Demething Bio
 

Anyone on here use the dry washing method and demeth the bd first? Im in the process of switching from water washing to dry wash and need to build a setup to safely demeth the bd. Im slightly nervous about building my own and having an accidental explosion, so I'm looking for some tried and tested designs.

Good to see someone "new" posting. I used a "GL EcoProcessor" design (basically a modified Appleseed design). It does work good for recovering Methanol. I need to build a more efficient condenser this summer. I've made about 1200 gallons so far and have managed not to blow myself up yet...

Ive checked out the GL EcoProcessor design before. I just need to figure out how to heat the bd up enough. Sounds like 120V water heater elements do the trick as long as you dont expose them to air or stop circulating.

That is the big explosion hazard, exposed elements in a methanol atmosphere. Always make sure the elements are submerged. As far as heating it up, the "tit" on the thermostat only alows for heating to 140 if I remember right. By removing it, you can turn the thermostat higher. I run ours around 180-185 with the venturi open. Once you get past about 175, it really starts to boil off fast. Ours is wired 220, which helps it heat up faster too.

Would biodiesel sitting around an element, or not being circulated, be a cause for explosion? That would be my only concern. Obviously I can wire it up so they run together, but I'm just looking at worst case scenario.

You would think only if air bubbles were present on the element? Need Fabman or one of the Bio Gurus to chime in on this one I think. We do keep several Fire Extinguishers on hand just in case, and I hang around while running the heating element...

We insulated a 250 gallon galvanized aluminum (or something rather) tank and welding two heating elements in the bottom. Thats being used as our oil heater now, might just re-plumb the setup so it can be used for both. Or even try to do "whole batch demething" while everything is in there.

I think that was Fabman's idea too, welding the element to the bottom of the tank, eliminating the direct contact with the bio. As far as whole batch demething, will that have some reverse reaction?
I drain off the Glycerol, then distill the methanol off the bio. The Glycerol is then used to pretreat the next batch of oil, lowering the titration and the ammount of methanol needed for the next batch.

I read about it on another forum. Supposedly they claim it's ok to do, I just don't know if it's really worth it anyways. Just something to think about I guess.

Welcome to the bio forum! I DO NOT recommend using submerged heating elements PERIOD!


I changed my process years ago to "stove top" elements UNDER the heating tank. I use a flat bottom tank with stove top elements bolted to the bottom of the tank, and insulated to the bottom. 0 chance of fire or explosion.

I use the same system for Methanol recovery. Much safer, and if an element burns out I don't have to remove the contents from the tank to change the element!

I'm in the process of building a whole new processor and will post pics when it's finished, but it may be a while because I'm still finishing up my new shop. I don't need to make any bio in the winter because I stockpiled bio from last summer.

What convinced me was a test I did with a 10 gallon glass container. When I saw bubbles forming around the red hot element I decided that maybe this wasn't such a good idea.......

Hi Don, glad you joined in. Hope all is well. What do think about a partial reverse reaction with a whole batch demething?

Morning Trent. I've heard bad things about whole batch demething, but haven't tried it. Why ask for problems...........

All is great here, just trying to finish our new house and shop. I'm putting in more hours/day since I retired than when I was working for a living.............lol

I think your not alone there, my Father-in-law says the same thing!

Yep, but at least I can pick the things I want to do!

I like your "stove top" method better. I just don't like the idea of a red hot element surrounded by fuel. Is you method as simple as it sounds? Just a couple round stove top elements attached to the bottom of the tank and insulated to prevent heat loss?

It's very simple and easy to do, and NO fire or explosion hazard!

That's the key there, my father was VERY leery about using heater elements submerged. Seems simple enough as long as we have an easy way to control the elements. How much methanol do you recover from demething of the biodiesel itself?

Not a whole lot from the bio itself. Maybe 5-6%. The main reason I do it is because removing the Methanol from the bio causes any suspended soap to fall out, and cut's my Magnasol use by half! It also helps to keep moisture out of the bio. Methanol ATTRACTS water.

