Water washing and titrated soap tests.

[nigelb]

It is quite clear that in the past few weeks I've upset some people with the way I defend and promote my water washing methods. For that I make no appologies.

What I've been trying to do is to inform and educate biodiesel producers as to the ease of water washing without the intervention of unnecessary chemicals.

Don't get me wrong..I'm not against experimentation dispite the comments of some on both this and the VOD forums.

Following comments made by Mark regarding the unusual figures gained through soap testing during acid water washing I made a statement on this thread...http://www.biopowered.co.uk/forum/index.php/topic,966.msg986... saying that I'd do a soap test after each wash on my next batch. I've stated many times that I typically do 4 washes to complete a 150lt batch.

As I'm not on a meter I use standard  tap water, but ,due to bleating on the VOD by senior members over the years about wasting valuable resorces, I have used, in the past, water harvested from the roof of my shed that is stored in a water butt. That argument does not stack up and should not be used by anyone arguing or discussing the merits of water washing.

So..this Friday (22.2.13) I made a 150lt batch of fuel using the two stage no titration method. I dried my fuel using 13lts of dry glyc from the previous batch and used 18lts of methanol and 3.0lts of ASM for stage 1 and 0.5lt of ASM and 3.5lts of methanol for stage 2. This resulted in a perfect 5/45. No dropout...no haziness just a clear solution when the bio was added to the methanol.

What was I expecting when I started the testing?

I expect that the soap levels would be lowered following each water wash....but would my claims of water washing be backed up by scientific testing?

I took a sample to be tested from the raw biodiesel just after it had been transfered to the wash tank but before any water was added.

Before washing:

4.4ml of 0.01N HCl = 1337.6ppm of soap.

After 6 hours of gentle washing the first lot of water was drained from the tank, a sample of bio was taken from the top and was tested for soap.

1.35ml of 0.01N HCl = 410.5ppm of soap

Following an overnight wash (16.00 Sat to 07.30 Sun) wash 2 was drained. The water looked very soapy and I skimmed some soap from the top of the bio. While prepping some more water I turned up the air supply to allow any remaining soaps to be distibuted evenly throughout the solution before a sample was taken to be tested.

0.25ml of 0.01N HCl = 76ppm of soap

Dispite its low value of soap ppm's the bio did not look like it was close to being finished.

The third 10lt of water was added at 07.30 and was bubbled until 12.00. When the water was drained the bio looked much closer to being finished and a test was conducted.

0.15ml of 0.01N HCl = 45.6ppm of soap

I then heated the fuel to 55°C and added 10lts of hot water. I then put on the lid of the wash tank and turned on my central heating pump and pump washed for about an hour. The water was drained and a sample taken from the top following a period of aggitation to guarantee an evenness of soap throughout the solution. A titration test showed:

0.05ml of 0.01N HCl = 15.2ppm pf soap.

I have to admit that I've never tested like this before ie titrated soap tests at each wash. The results are pretty good and back up the claims I've made over the years.

Conclusion:
4 washes (40lts)
soap reductions from 1337.6ppm to 15.2ppm
wash period: 10:00 Sat - 16:00 Sun. (now drying)


Nige

[Head Womble]

Very interesting Nige, it's backed up my thoughts on the acid wash messing with titrated soap test results.

Until now I've had nothing to cross reference against, and had no idea what soap levels raw bio would typically contain.

To give you an idea of what I mean, these are the results I got
124.64ppm after the acid wash,
54.72ppm after wash 1
94.24 after wash 2.
Wash No3 tested at 59.24

[Head Womble]

Compairing Nigel's results to mine it suggests that the acid may get washed out by the second wash.

[Julian]

Good set of results.

Not dismissing your results, Mark, but what would be interesting would be for Nige to try other methods on soap removal with his plant, process and chemicals and record soap ppm at similar stages or frequency.  That should give quite a good comparison of the efficacy of each method.

Would make quite a nice wiki page ... you up for it Nige?

[Jamesrl]

Conclusion:
4 washes (40lts)
soap reductions from 1337.6ppm to 15.2ppm
wash period: 10:00 Sat - 16:00 Sun. (now drying)


Nige

Totally vindicated Nige, that proves Acid/Acetone washing is NOT required for the average home brewer.

