Just before christmas I started a 300lt batch, below is the steps taken.
1. dried & filtered 300lts oil.
2. heated oil to 56 deg C
3. mixed 2.2kgs koh into 46lts methanol.
3. mixed methoxide mix into 300lts of oil
4. mixed for 1 to 2 hours.
5. left over night.
I would normally carry on the process the next day but haven't been able to do so for health reasons.
I went to the batch yesterday to find that it looks like no split had taken place, I heated it up again & mixed it for 30 mins left over night but still the same, no drop out... any ideas on how to recover this please.
What did the oil titrate?
By my calculations you used about 7.3g KOH and 150.3ml methanol per litre of WVO.
If I were to start guessing, I would say that you probably did not use enough KOH, but that is dependent on the titration of the WVO.
Hi Tilly, I don't titrate on my first stage... below is my routine.
1. dry oil & filter
2. Fill main tank to 300Lts.
3. heat to 56 - 59 degrees.
4. Measure out 48 litres of methanol.
5. Weigh 2.5kg (KOH) & add into the 48 litres of methanol & mix.
6. When main tank temperature is at 59 degrees open valve 4 until all the methoxide has been added to the mix.
7. Pump/mix for 1 hour, at 55-60c.
8. Allow the reaction to stand over night, then drain the glycerol.
9. Take 10ml of biodiesel from the top and add to titration flask.
10. Add 90ml methanol into the titration flask at room temperature.
11. Add the stopper and shake, let this stand for the fallout to collect. (30 mins)
12. Measure the unreacted oil in flask. (Refer to Titration chart).
13. Multiply the number of unreacted litres of oil x 7.5 to give you the amount of KOH. to add into the remaining 12 litres of methanol.
I.e. if there is 3ml dropout then you have 30% unreacted oil remaining so this would be 30x7.5=225 grams of KOH into 12Lts methanol.
14. Pump/mix for 60mins.
15. Allow the reaction to stand over nights, then drain the glycerol.
16. Take 10ml of biodiesel from the top and add to titration flask.
17. Add 90ml methanol into the titration flask at room temperature.
18. Add the stopper and shake, let this stand for the fallout to collect.
19. Measure the unreacted oil. (Refer to Titration chart) shouldn’t be any.
wash & then dry.
I suspected that was the case.
Unfortunately titrationless 2 stage Base/Base methods are a nonsense unless the titration of the oil falls within a narrow range.
When you use a procedure that starts out "make a guess at the titration of your oil" sometimes you win and sometimes you lose.
It seems you did not win this time.
At this point you are left to try to guess what to do next.
You might do a titration and find that the titration of the WVO was originally so high that there are still FFA's left in the oil.
That would be the case if the oil you used originally titrated more than about 7 KOH.
If it were me and I was absolutely sure there had not been separation, I would start doing one litre test batches beginning with 2g KOH mixed into 50ml methanol and increasing the KOH a few grams per litre until I achieved separation.
Then I would use that formula for the remainder of the batch.
Thanks very much for your help, I will give this a try in the next day or so...
I only collect from 1 restaurant & have never had a bad batch of oil from them as the head chef is a mate & he keeps the oil inside in the warn & dry, the oil is pre filtered on site through fine mesh baskets.
I am wondering if the amount of time that has passed (nearly 2 months) may have anything to do with it.
Do you know what happens to first stage bio sat on top of glycerol if it sits there for a long period of time?
It would just sit there.
I have some one litre test batches that have been sitting on top of their glycerine for years.
Thanks... good to know.
I will keep you informed on how I get on with the test batches...
Thanks again for your time and help.
The reason I started doing it this way is I was getting mixed results when titrating & found it to be unreliable... I friend put me onto this way of doing it & it has worked for me up until now...
would you have any help for titrating?
When I titrate I use the World Famous Chopstick titration Technique (Pat Pend)
The thing you need to keep in mind is that if you do a 2 stage Base/ Base procedure you need to have ALL the KOH necessary to neutralize all the FFA's plus an additional amount to perform some of the transesterfication for the first stage.
That means that if you use 5.3g KOH in the first stage you will not achieve separation with oil titrating much above 4.This message has been edited. Last edited by: Tilly,
Just got around to doing to testing... I got it to split using 4grams & 50ml of methanol.
What would be the amount of koh & methanol needed to finish it off or would there be more testing?
Many thanks for your help.
Good to hear you have succeeded in getting separation.
From here I would first check to see if it passes the 3/27 test.
If it does not pass, after reacting the rest of the batch I would then start at step 9 in your earlier post describing how you normally process and you should be able to finish off the batch satisfactorily.This message has been edited. Last edited by: Tilly,
sorry for the delay, been working away again... just thought i'd bring you up to date... all is fine the batch has now been fully reacted & used
Thanks very much again for your help.
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