Just curious, what made you go with magnasol for your dry wash media? Between magnasol, purolite, amberlite, DW-R10 I'm not sure which to use. Also debating just using woodchips. I have 20' of 8" black pipe and a 13"x4' stainless induction tank sitting around, all possible towers.

I tried several systems, and like Magnasol the best. Just remove the Methanol, add the Magnasol and mix, then let it settle and decant the bio off and done! I have a Gas Chromatograph in my lab, and all my samples show that my bio meets ASTM standards.

Interesting, Ill have to look into that. How exactly do you remove the methanol from the bio? Just heat, or do you aerate it somehow?

It turns into a gas, and I recover it in a condenser. Then I reuse it...:D

I've been debating whether or not to design my setup to recover methanol from the bio. Will aerating the fuel, like with an aquarium pump, help get rid of the methanol faster?

One thing about methanol vapor, beside being explosive, it is very toxic. I think I would do that if there were no chance of spark and direct ventilation to the outside.

Yes, BUT, not a very good idea......Methanol vapors are highly toxic and explosive. Not something I want to put into the atmosphere even outside my shop........

If you recover the Methanol from your glycerol and your bio you can save about 1/3 of your methanol costs, AND have a safe system. A no brainer for me!

I would say so, now it's just a matter of building the setup. What about the purity of the methanol recovered? I'd be worried about having water or other contaminants. Would it make much of a difference if you just used half recovered methanol with half pure methanol for a reaction? Or is there another step involved here?

I monitor the temp and NEVER let it go over 200 deg. This is lower than the boiling temp of water and I haven't noticed any water problems. I DO use a half and half mixture of new and recovered Methanol though........

How many heating elements are you using and do you know what kind of wattage they are? Ill probably be heating anywhere from 120-200 gallons at a time. I think we use 2 1500W elements now to heat our oil, I would assume I should shoot for the same wattage range for distilling?

I've got two 1,500 watt eliments under a 200 gallon insulated tank. It takes about an hour and a half to heat up. Since I live in the eastern Oregon desert I'm putting together a solar heater for summer use for my main 500 gallon WVO storage tank. I think I can get all the heat I need during the summer months for FREE!

Well since I'm majoring in renewable energy I've got to ask you- what kind of solar heating system are you building?
As for the demething tank that sounds do able. Spring break is a month away and hopefully I can get everything built then.

I'm using a 4'X8' heat exchanger from an old steam boiler in an insulated box with a thermopane window, on the roof of my shop, and a smaller heat exchanger in the 500 gallon tank. I plan on using a 50/50 mix of glycerol and water for the transfer liquid.

I also plan on installing a valve set so I can transfer the heated fluid to heat the shop when I'm not using the tank.

I tried a small test last summer with a hundred foot coil of black plastic pipe on the roof of my shop, and developed 185 deg temps with a 4 gal/min flow.

185 degrees is pretty impressive. My partner was thinking about doing something like that himself...

That'd be something fun to build. I've got enough on my plate with switching to dry washing as it is though.

Forgot one simple question. How long does it take you to demeth your fuel? Im just looking for a roundabout number, trying to decide how to build the new setup.

Depends on how big your tank is.......:)

My old tank was about 40 gallons and took a couple of hours to finish.

I am thinking about 3 hrs or so. I need to make myself a more efficient condenser. It take awhile to heat up to 185 degrees, then I let it run until it slows to a drip from a steady stream.

That's about what I was expecting. What's the least amount of time needed to wait after the reaction to drain off the glycerine? It'd be pretty handy if I could do all that in one day, especially since the fuel would still be somewhat warm.

I always wait a minium of 12 hours before draining the glycerol. I've tried lower times, but always had more fall out later, so I wait the 12 hours now.

I've usually waited overnight, but browsing through some forums I saw people waiting just 4 hours to drain. I'll stick with the overnight and design the setup around that.

Do the same thing with the Magnesol. Let it settle overnight at a minimum and the filters won't have to be cleaned near as often...