Improved Adsorption Processes for Dehydration of Alcohol – US Patent
Ethanol plants are under constant pressure to increase efficiency while minimizing operational costs. As such, alcohol dehydration processes are rapidly gaining popularity among many ethanol manufacturers as a viable solution to reduce the energy consumption associated with conventional distillation. Thermal Kinetics has further improved on the molecular sieve dehydration technology by developing a proprietary modification to the standard two- and three-bed sieve systems. One of the primary features of the patent includes reversing the flow of 190 proof feed vapor to be used for depressurizing, regenerating, and re-pressurizing sieve beds. Additionally, the beds are regenerated to higher vacuum levels with an enhanced 200 proof sweep cycle. This allows for more effective use of the sieve beds, which can significantly increase the overall efficiency and yield of the ethanol dehydration process.
What is Dehydration of Alcohol?
For ethanol to be usable in many applications, industrial specifications require that almost all water and yeast solids be removed. The resulting solution, which is close to 100% pure alcohol, is referred to as dehydrated, absolute, or anhydrous ethanol.
After fermentation, the resulting mash (which consists of ground corn, water, and enzymes) is heated until the ethanol evaporates. This vapor is collected and condensed into a liquid while the majority of water and solids remain behind. This process, known as distillation, separates the ethanol; However, its composition is limited to just 95-96% purity.
It is not possible to remove the remaining water from the mixture through further distillation as the ethyl alcohol forms a constant boiling point mixture with the water; This solution is known as an azeotrope. To achieve pure anhydrous alcohol, the remaining water must be extracted from the alcohol through further dehydration processes.
One of the most popular separation methods used in many ethanol processing plants is molecular sieve dehydration, which employs molecular sieve beds; Each bed has small uniform pores. When the water-ethanol azeotrope mixture comes into contact with the sieve, the water molecules fit into the pores and become adsorbed while allowing the pure ethanol to flow freely.
Once the beds are saturated, the water is released from the sieve by manipulating the temperature or pressure through a process known as regeneration.
Industries That Use Dehydrated Alcohol
Because the removal of water from ethanol is ideal for blending with gasoline, it comes as no surprise that the largest consumer of anhydrous ethanol is the oil and gas/fuel ethanol industry. The addition of ethanol to gas helps reduce vehicle exhaust emissions, which, in turn, decreases the release of greenhouse gases such as carbon dioxide and carbon monoxide into the atmosphere.
Anhydrous ethanol is miscible in almost all ratios with gasoline, making it more suitable for this application than hydrous ethanol. When used purely as a fuel, anhydrous ethanol is considered to be a form of renewable energy and is an excellent clean-burning alternative to fossil fuels.
Dehydrated alcohol is also used extensively in the medical industry. Prescription alcohol (at least 98% ethanol by volume) is injected into nearby nerve tissues to relieve symptoms of chronic pain. Anhydrous ethanol is also used for therapeutic neurolysis of nerves or ganglia in the treatment of certain cancers and trigeminal neuralgia.
The specialty chemical industry also frequently employs dehydrated alcohol, most notably in synthetic organic reactions due to its low toxicity and ability to dissolve non-polar substances.
Key Elements of Thermal Kinetics’ Patent
The unique system Thermal Kinetics developed includes several innovations on conventional molecular sieve ethanol dehydration systems. One of the critical features of the patent is the ability to operate at considerably lower pressures. Pilot runs have shown successful adsorption rates with pressures as low as 18 psia.
Lower operating pressures have several benefits to the dehydration process. First, when combined with modified purge sequences, decreased pressures can significantly improve bed regeneration process and bed drying capacity. More effective regeneration cycles ultimately lead to increased 200 proof ethanol yields and a reduction in regenerate solution recycled to distillation.
Second, lower operating pressures allow for decreased vaporization temperatures. This allows for the usage of waste process heat and a reduction in boiled steam, resulting in significant operating cost savings.
The patent also details enhanced interfacing with existing distillation processes through reduced regenerate recycling and more consistent regenerate return flow rates. As an added benefit, downward pressurization also increases regeneration rates and provides additional protection against bed lift.
More Information from Thermal Kinetics
Thermal Kinetics’ latest patent is poised to revolutionize molecular sieve dehydration systems and improve both the yield and profits of ethanol manufacturers. To learn more about our patented system, contact us today.