Centrifuging Biodiesel

[dgs]

As some of you may know I have been centrifuging my biodiesel for a couple of months.
I bought a used Dieselcraft oc20 centrifuge off ebay and although it does 'catch' some glycerol I have always felt that I am loosing some efficiency because I can only get the pressure up to 60psi and this is if I increase the voltage to the Peugeot pas pump to @ 18 volts via a charger. At this voltage the pump starts to smell a little and so I often just leave it on a battery.
This, of course then lowers the pressure even more and makes the whole set up less efficient again.

Whilst I was pondering the whole thing I was scanning ebay and saw this monster advertised;

                                         http://www.ebay.co.uk/itm/262013096979?_trksid=p2060353.m1438.l2648&ssPageName=STRK%3AMEBIDX%3AIT

I duly bidded on it and won the thing for £112.00

I think one of the reasons some others were put off is that at the bottom of the add there is a link to the distributors site. There is also a pump which it says is the one to drive the fuge, the price is £630!!

Anyway, I've bought a piusi viscomat gear pump which is more than sufficient to drive the fuge.

At present I am just setting the thing up so I will report when I give it it's first run.

[Manfred]

Must say that I fancy a centrifuge but the cost puts me off a bit. Appart from glycerol what can be removed. I've read that soap can't then I read that it can. Either way you've got sub micron filtered bio.

[dgs]

Hi Manfred,
Anything that is free or suspended can be removed. Anything that is dissolved it will not remove. I suppose as long as there is no methanol present then any glycerol or soap in theory has to be in suspension, so it can be removed. When I centrifuged a batch of just settled bio the soap level dropped from something like 45ppm to 20ppm after centrifuging.

With this new set up as long as I can keep the pressure between 90 and 95psi the fuge will spin at 8000rpm creating a G force at the outside of the bowl of 4500.

Although soap and glycerine are different compounds as far as we are concerned they are 'as one' in glycerol and when methanol is removed from biodiesel they drop 'as one'. From tests I have done with 'cracking' glycerol it contains around the 45% soap level.

[Jamesrl]

Must say that I fancy a centrifuge but the cost puts me off a bit. Appart from glycerol what can be removed. I've read that soap can't then I read that it can. Either way you've got sub micron filtered bio.

I'm back from me 6 week holidays with the grandchildren so I'll be back on the fuge project.

It'll be 200mm id producing 9000+ G at 2840rpm (a standard 240v motor speed).

The major advantage with the Bowl type fuge is the total control you have over the product flow rate thus dwell time.

I have one of the pump driven fuges but don't use it because of the noise and the faffing around you have to do with'm, you can't see if the bowl needs emptying and the g force vastly reduces as it fills, not impressed with'm for bio use.

[Julian]

Welcome back I thought it had been nice and quiet!

You can't really see if a bowl type needs emptying ...



The colour change is very subtle and by the time you realise it's changed, it's probably too late, crud will have overflowed the bowl (above is a test I did with oil).

With finished bio it may be different, as so little crud will collect in the bowl, you'll probably be able to run a large batch before it needs emptying.

[Jamesrl]

Having seen the colour difference between the crap collected and the bio itself I was rather hoping that the clarity of the bio would allow me to see the build up of crud in the bowl, of course I could be disappointed by the results but never mind I'm still gonna build one.

So there with brass nobs on, la la la ha ha ha.

PS, I bet you've all missed me.

[Manfred]

 What about this one for a diy.

 https://m.youtube.com/watch?v=gKQK5cYin2Q

[dgs]

I missed you Jim.

Manfred, yes- well done to him, building the whole thing out of wood.

Well, I ran the thing today. Slightly disappointed by the top pressure of 75psi with the by-pass valve shut. It certainly turns at some speed, however there is a problem. At pressures over 50psi a loud vibration starts, it sounds like a metal to metal noise internally.

I have taken it apart and checked everything a few times but the noise is still there. It almost sounds as if the bowl is bouncing up and down, but I don't see how this could be. Any ideas anyone.

[Julian]

I missed you Jim.

Don't encourage him, or he'll be annoying everyone even more frequently!

Re. the centrifuge, I've never played with one of that type before but is there a section or drawing in a manual you could post up?

[Manfred]

What is it like if you spin it by hand and can you lift the spinner up maybe causing it to inter fear with the cap when in working mode ?

[Manfred]

Julian. Is the bottle of oil a before or after shot to show that crud can get through if you miss it ?

 Jim. I missed you as well. Honest really, I did. Now where's my Asprin.

[Julian]

Julian. Is the bottle of oil a before or after shot to show that crud can get through if you miss it ?

Strangely both!

If I remember correctly, I put some grotty, fatty, wet oil through and recovered some quite respectable clean oil.  I didn't empty the bowl soon enough though and the crud spilled over contaminating the good oil.

The spilled crud obviously hit the side of the body with some force because it "homogenised" itself with a some good oil ... that's what's in the jar.  It's also what's in the bowl, but the clean oil has separated forming the visible vertical wall the crud is behind on the inside of the bowl.

[Julian]

This is a shot of the "homoginised" crud before and after centrifuging ...





And this is the crud, fat and water left in the bowl ...

[dgs]

I tried to post a drawing from the Bell Flow Systems site but it seems they don't sell this centrifuge anymore.

The sticker on the centrifuge cover is from a company called Stationary Engine Parts. Strangly enough they are based in Elvington near York. I will phone them on Monday.

Manfred, when I spin the bowl it spins ok, no interference at all. When the cover is in place and screwed down there is quite a lot of up and down movement with the bowl, noticeable when it is turned upside down, then turned upright again, the bowl clunks as it moves up and down. I'm sure there should be some movement on it but it seems a lot.

When it starts it's vibrating noise it is very loud, in fact worrying as if something is about to fracture.

[Manfred]

This is a shot of the "homoginised" crud before and after centrifuging ...





And this is the crud, fat and water left in the bowl ...

 Goes to show that if you want to fudge oil a drum is the way to go as a pressure type needs about  100 um filtered oil first. Just keep an eye on it when filtering cruddy oil. Might be useful to Ged if he wanted to spend the money on one instead of sock filters.