Can you bubble dried biodiesel to remove excess methanol???

[Bio-boy]

Is it possible to process, water wash, dry & then bubble for a few hours to remove any residual methanol or can bubbling only be done whilst water washing?

[Julian]

I hope it works or I'll look even more stupid than normal.  Apart from demething, it's exactly what I do and have done, on and off, for 8+ years!

[Chug]

If you water wash then dry, then your fuel is ready to filter and use,
the methanol will be removed with the water there will be no residual meth left to bubble.

I think you are confusing demeth and bubble of residual meth and settle the soap out
with water bubbles washing soap and methanol out

[Bio-boy]

The only reason I ask is sometimes I get to the point whilst washing where the water is still unclear yet there is no soap evident. Hence, my thoughts are that there is simply just methanol still in the mix. So could I dry and then bubble over night to remove the methanol. Its no big deal but it would simply remove the need for additional water washes and therefore reduce costs
.

[Julian]

If you water wash then dry, then your fuel is ready to filter and use,
the methanol will be removed with the water there will be no residual meth left to bubble.

I think you are confusing demeth and bubble of residual meth and settle the soap out
with water bubbles washing soap and methanol out

As methanol and water are miscible, if you don't demeth and depending on the method of drying I recon there could still be a mix of methanol and water remaining.  However you certainly won't have any free methanol.

[Chug]

The only reason I ask is sometimes I get to the point whilst washing where the water is still unclear yet there is no soap evident. Hence, my thoughts are that there is simply just methanol still in the mix. So could I dry and then bubble over night to remove the methanol. Its no big deal but it would simply remove the need for additional water washes and therefore reduce costs
.

it could be monoglycerides casing cloudy water, take a small sample and heat it on your cooker to 80-90 degrees, if its meth causing the problem it will be driven off with heat and then see if it washes clear.

[Bio-boy]

I usually water wash until water is crystal clear and all soap has been removed. I then dry using a spray bar.

[Chug]

If you water wash then dry, then your fuel is ready to filter and use,
the methanol will be removed with the water there will be no residual meth left to bubble.

I think you are confusing demeth and bubble of residual meth and settle the soap out
with water bubbles washing soap and methanol out

As methanol and water are miscible, if you don't demeth and depending on the method of drying I recon there could still be a mix of methanol and water remaining.  However you certainly won't have any free methanol.

sorry you've lost me there Julian,

if its washed (properly) then the meth will be gone, if its dried (properly) then the water will be gone, how can you have a mix of water and meth remaining?

[dgs]

Bio Boy,
if you are going to go to the point of bubbling after you have water washed and dried, use the bubbling as the de-meth stage. I realise most people don't de-meth if they are going to water wash, but doing this will result in 'crude bio' that is so low in soap that you can really go to town with your water washing which is either pump wash or compressor wash. If you do this your wash water will be totally clear after a few washes.

I'm pretty sure the cloudyness you find is not monoglycerides( sorry chug, just my opinion)

I've come across this problem before with bubbling. Once you have cracked the agressive water wash method I will guarantee you will never go back to piddling around with bubbles.

[Chug]

don't be sorry Dave, I might be wrong, I aint water washed for many years

[Head Womble]

For those that wish to reduce the amount of washes they do, try adding some acetone to your wash water.
Using acetone I can normally get away with just two pump washes, without it it's 3 or 4 washes.

I do 180L batches and prewash with the second stage gly (20L of water),
then drain the gly/water and add 50L of water with 60ml of acetone, pump for 10 mins, settle and drain, repeat for second wash.

I did some testing a few years ago, doing soap tests at each stage.
I found that the bio that had two acetone washes had less soap than the bio that had had four normal washes.
These tests were done by splitting my normal batch in half, so both tests used the same batch.

I did this with two or three batches, they all had similar results.

I don't have the exact results any more (or I'd post them up), and don't have time to replicate the tests again.

Also the best way of speeding up your washing is to make sure you get a crystal clear 90/10 pass.

[dgs]

Thats interesting stuff, Womble.

After I've de-methed it depends how long I leave it to settle before water washing re soap levels. Overnight will be 2 to 300ppm. 3 days will be <100ppm. Sometimes if I feel the soap is too high I wash with pure glycerine which brings the soap down to 10 to 50ppm.

I compressor wash @ 4 times using only 8 litres of water per wash (200 litre batch) so how much acetone to add to 8 litres of wash water.

[Head Womble]

Thats interesting stuff, Womble.

After I've de-methed it depends how long I leave it to settle before water washing re soap levels. Overnight will be 2 to 300ppm. 3 days will be <100ppm. Sometimes if I feel the soap is too high I wash with pure glycerine which brings the soap down to 10 to 50ppm.

I compressor wash @ 4 times using only 8 litres of water per wash (200 litre batch) so how much acetone to add to 8 litres of wash water.

I have no idea of dosage for your method, but I did find that adding more acetone didn't increase it's effect.

You'll have to do some testing of your own and post the results.

On a side note I hope you have plenty of ventilation when bubbling so aggressively.   

[dgs]

The bio room has 2x doors. Both are open during de-mething, only the odd goose walks in during this stage of the operation. I can tell if this has happened as there will be a present for me on the floor!

[Head Womble]

The bio room has 2x doors. Both are open during de-mething, only the odd goose walks in during this stage of the operation. I can tell if this has happened as there will be a present for me on the floor!

You know what we're like, we have to ask these questions just in case.