sorry, please disregard my last statement. in my morning pre-caffeine stupor, i forgot about the miscibility of water/methanol.

I've read through much of this thread and am in the process of building my own but I honestly don't care much about the methanol recovery at this point. I'm more concerned with methanol extraction from the bio and glycerin for sake of soap fall out and lack of washes. What about hooking up an air operated venturi (cheap auto a/c vacuum "pump")? It doesn't have any moving parts and wouldn't be affected by the methanol rich vapor. This would eliminate the entire second vessel, condensor, heater and pump. Yes, no?

Mixing methanol with air is literally "playing with fire". Of course any vacuum pump will help demeth the BD, but the main advantage of Graham's oil vacuum system is that it minimizes the risk of a fire. Furthermore, demething is the complicated part of the methanol recovery process by far, so, once you are doing it, not recovering the methanol doesn't make much sense.

quote:

Originally posted by bernyjb:
Mixing methanol with air is literally "playing with fire". Of course any vacuum pump will help demeth the BD, but the main advantage of Graham's oil vacuum system is that it minimizes the risk of a fire. Furthermore, demething is the complicated part of the methanol recovery process by far, so, once you are doing it, not recovering the methanol doesn't make much sense.

I agree that is not as efficient as recovery but for simplicity sake I'd like to start of just demething and then rework to recovery if I feel it's worth the extra equipment and space. I also do agree that venting methanol into the environment isn't the best way to go but it's hardly "playing with fire" especially when there isn't a form of ignition (ie. flame, spark, electricity) anywhere near the output of the venturi. Am I wrong?

quote:

it's hardly "playing with fire" especially when there isn't a form of ignition (ie. flame, spark, electricity) anywhere near the output of the venturi. Am I wrong?

In a perfect world you'd be absolutely right. Unfortunately, in the real world, accidents DO happen (and there have been plenty of threads in this forum alone, testifying to it).
Of course, it's ultimately your decision. I wouldn't use it, first, because it's inherently unsafe, and second, because is not cheaper, neither to buy, nor to operate (it needs an air compressor). But again, that's just my opinion...

Already have a compressor.

So the only safety concern is the venting of methanol fumes, which would be no different than a traditional appleseed. If handled properly the risk factor can be reduced significantly if the vent is routed to the outside with proper air circulation.

Anything else I'm missing that would affect the efficiency of the demething?

why risk your life and the life of those around you for the effort involved? There is a difference between demthing quickly under a vacuum and the traditional appleseed process. It is more dangerous. Inherently dangerous processes are a foolish path just to avoid a little effort.

I have been searching the post and Graham's website and do not see the information clearly (I am sure it is here though). Roughly how much HCL will be added for lets say a 50 gallon batch? I am only asking to find out how big a syringe I need to buy and how much HCL I will need to get from the chemical store.

Thanks
Doug

Roughly 100mls 34% HCl per 100litres of bio.

Doug, He stated that he used the HCL solution that was used to clean cement and bricks. That was about 34% conc.

Mike

Thanks Ant and Mike.

For 50 gallons or so about 184ml. I finally found a link where Graham stated .1%. Now I have a few more questions.

1. Recommendations where to buy HCL in Los Angeles.

2. Where to buy Rapeseed oil the US? I have asked a few places and they look at me dumbfounded. Canaola Oil is a bred/genetically modified rapeseed available in the US. Graham does that work as a substitute or should I find the real deal?

3. Last thing about the HCL. Is that .1% approximation measured Oil alone or Oil with the 20% Methanol added?

Thanks
Doug

PS. Anybody else have good recommendations as where to buy Chemicals in Los Angeles, please let me know.

Doug,
You can buy muriatic acid, which is HCl, at your home depot kind of stores. It is used for cleaning concrete. I am sure that it would be cheaper in a comercial use than from a specialist chemical shop.

Mike

quote:

Last thing about the HCL. Is that .1% approximation measured Oil alone or Oil with the 20% Methanol added?

I would guess that is for the amount of bio but you need to neutralise the caustic in the glycerol as well. I think it would be the same as for the amount of oil you started with. That was how you measured your caustic to begin with. But best to get Graham to confirm that.

I do not believe Graham is actually completely neutralizing the base - for the amount of HCL he is adding, it isn't even close.

