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Posted: 9/3/2015 5:30:33 PM EDT
or smarter folks than I here......

Having a little silly conversation on a slow day with a few fellers. We got on the subject of things burning in a regular air atmosphere. It kind of struck me that maybe the materials that produce the most soot have the higher energy densities?

Am I on the right track here?
Link Posted: 9/3/2015 5:49:05 PM EDT
Soot  is from inefficient combustion.
Link Posted: 9/3/2015 5:52:35 PM EDT
[Last Edit: 9/3/2015 5:55:04 PM EDT by SuperJanitor]
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Originally Posted By fxntime:
Soot  is from inefficient combustion.
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True. But things like rubbing alcohol produce little to no soot in an open air atmosphere, whereas acetylene produces gobs.. I'm thinking its something to do with hydrocarbons and its probably something a 7th grade student could answer for me because I didn't pay enough attention in science class

Maybe Keith J will come along and fix me!
Link Posted: 9/3/2015 5:58:34 PM EDT
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Originally Posted By SuperJanitor:

True. But things like rubbing alcohol produce little to no soot in an open air atmosphere, whereas acetylene produces gobs.. I'm thinking its something to do with hydrocarbons and its probably something a 7th grade student could answer for me because I didn't pay enough attention in science class

Maybe Keith J will come along and fix me!
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Originally Posted By SuperJanitor:
Originally Posted By fxntime:
Soot  is from inefficient combustion.

True. But things like rubbing alcohol produce little to no soot in an open air atmosphere, whereas acetylene produces gobs.. I'm thinking its something to do with hydrocarbons and its probably something a 7th grade student could answer for me because I didn't pay enough attention in science class

Maybe Keith J will come along and fix me!


FPNI..

Acetylene produces soot due to too much fuel and not enough oxygen.  When you increase the oxy input to the combustion process, it produces less and less.  When it reaches the stoichiometric mixture it is the most efficient.
Link Posted: 9/3/2015 6:01:46 PM EDT
Stoichiometric mixture.
Link Posted: 9/3/2015 6:03:42 PM EDT
The higher the molecular weight  a hydrocarbon the more soot it will produce.  Soot comes from the chemistry in the fire turning hydrocarbons into high molecular weight polyaromatics.  The larger the building blocks the smaller the flame height and needed to produce soot because fewer steps are needed to produce it.



<---- Chemist who burns shit for a living.
Link Posted: 9/3/2015 6:06:54 PM EDT
[Last Edit: 9/3/2015 6:07:23 PM EDT by TescoVee]


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Originally Posted By Longboat:
FPNI..





Acetylene produces soot due to too much fuel and not enough oxygen.  When you increase the oxy input to the combustion process, it produces less and less.  When it reaches the stoichiometric mixture it is the most efficient.
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Originally Posted By Longboat:





Originally Posted By SuperJanitor:




Originally Posted By fxntime:


Soot  is from inefficient combustion.



True. But things like rubbing alcohol produce little to no soot in an open air atmosphere, whereas acetylene produces gobs.. I'm thinking its something to do with hydrocarbons and its probably something a 7th grade student could answer for me because I didn't pay enough attention in science class





Maybe Keith J will come along and fix me!






FPNI..





Acetylene produces soot due to too much fuel and not enough oxygen.  When you increase the oxy input to the combustion process, it produces less and less.  When it reaches the stoichiometric mixture it is the most efficient.
This is also true.  You need an oxygen poor environment to produce soot.  This is an isopropyl alcohol fire:

 















Even though the fire is poor in atmospheric oxygen and the flames are 15ft high almost no soot is produced because the molecule has a low molecular weight and a relatively high oxygen to carbon ratio.


