SAP values give how many moles of fatty acid are in fresh oil. Even if the oil is used, the moles of fatty acid should remain the same, except, of coarse, for the addition of FREE fatty acid from the food cooked. You just need a little more to add to the Sap determined stoichiometric ratio to account for the additional ffa's. Since I am talking about stoichiometric quantity of fatty acid in the oil, and therefore the MeOH needed, I'd say that Sap determined stoich values are more accurate regardless of the process. It says so in the article that, "it doesn't make much sense anyway if the stoichiometric ratio is wrong in the first place".
By the way, Journey to Forever is great. I've learned so much about biodiesel in the 2 months since I first browsed the site. Christopher -----Original Message----- From: Keith Addison [mailto:[EMAIL PROTECTED] Sent: Saturday, May 24, 2003 1:41 PM To: biofuel@yahoogroups.com Subject: [biofuel] RE: How much methanol should you use? Hello Christopher >I would just like to comment on Christian Lenoir's work regarding the >stoichiometric ratio of methanol to use. His findings are way bellow the >amount that should be use. But that's explained very clearly on that page - that you need the stoichiometric amount PLUS an excess. How much excess you need is also discussed. There's a lot of confusion about this (as also explained there) because some people want to lay down the law on how much methanol is best REGARDLESS of the type and condition of the oil in question, and of the fact that different oils have different stoichiometric ratios. One advantage of doing it this way is that it shows how the different values are arrived at. http://journeytoforever.org/biodiesel_meth.html How much methanol? >I commend his efforts but it would have been >easier and more accurate More accurate? I don't think so. >had he simply used the saponification value of >specific oil instead of going through his trouble. The mole of methanol to >be used would simply be the sap value (which is just the mole of KOH). You >just have to do the conversion. Aleks Kac's 200mL MeOH/Liter is a good all >around ratio for any type of oil, fresh or used. Good if you're doing Aleks's acid-base process, yes, which is why it says at the end: "With the "Foolproof" acid-base two-stage method, don't worry about it, just follow the instructions." But you won't get too far with only 20% if you're trying to use a single-stage method to process, say, coconut oil (only 3.7% meth excess v/v oil? - no way!), or WVO titrating at 10 ml or so. Best Keith >Regards, >Christopher Tan >Philippines Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ 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/ ------------------------ Yahoo! Groups Sponsor ---------------------~--> Get A Free Psychic Reading! Your Online Answer To Life's Important Questions. http://us.click.yahoo.com/Lj3uPC/Me7FAA/CNxFAA/FGYolB/TM ---------------------------------------------------------------------~-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ 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/
