Naked Science Forum
General Science => General Science => Topic started by: eric2011 on 30/04/2022 15:03:25
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Hi. Hope you guys are ok. I need an assistance to anybody who has done this. If I make a charcoal foundry and put two hairdryers one on each side to blow air do you think the temperature of the heat the furnace produces reach at least 1700 C?
Thanks
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Unlikely. Charcoal isn't expected to exceed 1500.
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If I make a charcoal foundry and put two hairdryers one on each side to blow air do you think the temperature of the heat the furnace produces reach at least 1700 C
I don't think hair dryers heat the air hot enough to melt steel, unless it is Binford 900 or something.
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Try a hot air gun paint stripper! The key to achieving high temperatures is mass, you will need a large volume to keep a large temperature. Insulation will not work as you have a problem with the fire needing oxygen.
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People have- albeit with difficulty- melting cast iron with air and charcoal furnaces for thousands of years- and without the advantage of a powered air blower.
It should still be possible in the 21st C.
But getting to 1700C is going to be tricky.
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Thanks fellas!
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By the way, How much maximum temperature an ordinary homemade charcoal foundry can get? with a single hairdryer. Does anybody ever measured the temperature when charcoal heat is at maximum temperature?
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The theoretical limit is about 2200C
https://en.wikipedia.org/wiki/Adiabatic_flame_temperature
what you actually get will depend on the design.
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By the way, How much maximum temperature an ordinary homemade charcoal foundry can get? with a single hairdryer. Does anybody ever measured the temperature when charcoal heat is at maximum temperature?
Theoretically it is energy released is an addition, the energy required to raise the mass of the temperature of the fuel and oxidiser is removed leaving a net addition to the mass you wish to heat. But there are a multitude of factors such as thermal resistance, convection radiation etc.
You could try running it on neat oxygen gas or fluorine if you can find it. But if you pump in hot air via a heat gun at 600 degrees I imagine the air will be hot enough to be above the flash temperature of charcoal. Essentially your fire should be smokeless and shall not suffer from surface temperature lag needing to heat the fuel surface, any vapour from the fuel will ignite and the fuel itself will be completely self heating to flash temperature.
I am not familiar with charcoals flash temperature but it is probably around the 400- 600 mark.
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I am not familiar with charcoals flash temperature
It doesn't have one.
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I am not familiar with charcoals flash temperature
It doesn't have one.
I just googled it.
The flashpoint of charcoal is the temperature at which it will ignite and give off an open flame. The Flashpoint of Charcoal is 40 degrees Celsius. Dec 23, 2021
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I am not familiar with charcoals flash temperature
It doesn't have one.
I just googled it.
The flashpoint of charcoal is the temperature at which it will ignite and give off an open flame. The Flashpoint of Charcoal is 40 degrees Celsius. Dec 23, 2021
And today you learned that Google doesn't always get things right.
Do you really believe that you can't light charcoal in cold weather, or that you can light a barbecue with a match- as long as the weather is warm?
"In chemistry, the flash point of a volatile material is the lowest temperature at which its vapors ignite if given an ignition source.[1]"
From
https://en.wikipedia.org/wiki/Flash_point
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And today you learned that Google doesn't always get things right.
I know. My experiments on diffraction of light tought me a thing or two, among others. Although a statement from an anonymous dude in the internet is usually even less reliable, especially when no evidence is given.
What do you mean by saying that charcoals don't have flash point?
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especially when no evidence is given.
Just as well I gave you evidence then, isn't it.
What do you mean by saying that charcoals don't have flash point?
Well, which bit(s) of these don't you understand?
Do you really believe that you can't light charcoal in cold weather, or that you can light a barbecue with a match- as long as the weather is warm?
"In chemistry, the flash point of a volatile material is the lowest temperature at which its vapors ignite if given an ignition source.[1]"
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especially when no evidence is given.
Just as well I gave you evidence then, isn't it.