Think about it, 100ml for 100 liters of biodiesel. Graham adds until he sees his indicator change color in his site glass. Graham has stated that he believes his pump is under powered for the task at hand, which implies that he is not getting optimum mixing between the glycerin and the bio, and since most of the catalyst will be in the glycerin phase, he is probably only neutralizing the catalyst in the bio (for the most part).

That is the only reasonable conclusion that i can come up with. But, this leads to another question.

Would it be really beneficial to have a substantially more powerful pump in the system that would mix things up - i kinda think that it would result in the addition of a liter plus of muriatic acid in order to neutralize the catalyst.

So, here are my suggestions.

(1) keep the underpowered pump in this part of the process

(2) Cool down alot further

(3) use KOH because the NaOH glycerin will get real hard real fast at lower temps

(4) draw a very deep vacuum so that the methanol can be distailled at the lower temps.

(5) Don't add any acid

(6) Somebody do this and test it out to see if it passes both 3/27 as well as the test for free/total glycerin.

quote:

(6) Somebody do this and test it out to see if it passes both 3/27 as well as the test for free/total glycerin

Go on then. Let us know how it goes.

Don't have one of those set ups built yet and i'm 12000 miles from home at the moment.

See...I knew I wasn't the only addict to this website. Half-way around the globe, and he is still checking the boards...
I'm sure there's a 12 step system for the website somewhere.
-Scott

quote:

Originally posted by handcuff:
See...I knew I wasn't the only addict to this website. Half-way around the globe, and he is still checking the boards...
I'm sure there's a 12 step system for the website somewhere.
-Scott

LOL
Ya let me know where to sign up!
Jon

Ok, I am buying a PID with ramp and soak - I am already in this too deep not to commit to this as well. I am well approaching $3500 on this machine. I will have a final parts list and prices, so we can break it down on where to save a few bucks. Ok but here are my final questions. Graham if you are out there, please chime in.

1. Rapeseed Oil? Can I substitute Canola Oil? If not, does anybody know where I can get Rapeseed Oil in the U.S.

2. Sulphuric acid versus HCL. I can get the muriatic acid (HCL 31%) at the hardware store but I am quite concerned about storing it in my garage with all the other chemicals - as well as any damage like rust it might cause to my tools. My garage is not large nor very well ventilated - I just put in 12" turbine vent in the ceiling two days ago - and that is all there is. The local hardware store even keeps the HCL out back because of this problem. So here are my questions:

2a. Is Sulfuric Acid any better to store? Utah BioDiesel sells it by the 950 ml plastic bottle and the BioPro machines use it so I am thinking it must be a little less caustic to store. Is this right or makes no difference?

2b. If I go with HCL, how do I store the excess?

2c. Anybody actually used another Acid in this process? No conjecture, 'cuse if not, I am using the HCL and figuring out a way to store it. Too many variables in the air at once on an untested machine (mine that is) and untested pilot (me) to change something Graham has gotten working currently.

3. What do I use to contain 184ml of HCL/H2S04 during injection. I have in my shopping cart at www.smallparts.com, 10 feet of 1/8 Tygon Tubing, ten (a bag) 1/4 NPT to Luer (syringe) Polypropylene connectors, some Luer->1/8 inch barbs,and a medical pinch flow restrictor. However what the heck do I put the HCL in while it drips in for 30 minutes? I am thinking just to get a 2 inch steel pipe, put a bell reducer on it and fill that up and put a cap on it the pipe. I hate not being able to see the flow of the HCL but... any other suggestion?

I think that is it. I will be putting the finishing touches on this weekend, so I am anxious for answers (aren't we all).

Thanks
Doug

Doug: $3500??
What did you use? Gold?

Anyways, here's a few answers:

1. Rapeseed and canola are the same. Canola is a variant of rapeseed grown originally in Canada.

2, 3, and 4. you're right about the HCL. Its vapors will rust any exposed iron or steel in a very short time. About H2(SO4) (pure), I have had it stored in my dad's workshop for a few weeks when I was a teenager, and it didn't cause any visible damage. It took HCL 2 days to leave all his tools like they'd been rescued from the Titanic.
For what other, better informed members have said a few pages back, sulfuric should be as good as HCL. The only difference I can think of is that, with sulfuric being available (and desirable) in higher concentrations, the quantities to be used would be much lower, so precision becomes even more critical.
You can store H2(SO4) in any glass jar (with a big label, please).