In processor titrated water wash method

[Islebio]

Hi,

I have been following this post and trying this method for the last 4 or so batches. I have been getting a good 45/5 test result, i have had little luck with the figuring out how much acid i need, so have been adding 5 litres of vinegar to a batch of 180 litres bio. I then start adding the water and it always turn to some form of emulsion. I wash it about 3 times till the waste water is clear, then dry the bio in my drier (sprayed out at heat), this takes all ( or most)of the water out. It still remains a bit cloudy but passes the 50/50 water test really good with little soap.

Questions - should the bio be totally clear after adding the first batch of water wash
 - Why when you do a 50/50 shake test on soapy bio and it settles out really nicely to the bio at the top, soap in the middle and water at the bottom, does this not apply to the bio in the processor? I thought i could just drain it alll off ( i left it over a week )

Any help appreciated.

[dgs]

I just love these old threads being brought into life again. Islebio, I am not a great lover of this method (as I have posted before)

If the amount of acid needed is small then granted, there can be some advantages as regards separation of water and bio, but adding lots of acid or in your case vinegar is a no no.

Your soap level after the last reaction when you have achieved a good 45/5 could be 000's of ppm's and with the acid addition you will turn these soaps to free fatty acids. In addition you will have monoglycerides present (they are always present no matter who's bio it is) Water washing can be a good way to remove these but the addition of acid encourages them to stay in the bio.

Before you add acid, water wash with water only. Mist or gently bubble if you tend to get an emulsion, or better still either de-meth (if you don't already) or do a 5% pre-wash with water.

http://www.biopowered.co.uk/wiki/Water_prewash

[dgs]

Just to qualify a few things with my post.

first Islebio to answer your questions. No, the bio should not be clear after the first water wash as it will be saturated with water (something like 1000ppm)

The mix in the processor should roughly follow what has happened in your 50/50 jar, but if the relative temperatures are different (if for instance you have brought the test into the house) then this may account for the two being slightly different.

It is my opinion that biodiesel with amounts of FFA's and Mono's left in the mix is more viscous than biodiesel without these contaminants. Furthermore I believe that biodiesel with these contaminants is less volatile than without them. Both are reasons to remove/not produce them if using the fuel in a common rail vehicle.

If I ever do use acid the soap level is <100ppm and then I only use 5mls of 50% acetic in 8 litres of water. This is with a 200 litre batch size.

[Islebio]

Hi DGS,

Thanks for your help, i am really trying to do this to avoid waterwashing. I have a jamesrl processor where i demeth via the condenser till there is nothing dripping out ( last time i did this i think i may have left it too long as the liquid coming out was eventually brown). I then transfer this to a bubbling tank and leave to bubble for about 12 hours, i then heat up again in that tank before i leave to settle. Even though i do this the 50/50 sample seems really soapy. I know that water washing via misting will reduce this soap but i'm just trying to do a quicker turnaround on the process.

Cheers

[dgs]

if you are just leaving it to settle after demething then the catalyst used will make a great difference to the soap level. If you are using Potassium then even after demething the soap could still be quite high in which case filtering through oak chips is a good idea, it should bring the soap down to zero.

[Islebio]

Hi,

Yes i do use potasium, I do have a dry media tower, which i fill with ecopure2 media and change every 1000 litres then through a 10 and 5 micron filters but still seem to have a soap content, haven't tried the resin tower but this may be the next move!

Cheers

[dgs]

A soap test kit is a good idea, then you know exactly whats what. They are very easy to use and very accurate. The 50/50 is only accurate to a point. NigelB on here sells them.

If you use ion exchange resin the life expectancy is greatly reduced if the starting soap level is greater than 500ppm.