256 replies to this topic

[MDH]

Hmm. I wonder if there is something we could do to further decompose all of those extra solids within BP's burning time.

BP definitely is a curious substance.

[Mumbles]

Davis spells it with an F, because he is american. Sulfur is the accepted spelling by the IUPAC, and even the Royal Society of Chemistry(UK based). I think it's about time you guys shaped up.

It all depends on how davis analysed the BP. It can more or less be assumed that it was first washed with water to remove the KNO3. This is the critical part of this. The sulfur is removed with carbon disulfide. The charcoal left over is assumed to be pure, and is burned to completion. Anything left over is "ash". This will remove some of the ash based upon decomposing the carbonates and other salts in the wood.

I'd have to read through Davis again, but depending on the proceedure used, will give different results. If the BP was actually analyzed by solvent, all the solubles from the charcoal would be extracted with the potassium nitrate, and account for the lower than normal percentage of charcoal(based upon 75-15-10) after accounting for the moisture. If accepting a pure 75-15-10 mixture, and doing a bit of math you arrive at around 6.5% ash.

The one I posted gives an analysis of all inorganic salts, not just that which is left over after burning. Probably all soluble organics as well such as simple sugars. The one davis posts is just that which is left over after complete combustion. The analysis I posted might be better categorized as non-charcoal proportion. Heating to completely decompose would remove all these sugars, and modify the composition of the ash.

To truely analyze charcoal, you have to do it before mixing it with anything, as it will modify it. I think inorganic proportion is a better measure of it's quality. You will notice excessive bubbling if you mix commercial charcoal with acid. It could be possible to measure the gas produced.

[Pyrogeorge]

This is a method is how i make my charcoal..this tin is filled with newspaper to test it.
Also i set fire at the top because the smoke smells horrible

[BrightStar]

Has anyone tried charcoaling ordinary sawn spruce from the builders merchants?

I'm curious as to how this would compare with lumpwood barbeque charcoal or garden chips in charcoal stars and fountains etc. I've found the garden stuff a bit variable recently...

Edited by BrightStar, 27 April 2008 - 06:02 PM.

[Sambo]

For my pine charcoal i use CLS timber from B&Q, is about £1.50 - £2 for 2.5m, i just chop it up on a mitre saw and split it. It seems to split very easily too - much easier than the uasual 2 by 4. I find the charcoal perfect for bp in fountains and rockets and crys star comps.

[W.P]

This article has a comprehensive list of different charcoal BPs and approximated burn rates, it should answer your question.

EDIT: Sorry, I didn't notice the last post was a month ago.

Edited by W.P, 24 May 2008 - 10:33 PM.

[cooperman435]

White pine is indeed a very good charcoal for bp. My first true fast bp was made from just 2x3 timber (untreated with anything) charcoaled on a fire in a roses chocolate tin.

Im mself a little confused why a charcoal can be so fast when its also used as a long duration spark producer which I assumed before deemed it slower burning type of charcoal but hey this is an art not science.

[pyromaniac303]

I think pine lends its self to long duration/distance sparks due to its density, as it is less affected by air resistance when ejected from a fountain nozze. It also hold together well, unlike willow or balsa which are easily reduced to dust between the fingers, so does not break up so much in the air when it is ejected. It is not as simple as just the burn rate affecting spark production, can get fairly complicated with charcoal sparks that seem to split/branch (read about senko hanabi effects for more info on this)

[cooperman435]

But by that reasoning the denser the charcoal the better for long duration spark production? That would mean hardwood charcoal was better still?

[seymour]

Careful there... Hardwood does not mean that the wood is dense, or even hard. While ON AVERAGE hardwoods (broad leafed, usually sugar based sap) are denser than softwoods (conifers, usually resin based sap) the range of density in both catagories covers pretty much anything, from the extremely dense (and useless for pyro) softwood Yew, to the hardwoods we love for BP, Willow, Balsa ect...


Am I being pedantic?

[digger]

Well I until now I have had no need to make any charcoal however I now have a need for a few different types of charcoal for a bit of experimentation.

I tried the drum within a drum method today (20gal inside a 50gal). The whole process took about three hours from lighting it to having finished charcoal.

For this first run I used pine. I started with about 20kg and finished with a little over 4kg of good quality charcoal with no evidence of ash or unpyrolised wood.

So here are a few pics for you to have a look at.

Ready to load the first drum into the second


Ready to light the fire


Just starting to get going now


Really getting going now


Very nearly finished now


completed charcoal ready to be powdered

[pyrotrev]

Knowing that you're a very scientific gent Gareth, did you make any temperature measurements inside the can?

[digger]

Knowing that you're a very scientific gent Gareth, did you make any temperature measurements inside the can?

I did consider it, but I only decided that I was going to make some charcoal on Friday so I just chucked it all together with stuff I had lying around and it seemed to turn out OK. Maybe next time I will throw in a thermocouple (I know I have one knocking around somewhere).

What do you suggest I should be looking for?

[digger]

Well I have spent the evening turning the charcoal into powder in my mill (12 liter jar). I have to say when I do this again I think I am going to need a much larger mill jar like maybe 60 liter.

So the final yield is 20%. I got a tad over 4kg of powder from 20kg of wood. I may have got another 500g if it had not floated away in the wind when I was sieving it.

What a messy job I looked like a coal miner when I had finished.

[pyrotrev]

I did consider it, but I only decided that I was going to make some charcoal on Friday so I just chucked it all together with stuff I had lying around and it seemed to turn out OK. Maybe next time I will throw in a thermocouple (I know I have one knocking around somewhere).

What do you suggest I should be looking for?

I read somewhere that the best charcoal was made with pyrolysis at <500deg C - it would be interesting to know what sort of temperatures the 2 can method achieves as the product certainly looks good.