Returning to bio after a long break

[Steveng]

Hello all, and thanks for all the information I've already gleaned by reading threads over the last week or so.

I ran a couple of fords for 4 years approx on nothing but homemade biodiesel made in a processor that I designed and built myself. Recently due to a stroke of luck, I cleaned up and disposed of a biodiesel production business, which has left me with 2500L of oil/fat and some very nice processing machinery.

I'm using my old 80L home made unit to get back into production before getting the big rig running. Needless to say I'm hitting problems.

I did a single stage using Koh which, although it cleaned the oil up, was not well converted. The second attempt was 2 stage, using 8% methanol + 1g H2SO4 per L; then 12% methanol + 3.3g Koh per L. The "foolproof" method from JTF.

Only it wasn't so it seems; my temperatures and time periods are not at fault. My chemicals are old but maybe suspect so will need to check them. The oil/fat was dewatered thoroughly and sealed in cans, but it looks very dark, and has stood for 8 years. I tried adding 400g Koh directly and cooking again for a couple of hours. Another 400g and no marked improvement, although it did start to settle out after a couple of days. No pass on 3-27 test. Then I added 5L methanol with 500g Koh and cooked it for 4+ hours, hoping to push it over the line.

The result was about 40% conversion which passed the dropout test. I took a 10ml sample of the glycerol? and shook it with 10ml of water to release the soap, then put in 2ml of vinegar. Something grotty has risen to the top and am waiting to see if there's enough oil to be worth salvaging.

I've read that oil that's been stood has FFA problems when exposed to the UV. Two ibcs full are waiting, lol.

Anyone got any ideas on what to do? I did sell 10 tonnes of the same stock to a reputable recycler whose analysis was 6.5 and they were happy to pay for it. Could it be that it's had it and not usable in reality?

Thanks in advance for any suggestions, and please excuse my ignorance as I'm no chemist and very rusty.

[dgs]

Hi Steveng and welcome back.

Very confused by your post, you have done a sort of acid esterification on your oil and yet I can't see anything about titration. In any case being directed by anything on jtf probably isn't a good idea.

  Try a glycerol pre treatment on some of this oil. It will reduce your titration and make sure your oil has no excess water in it.

Also try to titrate your oil, at least you would know where you are but leave the 'foolproof' method alone. Even if it titrates really high you are best to use the 2 stage no titration method.

Refer to the wiki on here for better help, forget jtf.

https://biopowered.co.uk/wiki/Glycerol_wash

[dgs]

The old oil that I tangled with a couple of years ago had been stood in IBC's for at least 6 to 7 years. Although it titrated high (about 8 KOH from memory) it was quite light coloured.

Strange thing was it showed no dropoput on a 10/90 test (as if fully converted) I spoke to a friend, a commercial bio producer/chemist who had come across this before. Apparantly the u/v had, over the years, broken down the fatty acid chains so that the 'oil' was soluble in methanol.

Steve, you could try a 10/90 test (3/27 if you must) on your oil and just see if you get the full sample size dropping out.

[Tony]

Welcome back to the bio world.

Have you got or can you get an alcohol hydrometer?  One that will read up to 100%?

It's critically important to know whether your Methanol is fit for purpose (100%) or polluted with something else, otherwise you'll struggle no matter how good your method.
I got some reclaimed methanol and KOH from a biodiesel  place that was shutting down and it was hard work getting a clear pass, even with three stages of conversion and many years of experience!  The pleasure of going back to virgin meth and good KOH was like night and day.

[countrypaul]

I did a single stage using Koh which, although it cleaned the oil up, was not well converted. The second attempt was 2 stage, using 8% methanol + 1g H2SO4 per L; then 12% methanol + 3.3g Koh per L. The "foolproof" method from JTF.

