Since the beginning of the Helium Shortage 3.0, specialty chemicals group Evonik has seen increasing interest in membranes for helium purification, especially in Canada and the US.
As a result of helium shortages and rising prices in recent years, companies are looking for ways to produce more ‘native’ helium and recover helium consumed during their process.
For any project to be viable, the costs must balance well against the projected revenue, and this has not always been the case for helium production projects, especially for smaller wells.
The conventional helium production process uses a cryogenic unit to separate helium from other constituents such as carbon dioxide, nitrogen, methane, and other hydrocarbons. This works when the scale of gas being processed is large enough, but it is expensive to build and operate.
Membrane separation technology is an alternative method for helium production, and Evonik is a leader in membrane-based separation technologies. Evonik’s SEPURAN® Noble membrane is designed specifically for helium recovery and purification, and separates gases depending on their size and solubility in Evonik’s polyimide fibres. The membrane enables highly pure helium to be efficiently produced, even when inlet concentrations of helium are very low.
How it works
SEPURAN® technology uses customized hollow fibre membranes for efficient gas separation. Biogas upgrading, nitrogen generation and helium recovery are just three of the many applications for SEPURAN® products.
In a separation, such as between helium and methane, permeation of helium through the membrane is much faster than most other gases. The driving force required for the separation is obtained through a partial pressure gradient. With Evonik separation technology, helium recovery of more than 95% is possible.
Membranes are one of Evonik’s innovation growth fields and they are a fully backward-integrated membrane manufacturer. Evonik makes its own polymers which gives it total control over the chemistry. This backward integration enables them to provide quick and effective development of polymers for gas separation.
Membranes offer several advantages over conventional separation technologies, as Pressure Swing Adsorption (PSA) units are complex and cryogenic units are expensive to buy and operate. Designing with cryogenic units often results in helium production projects not being economically viable. But SEPURAN® membrane technology advantages include:
- Much lower operating costs and capital requirements
- Passive system: low/no maintenance, smoother operations
- SEPURAN®’s polyimide fiber is extremely durable and able to withstand upset conditions such as hydrocarbon carryover
- High selectivity leads to high helium yields
When combined with a PSA, membranes can produce >99% helium with >95% yield. This purity is easily marketable and can be produced with a fraction of the required equipment compared to cryogenics. Membranes do the bulk of purification, then a PSA polishes the gas up to final purity. The PSA can be much smaller since the membranes have already accomplished much of the targeted separation.
Purification at work
Evonik collaborated with Linde Engineering to set up a first-of-its-kind helium purification facility using a hybrid process of membrane and PSA technology in Mankota, Canada, four years ago. Linde Engineering built the world’s first plant to recover high-purity helium from nitrogen-rich natural gas without the need for cryogenic technology using Evonik’s membrane technology. Low capital was required for this project compared to cryogenic technologies, yet it still produces 99.999% pure helium.
At the heart of the system are hollow fibres made of high-performance polymers that Evonik embeds in cylindrical stainless steel cartridges. The pre-treated raw gas is fed into the membrane cartridge under high pressure. Small molecules in the gas mixture (for example, helium and hydrogen) and molecules with a high specific rate of diffusion (for example, gaseous water or carbon dioxide) can pass through the membrane faster than larger molecules and leave the membrane module as permeate on the low-pressure side (first exit). Larger molecules such as methane and nitrogen diffuse through the membrane at a much slower rate. As a result, the majority of these leave the hollow fibres again as retentate gas from the module’s second exit (high-pressure side). The technical name for this process is the principle of selective permeation.
Alex Evans, Business Development Manager, Membranes, at Evonik Corporation, told gasworld, “The helium purification plant in Mankota processes more than 250,000 standard cubic meters of crude gas daily and produces industrial quality helium of 99.999% purity. This hybrid membrane/purifier design can deliver Grade A or better helium purities, and does so directly at the well. Purifying helium at the well avoids trucking or pumping around other associated gases from the formation, making the production process much more efficient overall.”
Evonik provides local support with a global presence. The company’s experts travel to assist with plant startups and optimisations and are fully capable of assisting in the execution of a project from early designs to plant startup and beyond. At their technical center near Lafayette, Indiana, they provide a team of technicians as well as test equipment to assist customers with performance quality assessments and troubleshooting.
Typical end uses for helium include the optical fiber industry; medical devices, MRI; leak detection; lifting gas; balloon filling; welding and metal work; electronics industry; oil and gas production; refrigerants, and scuba diving.
Evans added, “In addition to the production of native helium, helium recovery is also experiencing a renaissance. In fibre optic manufacturing, for example, helium becomes contaminated with air and eventually reaches a low enough purity where it is no longer useful. SEPURAN® membranes can capture and repurify the contaminated helium. When combined with Evonik’s patented 3-stage membrane configuration, this allows users to recover >99% of their helium and return the purity to >99%, all with no moving parts.”