----- Original Message ----- From: Keith Addison <[EMAIL PROTECTED]>
> Hello again Paul > > I tried slaked lime to remove FFAs as you suggested. The filtering is > a pain, and the result wasn't very good. It did take out some FFA, > but it didn't neutralize the oil, though I used an excess. I didn't > titrate it afterwards, maybe I should have, but that would have been > yet another step, and I think I'd have been titrating residual lime > as much as anything. Unless I'd washed it out, which might not have > been too effective, and yet another step. Whatever, it didn't reduce > the FFA sufficiently - I tried to transesterify it with the basic > amount of lye, 3.5 gm/litre, but it wasn't nearly enough. I didn't > continue with it after that to find out how much would have been > enough, didn't seem to be any point, but I reckon it would have > needed twice that much or more. Keith, looking back through my records I see that I used a mixing time of about 1 hour. Agree that filtering could be a problem. Details below. BATCH #1013 Date 22-01-02 AIM To determine the potential for neutralisation of FFA in WVO using Calcium hydroxide (lime). BACKGROUND. FFA react with NaOH to form soap. This can cause wash problems and reduced yield with WVO high in FFA. When reacted with Ca(OH)2 FFA will form "soap scum", which is insoluble in the Wash water. FEEDSTOCK Reward WVO, well used very dark. Titration 140 drops =9.3ml of 1% NaOH METHOXIDE nil REACTION VESSEL 2L beaker, PROCESSING 1L of oil heated to 120 deg C. Neutralisation of the FFA would have required 9.3g NaOH/Litre WVO. 9.3g NaOH is equivalent to 8.6g Ca(OH)2 10g Ca(OH)2 mixed to a slurry and added to hot oil. Stirrer /hotplate used. Small pellet (only one available). Set at almost full speed. Temperature maintained at 100 deg C for 1 hour. REACTION PROGRESS WVO clear but dark brown. When lime slurry added there was some froathing as it was stirred in. (briskly incorporated with thermometer.) WVO + lime at 100 deg C clear dark liquid. Small ammount of material sticking to bottom of beaker, slightly tacky, stirred back in using thermometer. Cooled to 30 deg for acidity testing, solution turned murky and viscous somewhere above 50 degrees. Appearance of a pale gravey. Acidity "gravey' <15 drops (added in 5 drop lots). Filtered gravey 13 drops (more accurate) GLYCERINE UNWASHED BD WASHING FILTERING CONCLUSION The Level of FFA in WVO can be substantially reduced by the addition of lime and stirring at a temperature of 100 deg C for 1 hour. FOLLOWUP. Try to achieve the same effect at lower temp/time levels. Copyright Paul Gobert 2001. > > The caustic refining step is much simpler - no heating, no filtering, > nothing extra - and it works well. Also I reckon the soapstock is > useful, but I don't think the deposit the lime leaves you with is > useful. I fine-tuned the caustic refining step a bit and got 80% > production from oil titrating at 9.15 ml. I can only get 75% > production from that oil with a single-stage base process, and this > is much easier. It's a lot quicker and simpler than acid-base - > though again acid-base gives higher production and uses less lye. But > lye's cheap, and 80% is okay for dirty oil like this. > > Terry suggested CaO, quicklime, which is not easy to come by these > days, though I do have some. Maybe I'll give it a try. But actually > I'm quite satisfied with this caustic refining step - what Michael > more correctly called saponification-transesterification. Definitely > preferable to single-stage base for high-FFA oils, and a useful > alternative to acid-base. > > Best wishes > > Keith > Given the FFA level of your oil I think that you are doing very well to get such high yields. Regards, Paul Gobert. ------------------------ Yahoo! Groups Sponsor ---------------------~--> Sell a Home with Ease! http://us.click.yahoo.com/SrPZMC/kTmEAA/MVfIAA/9bTolB/TM ---------------------------------------------------------------------~-> Biofuels at Journey to Forever http://journeytoforever.org/biofuel.html Biofuel at WebConX http://www.webconx.dns2go.com/2000/biofuel/biofuel.htm List messages are archived at the Info-Archive at NNYTech: http://archive.nnytech.net/ To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
