Fluxxion Metallic Membranes can be used in place of packed columns. They are usually placed in stacks and have no moving parts. Industry needs new low energy separations with enhanced safety and increased flexibility.
A membrane stack can have a 15 cm diameter and a thickness of 0.7 mm. There would be 5 billion identical pores on each membrane with a diameter of 0.45 microns. An individual membrane might have a thickness of 1 micron.
In the case of stripping a solvent from water with air, liquid flows counter current to the air on alternating layers.
Stripping methyl tert-butyl ether (MTBE) from water by nitrogen at ambient conditions was used as a test system for performance evaluation purposes. Inlet concentration of MTBE, different flow rates for liquid and gas were varied in a wide range. The best efficiency was achieved in all cases at lowest liquid flow rate, and tended to decrease progressively with increasing liquid flow rate, i.e. decreasing residence time.
Gas flow rate exhibited practically no effect on separation, indicating that this system can also be considered as fully controlled by liquid side mass transfer resistance. Since the value of the overall liquid side based volumetric mass transfer coefficient was almost constant, the overall height of liquid side transfer unit (HTUoL) increased nearly proportionally and ranged 0.5-4 cm (!). The corresponding heights equivalent to a theoretical plate (HETP values) were 2 to 10 cm (!). These numbers indicate a high mass transfer efficiency, an order of magnitude above that experienced with common types and sizes of corrugated sheet structured packing in similar applications.
Thin Liquid Film Diffusion is the Driving Force
The unique microsieve technology can provide:
- Stable phase separation at miscrosieve surface
- Mass transfer in co-current or counter current stream
- Capillary pressures that stabilize gas-liquid interphase at pores
- Liquid film thickness controllable between 25 and 100 µ
- Pore size controllable between 0.3 and 1.0 µm
- A membrane thickness at 1 µm
Chemical Separation is Important in the Process Industries
- 5% of global energy consumption is in chemicals separations
- 150,000 columns installed world wide
–Aging assets majority constructed in 1960-1980
–Not energy efficient majority designed on oil at $25/bbl
–Rigid assets low flexibility
–Large safety requirements high liquid load inside
Be mindful that the process industries need new low energy separations with enhanced safety and increased flexibility.