It
is a little known fact that only carbon monoxide and vaporised carbon actually burn, in a wood fire. I didn't mention hydrogen, but a certain poorly thought out pigment mix (basically thermite) used on a famously disastrous German Zeppelin stopped people using hydrogen gas for lift in balloons, but it is also a part of hydrocarbon combustion also, including wood, coal, oil or gas.
Hydrogen actually burns so fast that the sound you get when you burn it makes a similar sound as pulling a cork out of a test tube, from gas generated chemically like zinc or magnesium and hydrochloric acid.
But breaking down cellulose is not a heat generating business. Or more precisely, the heat generated is very small. The flames are a mix of burning carbon gas, carbon monoxide and a tiny bit of hydrogen though much of it just turns into water directly in the oxidation reaction. Oxygen and heat are required to get these exothermic end products. But they do not produce enough heat to drive a chain reaction.
Same with liquid fuels. Only boiled vapour ignites. This can be achieved with vacuum or disperser sprays, but it is only gaseous liquid fuels that burn. Again, you can oxidise them, but the reaction is not hot enough in most cases. Rocket fuel systems use a liquid or solid oxidiser for providing oxygen but the fuel has to boil first. Hydrogen is more present with hydrocarbons, and produces water vapour.
There is even methods to convert solid fuels into gas, and they all require heat and/or pressure.
In gases, pressure and heat are related. Boyles law is pressure equals the inverse of volume, when temperature is unchanged. However, heat increases pressure and so does decreasing volume. But conversely, vacuum can make a liquid boil at a lower temperature.
Combustion only occurs in the gas phase. Some liquid phase reactions produce heat and the most famous are explosives and rocket fuels and especially detonators. They increase pressure which lowers the required heat to begin a chain reaction, burning gas mixtures.
But, basically, only gases burn.
We can't stop here! This is Whale country!
Loki was born in Australia, now is wandering Amsterdam again after 9 months in Sofia, Bulgaria. IT generalist, physics theorist, futurist and cyber-agorist.
Loki's life mission is to establish a secure, distributed layer atop the internet, and enable space migration, preferably while living in a beautiful mountain house somewhere with a good woman, and lots of farm animals and gardens, where he can also go hunting and camping.
All images in the above post are either original from me, or taken from Google Image Search, filtered for the right of reuse and modification, and either hotlinked directly, or altered by me.