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Author: Subject: Birkeland-Eyde reactor for making nitric acid.
hissingnoise
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 Quote: That's it for not the wife calls :-)

'Some nice stuff, o442 ─ you can, BTW, monitor operation of the arc on FM radio and your close neighbours probably can too . . .

And IMO, aluminium welding rods make ideal electrodes for a travelling arc!

offset442
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Actually I swear I can hear the arc manifest in the eddie current fluctuations in my ceiling fan, when up late at night unable to sleep. :-) I can clearly hear the arc starting, expanding and the small resonate kick from it breaking, this is where I feel some sort of soft switching supply with an uber dc line filter would be nice to have, I could not imagine the effect of a mot system on residential power, without such a device, perhaps soft switching microwave ovens will become more common in the near to not near future. I'm sure is would corrupt smart meter data points at the very least, which is agreeably a positive effect

My preference for1/4 inch steel round bar because the formations of ferrites actually have a small catalytic effect in breaking N2 (read harber) not to mention the electrodes can be easily welded to the heads of 1/2 inch bolts making for nice seal able lug connections. Also it is very advantageous for maintenance as the start gap can be adjusted with a few hits of the mig gun and then an carbide rotary bit.

My rig has been running for almost a year now, happily?? making me as much acid as I can use, mostly the lessons that I have learned, as most the concerns about absorption are impractical to consider on a lab scale , I simply vent the waste NO to the outside, and I can't even smell it where is comes out next to lab door unless it has reached 40% this is uasly the que I use to know when to change out the bottles.

Secondly over restricting the gas flow with bubblers has a negative effect allowing the n2o concentration to build to above 2% has resulted in delayed production, so gas flow should be such that the no2 concentration is maintained at about 50% of ultimate concentration judged colormetricaly against a bone white background as a practical means. As you have a setup running for a long time these little things become obvious.

Bubblers are made from cheap/poorly sintered/easily abraded, coarse grit alumna bench grinding wheel, with hole drilled with hss drill bit in the wet, very slow rpm high pressure, reshape bit as needed on bench grinder, use chisel then bench grinder to shape stone as well, stone is then glued to glass tube using clear PVC cement with 60 mesh screened crushed glass, apply cement, roll/sprinkle glass, air dry to tackey replete, cure at 50 C for 24 hours, coating shrinks, holds up well, untouched after 1 year.

STD 1 outlet aquarium air pump works good, one for deep aquariums might be better.

Final scavenger bottle needs to be twice the volume of 40% bottle.

To harvest empty 40% bottle, refill from scavenger bottle, then add di-water to scavenger bottle, scavenger bottle should not be allowed to proceed beyond 15%
Which is not a problem as long as its twice the volume of the absorption bottle.

I preference is to check concentration using a graduated cylinder calibrated with 200 grams of di-water, found graduation to be 7ml off off re marked 200 mil line:-) , weigh 200 ml acid divide weight by 200, then calculate density or just d/l a nitric acid density chart like I did print it out and post on cabinet door.

That's what I got enjoy :-) sorry form the typos my tablet is a pia to type on.

[Edited on 22-10-2012 by offset442]

[Edited on 22-10-2012 by offset442]
chucknorris
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Hey,

Im looking for a transformer for my reactor now. Im using two 500mm by 4mm tungsten electrodes, and looking for transformer that can deliver 10-20kV with 300-150mA (3kW max load). I will also look for smaller voltages with higher amperes.

[Edited on 15-11-2012 by chucknorris]

[Edited on 15-11-2012 by chucknorris]
offset442
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up scaling

"Im looking for a transformer for my reactor now. Im using two 500mm by 4mm tungsten electrodes, and looking for transformer that can deliver 10-20kV with 300-150mA (3kW max load). I will also look for smaller voltages with higher amperes."

IMO tungsten is a waste of time, its too small, and you cant weld it to anything, solid steel bar holds up for a long time and can dissipate more heat, as well when you use a minimum start gap, meaning the smallest gap you can set before the air pressure your using cant blow the arc to at least 80% of the total ladder height. you will indeed go very long periods of time between making gap adjustments

sounds like you have some problems to solve I highly recommend that you read this book before you proceed with such a large machine:

