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Author: Subject: Birkeland-Eyde reactor for making nitric acid.
International Hazard

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[*] posted on 20-11-2014 at 21:28

Thanks for the pointers. I'm trying water-cooled copper capillary tubing right now, to see how that holds up. After all, that's how it worked in industry. The electrodes are holding up somewhat, but there are a few things that I need to adjust in the arc. I'm not spreading the arc far enough yet, and the current is being concentrated too much in certain areas of the electrodes. Aside from that, the water is keeping them cool. I'm using a DI water supply right now, with no recirculation (just runs down the sink). Water runs through the positive electrode, and exits through rubber tubing to the negative electrode. The water is not even warm as it exits.

As I ponder my previous post, I realized that I completely missed something obvious. In the original Birkeland-Eyde reactor design, the supply voltage was 5000VAC, at something like 40A. This is, of course, for a full sized reactor. The current limiting was provided by inductive ballast.

This inductive ballast causes the arc voltage to swing not only below, but above the supply voltage. Think of the arc as if it were a MOSFET in a flyback converter. When the FET is on (low arc voltage), the inductor charges up. When the FET turns off (arc blown out to the edge of the reactor), the inductor dumps its energy through the load resistance. If the load resistance is very high, then the voltage across the FET (arc voltage) can rise to very high levels, at least until the FET avalanches (arc voltage in this case may rise to 10's of thousand of volts). This is a weak analogy, and what is happening in the arc is more complicated than this, but it's the general idea.

Up until now I have been using a 150VDC supply that is current limited to 3A, and with 30 ohms of ballast resistance. Since there is a large output capacitor on the power supply, the voltage does not rise fast enough when the supply goes into current limit. Using the ballast resistor gives a much more stable arc for this reason. Arc spreading is accomplished with an electromagnet that is driven from 10-60Hz AC. The electromagnet core is ground to a point, like in the original reactors. Since I am using a ballast resistor, not an inductor, the arc voltage can never rise above 150V. Resistors don't store energy like inductors do.

The next order of business is to calculate what kind of ballast inductor that I need. It will be determined by load current, electromagnet frequency, and efficiency, among other things. Hopefully my 1cm diameter arc will spread to a 10cm arc with this modification.

Once I get certain issues ironed out, I'll probably start posting pictures.
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[*] posted on 27-12-2015 at 18:46

Will it work?

the titanium dioxide on carbon will take the hydrogen from the water ?

and the flyback can be placed in the magnetron ?

I saw that the magnetron has an input of 4000 volts, the flyback has in its output 30 000 volts, as there is no coil or electronic part within the magnetron believe he can mutiplicar this value?

please help me

g4719.png - 393kB
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[*] posted on 19-1-2016 at 07:05

I'm going to attempt to make nitric acid in a few months with a zvs driven flyback transformer.
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[*] posted on 2-2-2016 at 20:12

Made it. Two minutes will let it redden litmus paper.

[Edited on 3-2-2016 by Hawkguy]

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[*] posted on 2-2-2016 at 21:15

Woot Hawkguy! That is some accomplishment!
Well done.

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[*] posted on 8-8-2017 at 10:49
articles on dielectric barrier discharge

Hi I've found two neat articles that may be of interest to those designing plasma generators for both nitric acid and sulfuric acid. The articles focus on dielectric barrier discharge plasmas as they are supposedly more efficient and less hot than open-arc typical Birkeland-Eyde reactors.

edit: and the arc being less hot allows more generation of NOx without it dissociating and being destroyed from excessive heat.

Attachment: experimental.pdf (1.1MB)
This file has been downloaded 310 times

Attachment: SO2 removal from air with dielectric barrier discharges.pdf (1MB)
This file has been downloaded 213 times

[Edited on 8-8-2017 by physics inclination]
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thumbup.gif posted on 8-8-2017 at 13:03

Quote: Originally posted by axehandle  

"Besides, human lungs can take a lot more than one would think"

axehandle you are without doubt a fucking idiot.

Can you spell "humor" and "irony"?


Its very easy to get blase about NO2. Familiarity breeds complacency, particually when you havnt read the safety data.

You can breathe in NO2 and feel as if youve got away with it, normal, undamaged. Then 8 hours later, up to a day or two, you can drop dead of pulmonary edema. At lesser doses NO2 does largely unnoticed but long term damage to the rather fragile lung tissue. This is not simply caused by the acid NO2 forms as it dissolves with water, its a very reactive free radical - also why its paramagnetic and dark brown.

Well, I've read up on it now, after a very nice person warned me without calling me "a fucking idiot". Apparently it is much more dangerous than I previously thought. I know that now. I'm not senile yet.

You might want to save on you "fucking idiot"s's. People tend to stop reading what you write after you start the childish name-calling.



The thing about people that taste chemicals or test for high voltages with their fingers or hang around neer lit fuses, when everything goes fine people say 'hes, crazy' 'he must be insane' and then grin, and when things go wrong they say 'Oh shit, that was unlucky' or 'he shouldnt have done that' when what they really mean in both cases is 'what a fucking idiot'.