What do you mean by saying that charcoals don't have flash point?
Well, which bit(s) of these don't you understand?
Do you really believe that you can't light charcoal in cold weather, or that you can light a barbecue with a match- as long as the weather is warm?
"In chemistry, the flash point of a volatile material is the lowest temperature at which its vapors ignite if given an ignition source.[1]"
I'll believe you if you show a video showing about it which I can replicate myself. I'll accept some other forms of evidence if I can confirm their validity.
Well, which bit(s) of these don't you understand?
The flashpoint of charcoal is the temperature at which it will ignite and give off an open flame. The Flashpoint of Charcoal is 40 degrees Celsius. Dec 23, 2021
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I'll believe you if you show a video showing about it which I can replicate myself. I'll accept some other forms of evidence if I can confirm their validity.
You want a video of me using a match and failing to set fire to charcoal that has been warmed to over 40C?
Really?
Why?
Wouldn't it be better if you just stopped and thought about it?
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Well, which bit(s) of these don't you understand?
The only bit I don't understand is why you posted it- because it's clearly wrong.
Did you send the author a request for a video demonstrating the claim's truth?
Or do you only ask me?
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I'll believe you if you show a video showing about it which I can replicate myself. I'll accept some other forms of evidence if I can confirm their validity.
You want a video of me using a match and failing to set fire to charcoal that has been warmed to over 40C?
Really?
Why?
Wouldn't it be better if you just stopped and thought about it?
It doesn't have to be you. It can be anyone. Don't take it personal.
The evidence should show the limiting factors. e. g. failing to set charcoal to burn below 40C but success when it's over 40C. Some other influential parameters should be stated, such as particle size of the charcoal, air pressure, oxygen concentration, humidity, spark size/energy.
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I'll believe you if you show a video showing about it which I can replicate myself. I'll accept some other forms of evidence if I can confirm their validity.
You want a video of me using a match and failing to set fire to charcoal that has been warmed to over 40C?
Really?
Why?
Wouldn't it be better if you just stopped and thought about it?
It doesn't have to be you. It can be anyone. Don't take it personal.
The evidence should show the limiting factors. e. g. failing to set charcoal to burn below 40C but success when it's over 40C. Some other influential parameters should be stated, such as particle size of the charcoal, air pressure, oxygen concentration, humidity, spark size/energy.
You are probably the only person on Earth who thinks that a match near a block of warm charcoal will set it on fire.
So you should do the experiment.
The rest of us already know the answer.
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Did you send the author a request for a video demonstrating the claim's truth?
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You are probably the only person on Earth who thinks that a match near a block of warm charcoal will set it on fire.
So you should do the experiment.
The rest of us already know the answer.
So you think you can read my mind.
It would be easier if it's in the form of powder.
The author of the article shown in google search thinks that flash point of charcoal is 40 degree C. How would you reconcile that with your statement above?
If I have the time and other resources to do the experiment, I'll do it. But currently I'm occupied with something else that I think are more important and urgent.
What makes you think that you can represent the rest of us?
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What do you mean by saying that charcoals don't have flash point?
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Did you send the author a request for a video demonstrating the claim's truth?
I haven't. Do I have to?
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The author of the article shown in google search thinks that flash point of charcoal is 40 degree C. How would you reconcile that with your statement above?
By pointing out that he is wrong.
Why don't you understand that?
If he was right then putting a match near a piece of charcoal on a warm day would set the stuff on fire.
Do you understand what "flash point" means?
I haven't. Do I have to?
You asked me; why not him?
Why are you still asking me about something which someone else wrote, and which is clearly wrong?
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What do you mean by saying that charcoals don't have flash point?
Charcoal doesn't have a defined flash point.
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I am not familiar with charcoals flash temperature
It doesn't have one.
I just googled it.
