Water washing vs demething.

[Julian]

Just had another emulsion start whilst washing the last batch along with a minor flood.  Looking on the bright side it gave me an opportunity to wash my very tasteful vinyl flooring.

I always demeth before washing.  I've always demethed and old habits die hard plus my miserly nature tells me it's wrong to waste good Methanol.

Others who don't demeth claim to have never had an emulsion.  So, is it more beneficial to wash with Methanol present?

It's claimed that Methanol holds on to soap and Methanol is miscible in water.  Could this make soap easer to shift?

[K.H]

All i can say is i dont demeth and ive never had an emulsion unless ive fiddled with things,should be easy to test with something like a blender?

[Julian]

The test I was going to do was not demeth the next batch.

Always found not doing something is far easer than doing something!

[K.H]

Sounds good,be interesting to see the result

[Tony]

I'm pretty sure any alcohol prevents formation of emulsions and stops soaps from foaming, which is why jelly batches are recoverable by adding Methanol to return to liquid, then doing glyc/water wash.

Something I noticed a couple of years ago with WBD and water prewash was that it was a lot less forgiving of overdosing the catalyst.  Removing the Methanol made jelly formation much more likely if anything was out.

I don't water prewash at the end of batches now, and haven't for a couple of years precisely for this reason.  The process is forgiving of excess catalyst so long as no water is added - the worst that happens is a little extra soap created from the small amount of water created by mixing the Methoxide in the first place.  You'd probably find with Methylate that you could use a large catalyst excess with no detriment, as there would be no water to cause problems.

That said, and despite being a diehard drywasher, I still believe that water washing gives the best final fuel quality in terms of removing undesirables from the finished product.

[Julian]

Sounds good,be interesting to see the result

Result is rather weird!

Ran a batch as normal with an excellent 3/27 pass which still shows no drop out after a couple of days and a couple of ml of Methanol evaporation.  No 7% pre-wash and no distillation, just settle glycerine and drain.  Then into the wash tank and start to wash.  Only did a couple of hours whilst hot as I was going out that evening.  Have done a further couple of two hour washes since and each time the wash water is coming out brown.

Samples of the wash water feel soapy and don't separate into phases.  Anyone had the same or know why the water is brown?

[K.H]

Only guessing but i wonder if your normal procedure removes more glyc?,its the only thing i can think of that could turn wash water brown

[Julian]

I did make the mistake of leaving the heater on for a short while during the final settling period, but it was up to set point temperature and the heater was only pulsing briefly every second or so.  I can't believe that has had such a dramatic effect.  Glycerol was about the normal quantity and Bio looked quite clear when pumped into the settling tank.

I might try drying a sample and do a 3/27 again ... possible reverse reaction?

[K.H]

Ive often heard "reverse reaction" but as yet ive never met anyone who can confirm it

[Julian]

Just heated Bio off the top of the barrel to 85°C, no popping or crackling and went perfectly clear.  3/27 test, although a little too hot at 26°C, was better than the one during processing.

Will try a soap test.  Off to the pub, so I'll do it next I get a chance.

[K.H]

Good decision,pub that is!

[Head Womble]

I'm pretty sure any alcohol prevents formation of emulsions and stops soaps from foaming, which is why jelly batches are recoverable by adding Methanol to return to liquid, then doing glyc/water wash.

Something I noticed a couple of years ago with WBD and water prewash was that it was a lot less forgiving of overdosing the catalyst.  Removing the Methanol made jelly formation much more likely if anything was out.

Very interesting Tony, I have suffered many times, but this was often with a small amount of dropout in the 27/3.

[Tony]

That might imply your emulsions were because of monoglycerides though rather than from too much catalyst?

[Julian]

Did an NB soap test on the sample that I heated and got a result of 30ppm.  I find detecting the colour changes very difficult with this test and suspect that the result should be quite a bit higher than the figure I arrived at.

However, I bit the bullet and drained the water from the bottom of the tank.  During draining, it changed from a bio colour to a light brown and back to a bio colour again.  I took samples of each three colours stages.  The first two have remained the same but the third is showing signs of separation, so I guess I must have drained a little bio water mix.

I've started misting again and the water is running a light milky white.  My guess is that stupidly leaving the heater on dispersed more glycerine into the bio than I first thought ... lesson to be learnt there"!

Anyhow, all that fafing about totally devalues the original exercise, so I'll have to have another bash at some point.

[Carrington]

Has anyone tried doing a base titration on reacted bio. Turin the result you should be able to determin how much acid solution you can mix with the bio before water washing. Doing this allows you to pump wash from the start and removes any chance of creating emulsion.
When I was producing in the garage I would do a 50/50 test with different strengths of acid till I got a clear water pass then work out the amount for the batch, mix in for a few mins then straight into pump wash. By doing a soap test the figure required should be much simpler to work out