A New Take on HNO3 Prod.

[Meawoppl]

I was thinking about this for some time now, but am not quite sure how feisable it is:

One of the ways to produce NO and thusly strong nitric acid is by spark discharge generating plasma and an elusive bit of 03 and thusly NO. I ran into a website that describes in detail, a way to make a steady plasma arc inside of a microwave oven(http://jlnlabs.online.fr/plasma/gmrtst/), specifically noting on the site "the plasmoid generates ozone (O3) and nitrogen oxydes ( NO and NO2), so you need to do this experiment in an open and well ventiled area."

I have been thinking that this arrangement required far less prep than some sort of television transformer or car winding that I had heard described earlier, and only an old shitty microwave that you dont mind punching a few small holes in and some glass that I think I can get at home depot. Does anyone here think that this arrangement could work?

Secondly, you could use a pump to apply a small forward pressure or ideally build a small stirling engine pump that works to dissipate the heat on the plasma container. That would be way cool, as the process would only have the cost of running the microwave.

Also notably, "the plasmoid is produced in a spherical vessel, it is self-confined ( like a ball lightning ) by spherical pinch effect
and thus the hot plasma is not in contact with the glass vessel" so the glass wont get to hot too quickly and if I understand the physics correctly, the graphite rod is only necessary for starting it, from there, the microwaves can continue to excite the gas.

Do you think this sounds like a reasonable enough experiement to spend $50 at the flea market?

[simply RED]

Even you have NO or NO2 in excess you can not make conc. HNO3 at home.

[Meawoppl]

Another page regarding the same phenemonon:

http://jnaudin.free.fr/html/oa_plsm2.htm

Also the addition some water vapor should make the setup complete.

From my understanding, under plasma conditions, molequels split up and become monoatomic b/c its thermodynamically favorable.
Thusly:
3 O2 + 7 N2 + 5 H2O ---- hv ----> 11 O + 14N + 10H

Other than recombining into their previous compounds, these reactions would take place:

11 O + 11 N ----> 11 NO
3 N + 9H ----> 3 NH3

The NH3 could be condensed out, leaving a higher net oxygen concentration in the system.

Recirculating the gas through chilled water would begin the acid formation process and eventully exhaust the Nitrogen in the system, thusly serving as the oxygen bubbling process.

I doubt that this process is energy efficent if feisable, but if its possible, it could be performed with some simple glassworking, and has a plesent by product of ammonia.
[edited for a typo]

[megalomania]

This sounds like it has some potential, but that is something experimentation will have to bear out.

One problem I foresee is how to use this for production of significant quantities of nitric acid. The best way to do that is with a constant gas flow of air, but if the plasma ball relies on vaporized carbon particles in a confined sphere, any air flow may disrupt plasma formation. In a closed system all you would get is a small quantity of trace NO2 gas and ozone.

Another problem may be too much UV light from the plasma breaking down a significant portion of the NO we do get.

It may be more appropriate to use a catalytic material that lends itself better to NO formation besides carbon. Such a material may need to form an oxide while in the plasma, and the microwave emitter will need to be specially tuned to the materials particular resonance frequency.

[Meawoppl]

I have the spare cash to fund at least some inital inquiry into this project, so I think that I will.

I am going to keep a lookout for acheap ass microwave, and do minor bit of disassembly/violation of the fcc. There is some mention that the actual microwave magnetron is switched on and off 60 times a second to keep it from overheating. I think that I will hardwire it on and add some additional cooling to keep from frying the anode too quickly.
Also I am going to need to find a borosilicate sphere, or blow one from a test tube. If I do one smaller than that huge sphere thing, the heating problem i think will dissapate largely as the V/S.A. ratio gets better. Perhaps a series of small spheres . . . we shall see.

If anyone has any thoughs or experience in this area, please tell me anything you know. There is nothing worse than repeating another persons mistakes and failures.

[simply RED]

If UV does the trick. Use directly UV source (Hg lamp, etc). Find what wavelenght does the trick (UV spectroscopy or by theory) and chose source that emmits mostly there.

Russian scientists experimented with this ("Plasma or UV for HNO3" in 1973 with absolutely no success).
Original article in:
"1975 RADIO (DOSAAF) magazine" forget which month.

[Meawoppl]

There is already plenty of experimental data online about people generationg NO and NO2 via this method. The question is can I somehow form ammonia from those conditions. My suspision is that normally the NO/NO2 pathway is perferred over the NH3 route, as the amount of ozone generated created a very oxidising atmosphere. I bet if the O2 were removed from the vessel, at least some NH3 would come about.

So I am buying a $20 microwave from craigs list, we shall see.

[Alexires]

Meawoppl, I had exactly the same thought last night. If the O2 was burnt out of the air, or somehow removed, then NH3 would probably be produced.

At some point in the following you would need to find a way to input H2. After the bunsen burner stage, maybe have something electrolysing water to form the H2. Not alot of input would be needed, so this is probably better than having a H2 tank.

My idea would be running the air through a dessicator (remove H2O) then burn it using a bunsen burner (the little hole that you open at the bottom). Cool it if necessary, then route it through your microwave gizmo (drill a hole in the door and stand the hell away). Then pass it through a condenser running the dry ice/acetone slurry that is talked about in another thread (http://www.roguesci.org/theforum/water-cooler/5667-dry-ice-acetone-slush.html).

This will hopefully cause some amount of ammonia to be formed, and then liquified through the condenser. Probably most ineconomical, but then the used air could be passed back through the device (this will do away with the dessicator and the oxygen remover).

Leave it going for a while might produce NH3.

[sprocket]

My idea would be running the air through a dessicator (remove H2O) then burn it using a bunsen burner (the little hole that you open at the bottom).If the goal is to produce a dry stream of nitrogen you might want to do it the other way around seeing as the combustion is going to produce a lot of water. Perhaps it would be a good idea to remove the carbon dioxide as well by bubbling it through an alkaline solution, then this needs to be done before the drying as well. The hydrogen inlet needs to be after the combustion step (obviously), but before the drying.

The big problem with removing oxygen through combustion is getting the fuel/air ratio just right.

[Meawoppl]

I have been thinkining for a while now, and I think that this process has become a bit more complicated that originally intentioned. However it could be greatly simplified by splitting the process into three different loops:

Loop 1:
Atmospheric air + O2 --> 03 ---> NO + NO2 ---> Nitric (fuming) + excess NO/NO2 To be recycled through loop
(I know that this loop works)


Loop 2:
Atmospheric Air + H2 --> NH3 + O2 --cooling--> O2 (For the bubbling)
(Looking at some thermodynamic data [and making an estimate of the arc temperature from black body spectra] I think that this could work.)

Is there a way to estimate your K eq from dG (dH and dS data). I seem to recall a link between the two, but I am not sure what to search for.

Loop 3:
Electrolosis of H2O ---> H2 + O2 (For supplying above processeas)
(I KNOW that this works. In fact I have parts for most of the apparatus)

I played with the idea of making loop two utilize some sort of hydrocarbon, but the idea of carbonated nitric acid was enough to turn me off to the process.
Is CO2 a weak base?

Any more thoughts? My first experiment when I pick up the microwave today, will be trying to make some ammonia from water, and air. I will put ingredients in a closed sphere covered with a balloon and then chill the products after some amount of reaction time. Hopefully (if my balloon dosent melt/explode) there will be a bit of dilute NH3.

Any other experiments that you guys would suggest?

[edited for a missing ")"]

[megalomania]

I just love some of the things scientists do in journals. While looking to see if there is any prior published work on microwave production of ammonia I found this…

Microwave irradiation at 4kW for 0.4 sec applied to the heads of mice produced an increase in brain ammonia.

Your mom might not like you sticking firecrackers up a frogs ass, but saying you are testing the effects of application of propellant base to anterior portion of Rana catesbeiana sounds educational.

[Meawoppl]

So what you are saying is that I need a small box full of mice w/ spinal taps? :p

In the relm of meaningful news, someone beat me to the microwave *shakes fist*, but I am sure I will be able to scrounge one up soon.

[Meawoppl]

A large amount of the heating that mircowaves do is due to alignment of dipoles w/ the microwave em feild. I think that this would discourage the formation of NH3 under such circumstances as it is fairly polar. In any case, there is still no progress on the microwave front *shakes fist*. I will keep you all updated.

[nbk2000]

Microwave irradiation at 4kW for 0.4 sec applied to the heads of mice produced an increase in brain ammonia.


Maybe there's more to it than meets the eye.

Perhaps part of larger research on microwave HERF weapons and their use as lethal, or less-lethal, weaponry?

[Meawoppl]

I have read that at Raytheon they are working on something very similar to this, but is is more directed. Some sort of microwave laser.

http://www.defensetech.org/archives/001219.html

[Altroman]

Microwaves are often used to "fix" (i.e. cook) brain tissue in order to preserve the locations of certain neurotransmitters in the cortex. Subsequent sectioning and staining can then reveal these substances. [See: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16176062 Typical RF powers used to cook a rat's brain: 5kW for about 3 seconds - Ouch!

Although far off topic, I mention this because it illustrates how difficult it is to actually use microwaves as a lethal "weapon," since it takes many kW for many seconds to denature just a few cc of gray matter.
Formation of a stable plasma in air with continuous water scrubbing of the exhaust to extract the NO/NO2 gas mixture should far easier to arrange. Either oxide produced in stoichiometrc excess will simply remain undissolved.

[PeterB2]

If you want to make NO2, I read about a way in "The Golden Book of Chemistry Experiments" (page 34 I think). Gently heat a mixture of sodium bisulfate (used in pools) and potassium nitrate together in a test tube in a one to one ratio. If it produces much NO2 at all, the only challenge left is to bubble it through water. I haven't had the weather on my side to be able to try this yet, but if it works well, I'll let you know.

[crazynlazy]

Are you quite sure of that reaction Peter? I had always read that molten sodium bisulfate acts quite similarly to sulfuric acid. Eventually, the sodium bisulfate decomposes yielding sodium sulfate and the hydrogen cation. The hydrogen that is removed from the sodium bisulfate replaces the potassium (and vice versa) in KNO3 thus forming nitric acid. Thus, by mixing potassium nitrate with sodium bisulfate and heating, you get the following reaction:

NaHSO4 + KNO3 --> NaKSO4 + HNO3

Consequently, the nitric acid is obtained, albeit more directly. I am rather sure of this considering I have made hydrochloric acid using sodium chloride and sodium bisulfate. However, I could be wrong.

As for the initial post, this seems like a rather cumbersome way of producing nitric acid. Distillation seems to be a simpler, less toxic form of this synth. But I guess it never hurts to know.