The Fixation Of Atmospheric Nitrogen (1914): Joseph Knox it is available in full freely on Google books

this book talks about most all of the methods used to produce nitric acid from arcs, at the turn on the 19th century this was very high tech, hard to do stuff, today with modern electronics, now days you can almost use 6-8 Mazilli ZVS flyback drivers running at 500 watts each from tv flabacks installed in a pool of heat sink cooled mineral oil to get 3kw and 10-20 kv. it merely comes down to the questions: how well can you weld and fabricate? Do you have all the required tools? can you do it without hurting yourself? all very important questions

for a mot scale design you will have to get very creative, you will need effectively get rid of 3kw of heat, you know thats how much the water heater in your house uses right? this means that you will need to use an old 50cuf oxygen cylinder to use as a nice bit large O.D. piping, a glass porthole of some sort to check the arc gap, sealed with red automotive silicone, and a nice pice of machinable ceramic or thick high temp thermo plastic such as kevlar or the like to use as a base, sealed with a high temperature silicone mat as a gasket with some sort of compression device using bolts to hold it closed. this covers your basic pauling furnace easy to build and efficient requires occasional tuning of the start gap (haven't had to re-tune mine yet) use 3/8 inch round bar and a ceramic base and you will have zero problems

the second option is to take an aluminum, titanium, molybdenum, niobium, zirconium (something nitric acid resistant, heat resistant, and NON-MAGNETIC sphere, ( probably have to gnd the sphere and wrap it in water fed copper tubing) and place an air cooled stainless ball in the center, on a ceramic isolator (cabinet knob) now surround the sphere with some intense electro magnets, use an arc starter to get the arc going over the relatively large gap, then blow air through the sphere until the arc quenches and dial it back a bit. You did remember to tangentially drill it right so it makes a vortex?

now vent air at a single port 90 degrees from the tangential plane, this no2 laden air needs to be vented through an all aluminum condenser such as the kind found in a freezer with a fan mounted to it such as that found on a car radiator, I know i keep saying aliuminum, i know its a bit crazy however can you afford a stainless heat exchanger? maybe alternatives to occasional scraping another refrigerator could be an Allan spiral condenser.

now onto your absorber i have found that calm surface area is almost as fast as bubbling so on this scale you are going to have 3 options really, trickle towers which require pumping and spraying the absorbent down a vertical section of pipe over perhaps some surface area generating medium say aquarium glass beads or marbles. another option bubble caps : see google or lastly horizontal pipes half full of water, your going to have to experiment with methods of absorption, just remember not to choke your air flow beyond the 50% mark.

I would say that 3 kw your going to be working with at least 4 liters of primary fluid and 15 liters of secondary fluid for god sake you need an air flow fail safe switch on this monster or at least put in its own steel traffic light NEC cabinet or shed away from your house and lab.

personally I would just build the Pauling horn electrode design its cheaper, faster, simpler and more reliable but not quite as cool
IrC
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I think it is hard to beat a transformer from an oil furnace for long term reliability. On another note, did not have time to read all 11 pages to see if this patent has been mentioned. It seemed very interesting so I thought I should post it.

3081153 Automatic optimum air addition to nitric oxide absorption in nitric acid production

http://www.freepatentsonline.com/3081153.html

I include the link as it is often useful to study related patents.

Attachment: US3081153A.pdf (340kB)
This file has been downloaded 846 times

Skimming the thread I realize long ago neutrino asked me "why quartz", mentioning it's UV transparency. I never answered but it was merely a compromise since quartz would not melt so easily close to the arc. That was my reason, I knew UV would not be blocked but then again the chamber might survive longer with materials able to withstand high temperatures.

[Edited on 4-6-2013 by IrC]

"Science is the belief in the ignorance of the experts" Richard Feynman
hissingnoise
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 Quote: I think it is hard to beat a transformer from an oil furnace for long term reliability.

Not quite my experience, IrC ─ I lost one to overheating . . .
In a BE/Generator, the secondry is effectively shorted and a thermal cutout is essential for anyway long runs!

tinker Terry
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 Quote: Originally posted by axehandle I'm constructing one, and have made a web page which documents my progress and is continously updated. Comments, critizism, suggestions, questions etcetera are most welcome. http://species8472.dyndns.org/no2/no2.html

your website like doesn't work for me.

Curiosity may have killed the cat but it put mankind on the moon.
tinker Terry
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 Quote: Originally posted by axehandle Heh. Are yours more sophisticated than mine (e.g. using magnetic fields and DC arcs to form an oval arc)? In that case let's call it a draw. Seriously though, how's yours constructed? Edit: I think we could both benefit from a mutual exchange of design information to optimize our yields. The patent has expired long since.... This is my 6th reactor, all the previous ones have been made of glass and failed due to thermal stress; the 5th one actually employed watercooled hollow electrodes(which failed because of the conductivity of condensed water). This is the first one that actually seems to work, albeit I'll probably have to run it in 15 minute cycles for cooling reasons (15 minutes NST on, 15 minutes NST off, etc). Regards, /A [Edited on 2004-2-12 by axehandle]

Maybe use a none conductive coolant oil? alchol?

