I just added a reflux column to my 15 gallon still and if my calculations are correct (based on weight of samples), I'm getting anywhere from 85 to 92% purity methanol. (I've got pics if anyone wants to see my urban-fabulous still).

Anyway...If we assume that the residual percentage of the reclaimed methanol is indeed water, then I'd potentially be putting water back into my bio process, right?

Are there any guidelines / speculation / experience on how much reclaimed you can use without causing problems?

How do I determine what an acceptable "overall" purity would be if I use, say 30% reclaimed of 86% purity?

In my case , 30% reclaimed would be just over 7 liters of methanol...of which almost 800 ml would be water. Yikes! Don't want that in the process...I spend all that time dewatering my oil, after all.

Anyone have any advice? Does it matter?

the extra water will make more soap depending on the initial quality of oil. the better the oil the less soap.

lower the temp at the top of your reflux column and you can improve the purity. it might take longer, the down side.

-dkenny

ps I usually pull 98%+ purity with or without prewash.

Thanks for the advice... Right now, the process is pretty slow. It takes me around 9 hours to distill 13-14 gallons or so of pre-wash glycerin to end up with just over 3 gallons of methanol. Does that sound normal?

How do I go about lowering the temp at the top of the column?

Pot temp stays around 150 (except at the end) and head temp is around 156-157 or so. I shut it off when the pot temp creeps up to around 165 or so.

The column itself is 2" in diameter and around 20 inches long and filled with stainless pot scrubbers. I couldn't find any formulas for estimating how much column I should put on the still...Perhaps I need a taller column.

The heat for my arrangement comes from two 3500W (rated at 208v) electric elements run at 110 (should be around 875W run like this)

They're wired separately, so I unplug one of them just as the pot comes up to temp.

I've heard people say you can use a router speed control box to vary the heat going into the still during distillation. Would that help? The 15 amp units would be plenty to control just one element...

I run my pot temp until the temp is around 200F.
it does sound like your getting all the methanol out. time wise sound about right. you might try injecting air into the pot. a small amount of air flow. but keep a close watch on the head temp.

I just use a PID to control the head temp.

my column is 5 feet tall. otherwise its made just like yours.

I found that I needed more heat than a 4500W/240 element running on 120v. I'm also distilling from 55 gallons of glycerin.

otherwise sound like your on your way, just needs some tuning.

-dkenny