Traditional ethanol dehydration technology:
In industry, vacuum distillation and three-element distillation are traditionally used:
Vacuum distillation method, by changing the position of the azeotropic point, as the degree of vacuum increases, the alcohol concentration gradually increases during distillation.
The three-dimensional distillation method introduces a third component into the original alcohol-water component, such as benzene, ethylene glycol, cyclohexane, etc., among which benzene and ethylene glycol are the most used.
Traditional methods have high energy consumption, and the introduction of some toxic substances will increase cost and safety risks. It is currently recognized internationally that the molecular sieve dehydration method is effective.
Advantages of Molecular Sieve Dehydration Method:
The molecular sieve dehydration method has good effects and mainly has the following advantages:
① The product has high quality and strong dehydration ability. After ethanol dehydration, it can reach a maximum of 99.995% (volume fraction);
② Low energy consumption, without considering the comprehensive energy utilization with other processes, the energy consumption is less than 560KJ/L ethanol;
③ Easy to operate, the whole process can be automatically controlled;
④ Environmentally friendly, no toxic or harmful substances are introduced, and the whole process will not pollute the environment;
⑤ Long life, the service life can reach 5 to 7 years under normal operating conditions.
3A Molecular Sieve Ethanol Dehydration Process:
Molecular sieve dehydration methods are divided into liquid phase dehydration and gas phase dehydration.
Molecular sieve liquid phase dehydration: It can also be called TSA process. Liquid phase dehydration means that the ethanol aqueous solution exists in the form of liquid phase during the entire dehydration process. Liquid phase dehydration requires thermal dehydration regeneration. A typical thermal dehydration system is composed of double beds. Bed A is adsorbed and bed B is regenerated. The adsorption flow time of bed A is 2 to 8 hours. At the same time, bed B achieves the regeneration of molecular sieve through heating, cooling and drainage processes. The molecular sieve of tower B is fed after regeneration, and the molecular sieve of tower A is switched at the same time. regeneration.
During the thermal regeneration process, the bed is usually heated to 230~260°C, and N2 purge is used to bring out the moisture in the system and cool it down.
Molecular sieve gas phase dehydration: It can also be called PSA process. Compared with the thermal liquid phase dehydration process, the gas phase dehydration process using pressure swing regeneration has lower energy consumption and lower cost. It is an advanced ethanol dehydration technology.
The gas phase dehydration process is used to keep the temperature of the system above 140°C. At this time, the water-containing ethanol is completely vaporized, and the vapor enters the PSA device. The dehydration and purification of the ethanol vapor is completed through a series of processes such as equalization, adsorption, equalization, decompression, and desorption. The dehydrated ethanol vapor is condensed and recovered. Compared with the thermal variable device, the pressure variable device has a lower water capacity, and only a small amount of water is removed during the desorption process, so the cycle time is shorter. Xintao 3A molecular sieve produced by our company is a special molecular sieve for alcohol (ethanol) dehydration, which can be used for molecular sieve liquid phase (TSA) and gas phase (PSA) ethanol dehydration and drying.
1. Xintao molecular sieves have large water absorption capacity, high strength, low wear, outstanding advantages in adsorption speed and desorption performance, and have a long service life;
2. Xintao 3A molecular sieves are specially used for dehydration of methanol, ethanol and other polar compounds;
3. Typical packaging: 150kg sealed steel drum, different packaging can be customized according to customer requirements.
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