Revolutionary Gas Separation Membrane Technology: Efficient Separation and Flexible Operation for Industrial Advancement

‌Working Principle:

The gas separation membrane system uses a thin film of a polymer (usually polyimide) to selectively “filter” the feed gas for separation. When a mixture of gases passes through the polymer membrane, the differences in the solubility and diffusion coefficients of each gas component in the polymer cause them to permeate the membrane at different rates. This allows gases to be classified as “fast gases” (e.g., H2O, H2, He) and “slow gases” (e.g., N2, CH4, and other hydrocarbons). Under the driving force of the partial pressure difference across the membrane, the faster gases permeate the membrane more quickly and are enriched on the low-pressure permeate side, while the slower gases are retained on the high-pressure side.

A typical membrane separator contains tens of thousands of fibers, sealed at both ends with epoxy resin. The ends of the fiber bundles are cut to expose the fiber pores, allowing gas to move from one end to the other. The fiber bundle is enclosed in a suitable housing that protects the fibers and directs the gas flow correctly.

Gas molecules permeate through the thin walls of the membrane fibers driven by different partial pressures. Factors affecting the permeation rate include solubility, diffusion speed, gas-polymer coordination, and the permeation rates of different gas components. The greater the difference in permeation rates, the better the separation efficiency.

Structure – Hollow Fiber Membrane:

The core component of the membrane separation system is the membrane separator, similar to a shell-and-tube heat exchanger. Tens of thousands of fine hollow fibers are cast into bundles and placed inside a pressure-resistant shell. The mixed gas enters the separator and flows axially along one side of the fibers. The “fast gases” continuously permeate through the membrane walls and are enriched on the other side of the fibers, exiting through the permeate gas outlet. The retained gases exit from the non-permeate gas outlet on the opposite end.

Features:

•  Flexibility: The membrane system offers operational flexibility to accommodate unexpected changes in plans or processes. To increase production, more membrane separators can be added. To reduce production, control valves can be closed to maintain system recovery and purity. Various integration methods can achieve different purities and flow rates from the permeate side.

•  Compact Design: Suitable for small or crowded plants, with minimal on-site installation time, cost, and potential construction errors. The preparation period is short, requiring only simple concrete supports and utilities. The membrane system is skid-mounted for easy mobility.

•  Efficiency and Economy: In most applications, the membrane system has a high recovery rate, with 80-95% efficiency for gases and hydrocarbons. The operating pressure is similar to refining pressure, eliminating the need for additional compression energy. It consumes minimal steam (for temperature control), instrument air, and purge nitrogen. The system is easy to start and stop, and the product gas does not require cooling or pretreatment.

•  Low Maintenance: The membrane separator unit has no moving parts to monitor, maintain, or replace. With proper design, installation, and operating conditions, it is maintenance-free. However, attention should be paid to various operating conditions and tolerable contaminants such as liquid water, ammonia, hydrogen sulfide, hydrocarbons, and aromatics.

•  Long Lifespan: Robust design and construction ensure long service life in petrochemical applications.