[tmp]

I wouldn't be surprised that NaHSO4 and KNO3 heated in a test tube yields
NO2. The heat in the test tube should decompose the HNO3 that forms.

Decomposition of HNO3 can occur during normal distillation if the temperature
is too high. Oxides of nitrogen from decomposition is what gives the "red"
and "yellow" nitric acids their color. The highly concentrated, "fuming white"
HNO3 is usually distilled under vacuum. The result is a more concentrated
product with little or no decomposition because the vacuum lowers the
boiling point. I said "usually distilled under vacuum", because a method was
devised that could produce white nitric without distillation. Even in that
method temperature determined if the acid came out "red" or "white". At
60C the acid came out "white".

If the bisulphate is all you can get your hands on, go for it ! I was at the
hardware store yesterday. They had plenty of H2SO4 drain cleaner on the
shelf so I'll stick with vacuum distillation for now.

[PeterB2]

Crazynlazy, no, I am not sure about the reaction--I only read it in the book and have never tried it myself but thought it would be worth a shot. After if it is in a published book (albeit, a banned book), then it should be fairly legitimate.

Yes, I have some sulfuric acid drain cleaner as well and would like to try nitric acid sythesis when I get the chance. I thought the whole argument was that NO2 and water would generate a more concentrated and purer product and thus worth some investigation as an expedient means of sythesis.

Having just begun my journey through the fascinating world of chemistry though, I do not have a distillation apparatus (other than the one described at http://www.hometrainingtools.com/misc/CE-DISTIL1.pdf which involves rubber stoppers which would be corroded by nitric acid) or a vacuum pump yet. I'd like to try the method described in the "Nitric acid the easy way" thread. Not terribly effective but easy and cheap.

[simply RED]

"Although far off topic, I mention this because it illustrates how difficult it is to actually use microwaves as a lethal "weapon," since it takes many kW for many seconds to denature just a few cc of gray matter."

This is true if you use microwaves - THz in order to thermally destroy the targeted tissue. This part of the spectra, however also has non-thermal effects especially on the nervous system. One possible way to create non-thermal microwave-THz weapon is to adjust the radiation frequency to a peak in the absorbtion spectra of vital biomolecule in vivo.

[c.Tech]

I would have thought the sodium bisulfate reaction would go more like this.

2NaHSO4 -> Na2SO4 + H2SO4
As it usually does in ethanol and water.

Then the general reaction between a nitrate and sulfuric acid takes place.

[crazynlazy]

IIRC the decomposition reactions for sodium bisulfate is as follows:

At 315 degrees Celsius: 2NaHSO4 --> H2O + Na2S2O7
At 460 degrees Celsius: Na2S2O7 --> SO3 + Na2SO4

So I imagine that all of the water would have boiled off from the preliminary decomposition. And the latter decomposition yielding sulfur trioxide would combine with any water that might be left in the air yielding sulfuric acid. Plus, even if 0 - 460 was achieved quickly, sulfuric acid would protonate the sodium sulfate leaving only sodium bisulfate which would then repeat the reaction until sodium sulfate was the only remaining substance. However I could be wrong about this as well, I am no chemistry expert.

While I realize now that my synth. is incorrect on many levels. I do however still think that the replacement reaction happens. It being the only logical reaction that I can see given the decomposition reactions. I would, although appreciate if anyone could tell me why it wasn't. My basis for information was the reaction I had performed with sodium chloride and sodium bisulfate which would give one reason to believe that the corresponding acid: nitric acid would be created, and proceed to be decomposed as tmp pointed out.

So I'm going to have to scratch what I said earlier about the reaction and agree with PeterB2 and tmp. Thanks for pointing that one out.

As for a contribution to the production of NO2. Use strontium nitrate as opposed to potassium nitrate. It's higher decomposition temp. allows higher quantities to be used with more ease.

Edit: I apologize for any ambiguity, I meant degrees Celsius.

++++++++

You didn't bother to mention whether the degrees were in Celsius or Fahrenheit. In science, the importance of such details is immeasurable.

NBK

[megalomania]

Ahem… back to the original topic: I quite forgot about this thread, so I guess it is serendipity that I checked it today because I found an interesting journal article recently. I am somewhat out of my depth with this one, but I think it has potential to be an interesting experiment.

The article is Microwave Torch as a Plasmachemical Generator of Nitric Oxides from the last issue of Plasma Physics Reports, 2006, Vol. 32, No. 6, pp. 520–524.

Abstract - The possibility of using a microwave coaxial plasmatron (a microwave torch) as an efficient plasmachemical generator of nitric oxides in an air jet has been studied experimentally. A plasmachemical model of the generator is developed. Results of calculations by this model do not contradict experimental results. A conclusion about the mechanisms governing NOx production in a plasma torch is drawn by comparing the experimental and calculated results.

The device seems simple enough to my untrained eye, all that is needed is a coaxial waveguide. Since I have no idea what the hell that is, I looked it up. Fortunately the journal included a reference to an earlier publication that describes exactly how to make one of these coaxial waveguides. Unfortunately I don’t know precisely what they are talking about. I think, only my gleaning, that the waveguide is just some wire. The earlier journal article is not exactly as clear as I would like it to be. Perhaps a more mechanically inclined member can look over the publication.

Here is a clipping of the experimental setup. The deuterium lamp, Spectra 1600, and S2000 parts are only for this experiment’s experimental analysis of gaseous products. These components are NOT needed to make NOx.

http://www.roguesci.org/images/1-20-07_01.jpg

In the picture it appears as if the magnetron directs the microwaves into the waveguide. In the prior article the setup is a bit more detailed. Here is where I am having trouble: The earlier article specifies the magnetron directs the microwaves into a “rectangular resonator.” Maybe I slept through that class in physics, but what exactly is a rectangular resonator? What is it made of? can I make one? Do I even need it to make NOx?

http://www.roguesci.org/images/1-20-07_02.jpg

Lets hear from the learned members of The Forum. Any thoughts on how to build a coaxial waveguide? Is this experimental setup as simple as I think: a consumer grade microwave magnetron direction the microwaves onto a bit of spiky wires with a guide wire around it, and a jet of air blowing in the middle of it. Can it be that simple?

Oh, look! Someone has uploaded all three articles (there is another article that discusses the setup) to rapidshare moments before I posted this. Thanks anonymous uploader, you are both a genius and handsome :)

Microwave Torch as a Plasmachemical Generator of Nitric Oxides. Plasma Physics Reports, 2006, Vol. 32, No. 6, pp. 520–524. (http://rapidshare.com/files/12590908/Microwave_Torch_as_a_Plasmachemical_Generator_of_N itric_Oxides.pdf.html)

A Pulse-Periodic Torch in a Coaxial Waveguide: Formation Dynamics and Spatial Structure. Plasma Physics Reports, Vol. 30, No. 3, 2004, pp. 255–262. Translated from Fizika Plazmy, Vol. 30, No. 3, 2004, pp. 283–291. (http://rapidshare.com/files/12590909/A_Pulse-Periodic_Torch_in_a_Coaxial_Waveguide.pdf.html)

Repetitive Torch in a Coaxial Waveguide: Temperature of the Neutral Component. Plasma Physics Reports, Vol. 30, No. 6, 2004, pp. 531–541. Translated from Fizika Plazmy, Vol. 30, No. 6, 2004, pp. 575–585. (http://rapidshare.com/files/12590910/Repetitive_Torch_in_a_Coaxial_Waveguide.pdf.html)

[sparkchaser]

The rectangular resonator should just be a metal box, or even fine wire mesh that has holes less than one wavelength in diameter. The resonator basically directs the energy into the air tube, and uses the outer tube as a shielding ground. Think coaxial cable, it's the same principle.

[Meawoppl]

A gf and two job changes later I am back on the project, and really want to get this rolling. I hear that making explosives is therapeutic. I AM buying a microwave from Wal-Mart tomorrow, no more of that Craigs's list shit.

[Al Sheik Yerbuti]

It will take more than just slapping together some free-formed (hand-bent) mesh and some improvised pipe: for example, did you notice the temperatures that this toy can reach? Up to 7000K!! That's around 6700 Celsius, or over 12,000 Farenheit!! And you'll be moving 5 to 10 liters/min of air at that temperature. Just for your own personal protection you will need a welding mask, full-faced and I'm guessing at least a #12 shade lens--maybe more. A full suit and gloves.... You know, now that I think about it, I wonder what kind of x-rays may come off of the electrons kicked around at that temperature. Not insurmountable, but you might want to investigate that.

From what else I gleaned from between the lines, the rectangular box is not an ideal design and some waveform analysis should be made not only for the resonator, but for the coax channel afterwards. The trick that they are using is a lot like a pipe on a pipe organ. It needs to set up a resonance along the outer electrode, and then as the waveform reaches an antinode, the inner electrode abruptly stops and releases the air. The microwaves are focused at that point like the sun's rays through a magnifying glass on a poor hapless ant, initiating the plasma pulses (occuring at around 8 microseconds, or around 125,000 times per second IIRC) which, thanks to the heat capacity of the air, quickly averages out to a steady plasma torch....

But back to the issue, the electrodes will need to be tuned to catch an antinode just right, and the two electrodes will need to be not only extremely circular (as in lens quality) but also perfectly concentric for the entire length of the z-travel.

But otherwise it sounds easy enough. :rolleyes: It would make one hell of a plasma cutter for steel or even a high-tech initiator!

Anyway, there are some serious issues but they could either be solved through lots of calculations (enough to give you a headache to rival a nitro-throbber) or some intuitive guesswork and some engineering methods to work around all that mess.

Good luck, I'm dyin' to see how it goes!

[megalomania]

Al Sheik Yerbuti, you seem quite knowledgeable on the this topic. Could you perhaps recommend any engineering books that describe the selection or creation of acceptable resonator chambers or design of microwave equipment? I have a few books underway, but I am not sure what the proper terms are to do an effective search to find good literature.

The suggestion about the x-rays is very intriguing. Talk about unintended consequences.

It is not so difficult to get plasma in a microwave. I have seen video footage of a modified microwave producing flashes of plasma from candle smoke. Achieving a steady flow of plasma for consistent production of nitric oxides is entirely a different matter, and will require much experimentation.

However, if all you have to start with is wire mesh and bent tubes, those are better than a mountain of equations because equations never actually made anything. At least you may find out what does not work and can warn others about your failures so that they do not repeat your earlier fumblings.

[jpsmith123]

Unfortunately I'm not yet in a position to do any meaningful experiments myself, but I have some ideas that might be helpful.