The flashpoint of charcoal is the temperature at which it will ignite and give off an open flame. The Flashpoint of Charcoal is 40 degrees Celsius. Dec 23, 2021
40c seems a bit low, at that temperature in hot countries you would not be able to smoke on a hot day. Wood and charcoal go through a couple of different stages of cumbustion. First they are heated causing the release of smoke from the wood as the cellulose decomposes, secondly the remainder oxidises. If the flash temperature of the vapour only needed to be 40c fires would not smoke I would not think.
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By pointing out that he is wrong.
Which means I'm not the only one, contrary to your claim.
https://fireproofdepot.com/is-charcoal-flammable/
What Is The Flashpoint Of Charcoal?
The flashpoint of charcoal is the temperature at which it will ignite and give off an open flame. The Flashpoint of Charcoal is 40 degrees Celsius.
This is the temperature that should be reached to make a piece of charcoal useful for cooking or burning other substances.
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Charcoal doesn't have a defined flash point.
Does it mean that it can't be ignited even in elevated temperature?
Does sugar have a flash point?
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You asked me; why not him?
Why are you still asking me about something which someone else wrote, and which is clearly wrong?
This video uses coal dust instead of charcoal dust, but I think it can represent my point.
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Which means I'm not the only one, contrary to your claim.
You would need to ask him if it's a mistake or something.
You, on the other hand, seem to genuinely believe it.
Feel free to ask him.
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Does it mean that it can't be ignited even in elevated temperature?
No that would be an unbelievably stupid thing to say, since it is used as a fuel.
Does sugar have a flash point?
Do the experiment , and find out.
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but I think it can represent my point.
What point?
He certainly didn't do a series of experiments at different temperatures and show that there was a change in behaviour at 40C.
You really don't understand what a flash point is, do you?
Why not just google it?
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What point?
It doesn't have to be you. It can be anyone. Don't take it personal.
The evidence should show the limiting factors. e. g. failing to set charcoal to burn below 40C but success when it's over 40C. Some other influential parameters should be stated, such as particle size of the charcoal, air pressure, oxygen concentration, humidity, spark size/energy.
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He certainly didn't do a series of experiments at different temperatures and show that there was a change in behaviour at 40C.
Is there any other way to support a statement that flash point of charcoal is 40C?
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You really don't understand what a flash point is, do you?
Why not just google it?
First entry of google search :
The flash point is the lowest temperature at which a volatile substance evaporates to form an ignitable mixture with air in the presence of an igneous source and continues burning after the trigger source is removed.
What's important about knowing the flash point of a substance is to know if a process or storage involving it is safe from fire hazard. Getting the incorrect information may lead to loss of lives or assets, or loss of business opportunity.
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Does it mean that it can't be ignited even in elevated temperature?
No that would be an unbelievably stupid thing to say, since it is used as a fuel.
Does sugar have a flash point?
Do the experiment , and find out.
Some datasheets state that flash point of sugar is N/A (not available or not applicable) or left blank. But we can learn from someone else's mistake.
https://en.m.wikipedia.org/wiki/2008_Georgia_sugar_refinery_explosion
The 2008 Georgia sugar refinery explosion was an industrial disaster that occurred on February 7, 2008, in Port Wentworth, Georgia, United States. Fourteen people were killed and forty injured when a dust explosion occurred at a sugar refinery owned by Imperial Sugar. Dust explosions had been an issue of concern among United States authorities since three fatal accidents in 2003, with efforts made to improve safety and reduce the risk of recurrence.
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If I use a charcoal furnace and after I use it to melt something but I want to annael it for couple days inside the charcoal furnace, what insulation material is best at containing the heat for a long period of time without loosing heat?
Or if I ask it another way what charcoal foundry insulation material is best for preserving the heat inside the foundry for a long time?
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You asked me; why not him?
Why are you still asking me about something which someone else wrote, and which is clearly wrong?
This video uses coal dust instead of charcoal dust, but I think it can represent my point.
I think most solids ability to combust is down to their fineness.
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He certainly didn't do a series of experiments at different temperatures and show that there was a change in behaviour at 40C.
