Was doing a little math while i was bored at work last night and just wanted to double check my numbers. Assuming a recipe of 5 gallons methanol, 3 lbs KoH for a 25 gallon batch, you are recovering 40% of your methanol from every batch and you're using fabs ratio of 1% magnesol by weight, 7.2lbs per gallon. A 55 gallon drum of methanol, 52lbs of KoH, and 31lbs of magnesol, would net you approx. 430 gallons of BD. Is this correct or am I off base here?

 

Your recipie formula is off.

3lbs of KOH into 25 gallons of methanol may, or may not be enough to make quality biodiesel.

You should not follow that formula as there is a VERY good chance you could damage your engines fuel system.

The ABSOLUTE minimum KOH required to barely scrape into astm standards is 7 grams per liter KOH (adjusted for purity)
Most people get KOH at 90% purity so you would have to adjust for this .. 7 divided by .9 means you need 7.8 grams of KOH minimum.

Remember, that 7 grams base is the absolute minimum needed.

I hate it when I see people following these backyard recipies for making biodiesel.. Then, when thier injector pumps goes bad, they blame the biodiesel and post their unfortunate experience for all to read..It makes people think biodiesel is bad for your engine or at the very least is a risk when in fact the person didnt make the stuff correctly.

Please do it correctly.

While this forum is a great place for ford trucks, this forum IS NOT the major hangout spot for biodieseler's.. To find correct information, please visit
www.biodiesel.infopop.cc

You can also find PROPER titration instructions here:
http://www.murphysmachines.com/how_to/how_to_titrate.html

 

The way I figured that is started with
55gal methanol = 11 batches at 25 gals per batch = 275 gal of BD. 40% of 55 is
22gal = 4 = 100 22 is
9 = 1 1/2 = 37 1/2 9 is
3.5 = 1/2 = 12 1/2 3 1/2 is
1.5 = 1/4 = 6 1/2
I didn't figure it exactly. just rounded up and down to make it easier but wanted to know if that is how the methanol recovery worked. can you continue to recover until you don't have enough methanol to work with or can you only recover once before you don't have pure enough methanol?

 

I understand that you don't agree with this recipe and you are all for titration and i'll probably titrate if and when i ever get started processing, but was just using that as a base recipe to run numbers with. my main question as i stated in the last post, is about the methanol recovery. Can you make a batch, recover your 2 gallons of methanol, add to it to make another full batch, recover and add to it, or do you make a batch, recover your 2 gallons of methanol and then use that to make a half batch and then not recover off the half batch?

 

I think Fabman will probably know more about the in's and out's of methanol recovery than I do..

However, here is some food for thought.

Why bother even recovering the methanol? It is energy intensive and the returns are minimal..

A better way is to dump your glycerin into the raw used oil for the next batch.. Mix them up real good and any left over catalyst and methanol will be used up by the oil. This can lower your titration values for the next batch, it requires almost no energy and since all the remaining excess in the glyerin will be used up, there's really no waste.

This still leaves the issue of the small amount of methanol left in the biodiesel itself.. The amount is very small.. is it worth it to recover? I'm not so sure since all of the meth and catalyst has already been recovered in the glycerin by the next raw oil batch.

It has also been reported that this technique lowers the gel point of the fuel but these results have not yet been verified in a controlled situation.

It can lower the amout of FFA's in the next batch however.. This has been verified.

 

Your formula of 25 gal WVO 3lbs KOH and 5gal of Methanol is a very good formula that I believe Fabman came up with and I have been using for a long time. Calculation of KOH at a minimum of 8grams per liter comes to 757 grams of KOH. 3 lbs of KOH converted to grams comes to 1360.8 grams, about 42% more than the 8 gram per litre minimum. With this recipe Titration is basically a waste of time if the WVO you use always comes from the same supplier. If you titrate, you can calculate the exact amount of KOH needed which will be alot less than 3 lbs. As I stated before, for the little extra cost of KOH, it is not worth the hassle for me to titrate.

 

8 grams per liter is the MINIMUM for new UNUSED and FRESH oil. Waste veg oil will require the Base amount of 8 grams per liter + whatever the titration amount is.