 
Link Posted: 9/3/2015 6:13:22 PM EDT
Also, acetylene is an oddball.  It produces soot well even though it has a very low molecular weight.  It has a high energy density because it is triple bonded.  The polyaromatic hydrocarbons needed for soot are rings with a mix of conjugated double and single bonds (technically not true but for this it's good enough.)  Because of this it makes acetylene very efficient as a building block for the rings.
Link Posted: 9/3/2015 6:38:13 PM EDT
Thanks for the insightful replies. I always knew soot was produced on account of poor fuel/oxygen ratio. I was just wandering about the densities. That was a really intersting reply about the acetylene.
Link Posted: 9/3/2015 7:22:14 PM EDT
Just out of curiosity, are there any other energy dense but molecularly light fuels out there like acetylene?
Link Posted: 9/3/2015 8:27:21 PM EDT
Gases have low energy density, but generally burn faster. Sometimes its better to burn a less dense fuel faster than a high density fuel that burns slower. Think candle vs 87 octane vs methane.  
Link Posted: 9/3/2015 9:00:28 PM EDT
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Originally Posted By TescoVee:
This is also true.  You need an oxygen poor environment to produce soot.  This is an isopropyl alcohol fire:  

http://i1222.photobucket.com/albums/dd498/libalj/2015-09-02%2011.09.47_zpsovxj451s.jpg



Even though the fire is poor in atmospheric oxygen and the flames are 15ft high almost no soot is produced because the molecule has a low molecular weight and a relatively high oxygen to carbon ratio.
 
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Originally Posted By TescoVee:
Originally Posted By Longboat:
Originally Posted By SuperJanitor:
Originally Posted By fxntime:
Soot  is from inefficient combustion.

True. But things like rubbing alcohol produce little to no soot in an open air atmosphere, whereas acetylene produces gobs.. I'm thinking its something to do with hydrocarbons and its probably something a 7th grade student could answer for me because I didn't pay enough attention in science class

Maybe Keith J will come along and fix me!


FPNI..

Acetylene produces soot due to too much fuel and not enough oxygen.  When you increase the oxy input to the combustion process, it produces less and less.  When it reaches the stoichiometric mixture it is the most efficient.
This is also true.  You need an oxygen poor environment to produce soot.  This is an isopropyl alcohol fire:  

http://i1222.photobucket.com/albums/dd498/libalj/2015-09-02%2011.09.47_zpsovxj451s.jpg



Even though the fire is poor in atmospheric oxygen and the flames are 15ft high almost no soot is produced because the molecule has a low molecular weight and a relatively high oxygen to carbon ratio.
 



because isopropyl alcohol brings some of it's own Oxygen to the party...  

At first glance I would have thought you worked at the ATF Lab in Maryland but I see you list your location as WI....
Link Posted: 9/3/2015 9:41:17 PM EDT
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Originally Posted By Longboat:



because isopropyl alcohol brings some of it's own Oxygen to the party...  

At first glance I would have thought you worked at the ATF Lab in Maryland but I see you list your location as WI....
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Originally Posted By Longboat:
Originally Posted By TescoVee:
Originally Posted By Longboat:
Originally Posted By SuperJanitor:
Originally Posted By fxntime:
Soot  is from inefficient combustion.

True. But things like rubbing alcohol produce little to no soot in an open air atmosphere, whereas acetylene produces gobs.. I'm thinking its something to do with hydrocarbons and its probably something a 7th grade student could answer for me because I didn't pay enough attention in science class

Maybe Keith J will come along and fix me!


FPNI..

Acetylene produces soot due to too much fuel and not enough oxygen.  When you increase the oxy input to the combustion process, it produces less and less.  When it reaches the stoichiometric mixture it is the most efficient.
This is also true.  You need an oxygen poor environment to produce soot.  This is an isopropyl alcohol fire:  

http://i1222.photobucket.com/albums/dd498/libalj/2015-09-02%2011.09.47_zpsovxj451s.jpg



Even though the fire is poor in atmospheric oxygen and the flames are 15ft high almost no soot is produced because the molecule has a low molecular weight and a relatively high oxygen to carbon ratio.
 



because isopropyl alcohol brings some of it's own Oxygen to the party...  

At first glance I would have thought you worked at the ATF Lab in Maryland but I see you list your location as WI....