I tried it and didn't get on with it at all, never again or until I've set up for your gentle wash method.

[jgs600]

nice write up there nige, interesting to see how long you bubble for, i guess by you using 4 x lots of water isnt to disimilar to me using 4 lots of water but pump washing instead of bubble washing which is more aggresive, may i ask once you have finished bubble washing do you tend to lose a small amount of bio in the water wash, as i tend to start with 100litres of bio and end up with about 95litres...
cheers
glenn

[1958steveflying]

Conclusion:
4 washes (40lts)
soap reductions from 1337.6ppm to 15.2ppm
wash period: 10:00 Sat - 16:00 Sun. (now drying)


Nige

I tried it and didn't get on with it at all, never again or until I've set up for your gentle wash method.

Perhaps if Nige were to quantify his gentle bubble wash method others that have an interest may reproduce it.

IE: What air volume ? pumped through what stone/bubble device at what level in the Bio.

I was surprised to see that you pump washed the 4th though !

[nigelb]

Thanks for your comments gents. Some interesting points raised and questions asked.

I'll address your points first Steve. The volume of air cannot be acccurately gauged or even guessed at. I use a Hailea pump..I think it's a 75lt/min version but it's controlled by an aquarium control valve so hardly ever pumps at full tilt. I use a 50mm cylindrical ceramic air stone that sits on the bottom of the wash tank. The 4th wash is the hot wash and ever since installing this set up have always pump washed the last cycle. It has always guaranteed the soap levels drop that little bit further due to the emulsion the water and bio form. It's a bit like a huge 50/50 shake-em-up test.
As a side point and something I mentioned to Mark in another thread, I recorded, on my lads xacti, my wash tank with all its components and an example of what gentle washing should be and also an example of washing that is likely to cause an emulsion. My lad and I still have to edit that footage. As soon as we do, it'll be on his utube channel and I'll post a link.

Glenn...I hardly lose any fuel in my washing. With gentle agitation there is less likely hood of an emulsive layer...resulting in a clear division of where the water stops and the bio starts.

Julian...in the interests of comparrison I'll give some of the other methods a go...would you message me as to what you want me to do.

Nige

[Head Womble]

Nige, it's quie easy to messure the volume of air being pumped,
hold an inverted (but full of bio) cylinder of a known volume above the air stone,
and time how long it takes to displace the bio with air,
you can then calculate the lpm of air flow.

Yes I know it's going to be a bit messy, but it's all in the name of science.

[Julian]

Settling would be dead easy to do and could be done two ways ... with and without 7% prewash.

Without 7%
Finish the batch as normal, pump out to your wash tank, bubble overnight to demeth (no water) and simply leave for the soap to settle, testing for soap with a similar frequency as your first test.

With 7%
Process as normal but before draining glycerine, add 7% water and pump for 15 - 20 mins.  Settle and drain glycerine, then as above.

See how those go then maybe try an acid wash.


Marks idea for checking flow is probably better, but you can measure flow with a variable area flowmeter or rotameter, you get similar things on professional mig sets I think.  A company call CT Platen made the ones I played with in a former life.  I've been looking for a small instrument for years to measure flow round the vapour circuit.

This type of thing ...

[Jamesrl]

I've been looking for a small instrument for years.

Tried looking in y'pants?

[Julian]

I've been looking for a small instrument for years.

Tried looking in y'pants?

Commando me.

[Jamesrl]

I've been looking for a small instrument for years.

Tried looking in y'pants?

Commando me.

Wow! That's brave of you looking in a Commando's pants, did he know?

[Tony]

Marks idea for checking flow is probably better, but you can measure flow with a variable area flowmeter or rotameter, you get similar things on professional mig sets I think.  A company call CT Platen made the ones I played with in a former life.  I've been looking for a small instrument for years to measure flow round the vapour circuit.

This type of thing ...

Are they glass inside?

I've got a flow meter on my Argon bottle regulator (not the dial type) but the internals are all plastic pipe, which would be pretty poor with Methanol vapour.  I guess it would be best after the condenser but all the same.

It would be nice to know the gas flow rate, that's for sure.

And sorry for crashing the water washing thread with talk of condensers

[Julian]

They vary in my experience.  I have a couple which are uncalibrated and operate as flow switches via a reed switch.  They are far too large for the venturi application but they have glass bodies.