water washing

[hdj80 Senior Member Find all posts View Profile Close hdj80]

Re: water washing

geewizztoo
Well I have made 2 100litre batches since my last post and both have not had the 5% Glycerol pre wash. The last batch just went into the washtank to settle for a couple of days b4 washing. But the batch before...

Well the first spray wash was as soapy as the 5% pre glycerol wash batches but the washes after that got clearer and clearer, 2 Spray washes 20litres each and 4 of 20litre bubble washes. I used less water than usual also.
The result was very good BD back to bio of old. I have a photo that I'll try and post that shows 5 sample batches in below 10degC situation, the one on the left is before I tried this pre wash method the three in the middle are the Glycerol Pre-washed ones and the far right sample is the latest no Pre wash, see the difference. They all clear as the temp warms up.
So I am yet to be convinced that this 5% Prewash is a good thing.

Recipe..

WVO - 100 Litres
Methanol - 22%
NaOH - 5 g/l
Titration - 0.4
NaOH - 540 grams

http://www.biofuelsforum.com/attachm...1&d=1146017666

[geewizztoo Senior Member Find all posts View Profile Close geewizztoo]

Re: water washing

Hi HDJ80,

You must be relieved to have restored your original quality. I'm not sure why the pre wash method is not working for you, everything appears similar to my procedure except for KOH (and I don't think that's the reason). The only thought is that there may have been a little by-product remaining in your wash tank if it wasn't allowed to settle after transferring.

Was the picture of the 5 samples taken after washing, or are these straight from the reactor? The middle three look as though they are still wet.

[hdj80 Senior Member Find all posts View Profile Close hdj80]

Re: water washing

Was the picture of the 5 samples taken after washing, or are these straight from the reactor? The middle three look as though they are still wet.

These samples are after washing and they are all crystal clear in warm weather but when it cools off the 3 that had the Pre wash cloud.
Now another interesting thing is that when I filled up the 80 with my first batch of 5% Glycerol pre-washed bio the weather was quite cool and I had not checked the bio to see if it was cloudy or not. Well my filter on my storage tank plugged up and after I stripped it and took a look I was surprised to see this white substance all over the filter. Now I hit it with a hair dryer and it melted off into nice looking Biodiesel how ever it's gel point would be something like 30+degC as as soon as the heat was taken off it it solidified again.
Sooo I filtered out the cloudy Bio and may have dropped the gel point on that batch Want to see a couple of photo's????

http://www.biofuelsforum.com/attachm...1&d=1146021493
The white stuff came from one of the samples to the right of the first photo.

http://www.biofuelsforum.com/attachm...1&d=1146021493
After Hair Dryer

http://www.biofuelsforum.com/attachm...1&d=1146021966
Cold Morning

[geewizztoo Senior Member Find all posts View Profile Close geewizztoo]

Re: water washing

It looks as though the there was a lot of tallow or high melting point fats in the middle three batches. These would make high gel temp biodiesel.

Another thought, at what stage do you add the water to the pre wash?
Initially I had been letting my freshly reacted BD settle overnight, then add the water and remix. Recently I read that the water could be added on the fly - directly to the freshly reacted mix without settling. I have done this with my latest two batches and have noticed an increase of the dreaded white stuff (DWS) and it's been harder to wash.

I wonder whether adding the water when the glycerine is still uniformly suspended in the warm BD has the tendancy to make more soap? Since at any moment in time a small amount of water is being mixed with the reactants instead of sinking and dispersing into settled by product which would be mostly glycerine and methanol.

Previously I was adding the water into the settled glycerine layer and leaving it for about 30 mins before remixing. The temp of the mix would also be a lot cooler since it was left overnight before remixing. Do you think this could make a difference?

Maybe Terry_Syd would like to comment on your experiences please?

Also, on one of my 1L test batches I slipped & added too much water to the pre wash by mistake, probably 20%. This made a creamy mess initially but it still separated overnight OK. Maybe just triple check your water quantity.