Didn't know that.
Link Posted: 9/3/2015 10:11:50 PM EDT
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Originally Posted By SuperJanitor:
Just out of curiosity, are there any other energy dense but molecularly light fuels out there like acetylene?
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Hydrogen + oxygen
Link Posted: 9/3/2015 10:24:38 PM EDT
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Originally Posted By Trollslayer:


Hydrogen + oxygen
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Originally Posted By Trollslayer:
Originally Posted By SuperJanitor:
Just out of curiosity, are there any other energy dense but molecularly light fuels out there like acetylene?


Hydrogen + oxygen

I didn't think hydrogen was that energy dense. I always thought the reason it made an attractive rocket propellent was because of of the ability to be stored in a liquid state. IOW, cram a lot of it in a little space. On the other hand, some rocket designs, including the first stage of the Saturn V used kerosene and LOX. Kerosene has a relatively high energy density.
Link Posted: 9/3/2015 10:31:42 PM EDT
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Originally Posted By SuperJanitor:

I didn't think hydrogen was that energy dense. I always thought the reason it made an attractive rocket propellent was because of of the ability to be stored in a liquid state. IOW, cram a lot of it in a little space. On the other hand, some rocket designs, including the first stage of the Saturn V used kerosene and LOX. Kerosene has a relatively high energy density.
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Originally Posted By SuperJanitor:
Originally Posted By Trollslayer:
Originally Posted By SuperJanitor:
Just out of curiosity, are there any other energy dense but molecularly light fuels out there like acetylene?


Hydrogen + oxygen

I didn't think hydrogen was that energy dense. I always thought the reason it made an attractive rocket propellent was because of of the ability to be stored in a liquid state. IOW, cram a lot of it in a little space. On the other hand, some rocket designs, including the first stage of the Saturn V used kerosene and LOX. Kerosene has a relatively high energy density.


What do you mean by density? Hydrogen is much higher on a  per/lb basis.

Link Posted: 9/3/2015 10:34:16 PM EDT

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Originally Posted By Longboat:







because isopropyl alcohol brings some of it's own Oxygen to the party...  



At first glance I would have thought you worked at the ATF Lab in Maryland but I see you list your location as WI....
View Quote
Nope, unlike the ATF my job involves preventing people and property from burning, not causing it.  

 
Link Posted: 9/3/2015 10:42:18 PM EDT
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Originally Posted By psychotr:


What do you mean by density? Hydrogen is much higher on a  per/lb basis.

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Originally Posted By psychotr:
Originally Posted By SuperJanitor:
Originally Posted By Trollslayer:
Originally Posted By SuperJanitor:
Just out of curiosity, are there any other energy dense but molecularly light fuels out there like acetylene?


Hydrogen + oxygen

I didn't think hydrogen was that energy dense. I always thought the reason it made an attractive rocket propellent was because of of the ability to be stored in a liquid state. IOW, cram a lot of it in a little space. On the other hand, some rocket designs, including the first stage of the Saturn V used kerosene and LOX. Kerosene has a relatively high energy density.


What do you mean by density? Hydrogen is much higher on a  per/lb basis.


By volume.
Link Posted: 9/3/2015 10:46:26 PM EDT
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Originally Posted By TescoVee:
Nope, unlike the ATF my job involves preventing people and property from burning, not causing it.  
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Originally Posted By TescoVee:
Originally Posted By Longboat:



because isopropyl alcohol brings some of it's own Oxygen to the party...  

At first glance I would have thought you worked at the ATF Lab in Maryland but I see you list your location as WI....
Nope, unlike the ATF my job involves preventing people and property from burning, not causing it.  

Nice!
Link Posted: 9/3/2015 10:56:44 PM EDT

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Originally Posted By SuperJanitor:





I didn't think hydrogen was that energy dense. I always thought the reason it made an attractive rocket propellent was because of of the ability to be stored in a liquid state. IOW, cram a lot of it in a little space. On the other hand, some rocket designs, including the first stage of the Saturn V used kerosene and LOX. Kerosene has a relatively high energy density.
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Originally Posted By SuperJanitor:



Originally Posted By Trollslayer:


Originally Posted By SuperJanitor:

Just out of curiosity, are there any other energy dense but molecularly light fuels out there like acetylene?




