How can you extract essential oil from oregano on a large scale?

Answer

Hi Erik
Steam distillation and extraction are usually used to recover such substances from natural products.
In a steam distillation, steam is passed through the raw material. The steam takes with it substances that dissolve in it and is cooled further. Usually the oil then separates from the water.
In an extraction a solvent is added; many organic substances dissolve in it and you will then also have to ensure that you only have the desired component left.
But the most used will probably be the steam distillation, this technique is much more selective than an extraction. If you then look up the definition of essential oil, it is about volatile oils, and it is precisely the volatile substances that you can persuade via a steam distillation. You can find brief descriptions of steam distillation, extraction and also essential oil on wikipedia.

I can’t immediately name a book about the production of those oils, but try books.google.com, and be sure to search for books in English as well.
I don’t know where you are from, but there is a technical encyclopedia, namely Ullmann’s Encyclopedia of Industrial Chemistry, you will probably find more in that. You can find this encyclopedia in the media library of the KHLim in Diepenbeek and the KHBO in Ostend.

Hopefully you can go a little further.