If the oil you have titrated at 6.5 (like the oil you sold) then you would need 6.5g/L of NaOH just to neutralise the FFA (assuming the acid value was measured with NaOH) normally that would be 9.1 g/L of KOH (more likely 10g if the KOH is only 90%).  You do not say how much you used for the first stage, but if less than that you would get very poor if any conversion to bio. To make matters worse, the treatment with sulphuric acid would convert any soap produced and left in the oil back to FFA. 1g H2SO4 woud reverse approximately what 2g of KOH had converted to soap. If teh first stage was with 7g/L or less of KOH then the second stage with 3.3g/L KOH would therefore probabyl result in a similar situation to the first stage due to there still being alot of FFA present.

I totally agree with Dave, best to ignore JTF.

Generally speaking the base level for conversion used by most on here is 5g/L of NaOH (or 7g/l KOH) plus the titration.

Given your present situation, I would suggest trying some Dr Pepper test, using 1L of oil for each and several sets of reagents: say 10g KOH + 200ml MeOH and  15g KOH + 200ml MeOH, then if the 15 is incomplete try 20g KOH + 200ml MeOH.  Try a 10/90 test on each test and if the conversion is only partial, drop the glycerol and reprocess as a 2 stage. You should be able to work out the minimum amount of reagents you can get away with.

If you then try a full 80L batch remember to use the glycerol to clean up the oil for you next batch first, then tr Dr Pepper on the cleaned up oil as it should require much less reagent than the first batch.

[dgs]

I did a single stage using Koh which, although it cleaned the oil up, was not well converted. The second attempt was 2 stage, using 8% methanol + 1g H2SO4 per L; then 12% methanol + 3.3g Koh per L. The "foolproof" method from JTF.

If the oil you have titrated at 6.5 (like the oil you sold) then you would need 6.5g/L of NaOH just to neutralise the FFA (assuming the acid value was measured with NaOH) normally that would be 9.1 g/L of KOH (more likely 10g if the KOH is only 90%).  You do not say how much you used for the first stage, but if less than that you would get very poor if any conversion to bio. To make matters worse, the treatment with sulphuric acid would convert any soap produced and left in the oil back to FFA. 1g H2SO4 woud reverse approximately what 2g of KOH had converted to soap. If teh first stage was with 7g/L or less of KOH then the second stage with 3.3g/L KOH would therefore probabyl result in a similar situation to the first stage due to there still being alot of FFA present.

I totally agree with Dave, best to ignore JTF.

Generally speaking the base level for conversion used by most on here is 5g/L of NaOH (or 7g/l KOH) plus the titration.

Given your present situation, I would suggest trying some Dr Pepper test, using 1L of oil for each and several sets of reagents: say 10g KOH + 200ml MeOH and  15g KOH + 200ml MeOH, then if the 15 is incomplete try 20g KOH + 200ml MeOH.  Try a 10/90 test on each test and if the conversion is only partial, drop the glycerol and reprocess as a 2 stage. You should be able to work out the minimum amount of reagents you can get away with.

If you then try a full 80L batch remember to use the glycerol to clean up the oil for you next batch first, then tr Dr Pepper on the cleaned up oil as it should require much less reagent than the first batch.

Hi Paul, i think Steves addition of sulphuric was before any normal conversion ie he was doing the acid esterification method where heat and mixing with the oil, methanol and sulphuric gradually reduce the titration of the oil (over hours) to an acceptable level to perform a more conventional transesterification method.

The method needs constant monitoring with many titrations over several hours and needs an initial accurate titration to calculate the initial amount of sulphuric. I didn't see any of those details in Steves description.

[Steveng]

Wow, thanks for the advice and suggestions.

The first lot I processed on single stage was  titrated prior to starting and the second lot was titrated after the 2nd stage when in theory it should have been converted, according to the method used.

I will avoid jtf in future as the consensus indicates quality issues with info.
I do have several alcohol hydrometers kicking around so the methanol will be tested; I did have some bad stuff years ago and it was a wasteful exasperating nuisance. Like you say, night and day with nice new 99.9%

Glycerol washing is something I was looking at before stopping 7 years ago. There's plenty here to try it. I am only too aware of drying after the occasional batch failure due to impatience, lesson learned, lol.

