I would appreciate any suggestions or help from people who have experience with washing biodiesel by using a pump. I have tried unsuccessfully to do it and have ended up with about 50% mayonnaise.
Here's what I did: I heated the used oil, which was over a year old, to 130 degrees centigrade for over an hour to make sure there was no water present. I then took a sample and allowed it to cool before titrating it. I got a titration reading of around 2.7. I did the titration three times and it was always around this figure. I added 4 grams to this figure and made a few one litre test batches mixing 6.7 grams of lye to the methanol. I used 22% methanol (220 ml) in order to ensure a complete reaction. I made sure that the lye mixed completely with the methanol. When I mixed the methoxide with the wvo I got a very good separation and everything seemed fine. I then siphoned off the top layer of biodiesel and added an equal amount of water to it. I shook it about 15 times and I got a good separation within seconds and after maybe an hour I had almost completely clean biodiesel on top and white coloured water underneath. There was no middle layer. After a few days I siphoned off the washed biodiesel and washed it a few more times. Same result, perfect separation after a few hours and it separated quite quickly initially. I will call this sample "A". I then took another litre sample of the unwashed biodiesel and ran it through the whole process again to see if I had a complete reaction. I titrated it but it immediately turned purple so I used the figure of 4 grams of lye to mix with the 220 ml of methanol. I mixed the methoxide and biodiesel thoroughly and was pleased to see that I got no separation, indicating that there had been a complete reaction the first time. I washed it again and got good separation very quickly. So far so good. I felt confident enough now to do my first large batch in my processor. By large I mean 50 litres. My processor is an old discarded plastic tractor mounted spray tank. It is rectangular in shape but has a slight cone shaped bottom. I use a pump mixer to pump the contents from the bottom of the tank to the top where I have a three quarter inch pipe connected to a wand which has about 40 small holes drilled to enable good mixing. This wand is submerged near he bottom of the tank. The pump is a sliding vane type and is powered by a 2 horsepower motor running at 1750 rpm. I heated the wvo in a separate heater tank using a butane burner and brought it up to 65 degrees centigrade. I then transferred it by pump to the reaction vessel and turned on my pump. I then gradually added the methoxide mixture (at room temp) to the pump inlet and mixed away for about an hour to ensure good mixing. I have the reactor tank well insulated so the temperature didn't drop below 55 degrees centigrade during the reaction time of one hour. Next morning I saw that everything went very well. I had good separation and the glycerine had fallen to the bottom and was liquid, just as the trial batches had been, so it was easy to draw off the glycerine. I drew off a pint of biodiesel and did the wash test by shaking it vigorously for about ten shakes. I got good separation almost immediately and it cleared to lovely biodiesel and milky water in a few minutes. I drained off the water and let the biodiesel air dry for a few days when it turned the nice clear straw yellow. Call this sample "B". I was happy that I had made good biodiesel so I decided to pump wash the biodiesel in the reaction vessel. I added to the approximately 50 litres of biodiesel about 30 litres of water and circulated it through the processor for about half an hour. The result was mayonnaise. I let it settle for a day and then drained off the milky white water. The only problem was that before long I realised that most of the mixture was at this stage mayonnaise so I stopped draining off the lower layer. What was left of the mixture(about 20 litres) I put into a plastic carboy and went on holidays for a week. When I came back I had three layers; the top 30 percent was biodiesel, a large middle layer of mayonnaise about 60 per cent and a bottom layer of slightly darker mayonnaise. I then went back to my two samples "A" and "B" which I was happy was good biodiesel and performed the wash test on them yet again but this time very vigorously and for about five minutes each. I was trying to simulate the mixing that occurred in the pump mixing. No matter how hard I shook I still got good separation on BOTH samples. It would seem to me that the initial wash has got to be quite gentle even with well made biodiesel and that subsequent washes can then be as violent as you like and you will still get good separation. Before I try another batch I would appreciate any comments from anybody who has tried this washing method. I'm obviously doing something wrong or else pump mixing doesn't work. Sorry for being so long winded but I think in order to get good advice you need as complete a picture of what I did as possible. Regards Dermot ------------------------ Yahoo! Groups Sponsor --------------------~--> $9.95 domain names from Yahoo!. Register anything. http://us.click.yahoo.com/J8kdrA/y20IAA/yQLSAA/FGYolB/TM --------------------------------------------------------------------~-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://infoarchive.net/sgroup/biofuel/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/biofuel/ <*> 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/
