Put some bio from an under-reacted batch on a hot plate WOW there was alot of bubbling for awhile when the temp hit 220F or higher but it settled down after about 10 minutes. Man I'm crappy when it comes to dewatering my wvo. Now I better dewater the BD (32 gallons) before I try any other HASTY moves. All I can do is heat to 140Fand pump with the drum lid open and a fan blowing across and keep testing on a hot plate.

How are you dewatering? If your heating and settling your getting a lot of water out, but not all of it. Water wants to get out of the oil but it needs to be pushed. Thus heating and spraying it is a good way to get it out. Pump from the bottom of the barrel to the top and spray it back in. You can use a fan to aid but it is not absolutely needed.

Heat,
As I understand it, you were checking water content after realizing the batch was under reacted. No water washing yet.

Tell me you weren't standing downwind from the boiling. That was most likely methanol boiling off. Of course some of it was probably water from the reaction.

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How are you dewatering?

I heat the wvo as high as it will go, which is @145f for about a day then drain off the bottom,but I don't really see much water. A hot plate test of the wvo didn't show any water so I thought I was allright to start the reaction. The method of heating and pumping over the top with a fan on is how it dry my washed bio in my wash dry tank. I'm going to rig something similiar for dewatering my wvo.

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As I understand it, you were checking water content after realizing the batch was under reacted. No water washing yet

Right, it hasn't been water washed. this was a single stage reaction for wvo that titrated 10. I'm going to try two stage next time.
Possibly acid ,if I canfind some sulfuric acid locally. I wondered if the bubbling wvo was methanol with the hot plate test but it didn't start bubbling until the temp was over 210F.

heatbeater
- If you didn't have any bubbles showing in the HPT prior to processing this batch, water won't be the reason the batch was under reacted. I would bet it has more to do with the starting T 10 is too high for single base processing. If your not going to do the acid treatment, then base base would be the next best process but the yield will be down due to soap. Tom

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then base base would be the next best process but the yield will be down due to soap. Tom

I'm thinking the same way. Base/base 50/50.

Heatbeater
I Use 80/20 for base /base-Its not true 80/20,I just mix all my methoxide at once and add 80% as stage 1 and the remainder as stage 2.I also pretreat the feed stock with glyc to lower titration and help dry the oil-my most recent batch I pre- treated twice(oldest gly first-heat ,mix for an hour,settle ,drain,then add glyc from most recent run,heat n mix for an hour,settle drain)obviously took out a lot of water as I had far less soap than normal(just shows how wet my oil is).
I find on 80/20-after first stage,some drop out of oil if I do a 27/3 test-but after dropping glyc then adding second part,I pass 27/3 almost immediately the methoxide has all gone in(my methoxide is injected into the pump so I achieve good mixing)-I still run it on for another hour just to make sure I have best conversion.Hope some of what works for me might help you.

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Posted 29 May 2009 03:37 PM Hide Post
Heatbeater
I Use 80/20 for base /base-Its not true 80/20

i think I should do glycerin pre-treatment to help lower titration and hopefully knock the water out. In the 2 stage reaction I guess draining off the glycerin helps raise the equilibrum. There's less dilution of the methoxide. Is that how it works?

When you remove the 1st stage glycerin,you are effectively stopping the reverse reaction(back to wvo + meth)When you add the second stage methoxide you push the reaction further to the right.

Hi Heatbeater
Here's some pics of recent "in process"(not washed)27/3.
The 2 on the right are regular 80/20- single glyc pretreat showing soap fall out on bottom.
The one on the left is from the 2 x glyc pre treat showing almost no soap fall out.
Hope pics are good enough to see.

27-3_001_(Small).jpg (21 KB, 26 downloads)

How long did it take for the soap to settle down? I didn't know the 3/27 would show soap?

i ran an under-reacted batch today.This batch was one that I water washed and dried before I did the reaction. I never water washed before,it was something I wanted to try because a small sample that I did water wash revealed some dirty water and a nasty looking layer between the oil and water. One of these days I'm going to get a camera so I can post pictures of different biodiesel samples.This batch was 33 gallons and I used 2 gallons of methanol and 235 grams of KOH. I always go heavy on the chemicals because I'm afraid if I don't use enough I'll be back to square one. The batch passed 3/27 within 30 minutes dispite the fact that none of the glycerine dropped out. I had this happen to me before and the glycerine came out in the first mist wash. I didn't know if that was going to mess up the 3/27. I thought that the 3/27 checks for bound glycerine which is evidence of reacted or under-reacted bio.( and I still think it does.)the suspended or free glycerin floating in the bio didn,t have any effect on the test. I always used to let the glycerin settle out before I pull a sample for the 3/27, but in this case I couldn't. So I learned a little more.

Heatbeater-when you say the glycerin didn't show-was that after settling overnight?When I do the second stage of 80/20 (settle overnight)there is not much glycerin-but there is always some(about as much as the vol of 2nd stage meth).
When I pull a sample for 27/3-I let it settle for 20 mins or so-you can see a small dark line of glyc on the bottom of the jar-I then take 3ml of oil from the surface.(the processor is left running until I have the test result)
I think what messed this batch up for you was the oil was still very wet from your pre wash with water and unfortunately it made soap at the expense of bd.
I would be careful going too heavy on the chems-otherwise excess soap will be made.
The recent batch I did with 2 x glyc pretreat ,the oil to start with was very wet and almost grey in colour(like an emulsion once it had been thru the pump)-after 1st pre treat it went to brown and after second pre treat it went to a light nut brown colour-for me this is my way forward from now on-(I know my oil is wet sometimes, as it is stored at the restaurant in open top cans outside-rain)-but I don't have oil titrating as high as 10,not sure how that would work-but I would give it a try.

This is the second time where the glycerin stayed suspended in the bio,allother reactions the glycerin will start settling as soon as I stop circulating. i can watch it settling down thru the clear hose that runs from the bottom to the top.