Abstract:

Double reflux pressure swing adsorption is a pressure swing adsorption process in which the feed is carried out in the middle of the adsorption tower, and the top and bottom of the tower are respectively reflowed with light and heavy components, and two high purity and high recovery product gases can be simultaneously produced. In this paper, a LiLSX zeolite synthesized by the laboratory was used as the adsorbent, meanwhile, numerical simulation of a two-bed dual-reflux pressure swing adsorption air separation process was carried out with feed mixture (78%N₂/21%O₂/1%Ar) using the commercial software Aspen Adsorption. The adsorption and desorption pressure are 2 bar and 0.3 bar, the feed flow rate is 0.4 m³/h, the light and the heavy component reflux flow rate are 0.095 L/min and 5.22 L/min. Ultimately, the purity of O₂ and N₂ reach 95.67% and 98.25% in their respective product gas, and the recovery rates are 94.60% and 99.91%, respectively. Besides, effects of operating parameters (the feed position, duration of feed step, light reflux flow rate, heavy product flow rate) on the process performances were investigated, which was more helpful for understanding this process.

Key words: dual-reflux, pressure swing adsorption, air separation, LiLSX zeolite, numerical simulation

摘要：

双回流变压吸附是一种在吸附塔中间位置进料，塔顶和塔底分别采用轻、重组分回流的变压吸附过程，能够同时生产两种高纯度、高回收率的产品气。以实验室自主合成的LiLSX分子筛为吸附剂，利用Aspen Adsorption模拟软件，对进料组成为78%N₂/21%O₂/1%Ar的实际空气进行了两塔双回流变压吸附的模拟研究。模拟结果表明：当原料气为78%N₂/21%O₂/1%Ar，吸附压力为2 bar(1 bar=10⁵ Pa)，解吸压力为0.3 bar，进料量为0.4 m³/h，轻组分回流流量为0.095 L/min，重组分回流流量为5.22 L/min时，能够得到体积分数为95.67%的O₂和体积分数为98.25%的N₂，回收率分别为94.60%和99.91%。并且进一步探究了进料位置、吸附时间、轻组分回流流量、重组分产品气流量等因素对O₂和N₂两种产品气纯度和回收率的影响。

关键词: 双回流, 变压吸附, 空气分离, LiLSX沸石, 数值模拟