Permylene is a patented membrane technology that has significant cost, environmental and other benefits in the production of chemical products derived from petroleum and natural gas. Permylene is currently the only commercially viable, high-performance alternative to traditional distillation techniques for olefin-paraffin separation and olefin purification. The technology is also able to perform commercially valuable separations that have, to date, been considered difficult or impractical.
Permylene membrane technology is suitable for the purification of C2, C3 and C4 olefins (ethylene, propylene and butenes) by separating them from their corresponding paraffins (ethane, propane, and butanes respectively) in mixed gas streams.
Permylene membrane systems can be utilized in olefins production from cracking, olefins recovery and purification from purge or reactor vent streams, on-purpose olefins production, olefins extraction in oil refining and upgrading, and olefin based specialty chemicals production. Permylene membrane systems can be applied in place of distillation, or in a hybrid mode in conjunction with traditional distillation in these applications.
The benefits of using a Permylene membrane system for olefin/paraffin separation are many, and include:
- Lower capital cost (capex) alternative to distillation
- Lower energy costs
- Reduced environmental impact from emissions (GHG)
- Recovery of valuable olefins from waste streams
- Olefin stream value upgrading
- New product opportunities
Permylene uses a natural source polymer facilitated transport membrane designed for industrial conditions. Steady and stable olefin transport is achieved in continuous, non-stop operation via circulation of an aqueous silver nitrate solution over a spiral wound membrane containing a hydrogel coating. The silver ions in the silver nitrate solution within the hydrogel structure form a reversible complex with the double bonds of the olefin molecules. Any molecules not possessing a double bond are rejected, resulting in excellent selectivity. The process is primarily driven by the olefin partial pressure differential across the Permylene membrane resulting in commercially attractive permeation rates.
Constructed of proprietary polymeric materials, the operating temperature range for the Permylene membrane system is between 10℃ and 70℃, making a wide range of practical operating pressures available for various olefin / paraffin separations.
Unlike similar technologies that are in the development stage, Permylene membrane systems can be effectively used over the widest range of olefin/paraffin ratios. Olefin purity in the permeate stream from a Permylene membrane system is typically > 99.5% regardless of the olefin content in the feed stream. Olefin recovery depends in large part on the olefin concentration in the mixed gas feed stream as well as the available partial pressure differential between the mixed gas feed stream and the allowable permeate (product) pressure. The higher the olefin content in the feed stream, the higher the recovery of the olefin possible. The greater the partial pressure differential available between the feed stream and the permeate stream, the higher the recovery of the olefin.
In the Permylene membrane system, the permeate stream absorbs moisture from the silver nitrate hydration maintenance solution and the hydrogel layer as it expands through the membrane , moving from the higher pressure to the lower pressure side. This moisture loss cannot be sufficiently compensated for by humidification of the feed gas prior to entry into the membrane system. As the aqueous silver nitrate solution is continuously circulated across the surface of the membrane concurrently with the hydrocarbon gas flow, the silver nitrate content maintains the charge of silver ions within the membrane while continuously replenishing the moisture lost to the permeating gas stream. The hydration maintenance solution is automatically controlled within a target molarity range using reverse osmosis or deionized water as make up. Because only the water leaves the membrane system in the permeate and retentate streams, the silver ions remain in the membrane and hydration system and are not consumed in the process.
No. The membrane hydration system is a closed circulation system with the only losses being the water that leaves the membrane system in the permeate and retentate streams. There is no silver nitrate solution carryover in the permeate or the retentate streams.
No, the innovative Permylene membrane system design can be employed for any C2, C3 and C4 mixed olefin/paraffin gas stream.
The payback time for a Permylene membrane system is a function of a number of variables including feed stream composition, the desired olefin recovery level, and the available partial pressure differential between the feed gas pressure and the available permeate pressure to name a few. Our experience to date based on numerous candidate stream evaluations would suggest payback times from several months to less than three years.
The spiral wound elements employed in a Permylene membrane system are of a design that is commonly used in applications such as water purification. As such, Imtex estimates the life of the membrane elements to be at least five to seven years, which coincides with the typical timing of petrochemical operation maintenance turnarounds.
Imtex is involved with Permylene membrane system projects from start to finish. Starting with the initial opportunity evaluation, to basic engineering design, process hazard analysis reviews, P&ID reviews, to project installation, commissioning and start-up, Imtex will be involved and will support every aspect of a project.
While no Permylene installations are currently in commercial operation, Imtex is currently working on a number of projects that are in the initial design and plant site demonstration phase. Once demonstrations are completed, and the technology is validated to the customers’ satisfaction, Imtex expects commercial installations to take place.
All you have to do is ask us! The best way to initiate the process is to contact us with basic information on the opportunity to be evaluated. You will be then contacted by a member of the Imtex business development team to proceed with the evaluation. Imtex performs such initial evaluations on a complimentary basis.
Yes. C4 hydrocarbon separations (butenes from butanes) are particularly challenging for distillation due to the boiling point similarity between the C4 species. This makes C4 separations such as 1-butene/iso-butane and 2-butene/n-butane difficult. Permylene’s facilitated transport separation mechanism functions independent of relative volatility, allowing these separations to be easily achieved. Permylene membrane separation technology can replace and/or integrate with traditional C4 distillation and result in a more cost effective and operationally efficient system. Contact us to discuss your specific application and objectives.
Yes, Imtex has been asked to evaluate a number of different ways to integrate Permylene membrane systems into traditional ethylene production processes. Examples include debottlenecking C2 splitter operations, hybrid systems to enhance the purity of C2 splitter overhead streams, and systems to improve splitter efficiency, to name a few. Contact us to learn more.