I think there are several ways that microwaves could be used to make NOx; e.g., U.S. Patent #6696662 describes another potentially useful setup that may be easier to rig up.

I have the patent in pdf format, but I'm not sure how to upload it here.

Anyway, the primary usefulness of microwaves seems to be the ability to form a uniform, high temperature plasma in air at *atmospheric pressure*.

Moreover, I've seen several peer reviewed journal papers (mostly in the journal "The Review of Scientific Instruments", I think) where people have constructed various plasma-producing scientific apparatus from commercial microwave ovens.

In any case, as I see it, the technical issues are: 1) to create some ions in the air, thereby creating some conductivity whereby the microwaves can deposit energy in the air; 2) confine the plasma to a defined space, without burning up anything or contaminating the product; 3) present a reasonable load to the magnetron to keep the efficiency reasonable and avoid premature failure of the magnetron; and 4) avoid hurting yourself with stray microwave radiation, high voltage, or product gasses.

It may be possible to use a microwave oven almost "as is"; i.e., with only a few modifications. In accordance with the above, the main issues there would seem to be: getting air in and out, obviously without allowing significant microwave leakage, confining the electric field to a volume smaller than the whole cooking chamber (to get a higher temperature plasma), and getting some ions to start the process.

The below linked page shows plasma generation inside an oven, and thus makes me think the idea is basically feasible.

http://jlnlabs.online.fr/plasma/gmrtst/

[Al Sheik Yerbuti]

As I said, much of the equationeering can be avoided through intuition and some engineering methods. Probably the best workaround that an engineer could do to bypass the math is experimentation and the collection of empirical data. (Before any other engineers get mad at me I better include that to formulate equations which describe and predict the empirical data is good, too).

I will look to see if I can locate any books which will be helpful towards this end. I would not look into engineering books at first for this. Conceptual matters such as this would be found more readily in physics, under electro-optics. Best bet for beginning the quest is any undergraduate level text in general physics, in the optics section, then see where that takes you.

If you happen to be producing arcs of electricity, then depending on the voltages being generated, you are very likely to be producing x-rays and UV. How much I can't predict at this stage, because we have no real working design yet, except what the Russians used in their setup. They included only sufficient information about their design to demonstrate the concept and no more--in other words they have mostly kept it secret what they designed. Depending on the amount of incidental x-rays produced, it could be no more problematic that x-rays from your television or it could be enough to kill you from either killing ribbons of flesh through your body (depending on where, by chance, they become spatially focused) to inducing cancers by the ionizing disruption of your RNA etc.

Arcs of flash electricity in the microwave certainly are easy to produce but causing them to be localized and controlled will be much more of a challenge, yes.

There is a compromise between slapping stuff together and pure equations. One is blind and the other is crippled. You will recall that Marie Curie made great advances for the cause of science, yet paid the price of ignorance with her life. (When I use ignorance and Mme. Curie in the same sentence I mean it with only the greatest respect; it was, however, the frontiers of human ignorance that she was exploring. So no flames, thank you.)

I'll have to do some reading on this subject before being able to offer any more concrete information, but in the meanwhile be aware that whoever assembles a prototype of this nature should take precautions against high-voltage, dangerous currents, UV, x-ray, IR, loose microwaves, high-temperature plasma streams, and of course, NOx and other threats.

I'll try to brush up on some of these topics.

__________________________________________________ ___

EDIT #1

Wow, there you go. JPSmith123 snuck in right as I was posting. So imagine this: get your reactor chamber (the ball glass in JP's link) and devise a method to create a cross-flow of gas (or air) through the vessel. I am envisioning a three-necked reaction vessel, or distillation flask. From there, a couple hoses, drill a few strategic holes in the oven, and the rest should be simple enough!! Good job JP!

__________________________________________________ ___

EDIT #2

I had to try it--I made a circle of cardboard and covered it with aluminum foil. I took a standard pencil and removed the eraser end, and exposed additional lead at the bottom to make contact with the aluminum disk. I inverted a round 500ml flask and sharpened the pencil to a length where it reached just a little into the sphere of the flask. I placed the pencil in the flask and set the flask onto the disk in the microwave. I turned on the power for 15 seconds and noticed nothing. Upon investigation, the pencil was hot. I hypothesized that the wood could be interfering with some effect so I carefully removed all the wood from the lead and had a single length of the pencil lead. I retried the above experiment and noticed a couple small sparks at the graphite-aluminum interface. The aluminum was found to be burned through, preventing further contact. In the trash I was able to locate a lid from a can of orange juice which I cleaned and substituted for the aluminum-covered cardboard. This time, some sparks worked their way up the lead until it reached the tip, whereupon it generated a small ball-like source of bright light! It was steady and blue as one could see from a welder. I shut off the microwave to investigate. Inside, the lead had broken in two. This must have occurred when I turned off the power. Where the lead was touching the flask in the sphere portion, the borosilicate glass had melted and a set of small circular cracks had appeared. The flask was otherwise filled with a thick, white smoke of unknown composition. It smelled waxy and i hypothesize it to be binder from the pencil lead. The OJ lid has carbon deposits on it, signs of heat burnthrough as if it is a coated steel. The lid was cleaned of this and shows minor damage. The lid was also extremely waxy, and I'm wondering if some wax may have remained from the cardboard sides of the OJ can it came from, and escaped my cleaning. The pencil lead (graphite composition) shows definite burnoff at the sharpened tip. There are whitish deposits at the other end where it touched the OJ lid. The shaft of the graphite shows an exudate of a nearly black color, sticky and bubbly. It reminds me of burned sugar. Where the graphite broke, it shows definite signs of a miniature explosion, and I hypothesize that a small bit of this exudate has vaporized and popped, similar to a popcorn kernel.

Improvements: 1. Use pure graphite. 2. Do not allow graphite to contact glassware. 3. Be certain that all components are very clean.

Further results when available


__________________________________________________ ___

EDIT #3

I've varied some parameters with little success. I've tried steel as an electrode (a nail) with little success. It did get hot which makes me think it has too much resistance. Maybe a piece of copper? I tried the nail both sitting loose on the reflector, in which case the nail and the reflector sparked on each other. I tried the nail welded to the reflector, and nothing observable occurred. I made a larger reflector by using an old paint can bottom, can-opened. I did not notice any improvement. I retried my pencil lead, once pinched into a hole on the reflector to hold it upright. There were sparks at the pinch, but no more. I put the lead back in the original way, just sitting on the reflector and leaning on the neck of the flask. This time it worked as originally described, and I have another burn, melt and crack in the flask. I think I'm spinning my wheels until I understand better the information from jdsmith123's link, and now I notice Meawoppl has one, I'll read that also.

[Meawoppl]

I have purchased an expendable microwave, and have begun experimentation.
The best directions I have found to date come from here:
http://jnaudin.free.fr/html/oa_plsm4.htm

Which details the particulars of getting a "stable plasmoid" going. It seems like you need to create a small flame to get things going, and they have good directions for creating something that self ignites.

Really, I am not sure if a stable plasmoid is what we need. True it would provide a large amount volume to absorb microwaves and thusly lots of O3, But it also creates LOTS of localized heat.

I can see a similar "ashtray" sort of solution working, with lots of carbon dust, therefore arcing therefore O3. Or perhaps if the plasmoid were unstable, (popping in and out each couple seconds, heat managment might be easier.

As for x-rays, I am not too concerned. I was under the impression that it was nearly impossible to get significant x-ray emmissions from the lighter elements, as the outer electron shells are too tightly bound to allow the stripping of e-'s necessary. Secondly, the difference in energy levels was low for transitions between levels to be in the energy range of x-rays. I could be wrong, I have only ever had a class on "Experimental Microstructure Analysis" that talked about x-ray production as more of a side note.
Please correct me if I am wrong on the above, I want to make sure I wear my lead foil underwear.

I have a good feeling on how I want to design the chamber. I plan on drawing it all out tomorrow at work to avoid a slew of questions that will arise purely from describing a theoretical complex assembly.

One last thought, if the final HNO3 had a bunch of carbon grit in it, would cause any real problems? I suppose it would be removed by distillation anyway, just thinking.

[Al Sheik Yerbuti]

As for x-rays, I am not too concerned. I was under the impression that it was nearly impossible to get significant x-ray emmissions from the lighter elements, as the outer electron shells are too tightly bound to allow the stripping of e-'s necessary. Secondly, the difference in energy levels was low for transitions between levels to be in the energy range of x-rays.

Certainly in this new setup, with a ball and carbon thing I don't see much x-ray production. It was the other setup with a resonance chamber and concentric electrodes that I was concerned about, epecially if there were no shielding, which might occur by disassembling a microwave and with an open-ended waveguide. It would depend on the arcing and the voltages generated; x-rays are most often produced by the deceleration of electrons impacting metal targets and their production is therfore voltage dependent, not element dependent. For example, an arc welder or a plasma cutter produces copius amounts of UV which is one to two orders of magnitude less energetic than x-rays, but with just a few thousand volts higher potential, you are making x-rays. But still, the more I think about it the less I am worried about x-rays from these devices myself.

Still, I'd make a simple test with your prototype, though: take a disposable camera (or even just a roll of film, not digital) and keep it about the device. make sure no metal is shielding the film, including the camera body, inside, or if you're using film, the film canister. Of course, keep it away from all light. After running the device for some time, take the film in for developing. black pics are negative, grey to white is positive.

[nbk2000]

Go to YouTube and search for grape plasma. A simple grape will form a plasma ball in 10 seconds (sometimes), and there's your starter. :)

[Alexires]

Actually Al Sheik Yerbuti, I'm going to have to refute your claim that x-ray production is voltage dependent.

As I understand it, when you excite an electron out of its ground state, there are a variety of energy levels that it may jump to, depending on what element it is. When the electron "falls" back, it will emit a photon of corrosponding energy equal to the energy absorbed and also, of a wavelength dependant on the "distance" that it has fallen.

Otherwise, photons can be made from "knocking" electrons from the lowest shell (K shell) and then an electron falls from the L shell to take its place.

I know most of that is right, although I'm not sure about the wavelength bit. Not all elements will produce x-rays, and my argument is supported here (http://ie.lbl.gov/xray/mainpage.htm).

From Giancoli's "Physics" (5th Ed.) in Chapter 28, we find that we can predict the wavelength of photons given from a specific energy level drop. The explaination says that the wavelength of an energy level transition is dependant on Z2 (Z=No. of Electrons in an Element)

Example 28-7
Estimate the wavelength for an n=2 to n=1 transition in molybdenum (Z=42). What is the energy of such a photon?

Solution: We use the Bohr formula (Z2) with Z2 replaced by (Z-1)2=(41)2.

