Waxing - a possible cause and solution?

[thewormman]

After having a few problems with waxing as explained here

http://www.biopowered.co.uk/forum/index.php/topic,1585.0/topicseen.html

I have been looking into what maybe causing it and how to prevent it.

I had thought that putting Coldflow into my finished Bio would keep it usable down below 0 °C but was shocked when I had wax forming in the bio that blocked a J cloth within a litre or so being filtered when the temp dropped to 8 °C overnight and about 10 °C during the day, towards the end of September.



Since my wife and kids use the car without me, including trips down country lanes in the evenings I really had to get it sorted so it wouldn't break down on her. So it was off to the tax station again temporarily, focuses the solution finding mind 

My Process:
Liquid oil, rapeseed/soya mix, usually no more than 5% solids, glyc washed, well dried 2 stage ASM non tit, after 2nd stage clear pass on the 10/90 drain 2nd stage glyc and demeth, acid wash with vinegar and 10L of water. Further washes till clear, final filter through a j cloth before a 1micron sock.

So information I had and clues I gathered:

Wax seemed to form when temp drops below 11 °C

Apparently according to Uncleh on VOD who gets the same wax build up, if he does not demeth but just washes he doesnt get it.

I believe Nigelb has stated he doesn't get this wax and he does a water prewash and doesn't recover methanol so methanol is still present.

My first batch that I made some mistakes with had a lot of methanol still in it when I washed it, I still had a jar sample of this and when I stuck it in the fridge at 5 °C there was no wax build up.

It has been mentioned that there are maybe 2 different types of wax/HMPEs that form, one at low temps (0 °C to minuses) and one at higher temps (the wax I had)

So I did some research to try to find something that could be:
Present in bio at below 11C but not when warmer.
Not washed out by just water washing.
Reduced by water washing with methanol present by not demething or by doing a water prewash.

I thought maybe the 'wax' must already be in there and was not being converted to Bio during the process so I looked at what was in the feedstock. Free Fatty acids are present depending on the source of the oil, amounts vary due to the source. These are not really converted very well with alkaline catalyst and what isn't converted usually combines with any water to form soap, hence the need for dry oil, a titration is used to measure the level of ffa's in your feedstock thus allowing you to add the correct weight of catalyst above the chosen base figure. FFA's are then turned into soap when the methoxide is introduced into the reactor.

Obviously soap is formed in the reaction and this is what is washed out once it is completed.

BUT...
When I looked at the types of FFAs typically found in the feedstock there was one that stood out,

Oleic Acid

From Wikipedia http://en.wikipedia.org/wiki/Oleic_acid

Appearance - Pale yellow or brownish yellow oily liquid with lard-like odor
 
Melting point - 13-14 °C

Solubility in water - Insoluble

Solubility in methanol - Soluble

It appears in the following amounts:
The majority of olive oil
20-85% of sunflower oil
37-56% of chicken and turkey fat
44-47% of lard

So in conclusion could some Oleic Acid pass through the bio processing as it:
Doesn't convert well using base catalyst just like all FFAs.
It doesn't turn to soap as it is not soluble in water.
It doesn't show up in the 10/90 test as it is soluble in methanol.
It turns to a yellowish lard/wax below 13 °C and this appears to be what I have?

This may explain why some get this and some don't, it depends on feedstock, amount of olive oil/sunflower oil present, what's cooked in it, etc, etc.  My thinking is that when methanol is present in the bio the Oleic acid is dissolved by it and it is then washed out in the water washes with the methanol. If the bio is demethed the Oleic acid is still contained within the bio as bigger molecules that are not soluble so are not washed out.
Non water washers probably see this at the bottom of their settling drums and it is generically called 'soap'.


I was told to filter oil as I needed it and keep a sample outside so I would know when the wax/HMPEs had formed, trouble with that is if there is a cold spell and the bio is in the car for a few days I'm screwed.
So to solve this I have got a cheap chest freezer for £25 and wired a PID and SSR on it. I've cooled 20 litres of bio down to 0 °C so the wax forms, filtered it through a pillow case to take out the worst of it then through my final filter of J cloth and 1 micron sock.

This is it at 0 °C. That is condensation on the jar the bio is clear.



I let it warm to ambient then cooled it again to 0 °C nothing in it still clear.

Even at -4 °C its getting cloudy but still liquid, I suppose this is the coldflow doing its job.



My finishing process from autumn through to spring now will include cooling the washed bio down to at least 3 °C below the average temp for the time of year before final filtering. This will hopefully mean I will not get caught by any cold snaps or need to fix the car at the side of the road, or rescue the wife.

Many will say don't bother or what I have described is rubbish as what they do completely contradicts what I have said, but when my family is going off in the car I want them to come back safe and I'm a worrier.

This seems to be working for me but others may not agree that is their prerogative.

All I know is if the car broke down she would NEVER let me hear the end of it so I will be doing what seems to work for my bio from now on....

[Head Womble]

Very interesting Dave,
this may explain why two stage non titration in conjunction with WBD produces so much of what we know as HMPE.
If these critters dissolve in methanol then they wont get included in the calculations for the second stage,
this will also explain why we use less meths and catalyst with this method.

So maybe the old two stage titration method is the way to go.

Thinking about it, it also explains why I loose so much bio in the wash stage.

[Chug]

If you have a clear 3/27 then you shouldn't have any unconverted TG's.

Anything precipitating out will be methyl esters with higher melt points.

The only real way to make sure your fuel is gonna work at the temp it's used at is to chill and filter to the same or lower temp, as you say you are now doing, but if it goes much colder than the filtered temp you may find more appearing, it's all dependent on the type and amounts of the different fatty acids making up the feedstock.

