Glycerin can be defined both chemically and via evaporative/distillation, preferably in a vacuum and using "thin film" methods.
The question that must be answered is, "What is the expected end use of the derived glycerin product?" Should you only require tech grade - ~95% glycerin with an H2O, MeOH, KOH and biodiesel impurity - chemical refinement of bio-diesel derived glycerin is more than sufficient and enormously energy efficient - the sole co-products being three variations of potassium phosphate fertilizer and recovered free fatty acids, the latter of which can be converted back into biodiesel. Given sufficient settling time, the biodiesel impurity is almost negligible (as much as I hate the words "negligible" and "significant"). In processes that utilize glycerin under the open application of heat, such as soap making, the MeOH impurity becomes nearly nil or nil, as it is mostly evaporated. The KOH impurity - assuming it needs to be or can quantified - is simply calculated into those processes that require caustic, such as soap making. Preferably the caustic component is reduced to a level that it need not even be calculated into manufacture. Should you require a glycerin component of cosmetic or food grade, evaporative/distillation techniques under vacuum must be implemented. Such process is enormously energy intensive. For all practical intents and purposes, pot-distillation of glycerin cannot be economically or energy efficiently achieved. The means of preference is "thin-film" evaporation, where continual but small amounts of glycerin are applied to the high surface area of a heated element in order to achieve the highest degree of glycerin exposure in the shortest amount of time. This is the same process that is preferred to recover alcohol as well....dripping thin films of alcohol/glycerin or alcohol//FFAs onto a "hot cylinder" in order to recover the highest percentage of alcohol solvent. The suggestion here is to precipitate all caustic out of the glycerin/MeOH/KOH solution using phosphoric acid and then subjecting the glycerin/MeOH to evaporative distillation to recover the MeOH. Even if ethanol were the alcohol of choice, I would still exercise evaporative/distillation techniques to recover the premium ethanol product. The addition of Portland Cement to the recovered ethanol can return it to anhydrous state suitable again for biodiesel manufacture. Going one step further and subjecting the ~95% tech grade glycerin to "thin film" evaporation requires refined machinery and technique, abundant supply of energy, and a need for higher purity in the first place. Todd Swearingen Appal Energy ----- Original Message ----- From: agroefekta To: biofuel@yahoogroups.com Sent: Tuesday, March 19, 2002 4:39 AM Subject: [biofuel] Can I heat glycerine up to boiling point? I have undestand that glycerine can be refined only by molecular distillation. I have an idea useful for small producers (very cheap and simple) that includes boiling the glycerine up to 360 oC. Shurely, if there happend something like oxidation or pyrolisis, my idea is not usable. But, in other case equipment would be up to 200$ and any source of heat could be used. Equipment is suitable for "make it yourself" production. So, if anyone knows or has got a link to appropriate data base... Thank you! Yahoo! Groups Sponsor ADVERTISEMENT Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Please do NOT send "unsubscribe" messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. ------------------------ Yahoo! Groups Sponsor ---------------------~--> FREE COLLEGE MONEY CLICK HERE to search 600,000 scholarships! http://us.click.yahoo.com/iZp8OC/4m7CAA/ySSFAA/FGYolB/TM ---------------------------------------------------------------------~-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Please do NOT send "unsubscribe" messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
