Biopowered - vegetable oil and biodiesel forum
Biodiesel => Biodiesel equipment => Topic started by: dgs on September 04, 2015, 08:02:52 PM
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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.
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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.
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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.
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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.
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Welcome back I thought it had been nice and quiet!
You can't really see if a bowl type needs emptying ...
(http://www.palmergroup.co.uk/Bio/centrifuge_resized_3.jpg)
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.
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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.
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What about this one for a diy.
https://m.youtube.com/watch?v=gKQK5cYin2Q
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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.
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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?
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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 ?
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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.
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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.
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This is a shot of the "homoginised" crud before and after centrifuging ...
(http://www.palmergroup.co.uk/Bio/centrifuge_resized_2.jpg)
And this is the crud, fat and water left in the bowl ...
(http://www.palmergroup.co.uk/Bio/centrifuge_resized_4.jpg)
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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.
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This is a shot of the "homoginised" crud before and after centrifuging ...
(http://www.palmergroup.co.uk/Bio/centrifuge_resized_2.jpg)
And this is the crud, fat and water left in the bowl ...
(http://www.palmergroup.co.uk/Bio/centrifuge_resized_4.jpg)
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.
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http://www.bellflowsystems.co.uk/centrifuge-for-biodiesel-bio-diesel-engine-oil-and-waste-vegetable-oil-41
Dave. I can't get the link but it might be my pad acting up.
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Last link goes to their home page and searching their site for centrifuge yeilds no results.
Did a search on Google ... was this what you were after?
(http://www.bellflowsystems.co.uk/files/Lees%20Images/Oil-Path-Diagram.jpg)
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I missed you Jim.
Of course you have, who hasn't!
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.
You need to get 103psi to get max rpm out of the fuge, as for the rattling, yes the bowl will lift at approx 75psi but has it been dynamically balanced or has the balance weight dropped off?
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... yes the bowl will lift at approx 75psi ...
Just been looking at the drawing before you posted and was wondering if in fact the rotor moves vertically at all?
If it moves up (or down) it will need some sort of thrust bearing to take the force ... is there one? I can't see from the detail on the drawing and you've obviously pulled one apart.
From the drawing it would appear that the rotor should be sealed to to the shaft otherwise dirty oil would escape into the clean areas.
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The weight is intact Jim and the positioning arrows are exactly in line. When you say the bowl will lift at 75psi is this meant to happen.
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I think the internal pressure acting between the shaft and rotor tube gives it low friction like a fluid bearing principle.
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The weight is intact Jim and the positioning arrows are exactly in line. When you say the bowl will lift at 75psi is this meant to happen.
There has to be a little vertical clearance to allow expansion of the bowl, don't forget these fuges are designed to filter hot engine oil not cold bio.
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My guess (based on the drawing) is that the whole thing won't operate below a certain pressure. There's what they term a "check valve" impeding the flow which must open at a specific pressure. I struggling to see why that fitted to be honest. It may be something to do with being fitted to operating engines which require a pressure in the rest of the system as a priority over running the centrifuge.
Dave, you could try running it without the spring and valve disk? You may well get more flow that way. Any pressures you are currently measuring will be of that valve and have little to do with the rotor assembly.
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Don't think I can Julian. I think the valve is a safety feature, if the pressure is too high it pushes the valve against the spring and lets the bio bleed through a hole without going into the fuge.
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Ah, cant see that on the drawing. So as a safety measure it dumps dirty oil into the clean oil?
If there's no signs of mechanical contact on the moving parts, could the over pressure part of that valve blowing off be the source of you're noise?
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I have considered that and it is possible. If for some reason the spring isn't strong enough the valve could be bouncing off it's seat. However the other thing I have noticed is when it is decelerating from whatever rpm it is doing at 50psi (it is still spinning at a high speed even at this lower pressure and takes around 25 seconds to stop) it goes through another vibration phase (very loud) as it is slowing.
When I phone them up tomorrow as they are only 9 miles away, with a bit of luck if I speak to someone who is helpful and considerate? they may even come out to have a look.
