Attached in this and the next post are photos of my 30 gallon water heater. Obviously I will plumb the drain and pump suction to the bottom hole where the drain valve used to be. I'll valve it so that the pump can suck in from where ever and can be used to pump out the contents to where ever. Lots of valves and Tees.

Should the discharge be into the top to maximize the movement of the glycerin in the tank to keep the element from burning out? Can I go in from where the pressure relief used to be on the side so that it splashes all over the place and maximizes the surface are of the droplets? I'm going to run the 4500W element at 110V so that it puts out 1125W.

-Jim

Drain_and_PR_holes.JPG (28 KB, 89 downloads) Side of Tank

The reflux column will obviously go up from either the hot or the cold taps on top. I've removed the cold water sleeve.

The other port will have a steel line going to the bottom of the tank so that I can pump air/vapor from the top of the methanol collection tank into the bottom of the still. This should speed recovery, from what I have read. I'm going to Tee the pipe and run a line directly outside so that there is a safe path for the system to burp if I ever screw up and turn it into a pressure vessel on accident. This line will either have a pressure releif valve on it or a check valve to make sure the air from the pump goes to the bottom of the tank.

-Jim

Tank_Top.JPG (113 KB, 49 downloads) Tank Top

Jim.

Having spent 3 hours just last night reclaiming methanol from my latest batch of biodiesel, I would concur that you want as much movement and splashing as possible. I was experimenting last night and the rate of methanol coming out of my still reduces drastically when the pump is off; amazing.

I pump air into the top of it; just enough to help carry the vapors over to the condensor. Somehow, this helps drastically, too. I think my methanol may be condensing and running back into my hot water heater if the air is off. Weird.

I've read that the air is more effective if it goes in at the bottom of the tank. Mcgyver does not use a pump anymore. He just pumps air in at the bottom.

My question is: Do I need the pump return to shoot straight down into the glycerin to make sure the element does not burn up or will there be enough flow just caused by the flow of glycerin down to the pump suction.

-Jim

Hi Jim,
I think with your element running at 1/4 power (110V), the chance to burn it out will be really small.
The conventional heating elements are designed for a power density of abt. 5W/cm² at 230V supply, with 110V the element should not reach the temperatur for a burnout if immersed in the glycerol.

good luck

Dieter

Well, it's too late now. I plumbed it in from above. There will still be lots of splashing. It will just be splashing from the return spray going down into the tank liquid instead of it spraying against the side of the tank.

The only other design option that I have right now is where to discharge the air at. I have the option of setting at what height the air gets discharged. I can even have it go into the returning glycerin before it goes back in to the water heater.

See the attached photo. The Tee on top with the bore-thru swagelok fitting on it allows me to set the height of the 3/8 OD air line at anywhere from right in the Tee to at the bottom of the tank. The only problem is that I will have to use multiple lengths of tubing with multiple ferrules and nuts. The ferrules can't easily be removed once they are swaged into place.

-Jim

Tee_for_pump_return_and_air_return.JPG (25 KB, 64 downloads)

Photo of the piping from the suction at the bottom of the tank to the circulator.

-Jim

Still_lower_piping.JPG (40 KB, 58 downloads)

Photo from the pump to the temperature guage.

-Jim

Still_upper_piping.JPG (37 KB, 53 downloads)

quote:

I've read that the air is more effective if it goes in at the bottom of the tank. Mcgyver does not use a pump anymore. He just pumps air in at the bottom.

Hmmm... bubbling air in from underneath, eh? I wonder if I could just add a fish tank bubbler at the bottom of my still in a spare port. Would that be enough to help?

I don't have a pump on my still right now and I don't normally stir / agitate it at all during runs.

If I use prewash, would the air liberate more of the water or not? Perhaps that's more of a function of the temp...

It would definately be more than you are doing now!

The only problem with just adding a fish tank bubbler would be making sure that your collection jug was vented outside. You would be constantly forcing extra air into it and would surely push some methanol vapor out into the people space if it was not vented outside.

My plan is to use a metering pump to suck air from the collection jug and push it into the still. I suppose it would be just as easy for me to add a venturi after the pump and pull air in using the pump flow, ala GL1 Ecosystem processor.

-Jim

Bore through swagelok fitting in Tee on top of still.

Swagelok_fitting.JPG (15 KB, 47 downloads) Fitting in Tee

Swagelok fitting with 3 feet of tubing installed. All but a few inches of it is in the tank. It sits just an inch or so off of the bottom of the tank.

-Jim

Swagelok_fitting_with_tube.JPG (27 KB, 42 downloads) With Tube

quote:

Originally posted by Jim D:
It would definately be more than you are doing now!

The only problem with just adding a fish tank bubbler would be making sure that your collection jug was vented outside. You would be constantly forcing extra air into it and would surely push some methanol vapor out into the people space if it was not vented outside.

My plan is to use a metering pump to suck air from the collection jug and push it into the still. I suppose it would be just as easy for me to add a venturi after the pump and pull air in using the pump flow, ala GL1 Ecosystem processor.

-Jim

Ah ha! A metering pump. Tell me more.....I've been trying to figure out how to circulate the air from the collection jug back into the processor with little success.

I have 3. I can only find 2. The two that I found are tubing pumps, aka peristalic (sp?) pumps. One pumps up to 60 gallons per DAY. The other one pumps up to 7 gallons per DAY. The pump I am missing is a diaphragm pump. It pumps up to 380 gallons per DAY. I'm not sure which one to use. The 7GPD seems WAY too low. The 380GPD may be too high. It can be turned down to 190GPD, but is that too high. How much air flow do I need?

The Diaphragm pump is this one:
http://cgi.ebay.com/GRI-15926-001-Bellows-Metering-Pump...eZWD1VQQcmdZViewItem
They have been running this auction for a year now. I bought mine 6 months ago or so. No problems on the transaction.

http://www.gripumps.com/ Select bellows metering pump.

-Jim

Jim D

Is that a Taco pump you are using?

Taco 009-F5. A 007 would probably be better, but it should work fine. The 9 has a high lift capability (high head) with lower flow. The 7 is high flow with lower head.

-Jim

I picked up a couple of Bell & Gossetts real cheap on ebay.

I have had good luck with the Harbor Freight pumps, yet I see no reason to ever buy one again when you can get a Taco 007 for around thirty bucks more.

http://www.pexsupply.com/product_dtl.asp?pID=1983&brand=Taco&cID=289

I still wonder why more home brewers are not using recirculating pumps.