Very poor conversion on latest batch

[neisel]

Recently I was given 700L of oil by someone giving up on BD. It's been sitting a long time in cubies & had separated about 50/50 with clear clean liquid at the top & whites at the bottom, which I think would be solid in colder weather. It hadn't been filtered. The oil I normally use is MUCH better, changed once week, clear, little debris, no water, no whites.

I decided to make a batch using the worst of the whites, thinking it would make fuel good to be used in the summer.

Usual method employed - 145L of raw feedstock dumped into processor & left for 24 hours, drained about 3ishL of water, then heated to 70, circulated, left sat for 75 mins then drained 1½L more of water, glyc washed 2x for at least 45 mins with 90mins  sitting between washes, once used glyc for 1st wash & virgin for the 2nd. Clear delineation of glys & oil on both washes, as much came out as went in. I'm pretty sure the oil was dry.

1st stage: I have settled on a method where I underdose stage 1, using 15L of methanol & 500grms of NaOH, which gives me a conversion of 70-80%.

2nd stage fine tuned depending on figures from 1st stage conversion. Always get 100 or 99.5% conversion & fuel looks & works great.

This time after the 1st stage (done at 60C) I reckon I got a 25% conversion with the usual 15L/500grms & it looks funny, almost like there are tiny globules of fat/lard in it. Glyc produced was about half what I would expect to see.

Is it possible my usual underdosing technique wasn't powerful enough to push the reaction on this shitty oil through? I think it unlikely but am I mistaken on the dryness & the oil was still wet?

Any ideas on what has gone wrong or what I can do to finish this batch?

TIA.

[neisel]

Should have said, the methanol & NaOH were from batches I've used before without issue.

[dgs]

IMO 90 mins is nowhere near long enough to get rid of enough glyc to the point where it won't be a problem for S1. If your whites were quite wet, which is very likely, then the glyc will be wet too. If some of this glyc is present during S1 then it can effect the process. Also remember residual glycerol tries to eat up your chemicals.

I've always found the methanol starvation method a little counter-productive. I've never really got anywhere with S1 unless I use around 14%

[neisel]

dgs,

IIRC correctly you process at ambient temps while I've given up on ambient glyc washes 'cos it takes forever (days) for the glyc to drop & separate. My glyc wash was at something between 60-70C & the drop out rate is MUCH, MUCH faster than at ambient temps.

That said, all I can think of as a cause for this troublesome batch is wet oil. Going wth that theary should I not use any glyc produced from this batch as a treatment for my next one?

I've never titrated oil & know nothing of titration. Is it possible this stuff was so off the scale that it needed more chemicals?

[dgs]

dgs,

IIRC correctly you process at ambient temps while I've given up on ambient glyc washes 'cos it takes forever (days) for the glyc to drop & separate. My glyc wash was at something between 60-70C & the drop out rate is MUCH, MUCH faster than at ambient temps.

That said, all I can think of as a cause for this troublesome batch is wet oil. Going wth that theary should I not use any glyc produced from this batch as a treatment for my next one?

I've never titrated oil & know nothing of titration. Is it possible this stuff was so off the scale that it needed more chemicals?

From tests I have done,  glyc with 10% water added still dries oil to low levels so your glyc should be ok to use.

It is possible that the titration was very high which would explain the low conversion.

Many years ago I resigned myself to never process any oil that showed any titration, so my process went easier. I pre glyc wash at ambient temp in an outside IBC using 100 litre batches of glyc with 7 to 800 litres of oil. This means my oil never titrates and usually shows around 15 to 20% conversion before processing.

For most people this is impractical but maybe glyc washing the next batch in advance might be the way foreward.

You know you can check the alkalinity of the oil after glyc washing with something like litmus paper. If it shows alkalinity then there are no ffa's left and it's good to process. You can always add a little methoxide to your 2nd glyc wash which gives you a good start. As you glyc wash twice you will recover any chems you add.

[Chug]

Seems like your glyc wash should have sorted wet oil so it's probably highly used oil, a lot of the crap whites I collected in the past were usually high titrating, unless I'm desperate I swerve all the crap from other people settling and taking the good stuff.