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there's a chance there's nothing wrong with it and there's just some odd harmonics/vibration at certain rpm - it doing it again when it's slowing down suggests it might be this...
if you can get it to go faster you might push past the vibration so a spot where it's smooth again
it's a bit like when you have a tyre on your car that isn't balanced very well... it can be fine up to 60mph, start to vibrate, but then by 70 it's smooth again :-)
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Thanks Knightly, yes it is possible.
I have a bio friend coming to see me today, he wants to see it working, I'll wait until he's here and 'give it the gun'
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If you're really serious about getting your fuel clean, check out purifiers or as they're sometimes called, separators. Alfa laval and Westfalia are the two major manufacturers. I posted some photos of a strip down on here a while back.
https://www.google.com/search?q=alfa+laval+purifier (https://www.google.com/search?q=alfa+laval+purifier)
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They look superb things but arn't they very expensive.
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Ran it up again this afternoon, same thing. It really does sound like an internal metal to metal noise.
Centrifuge spec, at 90psi flow is 7lpm.
Pump spec, flow 9lpm, max pressure 180psi (12 bar)
Can't get the pressure above 75psi. I wonder if it's because it's bio and not oil.
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My pump has an adjustable pressure bypass, maybe yours has.
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Yes it has Jim and it looks to be screwed all the way in, should I unscrew it to try.
I think I have sorted out the fuge problem, will post later when I have more time (will take a little explaining)
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any idea what flow rate you're getting ?
can you catch some in a bucket and check ?
most gear pumps have a very flat pressure/flow curve
it's it's 9litres/min max pump, and the fuge is letting 9litres/min through it then they'll be naff all back pressure against the pump
it's like sticking your finger on the end of a hose pipe... you can move your finger around and change the pressure and how the water squirts out, but you still get practically the came amount of water through the pipe and out the end ?
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Don't know Knightly, I'll have to check.
Fuge is rated at 7lpm at 90psi.
Pump is rated at 9lpm 12bar max (180psi)
With those figures I would have thought it should easily get the fuge up to 90psi but 70 it is!
I phoned stationary engines this morning who told me they don't sell centrifuges any more and haven't done for 2 years.
So, went into the bio room and had a ponder. Got hold of the fuge and tipped it upside down to slide the bowl up and down on the shaft. I did the same with the old fuge and found the bowl on the new one had a massive amount of float on it, probably 3 to 4 mms.
I've been told that overtightening the nut at the top of the bowl that holds the whole assembly together can lead to distortion so it should only be hand tight (even though it has 2x spanner flats on it!)
overtightening can lead to distortion apparantly and 'squashes' the bowl giving rise to end float.
With this in mind I placed a washer on the shaft before putting the cover on and ran the thing up and noticed the vibration noise was less. I then put 3x washers on the shaft and it improved again.
I then made a silicone 3mm washer for the shaft top and ran it again. Result was a near perfect run! I will have to do a little more adjusting but that seems to have sorted the problem out. So has the bowl been distorted by someone tightening the nut with a spanner- anyones guess.
All I have to do now is get to the bottom of this low pressure thing.
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Spoke to Commercial Fuel Solutions today (suppliers of the pump) and they can't understand why the fuge won't pressureise to more than 70psi.
They said that they would get someone in the technical department at Piusi to phone me. No one phoned.
Jim, I checked the by-pass and it's screwed all the way in, if I unscrew it the pressure reduces. I am sure if I was pumping hot oil the pressure would be higher. Probably all the people I've spoken to don't realise some of us fuge bio.
I'll speak to the pump people again tomorrow and be a little more direct with them. After all they did confirm the pump would be more than adequate for the job.
It looks to me as if this is what I should be using.
http://www.commercialfuelsolutions.co.uk/piusi_viscomat_electric_oil_transfer_pump.html
Model 230/3m
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This is my pump Dave, not sure what make it is as the terminal box and fan cowling were smashed when I acquired it.
