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Hello Joe.
If you are trying to recycle the surplus
methanol you should be aware of this:
MeOH
+ KOH → MeO ‑ + K+ + H2O
Methanol
and potassium hydroxide will form water. That is your first water source. The
second is the water content of the fresh methanol which should be below 0,5%.
The third water source is the oil, max water content 0,5%. And if you add 1kg of
KOH you can expect it form 0,322 kgs of water as it dissolves in the methanol.
So for a batch of 1000 kgs, these are the actual water contents:
Oil:
5 kgs
Methanol
: 1kg
KOH
(20kg): 6,45 kgs
12,45
kgs of water = 1,25%
So
now you can understand why it can be necessary to dry the oil. To
decrease the water content further I suggest that you purchase ready-made
anhydrous catalyst, such as Potassium or Sodium Methoxide. In this case the
surplus methanol will have a low water content and will be recyclable. For the
water in methanol tests I can only say that this gravimetric method of yours is
difficult. So far there is no simple quick and reliable method to do
this.
Best
of luck to you !
Jan Warnqvist
AGERATEC AB
+ 46 554 201 89
+46 70 499 38 45
----- Original Message -----
Sent: Tuesday, August 22, 2006 4:15
PM
Subject: Re: [Biofuel] Water content -
was tirating a virgin oil
Jan;
Further to my post from yesterday regarding the
0.5% water in oil as a limit; I am assuming that this percentage relies
on fairly anhydrous methoxide, and therefore is the maximum water that the
process can tolerate. Is this a safe assumption? And if so would it be
safe then to assume that if the oil is very dry the same absolute amount of
water could be present in another source? I am asking because I am
working on methanol recovery now. I can dry my oil quite well with
vacuum and heat but recovered methanol always has significant water. If
I assume methanol is added at 20% of oil volume then the same absolute volume
of water present in the methanol can be 5 times higher i.e. 2.5% instread of
0.5% of oil volume? Is this correct? If so then I need only dry my
methanol to 97.5% to get good results with very dry oil. I would
appreciate your thoughts on this.
I have purchased a hydrometer in the
0.790 to 0.900 range so that I can test the water content of recovered
methanol. The hydrometer is calibrated for 15 degrees C which is cooler
than room temperature. Also there is the problem that if I add 50 ml
methanol and 50 ml water I don't get 100 ml of liquid! Rather than try
to compensate the readings what I have decided to do is start with pure
methanol and add small amounts of water and record the readings at room
temperature to produce my own table based on percentages by volume. I
will post these results so that others can benefit from it. My first
test which was a mixture of methanol recovered from fuel mixed with methanol
recovered from glycerin cocktail measured 0.813 at RT. That's a lot of
water. Sigh.
Stay tuned for more.
Joe
Jan Warnqvist
wrote:
Hello Emre, Rafal et al.
I have to say that I partially disagree with some of your statements. The
limit of FFA for a flawless trans-esterification is drawn at 5mg KOH/g of
oil. Any value above will demand pre-treatment of the oil. It is always
important to check the water content, which should be below 0,5%. Try to get
hold of a water-in-oil test kit for quick determination.
If we are talking about the EN standard, it is always necessary to process
the oil/catalyst/methanol mix for 90 minutes to obtain the right values for
tri- di- and monoglycerides. And - this assumes that you have correct
stochiometric conditions and no methanol losses during processing.
As for the phophatides and the chlorophyll compounds, my experience is that
these are not very important for the processing result, unless the values of
these are extremely high (thousands of ppms). If so, the oil is usually very
dark. Totally refined oil, on the other hand, may have preservatives added,
and some of these will eat catalyst. So, good oil quality is a tricky thing.
Best of luck to you !
Jan Warnqvist
AGERATEC AB
+ 46 554 201 89
+46 70 499 38 45
----- Original Message -----
From: "EMRE ELMAS" <[EMAIL PROTECTED]>
To: <biofuel@sustainablelists.org>
Sent: Sunday, August 20, 2006 10:15 PM
Subject: Re: [Biofuel] tirating a virgin oil
Dear Rafal,
First of all, as long as you use cheap oil you should always be prepared
to
deal with much more FFA and water than it should normally contain. I think
your emulsion problem occurs as a result of highly contained water. If
that
is the problem you should first dry the oil then process the reaction.
Also if you use crude oil you should be very careful about the chemicals,
such as lesitine, in the oil. So always try to use degummed oil, if you
have
to process crude oil.
Another thing is, as you probably know, approximately 95 - 97 % of the
reaction is completed in the first 35 minutes, so you do not have to wait
for 2 hours. Also the alcohol boils at 65 C and the closer you get to that
point, the more alcohol you will lose at the time you need it the most for
the reaction. This prevents you to complete the reaction 100 %.
As I mentioned above if you just watch the content of water and the other
impurities in the oil you will be fine.
Hopefully the information works for you. I am looking forward to hear from
you soon.
Best wishes,
Emre ELMAS
Mobile: +90 533 517 72 45
From: Rafal Szczesniak <[EMAIL PROTECTED]>
Reply-To: biofuel@sustainablelists.org
To: biofuel@sustainablelists.org
Subject: [Biofuel] tirating a virgin oil
Date: Sun, 20 Aug 2006 19:31:26 +0200
Hi,
Recently I've came through problems with testing a cheap virgin oil
in my test processor which every time ended up with incomplete reactions
(emulsion problems). I did make the process longer (2 hours) and at
higher temperature (60-63 degC) - still nothing, though by product
separation is very nice.
Today, I tried to titrate the oil and - to my surprise - it took 0.925ml
of KOH solution. This was my first experience with titration, so I can
also tell that the phenolophtalein solution turned pale (but noticable)
magenta for about 15 secs (as described at JtF) after 0.925ml. After
adding 1.05ml the colour got more intensive for longer time.
My main question is - is it normal in case of cheap oils ?
I suppose they contain (as other oils) some amount of FFAs, but so much ?
Additional matter is whether I got titration right. I mean, interpreting
the colours.
I'm running out of ideas what could be wrong in the process, so any
help is appreciated.
--
cheers,
Rafal Szczesniak **mir[at]diament.iit.pwr.wroc.pl
Samba Team member mi***[at]samba.org
+---------------------------------------------------------+
*BSD, GNU/Linux and Samba http://www.samba.org
+---------------------------------------------------------+
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