iterative method have been used to solve the discrete equations.The adsorption process of 0.176 kg/m^3 carbon dioxide and nitrogen binary mix gas on zeolite 13X has been calculated,and result has been analyzed.The new model can describe the coupling between the heat and mass transfer and the results consistent with that by the former.The calculated results showed that the rise of temperature has bad effect on the performance of adsorption,and reducing the span of temperature is an effective measure to improve the adsorption productivity and purity of the product.