I printed new parts for it and 7bar doesn't bother it.
(http://i262.photobucket.com/albums/ii82/jamesrl47/Mobile%20Uploads/20150504_204810_zpsa83gjpmz.jpg)
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Spoke to Commercial Fuel Solutions today (suppliers of the pump) and they can't understand why the fuge won't pressureise to more than 70psi.
Am I right in thinking that these fuges use a small turbine wheel and a nozzle for rotation?
If so, then the significantly lower viscosity of bio won't generate the same pressure against the nozzle as with lube oil. You'll need to run the pump faster, or use two in parallel. Or use a small nozzle - but then that might not match with the turbine - maybe.
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That is something I have considered, using smaller jets but I don't know if they are available. I've considered using the jets out of the smaller centrifuge if they would fit but as you say they will not match the centrifuge. The easiest way is to use a stronger pump.
Even at 70 psi the thing is really turning at some speed but when I'm using it on bio my thoughts are in order to extract any remaining sub micron glycerol I need to get every ounce of efficiency out of it.
Until I get the pump situation sorted, probably tomorrow I will centrifuge the whole batch with soap tests before and after just to try and see what is happening.
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can you put some cold oil through it to see what sort of pressure that runs at ?
and/or
you could fuge your bio, clean the bowl out, and then fuge it again... if the bowl is clean after the 2nd pass then the 1st pass cleaned the oil perfectly and you don't need any more pressure anyway ?
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Rational Thinking, Knightly.
I've just done a similar thing. Soap tested some partially settled bio, fuged it once and tested it again.
Before 83ppm After 70ppm. I wouldn't have thought this was good. Quite a lot of liquid glyc in the bowl, not stuck to sides like the other fuge.
Right, found out the jets are interchangeable. So put the old jets out of the small fuge into the new, larger one and it easily pressurises to 100psi+. Lower rpm at higher pressure with these jets, noticeably smaller hole in them. I think this proves the pump isn't up to the job.
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that's a shame :-(
is the pump new ? any chance they'll take it back ?
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that's a shame :-(
is the pump new ? any chance they'll take it back ?
It is new, and yes they will, but they are not pleased about it. After all they did confirm to me it would suit the fuge. One of the partners blew his top with me, saying he was a 'fluid engineer' and the pump was suited to the fuge. He told me
I should restrict the flow exiting the fuge then I would get more pressure, I told him I couldn't do that. He then got into a frenzy at the other end of the phone. What a strange man, but I kept my cool. I will speak to the other man there tomorrow and see if they are willing to supply me with the more powerful version. I hate situations like this, but I'm learning fast about fuges and pumps.
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What sort of fluid engineer would think that you could restrict the outlet of a fugue to increase its pressure ? Nob.
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Exactly. The saga continues......................
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The replacement pump should be coming mon or tues, so at the moment I can't do any centrifuging.
So just to summarise re the last batch (190 litres)
De-methed with the compressor, then bubbled for 12 hours. all glyc was removed, then settled for 48 hours.
At this point the soap was 83ppm. I then centrifuged it once (with fuge at only 70psi) it did remove quite a bit of glycerol, but as liquid, not as a paste) after fuging the soap reduced to 70ppm.
I then fuged it again with the smaller jets fitted at 100psi and about the same amount of liquid glycerol was removed. the soap level was then 35ppm.
It was then left to settle another 48 hours (couldn't re-fuge because pump returned) and ran off the glycerol in the bottom pipe, there was 12mls.
I've then left it another 48 hours and this morning there was 3mls of glycerol in the bottom pipe and the soap level is down to 15ppm.
Now I don't know how accurate these next figures are but obviously there is a correlation between residual soap and glycerol left in the bio. I suppose at this point we should really call the glycerol (glycerine) as there is no methanol left.
when I have 'cracked' glycerol using concentrated sulphuric I have found that roughly @ 30% of glycerol is soap ( from the amount of ffa layer and titrating the layer) if this is indeed correct then my last soap titration of 15ppm (which I think equates to 3mls in a 200litre batch) means that there is another 9mls of glycerine in there.