[dillyman Senior Member Find all posts View Profile Close dillyman]

Re: water washing

Hi,
I would to also comment about results following the pre wash.I have now done 2 x 100 batches and on both have given me some emulsion. Titration remains the same at 2 grams,(KOH) Oil is cottonseed, same supplier, I have about 1400 Liters filtered pre stored oil, in new 200 Lt steel drums and settled for 3/4 weeks before using. Never draw from the bottom 150mm, this is settled in other similar near empty drums and stored. Processed for 2 hours with 20lts Methanol and 900 grams KOH (99%) then 5% pre washed circulated for 15 mins. drained the tubing ,pump, valves etc drain a little more from processor for sample bottle (750ml) Then both allowed to settle for 24 hours. Sample bottle is terrific, good glycerin separation almost clear drains and washes very well. About 30 litres of glycerin drained which is 10 litres more than no pre wash. The transfer to the wash tank is allowed to settle 14/20 hours with an addition 20 Lt's water( have tried Hot on one batch cold on other almost no stirring water added with 20mm siphon tube under the surface of oil.Very very slow stir in slow motion with a 50mm piece of timber. allow to settle. Greying water initial slight glycerin flow (just color-small) them chicken soup colour although thin and fluid. Another 20 hours and the top of the wash tank oil changes color quite quickly, but the remaining oil does not seemingly want to settle or separate. Am I missing something or doing something wrong? I can drain wash water from bottom and then the same thin color of creamy appearance. The bottle sample behaves perfectly and separates and is a rapid processing of quality stuff. Obviously the pre wash is not as good for me as a standard processing. I also tried a 300 watt SS aquarium heater to assist at one time but it had a negligible affect in a whole day and the thermostat at highest setting was cycling OK. Any ideas guys.

Hopefull

Dillyman

[Bio Popo Member Find all posts View Profile Close Bio Popo]

Re: water washing

Hi Guys,
I'm currently having some issues with my washing that I was hoping someone might be able to help me with.
Basically, it's just taking so bloody long! On one 20L batch on I'm on my 9th wash!! The first few though were the 'instant' washes where I added the water slowly, drained what settled instantly, and then re-added more water. I was using 4L of water. But for the last few washes, I've let the water settle for 7-15 hrs, and I"m STILL getting cloudy white wash-water.
My technique is as follows - I pour the water directly into the carboy (at first I gently added the water down the side), then I invert the carboy roughly a few times until the bio/water is homogenous. Then I let it settle and drain.
I've got 4 other batches that I'm washing at the same time and they're all taking a long time too - some are on the 5th wash and others are on their 4th, with still no signs of the water becoming clearer.
For one batch I did a 10% pre-wash immediately after processing, and although I've only done one was so far, it's wash water already appears the clearest (although I've been very 'UN-scientific' and there were a few other variables about this batch).
So basically, I'm wondering what the f#ck is going on! It really shouldn't take so many washes right? I mean, with the nine-washer, I've already used 36L of water!! That's almost 2-1 with water to bio!

One thing that I've thought might be causing some issues is the fact that when I drain off the wash-water I cannont get ALL of it. Maybe 250mL is left behind each time and then subsequently remixed in with the next wash. Could this be delaying things? I've re-worked my draining method on the last wash to avoid this.

Also, just to make this post THAT much longer, I've noticed a BIG decrease in the amount of bio in the carboys since I've started washing. In one case, I know that there was exactly 15L of bio after reacting and draining off the by-product, but now after a few washes, it's looking more like 8L! Is that normal? I'm pretty careful when i'm draining off the wash-water so as to not also drain a lot of bio, so I certainly haven't lost more than 500mL that way, so does that mean that 7L of my bio was actually contaminants that are being drained out in the wash-water? Could that mean I'm using too much KOH or methanol? (currently using 7.8g/L as a base for my 90% pure KOH, and using 20% methanol).

wow, that was a long post, thanks for any info guys and gals!

Dave

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: water washing

De'ja' vue

Tilly

[Terry Syd Senior Member Find all posts View Profile Close Terry Syd]

Re: water washing

The dreaded white stuff is caused by monoglycerides and water combining. If you do not get the DWS without the pre-wash, but do get with a pre-wash, then it is likely that the pre-wash water is being added too soon.

A monoglyceride is the next to last step in the transesterification process. The oil starts out as a triglyceride, then diglyceride, then monoglyceride and finally a glyceride (glycerin drop-out).

DWS can be cleared by heating it.

