Origin of Reflux

As you read the subsequent chapters in this book, please recall the picture of the vodka still. Keep in mind that the origin of the reflux is the vapor generated from burning firewood beneath the big can. This concept is the key to understanding how distillation towers function. You cannot have more reflux without increasing your reboiler duty, unless you are willing to sacrifice the overhead product yield. And if extra reflux results in more heavy components in the overhead, the trays are flooding. 

I have seen a working example of the first continuous distillation column in an apple orchard in southern England. It has a reboiler, feed preheater, reflux condenser, and four bubble cap distillation trays. The column produces apple brandy. We purchased a bottle of brandy from this orchard in 1996, but it remains unopened. Whenever I suggest that we open the bottle, Liz accuses me of trying to become an alcoholic. 

Many of the terms used in this text are defined in the following chapter. Otherwise, the first time we have used a new technical term, we have tried to show the term in italics, which is then defined at the back of the text in the Glossary. A lot of my problems as a young engineer were a result of my not being able to understand the vocabulary used in the process and refining industry. We have tried to address this problem in the Glossary and in Chap. 2. 

---