Wavelength propotionally = 1/((Z-1)2)

Therefore, Wavelength = (1.22x10-7m)/(41)2=0.073nm.

This is close to the measured value of 0.071nm.

If you didn't understand that, say so and I'll try an explain using Giancoli.

Anyway, it doesn't really matter. That website above says that x-rays aren't produced from elements under Calcium.

[Al Sheik Yerbuti]

Ah, my new good friend Alexires, thank you for bringing this up. It could be clarified further. I believe we are talking about two different issues. Yes I agree with you that elements with large Z^2 values will have characteristic x-ray spectra, most certainly. In our present application we will be dealing most likely with iron and possibly some steel alloys with chromium. Either of these will be able to produce x-rays by the method that you are referring to, and so will other common elements. There will be characteristic frequencies in each element's emission spectra corresponding to the excitation energy of each electron in an element's various orbital locations. Yes, some of these can and do attain energies in the x-ray spectra.

I, however, was referring to the production of x-rays as if in an x-ray tube, possibly produced in the waveform portion of the microwave plasma generator. If voltages were to occur in excess of a few thousand volts it is quite possible. The effect is referred to as bremsstrahlung which is german for "braking radiation". Through this phenomenon, the energy of the photon of an x-ray can be precisely manipulated by the variation of the voltage in the x-ray tube. The electrons on a cathode are accelerated by the voltage difference towards the anode. For the production of x-rays, the anode is angled outward and as the electrons strike and abruptly stop on the anode's surface, x-rays are emitted at around 90 degrees (perpendicular) to the electron's path. As we all know, voltage is a continuum and therefore the x-ray wavelength in this setup is tunable to whatever frequency is desired. It is, therefore, voltage dependent.

In fact, even in the case of an element which has one of its electrons excited out of the ground state, when returning to the ground state, as it emits an x-ray photon, its frequency and its energy is directly related to its voltage drop, and is therefore, voltage dependent.

What you will find is that an element's characteristic spectrum is element dependent.

But more on topic, I am concerned somewhat that this bremsstrahlung effect could occur in any situation where we find ourselves dealing with voltages in the many kV range, which is very possible with this plasma.

Say, I cannot find the tags for superscript, how are you able to format your formulae so nicely, Alexires?

[megalomania]

The tags are sup and sub enclosed in the usual brackets. I need to stick the graphics for those back in the quick editor...

[Meawoppl]

It seems that this thread has evolved into two separate sub threads, one discussing the production of HNO3 in a microwave oven, a second, discussing the use of a largish microwave assembly detailed in some literature earlier. Just wanted to let everyone know.

As setup in the microwave oven, x-rays will not be an issue, this may not be true for the other experimental setup.

[jpsmith123]

Meawoppl, did you check out the patent I mentioned? The inventive apparatus is very simple.

It's a closed rectangular waveguide with holes drilled about 1/4 wavelength from the closed end (so that the plasma occurs where you would have a high electric field), with a quartz tube inserted through the holes through which the gas flows.

The gas is introduced into the tube through a small metal tube which also serves as an ignitor (apparently by way of corona created by field enhancement at the edge of the tube).

My thought was to recreate this setup inside the microwave oven, for safety and ease of construction. IOW, you basically extend the waveguide that feeds the cooking chamber, to a convenient length into the chamber. The two opposing sides of the waveguide extension perpendicular to the quartz tube now confine the electric field (assuming TE10 mode in the guide), thereby concentrating the field.

Of course it's hard to say without trying it, but you may get satisfactory results if you just run a quartz tube through the cooking chamber without trying to concentrate the field. It may help to map the field somehow first to find a good "hotspot"...maybe using an array of marshmellows or something that would give a visual indication of relative power vs. position inside the cooking chamber.

[megalomania]

You know, I remembered yesterday that I once discussed this same topic a few years ago. My thread is "Zapping my way to nitric with a Marx generator" http://roguesci.org/theforum/showthread.php?t=1757

I shall merge these two threads in a few days just to let everyone know where this one will be going. The content is similar enough to warrant their combination.

I was going to suggest you look into using a Marx generator when I remembered talking about this before. Then I found my old thread. The original link that describes how to make a Marx generator no longer has that information, but I found many more websites after a brief Google search.

I wanted to comment that although industry has given up on the idea of the Birkeland-Eyde Reactor, this method of producing nitric acid is far more accommodating to the bench scale lab of the amateur experimenter or hobbiest. Quite frankly getting ammonia and platinum is far more difficult and expensive in the short term than obtaining a HV power source and air.

The ammonia burning process needs far greater precision and optimization to get it to work. The electric arc just works every time. It may not be the most efficient process, or economic process, but it just plain works.

[Al Sheik Yerbuti]

Another thought I had on this was the use of a device that I have which is ready to go, almost as is. It is my plasma cutter. It has a built-in air compressor, and pushes air through the center of the electrode (not sure if its the cathode) and heats up the air into a conductive plasma. The current then passes into the metal, melting it, thus allowing the plasmified air to burn through the metal. I would have to do minor fabrications to channel the air into the post-plasma stage.

866 (plasma in photo around 2 cm long)

Which brings up another topic, what EXACTLY do we do with this enriched air? I'm thinking that the simplest option would be to bubble it into a tall PVC pipe (to increase absorption) filled with a concentrated brine of KCl. Refinement of the brine after a certain reaction time might yield what--KNO2, KNO3, and release Cl2? Someone should verify this, I am not a chemist. (I'm mechanical FYI). Any thoughts?

[Alexires]

I wrote this last night, but as the forum went down JUST as I tried to post it, I'll post it now.

Al Sheik Yerbuti - Ahhh, ofcourse. Forgot about that one, it has been 2 years since I did physics. E=hf, where E is energy, h is planks constant (about 6.63x10-34) and f is frequency.

Sorry all, looks like an electron with changing velocity will throw off energy of frequency E/h.

Then question now becomes, do the electrons that are ionized inside a microwave oven have the energy to give off x-rays?

Forgive me if I am incorrect, but 1 microwave photon (of 2.45x109Hz) has about 1.62x10-24J of energy (using E=hf), which means the MAXIMUM amount of energy (Ek) that an electron could have is the same.

The minimum energy for x-rays are several orders of magnitude above this energy (x-rays have energys from 1.98x10-17 upwards). So, unless my maths suck ass (which it does, but still), that means that one electron would need to be hit with 1.2247537x106 microwaves before it has the energy to give off 1 x-ray (and come to a complete stop).

What are the chances of that happening?

Al Sheik Yerbuti - Are you sure about how the plasma cutter works?

Have a look here (http://science.howstuffworks.com/plasma-cutter4.htm).

I think you may be fantasizing a little by using a plasma cutter. A mig welder might be adapted to create your plasma easily, but I'm not too sure about the plasma cutter. Then again, I have no practical knowledge of how either work, just what I have gleaned off the internet, so feel free to argue.

Actually, a mig would work, if you could work out how to replace the feed wire with something that won't melt and the inert gas with atmospheric air. Buy a cheap mig and pull it apart...

[Al Sheik Yerbuti]

Hi Alexires. Interesting calculations. Try it this way: Large numbers of microwave photons attack the surface of the electrode/waveguide. Many electrons are stripped away and removed in an ionized stream, leaving behind an increasing voltage potential. It only would take a couple thousand volts for theoretical UV production, and as a ballpark number, ten thousand volts to have the velocity for x-ray production. In that case, energy is proportional to the square of the velocity BTW.

Your number of 1.2x106 is an impressive size, but remember that one Coulomb contains the charge of 6.2x1018 electrons (or protons, for that matter) and your number is a mere 1.9x10-13 the size, or about two - ten-billionth of a coulomb. How does that relate to our understanding? One Ampere passes one Coulomb of charge every second. As an example, a microwave of 800 Watts (by American voltage of 120V) will pass around 7 Amps per second, which is 35 billion times 1.2x106. Every second.

Frankly, I don't see this as being fruitful. I can go from direct experience, that my welder (which happens to be a small MIG welder) will quickly burn my skin from its UV emissions, as my arms will attest. It is supplied by a household current of 120V, 20A. It's output is 90A, which gives a maximum theoretical output voltage of 27 Volts. This 27 volts is sufficient to produce all the UV needed to blister my skin in just a few minutes of welding. I have a very small homeowner-sized unit. Imagine what an industrial unit can produce.

As far as using the MIG for this job, it is completely unfeasible. As stated earlier, it only produces around 27V and requires a current sink (the workpiece) to maintain the spark. As a matter of fact, the wire is repeatedly submerged into the weld puddle, hunderds of times a second, and the resistance of the heated wire at the puddle focuses the power at that point, causing the wire to explode (vaporize) and to break the circuit. The wire is advanced, resubmerged in the puddle, and the process repeated.

One may hook up a range of shield gasses, I prefer C-25 for general use, which is 75% CO2 and 25% Argon. One could use no gas at all, using a special wire with a flux core, in which case the MIG welder is now properly called a FCAW welder. My cheapie home unit can do both, but the FCAW method, while slightly more portable, stinks and splatters and IMHO, produces a vastly inferior weld.

Now on to the plasma cutter: I can promise you I know more about its operation than a tiny article in "HowStuffWorks" could convey. That borders on insulting, Alexires. (But you're still my buddy) I am assuming that everyone is able to see the photo that I posted in post #40? The image shows the hot gasses being ejected into the atmosphere, quite clearly in a plasma state. The particular unit that I own has, as I said, an internal air pump and shoots this stream of air up the hose, and through the electrode where it is heated and charged and ejected in a plasma stream. This is in fact the device most likely to produce results for us. I believe this device WILL work. The welders are too low of voltage and infeasible to modify to our end. IOW they will NOT work.

If you are curious, my welder is a Lincoln Electric SP125 Plus and my plasma cutter is a Hypertherm PowerMax 190C. Readily viewable on the WWW.

I seriously advise against pulling apart a welder and screwing around with that, unless you are a very experienced electrician! It is deadly inside. Although I agree that any hands-on types like us should have welders.... So get one, use it, but don't ruin it!

[jpsmith123]

U.S. patent #5692495 (assignee: BOC Group) claims that passing "air, oxygen-enriched air, or air containing a small amount of ammonia over a noble metal catalyst at an elevated temperature (500 to 1200 degrees C)" will make NOx.

I was aware of the use of platinum to make NOx from ammonia, but I'd never heard of it used just with air.

Also, I have a paper describing a classroom demonstration of "acid rain", wherein NOx is made from an oxyhydrogen flame.

I have both the patent and the paper in pdf format. Is there any way to upload them here?

