The HWH should be insulated well enough for our purposes in July, it may differ in January. You may be correct in looking into more wattage for the heater element. You will need to get the glyc to 210-230 F and hold it there.

Norman

Spence, I'm not sure what you mean by giving it four hours to get hot, mine takes about an hour to get hot then it takes another 12 hours to get to a point where the pot gets to 210f or so, at that point your purity will begin to nose dive, the pot needs to be at least 150 to start and it will need to get progressively hotter as the meth content of the glyc gets lower.

Fab,

I should have stated that there is a temperature plateau that I'm seeing in the reactor. Yes the glycerin is getting up to 150F after about an hour of heating, but doesn't seem to get much hotter than that. I was hoping that running the element for 4 hours before circulation through the venturi would yield more temperature.

I'm still coming back to the conclusion is that I need more heat.

I believe you are right, it sounds like the venturi causes some cooling also, I believe my element is the folded 5500 watt hooked up for 220.

Spencnaz,

I use a 40gal water heater with the plumbers delight and a 5 gallon bucket of water pushed with an aquarium pump. When demething glycerin, I found the process to be very volatile and prone to boiling. When I heat up the glycerin to 155 or so using 220V, I switch to 110V, effectively cutting the power applied from 100% to 25%. This would be a cheap way of stepping down your power applied. Using this approach, I could keep the pot temp more consistent with less on/off cycles. A PID would be ideal here.

Without looking at your setup in person, I would say that your condenser could be underperforming because its not been crimped. The turbulence and wall contact between the vapors and condenser would be significantly different and contribute to a big difference. The vapor circulation pull created by the venturi is also important. I found that tiny adjustments at the valve created a response with the output. Too much circulation too fast, and the vapor won't condense into the liquid phase. Too slow and the collection rate slows down.

For as many times as I recovered methanol from glycerin, I promised myself that I would never do that again. What a pain. When I decided that I wanted to make soap, I boiled of methanol from the glycerin using a turkey fryer. KOH glycerin makes for a difficult process to get to bar soap. NaOH glycerin will get very hard when cooled if the methanol is driven off. Be sure to add in water just to keep it liquid enough to work with while its still hot and runny.

Spence

You're not by any chance turning the element down or off once you get it up to temperature? It's like boiling water...to continue boiling you have to continue heating.

quote:

Originally posted by Spencnaz:
Fab,

I should have stated that there is a temperature plateau that I'm seeing in the reactor. Yes the glycerin is getting up to 150F after about an hour of heating, but doesn't seem to get much hotter than that. I was hoping that running the element for 4 hours before circulation through the venturi would yield more temperature.

I'm still coming back to the conclusion is that I need more heat.

Greetings Spence,
Could the temperature plateau just be because the methanol is not being removed but condensing a falling back into the pot. I'm sure you know that like a pot of boiling water will remain at 212F until the water is gone the same will happen with methanol. Distillation is sort of a self regulating temperature control. Like Fabricator said, as the methanol is removed from the pot, only then will the temperature rise.

quote:

Originally posted by Paulus:
Spence

You're not by any chance turning the element down or off once you get it up to temperature? It's like boiling water...to continue boiling you have to continue heating.

Paul,

No I'm leaving the heating element on whilst circulating with the pump through the venturi to create a vacuum in the condenser.

DoubleD,

I'm wondering if the volume of glycerol (~55 gallons) is what is making the process slow. I wouldn't think so, but the temps measured at the venturi are only showing a max temperature in the range of 155F to just below 160F.

I did have one idea and that is to modify a pipe cleaner to act as a turbulator in the condenser tube. I have yet to try it, as I do have the pipe cleaner available.

Spence,

I would be curious if your element is getting power the entire time that you think it's on. Can you attach an indicator light or volt meter. 220V with a 4500W element should get that really hot to the point of boilover.

Yeah I'm concerned about that as well. The 'brainbox' has a 600V contactor with it's own fuse. There is a rapid boiling sound when the element is turned on for first 30 minutes but after that, I can't hear a thing.

I have the thermostat bypassed, which is the primary reason I keep an eye on it. Before I was using the thermostat, but that maxes out at 150F.

I have a voltmeter from the autoparts store, it should be adequate to measure the voltage. I also have one of those inductive test lights that just show that power is in the circuit.

quote:

Originally posted by StorminNorman:

quote:

Originally posted by bdubet:
My coolig water is contained in a 20 gal plastic barrel. I use low-tox antifreeze in the cooling water. The cooling water does heat up during the process.

My best recovery to date (18 batches)was 4.5 gallons of 98% pure methanol.

I am thinking I need to plumb a radiator in the cooling water line to cool the coolant further. What do you all think?

That is quite low if you are using 20% methanol in your process. If you are sliding by with 15% methanol, you may be getting it all. The 98% purity speaks well for your temperature control, although I think 179 F is high.

