Biopowered - vegetable oil and biodiesel forum
Biodiesel => Chemistry and process => Topic started by: Bio-boy on June 20, 2015, 01:51:44 PM
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Just a question in relation to the calculator on this site and it is with regards to the % methanol in the calculator and the figure quoted.
For example:
If you wish to use 20% methanol by volume for say 100L WVO that would equate to 20L of methanol yet the calculator states 16L???
Is this a flaw in the calculator?
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I dont know about the details of the calculator, but...
my feeling is that, if you used 20% on s1, that, in itself, may cause issues with the glyc dropping (aside from just being wasteful)
I use 10% for both stages. Makes calculations very easy also! : )
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Julian does your process include a glyc wash?
I don't glyc wash but have been using the no-titration calculator to good effect. However, it would appear that 20% in the calculator is actually 16%. However, I would be keen to hear your process as 10% for stage 1 and 2 would save me even more methanol.
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The calculator takes 80% of the "Methoxide by volume" figure as the methanol volume for stage 1. That must be from the 80/20 split for two-staging. Then if you have fallout in the 10/90 test the other 20% is used for stage 2.
If there is a better way to present this, or we're happy to use a fixed 16% for stage one and 4% for stage 2 then we can drop the "Methoxide by volume" box altogether. Opinions welcome.
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Now I am confused - although that doesn't take much.
My interpretation of the calculator I think is incorrect. This is how I interpret it:
130L WVO - add 20.8L methanol to 910g KOH (7g Base) and introduce to reactor. React for 1.5hrs and then allow glycerol to drop for 1/2 hour and complete a 10/90 test then drain glycerol. Input drop out figure into calculator (for example 2ml) which equates to an additional 5.2L and 182g of KOH. React for a further hour and then retest using 10/90 test and hopefully this should give a clear pass.
Is this correct?
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Julian does your process include a glyc wash?
I don't glyc wash but have been using the no-titration calculator to good effect. However, it would appear that 20% in the calculator is actually 16%. However, I would be keen to hear your process as 10% for stage 1 and 2 would save me even more methanol.
Yes. But, of course, the glyc is hardly full of excess chem either.
I did try, a couple of batches back, adding some caustic to the glyc (dissolved in a tiny amount of meth) as it seems like a good idea... Im not sure it made much difference though, but then my oil is not all from the same place anyhow.
If you use no-titration with variable oil, you need to get a 'feel' for what's what, else you can over / under do things (eg, if you know its manky oil, maybe increase the s1 catalyst a bit etc)
I generally go for 10% / 5g ltr of unconverted on each stage. Others do the same, with good results.
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Do you pre wash with glyc?
How often do you get a 100% pass following the 2nd stage using the quoted %'s and how often do you require a 3rd stage to obtain a complete reaction?
I will be trying 10% and 5g base for my next batch to see how it fares in comparison to my current 16% and 7g base.
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original post by julianf
Yes. But, of course, the glyc is hardly full of excess chem either.
I did try, a couple of batches back, adding some caustic to the glyc (dissolved in a tiny amount of meth) as it seems like a good idea... Im not sure it made much difference though, but then my oil is not all from the same place anyhow.
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The enhanced glycerol pre-wash can make a big difference, but we need to put it into perspective. The idea is to neutralise the FFA's 'in the prescence' of glycerol. This means the water produced from the neutralisation reaction plus any excess water in the oil will be absorbed into the glycerol. You will then in theory be able to complete the reaction in one further stage, using base amounts of chemicals.
Of course to do this pre-supposes you need to titrate. Also, depending on how much glycerol you use for the pre-treat, a 'normal' glycerol pre-treat is not going to neutralise oil that (say) titrates at 4.0
What I have found is that with my oil (titrating at 1.0 or thereabouts) just adding methanol to the glycerol will neutralise the FFA's and usually results in a 10/90 test of up to 20% conversion. The reason I only add methanol is that the residual chemicals left in the glycerol are biased in the favour of the catalyst. How do I know this? a Canadian guy on Infopop who used to advise a commercial producer ran some tests on enhancing glycerol with methanol and found it worked.