++++++++++

No need. Anyone here for some time knows how to find patents. NBK

[Meawoppl]

I started playing around with my microwave today some small results:

I setup two pieces of graphite mechanical pencil lead in a cork separated by a small amount and got some pretty impressive arcs/plasma going.

Curiously, when covered with a glass mug it no longer sparks. I think that the glass is soaking up too much energy (it get rather warm), so I am going to seek out a thinner vessel tomorrow.

Ideally, I would want to do it all in a modified test tube with light negative pressure pulling through a condenser with some steam. That sounds like it could work well.

I will update again tomorrow.

[Alexires]

Al Sheik Yerbuti - I'm sorry if I offended you. I was simply asking if you knew about plasma cutters and mig welding. I know barely anything about either of them, so anyone would be better qualified than I in regards to them.

As much as I have enjoyed talking with you about this, we haven't really resolved anything. Personally, I doubt that you will be in danger of x-rays when trying to produce NOx in a microwave, but, if Al Sheik or any other forum members think that there is a danger, I would recommend lead sheilding around the microwave. At least a few mm thick. Think about it. Personally, I'd rather die from some SHERPA (thanks NBK) than from cancer.

If there is the case of dislodging electrons, we might think about using that to our advantage. Electromagnets aren't hard to make, and something that acts like a SEM (Scanning Electron Microscope), just without the viewer might be useful in generating high temperatures. Ofcourse, this idea isn't overly feasable, and I would try the microwave idea before trying to concentrate a beam of e-.

Also, in response to Meawoppl's latest post in this thread, why do we need to have a glass bulb around the plasma? If we could focus the microwaves in some way, or create a stable(ish) plasma, why bother with the glass. It simply causes problems (cooling, air supply, etc.). Then again, from what I have read, it is necessary, but why, I am not sure.

Still, I think the other thread regarding passing air through a jacobs ladder, or arc of some kind is alot more feasable than making a NOx producer from an old microwave.

RTPB principal, KISS. Lets go back to the basics. We are looking at a different approach than the arc way of making NOx (although making an arc in a microwave certainly would be useful, but probably in the other thread).


I think I have an old microwave at home. I'll have a little look over the weekend, see if I can find it and turn it into an experimental apparatus.

[Al Sheik Yerbuti]

No offense taken my good friend Alexires! I've been on forums before, it's a form of communication rife with misinterpretation. I am proud of your commitment to factuality. I am also happy to be investigating this topic with you. Keep us on our toes!

I agree we could spend more time now in constructing functional models and less in academic masturbation. As a practical solution to the fear of x-ray, a roll of film may work well as a detector. Also, I saw recently that there were inexpensive x-ray detector tags at http://www.sciplus.com/ , get them while they're hot! For UV fears, a bit of SPF works wonders.

As for my spare time to follow, since my current nitric acid generator has a phenomenal rate of maybe 20 ml/day running full blast, I believe I'm ready to assist in this project in a more hands-on experimental fashion. I still think that we can attain better yields with the improvement of NOx capture after its production in a Microwave Generator (MG). Towards that end, I intend to "pretend" that the plasma arc cutter approximates the output of your MG, and experiment with improving the NOx capture. I will certainly report results. The way I see it, I am ahead of many people in the sense that I have a device capable of doing what the MG will be intended to do, which both relieves me of the need to test, construct and optimise an MG, but also gives me an opportunity to get a head-start on the reclaimation portion of our project.

But anyway, I'll get onto it ASAP. I have some reading on nitrogen compounds to do, as I still think there might be a way to cause the nitrogen to precipitate out; Then I intend to show that distilled water can become acidified when the plasma-cutter gas is passed through.

NBK: I can't think of anything better! (Yet) :(
//Roses are red; Banannas are fruity//
//If I get a bomb; Al Sheik Yerbuti!!!//:D

____________________
EDIT: to add this info:
Radiac Detector
Poloroid No. DT-60/PD, gov't #16-D-19884-1031 dosimeter for measuring cumulative exposure to X- and Gamma- Rays. Still in use today on some older ships according to a naval officer friend of ours, the badge/detector is nonself-reading with a range of 0 to 600 roentgens. They are meant to be scanned by a machine called the "Radiac Computer Indicator CP-95A/PD", which we do not have. Still, a cool bit of cold war history in original military packaging with instructions dated 1951. 1-1/2" dia x 7/16" thick with a 3/4" sq radiophotoluminescent glass inside.
21517 RADIAC DETECTOR $2.00 / PKG(4)

You may not be able to get quantitative measurements of exposure without the reader, but if it gets dark, it's bad!

[Alexires]

Al Sheik - Is that 20ml of 100% nitric acid a day? Because if it is, that wouldn't be so bad.

I will be awaiting your research regarding NOx uptake. It is certainly a part of the project that needs thinking about.

[Al Sheik Yerbuti]

I'm not sure how pure it is, that's debateable. it is fuming, it is orange-red, clear, and yes, 20 ml a day. I should draw out how I do it, but it is a well-documented procedure. Basically, I found two ball-shaped bottles and put KNO3 and sulphuric in one ball, no more than what will not spill out when tipped over (neck horizontal). I tape the empty one on top, starting with teflon pipe thread tape, then electrical tape, then duct tape. Each is important: Teflon resists acid, The electrical seals the teflon, the duct tape holds the rest in place and stops the two bottles from blowing apart from the pressure. The saltpeter/acid side is placed in a sand-filled bowl, on an adjustable heat source. the other bottle is supported horizontally off to the side. I usually have it sitting on an open jar, the mouth suports it well. The two bottles are thermally separated with a piece of cardboard with aluminum foil taped to the hot side. A slit allows the barrier to go around the taped necks. I have three cold packs that I alternate on top of the collection side, two in the freezer and one on the bottle. I cover this with towels to keep that side cold. Never put a cold pack on a bottle that got hot. So keep it cold or turn it off and let it cool if it gets away from you. The heat side, I adjust the heat to maximize the density of the red fumes. There is an ideal temperature range, and above that or below that, the red fumes are not as thick. As long as the cold bottle stays cold, the fumes pass over and condense. Eventually the generation side solidifies and stops making fumes, that's all you'll get. Collect the red fuming nitric after the system cools (the cooler the better), place in airtight glass jar with glass stopper. I didn't have a stopper the right size, so I wrapped some teflon tape around a test tube, held it in place with electrical tape and used that as a stopper. Lather, rinse, repeat. Image below clicks to enlarge.

http://img443.imageshack.us/img443/4982/hno3generatoric6.th.gif (http://img443.imageshack.us/my.php?image=hno3generatoric6.gif)

I guess eveything is relative, 20 ml is excruciatingly time consuming, and I never have enough.

No progress yet on Plasma cutter thing, but I'll go do that here in a few minutes.

[megalomania]

This thread and the "Nitric Acid from Air and Water (http://roguesci.org/theforum/showthread.php?p=88445#post88445)" thread are so similar I am getting confused on what to post in which. Both involve the use of plasma to generate NOx gasses, but produce the plasma in different ways.

The other thread is focused on electric arcs, this thread on other types of plasma generation.

There are two types of plasma that produce NOx gas, high temperature and low temperature. The high temperature plasmas break the molecular bonds of nitrogen and oxygen gas over 3000 oC whereupon the highly reactive free ions quickly recombine with anything they happen to collide be it nitrogen or oxygen. Thus NO is formed, along with original nitrogen and oxygen molecules.

A low temperature plasma like a glow discharge plasma does not use a high temperature flame. Instead it relies on ionizing oxygen and nitrogen between high voltage electrodes. I know what glow discharge is in theory, but I lack practical knowledge of how to use or build such a device. If anyone happens to know of a source of information, I would like to hear it. These should be simple to build, but I can't find any plans or commercial products.

I found plenty of physics articles and alternative energy scammers talking about sketchy info from the 1930's, a very nice website with a decent how-to on making your own telescope mirrors (complete with homemade glow discharge cleaner using a propane tank, but no mention of the glow discharge technology itself), and lots of stuff on sputtering, but no devices.

A plasma torch is a nice idea since it is a commercial package available OTC, but, and this is a big but for many, they are damned expensive. I try to limit my research on materials that are available to the widest possible audience. This is not to say the plasma cutter direction of research is not invalid, the devices are attainable after all, but that only a few will bother spending $400-$1000 for one of these (the cheapest I could find on froogle was $400).

I should qualify that and say few people would be willing to buy a plasma cutter *unless* there was a very clearly worked out method of producing decent quantities of nitric acid resplendent with plans, schematics, pictures, pictures, more pictures, and video.

Anyhoo, I am getting sidetracked from my main line of research, the tungsten catalyzed electric arc process. I admit I have a LOT to learn about high voltage electronics, plasmas, ion generators, and the like. I can see why people enjoy building Tesla coils and Jacob's ladders. I have enough trouble with chemistry to be learning evil physics :)

EDIT: Oops, I forgot to mention the reason for my talking about glow discharge in the first place. US patent 4,287,040 Production of nitric oxides. The invention relates to a process for the production of nitric oxides by passing through the discharge a mixture comprising air and nitric oxide as seeding material, and recovering the produced nitric oxides.

Lets get to the heart of it, the rest is fluff: A flow of air was maintained through a tube of 6 cm length and 2 cm diameter with a constriction of 30 mm length and 3.5 mm diameter at the middle of the tube, the pressure of air entering the tube being 100 torr. A glow discharge was maintained at a current of 0.2 A. The limiting energy yield for nitric oxide formed by the total discharge power was less than 0.55 mole/KWhr. The steady state concentration of the nitric oxide (NO) produced by the discharge was about 6 percent.

About 5 percent of the mixture leaving the discharge tube was reintroduced into the discharge tube at its entrance, and thus this passed again through the discharge plasma with air introduced. An increase of about 10-20 percent of yield was obtained by this seeding with nitric oxide.

Ahh, there is the rub, a glow discharge plasma is used. The point of this patent is to inject NO gas into the discharge zone to act as a non-ionizing gas that increases the efficiency of the unit. I don't know how they expect to keep the NO from reacting with oxygen and forming NO2 before it is injected back into the plasma.

If I was doing this I think I would recycle the NO gas given off by the reaction of NO2 with water which forms NO and nitric acid. Of course that assumes I can figure out how to continually add more air and draw off the NO without creating a closed system. Hmmm...

[Alexires]

Al Sheik - While your method is dubious (its found in the Anarchists Crapbook afterall), you could always work out the % using the density...

Edit: Mega got a post in before I clicked the button.

http://jnaudin.free.fr/html/s_gdp1.htm

This is a website on making a Glow Discharge Plasma Panel.

