water washing

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

Re: water washing

You can see from the pictures of geewizztoo that the first pre-wash did a good job of eliminating the glycerin/soap from the biodiesel. If he had allowed the biodiesel to totally settle and then drained off what precipitated out before he did the first water wash (that is, let the biodiesel clear), I would expect that the first water wash would have been even more impressive.

Perhaps he might give that a go and post the results? Geewizztoo?

Terry, yes the initially wet BD does clear given enough time and is seems very dependant on ambient temperature. Typically it takes a week or two at summer temps but maybe longer in winter. Personally, I prefer to follow through with the washing and drying routine because it's quicker than letting it settle. I find if the BD is allowed to stand on top of water, It 'clouds' when chilled. I'm assuming this is because there is still a minute amount of water present. I've attached a photo of some BD which has been washed just once and has been sitting on top of the water for about two weeks now. As you can see it's crystal clear.

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

Re: water washing

Thanks for showing us that the water will eventually settle out, and yes, temperature has a lot to do with it. I've had biodiesel that has settled out over night when the temperature has dropped during the night.

The picture you showed is after the first wash following a pre-wash. It shows a slight cloudyness in the wash water because of soap. I expect that you did the first water wash without allowing the fine droplets from the pre-wash to precipitate out of the biodiesel.

My point was, that if the biodiesel is allowed to completely settle after the pre-wash, then the first wash would be even more impressive.

The reason I mentioned this is that some people simply do a pre-wash, drain the glycerin and then let it settle until clear. They might do this by processing, doing a pre-wash, decanting the glycerin and then decanting the biodiesel into another vessel to further settle out. This is similar to using 'unwashed' biodiesel, that is by giving it further time to settle.

However the pre-washed biodiesel that is settled will always have much less glycerin in the biodiesel than unwashed biodiesel that has settled. This may be enough in your vehicle to prevent any filter clogging problems.

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

Re: water washing

Hi Terry Syd and Geewizztoo,

Like Joe I am very impressed with the pics of the comparison washes. Looks great! Could you clear up for me , When you have added the 5% of water and circulated again for 15 minutes, how long would you settle before draining off the pre wash? It does seem good sense as the process should have been completed by then. Glad you mentioned the bright colour of the oil after the process I think I would have been very surprised by that should you not have mentioned it. Terrific results, I would certainly like to achieve those kind of results myself. Thanks Guys!!!

Rgds

Dillyman

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

Re: water washing

After the addition of the 5% water and further mixing, the glycerin level will settle faster than the original glycerin settled. You will probably be able to start tapping off glycerin within 10 minutes. However, it is better that you allow a long period, overnight if possible, to get most of the glycerin/water out of the biodiesel.

After decanting the glycerin, the biodiesel will remain a bit cloudy until the fine droplets settle out. If you want to use it immediately and not have to worry about the fine droplets settling out in your tank, you can add a bit of alcohol to the biodiesel to put the droplets in solution. 1-2% of isoprophol alcohol would probably do it. You can also use other alcohols including 'menthylated spirits' (95% ethanol, 5% water) to put the droplets in solution.

[bj4408 Member Find all posts View Profile Close bj4408]

Re: water washing

Here is my test sample of 5% prewash, this is 10 minutes after 2nd full wash.
The sample was treated with 6g NaOH then I prewashed half,(sample on left), let settle, drained glycerine layer, washed(definately not gently), settled then drained water, then another vigorous 2nd wash.
I was amazed at the result this is my second trial of prewashing with a similar result each time. It has given me the confidence to go on to 20 litre batches later this week. My previous samples had always been requiring 5 washes to get get good results. With prewash I think 3 at most. A major time and water saving.
Thankyou all for the good info. In 4 weeks I will have gone from my first look at biodiesel on the web to small scale production. Only possible because of the good quality info that is out there.

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

Re: water washing

Hi Terry Syd

I am getting more impressed with this prewash the more I hear. Could you advise me ? You recommended that 8 hour of overnight settling would be prefered. Would the end result be better if the temperature was left constant during this settling time? I suppose I could ask the same question for the following washes, would constant temperature assist or not during these processes?