So, thats oil that titrates at 1.0 If your oil titrates at greater than that then to neutralise the FFA's the glycerol will also need some KOH. Probably 1.0 gm/litre for every 1.0 titration greater than 1.0
A while ago someone on here was processing oil that titrated at over 10.0 He was getting a yield of 68%. After he tried the enhanced glyc wash his yield went up to 88%.
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Do you pre wash with glyc?
How often do you get a 100% pass following the 2nd stage using the quoted %'s and how often do you require a 3rd stage to obtain a complete reaction?
I will be trying 10% and 5g base for my next batch to see how it fares in comparison to my current 16% and 7g base.
I always glyc wash and NEVER have to do a 3rd stage.
I use 15% and a 3g base but I do use ASM.
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Yes Jim, but lets put this into perspective. After all you were one of the members that set me on the quest for min chemical usage. There is a world of difference between the mixing efficiency of the things that you and I use and an 'average processor'.
Is it 2x pumps and 2x 2stage eductors you use?
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Is it 2x pumps and 2x 2stage eductors you use?
2 x 2stage eductors???????? now come on there, I've got 3 of the little buggers and a Squirrel.
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Is there a way of working out the titration value of WVO without the need to titrate the WVO following the % conversion of stage 1 of a zero-titration reaction?
Following todays reaction I saw .7ml fallout from stage 1 using 16% methanol and 910g KOH. I'm sure there is but I'm not intelligent enough to work it out. I know its pretty easy to just titrate a sample but thats not the point. I'm curious about the correlation of the two types of calculations/reactions.
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You don't have to worry about the acid value of stage two as it should neutral, you only need enough CATALYST to complete the conversion.
You could probably get away with 3g/ltr in stage two.
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You don't have to worry about the acid value of stage two as it should neutral, you only need enough CATALYST to complete the conversion.
You could probably get away with 3g/ltr in stage two.
I appreciate the above but I was simply wondering if there is a method without titling your oil of working it out using the results of the 10/90 test following stage 1? I know it does't matter but I'm just curious.
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What will a titration after stage 1 tell you ? As Jim says you will have neutralised the fatty acid so what you are left with is basically new oil. You just need to know how much is left to convert which is what the 10/90 tells you. Then use the base for whatever chem you use. After a 10/90 of the 2nd stage with a little experience you will get to know what base to use to get a good pass.
By all means do a titration after stage 1 and let us know what it is. I haven't a clue, not even of any of my oil for the past 2 years.
Been thinking about this and you might even get a negative reading after stage 1 due to the soap production screwing up any positive acid reading. Just like doing a soap test but you will be using the wrong Chema to get a reading.
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I have found that if I multiply the catalyst amount by 1.5 then I get a clear pas on the second stage. If I use the amount given by the calculation I always fail to get a clear pass.
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I have tried to titrate after stage 1 many times (or as i now call it the enhanced glycerol pre-wash) and it can't be done as the oil is already alkaline. This is exactly what Manfred is saying, and lets face it, if after adding stage 1 chemicals the oil was still acidic there would be something seriously wrong.
Bio Boy, The base amount of catalyst you will need after stage 1 will vary depending on your processor/pump efficiency. From recent tests I have done using the tam 120/eductor I have found my base amount to be around the 6.7/6.8 gms KOH region. Whereas using a processor with a weak pump can give results of over 8 to 10 gms. These figures are without adjusting for KOH being only 90%.
So every processor has it's own base amount. When you calculate the amount of unreacted oil for your stage 2 chemicals you will get to know what the base amount is for your set-up from experiance.
The base amount was calculated years ago by tests using new oil and thats where the 5.0gms NaOH/7.0gmsKOH was first derived from.
Again from recent testing I have done, new oil still titrates, nor is it dry. Maybe thats why my testing figures are below base levels.
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I have found that if I multiply the catalyst amount by 1.5 then I get a clear pas on the second stage. If I use the amount given by the calculation I always fail to get a clear pass.
That seems a massive o/d of catalyst, doesn't it lead to making masses of soap?
