Advanced Separations, Including Distillation, Using Microchannel Architecture for Process Intensification
Special Symposium - EPIC-1: European Process Intensification Conference - 1
EPIC-1: Intensified Hydrodynamics & Structured Environments (IHSE-1)
Keywords: Separations, Distillation, Microchannel
Microchannel reactors and heat exchangers have been demonstrated to bring significant processing advantages, including reduced capital and operating costs, increased product purity, reduced environmental impact, and improved safety. The enhanced heat and mass transfer demonstrated for microreactors may also be exploited for chemical separations. Intensification of both reaction and product purification steps may provide significant benefit for the overall chemical process flowsheet. Since the 1990s, laboratory development in microchannel separation systems has included absorption, adsorption, liquid-liquid extraction, distillation and phase separation (TeGrotenhuis et al. 1999, Palo et al. 2006). This paper will focus on the development of a microchannel multistage distillation process.
The technology for separating liquid-liquid mixtures via distillation has been practiced for literally thousands of years, yet it remains a highly energy-intensive, although ubiquitous unit operation for performing chemical separations. Over the past several decades, new distillation column, tray, and packing designs have yielded incrementally improved efficiency, while larger improvements have remained elusive. Microchannel architecture permits a radically new approach to distillation; one that has the potential to provide a step change improvement in energy consumption as well as lower capital costs and other process advantages.
Microchannel distillation technology enhances mass transfer by contacting thin vapor and liquid films in very small channels, dramatically reducing the Height-to-an-Equivalent Theoretical Plate (HETP), from more than 25 cm to less than 5 cm. Microchannel architecture also allows temperature profiles to be tightly controlled along the length of the channels using adjacent heat exchange channels integrated in the separation hardware. Enhancements in both mass transfer and heat integration enable dramatically improved performance and new process flow sheet options which were previously seen as commercially unattractive. Microchannel technology is scaled to commercial plant capacities by increasing the numbers of parallel channels conducting identical processes. Techniques for design and fabrication of scaled-up microchannel processing hardware have been developed for a range of large-scale microchannel processing applications.
An example of a close-boiling separation, for hexane and cyclohexane, with an HETP less than 1 cm was demonstrated. The exciting experimental results were also validated theoretically.
References:
TeGrotenhuis WE, RJ Cameron, MG Butcher, PM Martin, and RS Wegeng. 1999. "Microchannel Devices for Efficient Contact of Liquids in Solvent Extraction." Separation Science and Technology 34(6-7):951-974.
Palo, D, V. Stenkamp, R. Dagle, and G. Jovanovic. “Industrial Applications of Microchannel Process Technology in the United States.” Micro Process Engineering. Ed. Brand, Fedder, Hierold, Korvink, Tabata. Advanced Micro & Nanosystems. Weinheim, Germany: Wiley, 2006. 387-414.
Presented Wednesday 19, 11:20 to 11:40, in session EPIC-1: Intensified Hydrodynamics & Structured Environments (IHSE-1).