Many Thanks

Dillyman

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

Re: water washing

I hope Tilly steps in here soon. I do not think that keeping it at a constant temperature while it is settling will help at all. In fact, I have had better settling when the temperature dropped overnight.

Keeping the temperature constant while processing is a good idea. It can increase your conversion rate by a small amount. However, once you add the 5% water pre-wash all conversion stops.

Please remember that if you are trying to hurry things along. Once you add the water, there will be no more conversion, the reaction stops.

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

Re: water washing

I am going to do it! Pre-wash that is...

Also I have pulled my Processor to bits and rebuilt it so now it will drain much better....Yes I had a slight emulsion problem last week caused by (what I believe) to much Glycerol in the wash tank. I can almost see all your heads nodding in "we told you so" fashion....

My next Processor is going to have welded plumbing and taps, none of these pipe sockets, bends and Tees etc to catch Glycerol.

I can do this now because my wife has told me that it is no longer a money saving exercise but an Expensive Hobby - Never thought myself as a Hobby sort of Guy.... I brought an Walbro electric Fuel Pump to act as a pusher pump and she saw the $208.00 invoice.

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

Re: water washing

Peter, the prewash does seem to do a few things, I must admit I have only played with it but I do believe it can do many things. I know that you should not do it twice it can cause wash problems ie emulsions!

Anyway ask the wife why is it an expensive hobby? After 18K litres of fuel I have almost payed off the renovation necessary for my setup. Its savings all the way.

Matt

I am going to do it! Pre-wash that is...

Also I have pulled my Processor to bits and rebuilt it so now it will drain much better....Yes I had a slight emulsion problem last week caused by (what I believe) to much Glycerol in the wash tank. I can almost see all your heads nodding in "we told you so" fashion....

My next Processor is going to have welded plumbing and taps, none of these pipe sockets, bends and Tees etc to catch Glycerol.

I can do this now because my wife has told me that it is no longer a money saving exercise but an Expensive Hobby - Never thought myself as a Hobby sort of Guy.... I brought an Walbro electric Fuel Pump to act as a pusher pump and she saw the $208.00 invoice.

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

Re: water washing

Anyway ask the wife why is it an expensive hobby? After 18K litres of fuel I have almost payed off the renovation necessary for my setup. Its savings all the way.

Matt

We all know that (I hope she does) but if she say's it is my expensive hobby then I no longer have to explain every cent spent. This now opens the way for a long awaited Intercooler for the 80. I'll just have to tell her it's a turbine filter due to the extra power the bio gives the beast the more likely the turbo will blow sending pieces of turbine fins into the engine so a filter is required to prevent an expensive engine rebuild.... . But I am afraid she isn't that stupid so I'll just have to add up my savings by making bio then once I have paid for the setup I can then put together a case for the intercooler.

[joe Moderator Find all posts View Profile Close joe]

Re: water washing

I've made and used heaps in the last month. I reckon I've saved 120-130 in the last fortnight alone. I've only had to chuck in 10 or 20 bucks. I seriously wondering what to do with the extra cash. I'm considering investing in the Australia Biodiesel Group on the ASX. They gone up 20% since December and the other Biodiesel mob (not sure what they are called, their ticker is ARW) have gone up 40%. They've both gone up since the Marickville station started pumping BD.

Joe

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

Re: water washing

Well I have done this 3 times now and every time I end up with a big job washing the fuel. I really have no idea why you recon this is a good idea as the last 2 batches must have taken over 300litres of water to get the fuel to a usable state.
After the second go I thought the problem was with the NaOH I was using but this morning I have decided that it is this pre wash as all previous batches have had no problem's.
So now I have a week of washing ahead of me and my next batch will not have this prewash. So far it sucks for me.
And before you ask I mixed for 2 hrs and added in 5litres water into the 100litre oil, mixed a further 15mins drained the glycerol and after the first spray wash it was evident that I had a mess......

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

Re: water washing

And before you ask I mixed for 2 hrs and added in 5litres water into the 100litre oil, mixed a further 15mins drained the glycerol and after the first spray wash it was evident that I had a mess......

