Winter Biodiesel.

[dgs]

Just had a look at RickDaTech's 'make biodiesel' site as he has just updated his winter biodiesel section.

This maybe explains why I have found that water washed biodiesel with the monoglyceride layer emulsified and removed doesn't mist and gel until a few degrees lower than normal. (another reason not to use acid during the water wash as it will split the mono emulsion and leave the mono's in the mix)

This is the section;

Cold Soak Filtration Test

As far back as 1995, homebrewers were noticing that when b100 froze and then thawed out, not all of the biodiesel would go back into solution. We found it had to be heated and mixed, sometimes up to 120F to get the "Dreaded White Stuff" to go back into solution with the biodiesel. The Dreaded White stuff would plug filters and strand home brewers if not detected before it was used.

The commercial biodiesel world ran into this problem when Minnesota mandated a 5% biodiesel blend. That winter, trucking companies started reporting excessive plugged fuel filters. In the months and years that followed extensive research was conducted to determine what was causing the filters to plug and how to prevent it. What they found was that under certain conditions, filter plugging precipitants could be formed above the Cloud Point temperature. The latest research indicates Saturated MonoGlycerides as the most likely cause of that filter plugging. When biodiesel is chilled, the saturated monoglycerides can form crystals above the Cloud Point. After light warming, these crystals then change form to a more stable, less soluble crystal, rather than dissolving back into solution. As a direct result of the filter plugging in Minnesota, the Cold Soak Filtration Test was developed to detect this problem before it left the plant.lugging in Minnesota.

The Cold Soak Filtration Test calls for chilling a sample of biodiesel to 40F and holding it there for 16 hours. It is then allowed to warm up to room temperature without heating or stirring the sample. Then the sample is passed through a filter. A 300ml sample must pass through a filter using vacuum in under 360 seconds to pass. At least one study has shown that biodiesel that took less than 200 seconds to pass sample did not experience filter plugging. Biodiesel that took longer than 200 seconds started plugging filters at temperatures above that predicted by its Cloud Point.

[neisel]

I've only ever water washed so can't compare it with other methods, but I see no reason to use any other method.

Now I've mastered the chemical dosing & do not make soap I never need to use acid & can water wash 160 litres of B100 in 4 washes of about 15 litres each for a crystal clear 50/50 test. I usually do one more smaller ww AFTER I've achieved a clear pass. There's no scientific basis for doing this extra wash other than thinking it'll get any tiny residual amount out.

Using this approach ^^^ over the last 2 winters, and, considering I do not make any from November to about April (when it warms up or I near running out of my winter stockpile) I've had v. good results. My BD, stored outside & without any winterising additives, has never clouded, has zero white dropout (even after sitting for as long as 6 months) & is always good to go.

[dgs]

Sounds good neisel. When you say a small water wash after confirming a clear 10/90 do you mean like a 5% prewash.

I know the norm is to assume that residual oil in the bio will emulsify a water wash (as well as other things) but I don't think that is the case. If we look at a drying proceedure where we heat up the oil, let it settle, then run off the residual water, it sort of proves the two won't bind up and emulsify.

The more likely explanation is that if there is a small residual amount of oil left after the final reaction it is proof that a considerable amount of monoglycerides are still present. It is more likely it is these that are the cause of the emulsion.

'Drum' a member on here did a series of mathmatical examples of the amount of mono's present relative to the amount of triglycerides left. I'll have to look at his oid post again.

[neisel]

I do a 5 - 7% (pretty much whatever will fit into the processor) pre-wash, then the 4 15l water washes. The final small wash of 10 or so litres I'm talking about is after a crystal clear 50 / 50 pass (not after the 10 / 90 conversion test) & the very last thing I do before drying it. All washes are w/ cold water.

[dgs]

Thanks neisel.

I had a look at 'Drums' mathmatical model, it is a little difficult to read but is seems if the oil (tri's) are 0.15% then the mono's are 1.24%.

So if there is a small amount of dropout the mono's are approx 8 times as much!

[nigelb]

My methods are very similar to yours Neisel. The only difference is my final wash is with the bio heated to drying temps and my water washes are 10lt and not 15lt.

I've not seen clouding or dropout in my fuel for years. Sometimes I do winterise with XC40 but very rarely.

I did have a little play with a bit of 96% a few years back to see if it would help with the washes. I can't remember what the results were. Must have been insignificant or I'd have carried on with it.

My fuel passes the 10/90 on most occasions. Sometimes I let a little drop out go.

[dgs]

And what temp is your bio good down to, neisel and Nige.

[julesandtash]

I recently changed the fuel filter on my Audi A4 PD130 after 15K miles (it was on the car when I bought it and only changed it as routine servicing as not showing any issues. That included the changeover from dino to bio.
When I cut it open it was clean inside and not a drop of red/black dropout in the bottom.

I have only been using water washed biodiesel (mist wash followed by four pump washes) so it does seem to be much cleaner finished fuel than other methods
Certainly when I used to demeth and settle I always had dropout in the filters

[neisel]

And what temp is your bio good down to, neisel and Nige.

I can't give you a temperature. I haven't had any issues in 3 or 4 years. It's always stored outside, uncovered, throughout the whole winter.

[nigelb]

I concur with Neisel, Dave. My finished fuel is stored in either 25lt containers or the 200lt drum with the dispensing nozzle....these are stored in my garage which gets feckin' cold. Whatever temps it's got down to over the years I've had no issues. I've had my doorstep samples outside set solid...but who hasn't!! However, fuel dispensed to my tank has always been clear and useable.

I can concur with Jules as well regarding demthed bio. I did have a PD once and demethed a few batches. Stored bio always resulted in floaty white particles on standing which would have got into my tank if I hadn't spotted it, so I went back to what I knew best..water washing.

[RichardP]

When I worked in Germany for a few years I put a 20ltr KTC cubie of bio (I only water wash) outside for a week, temps averaged around -12c, there was no dropout whatsoever, very slight clouding and bit less runny which cleared after bringing it inside. Feedstock was mainly rapeseed.

[dgs]

So there's me saying how I wash out the mono's etc, etc. I got up this morning to find all the cubies of bio left outside had gelled.

Got down to -10 to -12 with us last night. Cars started OK. I've been dosing with coldflow in the cubies that were gelled. Will be a bit colder for us tonight so I'll see what they are like in the morning.

[RichardP]

What was the feedstock? If you hadn't water washed the mono's etc out, it would probably have been in a worse way than it is.

[dgs]

Hi Richard, it was rapeseed but one place I get it from uses it just to fry chips, frozen ones that are blanched in Palm. I think this small amount of contamination was giving me the problem. It has all been treated now.

So easy to get caught out, one night -4 and the next -10 or more. Tonight is going to be colder! This is the 1st time in several years I have had to use additives.