[Tony]

From what I've seen I get more waxy fallouts from batches with incomplete conversion.  This kinda ties in with monoglycerides which would get washed out if present - and I thought the consensus was that water washing did help?   That or the wash water is always cold enough to cause earlier waxing - a bit like taking it down below ambient.

Did you read about reprocessing wax (or HMPE as we assumed it was at the time?)

http://www.biopowered.co.uk/forum/index.php/topic,889.0.html

[Head Womble]

From what I've seen I get more waxy fallouts from batches with incomplete conversion.  This kinda ties in with monoglycerides which would get washed out if present - and I thought the consensus was that water washing did help?   That or the wash water is always cold enough to cause earlier waxing - a bit like taking it down below ambient.

Did you read about reprocessing wax (or HMPE as we assumed it was at the time?)

http://www.biopowered.co.uk/forum/index.php/topic,889.0.html

Assuming we all use mains water I can't see how we can get below ambient at the time of year we need it.
Think about it, the mains water is generally a couple of °c off ground temperature.

Tony, today I've been thinking about your overdose method, if wormman is right, and my thoughts on two stage non titration have any founding, then your method should not suffer in the same way.

[Julian]

I've measured my mains water temperature on several occasions in winter and regardless of ambient it seem constant at around 9 -10°C.

[Julian]

From what I've seen I get more waxy fallouts from batches with incomplete conversion.  This kinda ties in with monoglycerides which would get washed out if present - and I thought the consensus was that water washing did help?   That or the wash water is always cold enough to cause earlier waxing - a bit like taking it down below ambient.

Did you read about reprocessing wax (or HMPE as we assumed it was at the time?)

http://www.biopowered.co.uk/forum/index.php/topic,889.0.html

Yes, all the tests I did were pretty conclusive that water washing drastically reduced (what we call) HMPEs ... possibly more so than any of the winterisers. 

[Head Womble]

I've measured my mains water temperature on several occasions in winter and regardless of ambient it seem constant at around 9 -10°C.

I've never measured it, but you've just backed up my thoughts.

[Head Womble]

From what I've seen I get more waxy fallouts from batches with incomplete conversion.  This kinda ties in with monoglycerides which would get washed out if present - and I thought the consensus was that water washing did help?   That or the wash water is always cold enough to cause earlier waxing - a bit like taking it down below ambient.

Did you read about reprocessing wax (or HMPE as we assumed it was at the time?)

http://www.biopowered.co.uk/forum/index.php/topic,889.0.html

Yes, all the tests I did were pretty conclusive that water washing drastically reduced (what we call) HMPEs ... possibly more so than any of the winterisers.

Did these test include batches that had been demethed before washing and batches that weren't ?

[Julian]

From what I've seen I get more waxy fallouts from batches with incomplete conversion.  This kinda ties in with monoglycerides which would get washed out if present - and I thought the consensus was that water washing did help?   That or the wash water is always cold enough to cause earlier waxing - a bit like taking it down below ambient.

Did you read about reprocessing wax (or HMPE as we assumed it was at the time?)

http://www.biopowered.co.uk/forum/index.php/topic,889.0.html

Yes, all the tests I did were pretty conclusive that water washing drastically reduced (what we call) HMPEs ... possibly more so than any of the winterisers.

Did these test include batches that had been demethed before washing and batches that weren't ?

Certainly my bio had been.  Not sure about Keith's and Niges, I suspect some of theirs hadn't from what I know of their processes.

[whatarascal]

If we let these waxes or whatever they are build up,what is the best way to filter "say"a 150 litre batch.
I will probably have to do some tests.
my process is sort of Dry 2 stage demeth.
The waxing will start  at some point near the end of my process," not yet this year i hasten to add"I demeth and don't pre-wash with water then bubble from demeth temp to  30c for 24hrs ,settle for some time.

Its after the heaters are switched off that the flakes start to appear when temps are close to zero or even higher.

I have tried coldflow additives after the 24 hr period and before last of soaps "or whatever"have dropped out.

This has caused a lot of stuff"dont know what "to precipitate out,and freezer tests on the bio have been less than if the coldflow was added after settling for a week.

This stuff sticks around the inside of the drum so it must be sticking to inside of pipes i suppose.

Anyhow if we get these waxes how the bloody ell can we filter them out without blocking filters

[Tony]

I pumped the liquid off the top, leaving the cream at the bottom.  This then gets reprocessed.

Overdose definitely helps but I still do get it when I'm processing some nasty oil and fail to add enough catalyst (3/27 dropout seen).

I still think there are likely several causes of waxing, but I'm pretty convinced monoglycerides are one of the major causes, because with my wax:

- it's soluble in Methanol but cloudy
- attempts to wash a sample creates hell of an emulsion that doesn't easily split
- if reprocessed it turns into liquid bio that doesn't form creams again

[K.H]

I dont demeth before washing, as the water removes the meth i consider it a wasted effort, my wash tank is outside so i assume the bio is pretty cold during winter 

[nigelb]

I'm with Keith and echo his comments.

In my process with no HMPE or Oliec Acid issues I consider the demeth process redundant. A good water washing method has the ability to remove an awful lot of problems. Mind you feedstock, clearly, is a major here as well.

It still surprises me just how difficult some make it.

[whatarascal]

I'm with Keith and echo his comments.

In my process with no HMPE or Oliec Acid issues I consider the demeth process redundant. A good water washing method has the ability to remove an awful lot of problems. Mind you feedstock, clearly, is a major here as well.

It still surprises me just how difficult some make it.

Nige
I think it would be great if you put your process from start to finish on wiki or whatever then we could all benefit from your fountain of knowledge.