[kamaangir]

I am not sure if this anecdote is related to your particular predicament but I once also tried to brew a batch using mostly solid oil.
I had a 60l metal drum that had a 3kw element in it that was plumbed into my processor, I put enough Liquid oil to cover the element (which had the thermostat bypassed due to previous misadventures!) then dumped in tub after tub of solids. Once the dewatering drum was full I let it get to a rolling boil and boy howdy (as the yanks say) was there water in the solids, there was a massive vapour/steam cloud above the drum and once it had cleared I had lost 20-30% volume!! I let it get to smoke point before dumping more tubs in. 130l took me most of the day to dewater.

My impression is that solids hold a huge amount of water in suspension compared to liquid veg, this stuff had not settled to the bottom of the tubs, which I drained.

Like I say just my experience of dealing with solids.

[neisel]

I think the problem with this batch was insufficient de-watering. I'll do it at hotter temps for longer for my next batch.

[neisel]

Same batch, different problem.

After a clean 100% pass on the 10/90 test I've had problems drying this stuff to the usual crystal clear pass & have now given up after about 6 hours at high temps I never normally use, and this after it had sat for 3 full days in 30-35C heat. No matter what I do I cannot get rid of the little bit of cloudiness that occurs after 2-3 hours in the fridge. I will use it as is.

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[Chug]

Given the processing problems it could be that your oil was high titrating and had more saturated fats in it and the resulting hazy bio is just these starting to gel as the temp drops?

[neisel]

It's crystal clear at room temps & only goes a bit hazy after several hours in the fridge. Doing multiple tests I tried to hurry things along on the cooling front by putting the tests in the freezer. I left it too long one time & a white semi solid deposit started forming on the bottom. Dunno if this is what BD normally looks like when it starts to freeze or if the deposit is indicative of high sat fats. Left in the hot sun for about 10 mins & this raised the temp enough for this stuff to dissolve.

I reckon it's OK to use in the summer.

[neisel]

Well, second batch of shitty whites underway & it's looking even worse than the first one!

For the 2nd batch I dumped the WVO in the processor a couple of days ago & let any water drop to the bottom, then drained it. Got about a pint. I de-watered at 90 degrees for several hours, circulated to make sure all of the oil was exposed to the same temp, & was surprised to see virtually no water drop out. I glyc washed it THREE TIMES  at between 60-70, leaving the last lot of glyc to drop out for >14 hours overnight. This a.m. I drained that glyc (clear delineation between glyc & oil, same amount out as went in) & introduced the usual 15L of reclaimed methanol & 500grms of NaOH. Now, after processing for 75-80 mins there is zero glyc showing in the processor & the 10/90 shows a v. disappointing 35% conversion. 10/90 flask has the same fatty globules as first batch & again looks different from batch made from good oil.

https://postimg.cc/QBWvBXKH

Don't know WTF to do now, there's nothing in the processor to drop out & no room in the processor to add anymore chems.

Any suggestions?

TIA.

[neisel]

While waiting for guidance from the panel here I figured the only way to proceed was indeed to proceed, so using the http://biopowered.co.uk/forum/tools/notitration.php I went to stage 2. 11L & 480grms of NaOH was required so I dropped out approx 11L from my processor & went ahead with stage 2. I now appear to have a 100% clear 10/90 pass & all the glyc from Stage 1 & 2 in the machine. There is a lot of glyc, which I think I will leave to settle (& hopefully diminish a bit) overnight. BD yield will be down a few litres & methanol average up, but it couldn't have been much easier to fix & could have been much worse.

In the past I've heard people talk of reactions stalling & needing to be pushed over the line, is that what happened here? If yes, would using more chemicals in the first stage avoid this problem in the future?

[dgs]

You are using only just over 10% methanol and 3.5 gms/litre NaOH for S1, which I would say is so little it must be counter-productive. I've never found that less methanol than about 13% is helpful on S1.

You mention reactions stalling, remember that producing more glycerol won't help as it holds up the conversion with its affinity for methanol. you've got 2 stages worth of glycerol in there which is even worse for holding back S2.

[neisel]

dgs,

When using 'good' runny oil the same amount of chemicals result in a conversion rate of about 75-80%. Using 20 litres & 700grms on the first stage raises this to about the low 90s % wise. Over time I've found it more efficient to underdose on the first stage, knowing about 20-25% will be unconverted, & then dial it in on the second. With good oil I can usually get 100% conversion of 145L using 21L & around 700grms. I've been making batches of v. good BD using these ratios & the same method for years without issue.

I think it's the oil that's the problem here, not the amount of the chemicals.