Abstract:

A novel multistage series gas separation system was proposed according to the molecular exchange flow effect. Meanwhile, a mathematical model describing the separation performance and energy consumption of the proposed system was established using the "pipenet method" and the effective energy (exergy) analysis. Moreover, it was studied that the impact of operating parameters (i.e., temperature difference, Knudsen number and production rate) and the structural parameter (i.e., number of separation units in series) on the evaluation indices of the system performance (i.e., molar concentration and recovery rate of the target component in the final product gas) and energy consumption (i.e., minimum separation work and total energy consumption) when separating Ne-Ar mixtures with the proposed system. The results indicated that the molar concentration and recovery rate of the target component, minimum separation work, and total energy consumption increase with the rise of the temperature difference, and first increased and then decreased with the rise of the Knudsen number. The molar concentration and recovery rate of the target component, minimum separation work and total energy consumption reach the peaks at the Knudsen number approximately equaled to 1.5. With the rise of the production rate and the number of separation units in series, the molar concentration of the target component decreased while the recovery rate increased. The minimum separation work and total energy consumption increased with the rise of the number of separation units in series but decreased with the rise of the production rate. The molar concentration of the target component up to 98.55% can be achieved at the temperature difference of 60K. Just 5 separation units were required to obtain a target component recovery rate of 90.29% at the production rate of 0.1, with the corresponding minimum separation work of 1.56GJ/t Ne and the total energy consumption of 1.62GJ/t Ne. The proposed system was applicable to various gas separation scenarios owing to its modular structure. Additionally, it can directly utilize low-grade thermal energy for cascaded energy utilization, representing an innovative gas separation technology that aligned with the current requirements for green development.

Key words: molecular exchange flow, multistage in series, gas separation, exergy analysis, performance optimization

摘要：

提出了一种基于分子交换流效应的新型串联式多级气体分离系统，采用“管网法”和有效能（㶲）分析法建立了描述其分离性能及能耗的数学模型，并开发了相应算法。以Ne-Ar混合物为分离对象，研究了工况参数温差、努森数和产品率及结构参数分离单元串联级数对分离性能和能耗评价指标终端产品气体中目标组分的摩尔浓度和回收率、最小分离功和总能耗的影响。结果表明，目标组分的摩尔浓度和回收率、最小分离功和总能耗随温差的增大而增大，随努森数的增大先增大后减小，并在努森数约为1.5时取得极大值；目标组分的摩尔浓度随产品率和串联级数的增加而降低，但回收率却与之相反；最小分离功和总能耗随串联级数的增加而增大，但随产品率的增大而降低。该系统在60K温差下可使目标组分的摩尔分数达98.55%；当产品率为0.1时，该系统仅需5级串联即可使目标组分回收率达到90.29%，对应的最小分离功为1.56GJ/t Ne、总能耗为1.62GJ/t Ne。该系统为模块化结构，具有较强的气体分离场景适应性，加之可直接利用低品位热能以实现能量梯级利用，代表了一种符合当今绿色发展要求的新型气体分离技术。

关键词: 分子交换流, 多级串联, 气体分离, ?分析, 性能优化