I'm considering reworking my still into something physically smaller then I have now (It's a hodgepodge of stuff when I started this and it's time for a rework!). While at it I'm considering adding a reflux column to the still to increase my recovery.

I've been reading all the threads on the relux columns, and I have a question about them that confuses me:

My current still uses a simple small radiator setup with a mist of water blowing from a fan over the condensor. From the pot we insulate the line running to the radiator so that it doesn't condense and run back into the pot. I got that part

With the reflux though, I don't see insulation at all on the column. My question is that with a very tall column (such as fabricators 5 footer), what keeps the entire column from cooling and having all the vapor condense back into the pot?

Is it a matter of applying that much more heat to make up for losses? I currently have (3) heater elements in the bottom of my 55 gallon drum pot, wired in series running from a 220 outlet. Takes about 4 hrs to heat 45 gallons to actually see any condensing output. I run this outside while I'm here at my shop, so I'm wondering with the wind blowing around the column, what the affect will be? Jim

quote:

With the reflux though, I don't see insulation at all on the column. My question is that with a very tall column (such as fabricators 5 footer), what keeps the entire column from cooling and having all the vapor condense back into the pot?....... Is it a matter of applying that much more heat to make up for losses?

The idea with refluxing is to use the same amount of heat (or nearly) at the pot, but collect less methanol per minute (but purer) from the top of the column, due to the constant condensing and redistilling in the packing material. This only happens if there's a steady drop of temperature as the vapors rise through the column, which is why you don't want to insulate the column.

Often the problem is that even with good packing material, the vapors actually get through the column TOO quickly, which is why many columns have a cooling coil at the top and a splitter, so you can return even more liquid back down the column.

There's a good discussion of reflux at homedistiller.org

quote:

Originally posted by Jim R:
. . .
While at it I'm considering adding a reflux column to the still to increase my recovery.
. . . .

A reflux column will not increase recovery. A reflux column may actually reduce recovery volume.

A reflux column will increase the purity of the recovered methanol.

[/QUOTE]

A reflux column will not increase recovery. A reflux column may actually reduce recovery volume.

A reflux column will increase the purity of the recovered methanol.[/QUOTE]

Understood, I guess should have explained more fully what I meant by increasing recovery quantity:

It seems reading through the posts, that most are recovering between 20% to 30% of the volume that put in there still. I am nowhere near that - granted the amount of methanol used in the process may be higher in some else's equipment, therefore the amount recovered will be higher also.

I seem to achieve only in the neighborhood of 11-12%. I have a feeling that shortening up line from the still head to the condensor will help a bit, perhaps flooding the condensor in a bath of recirculating water will help too (instead of misting nozzles spraying).

I have a batch running right now, started at 7:45 am this morning (now almost 6 pm) and have recovered 5.5 gallons out of the 44 gallons I started with.

I process with a Biopro 190, my total input methanol is 20% (10 gallons methanol to 50 gallons oil). Jim

what are you running you pot temps upto?

you might not be getting all the methanol out.

-dkenny

quote:

Originally posted by dkenny:
what are you running you pot temps upto?

you might not be getting all the methanol out.

-dkenny

First off I don't have a way of measuring the line temp right where it enters the condensor - next rev I'll take care of that. Pot has two temps gauges, 1 low above the elements and 1 high at the head. When I shut it down this evening, lower temp was 260 and upper temp was 210. Recovered just a smidge over 6 gallons in 12 hrs start to finish. Jim

for your next rev I would suggest

a reflux column
inject air into the pot
used the temp at the top of the column to control the heating elements in the pot.

if you want to speed up the heating rate unwire one of the element.

another thought? what is the temperature at the bottom of your condensor? it should be cold.
also if the radiator is large enough you don't need to mist water on to it. I use air cooling with just a fan, no water.

-dkenny

And look into a PID, the PID is the most important part of my still.

