Graham's diagram looks like a classic lamellar separator but with only 2 plates. One could get the same potential gradient with multiple interleaved plates with smaller spacing and less voltage AND less vertical distance for precipitating heavy phase to settle before escaping downwards in the boundary layer.
Get rid of water and magnesol without glowing coronas or safety doubts! If only the sugar catalyst had worked ..**!!/?

quote:

Originally posted by GrahamLaming:
Hi Ant,

I'm not so sure you'd need such a high voltage and such wide spacing.

I've noticed an interesting effect, since using phenolphthalein to make the water and wet soaps more visible, and that is that there is a lot of movement in the liquid, a flow of materials, while the field is applied. I need a magnifying glass to see it clearly.

I can see liquid which was not in the field being sufficiently stirred up by the motion to be brought into the field. It seems to clear the whole lot up OK, if taking a little longer.

so do you think it would be possible to drop something in through the small round hatch on the top of an ibc without having to cut the top off or circulate through a seperate unit?

If you did circulate surely the ideal is to precipitate into some seperate space not back into your main tank?

The goal is seperation after all.

Hi Ant

What have you got in your IBC?

If WVO, I think you'll need heat to reduce viscosity, so the water can freely drop, and I'd think you will need to pass the WVO thru close-spaced plates for effective water separation.

This I've found to be the trickiest separation so far (WVO/water). Too cold and nothing happens.

I do get separation at 50C plus but very little below that, with my part-hydrogenated oil.

I chose 1 re-circulating tank because it is the simplest scheme, then drain off the unwanted product. Separate tanks imposes other challenges of separating the two products effectively.

I've found the blobs of glycerol / water, which this method creates, can be large, so your electrode spacing mustn't be too small or the conductive liquid will short out the plates and you get an oscillating effect - separates, doesn't separate, separates, doesen't separate etc... Vertically long plates make the shorting period last longer. point sources seem to work pretty well.

Fantastic work guys....

I came across something the other day and I wonder if anyone has tried it. Here is a "highlight" from a US Department of Energy report in 1998 about hard water scale. They talk about using magnetic fields to influence the minerals to precipitate out of solution.

"When hard water is heated the mineral ions within the water become agitated and collide causing the minerals to precipitate out of solution. The resulting precipitate is adherent and attaches itself to heat exchange surfaces forming scale. Water moving through a strong magnetic field causes much the same reaction between the positive and negative ions. However, the difference is that the magnetic influence occurs in a cooler environment away from any heat exchange surface. The resulting precipitate is non adherent and will not stick to plumbing surfaces" Link

Would an electro-magnet produce similar results as the electrolysis???

Just a thought, I really don't know much about this and rely on the "one's who know" work to make my BD!

WVO and water isn't what is on my mind, although a great thing in itself if it can produce bone dry oil without vacuum or superheating.

I was thinking partly of glycerol from bio but mostly of KOH soaps from bio.

As you may be aware I have long been against the use of water for washing bio. It's just not green enough for my liking as well as being a right faff about. Wasting a lot of processed drinking quality water on bio is just wrong to me.

So demethalating and settling seems a better option. But fast settling would be awesome.

Not that a humble researcher like myself lays claim to owning IBCs full of bio...

But they are ubiquitous, cheap and a good size.

Hi Ant,

Let's hear it for no water- it is so much better - the contrast is dramatic and I'd be sorely dismayed to have to process and wash bio with water again.

For glycerol removal, the electrostatic system is awesomely fast, and I now use no water in my process, thanks to it.

I should be pleased to bring a few samples up to Newark on the 18th, plus high volatege generator, to demo the effect to anyone interested.

Can demo glycerol separation in 10 seconds, water from bio in 10 seconds, soap from de-meth'd bio in 1 minute, water from WVO ... maybe ... still tinkering with that.

Just need to find a spare 13A socket up there.

I'm up in Birmingham most of this week doing an exhibition, so can't take this experiment much further for a few days.

Cheers for now.