I may be 'way off' with my thinking about this relationship, but what is interesting is the en14214 specs re soap and free glycerine. soap (koh derived) 66ppm free glycerine 200ppm.
I will centrifuge the batch again when I get the pump and as long as it gets up to the correct pressure I hope that will result in leaving the glycerine as a paste on the sides of the bowl.
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No accurate measurements Dave, but from my observation of glyc that had been sitting for a long time was roughly a third brown soapy phase and two thirds black phase, and IIRC previous experimenters with glyc contents also arrived at similar third soap.
I think Paul Carrington has some experience of gly cracking but I may be confusing him with someone else.
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Good to know Chug, thanks for that.
I have cracked glycerol a few times, not to recover ffa's but to obtain the 'spent glycerine' as it is void of soap.
I used it to de-soap the bio before water washing, as indeed I did with pure glycerine. However with a bit more experiance and patience I now just de-meth which usually reduces the soap to <100ppm if it is left to settle a while. Then I decide if there is enough time to just let the batch settle or if I should water wash.
I just used to add the sulphuric at 4% to the glycerol in cubies and leave them in the sun. I found separating the layers was a pain. I think a tall, narrow plastic conical is best with a series of taps on it. It needs some heat to be efficient.
When my friend 'Russ' was in business producing bio commercially from glycerol, he had 4x 10000 litre tanks for cracking. he kept the glycerol at 90degs for 12 hours (after de-mething) he used to use 2000 litres of conc sulphuric per week and get his glycerol in 28000 litre tankers. A big set up but economics caused him to close.
he built a still for the bio, it was nearly like water to look at, it used 80k/w of heat!
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Didn't Jules indulge in that for a while?
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I'm sure he did, the ffa layer makes good burner fuel.
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I would certainly agree that centrifuging WVO through a pressure driven device would not be a good idea. With bio I'm not so sure.
I have recieved the new pump and set it up yesterday. I'm pleased to say it easily pressures up to 100psi+ and still with about 2 litres /min going through the by-pass.
When switched off the fuge now takes 70 seconds to come to a standstill. The glycerine left in the bowl is left as a liquid and not a paste, so not as easy to quantify the result.
Because of this, as the fuge is running down I lift it onto a small container so no contaminated bio runs into the tank.
I've just been calculating the specs again re soap and free glycerine, 66 and 200ppm. On the face of it these seem reasonable amounts, but together they equate to 61mls of glycerol left in a 200 litre batch which seems a massive amount.
The next time I centrifuge a settled batch I will do soap tests before and after to try and calculate the amount of glycerine left in the batch.
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I centrifuged the last batch after washing and drying and sure enough there was a very small amount of glycerol left in the bowl. Strangely enough it is quite liquid whereas on the last smaller fuge it had to be wiped off the bowl.
This being the case, I am aware that as the fuge decelerates some glycerol could run down and weep through the exit (jet) holes. (now it is up to pressure of 100psi it takes about 75 seconds to stop) so I am ready with a small tub and as the fuge runs out of liquid and starts to wind down I lift the fuge onto the tub. I let it drain then wash all the parts down into the tub with a wash bottle containing bio.
My intention was to let the contents settle, pour off the excess bio then transfer the last @ 50 mls into a separating funnel and measure the glycerol. I duly did this and kept checking the tube for the dropped glycerol but there was none there. Then I noticed a small pool on the bench and the bottom tap had been leaking, damn.
I will repeat on the next batch and hopefully quantify exactly how much glycerol the fuge has caught.
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Dave, whether or not you are looking to purchase a centrifuge from them their site is very informative and may help diagnose some of your problems and assist with setup:
https://www.oilybits.com/downloads/OILYBITS_CENTRIFUGAL_FILTRATION_HELP_SHEET.pdf
https://www.oilybits.com/downloads/OILYBITS_OB_SERIES_CENTRIFUGE_SERVICE_INSTRUCTIONS.pdf
I've actually been in talks with them this week with the intention of purchasing an OB-050 wall mountable kit.
