Without the burning of a flame, the flame may burn in the air

According to the definition of fire engineering:

Smoldering is the burning without a flame, such as coal that has been burning underground for hundreds of years before it is mined.

Cotton is extinguished, but only the surface is extinguished, and the inside is still smoldering, so we should pay special attention to this category in fire engineering.

A Ph.D. from the University of Science and Technology of China gave us this lesson.

does not exist. Definition of combustion:

Combustion is the process of rapid oxidation of objects, producing light and heat.

The so-called flame is the apparent phenomenon of gas burning.

Therefore: all substances with high boiling points are (strictly speaking, they do not react with oxidants to produce combustible gases during the reaction, for example: carbon is generally regarded as a substance that does not produce flames when burned, but in fact, when it is burning, if there is not enough oxygen, carbon monoxide will be produced, so the flame can be observed in many occasions when carbon elements are burned, in fact, it is the flame produced by carbon monoxide combustion.

For example: iron, magnesium, aluminum, silicon, 、..

Other solids, such as paraffin wax and sulfur, are vaporized during combustion to produce flames.

If iron, magnesium, etc. are turned into vapor at high temperatures, and then re-combusted, flames will also be generated.

Whether there is a flame in the combustion of a substance depends on whether the substance can volatilize at room temperature or after heating, and if it can be volatile, the particles of the substance will be dispersed into a small area in the air, and the flame can be seen when burning. Charcoal, magnesium bars, wire is not flame burning.

In general, gaseous substances are burned with flames, while solid substances burn without flames and emit light.

For example, hydrogen, methane, and carbon monoxide are burned with a light blue flame and a blue flame, respectively.

Although sulfur is a solid, it melts first and then volatilizes into sulfur vapor when burned, so it burns in the air with a faint light blue flame and a bright blue-purple flame in oxygen.

Solid substances, such as charcoal, iron wire, magnesium belts, etc., are burned, respectively, glowing white, sparkling, and dazzling.

Phosphorus appears to be white smoke and no flame.

There is no flame when charcoal burns.

We see carbon burning because it contains impurities, which transpire to form a flame when heated!

Charcoal is recommended, the kind that burns in the air is of very good quality, and the flame is the least noticeable.

Hydrogen is also available, and the flame is also very light.

To say that there is no color at all, brightness is impossible!

Because combustion is originally a redox reaction that emits light and heat.

Flames are produced by the combustion of flammable gases or vapors; (During combustion, there will be a transition and transfer of electrons, and a part of the energy will be released in the form of visible light.) ）

For example, a piece of charcoal burns to produce a flame because the charcoal contains wood tar, and the wood tar turns into steam when heated, and these steam is burned again to produce a flame.

If a pile of charcoal is burned, the cause of the flame is not only the reason that the charcoal contains wood tar, but also because of the flammable gas CO, CO is burned again to produce a flame; Chemical formula: C+O2==Ignition==CO2, C+CO2== High Temperature==2Co, 2CO+O2==Ignition==2CO2 (Flame).

There is no flame in solid combustion, so why do sulfur and magnesium burn but also see flames?

This is because the melting point of these substances is relatively low, and when the heating begins, or the heat released by the reaction causes the solids to melt and produce S or Mg vapor, these vapors burn to produce flames.

Summary. Three factors of combustion. 1.

Must be combustible. 2.The temperature must reach the ignition point.

3.Must be in contact with oxygen or air. Detailed addition:

Combustion refers to the exothermic reaction between combustibles and oxidants, usually accompanied by flames, luminescence and smoke.

Three factors of combustion. 1.Must be combustible.

2.The temperature must reach the ignition point. 3.

Must be in contact with oxygen or air. Detailed chain charging: Combustion refers to the exothermic reaction between combustibles and Kaishangsun oxygen retarders, usually accompanied by flames, luminescence and smoke.

What substances can be burned: 1. Some non-metallic elements, such as carbon, sulfur, phosphorus, and silicon; 2. Most of the voltaic metal elements, such as sodium, magnesium, potassium and lithium; 3. Some gaseous hydrides, such as hydrogen sulfide and methane; 4. A small amount of oxides, such as carbon monoxide; 5. The vast majority of organic matter, such as methyl aluminol, propylene deficient ketone, and oil.

The difference is: the combustion products after combustion no longer contain combustible substances, that is, there is no remaining solid combustible matter in the ash slag, and when there is no combustible gas in the flue gas, it is called complete combustion.

When there are still remaining combustibles in the combustion products after combustion, it is called incomplete combustion.

Combustibles undergo a rapid exothermic and luminescent oxidation reaction with oxygen or air and appear in the form of a flame. The combustion of coal, oil, and natural gas is the main thermal energy power of all sectors of the national economy. The rapid increase in energy demand and the rapid development of aerospace technology in modern times have promoted the combination of fluid mechanics, chemical reaction kinetics, and heat and mass transfer, which has led to the rapid development of combustion science. On the other hand, the development of fire prevention technology for the purpose of eliminating combustion has also promoted the research of combustion theory.

During combustion, the fuel, oxygen, and combustion products transfer momentum, heat, and mass transfer to form a flame, a complex structure with multi-component concentration gradients and non-isothermal two-phase flows. These transfers within the flame are achieved by laminar molecular transfer or turbulent micromass transfer, while industrial combustion units are dominated by turbulent micromass transfer. Exploring the distribution of velocity, concentration, and temperature in the combustion chamber and their interaction is an important part of the study of the combustion process from the perspective of fluid mechanics.

Due to the complexity of the combustion process, experimental technology is the main means of combustion engineering. Computational combustion, which has been developed in recent years, has made significant progress in the study and charging of engineering problems such as the flow field in combustion equipment, the ignition of fuels and the process of heat transfer in combustion, and the stability of flames by establishing physical models of combustion processes to solve differential equations such as momentum, energy, and chemical reactions.

The combustion of a substance is not simply the reaction of a substance with an oxidizing agent.

If there is a flame to be generated, a very important condition is that the reactants are volatile or gaseous, or the reactants can form volatile or gaseous intermediate substances after a certain reaction.

For example, gasoline is volatile, so after gasoline is ignited, a part of gasoline vaporizes and burns at the same time, producing a flame.

Also: the combustion of carbon, part of which produces carbon monoxide in a gaseous state, reacts with oxygen to form a flame.

The counter-example is the combustion of iron: although the reaction is extremely violent, no gaseous reactants or intermediates are formed, so there is only spark and no flame.

1. Flameless combustion, also known as dark fire, cannot produce flames when burning. Flameless burning can be enlisted in the army, accounting for only 6 to 10 percent of forest combustibles, such as peat, humus, and rotten wood.

2. The characteristics of flameless combustion are: slow spreading, long duration, and the heat generated accounts for more than 50% of its own heat content, so peat can still continue to burn in the case of wetness. Flameless combustion belongs to the incense type, which mainly relies on ion vibration and balance to transfer heat.

If the fire is extinguished by wind power, it can only blow bigger and bigger, and can only be used to fight, bury with sand, irrigate with water and open the burning without peeling off, etc., to reduce the oxygen content, destroy the ion vibration heat transfer, and achieve the purpose of extinguishing the fire.

3. Flame combustion, also known as open flame, that is, the basic form of flame can be produced when burning. Flame-burning combustible weapons account for 85 to 90 percent of forest combustibles, such as weeds, dead branches, fallen leaves, tree trunks, branches, felling residues, lichens, mosses, etc.

4. Flame burning is a candle type combustion, to extinguish it, as in the same way as the incendiary bullet candle, you can take the method of wind blowing and fluttering to reduce the content of combustible gases and extinguish the fire.