So..i finally am getting consistent 3/27 passes with my GL 1 system, but i seem to be stumped with the final soap removal part.

I am doing de-mething of my bio after glycerin removal, and according to GL, if i remove the methanol adequately from my bio, any soaps should drop out during the following 3-day settling period.However, there have been several occasions when i finish distilling out the methanol, and i go to drain off the bio, and notice huge amounts of frothy soap suds..a lot of which stays in my processor.

I thought that maybe the soap would all settle out of my bio eventually, but theres still plenty in solution a number of days later.

One of my thoughts is that i am perhaps de-mething at too high a temperature. I discovered that the problems that i was having getting a consistent 3/27 pass in my mixing stage was due to having my temp too high - i dropped it 10C, and bingo - passes every time. Could this also be the problem with my de-mething cycle? Graham Lamming suggests that the temperature should reach 90C for complete de-mething. I am using the venturi in the process..so its more evaporation than distillation. I do have another thermometer in the head of my plumbers delight still, but it generally stays at 60C when i use this process.

The other thing i notice is that i begin to get a small amount of bio in my distillate towards the end of my de-mething.

My oil titrates at 3.5, its perfectly dry, i add 8.5 g of NaOH and 20% methanol per litre, using a 2-stage 80/20 base-base process, doing 180 litre batches, and have very good 3/27 passes.

any suggestions would be most welcome.

cheers

richard

The soap coming out while demething is normal. I have a large open impeller pump and even it groans as it chops up an pukes out the soap chunks. If you do the WBD or push/pull the soap will stay in the glycerin and comes out when you drain it leaving very little in the fuel eliminating your issue.
I always bubble air through my biodiesel overnight after draining it from the processor to drive off the last traces of methanol, it then takes a minimum of 3 weeks before the soap gets down to around the 150PPM level. The 3 day settle time is nowhere near long enough in my experience.
I process using NaoH on 100L batches using 22% methanol.
It goes against my experiance and what I have read that lowering your temp would give better conversion. The higher the temp the faster the conversion and vice versa. If you go above 170F you will be boiling off methanol and that could have detrimental effects on your process. I process at around 150+F for 3 hours with great results...
Jon

Hi richard,

I have had this a time or two. If you are getting bio in the distillate there is a bunch of foaming going on in the processor. Usually after these batches have settled I find more solid glycerin in the bottom of the settling drum along with the soap. I know if you are doing push pull you are heating the whole mix anyway but I think in our situation the very small percentage of glycerin may be responsible for the foaming. I only have this problem when I short the settling time and don't get all the glycerin out. 150l batch, 22% methanol, titration usually about 4 naoh, 145f process temp, 200f demeth temp.

Tony

hi

Jon:
I dont usually get sudsy soap froth in my bio or processor - but its been frequent enough to wonder what the problem is. Generally after de-mething my fuel goes into my settling tank, and i take a small sample in a jar. After three days or so, there is a solid deposit in the jar. When i then take a sample from the settled batch, and do a shake-em-up test, the water settles out nice and clear with no middle emulsion (soap) layer.The reason i thought temperature might be an issue, is that when i get oil in my distillate, i thought the temp was hot enough to start evaporating the bio into my distillate.

tgomes:
My setup is similar to yours, with the exception that i am using GL's suggested external heater. I did ask him when i built it if he thought that there would be problems with residual fluid left over from the previous batch trapped in my external heater tube. He didn't think so. However, before i did my recent failed batch, i had been de-mething my glycerin, so there may well have been enough left in my heater tube to cause the problem you suggest....but i figure that it would get taken up in the mixing stage with the next batch's oil. Generally i leave my finished bio to settle overnight before i drain off the glycerin....but i may have not done so with the failed batch (got to try to remember..perhaps i should keep a diary!).

I have started doing the 2-stage 80/20 base/base because i have some oil that titrates high. i havnt used the whole-batch de-meth yet, or Grahams push-pull design.

Tony makes a good point about the foaming!
Also if you have been brewing for awhile now and this is the first time you have experienced allot of soap it could be that your titration solution is getting week causing your titrations to go up thus creating more soap because of too much caustic? Just a thought...
Jon

I have also started doing 2 stage. Since the economy went to crap it seems my sources are using the oil longer. What used to be 2 to 3 is now 4 to 6. Not a problem to process but the yeild sure does suffer.

Richard.... Are you bubbling at all in the settling drum? This does seem to really help with the soap settling.

Tony

Dicko,
I get these stingy frothy soap suds too when demething just the biodiesel - and a lot too..To clean out my processor I put in some hot acidic water and let settle for a 30mins or so. Drain. I dont use a hot water heater so im not sure how good urs could drain if u put water in you processor?
I guess you could then flush with a few litres of glycerine...

Like Jon and others said, that bubbler really helps a whole lot. I leave mine a few inches off the bottom off settling tank. I get very good results when i do this

Another thing, keeping the biodiesel fairy warm with the bubbler in really speeds up the drying..noticably.. gets rid of residule water and methanol lots faster..

hi all

thanks for all your feedback.

I just got an aquarium bubbler last week, and have used it once overnight. I got the smallest one - i read somewhere that you only need something like a 3-watt bubbler. I bought a 4-pack of airstones to go with it, thinking that more would diffuse the bubbles better - but the little t-joints broke..effectively making just one big bubbler in the centre!

Tony:
The other thing i have managed to do since changing to 2-stage is to reduce my methanol consumption. I cut down from 22 to 20%, and from what i have read on this forum it seems possible to reduce it even further. Interestingly the best 3/27 passes i had (just kept on dissolving bio well beyond the 1:9 ratio) were with oil that had glycerin pre-treatment. I did two 50% cold treatments on some oil titrating at 10 - brought it down to 3.5.

Jon:
My titrations seem to be bang-on, as i usually do a mini-batch before i make any changes, and they worked well with the titration i had measured.

Reece 123:
I used compressed air to blow out most of the froth in my processor. I have a small inspection port (where the lower element used to be), and when i looked in with a light, it seemed that it was pretty well all gone. I have also sprayed warm water inside the same port which dissolved most of the froth.A pain in the ass nonetheless.

cheers

richard

cheers

richard

Interestingly enough I had the same problem, and for me three weeks of settling time is to much. So I went back to water washing. What I found is that my water washing goes much quicker than it used to. When I had a standard appleseed. It took me three to five washes to get it clean.

Demething the bio helps the soap drop out, so the water picks it up more readily. I usually wash either twice or three times and I'm done. The first wash is static on 145F water, and it comes out very dirty. Second wash is usally just barely milky, like you forgot to rinse the milk out of your glass before serving water. and if I wash a third time it is almost always crystal clear, meaning I didn't need to do it. I start bubbling on the second wash and I keep the temp up the whole time.