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BACKGROUND: Butanol produced from fermentation has attracted the interest of research groups because its physicochemical properties show several enhancements over bioethanol. Recent studies have proposed alternative methods to separate and purify biobutanol from a fermentation broth. These alternatives offer energy and economic savings; in addition, a reduction in environmental impact is observed. However few studies have analyzed the control properties of the process which involves separation of an acetone-butanol-ethanol (ABE) mixture.

Acetone purification is one of the most critical stages of its production process, because a large amount of energy is required. Due to this high energy consumption, the process turns out to be not very sustainable and not friendly to the environment. In this sense, the development of intensified alternatives that minimize energy consumption in this process is of utmost importance. Besides, the safest possible processes are sought, so it is necessary that the control properties of these novel processes be studied at an early design stage. This work proposes two new intensified systems for the purification of acetone; the intensified schemes are a thermally coupled distillation system with a side rectifier and a Petlyuk arrangement. The results indicate that in this type of systems where interconnection flows are used, the magnitudes of these flows have a direct impact on energy consumption, because lower values of interconnection flows as in the case of the thermally coupled system achieve a reduction, whereas higher values as in the case of the Petlyuk system have a negative impact. As for the control properties, the intensified schemes present better values of the condition number with respect to the conventional design, because the interconnection flows reduce the disturbance of the manipulable variables. On the other hand, if the feed is disturbed, the interconnection flows generate an increase in the disturbance in the system, obtaining that the conventional system presents the best values. Therefore, making a balance between the studied designs and looking for a system that presents the best sustainability indicators, the thermally coupled system obtains the best results with a 25.92% energy saving and CO2 emission reduction with respect to the conventional system and acceptable values for the control and safety indexes.

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