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Thread: Drying WVO

  1. #11
    Join Date
    Nov 2005
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    Tasmania
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    516

    Re: Drying WVO

    There is a very simple way to make sure there is no water in your oil before processing, get a decent centrifuge. They allow you to remove water and waste, then you can process it.

    I run mostly on straight vo, but make BD for starting and cleaning stuff so get the best of both worlds. Used to almost boil my oil before getting a fuge so it would process better and it did, but a fuge makes life so much easier and the rubbish and water it removes can then easily be used for processing. If you heat your oil to about 200deg, all the water will be evaporated and if you have a collector above your heater tank, that will collect the water.

    Now dirty oil is run through the fuge, into the processor, then BD goes back through the fuge, sits for a few days exposed to the sun in either summer or winter, then is ready to be used. The BD I use is normally many months old and very clear, anything in it drops out and it's rare for there to be anything but a thin film on the bottom of the drums, which is added to the process again.

    My centrifuge cost close to $2000 years ago and is pretty primitive, only able to process about 100lt a day safely and with a few clean outs. Now you can get them from china for around $1500 and they process large amounts, a friend down here has one that is 3 phase 4hp and he can process 1000lt a day without stopping it, as it self cleans and can be found on ebay. That will be my next purchase if I can figure out how to run it without 3 phase properly (off grid), have a motor controller, but not sure if that will cope with 4hp so will have to do some research on that.
    Last edited by Alga; 5th December 2016 at 11:01 AM.

  2. #12
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    Re: Drying WVO

    Hi WesleyB,

    Quote Originally Posted by WesleyB View Post
    "1 KG KOH in 20 litres of methanol produces 320 gms of water (1.6%) plus any water in the methanol."
    Not exactly. Most KOH is not 100% pure.
    But if your KOH is 90% pure then 1 kilogram equals 900 grams of KOH, which is about 16 moles, not the higher amount assuming 1000 grams of KOH.
    900 grams of KOH would produce 288 grams of water if the reaction proceeded 100% with methanol to produce methoxide.
    Do not forget that the "contaminant" in KOH is Water (H2O).
    So if your KOH is 90% purity, it contains 10% H2O which would be another 100ml of H2O per kg of KOH used in the reaction.
    So in your above case that would be 288g H2O from the reaction and another 100g of H2O as contamination in the KOH for a total of 388ml H2O per kg of KOH used in the reaction



    But the reaction does not proceed 100% where Hydroxide ion from KOH plucks the hydrogen from the hydroxide on methanol, producing water and methoxide ion.
    I don't know the percent the reaction forms at equilibrium. I remember reading that a person said only 5% does the potential reaction proceed to form methoxide.
    Thank you for explaining this part again, I had forgotten it.
    So working with the above figures, if only 5% of the KOH is actually converted into Potassium Methoxide that would be 5% of 288g H2O which= 14.4g H2O from the reaction and 100g H2O as the contaminant in the KOH.
    A total of 114.4g H2O
    Last edited by tillyfromparadise; 5th December 2016 at 11:41 AM.

  3. #13
    Join Date
    Sep 2005
    Location
    WA
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    4,176

    Re: Drying WVO

    Thanks all for your contributions.
    To summarise:
    - Heating the oil and exposing it to oxygen will have an impact on its FFA levels (higher temp , more O2 & time all contribute to an increase in FFA).
    - Acid can be used to dry the oil and if used with part of the methanol for the reaction can reduce the oil FFA. The wet acid needs to be removed before using more Methanol and Caustic to complete the Acid-Base biodiesel process. Please do more research to determine if this is for you. (Added safety issues and costs)
    - Byproduct from previous biodiesel reactions can be used to remove most of the water from cooking oil.
    - The Biodiesel process does produce water when KOH or NaOH is mixed with Methanol (or Ethanol)
    - 90% KOH is 10% water, so there will be water in the biodiesel reaction anyway.

