Andrew Morris's Post:

quote:

Also, since there have been a couple of different versions of "neurtal's numbers", can you tell us exactly how much of cat and methanol you used?

I used the most recent numbers:
First Stage
140ml methanol
3.5g NaOH + (Titration X 1.15) or
4.9g KOH + (Titration X 1.15)

Second Stage
23ml Methanol
1.5g NaOH or
2.1g KOH

Adjust base amounts of NaOH/KOH for purity

My titration was 4.5 g/l KOH @ 90% purity. This particular batch of oil had 200 gallons of beef fat from a BBQ joint The glycerine was very thick. Can't wait to smell my tailpipe. Yummm.

bio-LOGIC,

Thanks!

Can you also tell us how long you ran each stage?
Also, mixing? What do you use?
Also, temps?

Thanks again.

Andrew

Andrew's Post:

quote:

Can you tell us about the mixing you use with that size of batch?
How long do you run each stage?
Vented?

This part is very unscientific because it depends on how cloudy/rainy it is. The goal is to get it up to temp and sometime it's 4 hours and sometimes it's 2 days (this much oil holds heat very well over night). Now that summer is arriving I can heat 400 gallons in 4 hours. In July, I might be able to do better. I also have 6 more solar panels I can add to the equation.

That said, as I heat, agitation happens because I'm pumping in and out of the tank to the solar panels. There is 1 pipe that goes to the solar panels and 1 that returns directly to the tank. I'm afraid to pump 100% thru the solar panels because they are 3/4" and this pump does 50 gpm. I might blow something. On a batch this big, a blow out would be very expensive and a huge mess.

So, I always allow oil to flow thru both pipes. Also, I've noticed that if I allow a slow flow through the solar panel side the oil gets very hot allowing for higher temp/less agitation on that side. Possibly effective to the reaction?

As far as vented...The lid is vented and I'm thinking of finding a cork to stick in it. I don't want to create a deviation between the atmospheric pressure and that inside the tank, but using neutral's numbers you can't afford to have a loss of methanol thru evaporation, or to have any water in the oil, which is why I do the glycerol oil polish.

Andrew's Post:

quote:

Can you also tell us how long you ran each stage?
Also, mixing? What do you use?
Also, temps?

It all depends on the sun, so agitation times vary. It'll be different every time but I think consistant results can be achieved.

I think the short answer to your question is this: Once it is up to temperature you can follow neutral's numbers exactly.

These are the goals:
1. Polish the oil so you've got a good start.
2. Get it up to temperature (might be fast, might be slow.)
3. Follow neutral's numbers.
I think you'll get good results every time.

For mixing I use the 50 gpm sprinkler pump.

bio-LOGIC,

Thanks again for taking the time to explain.

I get it. The time it take to heat varies a lot, depending on the weather.

So, once it up to temp., and you put in the stage one methoxide... Then, on average, how long do you need to run stage 1? Stage 2? Or, what is the range of times you run them?

The 50 gpm sounds good for a system that size.

quote:

I think the short answer to your question is this: Once it is up to temperature you can follow neutral's numbers exactly.

As far as I know, neutral did not prescribe how long to run each stage. I don't doubt my ability to get it done. I have made passing fuel with 14.5% methanol using 2 stage. What I am trying to do is to get some other data, besides my own, on the ideal length of time to run each stage.

Andrew

Andrew's Post:

quote:

Then, on average, how long do you need to run stage 1? Stage 2? Or, what is the range of times you run them?

Stage 1 agitates for 1.5 hours. I begin draining glycerine within 20 minutes after the pump is shut off. It takes a while to drain that much glycerine.

Actually, I'm not sure why we drain the glycerine at all. I'm not convinced it wouldn't work even better to leave the glycerine in the solution at Stage 2.

Stage 2 is agitated for an hour and allowed to settle overnight.

bioLogic.

quote:

Actually, I'm not sure why we drain the glycerine at all. I'm not convinced it wouldn't work even better to leave the glycerine in the solution at Stage 2.