Curiosity may have killed the cat but it put mankind on the moon.
Xenoid
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 Quote: Originally posted by tinker Terry your website like doesn't work for me.

Probably because that post is nearly 10 years old -
Blue Matter
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Has anyone thought of using the magnets from a microwave magnetron to increase the size of the arc by creation a magnetic field. I think the magnets would be perfect if you put 2 on either side of a round container with the electrodes going threw the hole in the magnet. I am sure others have thought of more complex ways of creating the field but this seems like a simple solution. I am going to test this and get back to you on my results.

Pulverulescent
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 Quote: Has anyone thought of using the magnets from a microwave magnetron to increase the size of the arc by creation a magnetic field.

The travelling arc of a sealed-in Jacob's Ladder dissipates its heat (static arcs will cause overheating) throughout the reaction space ─ I used an old, tall glass sweet jar which became just hot to the touch on continuous working.

"I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones"

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Blue Matter
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Quote: Originally posted by Pulverulescent
 Quote: Has anyone thought of using the magnets from a microwave magnetron to increase the size of the arc by creation a magnetic field.

The travelling arc of a sealed-in Jacob's Ladder dissipates its heat (static arcs will cause overheating) throughout the reaction space ─ I used an old, tall glass sweet jar which became just hot to the touch on continuous working.

How is your reactor setup a cold water condenser or bubbling the gas through H202. What kind of concentration and production could I expect from a 12kv nst?

Marvin
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 Quote: Originally posted by Pulverulescent The travelling arc of a sealed-in Jacob's Ladder

The arc rises because the hot air rises. The arc is rising with the air rather than cutting through it.
scottjm
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I looked through this thread, and I have a few questions. I saw on Wikipedia that the reactor run by Birkeland they were able to get a yield of 15 MWh/Ton of nitric acid. That may seem like a lot, but that is only 7.5 kwh per pound. 7.5 kwh at US national average that is $0.90. Have any of you been able to get this kind of efficiency? What Kv would you recommend for this reaction? Some sources I read said as high as 31Kv, and some as low as 9Kv. Would a platinum catalyst help with the second reaction (2 NO + O 2 → 2 NO)? Blue Matter Hazard to Others Posts: 107 Registered: 20-6-2013 Location: US Member Is Offline Mood: Optimus  Quote: Originally posted by scottjm I looked through this thread, and I have a few questions. I saw on Wikipedia that the reactor run by Birkeland they were able to get a yield of 15 MWh/Ton of nitric acid. That may seem like a lot, but that is only 7.5 kwh per pound. 7.5 kwh at US national average that is$0.90. Have any of you been able to get this kind of efficiency? What Kv would you recommend for this reaction? Some sources I read said as high as 31Kv, and some as low as 9Kv. Would a platinum catalyst help with the second reaction (2 NO + O 2 → 2 NO)?

I think best is like 12kv 300ma

scottjm
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Quote: Originally posted by Blue Matter
 Quote: Originally posted by scottjm I looked through this thread, and I have a few questions. I saw on Wikipedia that the reactor run by Birkeland they were able to get a yield of 15 MWh/Ton of nitric acid. That may seem like a lot, but that is only 7.5 kwh per pound. 7.5 kwh at US national average that is \$0.90. Have any of you been able to get this kind of efficiency? What Kv would you recommend for this reaction? Some sources I read said as high as 31Kv, and some as low as 9Kv. Would a platinum catalyst help with the second reaction (2 NO + O 2 → 2 NO)?

I think best is like 12kv 300ma

Thank you. Anybody else have any ideas, or know about using a catalyst for the NO to NO2 process?
Pulverulescent
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NO is oxidised by O2 on contact ─ catalyst not required!

"I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones"

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I know I'm a bit on the late side ........but has anyone tried OZONE, this stuff will oxidize just about anything.

Put ur 15KV transformer to work on a ozone generator and feed it pure oxygen.

Genius creates many a great works............Labor alone finishes them!
Pulverulescent
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Ozone has been used to oxidise NO2 in the gas-phase!
A cold trap (dry ice) was used to collect pure N2O5 product.
The oxidation in DCM solution was found to be more efficient, though!

