分子筛变压吸附产氧装置数学模型

A mathematical model of pressure swing adsorption bed of air separation unit

目的 建立分子筛变压吸附产氧装置的数学模型 ,研究影响吸附特性的因素对产氧浓度的影响。 方法 主要以理论方法进行研究 ,即针对实际系统做出相应假设 ,用数学模型表达物理模型。该模型未考虑吸附过程的热效应 ,认为吸附过程为等温 ;采用了 L angm uir等温吸附方程模拟分子筛的吸附特性 ;用线性驱动力方程描述传质过程 ;模型的数值求解方法采用有限差分法 ;分析了供气压力、流速和长径比等对产氧浓度的影响。 结果 在一定条件下 ,入口气流速度越小系统产氧浓度越高 ;供气压力越高产氧浓度越高 ;冲洗流量越大系统产氧浓度越高 ,但冲洗流量的增大将使氧回收率减小。 结论 必须同时考虑影响产氧浓度的各因素。机载产氧系统可以在有限的供气压力下满足要求。

Objective To establish a mathematical model of molecular sieve concentrator with pressure swing adsorption, so as to explore the effects of various factors influencing the mole fraction of oxygen. Methods Hypothesis was made based on the actual system, and the physical model was expressed by mathematical model. The thermal effect during adsorption was not taken into consideration. The binary Langmuir equilibrium adsorption equation was adopted to describe the dynamic property between the gas and adsorbent. The linear driving force (LDF) model was applied to describe the mass transfer rate. Numerical solutions were obtained by finite difference method. The effects of parameters, such as the pressure and velocity of inlet gas, cycle time, on the performance of the system were analyzed. Results Under certain circumstance, mole fraction of oxygen increases with the decrease of velocity and the increase of pressure of inlet gas. The increase of the velocity of purge is helpful to mole fraction of oxygen, but can lead to lowering down of O 2 recovery rate. Conclusion All the factors influencing mole fraction of oxygen should be considered simultaneously. Onboard oxygen generating system can satisfy the request of inlet pressure.