but a mere drum isn't going to hold much vacuum
Do you mean it cant maintain a vacuum or physically cant support a vacuum? Appropriate gaskets would be used and the bolts would be of a heavy gauge and could be tightened considerably with long wrenches. Additionally id guess that all seams could be greased over to assure a seal. If the structure couldn't support a high vacuum - well, one that could would be used.
For starters, you might want to study alcohol fuel production, literature should be available in a local library
With intention for starting some informative discussion in this thread can you expand on this? What aspect of fuel production would be helpful to look at when considering a project like this?
http://www.gea-jetpumps.de/produkt/vakuumsysteme/vakuum_allg.jpg (http://www.gea-jetpumps.de/produkt/vakuumsysteme/vakuum_allg.jpg)
Also, as it was pointed out before in this thread, a steam source would run thousands of dollars on top of cost of the aspirator equipment,Post 107852 (missing)
(psyloxy: "Re: Info Request - Lost Archives", Methods Discourse) Eleusis gives a method for the solvent extraction of terpenes followed with subsequent vacuum distillation. Also on the topic of terpenes, Masaki Sato, Motonobu Goto and Tsutomu Hirose,"Supercritical Fluid Extraction on Semibatch Mode for the Removal of Terpene in Citrus Oil" Ind. Eng. Chem. Res., 35, 6, 1906-1911, 1996Post 253541 (missing)
(Rhodium: "Re: Sassy distillation problem", Newbee Forum), "the outdated practice of using a fine capillary for the introduction of air".