We love when drums of the actual feedstock that customers use are sent to us, so we can search for hidden, minute amounts of contaminants, often invisible at first (more ghoulish language)!
The differences between an ideal feedstock upon which the concept design was developed and the real feedstock make-up can affect the path chosen to break the azeotrope, but pilot testing uncovers those trace components and finds solutions.
Breaking azeotropes: Homogeneous and Heterogeneous
Azeotropic distillation experts talk about heterogeneous azeotropes (the simplest ones to break) and homogeneous, when two substances are totally miscible. When the two substances are homogeneous, such as acetonitrile and water, or THF and water, pressure swing distillation can be used; two distillation columns at different pressures will break the azeotrope.
On the other hand, when two substances are heterogeneous azeotropes (substances nonmiscible), a liquid separation agent is often used to form a ternary azeotrope, which then aids in the distillation process. Two examples of heterogeneous azeotropes are n-butanol and water or methylene chloride and water. Keep an eye out for those azeotropes.
Working with non-ideal separations, such as azeotropes, may require multiple distillation columns, and several decades of chemical process design experience. If you are suspicious that an azeotrope might be lurking in your process, chat up one of our representatives at kochmodular.com. No ghosts there; it is manned by real, live chemical engineers!