Abstract:

Pressure swing adsorption (PSA) is a multi-step coupled periodic cycle dynamic process, and the effect of the flow state of the fluid in the adsorption bed on the separation efficiency has not been clarified yet. It is of great guiding significance to deeply explore the concentration field distribution of the fluid in the adsorption bed under different flow conditions through numerical simulation, in order to enhance separation efficiency. In this work, based on Aspen Adsorption V12 a four-bed, nine-step PSA model was established to simulate the separation of dimethyl sulfide /nitrogen, and the effect of the degree of turbulence on the separation efficiency was investigated during the transition process of the mobile phase from layer to turbulence in the adsorption bed. The results showed that when the Reynolds number was in the range of 800—1200, enhanced mobile phase turbulence could effectively improve the separation performance. When the mobile phase changed from transition flow to complete turbulence during PSA adsorption, the dimethyl sulfide was removed from 20μL/L to 8μL/L with the dimethyl sulfide content of 2000μL/L as raw material, and the nitrogen yield decreased from 93.3% to 86.9%. The research results indicated that enhancing turbulence within a certain range should be beneficial to improving the separation efficiency, but excessive flow rates could cause the adsorbent to fluidize, thereby losing effective adsorption and separation capabilities. Therefore, regarding the practical application of PSA process, the turbulence impact on the system should be comprehensively accounted to enhance the separation efficiency.

Key words: pressure swing adsorption, numerical simulation, enhancing fluid perturbation, separation of dimethyl sulfide via adsorption

摘要：

变压吸附（PSA）是一个多步骤耦合的周期性循环动态过程，吸附床层中流体的流动状态对分离效率的影响规律尚不明确，深入探究不同流动状态下吸附床内流体的浓度场分布，对提高分离效率具有重要指导意义。本文基于Aspen Adsorption V12模拟平台，建立了一个描述多组分吸附、混合气体流动传质的四床九步扰动PSA模型，模拟甲硫醚/氮气分离，考察吸附床内流动相由层流向湍流过渡过程中湍动程度对分离效果的影响。结果表明，当雷诺数在800~1200范围内，增强流动相湍动程度可以有效提高分离性能。当PSA吸附过程中流动相由过渡流转变为完全湍流状态时，以甲硫醚含量2000μL/L的氮气为原料，产品气中甲硫醚从20μL/L脱除至8μL/L，氮气收率由93.3%降至86.9%。本研究表明，在一定范围内增强湍动有利于提高分离效果，但流速过高会造成吸附剂流化，从而失去有效的吸附分离能力。因此，PSA工艺实际应用中应综合考虑系统的湍动影响，强化分离效果。

关键词: 变压吸附, 数值模拟, 增强扰动, 甲硫醚吸附分离