7% Post Reaction Soap testing

[nigelb]

Following the testing for soaps on last weeks batch I thought I'd back up the testing and claims with the testing of this weeks as well. These results have now been published on the thread. http://www.biopowered.co.uk/forum/index.php/topic,995.0/topicseen.html

With a slight difference or addition to the testing I made attempts to quantify the claim that a post reaction wash of 7% water dramatically reduces the soap content of raw biodiesel. I figured that if a titrated value could be found and backed up with some real data...something I've not seen recorded anywhere..then it could have real benefits for the natural progression of this method. We all know it works...but to what extent.

However, the testing was less than successful with little or no colour change from the test sample. I suspect that the amount of 0.01N HCl used got in the way. It got to the point where I had injected 10ml of titrant and the solution started to take on a cloudy appearance having emulsified slightly with the sample and the IPA. I made two attempts to titrate but was met with the same issue on both occasions. Too much soap!

It makes me wonder whether a stronger version of titrant would help and then use a multiplying factor to give a ppm value. I can get my hands on some 0.5N HCl from work but I suspect this may be too strong. Or could I get away using a smaller sample of bio???

I've retained a sample of bio prior to the "prewash" so I've got something to play with.

Your thoughts please.

[Jamesrl]

I had the same problem trying to quantify the soap PPM on raw bio, just too high.

[nigelb]

How much titrant did you add before you realised it wasn't going to work?

[Jamesrl]

Can't remember exactly but at least 1/2 of one of your little bottles.

[nigelb]

Do you want some more....FOC

[Jamesrl]

Do you want some more....FOC

I'm ok for it atm but thanks anyway.

[nigelb]

I've just done a quick experiment with results that will need backing up the next time I make fuel.

Because I was unable to get a titrated soap test result on raw bio that has not been prewashed using conventional methods I decided to reduce the sample size to 10% of normal. Normal being 12ml.

1.2ml of untreated raw bio took 4.25ml of 0.01N HCl to change the colour to yellow.

(4.25 x 10) x 304 = 12,920ppm

A test of bio taken after the 7% post reaction wash with this fuel was 851.2ppm.  A huge reduction


Could those who have test kits please undertake some testing when you next make fuel and post up when you have results. Thankyou

If this is right then the benefit of a 7% post reaction wash can finally be quantified with figures. As stated in my OP...we know it works but to what extent.

Nige

[Jamesrl]

So a 7% pre-wash removes 93.5% of the soap in the Bio, WOW!

[nigelb]

So a 7% pre-wash removes 93.5% of the soap in the Bio, WOW!

It needs more data to back up the initial test. I'm making no claims yet...just posting what I've foundso far. If it's correct it truly is a WOW moment.

[Head Womble]

That is a hell of a reduction,
these findings make me it a hard decision, do we use the (dry) gly for prewashing or forget the gly prewash and go for post reaction 7% prewash.

I'm sure the 7% prewash is key to your water washing success, as far as I know you're the only one that does this in conjunction with water washing, it's normally only settlers that do the 7% thing.

[nigelb]

I glyc wash and 7% prewash.

Of the glyc drained down from stage one of the no tit process (18lts or so) just 4lts gets reintroduced to the reactor prior to the 7% water wash. This is to prevent the chance of any emulsion and is being reduced batch on batch. I used to pump 5lts back in.

This method means I have about 14lts of dry glyc for glyc weashing and an amount of glyc to prevent an initial emulsion when prewashing.

Best of both worlds.

I surely cant be the only water washer who has a 7% prewash as part of the process.

Don't get carried away with the initial ppm results Mark...It requires further testing before any claims can be made.

[Head Womble]

Great idea that Nige, obviously works for you.

I've not heard of another water washer do a 7% wash, allthough it is a common practice for demeth and settle.

I'll put a post on here and VOD to find out if others are doing it.

[theraw]

I think I experience the same sort of drop in post-reaction soap levels but by a different process.

I'm a recent convert to water washing due to the good results from the titrated acid wash method. My process is glyc wash, 2 stage no-titration and then I always bubble demethed.

On my first batch with water washing I didn't bother with the bubble demeth reasoning that the water washing will remove the remaining suspended glyc and methanol in the raw biodiesel. I also like to know what's going on with each batch so I always soap test before and after washing and sometimes inbetween washes.

Anyway, on this batch my pre-water wash soap levels were 4,576ppm (it may actually have been higher as I was taking samples for testing from the top of the reactor but now I make sure they're taken from the bottom). But this led me to have to do the acid wash and 5 water washes to get clean fuel which didn't seem very efficient to me. So on the following batches I reintroduced the bubble demeth stage. This is a no-effort part of the process as when I make a batch of fuel the glyc wash and 2 stage processing are all done in one day but there's never any time left to start washing. The bio is still hot so dropping in the air bubbler and letting it bubble over night allows another 1.5 to 2 litres of glyc to drop out (I do 80 litre batches). On the batch I've recently completed the post-bubble demeth soap level was 896ppm but on a previous batch it was as low as 288ppm! So including the bubble demeth stage means I only need to do the acid wash and 1 water wash to get clean fuel.

So I'd say that some sort of post-reaction process to initially drop the soap levels (whether it's bubble demeth, 7% post reaction wash or something else) is a very beneficial stage and greatly simplifies the water washing.

[1958steveflying]

I've not heard of another water washer do a 7% wash, allthough it is a common practice for demeth and settle.

I'll put a post on here and VOD to find out if others are doing it.

I demeth and settle but never do a 7% water prewash as I use the glyc for oil pre treatment, which includes a partial reaction which I understand it wont do with water in it.

[nigelb]

I made another batch of fuel today and performed a soap test on the raw bio prior to a 7% prewash. The results are:

Using a test sample of 1.2ml and a multiplier of 10 in the final calculation the bio titrated at 2.6ml of HCl. So 2.6 x 10 x 304 = 7904ppm

A sample of fuel taken after the post reaction wash titrated at 3.8ml of HCl. So 3.8 x 304 =1152.2ppm

The only variable this time with the process was the re-introduction of stage 1 glyc following a successful 5/45 and prior to the wash was only 2lts. A reduction of 50% on my last batch. Hopefully this will be reduced further on the next batch.

Perhapes some one could work out the percentage reduction in soaps for me.