Usually, all gases can permeate through polymer membranes. The process involves gas molecules first being adsorbed and dissolved on the high-pressure side surface of the membrane, then diffusing through the membrane due to the concentration gradient, and finally desorbing from the low-pressure side of the membrane. Small molecules and molecules with strong polarity (such as water vapor and carbon dioxide) pass through the membrane faster and are concentrated on the permeation side. In contrast, larger molecules and molecules with weak polarity (such as nitrogen) pass through more slowly and are retained on the retentate side, where they are enriched, thus achieving gas mixture separation. Membrane separation utilizes the differing permeation rates of various gases through polymer membranes to achieve gas separation. The driving force for separation is the partial pressure difference across the membrane. Therefore, membrane gas separation involves no phase change and requires no regeneration, offering the advantages of simple equipment and low operation and maintenance costs. A membrane separator (assembly) consists of thousands of hollow fiber separation membranes housed within a shell. Its structure, similar to that of a shell-and-tube heat exchanger, provides the largest separation membrane surface area within the smallest space. Thus, the membrane separation system offers a small footprint, light weight, and high separation efficiency.