    - If you have few bubbles in a HPT, then you should be fine making biodiesel with that oil (at least when using Methanol rather than Ethanol).

    Go for it horseflybiodiesel.
    Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

    Current Vehicles in stable:
    '06 Musso Sports Crew Cab. Running on used cooking oil with 5% to 10% misfuel.
    '2014 Toyota Prius (on ULP)


    Previous Vehicles:
    '90 Mazda Capella. (2000 - 2003) My first Fatmobile. Converted to fun on veggie oil with a 2 tank setup. Died when supercharger stuck at max boost for weeks. Stretched head bolts.
    '80 Mercedes 300D. 2 tank conversion [Sold]
    '84 Mercedes 300D. 1 tank, no conversion. Replaced engine with rebuilt OM617A turbodiesel engine. Finally had good power. Donor for current Fatmobile coupe. (body parted out and carcass sold for scrap.)
    '99 Mercedes W202 C250 Turbodiesel (my darling Wife's car)[sold]
    '98 Mercedes W202 C250 Turbodiesel (my car)[sold]
    Parts Car C220 1993 SOLD.
    '85 Mercedes Benz W123 300CD Turbodiesel single tank using 95% used cooking oil and 5% to 10% misfuel (where someone had filled diesel vehicle with petrol).


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  4. #14
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    Dec 2006
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    Townsville, North Queensland
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    Re: Drying WVO

    Quote Originally Posted by Alga View Post
    That will be my next purchase if I can figure out how to run it without 3 phase properly (off grid), have a motor controller, but not sure if that will cope with 4hp so will have to do some research on that.
    Being 4 HP it's gunna suck a fair emount of electrons on single phase, but ti can be done with the right VSD unit.

  5. #15
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    Re: Drying WVO

    Just to clear up one point.

    Acid Esterification (AE) is only used for high titration oil to reduce the titration of the oil by esterifying FFA's into biodiesel, it is not used to dry oil.
    In fact, you need to have the oil already dry before performing AE because water is a byproduct of the esterification and if enough water is present it will stop the esterification reaction

  6. #16
    Join Date
    Dec 2016
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    York UK
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    Re: Drying WVO

    Hi Wesley,

    I think the chemical you are referring to is Sodium (or Potassium) Methylate. As you say it is anhydrous and when mixed with methanol also 'consumes' water that is in the methanol, so gives a totally water free methoxide.

    Under these circumstances as long as the oil is dry yeilds of over 100% (by volume) can be achieved with reduced soap production.

    Many of us here in the UK use it. One drawbrack is that the glycerol sets 'like a brick'. I use various combinations of all three catalysts depending on time of year. I find it gives the best combination of yield, economy and liquid glycerol.

  7. #17
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    Re: Drying WVO

    Hi smithy, welcome to the forum!

    Quote Originally Posted by smithy View Post
    Hi Wesley,
    I think the chemical you are referring to is Sodium (or Potassium) Methylate.
    As you say it is anhydrous and when mixed with methanol also 'consumes' water that is in the methanol, so gives a totally water free methoxide.
    Wesley is talking about making methoxide by mixing KOH with Methanol which was what you were talking about, not purchasing Sodium (or Potassium) Methylate.
    Wesley did not say it was anhydrous, he only pointed out that mixing KOH with methanol does not make the full 320g H2O per kg of KOH used in the reaction you said was produced. Wesley explained that this lesser H2O production is due to variables such as the purity of the KOH involved and how much methoxide is actually produced when the KOH is mixed with the methanol.

    Typically new methanol is 99.9% purity or greater.
    Can you explain what you mean by "consumes" when you said "...when mixed with methanol also 'consumes' water that is in the methanol"


    Under these circumstances as long as the oil is dry yeilds of over 100% (by volume) can be achieved with reduced soap production.
    There is a bit more to it than that.
    The maximum theoretical yield is about 100% by mass which, depending on the oil being used, equates to something like 104.5% yield by volume
    However, to achieve this high yield in a straight base reaction requires that the oil must also not contain any FFA's.
    FFA's do not convert into biodiesel in a base reaction, they convert into soap.

