The industrial gas separation poses significant challenges to achieve the simultaneous recovery of multiple valuable product gases via a one-stage separation process. To address this issue, we previously introduced the concept of a triple-reflux pressure swing adsorption (TR-PSA) process consisting of three reflux and product streams, which was demonstrated to separate ternary methane (CH₄), nitrogen (N₂), and helium (He) gaseous mixtures using activated carbon. In this work, we have modified the adsorption column packing method from a single uniform adsorbent layer to two distinct layers of adsorbents, aiming to optimize the separation performance of each column section, i.e., the CH₄ enrichment and He purification sections. The adsorbents packed within each bed section are particularly suitable to improve the selectivity and efficiency of each separation section and thus enhance the purity and recovery of three product gases. A nonisothermal dynamic model was built to conduct the parametric studies and to complete the optimization of separation performance by varying the filling height of different adsorbent species in the beds. Results show that the feed gas containing 10% helium, 20% methane, and 70% nitrogen can be enriched to 93.22%, 79.92%, and 96.13%, respectively, via a single-stage layered TR-PSA process. This work provides an effective approach for crude helium purification and methane enrichment from raw natural gas and boil-off gas in the LNG industry.

中文翻译：

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使用分层三重回流变压吸附分离甲烷、氮气和氦气


工业气体分离对通过一步分离工艺实现多种有价值的产品气体的同时回收提出了重大挑战。为了解决这个问题，我们之前介绍了由三个回流和产物流组成的三重回流变压吸附 （TR-PSA） 工艺的概念，该工艺被证明可以使用活性炭分离三元甲烷 （CH₄）、氮气 （N₂） 和氦气 （He） 气态混合物。在这项工作中，我们将吸附柱填充方法从单个均匀吸附层修改为两个不同的吸附剂层，旨在优化每个柱段的分离性能，即 CH₄ 富集段和 He 纯化段。每个床段中填充的吸附剂特别适用于提高每个分离段的选择性和效率，从而提高三种产品气体的纯度和回收率。建立了一个非等温动力学模型来进行参数研究，并通过改变床中不同吸附剂种类的填充高度来完成分离性能的优化。结果表明，通过单级分层 TR-PSA 工艺，含有 10% 氦气、20% 甲烷和 70% 氮气的原料气可分别富集至 93.22%、79.92% 和 96.13%。这项工作为 LNG 行业中原料天然气和蒸发气中的粗氦净化和甲烷富集提供了一种有效的方法。