Heating Torch Using a Fuel That Does Not Contain Carbon

[mybrotherdarre]

I am looking for a fuel for a torch to heat an experiment to 500-1200C. We do not want to introduce exterior sources of Carbon. H2 cannot be used as a fuel because excess H2 will also throw off the results. My professor suggested SiH4, but I cannot find any information on silane as a torch fuel. Anybody have any ideas?

 

[mfb]

Something nitrogen-based? Ammonia (+catalyst), maybe even with nitrogen dioxide to provide oxygen?
No idea if the temperature is sufficient. And it is toxic.

Are other heating methods (without combustion) an option?

 

[mybrotherdarre]

We aren't using Nitrogen anymore for the carrier gas because it messes with the GC, I guess, so I don't know if the ammonia will affect things too much or not - but I'll bring it up. Thank you for the suggestion!

I am trying to find alternate heating methods to present as well as an optional torch fuel. The alternate heating methods seem to be easier to find, and I am having a ton of trouble finding fuels that fit the bill. Does anyone know anything about burning SiH4? Does it create a lot of SiO2? Will the buildup be a problem for the equipment and sensors?

 

[SteamKing]

Well, if you can't use H2 because of the potential for hydrogen contamination of your experiment, then perhaps SiH4 or ammonia isn't the way to go either, since both contain hydrogen.

Why does your heating source have to be a torch anyway? If you are worried about contamination, it seems like some sort of electrical heater or furnace would be the way to go.

If you don't want to introduce carbon contamination, have you sealed your experiment? After all, air has CO2 in it.

 

[Q_Goest]

I like SteamKing's idea. Instead of actually burning a fuel and using the combustion products, could you use a very hot gas such as air, nitrogen or argon and propel it under pressure? Another option might be superheated steam. You would heat the gas or steam to the temperature you want under pressure and use a valve and nozzle to direct the gas where you want it. Heat could come from any energy source such as an electric or hydrocarbon fuel source.

 

[etudiant]

Is superheated steam or nitrogen even chemically stable at 1200C ?
The hot gas concept seems very promising otherwise, but it would probably be best to use an inert gas such as Argon or Neon.

 

[mfb]

Nitrogen is fine, and cheaper than argon or neon.
If hot oxygen is not an issue, you can even use air.

 

[Borek]

That's not exactly what you are asking for, but there are several known gas mixtures that give a high flame temperature used for AAS, see an example list here.

Perhaps the list will give you some new ideas.

 

[SteamKing]

The OP was concerned about possible contamination of his experiment by carbon and hydrogen. Most of the fuels on the AAS list are composed of carbon or hydrogen, or both. IMO, a non-combustible source of heat would eliminate contamination of the experiment.

 

[Borek]

Sure. But knowing where such mixtures are used means another keywords to look for, doesn't it?

 

[bikengr]

that reminds me...

I recall learning, years ago, about a welding process called "atomic hydrogen". I think the idea was, send H2 through an arc, which heated it up and in the process dissociated it. Not only was it hot, but also had a large 'latent heat' of recombination, producing very high temperatures. I wuz wundering -- could N2 be dissociated the same way?

http://en.wikipedia.org/wiki/Atomic_hydrogen_welding

 

[Baluncore]

Consider using a hollow ellipsoidal reflector with a halogen globe at one focus and the item to be heated at the other. Non-contact and adjustable to over 3000K.

 

[rollingstein]

Try the book "Ignition" by John Clark.

Lot's of non C non H propellents there I recall. But they are nasty, toxic, unstable beasts.

Chemistries based on N / F / Cl / B / Si abound...

 

[Windadct]

What is the material - does it have to be a torch? OR as suggested a superheated inert gas -