Biopowered - vegetable oil and biodiesel forum
Biodiesel => Chemistry and process => Topic started by: Tony on May 20, 2014, 10:45:57 AM
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I found this one quite interesting...
I did a 125l batch at the weekend. Made methoxide with 17l methanol + 1.1kg NaOH (more than required - excess catalyst - 8.8g/l).
I also had 2l recovered methanol to use from the last batch.
Stage 1
Put in all but 4l of the methoxide + 2l of recovered methanol.
Totals: 15l methanol or 12% by volume, and 840g of NaOH (6.7g/l)
Mixed and drained glyc.
Stage 2
Put in remaining 4l of the methoxide mix.
Mixed, got clear pass, and drained glyc (there wasn't much, just a few litres).
Finishing
Demethed remaining bio phase, recovered 1l before it was up at 95C (didn't take very long, not much meth present in the final mix).
Conclusions
Total methanol consumed by the reaction process was 14.4%, and much less energy spent recovering methanol than normal.
It does suggest that in stage 1 when the glycerol is drained there is very little methanol in it. Perhaps because 12% is below the average stoichiometric ratio for oil and plenty of catalyst is present, almost all methanol is consumed by the reaction?
Then stage 2 there is excess methanol, but because there isn't much glycerol dropped not much unconsumed methanol is lost with it, leaving most in the biodiesel phase for recovery.
I've not done WBD for the last few batches (not much point as very little methanol left in the glycerol), instead tinkering with the ratios for the two stages when excess catalyst is present. This one has been the best so far in terms of using minimum methanol to get a clear pass.
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I have also wondered if there isnt a safeguard, with regard to soaps, in the 2 stage process, when minimal methanol is used -
Ie. if there are soaps produced in S1, do they stay with the methylester / tryglyceride mix (in to which they are insoluable) or are they removed with the glycerol?
We all know that its the methanol that keeps the soaps in solution with the methylester, so is the prior concept of excess methanol at all times really such a good plan?
Ive been impressed with using 10% methanol (to triglyceride ratio) on both stages. I use 5g / ltr on stage one, but maybe i should try 6g /ltr and see what becomes of it?
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ps.
A few days ago, someone told my (by pm) that with the 10% they found that active demething was not even required - that bubbling for 24hrs seemed to do the trick alone.
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Did you put back first stage glyc and do a wash after the clear pass?
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No I don't wash, settle only.
WATER ;)
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14.4%! as much as that, I'd be a little peeved at that amount.
I regularly get a total consumption of 12.5 - 13%, must be your crappy ol'oil.
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ps.
A few days ago, someone told my (by pm) that with the 10% they found that active demething was not even required - that bubbling for 24hrs seemed to do the trick alone.
I've done this twice now. Let me elaborate on my last brew:
160L of whites were given an insubstantial (just 20L) glyc wash.
S1 used 16L That's 10% meth and 4.5 g/l naoh = an unsurprising 60% conversion.
My meth comes in 20L containers, so S2 = 4L. That works out as 6.25% meth, which should not work. OK, it was a cloudy pass.
No demeth. The bio was bubbled off for 24 hrs as usual. The next evening, I redid the 10/90 - same result. I noticed the S2 glyc. was as solid as WBD glyc and way more fudge-coloured.
There you have it, 20 L meth for 160L batch size, 12.5%.
Someone else verify, please!
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14.4%! as much as that, I'd be a little peeved at that amount.
I regularly get a total consumption of 12.5 - 13%, must be your crappy ol'oil.
It's some right slimy shite at the moment.
12.5-13% I might be about to achieve with WBD and nice oil, but the energy cost of recovering the last bits of meth I suspect would approach the cost of the meth itself (not to mention risking reverse reaction).
With WBD I would typically hit 16% so this is definitely an improvement on process for me.
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ps.
A few days ago, someone told my (by pm) that with the 10% they found that active demething was not even required - that bubbling for 24hrs seemed to do the trick alone.
I've done this twice now. Let me elaborate on my last brew:
160L of whites were given an insubstantial (just 20L) glyc wash.
S1 used 16L That's 10% meth and 4.5 g/l naoh = an unsurprising 60% conversion.
My meth comes in 20L containers, so S2 = 4L. That works out as 6.25% meth, which should not work. OK, it was a cloudy pass.
No demeth. The bio was bubbled off for 24 hrs as usual. The next evening, I redid the 10/90 - same result. I noticed the S2 glyc. was as solid as WBD glyc and way more fudge-coloured.
There you have it, 20 L meth for 160L batch size, 12.5%.
Someone else verify, please!
Did you keep your cloudy pass to see if it got drop out?
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14.4%! as much as that, I'd be a little peeved at that amount.
I regularly get a total consumption of 12.5 - 13%, must be your crappy ol'oil.
It's some right slimy shite at the moment.