The biodiesel cloudiness on cooling may also be related to monoglycerides left in the biodiesel. The monoglycerides have an affinity to water, there may be small amounts of such water laden monoglycerides dispersed in the biodiesel. Perhaps not enough to create a visual DWS cream, but enough that when the biodiesel cools their dispertion in the biodiesel makes it cloudy.

Increased temperature, aggitation, time, catalyst and methanol all contribute to increasing the conversion rate. When you add the pre-wash water, the reaction stops. Period, full stop, like a light switch going off. You just limited the amount of time for the reaction.

Getting a good drain of all the milky wash water is very important. If you use, say two litres of wash water versus four litres, then the glycerin concentration in the wash water is twice that of the four litres of wash water. If you leave a small portion of the wash water in the tank for the next wash, then the glycerin in the residual wash water contaminates the next wash. Theoretically you could continue this process infinitim and still never get all the glycerin out.

Whether it is removing the glycerin or the water from a wash, if you do not allow enough settling time, there will still be a little biodiesel left in the glycerin or wash water which will be lost when you drain it. This will reduce your yield. (think of that thin layer of biodiesel on top of your stored glycerin)

If only we had little centrifuges available, we could just run the 'unwashed' biodiesel though the centrifuge and be done with the process. The Earth's gravity will also seperate the glycerin, it just takes a lot longer. Many people who run 'unwashed' biodiesel let it settle for a minimum of a week, longer is better.

We are all in a rush these days, but I expect that most of the above problems in production could be cured by a bit more time.

[Bio Popo Member Find all posts View Profile Close Bio Popo]

Re: water washing

Ok, so if I've read your thread correctly Terry Syd, you're telling me that 1) I need to let the wash settle for awhile (what's an 'acceptable' time? 5? 7? 12hrs?)
2) I need to completely drain the wash water after each wash

This will cure my problem?

I thought last night that maybe the problem was because I hadn't agitated the water/bio mix enough after adding the water (because they all tended to separate almost instantly), so I shook each one really roughly and thoroughly mixed them.


Here is a picture of the wash water that I drained off one of my batches last night. I believe it's my 5th or 6th wash on this batch.
You can clearly see a section of 'soap', but strangely enough there was no such soap section visible in the actual processor.
Ok, well the computer I'm on isn't working and I can't upload the picture, but basically the water is fairly soap, then there's an inch or so of thicker soapy stuff, then a small layer of biodiesel. How come the soap wouldn't also be in the processor though? (By processor I mean the settling tank).

Dave

Dave

[Terry Syd Senior Member Find all posts View Profile Close Terry Syd]

Re: water washing

Dave, emphasis on number (2). Drain all your wash water, see how that affects your subsequent washes.

The first wash settling is the most important one, that is going to contain most of the glycerin. It is also the one that the soapy water is going to more strongly resist dropping out of the biodiesel. If you are going to leave any wash to sit longer, do it for the first wash.

[dillyman Senior Member Find all posts View Profile Close dillyman]

Re: water washing

Hi Terry Syd,

Would you clear something for me. After the pre wash and the processor settling drawing off glycerin and transfer to wash tank. Is it better to allow the oil to stand without the addition of water in the first instance, also how long should it be left to settle. I think my stuff up is not allowing the transfer to settle long enough. I also have added water straight away after transfer. Too keen to get it going. My main prob is the top oil in tank is settling well but the lower oil still appears homogeneous to some extent. That is what does not seem to change much. Doing a bottle wash with this stuff seems to go striaght through and clear water. Any suggestions. Am I trying to rush things perhaps. My normal processing is OK, and the pre wash samples are excellent. Would be a pity to foul up a good process by my own stupidity.

Appreciate some candid response.,

Dillyman

[Terry Syd Senior Member Find all posts View Profile Close Terry Syd]

Re: water washing

I can only offer some general principles and ideas. Each person has their own processor with its own aggitation system, they all use different feedstocks and react at different temperatures and with different combinations of methoxide. Specifics are hard to nail down.

As far as adding the water, when you feel the reaction is finished, then add the water. You don't need to let it sit, the reaction is finished so you might as well get on with the next step.

Since hurrying the process can result in big mistakes which have to be rectified, it is better to error on the side of caution and allow more time for the various processes.