Is there a specific reason for the antifreeze? I make a couple big ice cubes out of gallon milk jugs and cool my recirculating water that way. One could also get a few of the big blue cooler blocks from Wally World, that wouldn't effect your antifreeze.

Norman

I use the antifreeze because in the summer the cooling water gets quite warm. I used to use ice blocks but that became a pain and the freezer filled up with food so I could not make the blocks. I am thinking of using an old blower assembly from a heat pump unit (the part inside the house) and running the cooling water through the condenser to help pull heat out of the cooling water/antifreeze mix.
I brew with a Bio Pro 190 so I am in the 20-22% range for the methanol. The BP uses a two stage process and some of the methanol is consumed in the transesterfication stage I think.
I use PID for temp control. I started out circulating the glycerol and had the temp probe in the stream at the bottom of the reactor. I quit circulating and moved the probe to the top port where the top element used to be. My first batch after that I recovered 4.5 gal and the glycerin was fairly thick (KOH process). The next two batches returned to yielding 3-3.5 gal.
I keep the pot temp just below 212°F to keep the purity up.

The oils I use range from low titrating (1.5-3.0) 50%Palm 50% Cottonseed (donuts) to high titrating (4.5-9.0)50%Corn 50%Canola (greek). The thicker glycerin may have been the highly hydrogenated donut stuff.

I can bring the still up to temp fairly quickly and hold it at temp for as long as I wish. As I said earlier the methanol flows when the head temps are in the 156°F-170°F. Once the methanol stops flowing the head temps start dropping.

My next modification is for a PID control of some sort to more accurately control and read what the temperature in the glycerin is.

Update,

I drained out the glycerin for a later attempt at methanol recovery. I then filled up with oil for another batch of fuel.

I cranked up the heat to about 185 degrees no problems with the WVO, now why can't I get that kind of heat with glycerin?

The oil is now so hot from the water removal stage, that I have to let it cool for several hours before I add methoxide (this high heat phase is part of the GL process).

Nice and hot with WVO but with glycerin, the element pooped out. I'm going to check the 600V contactor again for complete function before I do another recovery stage.

Spence,
With gly, if it has methanol in it, the temp will hold at about 165(pot) for awhile, then rise as the methanol evacuates, eventually heating up as much as the element will allow it. I have seen 250-270F from a 4500w running on 220V
The methanol can and does hold the temp down until it starts to leave.
I recovered this weekend. 2 -70G batches of gly. in 10hrs for each batch, I had reached a pot temp of 200, and for a total of 20hrs recovering(2 days, 10 hrs each batch) I had recovered 35 gallons of methanol at 95% purity avg. That is with a 4000w low density running on 220

Spence,
It sounds like the heating element is doing it's thing. If your applying heat and not getting methanol you stand the chance of generating excessive pressure in the vessel. Do you have a pressure gauge mounted to the tank? I'm sure your aware of that though. What is/was your temperature at the head/output to the condenser?

With my setup the element in the pot is controlled by a thermostat at the top of the reflux column, It is set to kick off at 190F +/-. My tank and piping is insulated up to downward slope of the output. Seems to work fine for me.

Mines not a GL though so this very well may be an irrelevent post.

quote:

Originally posted by Spencnaz:
My next modification is for a PID control of some sort to more accurately control and read what the temperature in the glycerin is.

You can get pids ridiculously cheap on ebay, the best place for the thermocouple is the very top of your pot or the top of your reflux column.

spence,

do you allow air into you venturi when you're recovering methanol?

is this closed when heatin WVO.

if both are yes then what's the output temp of you condenser? must be around air temp? no execptions

my air cooled setup, I can easy put my hand on the bottom of the unit but not the top.. and the bottom feels cool to the touch. the top is around 140F and will give a burn.

yes I have a temp loss between the top of my reflux column and the top of my condensor..its about 10 of 3/8" copper pipe..but this good..after the top of the column I want to cool the vapors.

-dkenny

quote:

Originally posted by fabricator:

quote:

Originally posted by Spencnaz:
My next modification is for a PID control of some sort to more accurately control and read what the temperature in the glycerin is.

You can get pids ridiculously cheap on ebay, the best place for the thermocouple is the very top of your pot or the top of your reflux column.

Yes, I know. I'm going to use it for oil temperature control.

spencenaz,

for distillation, I just use the pid to control the temp at the top of my reflux column and another to monitor the temp in the 'pot'.

I it setup up this to maintain the purity level.

-dkenny

dkenny is right on the mark. Keep the temp between 150 and 155 degress at the top of a properly packed and functioning reflux column and you will get very high purity saturated vapor. I have a fairly inexpensive ($75) controller that I sourced for my system, but it is 110 volt in and out. It could be used to power a relay on and off in a 220 Volt system. I use a 240 volt element to get up to temp and a 110 volt silicone belt to maintain.

Norman