As I understand, glow discharge plasma is simple where there is such a high voltage difference that the air is ionised. This can sometimes be observed on transformer boxes outside your house. A blue haze sometimes hangs around them.

Interestingly enough, I found this (http://www.iop.org/EJ/abstract/0022-3727/27/4/018).

It states that NO2 decomposes when passed through a low pressure glow discharge plasma.

Mega, Here (http://science-education.pppl.gov/SummerInst/SGershman/Structure_of_Glow_Discharge.pdf) is an interesting PDF on glow discharge phenomenon.

[Al Sheik Yerbuti]

1) I will certainly do my best to verify my findings and use rigorous scientific methods to conduct my experiments.
2) YIKES! I had no idea that my method was in the AC. I don't believe I have even read it, although I have certainly heard of it. Do you happen to have a link to it lying around conveniently? I would be interested in that take on this method.
----------------------------------
EDIT: Oh, you mean the two-bottle and the sulfuric and saltpeter method? I thought you meant the plasma cutter thing. Hell yea, this method is certainly effective. I got my initial information on this method from a US Army Field Manual, FM-31-210. I have been playing wit it for a while and have improved it for my convenience and efficiency. As a matter of fact I now have reason to believe that the purity is so high that you might have to ADD water to get HNO3. That is discussed in the other thread.
4)The efficiency of this double-bottle method is why I am interested in capturing our enriched NOX emissions from plasma discharge methods in a chemical manner, such as KNOX as opposed to in a solution of water. I took the bypassing of distillation and drying stages of HNO3 to be obvious, if we could make pure saltpeter from Potassium Cloride and electrified air. My mistake, so I'll mention this explicitly: If we can capture our NOX (which is produced by some type of electrical burning of air) by making chemically pure SOLIDS such as KNO3, there are proven methods for the production of NO2, which I take to be anhydrous Nitric acid. NO2 can be condensed at ~20 Celsius and reacted with H2O to make HNO3 of a purity and concentration exceeding the requirements of our needs.
EDIT 2: I added a drawing to my post above (#48) which visualizes the description contained therein. END EDIT #2
5) I agree that these threads are blurring. Some of that is my fault, I apologise. OTOH, maybe it could be straightened out, but it might not matter so much, in the long run.
END EDIT
----------------------------------
3) My main interest in using a plasma cutter in this manner is because I happen to have one. For me, it is a shortcut to the end result of verifying the efficacy of the method. I can, basically, cut to the chase and verify the theoretical, saving time and money for some to build a device only to find that the theory is in error.
3b) As I have posted in the other thread, I have had some encouraging results and will pursue improvements in efficiency.

[nbk2000]

The 2-bottle distilling setup is one of the few things they didn't fuck up in the AC, probably because they got it from the first Black Book.

It's crude, but it works.

[jpsmith123]

It seems that the question of whether a glow discharge tends to make NOx, or to get rid of it, depends on the so-called "electron temperature" of the plasma which I guess is a measure of the power density of the plasma.

It seems humidity is a factor also...at least in a dielectric barrier discharge plasma.

A dielectric barrier discharge might be another way to go. Here is a paper that talks about it a little bit.

http://www.alexchirokov.narod.ru/Presentations/France_ISPC_Oral_FrOral_AUG_2001.pdf

[Chris The Great]

You'll need to use a potassium base, such as hydroxide, carbonate or bicarbonate, to get KNO3. KCl will not form KNO3 when exposed to NO2. However, the base might also form nitrite (KNO2) by reacting with NO and NO2 before the NO can be oxidized by the air... I couldn't say for certain at all how much of a problem this would be.

[Alexires]

I think that the go for removing NO2- ions from HNO3 is to add H2O2 to the acid, hopefully oxidising the xNO2 to xNO3.

Interestingly enough, I found this.

http://www.rsc.org/publishing/journals/CC/article.asp?doi=b609005b

It describes catalysing NO2 + water into Nitrous Acid via irradiation from illuminated titanium dioxide.

Also, found this (http://pages.towson.edu/ladon/orgrxs/reagent/oxidizer.htm). From my understanding, it alludes that Nitrous Acid can be used to oxidise amines and amides into N-nitroso compounds, as opposed to nitric acid, which cannot. So possibly the addition of an amine or amide could remove Nitrous Acid impurities in Nitric Acid. I don't really know about that, someone with more knowledge than me might be able to verify it.

Ahhh, just read Chris the Great's post on the other thread.

Mega, maybe we could join these two threads in the Special Project Section under Nitric Acid? Maybe under Plasma production method of HNO3 or the like?

[Meawoppl]

I can now make BIG sparks in the microwave, with relative ease. After an hour or so of playing with the setup myself and a friend were informed my my room mates that it was making a terrible smell? We had no idea that there was a smell, does NO/ NO2 do that?

[knowledgehungry]

Yes. NO2 certainly makes an unpleasant smell.

[nbk2000]

Could also be ozone.

But, regardless of what it is. it's not healthy for you to be breathing it in.

During experiments in the production of toxic gases (NOx or O3), you MUST have adequate ventilation to prevent any exposure, as damage is cumulative and irreversible.

[FUTI]

If the smell was of the kind you sense near photocopying machine...that should be ozone.

Some of those bioionizator gadgets make small quantities of ions (and maybe little ozone too). Is it a "far cry" to expect that this device can provide some kind of "priming mixture" for microwave to ignite the plasma more reliable?

Guys these two threads that we have about the HNO3 production by other means are so close in my mind that if by chance I posted in wrong thread I do apologize but in my mind they start to look like Matrix clones.

[Meawoppl]

The trickier question that I was getting at was why would we not smell anything? Did we possibly saturate some chemical smell receptors? Is that a known behavior of O3 or NOx etc?

[chemdude1999]

Meawoppl, after using an ionizing air cleaner for a few years (before I realized they have some drawbacks), I would say ozone can dull your olfactory senses.

For example, after coming into my old apartment with the cleaner running full tilt all day, the ozone was very apparent. Distinct smell/feeling. However, after as little as an half hour, the smell/feeling would be much weaker. Like I would get use to it or something.

Visitors would vouch for this as well. Now, I'm not sure on NOx. Just something to ponder.

NBK's advice to always have adequate ventilation is the safest approach. Take care of the lungs and open a window at least, do it outside, or make a fume hood.

[mr.pyro]

I do believe it was ozone we were creating. I noticed that the smell in the beginning of the arc process was similar to smells I have previously smelt while arc welding. It makes sense that we are going to produce the same gas with a similar electric arc. A wikipedia/google search on gas produced while welding returns mostly ozone and small quantities of NOx and other trace gases. I did not smell any kind of NO2 during this experiment like NO2 produced during a nitration reaction so I think we hardly produced any of this at all.

It seems there is a simple test for ozone concentration that might be worthwhile.
http://www.achooallergy.com/acc-ozonewatch.asp

[nbk2000]

Many toxic chemicals can be smelt at first, but then olfactory fatigue kicks in, and you keep breathing the toxic gas because you no longer smell it, thinking it somehow magically disappeared.

If you smell it when you first get exposed to it CLEAR OUT! Assume the gas is strong enough to kill you, and take appropriate measures to ventilate the area.

This same situtation of olfactory fatigue happened to me with H2S. I was using it in a synthesis and smelled a sulfurous smell, but it 'magically disappeared', and I continued on. An associate came in and complained about the nauseating stench, telling me it was building up!

[hydra]

As far as using the MIG for this job, it is completely unfeasible. As stated earlier, it only produces around 27V and requires a current sink (the workpiece) to maintain the spark. snip

Now on to the plasma cutter: I can promise you I know more about its operation than a tiny article in "HowStuffWorks" could convey. That borders on insulting, Alexires. (But you're still my buddy) I am assuming that everyone is able to see the photo that I posted in post #40? The image shows the hot gasses being ejected into the atmosphere, quite clearly in a plasma state. The particular unit that I own has, as I said, an internal air pump and shoots this stream of air up the hose, and through the electrode where it is heated and charged and ejected in a plasma stream. This is in fact the device most likely to produce results for us. I believe this device WILL work. The welders are too low of voltage and infeasible to modify to our end. IOW they will NOT work.
snip



Until now, I have avoided posting in the Nitric Acid threads, despite a 'burning' desire :D to do so, because I have not yet done the experiments.

However, having a 30-year background in power-electronics, including arcs and plasmas for industrial processing, the arc/plasma method for Nitric is something I've studied in some depth over the years.

The above-quoted post requires a response, and I've been wanting to add some suggestions to the project anyway; so I am going to go ahead and post, despite not yet having done the trials myself...


First, the above info on Plasma-cutters is incorrect. What he is seeing is the "pilot arc". In fact, in terms of current-path, the plasma-cutter ISN'T any different than the MIG. The MAIN current does in fact go -through- the plasma stream into the workpiece (the plasma stream is a good conductor).

Sheik, if you think about the fact that you must connect the 2nd lead of the plasma-cutter TO the workpiece with heavy-gauge wire and ground-clamp, you will understand that this connection is for closing a high-current circuit which is THROUGH the workpiece.

Again, when you hold the torch in the air, away from the workpiece, and see that hot jet coming out, that is the PILOT arc; not the 'main' arc.

For anyone interested in plasma-cutters, I suggest studying one of the seminal patents in the field, from way back in 1955:

WELD-pat2806124- ARC TORCH AND PROCESS - RM GAGE.pdf

Nicely, it also happens to be one of those few patents which are REALLY well-written; and with lots of specific "real data" given.

Gage was with Union-Carbide, i.e. Linde....the firm which also came up with TIG-welding originally.

In fact, one of the interesting things you'll note upon careful examination is that, for this seminal work on plasma-cutting, he is USING a regular TIG power-supply!

In other words, the voltage is NOT critical; and in fact a MIG power-supply could be made to work. It is not optimum though; for two reasons.

First, higher voltage does help; in that it gives you more freedom to increase plasma-stream/arc length between electrode and workpiece.

But far more important is that a MIG supply is a constant-VOLTAGE supply; and it is difficult to produce STABLE plasmas with a voltage-source. You want a constant-CURRENT power supply; i.e. a supply which varies its own voltage as needed automatically; in order to maintain a constant current.

Note; A MIG supply can easily be changed to a current-source by insertion of an impedance in series with it; i.e. a resistance (wasteful) or an inductance.


FYI, a typical modern plasma-cutter runs around 250-300vdc OPEN circuit; falling to 50-150vdc (depending on conditions) when the arc is struck. My ESAB PCM-750i runs about 120v when it's set to 50 amps.

