I have been making small batches (20 litres) of bio for a few months now, without any hassels. Now I have a new source of oil and am having problems. I asked th owner about the oil and he assures me that it dosent contain any other products (other that the crud from food). I then thought my titration method was not good, even though it has been working fine, so I made the test solution again and did the titration with the new stuff, same result. Now the oil & testing.
It titrates at 4.5 (NAOH) and I have made several test batches to see what would happen and how different amounts of NAOH would affect the quaity of he end product. I used a base amount of 5 and performed 5 test batches with strange results. I used 240ml meth for each test.
1. Base + 3 NAOH looked as it should with glyc and very little soap, but it didn't pass the 27/3 test.
2. Base + 3.5 as above but with a little more soap than the pervious test, again didn't pass the 27/3 test.
3. Base + 4 same result as above, passed the 27/3 test.
4. Base + 4.5 as above
5. Base + 5 as above, didn't pass 27/3 test.
All the above test were done with the same oil on the same night with the same NAOH & Meth. I did these test because I was getting a high amount of suspended soap in the settled bio. I also used the same test for my used oil from the home chip fryer (titrated at 0.8) and after reacting it, worked as it should, no suspended soap, washed fine passed 27/3, PERFECT. Now why does the other oil have so much suspended soap? I have tried to put the photos here, but no luck. Could someone give me some advice on both these matters. I would like to expand from my 20L processor to the 80L HWS (appleseed/ GL1 day) just to make my life easier and safer and not have the problem I am facing with this oil on a larger scale. It is frustrating having the Dr Pepper method not working and could only imagine the frustration having 80 litres of the same stuff. Some help would be appreciated.

I Don't have any experience reacting with NaoH, But have been told "just don't", KoH makes for a more reliable reaction. Also I have heard of some fryer oils that have an anti frothing agent added to the oil to extend the usable life of the fryer oil, as fryer oil saturated in FFA's will froth when the chips are added. Sorry cant help any more. I would be interested to know what variety of oil the dodgy one is,? or is it a blend.? Is it that frytol stuff that gels to solid when cold? Never had good results with that stuff. What is the restaurant cooking?

Hey Darren
The oil I have been using was cannola blend and it was fine (I cant get it any more as the owner is trying to make bio for his ehicle), but the oil I am getting is, well on the 20 litre drum it says cotton seed oil. There is no wording to say it is a blend and as for the anti frothing agent not sure. The guy cooks the regular stuff from chips & dim sims to scichen strips and snitzel. He tells me that he puts it in the fryer and ater he has finished with it he puts it back into the same tin it came out of. The oil is always liquidy, not like the last stuff I used to get, it also titrates higher (last stuff 2.6 & new stuff 4.7). Again I am not sure why there is all that suspended soap in these test batches, but I can get alot of this oil on a regular basis, and if I cant solve the problem then:
1. I will have to get rid of about 200 litres I have already.
2. Tell the guy to get rid of it himself and
3. find a new supply of oil.
And the way I am going I might not have luck as it took me ages to find this guy. As for KOH, I havent tried samples with it as I am not sure where to get it or what the cost of it is. If can get about 1kg of the stuff I could have a play and see which I prefer. As I said earlier, I have had no real problems with it until now and all previous batches (both 1L ans 20L batches) have worke out fine. Well except for the first few when I started into the world of "non reliance on big oil companies".
I appreciate the response.
Cheers

Quite simply, the higher the FFA count the more catalyst you need to add to neutralise it in a base cataylsed reaction. What also happens in that making biodiesel a molecule of water is given off when the triglyceride (oil) is broken down and bonded to methanol. This molecule of water reacts with FFA and catalyst to form soap as a side reaction .

So the more FFA the more soap which cannot be escaped unless you try a two stage reaction.

Soap should be reomved by washing. It is yet to be proven that it hurts engines in low levels and will just form an ash that the engine should tolerate. If in doubt wash and remove it, above all have fun.

Matt

__________________
Biodiesel Bandit

Landcruiser 98 B100
Peugeot 306 stdt B100
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No1 Chaos,

I take it that you were expecting more soap in your byproduct, due to the higher titration, but not in the biodiesel itself. As you know, the FFA is neutralised into soaps, which we expect to drain off with the by-product.