"I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones"

A Einstein
langevin
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Just some thoughts

Assuming an rotative tungsten electrode ( no need to drill or weld (hard to do) just clips or pinch it in the right angle). Speed must be determined.
Connection to the supply ( at this voltage) doesn't seems an issue
Assuming the other electrode could be the wall of the system. i e an outer cylinder (no need to be temperature resistant material due to the fact the sparks have low impact time (but repetitive).
Complete the system by two sealed sides ( may be glass) and flowing air through the apparatus. (could be two opposites holes in the outer cylinder).
Supply this system with an NST. 6 to 10 kV~
Sparks could be 1 inch long seeming an plasma ring.
Bubbling the exhaust gaz in water.
Concentrate the acid by distillation.

Note this trick (rotative electrode) is used in the Xray tubes ( at least for the high power ones) to reduce the temperature and increase the yield.

Does someone could comment theses thoughts?
Bert

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Now THAT... Looks a PROPER bit of the old school mad science!

How large does such an installation have to be for good efficiency?

I have long thought that a rural photovoltaic or wind generator installation would be better used to make fixed Nitrogen than to generate electricity for network distribution, especially in light of transmission losses, infrastructure build out costs and the interupted production due to low wind or lack of sunlight.

If the process were reasonably efficient and interruption during periods of low wind/night time didn't destroy the equipment...

[Edited on 19-8-2014 by Bert]

Rapopart’s Rules for critical commentary:

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Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).

Refinery
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B-E is good that it needs only compressed air and electricity, but it has serious drawback on energy consumption. Do you guys think that converting ammonia to NO with Ostwald is that difficult? Technically it only needs to change the electric arc into a catalyst. Ammonia is freely available as long as urea is, so I see a winner in here.
quantumcorespacealchemyst
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haber-bosh + birkeland eyde

langevin above mentions an interesting idea. i wonder about how that magnetic system in the video in the post by bert is set up also.

an idea i got from a forum poster on another thread,

using what jpsmith123 mentions (from thread linked below) about the arc being concentrated, the idea will involve

an air compressor into a quartz (very thick wall) vessel. this vessel is formed with pressure valves on the in and outlets and acts as the compression chamber (please tell me

where i may find find formulas for wall thickness pressure capacities of quartz and or borosilicate glass)

the gas/plasma is catalyzed by rhodium or rhodium/platinum which the electrodes are made of and/or powdered forms of those two metal/alloys as well (frit filters would be

needed i guess to keep them from exiting during purges)

while NO is oxidized by O2, the activations of pathways leading to NO may become lower, or it may do other unthought of stuff. the machine will probably need to be run in pulses

or with patterning run from a computer and is run with respect to pressure expansion, and has to take into account that/energy absorption. it will seemingly take good calculations

and tinkering. the catalyst when exited, also seems to add to the reactivity/pressure increase by further exiting the plasma. this gas when uncompressed

into water will seemingly cool it greatly and absorb well into it (perhaps to greatly, freezing it). the catalyst needs to be kept from depleting/contaminating the end product, although it may hopefully

be easily filtered. the electrodes themselves i guess are idealy the catalyst, arcing as jpsmith123 wrote. a plasmized catalyst may be interesting although it would mean

deteriorated electrodes and i that is why it is probably neccessary to run it in pulses. another possibilty but still probably idealy being run in pulses is to make the electrodes enter

the flask just at the edge of the microwave chamber so the liquid coolant may seep heat away from the electrodes fins which are on the outside of the shielding. the trouble here

may be that there is a waveguide effect that channels microwaves out of the faraday caging and along the electrodes. please tell me about the details of the radiation

behaviour here. i must mention that the electrodes will seemingly have to be tungsten with a thick coat of the catalyst so the uncoated part sticks [in/through]/[bonds to] the glass.

 Quote: Originally posted by jpsmith123 It seems that using microwaves to make nitric oxide may be the easiest and best way to go. At first I wondered if there would be a problem with impedance matching, but based on information I've found, it looks like it may work quite well. The following paper describes a plasma generator comprised of a 2.45 Ghz magnetron and a shorted waveguide with a triple stub tuner, that resulted in a reflected power of less than 1%; but even without the tuner, the reflected power was "typically less than 10%". That's good news. More good news is that with an airflow rate of 28 lpm, plasma flame temperatures of over 6000 degrees kelvin were achieved...that should make lots of nitric oxide. http://psfcwww2.psfc.mit.edu/library/01JA/01JA005/01JA005_ab... Finally, patent #6696662 describes a similar arrangement for creating a microwave plasma, only simpler in that it has neither a tuner nor the tapered waveguide section.