A magneto with a built-in distributor(AKA Wico old tractor mag) would work great. Old engine magnetos could be set up with as many anodes as spark plug holes in the distributor and the barrel as a ground. These additional anodes would provide multi-level fields for complete spearation of the entire BD column. They run 10,000 to about 35000 volts, with very little current - The definition of perfect.

Possible Negatives:
Voltage too high maybe???
Nearly as expensive as insulation testers for a good used one that still throws a spark.
Maybe not enough current?
Bit of a pain to rig up

Here is the ebay item number for a single cylinder magneto: 230032255933

Disclaimer: Know what you are doing before attempting this!

NCDiesel

I have an old Ford Model T coil...the buzzer-type coil that generated a continuous spark for the distributor? Does anyone know if this is pulsed DC or is it AC?

It's been awhile since I used it for practical jokes...

Model-T spark coil "boxes" are AC. Most magnetos are DC. Note about magneto output - if their high tension path to ground is open (very high resistance), they'll find an internal path to ground, usually by arcing across the (expensive) coil inside the housing, causing damage. Better to short them. It'd work for a while though.

You know Johno I can't help thinking that between what Graham has here and your amazingly simple continous processor, with the twin pumps and three static mixers, we have the makings of a complete continous system that is within the grasp of most hobbyists. Mayby using mobious's vertical babbington for heat. I would like a build it yourself guide to your processor if you could point me to it somewhere off this thread... Particularly the static mixers themselves as they seem to be a critical part to it all working. You have shown that continous processing can be made to work without all the theoretical complexity people like colin s proposed before vanishing when it got close to having to put up or shut up. You and Graham are both true pioneers of practical progress here in the bio community (you too Maria and the rest of you). I'm proud of you all and you make me look good just because I keep up with what is going on.

Thanks for the kind words, even at the risk of diverting this thread from the topic. Double-pumper pictures and description are here (eternal thanks to Graydon). If you're mechanically inclined, there should be enough to go on there. Otherwise drop me a line.
Cheers,
JohnO

Whoo Hooo dirt cheap static mixers!!! They not melt in bio then??

I have industrial death machine for insects.
4.5kv 9ma. Any good for a big tank you think? says DANGER big and good. Seems like it could be human death machine also.

does a big tank take more current or just more voltage? would three to six inches be max electrode spacing current limiting also needed?

Also have 9kva 15ma neon transformer dug out from loft.

Hi Ant,

Both sound useful, but with more than enough available current to be lethal. Do be careful!

If you are not experienced in dealing safely with such high voltages, with such high available current, I would recommend you do not use these or similar devices.

If you are experienced and understand the hazards and necessary precautions, here are a few reminders.

Make sure there's no way you can touch the transformer or its output terminals when power is applied.

Also, you should add a resistor string to each output terminal to limit the max. current to a safer level.

For each kV, or 1000 Volts, use 1 Megohms of resistance on EACH terminal, made up from 10 x 100 kilohm 0.6 Watt metal film or carbon resistors in series.



Using a large number of lower value resistors is essential, to distribute the voltage stress and power dissipation across each.

So, for your 4.5kV supply you'll need 2 strings of 45 resistors each, and for your 9kV supply you'll need 2 strings of 90 resistors each.

Do NOT use fewer resistors.

Wire resistors end to end. Slide the string of resistors into some thin, clear pvc tube.

Slide that thin pvc tube into a larger pvc tube. to improve insulation.

The whole assembly should be mounted into a sturdy, well-earthed metal enclosure.

Keep all dry and ensure no possibility of hand contact inside the enclosure.

You could control/reduce the output voltage if you use a variable transformer (variac) to feed the primary.

I would strongly recommend you have a loud buzzer or other warning device which activates whenever you have power connected to your transformer, so you cannot 'forget' that it is switched on.

If you are not experienced in dealing safely with such high voltages, with such high available current, I would recommend you do not use these or similar devices.

Hope that helps.

This message has been edited. Last edited by: GrahamLaming,

It helps a lot Graham as do the links you provided early on and I have just got round to reading into the early hours of the morning.

Marx generators, lightning on a stick with no diodes required whoo very carefull hoo.