It's great to see all your investigative work into perfecting each and every batch of Bio that you produce.
I will be posting another sample to you tomorrow for testing. ;)
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careful, the wall mount ones make a hell of a noise - the vibration from them resonates through the wall
(or it did in the one I saw/heard anyway)
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I'm sure you are correct knightly, the resonance created by my fuge can be ear shattering, If it's in that mood I put a couple of silicone pads between the mounting plate and the base. The buzz at 100psi can be too much.
I will expect your sample Bio Boy.
Since switching over to the big fuge I have realised that what I thought was slight glycerol contamination in the small fuge was probably corrosion out of the bowl, sorry if i confused anyone.
I cleaned out the bowl a couple of days ago after centrifuging about 760 litres of finished bio. It was totally clean, absolutely nothing in it. It seems as if aggressive water washing creates a product that is virtually contaminate free.
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careful, the wall mount ones make a hell of a noise - the vibration from them resonates through the wall
(or it did in the one I saw/heard anyway)
And even noisier if you mount it on a drum, the only way I got one quiet enough to use was to suspend mine with bungie band from a roof joist in me shed.
That is the sole reason for making a bowl fuge.
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I'm going to fix it to he wall with rubber dampers.....
http://www.ebay.co.uk/itm/LAND-ROVER-DEFENDER-90-110-130-AIR-FILTER-MOUNTING-RUBBER-COTTON-REEL-ERR2337-/131613309740?hash=item1ea4c3bb2c:g:WGMAAOSwxCxT42~d
It's going to be placed inside my garage and when in operation I don't necessarily need to be in there. On the odd occasion I need to be I'm sure some ear muffs could be on hand to help me overcome any excessive noise.
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you'll be ok if the garage is detached... not much good if it's on the side of your house :-o
don't want to slag them all off.... but the one I saw made the garage walls hum from the outside... no biggie because it was detached but a bit of a pain if it's on the side of your house :-o
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It's a good job it's a detached garage then. ;D
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I did get a lot of information from the oilybits site when I was setting the thing up. What I would say Bio-Boy is that unless you intend to go the bubble/settle route (which in the long term is what I am looking at) then from what I have found centrifuging well washed and dried bio seems to be a bit of a waste of time. Nothing gets left in the fuge because there in nothing in the bio to get left in the fuge.
A 200 litre batch takes about 20mins to go through, so the buzzing doesn't last for long.
Be careful with your pump selection, most do not give the output that they say. If you use a 50 size it will be the same as mine(I think these things are mostly manufactured by the same people) and to get the thing spinning at 8000rpm+ to do the job with bio you will need to create 100psi in the hydraulic line feeding the fuge.
The oilybits site recommends the puisi viscomat 200/2 pump and from experience this will not supply enough pressure to do the job (even though its' spec suggests it will) So i ended up using the 230/3 and even then it only has a little to spare when running at 100psi. You can really hear the gears churning hard as the by-pass is wound in to get it up to 100psi.
Just to clarify some of my earlier posts. I reported that after fuging my bio with the old smaller oc20 dieselcraft fuge that I found a small amount of brown/black residue in the bowl (which I did) however the anodising on the bowl has started to deteriorate and i think what i was looking as was tiny pieces rust that I had wiped off. Sorry if I confused anyone.
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Dave, the OB-050 wall mountable kit is supplied with the 230/3 pump.
I appreciate that there may not be much to be gained from a fuge in terms of glycerol/soap following the production of good quality water washed bio but I'm chasing the best fuel I can possibly make. I filter to 5 microns and a fuge is capable of sub 1 micron without the expense of replacement filters. The benefit being that should there be any residual glycerol/soap it will reduce these slightly too which is an added bonus.
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Dave at what temps are you centrifuging your bio?
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I do it at ambient. As it is much thinner than WVO there is no need to use heat. The centrifuge does however heat it up a few degrees. Pleased your pump will be the right one.