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Author: Subject: Druken Aga Challenge (DAC) #3 - Closed (but open to discussion)
deltaH
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[*] posted on 28-2-2015 at 21:59


I think he's problem is less sustaining combustion than starting combustion. With a heat of combustion of 19MJ/kg, soybeans MUST be combustible, however, I suspect the initial pyrolysis the bean undergoes is mildly endothermic and I think this is where j_sum is getting undone at the moment.



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[*] posted on 1-3-2015 at 06:05


How about a small furnace... A pipe set thru a bed of charcoal, and fed hot air thru the bottom via the heat gun idea.

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Etaoin Shrdlu
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[*] posted on 1-3-2015 at 06:17


Quote: Originally posted by j_sum1  
Quote: Originally posted by Etaoin Shrdlu  
Soybeans are known to undergo spontaneous combustion in storage. I'm very surprised yours won't burn even impregnated with an oxidizer.

Most spontaneous combustion scenarios are a result of moisture, the action of bacteria, a resultant increase in temperature and the presence of volatiles. I think I have effectively eliminated all four of these.

Moisture and bacteria only produce the heat necessary to start the reaction. They don't actually aid the combustion themselves that I know of, moisture at least should hinder it. The increase in temperature of course you're providing yourself trying to start the fire. I wasn't aware volatiles were necessary.

DeltaH is probably correct unless you have weird soybeans.

EDIT: Hmm, bought a butane candle-lighter and a pound of soybeans to see for myself. A pile of five of them just charred. About 30 of them the flame spread into pockets and started (apparently) separate fires that burned out within a few seconds when I took the heat away. Confining them more closely with a loose spring of wire had more or less the same effect. Either the lighter's not covering enough area, or it's not hot enough to start anything self-sustaining. I'm going to try to mill some of them and see if increasing the surface area helps.

[Edited on 3-1-2015 by Etaoin Shrdlu]
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[*] posted on 1-3-2015 at 15:01


Quote: Originally posted by Etaoin Shrdlu  

Moisture and bacteria only produce the heat necessary to start the reaction. They don't actually aid the combustion themselves that I know of, moisture at least should hinder it. The increase in temperature of course you're providing yourself trying to start the fire. I wasn't aware volatiles were necessary.

DeltaH is probably correct unless you have weird soybeans.

EDIT: Hmm, bought a butane candle-lighter and a pound of soybeans to see for myself. A pile of five of them just charred. About 30 of them the flame spread into pockets and started (apparently) separate fires that burned out within a few seconds when I took the heat away. Confining them more closely with a loose spring of wire had more or less the same effect. Either the lighter's not covering enough area, or it's not hot enough to start anything self-sustaining. I'm going to try to mill some of them and see if increasing the surface area helps.

[Edited on 3-1-2015 by Etaoin Shrdlu]

Yaaay!! I have an accomplice. (As well as numerous consultants.)
What you describe ES is exactly what I observed: both for untreated beans and also for the soaked and dried.

Lighting up a charcoal fire seems like an ok idea but my thought is unless it gets very hot, a handful of beans will smother it easily. And between the charcoal and beans, the overall protein content is likely to dip below 25% This means that peanuts will be my next attempt.
I agree that soy beans should work but finding the exact conditions to get them to ignite is going to take some experimenting.

@deltaH
I read ideashack last night. I understand your interest in this thread. Some really great ideas floated. To my thinking, the plaster is only a small step from marketable. But it would depend on economics of production as well. Anyway, that's for another conversation. I might PM some thoughts as they develop.
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[*] posted on 1-3-2015 at 15:48


why are dried beans not igniting ?

Too little Heat, Mass, Surface Area or Oxygen ?

It's Organic : remove the water and It WILL burn.




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[*] posted on 1-3-2015 at 16:10


Well, hitting it with a propane torch should be enough to get it to temperature. But the torch itself probably steals all available oxygen.
Blowing on the fire only served to snuff the flames more quickly. I couldn't get much of a glow out of the beans themselves.
Getting oxygen to pass through the bean pile is probably not the limiting factor at this stage. It might be an issue with some fire configurations but I expect that once the pyre is going, it will suck O2 through without bellows or forcing air.

I think it is mostly a situation of heat dissipation. A high temperature is required and in the initial stages of a fire, especially a small one, the heat dissipates into the environment quickly and the temperature drops. I might play with passing some pure O2 onto the glowing beans to aid the kinetics a bit and get the temp up. But again, that will have to wait until another weekend. Peanuts first. I want to test the collection next.
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[*] posted on 1-3-2015 at 17:04


I'm fairly sure the reason the beans aren't burning is the same reason that coal doesn't burn when you hit it with a blowtorch - the activation energy is to high. Therefore I would suggest starting the soybeans burning the same way I start my forge: by having a bed of easily burnable wood ships or similar underneath the soybeans, then blowing air through the wood past the soybeans.
If you have trouble igniting the wood underneath all those beans, I suggest a judicial application of hydrocarbons.
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[*] posted on 4-3-2015 at 19:21


