How water soluble is glycerol?

[Cheaper Jeeper]

I'm looking at how to best use my newly aquired hardware to set up my process. I'm at least going to start with mist water washing and here's what I'm thinking of for my process.

Make 50 gallon batches in the 80 gallon HW heater based reactor. Reactor vent line discharges into 50 gallon HW heater based methanol recovery still for capture. Run at 160*F continuously recirculating with the pump for 2 hours (longer? shorter?).

Once the reaction is complete, pump the reactor contents into 70 gallon cone tank for settling.

Once settling is complete pump glycerol from cone tank into 50 gallon HW heater based methanol recovery still.

Water mist wash bio in 70 gallon cone tank & allow to settle.

Once settling is complete pump soapy water from cone tank into 50 gallon HW heater based methanol recovery still. Assuming glycerol is fully water soluble this will help thin the glycerol and keep it from gelling in the tank.

Pump bio back into reactor and heat/circulate to dry fuel and drive off unreacted methanol (not sure if there will be any after water washing?). All vapors from reactor will continue to be vented into methanol recovery still for capture. Continue to heat and circulate at 160*F until methanol recovery is complete (is that the right temp? Higher? Lower? For how long?).

Heat and circulate wash water/glycerol mixture in methanol recovery still to boil off methanol and recover methanol from vapor discharged through a condensor that is being chilled by cold water. Possibly with a vacuum pump installed between the still and the condensor to speed up the process.

Pump finished fuel from reactor into storage.

Pump methanol-free soapy water/glycerol mixture from still into drums for disposal.

SO, is there anything I'm missing?

Any steps that should be changed?

Any better ideas on how to run the process (excluding dry washing - we may do that but aren't going to be ready for it right out of the gate)?

Any and all opinions welcome.

 

[bbressler]

I think you'll need to wash more than just the one time...

I would mist-wash (about 10% water), then start an airstone and bubble wash for 6 hours...I did that three times usually and it was good.

As far as my experience, glycerol is water soluble, It's a good idea to pump it into your still to recover that methanol. I've never recovered the methanol, but 160 should be alright -- boiling is 149...

For drying your bio, you can really speed things up by the way you are returning the fuel to the tank...the more surface area you can provide, the faster it will go..

 

[Cheaper Jeeper]

I think you'll need to wash more than just the one time...

I would mist-wash (about 10% water), then start an airstone and bubble wash for 6 hours...I did that three times usually and it was good.

WOW! 3 wash cycles of 6 hours each? How much settling time in between cycles? Did you do any methanol dissolving tests in between wash cycles to see if another cycle was needed, or did you just do 3 cycles to make sure you got everything? 3 wash cycles @ 6 hours each just seems like overkill and a LOT of time spent on washing. But since I'm a rookie, I'm open to learning what it really takes.

As far as my experience, glycerol is water soluble, It's a good idea to pump it into your still to recover that methanol. I've never recovered the methanol, but 160 should be alright -- boiling is 149...

Good info. Thanks for the confirmation.

For drying your bio, you can really speed things up by the way you are returning the fuel to the tank...the more surface area you can provide, the faster it will go..

Yeah, for the drying cycle I plan on using the reactor, but rather than pumping out of the bottom and having it just "dump" into the top (like it will be for the mixing & reaction cycle), I'm thinking I may want to put it back into the reactor vessel through a separate inlet that has some kind of a spray nozzle to speed up the process. I will probably be doing it under vacuum as well. How hot can you safely heat the bio to drive off the water without hurting the fuel?

 

[bbressler]

I let it settle for about 6 hours after each wash.....although the time required for each subsequent wash goes down a bit...

Here's my thinking on the wash part. You're putting in clear water. Until the water comes OUT clear, you are still removing contaminants (soap, lye, methanol, other?) that you don't want in your fuel. Can you get by with less? Sure.... but I feel most comfortable with my fuel KNOWING that I got everything out that I could. When I first started, I tried one wash and I plugged a 10 micron goldenrod filter before I could fill up a 5 gallon jug. That scare kind of kept me in check. My fuel looked clean, clear & dry, but obviously it wasn't.

On my reactor, I used a 55 gallon drum, and I returned from the pump through the center of the top of the barrel. I came in 1" pipe, to a Tee, and out 6 inches or so with more 1" pipe and capped them. Then, I drilled a bunch of small holes -- maybe 40 - 50 of them. In my setup, this helped make sure the mix was really happening well. I didn't dry in that tank (I bubble-dried)....but if you ran through something like that, the splashing it causes and the bunch of little streams sure would increase your surface area. I can't figure out how you'd get one of those inside a HWH, though... I have seen some folks just mash a pipe in half so it fans the fluid out, that'd be a good idea, too.