Typical constant-voltage (i.e. MIG) welding supplies run about 20-30vdc during arc; without much increase at open-circuit; perhaps to 30-50vdc OC.

Constant-CURRENT arc-welding supplies (i.e. for TIG and stick) also run 20-40vdc under full load; but rise to 60-100vdc open circuit.

Note that a plasma-cutter and a regular (i.e. stick/tig) power-supply are both constant-CURRENT type supplies. I.e., current-source vs. voltage-source.

Note also that the voltage during arc is highly dependent on the arc-LENGTH; among other variables/conditions.

fwiw, I designed such PWM inverters (and motor-drivers, switching power-supplies, etc) for a living for many years. I currently have two ESAB plasma-cutters, a Miller Dialarc-HF 300 TIG welder, a Lincoln Weldanpower-225 engine-driven stick/MIG in the yard-truck, an engine-driven Miller Trailblazer 450 amp MIG/stick for "the big stuff" :D , and a couple others sitting in the storage-trailer that I can't even remember right now... :rolleyes:


I did not like to read of Sheik's failure to detect pH change with his plasma-cutter experiment; because I have expected this machine to be PERFECT for a high-production Nitric-acid plant for us.

I am not sure why his experiments didn't work out yet; but I do plan to continue fabricating and testing such a plant here. I still believe a plasma unit to be an excellent foundation for such a plant.

(also any old DC stick-welding supply; so there shouldn't be a need to drop big bucks on a plasma-cutter if you don't have one; although they are DAMN handy to have around... :D )


Part-2: Supersonic Expansion

Last night, I did a forum-search for "supersonic" and "nozzle"; expecting those to have been discussed here already. Surprisingly, I've found no mention of them in regards to Nitric; so I'll go ahead and introduce this concept; because it was a key aspect of the later Nitric patents which were concerned with -efficiency- of the process.

As noted elsewhere in these nitric threads, the nitrogen oxides at very high temps want to go back to being oxygen and nitrogen. One of the best ways to prevent this is to chill the arc-output gas. The faster you cool it, the more NO2 is retained as product.

The best way to chill a gas quickly is not by refrigeration, but via expansion.

I believe it has also been shown/mentioned that the best way to improve production of the oxides is by raising the pressure.

These may sound conflicting, but they can actually be -complementary-.

An excellent way to achieve both desirable conditions in the same apparatus, is to use a supersonic, or DeLaval, nozzle at the heart of the process. This type of nozzle, by design, is fed with high-pressure, produces a supersonic zone/shockwave in the throat, and then rapidly expands the gases at the exit; thus achieving exactly what we want, to wit:

- high pressures in the hot reaction-zone

- extremely high cooling-rate within microseconds/centimeters of the oxidation reaction occurrence/zone.

My (still unbuilt/untested) design replaces the 'standard' plasma-torch with a machined copper Delaval nozzle which, unlike in a regular plasma-cutting setup, WILL take the entire arc-current. The power-supply will have to be run at a minimum current-setting to avoid rapid overheating and erosion of this nozzle. Even so, this setup is likely to only work for short runs; but that should suffice for testing the viability of the process.

If the process works properly, I will then fabricate a double-walled version, to provide for water-cooling.

Note that a typical "plasma cutter" gives us a base to work with which is both constant-current, and designed to process gas at about 4-10 atm. So it's indeed a good place to start, in my opinion.


Further on Arc Control and Nozzles:

Also, many designs of arc/plasma electrodes in various applications provide for turning the gas-flow into a vortex as it passes through; which spreads the arc around the entire surface area of the nozzle/electrode; which prevents melting/erosion of the surface at any one spot.

(normally, an arc WANTS to stay at the spot it first strikes, as that area instantly becomes surrounded with vaporized metal ions which makes it the easiest place for the arc to jump to / continue at.)

One can also use EM forces to continuously move an arc along an electrode. I found this patent particularly interesting and relevant...

PLA-pat2964679-ARC PLASMA GENERATOR - Moving Arc Saves Electrodes - SCHNEIDER.pdf

(these guys crack me up....the performance graph in that patent runs from 2,000 to 20,000 amps of line-current! those guys don't fuck around... :D )

This one is also worth looking at:
DIR-pat3400070-HIGH EFFICIENCY PLASMA PROCESSING HEAD with DIFFUSER with EXPANDING DIAMETER - Naff.pdf

Now that I think about it, it may be helpful to add a list of relevant and semi-relevant patents to the end of this. These are all patents that I have read and found worth saving and annotating. (Mods: if including the patent-list is inappropriate here, please edit/delete, and let me know for future ref.)


In summary:

1) ANY power-supply will work; including MIG if that's all you have; but a constant-CURRENT source is much preferred; and a higher-voltage supply gives you more options. While a plasma-cutter supply is likely best, and will indeed be the basis of my first experiments; an old DC stick-welder is also constant-current, has a reasonably high open-circuit voltage, and should be workable for a production plant. However, I can't verify this as known-fact until having done the experiment myself.

2) Superfast cooling of the reaction-products preserves more of the hard-won oxides. Supersonic expansion is one of the best/easiest/cheapest/simplest ways to achieve this super-fast cooling.

3) The generation of plasma via RF fields (e.g., microwaves; but actually you can use other freqs too) is also a viable route. The patent-list below was selected via "plasma", so will include some patents of relevance to the RF route as well.

4) Arc and glow-discharge are two different things; but both types of plasma are very "hot", in the energy-level sense. For those interested in the non-arc routes, I suggest research into ICP or "inductively coupled plasma", and "electrodeless discharge". Note that virtually all "glow discharge" situations require pressures BELOW atmospheric. This does not sound optimum for NO's production; although such a plant may involve other factors which make the low-pressure unobjectionable.

ps; there areways to make a "glow discharge" stable at 1-atm, in somewhat limited situations. Again, the list below contains a few items relevant to this.


I hope this post clarifies the situation somewhat regarding power-supplies for "plasma processing"; and also introduces some additional concepts which are ripe for further discussion and experimenting.


ps; Mega, I was going to address your questions about resonant-cavity design too; but this post has gotten so long already; that I'll leave it for another time. Suffice it to say that ALL cavities have "antinodes"; and that cavity design/construction can be a relatively easy thing. I have made numerous cavities from 1/2"-3" copper water pipe. This material is also very easy to work with, fabrication-wise; e.g. for water-jacketing, gas plumbing, etc. etc.. fyi, a few of the patents in the list below deal with cavities.


List of A Few Relevant Patents:

CH-pat5397961-Apparatus for generating a pulsed plasma in a liquid medium.pdf
CH-pat6471932-Plasma-Catalytic production of Ammonia from N2 and H2O.pdf
CH-pat7037484-Plasma reactor for cracking ammonia and hydrogen-rich gases to hydrogen.pdf
DIR-pat3248446- PLASMA STREAMS AND METHOD FOR UTILIZING SAME - Applied Physics.pdf
DIR-pat3400070- HIGH EFFICIENCY PLASMA PROCESSING HEAD with DIFFUSER with EXPANDING DIAMETER - Naff.pdf
DIR-pat3429691- PLASMA REDUCTION OF TITANIUM DIOXIDE - Mclaughlin.pdf
DIR-pat3694618- HIGH PRESSURE THERMAL PLASMA SYSTEM - Poole.pdf
DIR-pat3862393- LOW FREQUENCY INDUCTION PLASMA SYSTEM - Dundas.pdf
DIR-pat4361441- Treatment of Matter in Plasma-Rotating 60hz Arc - Tylko.pdf
DIR-pat4680096- Plasma smelting process for silicon - Dosaj-DOW.pdf
DIR-pat4745338- Electromagnetically sustained plasma reactor - Hollis.pdf
DIR-pat5039312- Gas Separation with Rotating Plasma Arc Reactor - Hollis.pdf
DIR-pat5147998- High Enthalpy Plasma Torch - Tsantrizos-Noranda.pdf
DIR-pat5200595- Induction Plasma Torch Water-Cooled Ceramic Confinement Tube - Boulos.pdf
DIR-pat5288969- Electrodeless Plasma Torch for Dissociation - Wong.pdf
DIR-pat5630880- Large Volume Plasma Processor for Any Feedstock - Eastlund.pdf
EB-pat2902614- ACCELERATED PLASMA SOURCE.pdf
EB-pat3648015-Fairbairn-RF GENERATED ELECTRON BEAM TORCH.pdf
PCB-pat4618477-Uniform plasma for drill smear removal reactor.pdf
PLA-belljar.net_plasma.htm.pdf
PLA-ESAB-pat6346685-Plasma arc torch - Improved Sealing.pdf
PLA-pat2964679-ARC PLASMA GENERATOR - Moving Arc Saves Electrodes - SCHNEIDER.pdf
PLA-pat3004137-Producing High Gas Temp by Flowing Flame through Plasma.pdf
PLA-pat3278796-MAGNETICALLY CONTROLLABLE PLASMA FLAME GENERATOR.pdf
PLA-pat3577207- Microwave Plasmatron.pdf
PLA-pat3619403-GAS REACTION APPARATUS-Oxygen Plasma- Gorin-LFE.pdf
PLA-pat3641389-HIGH-POWER MICROWAVE PLASMA DISCHARGE LAMP - Leidigh-Varian.pdf
PLA-pat3790742-Plasma Torch Head - Auer.pdf
PLA-pat3903891-GENERATING PLASMA 1-atm - maybe Torch - Brayshaw.pdf
PLA-pat3911318-High Power UV-Vis from Plasma- Spero.pdf
PLA-pat4129772-Electrode structures for high energy high temperature plasmas.pdf
PLA-pat4883570-Reentrant Cavity for 10x Lower Freq - Chemical Processing in Atmospheric Plasmas - Efthimion.pdf
PLA-pat5069546-Atmos pressure capacitively coupled plasma spectral lamp- for AA.pdf
PLA-pat5122713-Atmospheric pressure capacitively coupled plasma excitation source- for AA.pdf
PLA-pat5131992-Microwave induced plasma process for producing tungsten carbide - Church.pdf
PLA-pat5274306-Capacitively coupled radiofrequency plasma source - Kaufman.pdf
PLA-pat5414235-Gas plasma generator with resonant cavity - Lucas.pdf
PLA-pat5414324-One atmosphere, uniform glow discharge plasma- 1-100khz.pdf
PLA-pat5534232-Apparatus for reactions in dense-medium plasmas.pdf
PLA-pat6232723-DC Plasma discharge via Liquid-loaded Porous Nonconductive Electrodes.pdf
PLA-pat6416633-One-Atm-Resonant excitation for generating plasmas - Spence.pdf
PLA-pat6686558-Atmospheric pressure inductive plasma apparatus.pdf
PLA-pat6771026-Plasma generation by mode-conversion of RF-electromagnetic wave to electron cyclotron wave.pdf
PLA-pat6982395-Plasma Welding with low jet angle divergence - Bayer MTU.pdf
PLA-The Brush Cathode Plasma--A Well-Behaved Plasma-NIST966.pdf
PLAS-pat3597650-ARC RADIATION SOURCES-like Plasma Torch.pdf
PLAS-pat5977715-Handheld atmospheric pressure glow discharge plasma source.pdf
PLAS-pat6217776-Centrifugal filter for multi-species plasma.pdf
PLAS-pat6923890-Chemical processing using non-thermal discharge plasma.pdf
PLAS-pat6936144-High frequency Plasma Source.pdf
SF-Co-Gen of C2 HCs and SynGas from CH4 and CO2 using Dielectric-Barrier Discharge Plasma Reactor without Catalyst at Low Temp.pdf
SF-Istadi-CoGen of SynGas and C2+ HCs from Methane – CO2 in A Hybrid Catalytic Plasma Reactor-Fuel2006.pdf
SF-Istadi-CoGeneration of C2+ Hydrocarbons and SynGas from Methane and CO2 using Dielectric-Barrier Discharge Plasma Reactor without Catalyst at Low Temp.pdf
SF-MIT-pat6322757-Low power compact plasma fuel converter- Cohn.pdf
SF-pat5626726-Cracking Hydrocarbon Liquids w Submerged Reactive Plasma - Lockheed.pdf
SF-pat6159432-Plasma Conversion of gas streams containing hydrocarbons.pdf
SF-Plasma Quench Process for Natural Gas-10119388.pdf
VAC-Ion-pat6824363-Linear inductive plasma pump for process reactors.pdf
VAC-pat4641060-Electron cyclotron heated plasma for vacuum pumping - Dandl.pdf
WELD-pat2806124- ARC TORCH AND PROCESS - RM GAGE.pdf
WELD-pat3555234- PLASMA ARC METAL MACHINING - Ilya Shapiro.pdf
WELD-pat3567898- PLASMA ARC CUTTING TORCH - Irwin.pdf
WELD-pat3641308- PLASMA ARC TORCH HAVING LIQUID LAMINAR FLOW JET FOR ARC CONSTRICTION.pdf
WELD-pat3809850- Plasma Arc Power System w Separate Pilot Arc Control - Carbide.pdf
WELD-pat4943699- Power Supply for Both Arc and Plasma -Thommes ITW.pdf
WELD-pat4977305- Low Voltage Plasma arc cutting - Severance-Ltec.pdf
WELD-pat5086205- Using Welding power supply for Plasma Cutting - Thommes-PowCon.pdf
WELD-pat5558786- High quality Plasma cutting of Stainless and Aluminum - Couch-Hypertherm.pdf
WELD-pat6037566- Reduced Cost Arc and Plasma Power Supply - Yasuhara - Panasonic.pdf
WELD-pat6313431- Plasma cutter for auxiliary power output - Schneider ITW.pdf