So we know you will get more soap, but where will the soap be?
Methanol helps the soap stay in solution, so with a high % methanol you will have more soap in solution in the biodiesel, simply because you have more methanol in there.

If you recover methanol from the biodiesel (and also from the byproduct layer - preferrably separately) you will remove the reason for the soap remaining dissolved in the biodiesel and it will then settle out.


Your reaction.
there are 3 main reasons for poor conversion biodiesel:
lack of catalyst, lack of methanol and insufficient time to react (for the reaction temperature)

Water also degrades the reaction as it steals the caustic to make soap from your oil.
If your oil has been tested and found to be free from water then the chouces are:
Methanol - plenty of that. Adds to your costs, but should not degrade the biodiesel.
Caustic. - This may be the issue here. Is it possible that the caustic has degraded?

I accept that your titration is most likely spot on, and your NAOH 5g/L catalyst amount (plus titration amount) should be right, your test batches may not have gone far enough with the added caustic. Perhaps you should have tried catalyst + 6 g/l and catalyst + 7g/l to see where you achieved the 3/27 test results you desire.

If your catalyst has been degraded (was it clumping?) then the catalyst amount may not have been adequate, although the titration amount would have been (fresh titration solution) compensating for any degraded NaOH, but the catalyst portion would not be compensated for any degradation of NaOH. This may be one reason for failing the 3/27 test. Extending the test batches with higher amounts of caustic may have revealed the amount needed to produce biodiesel which passed the 3/27.

I doubt that any antifoaming additive would affect your titration or the reaction. It is added to most liquid oils and it does not seem to affect anyone making biodiesel.

Reaction temperature. - As an experienced biodiesel producer (with more than a few batches from the previous supplier) I am confident that your reaction temperature and time are adequate for the reaction to work.

I hopt this helps,
Tony

Tony
I was actually expecting alot less soap actually. With my own oil (from my deep fryer) I got the same result as the previous batches: ie. yellow bio a thin layer of soap ontop of the glyc and then the glyc, which remains a liquid. The soap layer is virtually non-existant, except that you can see it between the two products. This oil is giving me a solid black layer of glyc (when I heat it is becomes a liquid) then a lighter layer of what I think is glyc, then a layer of soap and then floating or suspended soap. The amount of soap I get depends on how much NAOH I use. With the samples I made:
I have varied the amounts of NAOH but am not sure why I get suspended soap in the unwashed bio. All the previous batches I have made, both new and old oil have resulted in a thin layer of soap and nothing suspended. I will try to put the photos I have of my samples up tomorrow. I understand that my samples might have not gone far enough due to temp etc, but I have not varied anything from before. I had no problems then, well none that I am aware of and to tell you the truth I didn't check some of the other batches with the 27/3 test, but now heaps of soap and no pass on the test. Is this what most people get, or did I get a really clean oil in the begining (titrated at 2 - 2.2). Could you post a pic of your product once it has separated? I would like to see what it looks like, both with the amount/ color of glyc and the amount of soap in the sample.
Cheers
Chaos

When oils gets up around the 5ml NaOH titration level, you run in to processing problems like this when using NaOH. Switch to KOH, it's a lot more forgiving with oils of this nature.

As Matt has said, a small amount of water is made during the reaction and around the 5ml titration level (NaOH), this amount of water starts to become significant and you make more appreciable levels of soap which in turn robs the caustic away from the biodiesel reaction. The soap making reaction takes precedence over the biodiesel reaction.

You may need to use 7, 8, 9g or more of caustic (+ base) to pass the 27/3 test. However with excessive overdosing you run the risk of making of glop. Keep upping the NaOH in your test samples and see what level passes the test.... or makes a litre of jelly.

First step is to check that your oil is totally dry before the reaction, have you done a hot pan test?

If you're getting good separation and the biodiesel washes OK, then I wouldn't get too hung up about passing the 27/3 test. This depends of course on the type of vehicle your putting the fuel into.

If all else fails, use the two stage acid/base method.