As far as heat, I've got BIO up to 200 degrees with my WVO conversion....no problems there. I'm not sure exactly how high you CAN go, although I suspect its quite a bit higher than I've ever gotten it.

 

[Cheaper Jeeper]

That makes sense on the washing. I'm wondering if 2 washes with a little more water (say 15%) wouldn't accomplish the same thing though...

On the wash bubbler - you are talking about bubbling air up through it, right? Why agitate it that way instead of just misting with a larger amount of water? Seems like bubbling would make it take a lot longer to settle.

Lastly, you're air bubbling to dry too? With or without heat? Seems like a slow way to do it.

Sounds like your process could be compared to "hand crafting" as opposed to mass-production...

 

[bbressler]

Yes, more water in each wash should help to limit the number of cycles required. Once wash water is so dirty, it won't pick up any more stuff.

Yes, bubbler on bottom bubbling up through the misted water. My bubbler is using one of those wood stones, and it doesn't really agitate as much as you'd think. It's very gentle. I'm not sure it increases the settling time over just mist-washing.

Yes, I bubble dried. No heat. Kind of slow, but I could get it done overnight, usually. Takes a lot less electricity (and I don't have to sit there and watch it to make sure it doesn't run dry, pump quits, etc...) Slow has two meanings for me....slow my time, or slow mechanical time. I'd rather it take a longer time unattended than have to baby-sit it for a shorter (but still long) time. I normally spent 30 - 45 minutes per batch of actual work, sitting around waiting for stuff to happen.

Yes, hand-crafted would be a great description. That's one of the reasons I went to WVO... On a regular basis, I could process a batch from start to finish in under two days. It was pushing it, though.

I got into the biodiesel thing a while back, as fast as the technology is changing, I'm sure a lot of what I did is old history by now, and there are lots of good ways to do things.

 

[Cheaper Jeeper]

So you quit making bio and went to burning the oil straight? Are you blending or did you modify the truck as a 2-tank setup? Why would you give up on bio if you had it up and running like that? I don't understand...

 

[bbressler]

Yep. Installed a plantdrive two-tank kit and burning it that way. The biggest reason I switched was time. I had stockpiled up several hundred gallons of oil and didn't have the time to do it. Other benefits of WVO (for me) were not having to buy methanol, an every-increasing commodity here. I was almost up to $1 a gallon in supply costs alone. Also, without heaters in my truck, I was only able to run BIO during the summer months, so that really limited how much I was able to use. I only have one vehicle in my fleet running diesel, so I didn't have the multiple vehicle justification like some folks do. There just seemed like a lot of positive benefits I would gain from switching to straight oil. Had I had another vehicle, I wouldn't have stopped.

 

[Cheaper Jeeper]

Yep. Installed a plantdrive two-tank kit and burning it that way. The biggest reason I switched was time. I had stockpiled up several hundred gallons of oil and didn't have the time to do it. Other benefits of WVO (for me) were not having to buy methanol, an every-increasing commodity here. I was almost up to $1 a gallon in supply costs alone. Also, without heaters in my truck, I was only able to run BIO during the summer months, so that really limited how much I was able to use. I only have one vehicle in my fleet running diesel, so I didn't have the multiple vehicle justification like some folks do. There just seemed like a lot of positive benefits I would gain from switching to straight oil. Had I had another vehicle, I wouldn't have stopped.

That makes sense. If I were just doing it for my truck I might go that route too. They are really set up well for a two tank system. Plus I don't drive it that much either, so going to the trouble to brew bio might not be worth it if it were the only rig I wanted the fuel for.

BUT, with my 84 Mercedes 300CD Turbodiesel going straight veggie isn't so easy. Since it is my DD, I really want a steady supply of fuel that it will burn. It only has one tank so adding a second tank means giving up about half the trunk space - and making some fairly permanent modifications - both of those are things I'd really rather not do.

I thought about doing a one-tank system, with thermo-controlled injector line heaters to heat the oil at startup and until everthing is good and hot, and a hot water heat exchanger to keep the oil hot once the engine is warmed up. I read enough about cold veg oil and the bad things it does to discourage me from going that route. I decided to just use my SVO for blending until it is all gone and then go with WVO based bio after that. I'm not even blending the SVO right now because I paid just under $3 a gallon for it when #2 was up around $5 a gallon, and now even regular #2 is cheaper than what I paid for the SVO! I'm going to save it until prices go up enough to make burning it cost effective again.

Around here bio blends up to 50/50 are pretty much good year 'round. With a supply line heater and heated fuel filter even B100 is OK year 'round.