percentage conversion for vw alh tdi and 300tdi discovery.

[simonallen]

Hi guys,
is there any chemical reason why I can't just do a single stage reaction, using the two stage calculator and leave out my second stage, then demeth and settle as per the gl system.
The cars I am running on my bio are veg munchers, and have been running perfectly happy on 50/50 with good quality bio and filtered wvo (1 micron).

I would like if I can, to get rid of my wvo filters and just do the bio process. I know that it's best practice to push the reaction to a complete finish, but it would save me time if I could just do a single reaction then settle and dry wash. Would this cause excessive soap? or any other problems that I'm not aware of. I'm thinking I will be getting a good 60/70% conversion minimum which is more than what I am effectively running them on at this moment in time and both are pretty happy. I also glyc wash my oil before reacting.

your thoughts would be appreciated 

[julianf]

Mono and di glycerides can, iirc, be higher melting point than the tri, or the methyl ester.

In layman's terms, hmpe issues.  But try it - might all work out fine?

[simonallen]

Ok. Is there any way I can force/encourage hmpe to form if I did a test batch and left it for x amount of time in a 60l drum outside? Before I run it in the cars etc.

I know it sounds like i dont care about the process but I do. It's not a problem to chase as much a conversion as I can, but time is of the essence for me. Filtering I can just fill the bags and leave it, whereas bio is a lot more labour intensive but I have to buy petrol to thin it out if I run veg and I'd much rather "stick it to the man" and process all of my fuel than line Camerons pocket ;-)

[Dickjotec]

Generally speaking I do the first stage of a two stage and accept the fallout for our cars. I can and sometimes do complete the second stage if there is too much fallout.
My process
Make 25l Meth (12.5%) with 900g NaOH the day before so it has time to dissolve.
Glyc wash 200l of oil while heating to 40-50C
Add the methoxide via Venturi over about 5-10mins.
Continue heating to about 65C while mixing with two tam105 pumps. (I have two educators but ATM they are blocked so the processing is not as fast as it could be.)
Check fallout on 5/45. When less than 1ml settle glyc and decant bio.
If necessary add meth + ASM to improve reaction but rarely need to.
Decant and bubble of 24 hrs.
Settle for 2+ weeks.
Check for soap with 50/50 test.
Filter and send to storage tanks till used.

All cars would be OK on veg. The Delica has done 50+ thousand miles on this fuel, with an occasional batch of clear pass bio.

[simonallen]

This sounds promising! Do you get problems with hmpe's and how do the cars run in the colder weather?

I have a batch going now. I have done it with 13.2l of methanol (16%) and 770g (7g/l) of koh. This is a batch of 110l as that's all I had to hand. I have done the first stage reaction and it's currently demething through my venturi. Settling time is no problem. It will also be 1 micron filtered before use.

Guess I will find out in the next few weeks how I get on and what it runs like. Thanks for the tips guys

[Dickjotec]

I did have a problem with something which could have been hmpe a while ago but reducing the meth percentage seemed to cure it though it could have been oil contamination or something compleatly different. It came from nowhere after 7 years brewing only happened for about 5 consecutive batches then disappeared! (Strange hobby we have!)
I have no problems in winter but do add misfuel when cold and increase the percentage as it gets colder. I have used the Delica in  temps on the  outside temp gauge down to a registered -15 or less.
As suggested above give it a go. Test your fuel in the freezer, down to -3 or  -4 with no addative, use a thermometer, and see what it looks like.

[Julian]

To check for HMPEs chill the bio slowly ... fridge at circa 2°C should be fine, but often they can form at higher temperatures.

We should have a wiki page on this but there was some doubt as to exactly what they were and I think we shied away from it.  What ever they are we should really make a page as they exist and can cause big problems if they form in the car.

I posted quite a lot of experimental info on the VOD several years ago, but I think much data in HTML tables was lost when HTML was disallowed.  Just looked and all my VOD book marks have been erased, but I did magage to find the thread ... http://www.vegetableoildiesel.co.uk/mybbforum/showthread.php?tid=16876&highlight=controlling+the+little+buggers  (now I've found it I'll see if I can rescue some of the data for the wiki).

Extract from the thread ... here's a photo of what I swabbed out of the Disco tank one winter.



Julian ... are you saying HMPEs are mono and di glycerides?  I'd never thought of them as that, but I guess it could be tested by chilling a sample of partly converted bio and comparing it with a fully converted sample from the same batch.

I've had collection of HMPEs in a jam jar from last winter which have survived all summer without melting.  I might try a 3/27 test which was suggested some time ago.



Anyhow, Simon, if you just want ti do one reaction why do the first half of a two stage?  Why not just do a single stage with all the chemicals.  You should get a far better conversion for the same effort.

[Head Womble]

Anyhow, Simon, if you just want ti do one reaction why do the first half of a two stage?  Why not just do a single stage with all the chemicals.  You should get a far better conversion for the same effort.

I was thinking the same thing.

Go back to a titrated single stage reaction, it's what we all did back in the day.

[dgs]

Quite a few people still do single stage with or without titration, to simply reduce labour times. Also a lot of brewers arn't over bothered about getting complete conversion (depending on vehicle)

I wouldn't be too bothered about hmpe's as long as your feedstock is liquid. preferably liquid at the temperature you are going to use the bio at.  What is more important is the purification. If 'say' you had 95% conversion the crude bio would be difficult to water wash, so you need to de-meth and settle. Then check with a 50/50 or preferably a soap test. By all means then filter through oak chips or similar and filter to at least 5 microns.

I was thinking of doing a similar thing for the fuel for my Estima and dispatch van, but only converting to about 70%.

[Chug]

I've used 'bio' made from reacting just enough to get the glyc to drop, which is hard to filter even after demeth and settle for days due to being thicker with mono's and di's and soap probably,
right up to clear n bright pass 3/27 bio, which obviously works great,  but IMHO and experience over 11 yrs of trying to make bio out of all sorts of crap and trying different methods/experiments, as long as the wvo is converted to at least 75 - 80% bio then it will be fine for use in all but modern high pressure diesels.

[simonallen]

Superb news! I didn't even think about using a single stage setup tbh, I don't have the stuff to titrate but can get hold of it and will do so now. I guess that because I am getting used to the two stage calculator it was just the way I thought about. I'll get some titration stuff and do it that way from now on without chasing a full reaction providing I don't get any hmpe problems with my test samples.

On another note, I've just got round to using the first bit of liquid soap I made, holy hell! Good stuff isn't it?

[simonallen]

All of my feedstock is liquid by the way, I've deliberately.stayed away from solids as I have built up my collections with a view to just filtering it and running it.