[bj4408 Member Find all posts View Profile Close bj4408]

Re: water washing

Hi Dillyman
I do the the 5% prewash also. Then let settle overnight drain off glycerine then transfer biodiesel to wash tank. I then wash straight away and let settle for 24 hrs and repeat 2 more times the last wash may only settle for 8 hrs depends what I am doing.
I find that when draining the first wash water the biodiesel is clearer at the top but there is a distinct water layer. The lower biodiesel seems to have a lot of fine water droplets in suspension which can at first seem like a weak emulsion(seems to be more when I use prewash).Put some in a glass and hold it up to a light and see the droplets floating around.
When drying these fine droplets take several days to settle out depending on temperature. To speed it up you could heat it, a good way to do a quick test is to put some in a glass jar and warm it in the microwave and see if it clears, the water forms big droplets on the bottom. I am now trying bubble drying with an aquarium pump and length of tube with pin holes in it. I leave it going all day while I am at work. First batch it has definitely saved me a few days of settling time.

As you said your samples are clearing OK, you must be on the right track. Give it time to settle. Use a second wash/drying tank if you need to process more, thats the way I am headed.
5% prewash has only made things easier for me.

Hope this helps

[dillyman Senior Member Find all posts View Profile Close dillyman]

Re: water washing

Hi Terry Syd,

Thanks for your comments, I realize there are many variables. Today I have continued to allow the wash tank to settle (now 2.5 days) I must admit that what I thought was unchangeable orange juice has in fact thinned somewhat, and still drops out some more water, time does in indeed assist the process when one has been hasty and impatient. To check this, I drained the bio from the bottles above the Glycerin on the two sample past batches, they have been standing for a few days. When decanted, the bio was very shiny and reasonably clear, boy! did its first wash go well, and when agitated did not even lose its glossy appearance but the water started clearing well. I look forward to the next wash tomorrow which I believe it could be its final wash. Undoubtedly most of the problems I have encountered have been a result of my rush to get it done. It is clear to me that good settling for reasonable time on the first wash and a bit less hasty action certainly pays off. It seems I have been suffering from rushing and doing too much ( I have no need to I have full tanks and 200 liters drum half filled. I have, to hasten things, installed 2 x 200 Litre natural color wash tanks. I will be better able to observe the process and progress, also to be able to manage my stock much easier with much less haste. Theres no fool like an old fool. Maybe I will now learn to be patient as the process will certainly benefit from less rush.

Your comments are greatly appreciated.

Cheers!

Dillyman

[Bio Popo Member Find all posts View Profile Close Bio Popo]

Re: water washing

Hello hello,
Well, after hearing from Terry Syd how important it is to drain ALL of the wash water, I realized that this was impossible for me because of the design of my processor/settling tank (a 20L carboy). So I adapted a washing method that I know Darren from the Melbourne Biodiesel Club (a little plug for them!) uses. Instead of doing multiple wash of say 20% water to oil volume, I do slowly add 1:1 water to oil and slowly drain off the water. I used a camping solar shower and plugged some holes so that it would drain slower. I've put up some pics of this setup. Well, I'm ecstatic to say that the washes came out crystal clear by the end, after a lot of soap came out. I collected some samples in a jar and the biodiesel separated quickly and sat on top of crystal clear water. I've posted pics of them as well.

However, this morning (after washing last night), I noticed that one of the samples I had taken previously now had cloudy water in it. As well, the container that I collected all the wash water in (had clear water on the bottom and a layer of soap and bio on top) was also now cloudy. It WAS mighty chilly last night in Melbourne, so I don't know if that has anything to do with it, OR if it means that there is still soap in the biodiesel even the wash water came out clear! Anybody? I also noticed that it appears additional water dropped out of the biodiesel overnight, enough that I was able to drain some more. That mean anything?

Well now I am drying. I am using an aquarium pump where I tied rocks to the end of the tube so that it would sink to the bottom. It's been drying like that for 24hrs now but is still cloudy. There is some (100-250ml) water still on the bottom of the carboy that I am unable to drain, is this impeding the drying process?
bj4408 I am curious about your method of poking holes in the tubing. I guess this would give you MORE bubbles that are FINER? Is this preferable to larger bubbles coming from a central location?

The picture of the REALLY soapy wash water is the kind of results I was getting doing the washing the other way (adding 15-20% water, agitating, and then settling overnight)

Thanks guys and gals,

Dave