12.5-13% I might be about to achieve with WBD and nice oil, but the energy cost of recovering the last bits of meth I suspect would approach the cost of the meth itself (not to mention risking reverse reaction).
With WBD I would typically hit 16% so this is definitely an improvement on process for me.
I haven't WBD'd for years bio only for me.
I use a gross volume of 16 -17% and after demething between 3.5 & 4.5% in approx 80mins at 85c I end up with a nett 12.5%, mind you I am using ASM so no generated water in the methoxide.
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I haven't WBD'd for years bio only for me.
I use a gross volume of 16 -17% and after demething between 3.5 & 4.5% in approx 80mins at 85c I end up with a nett 12.5%, mind you I am using ASM so no generated water in the methoxide.
I'm not sure water generated by the methoxide mix would account for the extra methanol consumption. But I understand that different oil types have different stoichiometric ratios and that may account for it - rapeseed at 11.3% through to 16.3% for coconut oil. I've no idea what I've currently got but it's quite nasty. I think one place in particular I'm going to stop collecting from.
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I'm brewing 95% rape 5% palm, I'm guesstimating the palm content as I settle and syphon off the best liquid but it almost certainly holds palm, plus a small pickup at the interface..
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ps.
A few days ago, someone told my (by pm) that with the 10% they found that active demething was not even required - that bubbling for 24hrs seemed to do the trick alone.
I've done this twice now. Let me elaborate on my last brew:
160L of whites were given an insubstantial (just 20L) glyc wash.
S1 used 16L That's 10% meth and 4.5 g/l naoh = an unsurprising 60% conversion.
My meth comes in 20L containers, so S2 = 4L. That works out as 6.25% meth, which should not work. OK, it was a cloudy pass.
No demeth. The bio was bubbled off for 24 hrs as usual. The next evening, I redid the 10/90 - same result. I noticed the S2 glyc. was as solid as WBD glyc and way more fudge-coloured.
There you have it, 20 L meth for 160L batch size, 12.5%.
Someone else verify, please!
Did you keep your cloudy pass to see if it got drop out?
Aye, I did. (It was actually my usual 'end of process' syringe 1/9).
I was fully expecting to see drop out, proportional to the S2 under-dose of meth, appear the next day.
After 5 days nothing extra had dropped.
Something new I didn't mention. My plant now runs a 70 lpm pump with the 2 stage educator, so on a batch this size there's vigorous mixing going on.
Anyone else like to try a serious under-dose on their next S2? If it fails badly, all you need do is add more meth and mix
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My latest project. I like to delegate, as appropriate :)
(http://i912.photobucket.com/albums/ac327/a111r/DSCN5036_zps3b8fa682.jpg)
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How cute is that! ;D
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I will give it a go on 160L next time I brew, probably next week. I use ASM on the s2 use 2 tam105 and 2 eductors so it is very similar.
BTW I also have a new bio helper for the future, mine goes home for the night though.
(http://i1279.photobucket.com/albums/y521/dickjotec/8aca2c8a0e703d08b57bff4274386c33_zps10497885.jpg)
My grandson and a spare cat!
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My latest project. I like to delegate, as appropriate :)
(http://i912.photobucket.com/albums/ac327/a111r/DSCN5036_zps3b8fa682.jpg)
Oh deer, these cute little buggers suck money out of your wallet faster than their mothers at the hair dressers. :) mother says NO but I can't.
Teach them all you know then in five years time they will be telling you how to do it properly. :)
Congratulations.
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Congrats - I'm looking forward to grandchildren, particularly getting all the fun bits then handing them back when they need changing or are getting grotty ;)
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So, I've been having a problem with having to do too many water washes due to making soaps in my process. I've been using the no tit calculator but still must be dosing too richly - http://www.biopowered.co.uk/forum/tools/notitration.php
Tomorrow I'm going to start a new batch - 140 litres of lovely clear golden oil which will be heated to about 65 degrees & then glyc washed.
What % & litre amounts of methanol & how many grams per litre of KOH should I use for Stage 1 & Stage 2 to achieve 100% conversion with very little soaps so I can wash it no more than 3 or 4 times & be done with it?
TIA.
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My understanding is that soap has two sources, one from the neutralisation of free fatty acids with catalyst (so you get more soap the higher it titrates).
The other is from water present with the oil and catalyst.
There is some water inherent in methoxide made from methanol and potassium/sodium. There is some water created when free fatty acids are neutralised. And of course any water that was in the oil to start with.
How are you drying your oil?
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The oil is from 3 different places, 2 expensive gastro pubs, 1 which changes it every week & 1 twice week & from a good Thai restaurant where it's changed weekly. It's so good I swear I could sell the stuff that's changed twice week to
CTAs businesses less discriminating about their oil where it would be re-used for many more weeks.
It's strained through a kitchen sieve into a full IBC where it sits for at least a month & is pumped from the top, then glyc washed as the first stage of the process.