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I have found that if I multiply the catalyst amount by 1.5 then I get a clear pas on the second stage. If I use the amount given by the calculation I always fail to get a clear pass.
That seems a massive o/d of catalyst, doesn't it lead to making masses of soap?
The 1.5 x is only for stage 2 so a relatively small amount, apart from that all h2o will have been removed in stage 1, the only h2o present in the second stage will be that generated in the methoxide.
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Sorry for any confusion guys. What I am trying to put across is if it is possible to utilise the results of the 10/90 test following the stage 1 process to identify the quality of the WVO. I don't mean titrating it following the 1st stage.
For example:
My most recent batch......
Stage 1 - 130L WVO 20.8L Methanol 910g KOH resulted in 2ml fallout (10/90 test)
Stage 2 - 5.2L methanol 182g KOH result clear pass 10/90 test.
So the total KOH used for the whole process is 1092g which if using the titration process rather than the no-titration process would equate to 1092/130=8.4
Therefore would I be right in thinking that the oil would have titrated at 8.4-7(base)=1.4
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No, you're over analysing a rather simple process.
If you're getting a crystal clear final 10/90 why worry how or why it happens, just stick the bio in y'jam jar and enjoy the benefits.
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I have found that if I multiply the catalyst amount by 1.5 then I get a clear pas on the second stage. If I use the amount given by the calculation I always fail to get a clear pass.
That seems a massive o/d of catalyst, doesn't it lead to making masses of soap?
I don't think so. I only multiply by 1.5 if the fall out is below 1ml on a 10/90.
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No, you're over analysing a rather simple process.
If you're getting a crystal clear final 10/90 why worry how or why it happens, just stick the bio in y'jam jar and enjoy the benefits.
I'm just curious and wishing to develop my understanding further.
I see to have mastered the no-titration process. Clear 10/90 pass today, virtually no soap and only 3 washes required to achieve the perfect 50:50 test.
Can't wait to get my new plant operational. :)
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I do 100 ltr batches, I use 6 grs naoh per ltr with 5 litres of meth in glycerol wash then 6 grs per ltr and 7ltr of meth on 1 st stage then around 3 for 2nd stage with 4lts of meth
Total of around 15grs per litre and 16% meth. Have recently been titrating at beginning of process and its between 20 and 25.
I can only assume that by doing in stages the amounts needed are less.
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I do 100 ltr batches, I use 6 grs naoh per ltr with 5 litres of meth in glycerol wash then 6 grs per ltr and 7ltr of meth on 1 st stage then around 3 for 2nd stage with 4lts of meth
Total of around 15grs per litre and 16% meth. Have recently been titrating at beginning of process and its between 20 and 25.
I can only assume that by doing in stages the amounts needed are less.
Your oil titrated at 20-25!!! :o
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I do 100 ltr batches, I use 6 grs naoh per ltr with 5 litres of meth in glycerol wash then 6 grs per ltr and 7ltr of meth on 1 st stage then around 3 for 2nd stage with 4lts of meth
Total of around 15grs per litre and 16% meth. Have recently been titrating at beginning of process and its between 20 and 25.
I can only assume that by doing in stages the amounts needed are less.
Your oil titrated at 20-25!!! :o
Yes, some of us have to use oil that titrates at very high levels.
willbuild, the big problem with processing oil that titrates so high with a conventional base/base process is the loss of the FFA's to soap and water, which in your case will be 10 to 13%. However it's probably better (convenient) for you to do this than start to go down the route of acid esterification.
Was it you that increased your yield by some 20% doing the enhanced glycerol pre-wash?
It's a well known fact amongst more experianced brewers ( don't mean that to sound flippant) that the more reactions you do, the less chemicals you will use. Hence my min KOH usage experiments where I completed a batch with only 3.5gms/litre added KOH but had to use 7 stages to do it.
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Yes it's improved by at least 15%, have done 4 batches using this method.
I have a batch of wvo settling that I know is high that am thinking of trying caustic striping using the chart in one of your posts next week.
50% of the oil I collect is high but it use to be 75% so I'm heading in the right direction :)