Is there any other way to support a statement that flash point of charcoal is 40C?
PLWASE JUST FIND OUT WHAT "FLASH POINT" MEANS!
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If I use a charcoal furnace and after I use it to melt something but I want to annael it for couple days inside the charcoal furnace, what insulation material is best at containing the heat for a long period of time without loosing heat?
Or if I ask it another way what charcoal foundry insulation material is best for preserving the heat inside the foundry for a long time?
If you want to keep it hot for days then you either need incredibly good insulation or a really big furnace, or you have to keep feeding the furnace.
I don't think annealing usually takes that long.
The best lagging that you can easily get is probably rockwool.
If you want something more robust you can use perlite, glued together with sodium silicate, but that's only good up to about 700C if i remember rightly.
I have seen stuff on the net about mixing fire cement or fire clay with vermiculite.
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PLWASE JUST FIND OUT WHAT "FLASH POINT" MEANS!
Since you asked politely,
First entry of google search :
The flash point is the lowest temperature at which a volatile substance evaporates to form an ignitable mixture with air in the presence of an igneous source and continues burning after the trigger source is removed.
If you think you have a better definition, please let me know. What makes you think that it's better than google's answer above?
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Thanks Bored Chemist. I have learned so much from you
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If you think you have a better definition, please let me know. What makes you think that it's better than google's answer above?
I didn't ask you to quote it, I asked you to understand it.
Once you do, you will be able to answer your own questions about it.
I keep making this point- you should try leaning science.
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I didn't ask you to quote it, I asked you to understand it.
How would you know when I understand it?
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Once you do, you will be able to answer your own questions about it.
I keep making this point- you should try leaning science.
How would I know if my understanding is correct?
I also suggest you to keep learning science.
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How would I know if my understanding is correct?
Because you believe nonsensical claims that you read on the internet- such as the idea that charcoal has a flash point.
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How would you know when I understand it?
Because you would apologise for your absurd mistake.
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The flash point is the lowest temperature at which a volatile substance evaporates to form an ignitable mixture with air
Does charcoal evaporate at 40C (or even at 400C)?
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The flash point is the lowest temperature at which a volatile substance evaporates to form an ignitable mixture with air
Does charcoal evaporate at 40C (or even at 400C)?
https://www.fao.org/3/x5328e/x5328e0b.htm#10.1.2.%20volatile%20matter%20other%20than%20water
The volatile matter other than water in charcoal comprises all those liquid and tarry residues not fully driven off in the process of carbonization. If the carbonization is prolonged and at a high temperature, then the content of volatiles is low. When the carbonization temperature is low and time in the kiln is short, then the volatile matter content increases.
These effects are reflected in the yield of charcoal produced from a given weight of wood. At low temperatures (300°C) a charcoal yield of nearly 50% is possible. At carbonization temperatures of 500-600°C volatiles are lower and retort yields of 30% are typical. At very high temperatures (around 1000°C) the volatile content is almost zero and yields fall to near 25%. As stated earlier, charcoal can reabsorb tars and pyroligneous acids from rain wash in pit burning and similar processes. Thus the charcoal might be well burned but have a high volatile matter content due to this factor. This causes an additional variation in pit burned charcoal in wet climates. The resorbed acids make the charcoal corrosive and lead to rotting of jute bags - a problem during transport. Also it does not burn cleanly.
The volatile matter in charcoal can vary from a high of 40% or more down to 5% or less. It is measured by heating away from air, a weighed sample of dry charcoal at 900°C to constant weight. The weight loss is the volatile matter. Volatile matter is usually specified free of the moisture content, i.e. volatile matter - moisture or (V.M. - moisture).
High volatile charcoal is easy to ignite but may burn with a smoke flame. Low volatile charcoal is difficult to light and burns very cleanly. A good commercial charcoal can have a net volatile matter content - (moisture free) of about 30%. High volatile matter charcoal is less friable than ordinary hard burned low volatile charcoal and so produces less fines during transport and handling. It is also more hygroscopic and thus has a higher natural moisture content.