Quote: Originally posted by jpsmith123
Actually it may be the other way around.

In the patent and the paper I cited, the microwave discharge is confined to a shorted waveguide; thus the electric field would be significantly higer and consequently the electron energy and temperature would be higher as well, theoretically resulting in more NO.

I would think you would want to flow the air through this hot zone.

 Quote: Originally posted by Samosa My friend stopped by today and we got to run a few more tests on the microwave. The big conclusion of the day is that reasonable yields will only be obtained from large reaction vessels--the higher the volume, the better.

attached is the pdf. from the internet archived site pdf. link

Attachment: 01JA005_full.pdf (307kB)
This file has been downloaded 643 times

while a catalyst is said to not be neccesary, i think it wil be fun to find out what it does anyway. also i wonder if a tesla coil arcing perpendicularly across the microwave gap arc

with an electrode pair of rhodium or rhodium/platinum will make it even more fun to mess with? i dont know if that will work as the arcs may go to the lower voltage potential and

fry the system unless it is designed to do funny things like that. i want to build this, please give me some ideas

i just realized that pressure will effect the equilibrium of the gases which makes this more interesting.

according to http://en.wikipedia.org/wiki/Haber_process"

The most popular catalysts are based on iron promoted with K2O, CaO, SiO2, and Al2O3. The original Haber–Bosch reaction chambers used osmium as the catalyst. Haber

noted uranium was superior but harder to obtain."also "Some ammonia production utilizes ruthenium-based catalysts

(the KAAP process). Ruthenium forms more active catalysts that allows milder operating pressures."

essentially, this is combining haber-bosch and birkeland eyde

"Nitrogen (N2) is very unreactive because the molecules are held together by strong triple bonds. The Haber process relies on catalysts that accelerate the scission of this triple

bond."

[Edited on 18-11-2014 by quantumcorespacealchemyst]

[Edited on 18-11-2014 by quantumcorespacealchemyst]
WGTR
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I think you might be mixing the Ostwald process with the Birkeland-Eyde process.

I'm currently working on this myself. For the Birkeland reactor, 5000V and 40A were common specifications for the reactor. About 200kW went into the arc. There was an inductor in series with the reactor, to provide current limiting once the arc initiated. The electrodes were 8-10mm apart. The 5000V was needed to help ensure that the arc re-struck every cycle. Once the air ionized in the gap, the voltage would drop very low, as the current would be limited by the inductor. The flame would get blown out into a disc by an electromagnet, since the arc current was AC. The arc would get blown to one side of the reactor, then when the polarity reversed, it would shift to the other side, forming a disc. When blown out to the outer edges of the reactor, the voltage in the arc would rise closer to the full 5000V, since the path was over 1m long. These furnaces were adjusted to allow the arc to extinguish itself precisely once it reached the outer edge of the reactor.

The impedance in the inductor in the original furnaces was relatively low. In the above example it would be no more than 125 ohms. With a 5000V NST rated at 0.5A (short circuit current), that figure is 10,000 ohms. Although the voltage in the NST is the same as the high power designs, the arc is much cooler because of the lower arc current. Because of this cooler arc, the arc voltage is higher. At the same time, I don't think that power is getting transferred very efficiently to the arc in these designs, and a lot of ozone gets produced.

High voltage is needed to initially strike the arc. Failing that, the electrodes can be briefly touched together. I experimented with sharpened 1/16" thoriated tungsten electrodes to see what it would take to get an arc going. Anything over 2A at 50 DCV worked. I could draw an arc to about 0.5cm, with 30V DC across the electrodes. I was getting about 60W in the arc. The tungsten was rapidly consumed under these conditions. The appearance of radioactive smoke wisping away from them bothered me somewhat, so I decided to try 1/8" copper bus wire instead. The results were about the same, although the flame was "greener". The positive electrode got hot enough to melt, the negative one just oxidized.

The Birkeland-Eyde reactor used water-cooled copper electrodes that were said to last for 300 hours before needing service. The long life must be related to the cooling that they received. I have some copper capillary tubing that I'll try with water cooling, and see how that works.

Based on the figures used in industry, the voltage should be scaled to ≈250V open circuit when using a ≈2A current limit. A high voltage (1,000-5,000) supply can be placed in parallel with the low voltage supply to maintain arc stability. At least these figures are a starting point.

[Edited on 11-18-2014 by WGTR]
j_sum1

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I have heard it said that hafnium is very resistant to damage in sparking situations.
You might want to look at the list of materials that are used in spark plugs for inspiration.
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