The reason we remove the glycerine is that it pushes the equilibrium to the right. This is why we get high conversion with less methanol.

Andrew

Andrew's Post:

quote:

The reason we remove the glycerine is that it pushes the equilibrium to the right. This is why we get high conversion with less methanol.

OK, thanks for clearing that up for me. Now it makes sense.

One way of thinking about the base/base reaction, to explain why it works better than single stage, is to imagine 2/3rds of the methanol and caustic of a single stage being used in the first stage. This will obviously starve the reaction of reagent so reaction will be incomplete.

Then think about the two choices below:

(a) Add the remaining 1/3rd. Stir and settle.

(b) Drain the glycerol then add the 1/3rd, stir and settle.

In case (a) you will have, in effect, a single stage reaction and the usual conversion.
The added reagent will be distributed between the upper and lower layers. We know that about 2/3rds of the methanol will go into the lower layer.

In case (b) there is no lower layer to grab methanol so it will be available in much higher concentration. We see that in this case we will be adding far more methanol than needed.

quote:

In case (b) there is no lower layer to grab methanol so it will be available in much higher concentration. We see that in this case we will be adding far more methanol than needed.

That makes it very clear. Thanks neutral.

I think the short answer to your question is this: Once it is up to temperature you can follow neutral's numbers exactly.

These are the goals:
1. Polish the oil so you've got a good start.
2. Get it up to temperature (might be fast, might be slow.)
3. Follow neutral's numbers.
I think you'll get good results every time.

For mixing I use the 50 gpm sprinkler pump.[/QUOTE]
Bio-LOGIC, thanks for your contributions in pioneering process improvement with innovation on a big scale. I am intrigued by the "polish" process that you use to remove water and debris from the WVO process as a first step. I too struggle with wet oil which is at least partially hydrogenated(which has uncertain effect on outcome). I have been using aqueous 50% NaOH but struggling with the water that this brings to the process. I am wondering if mixing the glycerol with the catalyst to remove the H2O in the catalyst and the WVO as an initial step would make the result more predictable with a lower water content to begin the stage 1 reaction? Perhaps Neutral could comment on this as his comments have contributed immensely to this very interesting and informative thread.
Best regards, jackmac

Jackmac,
You mean you've been using NaOH in an aqueous soultion? Or you've been using the concentrated aqueous method? If you are using liquid NaOH, there is your biggest problem. That is WAY too much water! The conc. aqueous method adds a little water too, but not that much. Get NaOH crystal and try that. Keep as much water out as possible. HTH

neutral,

why do you prefer this explanation:

quote:

Then think about the two choices below:

(a) Add the remaining 1/3rd. Stir and settle.

(b) Drain the glycerol then add the 1/3rd, stir and settle.

In case (a) you will have, in effect, a single stage reaction and the usual conversion.
The added reagent will be distributed between the upper and lower layers. We know that about 2/3rds of the methanol will go into the lower layer.

In case (b) there is no lower layer to grab methanol so it will be available in much higher concentration. We see that in this case we will be adding far more methanol than needed.

Over the idea that retracting the glycerine moves the equilibrium? I have spoken to several qualified chemists and chemical engineers who all think retracting is why it improves the result.

Andrew

quote:

Originally posted by Joe_M:
Jackmac,
You mean you've been using NaOH in an aqueous soultion? Or you've been using the concentrated aqueous method? If you are using liquid NaOH, there is your biggest problem. That is WAY too much water! The conc. aqueous method adds a little water too, but not that much. Get NaOH crystal and try that. Keep as much water out as possible. HTH

Joe, thanks for the advise. After struggling with the poor results, I have finally tried the flake naoh and the results were much better, even the titration has been significantly impacted using dry vs 50% water. I have a couple of pulsafeeder metering pumps that I would like to use for dosing and insuring that the methoxide is adequately mixed with the wvo, which lends itself to a solution vs a dry measure, if that can be made to work as bio logic and johno have done.
best regards, jack