I do not believe the oil is wet. I used to heat it up, circulate it & let it sit for an hour or 2 before glyc washing but stopped bothering with that after getting about a tablespoon of water (at most) from 140 litres.
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Are we baffled or what?
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That sounds like very good oil (Gastro, like most of mine).
Watery methanol would be my first check.
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The methanol is new (not reclaimed) from a reputable supplier & decanted from a sealed barrel. I don't have any way of testing it but I think it's OK.
Assuming the oil is dry, the methanol is good, the KOH is pure can is it possible that I've been overdosing & creating soaps?
If that could be the case could someone please recommend dosages, %s, volumes I can use on a 2 stage conversion that will minimise or largely eliminate soaps?
140 litres of glyc washed feedstock is the starting point.
TIA.
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do a titrated test, it will give you an idea how acidic it is. that will give you a guide how much to use on 1st stage to achieve around the 90% pass
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do a titrated test, it will give you an idea how acidic it is. that will give you a guide how much to use on 1st stage to achieve around the 90% pass
I don't have any of the stuff to do this, never done it.
Assuming the oil is dry, the methanol is good, the KOH is pure & that the Ph is neutral is it possible that I've been overdosing & creating soaps?
If that could be the case could someone please recommend dosages, %s, volumes I can use on a 2 stage conversion that will minimise or largely eliminate soaps?
140 litres of glyc washed feedstock is the starting point.
TIA.
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Could your problems be to do with bio migration from the glycerol wash?
That happened to me once - i overdosed due to there being less veg than i thought (some of the total volume was recovered bio)
If that is a possibility, you could do a 90/10 before you start to check?
Or keep the dose low on S1, and the error will be taken out by the test at the end of S1.
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No quantitive data on the glyc. wash given (it's a dark art anyhow).
Try 16% and 5 g/L koh for S1.
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Ta.
16% of 80% or of 100%?
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16% for the whole.
The calculator thing you're using will work it out... ;)
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So I tried using less methanol. I make 90L batches and today I used 11L for the first stage and 3L for the second stage which is 15.5%. I recovered 1L of methanol, although it may also contain some water because I did a pre wash. If I reduced the methanol by 1L to take out the bit I recovered I would be putting in 13L in total. 13/90 = 14.4%. Next time I'll give it a go with those proportions.
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I also did a 90 ltr batch on friday using the same ratios 50 lts rapeseed and 40 lts palm, but i didn't do the pre wash.
Made a nice thick emulsion the moment i started the acid wash, so added 8 ltr of reclaimed meths and left overnight. next morning dropped acid wash, put back 20ltrs glyc from 1st stage and did a pre wash, the batch is now in settling tank bubbling of the excess meths.
In retrospect i should of known that i had excess catalyst when i dropped the glcy as it was frothy.
they say that you learn from your mistakes :-[
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I have just successfully run a 160L batch.
Good oil not dried or glyc washed.
S1. 16l meth 700g NaOH 1 hour mix with two eductors and two tam 105 pumps at 65C. Fallout 40%
S2. 4L meth 1200 ASM. 1 hour mix. Fallout 2% which is about what I normally get.
So about 21L meth for 160L is about 13%. I have not demethed but am bubbling for 24 hours.
Depending on the final result I will be using this method again as it saves time and energy with the final amount of meth used the same as I would normally use.
Next time I will reduce the first stage to 14L and see how it goes. I will also try to reduce the mixing time by taking more samples.
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A good result, very similar to mine.
There's a substantial time saving loosing the demeth.
Next batch, I'll try at lower than my usual 64C.
At whatever temp. the venture will suck in the methoxide. At 50C we might see some action...
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So I tried using less methanol. I make 90L batches and today I used 11L for the first stage and 3L for the second stage which is 15.5%. I recovered 1L of methanol, although it may also contain some water because I did a pre wash. If I reduced the methanol by 1L to take out the bit I recovered I would be putting in 13L in total. 13/90 = 14.4%. Next time I'll give it a go with those proportions.
I ditched the pre-wash a long time ago. If one minimise soap making by method, I never found it had much benefit.
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I ditched the pre-wash a long time ago. If one minimise soap making by method, I never found it had much benefit.
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I still find the prewash worthwhile. I stopped doing it for a few batches because I wanted to reuse the recovered meth, but that's not such an issue if you just put in less to begin with! The batches that it did without a prewash still cleared ok by settling, but that just means there'll be more soap to clear out of the settling tank when I get round to doing it.
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I've done many batches this way now and I'm going to stick with this process because it's quick for a two-stage, as well as methanol and energy efficient (another 14.4% meth + crystal clear 3/27 today!).
Not a sign of waxing of any sort, which I was getting even in summer using WBD (a process I've sworn by for years now, so this is bit of a turn up for me!)