I don't test for high voltages with my fingers, nor do I use fuses at all. I always (fior my rocket engine tests) use electrical ignition with a very long cable hooked up to an apparatus with TWO safety switches.

Nor will I ever "taste test" nitric acid again. Have you heard about learning from one's mistakes?


While in the long run it makes no difference if you kill yourself or when, there will be a lot of other people reading this thread that will assume you know what you are talking about. If you adopt a lax attitude to NO2, they will assume this is acceptable. It isnt.

It's not my responsibility what other people think. And my "lax" attitude is part of my humor, which you obviously don't get. You must be a very boring person, OR there's something wrong with my humor.



Aparently high school physics is letting you down. An arc is a low conductivity path through the air, its low conductivity becuase its hot and (partially) ionised which the current maintains. Hot air rises becuase its less dense than the surrounding air and when it rises it pulls the arc with it since this is the path of least resistance. The arc is rising with the air, not through it. Trimming the ladder until the arc does not break solves a lot of problems, and combined with a static vertical magnetic field should increase yeild substantially (particually concentration in air making it easier to produce better nitric).

That's why the air is pumped in TANGENTIALLY, so that the arc will contact more (turbulent) air than if it where intruduced AXIALLY (w.r.t. the ladder).

I have already discarded, dumped, ditched a static arc, since it would require electrode cooling.


"I AM going to "recycle" some of the NO2 by feedback. "
No, dont do this, it would be bad.

Air passing into the arc comes out with a concentration of nitrogen oxides that does not depend on the amount going in. Its wasted NO2. Aditionally people seem to get better results if the air going into the arc chamber is dry.

Fine. Won't do it then. No problem. Actually, one less problem.


You might want to take heed from the death of a NST in jacobs ladder config particually.
"The company manufacturing this particular NST gave me their word that it would work in a jocob's ladder config."

Read the thread on roguesci. While it will certainly work, how long it will live is more the question. I came to the conclusion that the constant sparking might well be generating fast voltage spikes (eg from inductive kick) that degraded the insulation over time. Its also possible it simply overheated from the neer short current.

Time will tell.


"I'm not intending to make explosives. I'm very afraid of explosives. I AM, however, very interested in rocket fuels."

There is not so much of a difference. What fuel/oxidiser are you planning to make with the nitric acid?

There is a very large difference. Rocket fuels deflagrate, explosives detonate. I was planning on trying out NC to start with.


For the record, I do not have a 'problem' with your project. I hope it succeeds. You are quite entitled to tread your own path, make your own mistakes and we will learn from it either way. I will try to help, you can listen to my suggestions or not, if something is covered well elsewhere I do reserve the right to simply point you to it rather than type it all in myself. If you state as facts things I know to be wrong I do reserve the right to correct them and last but by no means least, if you tell people things are safe when they arnt, if you tell people something is doing less damage to them than they think - when you havnt read the information and very particually when it relates to NO2 - then I do reserve the right to call you a fucking idiot.

Everyone states as fact things that are wrong. It's the listeners responsibility to determine the truth of the statements. I could state that it's safe to jump out a window --- that does not make my fault if someone tries it.

And if you care to point out exactly <i>where</i> I've stated that NO2 is absolutely harmless, I'll accept the ad hominem title "fucking idiot". Mostly because sometimes I'm an idiot, everyone are, but also because I have a girlfriend, which means I'm occasionally fucking.

Does you hardware not support the concept of irony? And why are you so fond of the expression "fucking idiot"? Is there something Mr. Freud would find interesting here?

[Edited on 2004-2-24 by axehandle]

[Edited on 2004-2-24 by axehandle]

[Edited on 2004-2-24 by axehandle]

It's posts like this ^^^^ that really make a 'like' or 'rep' button a necessary addition to the forum soft ware in my most humble of opinion..

I don't want to waste bandwidth (and thus the site owners money)

So rather than quote a whole post.. Just to say I strongly agree with the posters opinion/sentiments..

A simple thumps up could suffice...

A constructive critism is all. Hope it doesn't over step the mark with me being new n all..


E2a I'm sorry but the quote in my box and the one appearing here are different?

If a mod can help? Or just delete? Many thanx.

[Edited on 8-8-2017 by UkAmateur]
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[*] posted on 8-8-2017 at 22:10

NO2 is a toxic gas. However, it is less toxic than chlorine or ozone, which are frequently recommended on this forum. According to this paper:

The odor threshold for NO2 is 0.12 ppm, and the PEL is 5 ppm with an IDLH of 20 ppm. Obviously you don't want to be pushing up against the IDLH and you need to use a respirator but it's not exactly nickel carbonyl, and the smell is an available warning that something is wrong. NO2 is infamous because it's easy to produce it inadvertently from common materials or when trying to do anything with nitric acid (particularly dissolving precious metals).
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