Alternative fuels > Waste Vegetable Oil

WVO Centrifuge Design - thoughs ?

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--- Quote from: EdDee on June 18, 2018, 03:18:13 PM ---Hi V,

While it will certainly clean the vast bulk of the debris, I, personally, am going a slightly different route in the bits I am getting together... I will be using a "fill tank" to dribble the oil through the fuge first time round to collect most of the junk... thereafter it will be a single tank system which will recirculate until shut down...

--- End quote ---

Hi Ed,

In a similar fashion, my raw oil will pass through a fine screen on the way into the single tank.
Everything else should get trapped by the centrifuge when subjected to 3000 G's (5000 rpm).

Based on the input from you fellas, I will proceed with a single tank system and see how it works out.



Whilst I do not intend to run waste motor oil, there are many that do. Your centrifuge system should be a big help.
Here's what some are removing from their WMO...

keep us posted...

I started to make my own bowl using an old car brake drum... but I'm wondering if I shouldn't machine up an aluminium one from scratch... I'm concerned that the brake drum may not have enough strength to stay together at the sort of speeds I'm planning to rotate it.

Can I ask you a favour Veggie - how much does your bowl weigh, with lid? That's something else I'm contending with... the weight of the cast iron brake drum + a steel lid, might be a bit excessive...


--- Quote from: AdeV on June 19, 2018, 08:19:04 AM ---Can I ask you a favour Veggie - how much does your bowl weigh, with lid? That's something else I'm contending with... the weight of the cast iron brake drum + a steel lid, might be a bit excessive...

--- End quote ---

Hi AdeV, the spinning bowl does not have a lid.
Oil overflows the bowl and is caught in the outer chamber.
The bow weighs about 5 lbs.
I got it here...
It comes with a special taper lock hub which anchors it to a 5/8 shaft.

Hi Glort,
Fortunately the oil I get has very little water. (I trained them well  ;) )
However...there is always some water and my experience is that these types of centrifuges do a pretty good job of dewatering if the oil is hot enough.
In this example (not mine) you can see the steam leaving the processed oil ( at the 1:00 minute mark ).
My unit has vapour ports in the lid and in the discharge line to channel moisture out.
1st generation fuges spin at 3600 rpm motor speed but with the use of 3 phase motors and variable frequency drives newer fuges can now run up to 6000 rpm making over 4000 g's. That really takes advantage of the sight specific gravity differences between water and oil. My thoughts are that multiple passes should eventually leave the oil quite dry, but until I run it ...I won't know for sure.



--- Quote from: glort on June 19, 2018, 11:50:11 AM ---
Not so much the weight you have to worry about Ade, it's the balance.


For a brake drum you could work out the rotational RPM at say 100 MPH and then spin the thing equivalent of say 150 with safety.  As long as the drum is in good Nick to start with and balanced, you should have no problems.

--- End quote ---

Balance - agreed... and I have no way to balance it other than statically, which is almost certainly not good enough... However.. my unit will be nowhere near 25l in capacity; that must have been a bloody monster of a machine!

I reckon the capacity of my brake drum, by the time you've added the centre spigot & lid, will be around 1.5-2 litres tops. It's about a foot/30cm across, if I recall correctly, and about 5"/12cm deep. I'd like to spin it as fast as humanly possible...

Assuming it used to live inside a 13" wheel (which seems about right, given its age), that would have had a 4 or 5" sidewall tyre fitted, so about 23" total rotational size, which is about 72" circumference (handy), or 6ft.

100mph is 8,800ft/min, so the brake drum is doing 1470rpm just about. So your safety margin gives me 2200rpm. I was hoping for at least 3600, and maybe even higher...

Next up - work out how many g's that is. That's beyond me tonight... I'll have a go tomorrow.

Anyway, as I wouldn't trust it not to explode at very high speeds, I intend to wrap it in a 5mm thick steel enclosure. I guess I should be able to calculate the centrifugal forces on the side of the bowl at a given RPM, then assume a 1lb lump flies off I can calculate the energy in that when it strikes the outer casing, which will tell me if I need to put a second 5mm steel ring around the inner one for protection purposes... although I might just do that anyway. Steel is a LOT cheaper than internal organs, and a damn site easier to replace...


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