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The flash point is the lowest temperature at which a volatile substance evaporates to form an ignitable mixture with air
Does charcoal evaporate at 40C (or even at 400C)?
https://www.fao.org/3/x5328e/x5328e0b.htm#10.1.2.%20volatile%20matter%20other%20than%20water
The volatile matter other than water in charcoal comprises all those liquid and tarry residues not fully driven off in the process of carbonization. If the carbonization is prolonged and at a high temperature, then the content of volatiles is low. When the carbonization temperature is low and time in the kiln is short, then the volatile matter content increases.
These effects are reflected in the yield of charcoal produced from a given weight of wood. At low temperatures (300°C) a charcoal yield of nearly 50% is possible. At carbonization temperatures of 500-600°C volatiles are lower and retort yields of 30% are typical. At very high temperatures (around 1000°C) the volatile content is almost zero and yields fall to near 25%. As stated earlier, charcoal can reabsorb tars and pyroligneous acids from rain wash in pit burning and similar processes. Thus the charcoal might be well burned but have a high volatile matter content due to this factor. This causes an additional variation in pit burned charcoal in wet climates. The resorbed acids make the charcoal corrosive and lead to rotting of jute bags - a problem during transport. Also it does not burn cleanly.
The volatile matter in charcoal can vary from a high of 40% or more down to 5% or less. It is measured by heating away from air, a weighed sample of dry charcoal at 900°C to constant weight. The weight loss is the volatile matter. Volatile matter is usually specified free of the moisture content, i.e. volatile matter - moisture or (V.M. - moisture).
High volatile charcoal is easy to ignite but may burn with a smoke flame. Low volatile charcoal is difficult to light and burns very cleanly. A good commercial charcoal can have a net volatile matter content - (moisture free) of about 30%. High volatile matter charcoal is less friable than ordinary hard burned low volatile charcoal and so produces less fines during transport and handling. It is also more hygroscopic and thus has a higher natural moisture content.
Was that a yes or a no?
I suspect that you just cut and pasted something because you don't understand it well enough to answer the question.
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Was that a yes or a no?
The article tells that a charcoal is not a homogenous chemical substance. It contains volatile parts which are easier to evaporate than the solid part.
Your question is like asking if a wet cloth evaporates at 40C.
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Was that a yes or a no?
The article tells that a charcoal is not a homogenous chemical substance. It contains volatile parts which are easier to evaporate than the solid part.
Your question is like asking if a wet cloth evaporates at 40C.
No.
It is like asking if a wet cloth evaporates at -40C.
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Do you accept that powdered charcoal forms an ignitable mixture with air in the presence of an igneous source and continues burning after the trigger source is removed?
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Do you accept that powdered charcoal forms an ignitable mixture with air in the presence of an igneous source and continues burning after the trigger source is removed?
If it's hot enough, yes.
Obviously it does.
Do you think that is due to formation of "charcoal vapour" at a temperature near 40C, or do you think it's because the small particles are easily heated to a temperature high enough for the particles to react with air, even though they are not in the vapour phase?
Incidentally, your video shows the answer- look at the colour of the "flash".
Also, are you aware that you can get mists of high- flash-point oils to ignite at temperatures well below their flash points?
https://www.icheme.org/media/9045/xxiii-paper-43.pdf
By the way, why do you use the word "igneous"?
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Incidentally, if one of the mods can be bothered to split out the efforts to explain flash points to hamdani yusuf from the stuff about charcoal furnaces, that would improve the quality of the thread.
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If for example, a homemade charcoal foundry like the attached photo, if another hairdryer is connected and turned on on the other side so is 2 hairdryers are blowing on the charcoal, what do you think the maximum ot top temperateure willl be reached inside? By guessing. 1300 C? 1600 c?