Does anyone do stir washing?

See the bottom parts of:

http://www.journeytoforever.org/biod...ubblewash.html

Stir washing is more violent but is supposed to work fine if the conversion has taken place properly. The argument against bubble washing is something about the "oxidation" of the BD and also the fact that it masks incomplete reations (which stir washing shows up immediately).

Yes I do stir washing with a model aeroplane propellor mounted on a threaded rod in an electric drill. I have it turning fairly slowly, just so it is mixing not thrashing the bio.I add the water through a shower head. Haven't had emulsion problems. I also do a 5% prewash which makes washing for me very easy. I also washed this way before I started prewashing and had no problems it just took more washes.

Try it and do what you find best for you.

I have been stir washing for many months now. All my batches are 60 litres to date to which I add about 35 litres of water. I wash in 200 litre drums with drainage in the bottom of them. I have plenty of water available from the tank I installed last Christmas. I use one bucket of water straight from the tank (cold) and one bucket of hot water, either from the hot water system, or which I have heated on a gas ring. The temperature of that is about 70 to 80 degrees C.

I stir with a paint stirrer powered by an electric drill. The drill has variable speed and I run it on the slowest possible speed. I have discovered that it is best the keep the stirrer high up in the body of liquid being stirred rather than at the bottom of the tank. In that way I seem to get less (no) problems with emulsification. If I do end up with an emulsion, it is quickly overcome by adding a touch of white vinegar and stirring gently by hand. It all comes good in the second wash! If you want more information, I would be happy to share it with you.

Cheers,
Spanner

Thanks Spanner,

How long do you use the mixer for? How long do you leave to settle between washes?

Thanks for the advice if you can.


Thanks BJ4408,

It seems like we are heading in the same direction. Pre wash then stir wash.

Greetings again.

I pump from the processor to the settling tank where I normally allow the product to sit for 24 hours although it might be as short as overnight if that happens to suit my timetable for the day. I have two taps in the settling tank. The upper one is above the height of the settled glycerol and is therefore the one through which I drain the BD. I have my tanks, all five of them in fact, on steel frames with 3 castors. This gives mobility to each of the tanks and makes it possible to tilt the tank for controlled removal of BD or glycerol.

I pump (95%) finally drain (5%) from the settling tank to the wash tank. It is at that point that I add the water mentioned in my last post. I normally do three or four washes as previously described. I generally stir for 3 or 4 minutes I guess. It is only necessary to stir until the BD is brought into intimate contact with the water. If the BD is still majorly floating on top of the lighter coloured BD/water mix and you see swirls of the lighter colour through the BD, keep on mixing. Be gentle! If your reaction is incomplete for some reason (inaccurate titration, insufficient or poor quality methanol, insufficient processing time, insufficient agitation, incorrect temperature control throughout processing, water in the WVO, etc) you will end up with what one of our friends in the States calls "chicken soup" - or if you like, an emulsion. These definitely increase the processing time!

Timing - I generally allow a longer settling time following the first wash because there are more impurities to be removed and the longer the time, within reason, the better. Having said that, if was a really good reaction and there is no hint of an emulsion having been formed, I might only leave it for 30 minutes before draining off the water (from under!) If an emulsion has formed, then in with maybe 20ml of white vinegar, a slow and gentle hand stir and an overnight settle! Trying to speed up the breaking of an emulsion into too short a time is likely to see too much BD go down the drain. Certainly it is possible to process a good batch on Friday evening for example and complete all the washes on Saturday (substitute other days of the week as appropriate). Drying the BD may take somewhat longer than washing it. The best drying method so far as I am concerned is to leave it in the sun with the entire top of the drum removed so that the sun and the moving air can reach the BD. It ends up being beautiful and a pleasure to use. I am running my car on B100 now that the weather is beginning to warm up a little.

I hope all that is of some assistance to you. I have basically struggled through much of this on my own over the past 15 months or so and I am pleased to assist others where I can. Feel free to come back to me again and again if you think I can help.

See ya,
Spanner

I am including some pix for you 1. PROCESSOR, 2. SETTLING TANK, 3. WASH TANK 4. STIRRER

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