Hydrogen + oxygen


I didn't think hydrogen was that energy dense. I always thought the reason it made an attractive rocket propellent was because of of the ability to be stored in a liquid state. IOW, cram a lot of it in a little space. On the other hand, some rocket designs, including the first stage of the Saturn V used kerosene and LOX. Kerosene has a relatively high energy density.
I will add that a lot of properties of chemicals that make them high energy density (BTU/lb for the common folk) also make them produce soot.  These are not directly correlated so there are explosive exceptions like hydrogen which will ruin your day but produce no soot.  For soot it's all about the polyaromatic hydrocarbons.

 
Link Posted: 9/3/2015 11:03:28 PM EDT
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Originally Posted By TescoVee:
I will add that a lot of properties of chemicals that make them high energy density (BTU/lb for the common folk) also make them produce soot.  These are not directly correlated so there are explosive exceptions like hydrogen which will ruin your day but produce no soot.  For soot it's all about the polyaromatic hydrocarbons.  
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Originally Posted By TescoVee:
Originally Posted By SuperJanitor:
Originally Posted By Trollslayer:
Originally Posted By SuperJanitor:
Just out of curiosity, are there any other energy dense but molecularly light fuels out there like acetylene?


Hydrogen + oxygen

I didn't think hydrogen was that energy dense. I always thought the reason it made an attractive rocket propellent was because of of the ability to be stored in a liquid state. IOW, cram a lot of it in a little space. On the other hand, some rocket designs, including the first stage of the Saturn V used kerosene and LOX. Kerosene has a relatively high energy density.
I will add that a lot of properties of chemicals that make them high energy density (BTU/lb for the common folk) also make them produce soot.  These are not directly correlated so there are explosive exceptions like hydrogen which will ruin your day but produce no soot.  For soot it's all about the polyaromatic hydrocarbons.  



but rolling poly aromatic hydrocarbons doesn't sound as cool as rolling coal
Link Posted: 9/3/2015 11:05:34 PM EDT

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Originally Posted By midcap:
but rolling poly aromatic hydrocarbons doesn't sound as cool as rolling coal
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Originally Posted By midcap:



Originally Posted By TescoVee:


Originally Posted By SuperJanitor:


Originally Posted By Trollslayer:


Originally Posted By SuperJanitor:

Just out of curiosity, are there any other energy dense but molecularly light fuels out there like acetylene?




Hydrogen + oxygen


I didn't think hydrogen was that energy dense. I always thought the reason it made an attractive rocket propellent was because of of the ability to be stored in a liquid state. IOW, cram a lot of it in a little space. On the other hand, some rocket designs, including the first stage of the Saturn V used kerosene and LOX. Kerosene has a relatively high energy density.
I will add that a lot of properties of chemicals that make them high energy density (BTU/lb for the common folk) also make them produce soot.  These are not directly correlated so there are explosive exceptions like hydrogen which will ruin your day but produce no soot.  For soot it's all about the polyaromatic hydrocarbons.  






but rolling poly aromatic hydrocarbons doesn't sound as cool as rolling coal
It doesn't get you much pussy either.  

 
Link Posted: 9/3/2015 11:09:31 PM EDT
Neither does being married
Link Posted: 9/3/2015 11:16:13 PM EDT
This whole goofy half-lit train of thought got going today when we were bonding some grounds. We needed to bond some ground wire to ground rods. We use this crap they call cadweld. Basically, they give you a little crucible with a rubber bung in the bottom that you slip over your ground rod and then it has holes in the side to insert your wires. One its set up, you put in some thermite and light it off. It bonds all the metal together damn near instantly. Then the rubber bung on the bottom catches fire and burns.

