without scrutinizing the numbers something not adding up...

this past weekend I help get someone started on making Bd in there new system. being a local 'expert' on making BD I was happy to help.
we heated the oil and mixed in the proper methanol/KOH mix for single stage.. after 1.5 hrs the batch still failed the 27/3 test. at this point I said...wait let's make this a base/base reaction or 2 stage. We did this.. at 45 minutes into the 2nd stage to passed the 27/3 test. I stopped adding BD at 9mls into 27 mls of methanol..blew away the test...but just to show some others that came later after all this was done I added a couple of drops of WVO to this mix.. fall out happend right away... so does the WVO draw methanol into it...I don't think so..if it did that would imply the vege oil and methanol mix..and we know they don't

-dkenny

When you added the WVO to your 27/3 test vessel, there was no catalyst mixed in with the methanol therefore the immediate dropout of oil.

When you add glycerol to your WVO both the catalyst and the methanol are present for a partial reaction.

Is anybody still trying 5%wash water glycerin treatment? I've been doing it, and had no idea this thread and discussion existed.

My first couple of batches went ok, but around the third and 4th batch I encountered a ton of FOAM following methanol recovery from the finished BD. I use a centrifuge to spin out soaps and any residual glycerin. I had foam coming out of the the tank and spilling onto the garage floor.

I have assumed that this is excess soap in water. I could be wrong, it could be excess soap being carried in methanol I guess. I use vacuum recovery to remove the methanol, but there is always some still left which I drive off by spray circulating in an open top tank. Lately I have been rushing that step and running the centrifuge at the same time. Its possible that with some methanol still in the batch, the centrifuge agitation was making suds from soaps.

I've done 2 things to stop the foaming soaps, but have not isolated which one is working yet. I have reduced my catalyst. I use NaOH. I used to titrate at 1-1.5 so would use 6-6.5 g/l. I've now dropped it to 3.8-4 g/l. I am using about 15 gallons of glycerin to treat 55 gallons of WVO (which is brite and clear with trace water to start). The other thing I have started doing is to distill/dewater after settling and draining the glycerin pretreatment overnight. If my WVO is picking up water, this step takes it back out prior to reacting. I guess it would also remove the methanol picked up during the glycerin pretreatment though.

Anybody else still working with this method?

Jon,

I have never tried the glycerol pretreatment of WVO with water added to the glycerol. It seems to me that you should use the driest glycerol that you have, so that it can suck up any resididual water in the WVO during the pretreatment thus giving you a drier product to convert to BD.

I am sure there is an amount of moisture in the pretreatment phase that will work, just not something I would want to try to figure out.

Ok, I need to read things a little more clearly. I read on and forum they were talking about this and I did what they were talking about. I had 30 gals of oil, heated it to 130 degrees and mixed in 1.5 gals of water free glyc. It has mixed now for an hour and I am about to turn it off.
? What now.

quote:

? What now.

Give it time to settle, drain the glycerin (might be a greater volume than you put in), re-titrate, and if you are happy with the new titration, proceed as normal.

The glyc that settled to the bottom will not run out of the tank. Nice clean oil on top now though, but I'm stuck on how to get it out.

hiper,

I let my oil settle in an open barrel outside my shop. The resulting glycerine can get a bit thick. If it gets too thick to run out, I have run a tube up through the exit valve to clear a path for the liquid to flow. Most of the liquid that exits will be oil. Once the oil has drained, I can then scoop out the glycerine.

In my experience with this process, the more you do it the less thick the resulting glycerine gets. I think that has to do with reducing the amount of catalyst in the subsequent batches.

This is interesting.

So if i understand it correctly the idea is this?
Using 5% prewash glyc will contain more methanol and catalyst because its drawn out more from the last batch of bio with the wash
The WVO will get some water in it too then.
But dewatering the WVO with a condensor after that should remove any water?

Pat,

I am not sure what you are asking here.

If you use the glycerin from the previous batch of BD and do not do a 5% prewash on the previous batch, then you can use the glycerin from the previous batch to pretreat the subsequent batch.

The results for the subsequent batch are:

1) Reduce the titration number for final processing.

2) Perhaps reduce the amount of methanol needed for final processing.

3) Reduce the amount of water in the WVO and therefore reduce the amount of soap created.

4) Perhaps reduce the amount of methanol left in the glycerin, so that it can be further processed more easily.

5) Reduce the amount of catalyst needed for the reaction.

I think those are the benefits.

The down side is that it takes longer to process a batch and it is much more work. The resulting glycerin is much thicker and can clog your lines.

Hi Eurocab,

I use the glyc pretreatment already so i see the benefits you mention.

