Green coloured bio

[paulp]

Hello,
I have had a strange experience.
Recently we have been having issues with soap emulsions.
Our process is heat and cool to gt oil dry,glyc wash to dry, 2 stage no titration, 7% water glyc wash then transfer to water wash.

The last batch produced a particularly difficult emulsion to crack.
We used vinegar and glyc washes to crack it.

At the end of the washing the bio turned green.

I thought maybe the acid has got at the copper pipes.

The soap level is 48ppm, using nigels soap test kit, but I am afraid the effect on my car.
Its clear but just green....

Anyone got experience or thoughts if its safe for my car and why it maybe happened.

[Julian]

Welcome to the wiki and forum.

Soap generation can only happen in the presence of water, so first off I'd look at your drying process.

What temperature are you taking the oil to in your drying process?

Do you have a venturi and condenser?  If so taking the oil to 85 - 90°C and using the condenser is probably the most effective and foolproof way of drying it.

I have a copper tank and pipe work and pump wash using concentrated sulfuric acid.  The only time I see green contamination is when oil or the remnants of a batch are drained from the processor.  I've never had a green batch as such. 

The best way of sorting out problems like this is to go back to basics ...

Dry the oil as described above (if you have the facilities), don't glycerin wash, do a two stage with titration and demeth if you have the facilities, then do 7% water wash with the glycerin from the process and see where you are at the end of processing with a 3/27 and a "Nige test".

If it's not too soapy try simply settling over time.

What washing options/facilities do you have?

[willbuild]

I had a batch that had a green tint to it. The wvo was also green, came from a Chinese take away.
was perfectly good to use.

[paulp]

My source oil was a mixture of whites oil and solid fat. It all started out life the correct color but it didn't turn green until the final washing and drying stage.
In our drying process wee take the oil to 60c. This is repeated a few times. Heat and cool.

We have a three tank  gl setup with a venturi and condensor. We don't use the condenser we rely on the glyc wash and heating and cooling in tank 1. We were a bit nervous about using the higher temperatures initially so we have stuck with 60c throughout.

I will take your advice and use the condenser to ensure the oil is dry taking it up to 85ish.
Is there a way to measure the water content of oil. The hot pan test is pretty subjective.
I think I will try this first then change step by step.

The green tinge had to be something to do with copper I am guessing. Any thoughts?

[Julian]

It sounds like it's the drying process that's causing you the problem compounded by the quality of oil.  The feed stock you describe will need to be very heavily dewatered, probably at higher temperatures than 85°C.  60°C isn't nearly hot enough to get shot of water in good oil.  Don't worry about taking the processor to high temperatures unless you have plastic in the system ... if you have replace it! 

I don't glycerin wash myself, but I would view this as a final "polishing" process of the oil or a possible means of recovering some of the chemicals from the glycerin.

Run the condenser until water stops dripping.  If you have a SHHE a good indication of dry oil is when the pipe between that and the condenser starts to run cool.

You're right HPT isn't quantitative, but it's a good indication that the moisture content is low.  KH designed a water in oil test based on the Sandy Brae principal ... http://www.biopowered.co.uk/wiki/Water_in_fuel_-_test_kit

It may well be that my heater element is covered in crud and assisting process, but when I turn it on immersed in wet oil you can hear popping and crackling from inside the processor.  Switching it on to reheat dry oil it's completely silent ... a sort of in tank HPT and quite reassuring!