At any rate, the soot is really intense for the little piece of rubber burning. Funny how something silly like this will get goofy speculations and theories going
Link Posted: 9/3/2015 11:16:52 PM EDT
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Originally Posted By TescoVee:
It doesn't get you much pussy either.    
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Originally Posted By TescoVee:
Originally Posted By midcap:
[quot]Originally Posted By TescoVee:
Originally Posted By SuperJanitor:
Originally Posted By Trollslayer:
Originally Posted By SuperJanitor:
Just out of curiosity, are there any other energy dense but molecularly light fuels out there like acetylene?


Hydrogen + oxygen[/qute]
I didn't think hydrogen was that energy dense. I always thought the reason it made an attractive rocket propellent was because of of the ability to be stored in a liquid state. IOW, cram a lot of it in a little space. On the other hand, some rocket designs, including the first stage of the Saturn V used kerosene and LOX. Kerosene has a relatively high energy density.
I will add that a lot of properties of chemicals that make them high energy density (BTU/lb for the common folk) also make them produce soot.  These are not directly correlated so there are explosive exceptions like hydrogen which will ruin your day but produce no soot.  For soot it's all about the polyaromatic hydrocarbons.  



but rolling poly aromatic hydrocarbons doesn't sound as cool as rolling coal
It doesn't get you much pussy either.    


Link Posted: 9/3/2015 11:21:48 PM EDT
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Originally Posted By SuperJanitor:
This whole goofy half-lit train of thought got going today when we were bonding some grounds. We needed to bond some ground wire to ground rods. We use this crap they call cadweld. Basically, they give you a little crucible with a rubber bung in the bottom that you slip over your ground rod and then it has holes in the side to insert your wires. One its set up, you put in some thermite and light it off. It bonds all the metal together damn near instantly. Then the rubber bung on the bottom catches fire and burns.

At any rate, the soot is really intense for the little piece of rubber burning. Funny how something silly like this will get goofy speculations and theories going
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I take it you've never burned tires.
Link Posted: 9/3/2015 11:23:47 PM EDT
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Originally Posted By JVD:


I take it you've never burned tires.
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Originally Posted By JVD:
Originally Posted By SuperJanitor:
This whole goofy half-lit train of thought got going today when we were bonding some grounds. We needed to bond some ground wire to ground rods. We use this crap they call cadweld. Basically, they give you a little crucible with a rubber bung in the bottom that you slip over your ground rod and then it has holes in the side to insert your wires. One its set up, you put in some thermite and light it off. It bonds all the metal together damn near instantly. Then the rubber bung on the bottom catches fire and burns.

At any rate, the soot is really intense for the little piece of rubber burning. Funny how something silly like this will get goofy speculations and theories going


I take it you've never burned tires.

Shhhh!

Not for years!
Link Posted: 9/4/2015 8:22:43 PM EDT
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Originally Posted By TescoVee:
I will add that a lot of properties of chemicals that make them high energy density (BTU/lb for the common folk) also make them produce soot.  These are not directly correlated so there are explosive exceptions like hydrogen which will ruin your day but produce no soot.  For soot it's all about the polyaromatic hydrocarbons.  
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Originally Posted By TescoVee:
Originally Posted By SuperJanitor:
Originally Posted By Trollslayer:
Originally Posted By SuperJanitor:
Just out of curiosity, are there any other energy dense but molecularly light fuels out there like acetylene?


Hydrogen + oxygen

I didn't think hydrogen was that energy dense. I always thought the reason it made an attractive rocket propellent was because of of the ability to be stored in a liquid state. IOW, cram a lot of it in a little space. On the other hand, some rocket designs, including the first stage of the Saturn V used kerosene and LOX. Kerosene has a relatively high energy density.
I will add that a lot of properties of chemicals that make them high energy density (BTU/lb for the common folk) also make them produce soot.  These are not directly correlated so there are explosive exceptions like hydrogen which will ruin your day but produce no soot.  For soot it's all about the polyaromatic hydrocarbons.  

BTW, thank you! That was really kind of the answer I was searching for
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