If his oil titrates higher than around 4, his fuel will be substandard.

The average titration in my area (350+ restaurants surveyed) is about 5 or 6 depending on the time of year.

Titration is a lot cheaper than an injector pump.

 

Murph,
Does mixing in the old glycerol with the new oil also lower the amount of methanol used to make the next batch, if so by how much?

 

The technique is basically making biodiesel by using the excess chemicals left over in the glycerin.

Part of your waste vegetable oil will be well on its way to becoming biodiesel..

So basically, your 100% waste veg oil starts to become 95% waste oil with 5% biodiesel mixed in (in laymans terms).. When you throw that into the reactor, since some of it is already biodiesel, you require less everything to convert the rest of it.

The numbers I quoted all above are for example only and I have no exact figures to give you.. But, it has been confirmed that it will lower your titration levesl and require less chemicals for the next batch.

 

What I was wondering was how much methanol you save with that process. The lye I'm not worried about with the oil I get I only use on the average 680g for a 40gal batch. Since I get my oil from the same place it doesn't flucuate much at all on the titrate. The lye is cheap in the big scheme of things, I'm looking for a way to cut the methanol cost that's where you can save money.

 

Energy intensive? I don't think so. When I was using vacuum to recover my methanol I was using a Gast Vacuum pump with a 1/4 hp electric motor. Since 1 hp= 750 watts, I was using 187.5 watts PER HOUR. My electric costs are 6 CENTS PER 1,000 WATTS. I could process 50 gallons of glycerol in less than 3 hours at a cost of approx 3 1/2 cents!

Even though I buy my Methanol 600 gallons at a time [2- 300 gallon totes] at wholesale cost, [ just bought 2 yesterday, $.32/pound] by recovering the methanol I save almost HALF of my raw methanol costs................

Most people don't use as much Methanol as I do, but pay more than I do, so the savings will be more for somebody that pays a higher price per pound.

 

Most 1/4 HP motors use way more than 187.5 watts. I know the math works that way but in motor design economic reality, a 1/4 HP motor will usually pull around 500 watts or more. But that's a minor thing really the way you are running your numbers. The difference in cost between 200 and 500 watts is hardly worth discussing.

What about heat? Don't you have to raise the temp some? There has to be more operating there than just a vacuum pump.. yes??

In either case, I don't think it would matter even if you had a heating element and pump working.. I didnt realize you could recover the methanol so fast.. I was under the impression this was an all morning and all day thing.. You must have a huge column.. How big is your condenser? what about purification? Even a really good condensor wont make high purity methanol.. Dont you need a molecular seieve or something? Or at least some other media to remove the last amounts of water?

This brings up another issue.. How much did it cost to set up that recovery system? Would it not be cheaper to just use up your excess chemicals by pre-reacting your waste oil?

 

SUIT AND TIE

 

All my tanks are insulated, to minimize heat loss. I do have heating eliments on each tank, but they seldom come on. If you control the amount of vacuum [keep it lower than 20"] you'll get almost no water. water needs about 25" to vaporize.

Cost? almost nothing, I farm 2,800 acres now and have a large "boneyard" to pick from. If I were to mix my glycerol back into the "new" oil I'd have to double the size of my tankage.

I no longer use vacuum............I use a new system that strips the methanol faster [ about 15-20 gallons per minuit] and uses even LESS energy.

 

what type of system are you using now fabman and how complicated and expensive was it to put together? if and when i ever get around to building a processor, i'd only be looking at running two 25 gallon batches a week 3 at the max. with using only about 40 gallons of methanol a month would it be cost effective for me to worry about methanol recovery? i think that since it would be over an hour drive for me one way to get the methanol (closest i've located so far is in the st louis area) recovering it would pay for itself in a short period of time just by extending the interval between going to get meth, fuel, and drive time to go get it. what i've read so far it does't seem too cost or labor intesive to add a vacuum pump and condeser using an old hot water heater as a vessel. but i'm very interested in hearing everyone's thoughts. Thanks to everyone for their input so far.