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Introduction of Pervaporation Technology |
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- Pervaporation is emerging high tech membrane separation process technology, it is an energy efficient combination of membrane permeation and evaporation and is considered an attractive alternative for many separation processes. The process, which requires only low temperatures and pressures, has obvious cost and performance advantages compared with distillation for azeotropic mixtures.
The principles of the pervaporation process are that the liquid (mixture) is in contact with the membrane. At the permeate side, a partial pressure is generated by means of a vacuum pump. The components of the liquid that move through the membrane are vaporized by the low pressure, removed and condensed.
It had been demonstrated that large energy savings can be achieved by using pervaporation systems as compared to azeotropic distillation of organic mixtures. Besides the energy consuming distillation step, the distillation process requires an entrainer, such as benzene, to break the azeotrope. The removal of this entrainer gives rise to a second distillation, thus increasing energy use and installation costs significantly. Because pervaporation systems make use of more advanced technologies than conventional separation methods, investment costs are considered comparatively lower while operation cost are expected to be even lower than the conventional separation process. Simple pay back times of less than 1 year have been reported for pervaporation installations.
Studies have shown that pervaporation membrane system can offer energy savings of 35% over conventional distillation. In addition the membrane is capable of dehydrating feed to ppm levels of water as well as being resistant to a wide range of aggressive organic solvents.
The MVS Pervaporation membrane modules is flat type module. The modules are made in stainless steel.
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Figure 2 MVS Pervaporation Membrane Module |
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PV for Isopropanol and ETHANOL Dehydration Process |
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IPA and EtOH dehydration are the typical pervaporation application and widely acceptable as most energy effective way to purify IPA and EtOH. The application of MVS pervaporation can be in batch or continuous form. For continuous process, the process can either be used as stand alone system or a hybrid system with conventional distillation.
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The flow diagram of typical stand alone IPA and EtOH dehydration process is shown as following: |
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Figure 3 Flow diagram of MV standard Pervaporation System
The stand alone IPA dehydration is very beneficial to those customers who required for onsite solvent purification and recycle. However, the typical hybrid distillation and pervaporation system is more useful for those customers who manufacture the IPA onside.(See Figure 4 .)
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Figure 4 Flow diagram of MV hybrid Pervaporation System |
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Pervaporation Process Advantages and Benefit |
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MVS Pervaporation system and process technology can be used as an alternative to energy-intensive distillation processes because our pervaporation techniques offer a number of clear advantages over other separation techniques, including: |
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 More cost-effective and thorough separation of azeotropic miscible liquids (liquids composed of components with close boiling points)
No catalyst or entrainers required to affect separation of miscible mixtures
Significant capital cost and operating cost savings over conventional systems
Easy adaptability to hybrid processes.
Small and compact modular installations, easily incorporated into existing production lines
Low running costs;
Simplicity of handling and operation;
No addition of chemicals, no entrainment or absorption, no need for additional separations;
Environmentally friendly and inexpensive upgrading.
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