To wash or not to wash

[CanidrivE]

Hi all,  This happen last year, so only now getting round to ask about it now, read on.

Made me last batch of the year "Dec" 200ltr.  When I done from both top and bottom of the reactor the 10/90 test with warm and cold methanol, I got 4 good clear passes, "as usual".
Rather than turn on pump, add 20ltr of water, run then stop and drain pipes and then start mist washing, I skipped the run part and went right into mist washing, after 30 minutes I opened the over flow pipe and finally seen the wash water starting to run from the over flow pipe.  This was left to run for the next 4 - 6 hours until the edge of dark, turned off water, walked into garage, no lights on, closed over flow pipe, job done..( wash water stayed very white all day. ? )

Next day walked out to back yard, turned on tap for a second quick wash, walked into garage to open over flow pipe, """ what a (insert many effing words here) mess the tray the reactor sits in was full of oil, so was part of the floor going out under the garage door and part of the drive way.. spent most of that day cleaning

Following day,  back to oil / diesel,,, I drained off the wash water which was like watered down milk in color, looked in at diesel or should I call it B100, it just looked like un-dryed fuel.
So, I put in a bit of acid, added my usual 20ltr of water and ran the pump for 15 - 30 minutes, shut down drained pipe and mist washed and every thing looked normal.

I lost 50ltr's of good B100 or 25% of my usual yield.

I am lost as to what may have went wrong,  also to those that don't wash bio, would that been one of the reason's why?

Dave

[BANDIT2]

It's in your mop bucket isn't it

[dgs]

There is no need to take samples from top and bottom, bio and oil are miscible in all proportions. Why would you use warm methanol for your 10/90. Even though Jan Warnqvist did his original tests at 20degs it isn't really cold enough. 10 to 15degs is a more accurate temperature. Don't read the dropout until the methanol phase is completely clear.

The test isn't really accurate to use if you water wash. By that I mean if the test is clear (but just clear) you will be left with monoglycerides in the mix which will/can cock up your water wash no end. The trick is to add a little more catalyst/meth as a tiny last reaction even if your 10/90 is clear. This will convert the mono's.

I like to get a dropout of 0.2 to 0.5mls on the penultimate reaction, so I add the correct amount of KOH for the dropout plus 30gms per 100litres of bio. This way you can fine tune the reaction end point. If you then use the prewash method  (water plus glycerol) you should find it leaves the soap at <100ppm or thereabouts. You can then pump/compressor wash as hard as you want and there is no way you will get an emulsion due to soap or mono's.

You are correct as this is one of the reasons more people don't water wash, its all to do with fine tuning the reaction end point.

One last thing, Please don't use acid, if you have soap you will put an amount of ffa's back into the bio.

[nigelb]

Your biggest mistake was missing out the post reaction wash (prewash). This takes out loads of soap and makes water washing so much easier. Experiments conducted by myself many years ago gave startling results.
Raw unwashed bio...13000ppm of soap
Prewashed bio...1300ppm of soap.

My advice is dont miss out this important step.

[dgs]

Your biggest mistake was missing out the post reaction wash (prewash). This takes out loads of soap and makes water washing so much easier. Experiments conducted by myself many years ago gave startling results.
Raw unwashed bio...13000ppm of soap
Prewashed bio...1300ppm of soap.

My advice is dont miss out this important step.

Quite correct Nige, my results are Ex process raw bio, anything upwards of 3000ppm, after prewash (only 4 litres of glyc and 3 litres of water in 200 litre batch) actually in spec at <66ppm.

[dgs]

Just a little afterthought here. When most of the wet glycerol has settled I use the bubbler with the bubble head about 10" from the cone bottom. This seems to encourage the last of the wet glycerol to settle out, leaving the bio very low in soap, as mentioned above my titration is very often 0.2mls or slightly less eq to 64ppm or less. This is before the 1st wash which is why i can use a very aggressive wash technique from the start.
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« Last Edit: Today at 09:45:09 PM by dgs »

[CanidrivE]

Hi guys, thanks for the reply's, due to the fact I could not be arsed to turn on the computer, hence the slow reply.

The reason behind the many 90/10 test was I remembered some one on a form saying about the temp affecting the out come, "dgs, it may have been you" methanol from the house 20 - 25deg C, and the garage maybe as low as 5 deg C. I just wanted to see for myself was there a difference, all 4 little 100ml flasks lined up had the same colour of B100, I should have taken a photograph of them..   

nigelb, I did do the prewash, being doing that way for years and yes you are correct, it does bring the soaps way down and it help the look and finish of the end result, when I use to test it, I ALWAYS got between 12 - 23ppm and first few times I done the test I thought I was doing the test wrong, so I got help, and still got the same result.

dgs, returning to your first post on here, you said "The trick is to add a little more catalyst/meth" that is sort of what I do, only I have ONLY NaOH "no KOH"  only this / that last time round I did not use the pump wash, just mist wash, it was only after the cock up that I put a drop of acid into the mix to get the soap to slip out and lie between the water and oil

Water, how much do you add into your prewash Nigel and Dave, I empty or drop out glyce and bio up to the point of 20ltrs this is over a period of days dropping the last bit out.

Dave

Still do not know why the dam thing over flowed and no mob bucket was used in the clean-up, won't say any thing about bandit2 having a large mob 

[nigelb]

I leave in the glyc from stage 2 and add in 8lts-10lts of water for the prewash. Following a couple of hours of settling, drain the glyc/water/soap tansfer the raw bio to the wash tank. 4-5 washes of 10lts at a time. Thats normally enough to reach the eureka moment of clear fuel. Hope that helps.

[dgs]

I leave in the glyc from stage 2 and add in 8lts-10lts of water for the prewash. Following a couple of hours of settling, drain the glyc/water/soap tansfer the raw bio to the wash tank. 4-5 washes of 10lts at a time. Thats normally enough to reach the eureka moment of clear fuel. Hope that helps.

Very similar, I think we are after a rough 50/50 ratio of glyc/water. As my last stage can be tiny I assume at ambient ish temperature processing there is 4 litres of glyc left suspended in the batch. I add 3 litres of water  and usually end up with around 7 litres of wet glyc.