[megalomania]

Now that is what I call a quality post :) You are indeed spot on about the need to rapidly cool the resulting NOx gasses after formation. The reaction is in equilibrium at high temperatures, so cooling them will increase yields. I am not familiar with the technology of supersonic nozzles, but I understand the principle, and they sound like the perfect solution.

Increasing the pressure will not only force more reactant into the finite space of the plasma, but it should also shift the equilibrium away from free nitrogen and oxygen ions and towards ozone and nitrogen dioxides. There would be no equilibrium benefit to be gained in forming NO from nitrogen and oxygen diatomic molecules because it is still forming an atom per atom molecule, but ozone and NO2 are favored because they have 3 atoms per molecule. In theory, a rather large percentage of NO should form because the percentage of nitrogen is so much higher than oxygen that it can’t help but recombine to form nitrogen oxides and nitrogen. The faster the products can be cooled, the higher this yield should be thus avoiding the inherent instability of NO at high temperatures. I suspect the thermal decomposition of nitrogen dioxide is the reason why yields of only a few percent are obtained.

This is certainly turning into a serious project, but with all of the equipment available to the consumer, and all of the technology being “off the shelf” I can see this becoming a formidable tool for the home, farm, and small business production of nitric acid or nitrogenous fertilizers.

A patent list is perfectly acceptable. Please, keep them coming.

[Nitric-producer]

Hydra, do you have a drawing or something of the expansion nozzles you described, after reading through all the "plasma" threads, I realised it could improve yields a good bit on all our "plasma reactors"!

Just want to say well done to everyone slaving away on projects like this. I feel we are starting to make a lot of progress now. After reading this thread with great interest - I really want to go buy an old microwave! :D

[hydra]

mega, thanks.

Nitric: Here are a couple of excellent DeLaval design pages:

http://members.aol.com/ricnakk/th_nozz.html

http://www.engapplets.vt.edu/fluids/CDnozzle/cdinfo.html

That 2nd one even includes a design-program applet.

Considering the mass-rate and input pressure we're likely talking about (i.e. both pretty small), I'd guess that a nozzle for our app will be quite small; and with a tiny throat.

It should be easily machineable on any small lathe. Not that gooey copper is all that much fun to machine... :D

Another alternative would be to grind a drill to profile; and simply drilling the part to shape.

Note: in our app of course, there's no need to machine the -outside- to profile. That's only done in aerospace apps to reduce weight. Instead, one might look at drilling holes around the periphery as cooling-water channels; and in fact including nozzles at the outlet-end; where the spray/steam would exit and be entrained with the rapidly-expanding NO flow.

As I understand the process, the sooner the NO's are in contact with water, the better. Can't get any sooner than this. :D

Drilling deep small-diam holes in copper will not be fun; but an alternative would be to go ahead and turn down the outside (does not have to be to any particular profile though), then machine a shell and braze that on, to form a double-wall structure. Add the tiny exit-spray nozzles in the end-plate.

Note; there are a number of copper -alloys- available; which may be much preferred for this application. The one I have in mind right now is a copper-tungsten alloy intended for machining spot-welding electrodes from.

As I recall, it's about 7-8% tungsten; and is considerably harder and stronger than pure copper; while giving up about 20-30% of conductivity.

Worth looking into.

By the way, the MSC catalog (which is HUUGE) lists all sorts of interesting materials for sale...including this alloy...and including things like screen (mesh) in many different materials, including stainless. They also have graphite, as I recall. Anyway, that's a catalog that's well worth having on the shelf.

This nozzle assy will be somewhat of a project, no doubt. But it has the potential to perform virtually every important and desirable HNO3-gen function, in an optimal way; all in one part. So I intend to pursue it at least to the proof-of-concept stage.

[webuyhouses]

Regarding the price of microwave ovens, I have had great success obtaining used ovens by searching the trash.Try apartment buildings, or trash collection night in neighborhoods. This is in the USA, and I assume it is true anywhere.

Most if not all of the ovens I found this way have worked (I must have sold 20+ for scrap metal) If they don't, check the fuse, or just energize the primary side of the big transformer. I have never seen a magnetron go bad.(from cooking food;) ) Worst case is the timer control burns out.

Also, the magnetron is powered through a half-wave rectifier. Tne post had mentioned hard-wiring the magnetron to operate continuously. I haven't tried this, but the way to do it would be replace the single HV rectifier diode with a 4-diode full wave rectifier (from 4 ovens). This will still have a power dip at 120Hz, but possibly adding a much larger capacitor will be able to smooth it out. (I figure it would have to be around 4kv, 100millifarad compared to the oven's .68-ish millifarad one.) Keep in mind that this will more than double the average power input to the magnetron. From what I've read, reflected power tends to be more destructive than absorbing all the available power, so careful design of the rest of the device will be important to keep it cool.

I just tried an experiment to reliably ignite a plasma ball. I whacked out a spot in the door frame so I could stick in the leads from a 5kv NST, taped so that the arc would switch itself on. Switching on the transformer and the oven resulted in some unstable plasma, and the wires melting VERY fast.

[Thermiteisfun]

http://www.emanator.demon.co.uk/bigclive/ozone.htm
This makes quite a bit of ozone, a few of the other things on his site are pretty interesting

[megalomania]

I get a 404 error visiting that link... They have a homepage, but no links to anything else at all.

EDIT: There it is, ozone.htm

It's .htm NOT .html

[Nitric-producer]

Been doing some research on this lately. With regard to Mega's post on page 3 (post 24), the diagram of a plasma torch, I believe that most of the workings are overly complicated for the average home user. Most of the eccentricities of the design are used for ignition of the plasma ball :confused: .

A simple torch would consist of a magnetron coupled to a waveguide, (basically a rectangular metal tube) and the waveguide attaching to a glass tube (pointing upwards) with air blown through it. To ignite the plasma inside the glass tube, would however require a high voltage discharge across the airflow.

I would assume that (with my limited knowledge on waves and plasma), a plasma would form inside the tube and remain there after the high voltage discharge stopped?

I have a neon sign transformer which would be perfect for the high voltage discharge. However I have no idea if this would work at all :p

[gaussincarnate]

Unfortunately, my experience with plasma is much more theoretical than I would like. I can tell you, however, that the exact configuration detailed in Mega's patent is not exactly experimenter friendly. Microwave resonance cavities are made out of niobium-Yb alloys in a clean room. They are rolled on CNC lathes (spinning, not cutting lathes) and welded with electon welding beams. The smallest sharp protrusion (dust, a burr, etc.) causes a catastrophic meltdown due to arcing and instantaneous generation of very, very high currents. One of the largest manufacturers of MRCs (fnal) makes, on average, one a month. In other words, I would not suggest this method.

I would however, suggest trying to form the plasma out of pure nitrogen and accelerating it towards a tank of water at the other end. Naturally, unless you feel like making a superconducting accelerator, the majority of your velocity will come from the nitrogen imput nozel. Luckily, N has a rather favorable charge to mass ratio in plasmas, meaning that an electric field will do a great deal to accelerate it. Although it may sound rather complicated, I believe (more accurately, hope) that a simple N plasma in a tube directed downwards into a tank of water with a very positively charged electrode at the end should suffice. That is, of course, assuming that a very high velocity nitrogen ion will rip the hydrogen off and form nitrogen oxides that would be instantly converted into nitric acid. It may be a long shot, but if it doesn't work, it could still be used to silence neighbors. That would be a unique threat; "If you don't get your dog off of my lawn, I will shoot it...with high-velocity nitrogen ions. HAHA I will give yor dog cancer. In eight years."