Energy-saving Integrated Technologies For Recovery And Dehydration Of Bioethanol

In the bio-based fuel ethanol production process, the recovery and dehydration consume the largest energy. This paper focuses on the recovery and dehydration of bioethanol, and all the technology options are compared and evaluated by means of chemical process simulation software tools. Then several energy-saving hybrid technologies are developed on that basis.After comparing the recovery technology options including distillation or double-effect distillation, steam striping, inert gas striping, extraction, hydrophobic zeolite adsorption and pervaporation, the result shows that the traditional distillation method has insurmountable advantage in this process, while others have one or more shortcomings below: high energy consumption, process complexity, operational instability problems, high cost of equipment investment, etc.After comparing the dehydration technology options including hydrophilic molecular sieve adsorption, azeotropic distillation, extractive distillation, pervaporation and vapor permeation, the result shows that hydrophilic molecular sieve adsorption is the most mature technology, and large-scale industrialization has been achieved. But there are defects including high regeneration energy consumption, operational complexity, etc. The energy consumption of azeotropic distillation and extractive distillation is huge and both of them need a third component, so they has rarely been used now. The pervaporation and vapor permeation technology based on membrane has the most energy-saving advantages, at the same time the equipment is simple and easy to operate.Three kinds of new hybrid processes A, B, C are proposed based on the combinatorial optimization of a variety of the recovery and dehydration technology options. All of the new processes are compared with the traditional distillation-adsorption system, and the result shows that distillation-vapor permeation system has remarkable energy saving effect and application advantage, and are likely near-term alternatives to traditional recovery and dehydration technologies for bioethanol.