When I say 3/27 I do 9/1 as I'm not in the USA and as we know, things are smaller here for reasons of economy.

The reason for the acid pre treatment was due to previous success when converting palm oil and carvery sludge. The "oil" I have now is kebab/chickenfat/oil, which is between solid and light liquid through the phases. I had to put a heat gun on the pipework for an hour to unblock it after initial filling. (Must replace the second heating element)

At this stage going to try dr pepper 1 litre batches and buy some proper titration reagents, the turmeric may be stale after 14 years. Dropout tests too before starting if sufficiently liquid.

Incidentally, the sludge, water, vinegar experiment has revealed an appreciable amount of oil left. If unconverted presumably a titration etc, add more log and cook again?

[dgs]

Please, please please  ditch the 1/9 test and buy yourself a proper 10/90 tube. you owe it to yourself to make your testing as accurate as possible. How can you really tell whats happening using a 1ml sample.

Examine the Wiki and go onto 2 stage no titration after glyc washing. You will never do titrations again.

[Steveng]

Thanks dgs, I've never heard of a 10/90 tube. Like you said I'll go to wiki and get up to date with methods, my early days were converting really nice hardly used oil which progressed to more difficult stock. Now I'm facing more challenging stock without the practice etc.

[countrypaul]

I did a single stage using Koh which, although it cleaned the oil up, was not well converted. The second attempt was 2 stage, using 8% methanol + 1g H2SO4 per L; then 12% methanol + 3.3g Koh per L. The "foolproof" method from JTF.

If the oil you have titrated at 6.5 (like the oil you sold) then you would need 6.5g/L of NaOH just to neutralise the FFA (assuming the acid value was measured with NaOH) normally that would be 9.1 g/L of KOH (more likely 10g if the KOH is only 90%).  You do not say how much you used for the first stage, but if less than that you would get very poor if any conversion to bio. To make matters worse, the treatment with sulphuric acid would convert any soap produced and left in the oil back to FFA. 1g H2SO4 woud reverse approximately what 2g of KOH had converted to soap. If teh first stage was with 7g/L or less of KOH then the second stage with 3.3g/L KOH would therefore probabyl result in a similar situation to the first stage due to there still being alot of FFA present.

I totally agree with Dave, best to ignore JTF.

Generally speaking the base level for conversion used by most on here is 5g/L of NaOH (or 7g/l KOH) plus the titration.

Given your present situation, I would suggest trying some Dr Pepper test, using 1L of oil for each and several sets of reagents: say 10g KOH + 200ml MeOH and  15g KOH + 200ml MeOH, then if the 15 is incomplete try 20g KOH + 200ml MeOH.  Try a 10/90 test on each test and if the conversion is only partial, drop the glycerol and reprocess as a 2 stage. You should be able to work out the minimum amount of reagents you can get away with.

If you then try a full 80L batch remember to use the glycerol to clean up the oil for you next batch first, then tr Dr Pepper on the cleaned up oil as it should require much less reagent than the first batch.

Hi Paul, i think Steves addition of sulphuric was before any normal conversion ie he was doing the acid esterification method where heat and mixing with the oil, methanol and sulphuric gradually reduce the titration of the oil (over hours) to an acceptable level to perform a more conventional transesterification method.

The method needs constant monitoring with many titrations over several hours and needs an initial accurate titration to calculate the initial amount of sulphuric. I didn't see any of those details in Steves description.

Hi Dave, re-reading things I think you may be right regarding the acid esterification. When I read it earlier I took it to mean second attempt on the same batch.

Steve, some on here use a 25/225 test rather than a 3/27 or 10/90, ultimately properly converted bio should give a clear result at any ratio, so I often add more bio upto 12/27. Any dropout shows an incomplete process - and remember the reagents should be at 20C.