I just built a reflux column, 3 foot of tail pipe welded to a pipe nipple the size of the bung of a 55 gallon drum, 5000w element in lower part of drum, pid controller set at 156 degrees F, thermal couple in top of column. three solid days of running this set up produced 12 + gallons of methanol of 88 to 90% pure. column filled with marbles. I thought I should get much higher purity and same quanity in 24 hours, not 72 hours. Any ideas would be helpful because I'm in the same boat with Jim R, don't understand this process, but would like to get it right.

I believe you need higher temps, up to 260F if you plan to use the glycerin to make soap.

quote:

Originally posted by dkenny:
for your next rev I would suggest

a reflux column
inject air into the pot
used the temp at the top of the column to control the heating elements in the pot.

if you want to speed up the heating rate unwire one of the element.

another thought? what is the temperature at the bottom of your condensor? it should be cold.
also if the radiator is large enough you don't need to mist water on to it. I use air cooling with just a fan, no water.

-dkenny

The radiator is warm only at the top, right where the 'line in' enters. I monitor the mist spraying at the radiator and adjust the water mist flow as the temp increases. Jim

quote:

Originally posted by fabricator:
And look into a PID, the PID is the most important part of my still.

Agreed, that's first on the rev list. How does your pid 'know' when the process is done, in order to shut it down?

It doesnt, it will keep raising the pot temp to hold the set point, a previous poster mentioned 260 degrees, that is WAY to high, I usually shut my still down when the pot temp is somewhere around 190-200.

for pids looking into getting a 2 output pid. I recently had to buy 2 more pid to run my processor. the one i got, watlow 935, have dual outputs. I'm going to use the 2nd output as a latching alarm. this will be normally closed.

some details.
pid 1 - monitors the pot temp, but doens't control heating during recovery
pid 2 - monitors and controls the head temp during recovery.

I will use pid1 2nd output to control the alarm. this will drive a mechanical relay. the relay will be close until the alarm condition happens. this happens at 200F(pot temp). then it latches open. the contacts of the relay are in series with the SSR control lines. open will mean no heat. the whole process stops.

as a side note if you're using a pump to stir the pot make sure the seal can handle the temps involved. the HF/NT pumps don't like much over 200F.

pappa,
do you inject air into the pot? this helps reduce the recovery time.
for higher purity reduce the 156F to 152F..I know this doesn't seem like much but it does make a difference. also make sure the pid it programmed to hold to +-1F of the set temp.


-dkenny

dkenny

That is about the idea I was having on PID's except I was thinking to get be able to use the cheapies you can find would have to use 2 seperate PID's. I know there are some with all sorts of options but also know the more options the more $$$$.

Trc

its all a matter of looking long enough I thin I paid $20 for both of the watlow 935's that i currently use.

if you can only find single output pid its still possible. you might loose the auto shutdown..of course you might be able to configure 3 pid to provide this functionality. it just depends on the pids.

ideally you'll want pid that'll drive SSR's not mechanical relays. but if you can find the mechanical relay outputs then use those but expect a longer cycle time. I ran my methanol recovery setup for a long time using 5V relays to switch 24v to drive the HVAC relays. it worked fine. not the safest setup..relay's arc


-dkenny

Please explain what a PID is and how it is used. I am ready to start building methanol recovery still.

quote:

Originally posted by freesoul:
Please explain what a PID is and how it is used. I am ready to start building methanol recovery still.

PID Controller

The PID controllers that they are talking about in this thread control the cycle time of the heating element according to the temperature set.

gotcha, how do you connect it to monitor temperature at the pot and head?

Still looking for info. We started to put our recovery unit together last night, and according to my partner it is cranking up its first batch now. We are incorporating almost a 4' reflux column. Head temperature measurement from the small bung on the top of the drum, and pot temp inline with the pump. Here are a few pics, I'll post more later.

http://picasaweb.google.com/fastbiker/MethanolRecovery#