Water washing WVO *before* reacting?

[julianf]

Ive been tempted to do this a number of times, but never gotten around to it...


I currently have the slops from the bottom of my IBC in the reactor.  It went in as gloopy whites, no free water.  I took it up to 80c, and then left it a number of days.  I went past the reactor yesterday, and drew off 20ltrs of black ish water (there's more in there, i just did not have time)


Ive thought -

The water is very grimy.  I wonder what would happen if i then put in, say, 50 ltrs of fresh water (from the tap) and pumped that about hot?  Would it come out clear?  Would it carry out a load of crud?  Would it bring out any water soluble acids?

Could i mist wash WVO for the same result, i wonder?

Or would it all just be a waste of time, considering im going to glyc wash it anyhow?


However, that said, i do remember getting some real grim oil, years back, that needed more than one glyc wash to get it usable.  So, certainly, in that instance, one glyc wash was insufficient to do the job (ie 1-pass did not work 100%)

[dgs]

Unfortunately you will not be able to do this easily. As soon as you start to mix aggressively with the pump the mix will emulsify. You could break it with salt but you will not be able to wash out the ffa's.

However there is a way to do it which (if you also add some catalyst to the wash water) will also neutralise your oil. You have to observe the mix ratio's and mix times otherwise you will produce more soap.

DavidShinn on here has done this many times, it's called caustic stripping.

Have a look; sorry infopop search isn't working at the moment.

OK, here's a brief description. To do this properly ie to yield oil with no titration you need to be able to titrate your oil.

From the titration add the correct amount of NaOH to the correct amount of water. Add the water/catalyst to the oil, mix for 10 mins, then add some glycerol (from memory approx 20 litres for 150 litre batch) Pump for another 15 mins. Leave a few hours to settle, run off wet glycerol. you are left with wet oil which needs drying (probably a double glyc wash would do) but the oil should have no ffa's left.

I will post a link when the infopop search is working again, then you can get the actual amounts  and times required.

I must add I have never done this method as I think the enhanced glyc wash does the same thing without having to dry the oil.

[willbuild]

I've used this method and as Dave points out, time and amounts are very important, get it wrong and you a very thick emulsion that will cause severe blockages.
Tried  3 times 2 were successful , lowered tit from 50 to 25. The one that went wrong   well I don't even want to think about it.
Conclusion I'm sticking to the enhanced glycerol wash for high tit oils.

[dgs]

julianf, I've found the link;

                     http://biodiesel.infopop.cc/eve/forums/a/tpc/f/5367078823/m/3897002473/p/4

[julianf]

I understand about emulsions, however....

When you load a reactor with grotty oil (but no free water) and heat and settle, you get water out.

Therefore, what you loaded with must be an emulsion - which is split using heat and time?

[dgs]

I agree. Yes it does split as it isn't sufficiently emulsified not to do. But you are talking about mixing up the oil with 50 litres of water. Try it and I'm sure you will find it gets really thick and really emulsified.

With the caustic stripping thing you are virtually doing the same thing and also calculating the water/catalyst/glycerol/time so that an emulsion doesn't happen. You just have to then dry the oil.