Reading around the web on the topic suggests solid carbon resistors are more durable than metal film in high voltatage situations. You do get actual high voltage resistors on ebay sometimes. I assume you could use fewer then?

In any case thanks for the advice. I will be sure to use an earthed case, warning buzzer etc and it is helpfull to know exactly how to limit the current. I do have and will use a variac as well.

I assume it would hold true for any voltage and I could get me a 50kv flyback transformer and limit the output from that in the same way? Probably want to use remote control to switch that on and off though lol. Dont worry I may laugh and joke but I do take the dangers seriously.

Wouldn't my outputs be AC in both cases of the transformers I have though? whilst a flyback would give DC? So need some high voltage rectifiers to give me DC from what I have?

what if I buy a 6Kv 3W DC-DC converter? thats 0.5mA if I have my decimal point right? Would that be safe to use as is or need the same resistor string?

Would it be up to the job in a larger electrode situation?

quote:

Using a large number of lower value resistors is essential, to distribute the voltage stress and power dissipation across each.

Graham, I don't completely agree with your first statement. Voltage stress yes, power dissipation no. What this is really buying you is a 'bend not break' philosophy - i.e. if one or two resistors short out, then you still have the redundancy of more.

What I would do instead, is have a couple of higher ohmage resistors that are rated for a good amount more than the current that will be potentially going through them. Maybe three 330K, 1 watt resistors for each terminal. It buys you the redundancy that you want and it simplifies construction. In fact, I'd probably be a little more liberal and limit current to 10mA vs. 1mA. If you touch it, you'll get a good shock, but, it's still "very safe" insofar as standards go - i.e. its well below typical "let go" amounts. This saves you a little money on the resistors. For each 1kV, I'd go with 2, 50kOhm resistors in series for each terminal. Then I would make a point of installing guarding to limit the possibility of exposure. Remember, this isn't supposed to be touched during operation. Now, if I was in a situation where it was VERY likely that someone(s) might be routinely exposed (stupidity not withstanding - nothing can stop stupidity), I would probably be inclined to limit the current further), but, 10mA that's guarded, in a system that is setup such that someone would actually have to make an effort to get shocked, I think is fine.

quote:

So, for your 4.5kV supply you'll need 2 strings of 45 resistors each, and for your 9kV supply you'll need 2 strings of 90 resistors each.

I don't like that idea because of above, but, there is a very high chance that you are going to have an open circuit that will be difficult to isolate because there are so many connection points.

quote:

Do NOT use fewer resistors.

I agree that you should rely on more than one in series, but, 90 or even 45 is way over kill.

Hi

Check your resistor manufacturer's spec. to see how many volts across the terminals they will tolerate.

A typical (common) 0.6 watt resistor I'd safety rate at 200V, so aim for 1/2 of this.

You'll see then why so many.

Just solder well, and you won't have an open circuit. An open is easy to find - it's where the resistors come apart!

Use many, be safe.

Please correct me if I'm wrong, but this all works because of the magnetic field cause by the current flowing through the liquid...right? If this is correct, why can't we use very strong magnet to create the field. This would be a lot safer and use far less energy. You could design the continuous flow reactor like mentioned earlier using magnet in the "chamber" instead of DC current. If no one has real objections to this, I may find strong magnets and test this out.

Kind Regards,
Martin

http://www.newark.com/NewarkWebCommerce/newark/en_US/en...IIV1?SKU=64K5079&N=0

You can find even carbon resistors that are rated for 1000V. Newark has 'em, I'm sure they are available other places as well.

Madmarvin,

Electromagnetic fields and electrostatic fields are completely different. The high voltage terminal points attract or repel the polar ends of molecules (i.e. soap/water, glycerine) this is what causes the rapid separation.

I don't think an electromagnetic field would have the same effect.

Insofar as power consumption, this method consumes almost zero power. We are talking microamps (if anything) range. It would require FAR more power to produce a large electromagnetic field using electro-magnets.

Best regards,

Wes

Thanks for the clarification. I was thinking of using very strong static neodymium magnets to create the feild, but if the properties are different then they are different. Would have been cool to use static magnets that do not require a power source.