Dual reflux pressure swing adsorption (DR-PSA) has been regarded as a state-of-the-art adsorption-based process which can simultaneously obtain two streams of pure product gases with a narrow pressure window. However, the DR-PSA has not yet been reported in industrial applications. Herein, a DR-PSA and a heavy-purge pressure vacuum swing adsorption (HP-PVSA) were numerically investigated for the enrichment of 1%, 8% and 15% CH₄ from N₂ gas mixtures in pilot-scale. Key separation indicators such as purity, recovery and energy cost of the two cycles were compared to analyze the limitations of the DR-PSA process while scaling-up. This study reveals the impact of heavy to feed (H/F) ratios on purity and recovery for both cycles and analyses the energy consumption of each process. For feed gas with 15% CH₄, while DR-PSA can achieve a slightly better purity and recovery (88.3% and 88.3%, respectively) compared to HP-PVSA (87.5% and 80.3%, respectively), it also involves an order of magnitude higher energy consumption (181.6 versus 24.6 kJ/mol CH₄ captured). DR-PSA shows significantly superior performance than HP-PVSA when the CH₄ content in the raw feed gas is low. Under the investigated operating conditions, HP-PVSA can only enrich 1% CH₄ to 10% with 78.7% recovery while DR-PSA can obtain 75.3% purity and 77.3% recovery. Results indicate that DR-PSA exhibits superiority in enrichment of dilute gas, however, its high energy consumption, high capital expenditures and limitations in processing high throughput are the chief reasons hindering its industrial application.

中文翻译：

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变压吸附富甲烷中重吹扫和双回流策略的数值比较


双回流变压吸附 （DR-PSA） 被认为是一种最先进的基于吸附的工艺，它可以在较窄的压力窗口内同时获得两股纯产品气体流。然而，DR-PSA 尚未在工业应用中报道。在此，对 DR-PSA 和重吹扫压力真空变摆吸附 （HP-PVSA） 进行了数值研究，以在中试规模中从 N₂ 气体混合物中富集 1%、8% 和 15% CH₄。比较了两个循环的关键分离指标，如纯度、回收率和能源成本，以分析 DR-PSA 工艺在放大时的局限性。本研究揭示了重料比 （H/F） 对两个周期的纯度和回收率的影响，并分析了每个工艺的能耗。对于含 15% CH₄ 的原料气，虽然与 HP-PVSA（分别为 87.5% 和 80.3%）相比，DR-PSA 可以实现略高的纯度和回收率（分别为 88.3% 和 88.3%），但它的能耗也高出一个数量级（捕获的 CH₄ 为 181.6 对 24.6 kJ/mol）。当原料气中的 CH₄ 含量较低时，DR-PSA 的性能明显优于 HP-PVSA。在所研究的操作条件下，HP-PVSA 只能富集 1% CH₄ 至 10%，回收率为 78.7%，而 DR-PSA 可获得 75.3% 的纯度和 77.3% 的回收率。结果表明，DR-PSA 在稀气富集方面表现出优越性，但其高能耗、高资本支出和加工高通量的限制是阻碍其工业应用的主要原因。