    I have noticed on other websites, people will sometimes include the biodiesel that drops out of the glycerine during a glycerine prewash as part of their claimed yield.
    Last edited by tillyfromparadise; 6th December 2016 at 08:49 AM.

  8. #18
    Join Date
    Nov 2010
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    Fort Worth, Texas, USA
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    281

    Re: Drying WVO

    A few points I noticed. Free fatty acids have a carboxylic acid functional group on the end of a carbon 12 to carbon 22 or so chain. A carboxylic acid is a carbon bonded in this case to another carbon ( the long chain connection) and to two oxygen atoms. One of the oxygen atoms has a double bond the other has a single bond. The single bond oxygen also has a single bond to a hydrogen, being a hydroxide (alcohol group). The free fatty acids have a functional group (caroxylic acid) that is the same as vinegar ( dilute aqueous acetic acid). The issue about that as it relates to this issue is water is strongly attacted to the acid group on free fatty acids. So a centrifuge will not remove all the water, hydrogen bonded to the carboxylic acid end of a free fatty acid molecule. Sodium methylate or sodium methoxide (a chemical may have several names designating it that are valid) is an anhydrous solid, but I believe it ignites when exposed to air. So it is sold I believe in solution in anhydrous methanol. Being dissolved in anhydrous methanol it is not as dangerous. Using solid sodium or potassium methoxide would have to be done in a glove box under inert atmosphere, which would be expensive. So the without water (anhydrous) chemical is available somewhere in the United States as an anhydrous (without water) alcohol solution, so that it can be carefully used outside a glove box with a nitrogen atmosphere inside it. Tilly I did not know the 15% percent inpurity in my KOH is water. I'll look at the assay printed on the label of my bottle when I get home later. Free fatty acids are a product of hydrolysis, that's water plus vegetable oil triglycerides yields free fatty acids plus mono, di or glycerine. The water inserts it self at the bond between the fatty acid and glycerine to produce two different molecules. After wards the water does not exist. The molecule has separated at the atomic level. OH- goes with the glycerine, H- goes with the free fatty acid. A general priniciple in organic chemistry that for every 10 degrees centigrade increase in an endothermic reaction as opposed to an exothermic reaction (heat given off) a doubling of the reaction rate occurs. So the lower temperature vaccum assisted removal of water from oil will allow less free fatty acids to form during drying. The longer the wet oil is kept hot the more hydrolysis will occur and the higher titration results. Maybe centrifuge the wet oil then using a flash evaporator then acid base proceedure might be best but might not be cost effective and a lot of equipment and a lot of trouble. Magnesium silicate or wood chips might be the most cost effective way to remove almost all the soap produced.
    Last edited by WesleyB; 12th December 2016 at 07:06 AM. Reason: spelled one word wrong , added two words I left out

  9. #19
    Join Date
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    BC canada
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    Re: Drying WVO

    Yum.....so bubbles are ok? hahaha, man do I have a lot to learn about this hobby

  10. #20
    Join Date
    Dec 2016
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    York UK
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    Re: Drying WVO

    About a year ago I did a process using KOH methoxide that had beed dried using CaO (quicklime) The yeild was noticeably higher and the amount of Potassium soaps were very low. The big disadvantage was that some calcium soaps were produced during the process which were difficult to remove. I ended up filtering the dried biodiesel 3 times through hardwood to get rid if the calcium soap.

    For convenience I now use a blend of Potassium and ASM (anhydrous sodium methylate) whenever I can, using as much ASM as is practical for the time of year. At the moment I can't use any ASM as using just 1/3 will result in solid glycerol. In Summer I can go up to 2/3 ASM and 1/3 KOH where the glycerol still remains liquid.

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