What i was wondering is if doing a WVO/glyc pretreatment with glyc that has water from the 5% bio prewash will be anymore effective. The reason being is that the 5% water now in the glyc will contain more methanol & catalyst from the bio prewash, and thus giving more chemicals to the part reation of the WVO.
Dunno, maybe too small to notice. Or the water may actually hinder the reaction?

quote:

5% water now in the glyc will contain more methanol & catalyst

While this is likely true, I think the water will be far less likely to give them up to the oil than what the glycerin would give up of the smaller quantities w/o the water.

And then any water that makes it to the WVO does hinder the reaction by consuming the KOH or NaOH and making soap.

I agree. I think water is the enemy. Even if you get some additional methanol from the BD, which is a very small amount, you still have to deal with the water/soap creation, which you want to limit or avoid.

Ryan,

I agree with Eurocab. Water is the enemy. Adding 5% water in the previous batch does a great job at reducing methanol, catalyst, and soap from the previous batch, but I'd steer clear of it if using it to pretreat the next batch.

However, it would be nice to see what results you get relative to what we've been getting.

I was doing a LOT of work on this back in April, but I was in the middle of a work related project that kept me from getting firm numbers on how much material was transferred during the pretreatment process. I may actually have time to do this over the next month.

Do any of you do methanol recovery? If so, here is yet a BETTER WAY TO PRETREAT AND PREWASH, and only takes a couple more steps to do so....

If doing methanol recovery in a separate vessel, on glycerine biproduct by itself, once finished demething, NEUTRALIZE the KOH out of the glycerine by adding 31+ % HCL (pool acid). Do it while hot (but less than 200 degrees F to prevent flashing) and let settle overnight. When you drain this stuff in the morning, about 1/2 the tank will be honey colored CLEAR glycerine.

Use this clear glycerine IN PLACE OF the glycerine in your processor when you're ready to prewash.

Steps, for clarity:

1. Pretreat with glycerine biproduct from previous batch.

2. Drain pretreatment off, and hold for methanol recovery.

3. Process oil.

4. When processing complete, stop, settle for 30 minutes, drain glycerine biproduct and hold it as pretreatment for next batch.

5. Prewash with CLEAR neutralized glycerine with 5% water. I'm actually using 10% glyerine and 10% water. Mix for 1 hour, then stop, settle overnight.

For me, when washing, I see HUGE reductions in wash times. Think of the neutralized demethed glycerine as a wrung out sponge. Tossing this and some water into the processor just sucks out the methanol, KOH and soap. My 'typical' wash times are 6 hours, and my own record is 3 hours and 20 minutes, using 2 wash waters 1/2 the volume of the bio for each wash.

If you'd like more detail on the process, post/email and I'd be more than happy to walk you through this.

- Steve

Awesome

Just to clarify, please -

After processing a batch of WVO into bio, you settle, drain off the usual glycerine, then add back the clear glycerine at a rate of 10% plus 10% water. Mix for an hour and settle.

Then drain off the clear glycerine (which will contain methanol, soap, water)

What do you then do with the clear glycerine you drained off?

Also, at the beginning of the next batch you pretreat the WVO with the usual glycerine from the previous batch. Then send that glycerine to methanol recovery.

Correct?

Paulus,

That sounds right. He is taking this procedure an additional step to shorten the wash time. Sounds like an interesting idea. I bet it would cut the settling time for drywashing as well.

Paulus,

You're right on with your response. I didn't provide quite enough detail on the first response, as I didn't know if anyone cared to hear/read it.

Actually, instead of adding a 10%/10% mix, I add 7 liters of water initially, to aid in stopping the reaction, and hopefully keep from reaction reversal (Andrew's suggestion). I add this over a couple minutes, as I've seen 'snow' on my secondary tap when adding too quickly.

Immediately after adding the water, I chase it with a mixture of 13 liters of glycerine and an additional 5 liters of water. Since the neutralized glycerine has a little water in it due to the neutralization process (the HCL is only 31% pure), I only add 12 liters of water instead of 13. (My bio is about 130 liters after draining off the initial glycerine biproduct.

quote:

What do you then do with the clear glycerine you drained off?

I'm working on that. Currently, I'm tossing it. I just started running some numbers on the amount of acid necessary to neutralize this glycerine for re-use. I'm thinking that I could probably use 50% reprocessed glycerine and 50% virgin. This should allow me to stockpile neutralized demethed glycerine so that others can use this material as well. Currently, the numbers were chosen so that I would always have enough glycerine (barely) for the prewashing stage.

Washing is really a breeze....I'm washing right now, on my second wash water. - I started 70 minutes ago and should be done in 2-3 hours more.

- Steve

Eurocab,

quote:

I bet it would cut the settling time for drywashing as well.

Drywashing? Please explain.

Steve

Soap in bio only stays in solution because methanol is present. Remove the methanol and the soap falls out. The technique of removing soap this way is called drywashing.

Awesome what you're suggesting is a good idea. It must speed up washing considerably.

Awesome,

quote:

Drywashing? Please explain.

What Paulus said.

With less soap to dropout, less settling time for drywashing.