Thanks for the posts,
Yes iv heard of guys both demethyalting when gly is still present and once its been drained,
so i would like to know which was is best,
It would be a huge time and energy saver if one could demeth straight after processing as the reactor will still retain plenty of heat.
I have also heard of some batches turing into peanut butter when gly and bio are heated and demethelated together, obviously i would like to avoid this, but why had that happened in the 1st place? temperature to high? batch overloaded with methoxide?
Also going back to electro static seperation, what has been the best method, large batch seperation or in-line small continiuous seperation? and how?
would really like to utilize this method of gly seperation, its brilliant!!!
Two things can happen if you demeth before draining the glycerol or washing. First, the process can reverse if the methonal level gets too low. The reaction lelies on a substancail over supply of methanol.
Second, the biodiesel soap mixture is more suscptable to forming an emmuslsion if the methanol is removed.
I personally don't recover my methanol through distillation. I prerinse with the glycerol which appears to transfer some of the methanol to the next batch. From the biodiesel I water wash it out along with the soap and then heat the batch at the end to flash any that might remain.
How can that be? When the methanol is removed the vast majority of the soap settles out, there is no need to even use water to wash it once the methanol is gone.
Yep its the only way to go in my opinion.
If you do WBD or push/pull you will not need electrostatic separation, once the methanol is removed the glycerin settles immediately and takes the majority of the soap out with it.
I bubble air through the batch over night to drive off any remaining methanol and then just let it settle. Or you could set up a wood chip filter and use it strait away.
Do some reading on here about the WBD and push/pull methods.
Hi, looking at how the post has been resurrected I have a question.
I am doing something like this for a project in my college, does any body know what is the physical phenomenon that makes this work, is it polarization? Something likes electrophoresis? Or ionization?
Thanks for your reply,
So you are not using HV for gly seperation? , purely demething your bio and allowing to settle for 1hr? before dry resin or woodchips.
Does your still operate with a vaccum?
How many HG?
operating temp of reactor/still 65 degree C?
I see it is important to keep the temp where the vapours meet the cone and pipe to be high also.
How can one see your flow rate of reclaimed methanol into it beaker, would almost want a glass blower to make a 400L glass bottle to check levels and flow rate of condensed liquid.
OK, Greg, a couple of comments about your configuration (continous flow). First, how do you connect to the liquid as it flows past the two electrodes? It it simply a metal coupler separated with PVC pipe? Is it a metal mesh? I think it is important to have good contact with all the fluid flowing by, so a metal mesh in there would be the ideal method. Even a few metal mesh plates sandwiched together would cause some fluid mixing & ensure good contact of all fluid going by.
Good advice here with the mesh stuff. I have used the metal plates before and they don't work out quite as well, but if you are in a pinch, its not the worst thing in the world.
Jon, I do not believe that you or anyone can make ASTM D6751 quality BD where the only method of washing (removing soap and other impurities) is settling. And I personally do not have unlimited time to wait. So if you water wash, the chance of producing an emmulsion due to agressive washing increases when you remove the methanol first.
Perhaps this is not your method, but it is a valid method.
Are you basing that on anything? What am I and many others missing then? If we can pass all the available homebrew test methods such as, phlip, 3/27 and soap titration, from just demething and settling, then what part of the ASTM test is going to fail, in your opinion, (or evidence)?
As for water washing, I have never done it so I cant comment with any experience there. I just dont understand how there could be a greater chance of emulsion when the methanol (and thus most of the soap) is removed? Perhaps because the soap is forced out of the biodiesel more of it mixes with the water and thus creates a bigger emulsion? Just looking for answers.
As you demeth the biodiesel you can see the pure white soap clumping up and settling out.
Here is an example. This is a vigorous shakem up test done on my last 1000l batch. The sample is from a couple of days after processing and has not been treated in any way, it was drained out of the reactor and into the tote where the sample was taken a couple of days later.
Notice there is no sign of an emulsion layer and very little sign of any soap in the water. I think if I was to do the same test prior to WBD, the bottle would contain a complete emulsion, though I am only assuming as I have never tried...
Beautiful Biodiesel. Even better looking shake-em up test result!
That is nice looking BD, but a shakem test is not a recognized ASTM test and clarity is only one of the tests that BD must pass. It gives you no idea of residual methanol, soap or catylst, all of which can be held in solution. In addition the shakem up test is in effect also washing the BD. I suspect there is a small boundary layer in your test.
I based my statement on both experience and what I have read. My first and only attempt at WBD resulted in a nasty emmusion which required hot salt water to break. My favourite guide book is by Jon Van Gerpen of the University of Idaho, and it is clear in all process it discusses there is a need for a formal wash step, whether water or dry wash.
Frankly, why would you risk damage to your engine, rapid deteriation in storage or potential bacteria growth by not washing and drying your fuel?
Yes, gotta love that golden fuel eh!
All of the things you mention above are easily tested for at home and I do, and none of them have ever been an issue. Besides other testing methods, the pHLip test will test for Catalysts, Glycerins, Soaps, Acids and Aged (oxidized) fuel. You can see where I did multiple tests using the pHLip test in the WBD and GL's Push/Pull thread to determine the affects of the WBD or push/pull with and without neutralizing the caustic. Both methods were proven to make quality fuel.
I would suggest something went wrong with your procedure or method.
Yes, you need to get out the residual soap and glycerin, this can be done by removing the methanol and letting the soaps and glycerin rapidly settle out (dry wash), woodchips or resins can also be used to filter out the soap and glycerin or finally there is the water wash for removing the methanol, soaps and glycerin. All are valid methods since they all have been proven to remove the residual soaps and glycerin.
Those are all hazards of water washing your fuel, TDIguy. Not drywashing hazards. I would never risk damage to my engines, that's why I am so anal about quality testing.
Using water to wash an engine fuel is far from ideal on many different levels, and Van Gerpen would agree. See a paper authored by one of his students here: http://make-biodiesel.org/imag...20of%20biodiesel.pdf
Here is a snippet from it:
One day water washing will entirely be a thing of the past, mark my words! It simply does not make good sense anymore.
If you WBD and do not wait for the soaps to settle out but proceed to water wash you will run the risk of emulsion, in the same way that if you do not limit the amount of glyc getting into the wash cycle after the reaction.
Aggressive water washing is done with a fuel that is very low in soaps and that can be achieved by using a dedicated settling tank so that the glycerine stays below the drain level of the standpipe when the transfer takes place.
As Jon says though, water washing is old news. You can get much more positive results from WBD using a dry media for purification, although the time allotted for allowing the soaps to settle out after the methanol has been removed goes a long way toward prolonging the life of your dry media, whichever type that might be.
Whether the WBD method is used or the separate glyc/biodiesel purification method the most beneficial methodology is to let the soaps settle out as much as time will allow.
** Biodiesel Glycerine Soap - The Guide
- on 5 continents helping people make & sell soap from the Biodiesel Glycerine.
There is one thing that water washing can do Jon that other methods cannot.
If the water wash method is aggressive enough towards the latter end of washing and left for long enough then the monoglycerides present can be emulsified and removed.
It is suprising the amount contained in biodiesel that passes 3/27 or similar tests.
I water wash but sometimes settle and centrifuge, if using the latter the mono's will still be present.
|Powered by Social Strata||Page 1 ... 18 19 20 21|