Frequently Asked Questions
Siftek™ membranes are filters that allow the separation of water vapor from other vapor compounds in a gas mixture. These membranes are made of a special blend of polymers that have specific morphological and chemical properties. The separation occurs by virtue of a driving force which, in the case of Siftek™, is the steam partial pressure on each side of the membrane.
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The Siftek™ membrane system can replace both distillation columns and molecular sieve units (MSU) in a conventional process. The membrane preferentially permeates water vapor over ethanol molecules exiting the beer column. The fermentation broth is directly fed to the Siftek™ membrane where separation occurs. This results in an ethanol grade of more than 99%. With the Siftek™ membranes, water and ethanol molecules are separated in a matter of seconds.
The production of ethanol in a conventional distillation/dehydration process is energy intensive. Energy is consumed both in the distillation process, including reflux, and during regeneration of the molecular sieve unit (MSU). With the Siftek™ membrane process, the separation occurs in the vapor phase at the surface of the membrane, thus avoiding any requirement for distillation or dehydration. Advanced heat recovery, used in combination with the membrane system, further improves the overall heat balance of the plant.
Siftek™ membrane separation involves a very low rate of product recirculation. Less than 2% of ethanol is recirculated compared to 15-30% for molecular sieves. Overall energy savings range between 40-60%, depending on type of feedstock fermented and beer column operating conditions.
Water/ethanol dehydration simply involves removal of water from the feed at the molecular sieve inlet where the water concentration typically varies between 90-95% by weight. Siftek™ treatment results in an ethanol grade product of more than 99%.
Yes, it is possible. When used to replace molecular sieves, the Siftek™ membrane system can produce potable ethanol because the fusel oils are removed prior to membrane dehydration.
The technology can be applied to any type of biomass feedstock fermentable into sugars. Most frequently fermented feedstocks include corn, sugarcane, wheat, and a variety of cellulosic biomasses that are currently being investigated for ethanol production.
The Siftek™ membrane sustains the entire range of temperatures found in the ethanol industry, from 75°C up to 135°C (approximately 165-250°F) and the corresponding super-heated pressures.
Siftek™ can be advantageously used for the separation of many other blends of water vapor and organic compounds. Here are a few examples: methanol/water, acetic acid/water, air/water, and methane/water.
No fouling is experienced with Siftek™ membranes. Absolutely no chemicals are required. Membranes are replaced after many years of operation.
This system is designed to match the mass flow rate of an alcoholic vapor feed mixture entering the membrane module system. The membrane modules are set in a parallel configuration for every stage of modules installed. There are enough modules installed to achieve the degree of dehydration targeted. Siftek™ modules are standardized in terms of length, diameter, and also overall membrane surface area. The flux of incoming material is consequently constant and system design is facilitated.
The technology proposed by Vaperma is competitive with traditional rectification and molecular sieve solutions. In general, the capital costs involved do not represent a major decision point into the new technology adoption process.
Siftek™ is made of polymers known for their high chemical stability. For example, the membrane will remain stable in presence of a variety of solvents such as methanol, ethanol, and ethyl acetate. It will also remain stable in the presence of organic acids such as acetic and formic acids. Consequently, Siftek™ membranes can be considered over a wide range of industrial applications, with the exception of strong inorganic acids.