Coarse ground flour charred more quickly but still wouldn't light off the candle lighter. Mixing a small part of it with an approximately equal volume of potassium permanganate started a nice hot fire when lit. Ignited in a few seconds and the rest of the flour burned close to the edges of the pile before stopping. I only tried with a couple tablespoons; I suspect it may work better on a larger scale but it's too dark and cold out to set anything up now.
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[*] posted on 4-3-2015 at 19:29


Quote: Originally posted by Etaoin Shrdlu  
Coarse ground flour charred more quickly but still wouldn't light off the candle lighter. Mixing a small part of it with an approximately equal volume of potassium permanganate started a nice hot fire when lit. Ignited in a few seconds and the rest of the flour burned close to the edges of the pile before stopping. I only tried with a couple tablespoons; I suspect it may work better on a larger scale but it's too dark and cold out to set anything up now.
\


Didn't you look up three posts...


Make a simple pipe furnace that pre heats the beans.

They will be almost charcoal by the time a heat gun is used for oxygen.

too much over thinking...




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[*] posted on 4-3-2015 at 19:37


The fun I get out of this is by not using another fuel. :D

Others can do as they like.
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[*] posted on 4-3-2015 at 19:42


Dude, I'm talking about your fuel.

Run a pipe thru a bead of coals, and pre carbonize the fuel.

Is that science enough?

Collect the vapor at the head of that pipe.




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[*] posted on 4-3-2015 at 19:43


Coal is another fuel.

EDIT: Dear lord. I'm not trying to complete the challenge, I'm trying to burn soybeans.

[Edited on 3-5-2015 by Etaoin Shrdlu]
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[*] posted on 4-3-2015 at 20:12


What I mean is a pipe full of soy beans run up thru a bed of coal. The pipe is whatever the temp of the coal bed is regulated at, and the beans are fed hot air from the bottom.

The vapors from the beans are separated from the coal bed via the pipe.




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[*] posted on 5-3-2015 at 10:46


Yes. That's still using coal. I do not want to use another fuel than soybeans. I already know adding heat from another source will help, no need to test it.
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[*] posted on 5-3-2015 at 12:26


A wild thought : powder the beans and blow the dust into some sort of starter flame.

The Air blowing the dust should help with the combustion, although it will be a fine line between blowing Enough to carry the bean dust and blowing it Out.

Perhaps blowing vertically Upwards through a cylinder containing an amount of bean dust would create an area in the cylinder where combustion is favourable.

[Edited on 5-3-2015 by aga]




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[*] posted on 5-3-2015 at 14:24


Quote: Originally posted by aga  
A wild thought : powder the beans and blow the dust into some sort of starter flame.

The Air blowing the dust should help with the combustion, although it will be a fine line between blowing Enough to carry the bean dust and blowing it Out.

Perhaps blowing vertically Upwards through a cylinder containing an amount of bean dust would create an area in the cylinder where combustion is favourable.

[Edited on 5-3-2015 by aga]



There is also a risk of an explosion or an uncontrolled combustion.

I've seen what happens when you mix a flammable dust (epoxy resin / carbon fiber) with a propane turbo heater.

A kid sweeping the shop pushed a broom full of dust behind the intake, and the short blast blew the deflector cone out of the heater.




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[*] posted on 5-3-2015 at 14:33


Grain Silo explosions were what gave me the idea.



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[*] posted on 5-3-2015 at 14:38


You're BAD!!!

Time out Mister. :(




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[*] posted on 5-3-2015 at 14:42


Huh ? Sounds workable to me.

Bean dust & Air, set fire to it.




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[*] posted on 5-3-2015 at 14:53


How about de-constructing a Microwave oven, and using the magnatron?



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[*] posted on 5-3-2015 at 15:01


For what purpose, exactly ?



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[*] posted on 5-3-2015 at 16:56


Perhaps you could mix the powdered beans with a metallic compound, and convert the magnatron into a furnace...

https://www.youtube.com/watch?v=ft8of6ZeFNM





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[*] posted on 5-3-2015 at 21:46


This is much of a muchness. Just pyrolyse the beans in a tin on the coals of a barbie and be done with it. Simple, no mess, no fuss. Don't forget to punch a small hole in the top of the tin for the volatiles to escape. You can then impregnate the charred beans with catalyst to your heart's content without anything going awry.

Need to scale up? No problem, use a 25l paint drum, build a fire around it, make lots of 'charoya' :)

[Edited on 6-3-2015 by deltaH]




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deltaH
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[*] posted on 5-3-2015 at 21:51


Yay, that was my 1000th post!

I am now an 'extremely dangerous source of unreferenced speculation' :D

[Edited on 6-3-2015 by deltaH]




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[*] posted on 5-3-2015 at 21:55


Quote: Originally posted by deltaH  
Yay, that was my 1000th post!

I am now an 'extremely dangerous source of unreferenced speculation' :D

[Edited on 6-3-2015 by deltaH]


Sweet! Congratulations!




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