Hi HDJ80,

Sorry to hear that the prewash method is not working for you. It must be very frustrating. Can you expand on the above?

How long after pumping the BD into the wash tank do you start to wash?

I leave mine to settle for a further 24 hours before I add water, just to be sure that any residual glycerine has settled to the bottom. The action of pumping from one tank to the next can stir up small amounts of glycerine trapped in the nooks & crannies of your plumbing.

You also called it a 'spray wash', how aggressive is this spray? It should not break or disturb the surface of the BD. It's supposed to be a fine mist. I use the nozzle from one of those cheap pump-up garden spray bottles attached to an irrigation hose. After the mist water has settled, I let it stand for another 24hrs before I drain the water. The water has usually turned grey/beige with the small amount of dissolved glycerine. I mist again then start to bubble wash with the second lot of water.

Do you follow up with a few bubble washes? Misting alone will take large quantities of water and is very time consuming.

Also, what does this 'mess' look like? The wet BD from the prewash already looks like orange juice and when I do my first mist wash, the BD goes very creamy looking, like caramel. Sometimes with a few floating white bits. This was quite alarming the first time I saw it.This gradually clears with 48 hrs of bubbling and 3 water changes (20L each). Washing and drying normally takes me about 4 or 5 days, but then I'm in no rush.

The only other difference is that I use KOH catalyst which I've heard is more forgiving. I've also read that if the first wash water is slightly acidic, then emulsions are less likely to form. You could try adding a little vinegar, although I haven't tried this personally.

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

Re: water washing

geewizztoo

I have answered your questions in Italics

How long after pumping the BD into the wash tank do you start to wash?
Straight away

You also called it a 'spray wash', how aggressive is this spray?
I use 4 small garden mister's - You know the type that screw into black pollypipe.

Do you follow up with a few bubble washes? Misting alone will take large quantities of water and is very time consuming.
Mist and then bubble wash

Also, what does this 'mess' look like?
Not really a mess I was incorrect stating that. It is processed Bio with heaps of soaps in it. No emulsion.

The only other difference is that I use KOH catalyst which I've heard is more forgiving. I've also read that if the first wash water is slightly acidic, then emulsions are less likely to form. You could try adding a little vinegar, although I haven't tried this personally.
I am a NaOH man at the moment and I used some vinegar in the first spray wash in my last batch, don't really know if it helped or not.

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Now why I think this was not helping me in my processing is that in the past I would pump straight into the washtank and imediately do 2 spray washes and 2 bubble washes and all done. The bio was not that soapy but this stuff is soapy as and takes 2 to 3 times more washing to get the wash water clear. But after all that is done it is as good as all the bio I made in the past.

I will be making more this weekend without the prewash and I will also start letting it settle in the washtank more as I can see that to be a benefit.
So you use KOH I would have thought that there wouldn't be a need for this prewashing as I thought one of the main reasons was to keep the glycerol liquid. That is why I was doing it anyway...

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

Re: water washing

Hi HDJ80,

Let us know how your next batch of non pre-wash BD goes.

The pre wash should not increase the amount of soap, quite the contrary. Maybe you are using too much NaOH, do you titrate each batch? Perhaps your last two batches of WVO have been better than you thought .

The way I understand it, the residual methanol suspended in the BD after the initial reaction, acts as a co-solvent between the byproducts and the BD.

The methanol and soaps readily dissolve in water, so by adding water as a pre-wash, the methanol and soaps preferentially attach to the water, releasing the BD. Others may wish to expand on my simplified explanation.
The pre-wash water then sinks to the bottom with the rest of the by- products. This separation appears faster than the non pre-wash.

Any amount of settling time is going to help. I have started washing straight from the processor but I noticed more of the DWS (Dreaded White Stuff). If you let it settle in the wash tank for 24 hours, then drain a little out, I'll bet you'll see some glycerine.

I don't think KOH has any advantages over the amount of soap formation compared with NaOH, it's more about getting the quantities accurate for either. KOH dissolves much quicker in meth, seems more tolerant of WVO quality and water content, and of course makes liquid by-product which is easier to handle.