Biopowered - vegetable oil and biodiesel forum
Biodiesel => Chemistry and process => Topic started by: neisel on April 14, 2013, 04:14:19 PM
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In the middle of a batch right now & having a problem with glyc not separating after glyc washing.
I had some scruffy, bitty, Chinese take way oil in cubies sitting in the garden & got tired of looking at them today.
Filtered big bits out, dropped about 0.5 litre of water & added about 35 litres of glyc (just because I had it & wanted to use it up) to about 110 litres of oil. I don't think it was bone dry & certainly wasn't as dry as the oil I'd normally take from the top of an IBC, but figured the glyc wash would dry & clean it. Circulated at 70c for over an hour & let settle for 75 mins. Went to drain the glyc & there isn't any, it all appears to be still mixed in with the oil.
Any help telling me I have done wrong & how I fix it gratefully received.
TIA.
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Not many have viewed this Niesel (to date) and with my track record there are some who wont post now....but it might help if we knew just how much oil was the "dodgy chinese" stuff
The addatives that these establishments use can interfere enormously with what we do!
Deffo a starting point for a solution.
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Just under 60 litres was from the Chinese place, the rest from one of the places I usually get it from.
TBH, apart from there being a lot of crispy bits & crap in the Chinese oil it looked ok.
Further reading & advice from someone in the know leads me to believe my feedstock was too wet to glyc wash. Advice so far has been to let it cool overnight until cold, drop the glyc & start again.
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How's it looking now? It can take a while to drop out.
If not, try adding more glyc if you have it.
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In the middle of a batch right now & having a problem with glyc not separating after glyc washing.
I had some scruffy, bitty, Chinese take way oil in cubies sitting in the garden & got tired of looking at them today.
Filtered big bits out, dropped about 0.5 litre of water & added about 35 litres of glyc (just because I had it & wanted to use it up) to about 110 litres of oil. I don't think it was bone dry & certainly wasn't as dry as the oil I'd normally take from the top of an IBC, but figured the glyc wash would dry & clean it. Circulated at 70c for over an hour & let settle for 75 mins. Went to drain the glyc & there isn't any, it all appears to be still mixed in with the oil.
Any help telling me I have done wrong & how I fix it gratefully received.
TIA.
In instances like this I tend to leave for a few days for the glyc to drop, I have always found it does in the end but never the full amount of what went in !
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How's it looking now? It can take a while to drop out.
If not, try adding more glyc if you have it.
It looks the same, no separation.
I have about 20 litres of glyc but can't remember if I've used it once already to glyc wash.
I'm inclined to leave it now until I have some free time later in the week. Hopefully, in about 4 days when I go back to it it will have separated & I can proceed.
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So you've used over 30% of glyc in which to dry and treat this oil which contains around 50% chinese takeaway (CT) oil and there is no drop out.
Steve and Andy suggests that on standing it will drop out. Have you tried using Julians "human centrifuge" to try and force it to drop?
While I have no experience of using CT oil having no dropout of glyc from a 30% wash does seem rather odd.
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I agree that if the oil is too wet you can have separation problems, I've suffered this in the past.
If you have no more gly to add in you could try heating it and condensing off the water.
I've not tried this myself, but in theory I see no reason why it wont work,
try a small sample before committing to the whole batch.
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If you're using NaOH or ASM don't leave it to cool, you may block the pipes and the bottom of the reactor.
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I used to use a lot of Chinese oil which used to glue itself to the heaters and burn them out. I found that if I poured about 25 litres of glyc into 150 litres of oil and let settle I would then drain out about 35 litres of sludge. It would then process as normal.
BUT, I found that I had to let it settle for at least a couple of days.
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I'm using KOH & methanol so no solidification probs.
Just checked it & no change. I'll leave it overnight & hope something miraculous happens.
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Neil
the four days that you mention, should be enough for separation. For future batches you defo want to dewater by heating and leaving to settle overnight. Glyc brings the water ppm's down to a level better than normal dewatering and therefore allow a better reaction, but shouldn't be used as you primary dewatering method.
There are no short cuts, this end of the process.
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Just had a look at it & a lot of glyc is sitting in the bottom of the tank.
I won't have time to finish cooking this batch now so it'll sit for at least another 24 hours.
Thanks for the help!
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Just had a look at it & a lot of glyc is sitting in the bottom of the tank.
I won't have time to finish cooking this batch now so it'll sit for at least another 24 hours.
Thanks for the help!
Great news.
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Just had a look at it & a lot of glyc is sitting in the bottom of the tank.
I won't have time to finish cooking this batch now so it'll sit for at least another 24 hours.
Thanks for the help!
Good news eh.
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To update this.
I had 100% reaction & no unconverted oil after doing the first stage using 17% meths & 8 grms of KOH.
Anybody have any idea why that should be the case?
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To update this.
I had 100% reaction & no unconverted oil after doing the first stage using 17% meths & 8 grms of KOH.
Anybody have any idea why that should be the case?
Low titrating dry oil.
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The initial problem of the glyc not dropping out was diagnosed as wet oil. Are you saying the glyc wash & leaving it for a few days made it dry enough to get away with a one stage treatment?
If that's the case I might do it every time.
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I'm pleased that you got this sorted niesel but as a caviat it should be mentioned that leaving glyc wash for 4 days inside a reactor could result is a mother of a problem if you use NaOH. This is more for newbies reading this than the more experienced brewers.
I have to say I've never experinced a sitution where the glyc fails to drop and I use the glyc wash as my only drying method....but I do know my oil.
As an aside it may also be prudent to take a sample from the reactor before turning off the pump. You can then see what's going on inside the processor from the outside ;)
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Neisel did the glyc drop out on it's own or did you do something?
I haven't done a glycwash for a long time but I had the glyc/wvo mix go really thick and gloopy like marg/butter and had to add more wvo to get it to separate again
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The glyc dropped out on it's own, I did nothing extra except give it time to do whatever it was going to do.
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Neisel did the glyc drop out on it's own or did you do something?
I haven't done a glycwash for a long time but I had the glyc/wvo mix go really thick and gloopy like marg/butter and had to add more wvo to get it to separate again
Was this with the oil you got from me ?