How is combustion composed?

Combustion is the process of rapid oxidation of objects, producing light and heat. Combustion is necessary for the coexistence of three things to occur, namely combustibles such as fuel, combustibles such as oxygen and temperature to reach the ignition point - heat, called the three elements of combustion - fire triangle. Burning conditions:

There are combustibles Combustion, combustibles reach the ignition point, and they come into contact with oxygen (air) A violent oxidation reaction between combustibles and oxygen in the air is called combustion. Usually the combustion is to be attended by oxygen, but in some special cases the combustion can be carried out under oxygen-free conditions, such as hydrogen combustion in chlorine, magnesium strips in carbon dioxide, etc. Broad definition of combustion:

Combustion refers to any violent chemical reaction that emits heat and heat, and does not necessarily require oxygen to participate, such as the reaction of magnesium metal and carbon dioxide to form magnesium oxide and carbon, which does not involve oxygen, but is a violent chemical reaction that emits heat and heat, and also belongs to the category of combustion.

It's a condition for burning! The following three basic conditions must be met for the combustion of substances: (1) Combustibles:

Regardless of solids, liquids and gases, any substances that can react violently with oxygen or other oxidants in the air are generally combustible substances, such as wood, paper, gasoline, alcohol, gas, etc. (2) Combustibles: Any substance that can help and support combustion is called combustibles.

Generally refers to oxygen and oxidants, mainly referring to oxygen in the air. This oxygen is called air oxygen and accounts for about 21% of the air. Combustible substances do not burn without oxygen participating in the compound.

For example, 10-12 cubic meters of air are required to burn 1 kg of oil. It takes 4-5 cubic meters of air to burn 1 kg of wood. When there is not enough air**, the combustion will gradually weaken until it is extinguished.

When the oxygen content of the air is less than 14-18%, combustion does not occur. (3) Ignition source: Any energy source that can cause the combustion of combustible substances is called an ignition source, such as open flame, friction, impact, electric spark, etc.

Only when the above three conditions are met can the substance be burned. For example, a stove can only be lit if it has three conditions: wood (combustible), air (combustible), and match (fire source).

When a combustible substance generates a high temperature, it is a high-temperature phenomenon formed with the help of combustible substances such as oxygen.

What I learned in "Fire and Explosion Prevention Technology" is that the conditions for the combustion of substances are combustibles, ignition points (ignition sources) and oxygen. I guess that's how it should be.

Oxygen is not necessarily, as iron can be burned in chlorine.

The concept of combustion is: combustion is a light, heat-rising, violent chemical reaction.

General chemical definition of combustion: combustion is a violent luminous and calcitrant oxidation reaction between combustibles and combustibles. Broad definition of combustion:

Combustion refers to any violent reaction that emits light and heat, and does not necessarily require oxygen to participate. Combustion is divided into: flash ignition, **, ignition, spontaneous combustion.

Combustion conditions: combustibles reach the ignition point. Ignition point, the minimum temperature required for combustion.

Generally, combustion is attended by oxygen, but in some special cases, combustion can be carried out under oxygen-free conditions.

In the process of combustion, the momentum, heat and mass transfer between fuel, oxygen and combustion products are transferred, forming a complex structure of flame with multi-component concentration gradient and non-isothermal two-phase flow.

These transfers in the flame are realized by laminar molecular transfer or turbulent micro-mass transfer, while in industrial combustion devices, turbulent micro-mass transfer is the main focus, and exploring the law of velocity, concentration, temperature distribution in the combustion chamber and the interaction between them is an important part of the study of the combustion process from the perspective of fluid mechanics.

The Three Elements of Combustion:

There are three basic conditions that must be met for combustion to occur: there must be silver balance combustibles, such as wood, natural gas, oil, etc. There should be combustible substances, such as oxygen, potassium chlorate, etc.; There must be a certain temperature, combustibles, oxidants and ignition sources, which are called combustion triads, and combustion occurs when these three elements are present at the same time and interact with each other.

The combustion reaction is one of the earliest chemical reactions recognized by human beings. The combustion reaction theory is one of the earliest chemical theories established by chemists that can explain chemical phenomena in a unified manner. The first stage was in the middle of the 17th century, when phlogiston theory appeared.

Directing chemists to the study of the process of chemical reactions has led to many chemical discoveries.

Combustion is a kind of chemical reaction that emits positive heat and luminescence, and its reaction process is extremely complex, the chain reaction of free radicals is the essence of the combustion reaction, and light and heat are the physical phenomena that occur during the combustion process. Combustibles react with oxygen or air in a rapid exothermic and luminous oxidation reaction and appear in the form of a flame, The combustion of coal, oil and natural gas is the main thermal power of various sectors of the national economy.

Combustion is a kind of exothermic and luminescent chemical reaction, and its reaction process is extremely complex, the chain reaction of free radicals is the essence of the combustion reaction, and light and heat are the physical phenomena that occur during combustion.

The exothermic reaction that occurs when combustibles react with oxidants is usually accompanied by flames, luminescence and/or smoke emitting. Combustion should have three characteristics, namely, chemical reaction, exothermic and luminescence.

The essence of combustion: it is a violent redox reaction, which is the process of electron gain and loss shift.

Necessary conditions for combustion: combustibles (all substances that can cause combustion reactions with oxygen or other oxidants in the air are called combustibles); ignition sources (any external heat source that causes a substance to start combusting); Combustibles [Substances that combine with combustible substances to cause combustion are called combustibles (also known as oxidants).]

Combustion characteristics of solid substances: surface combustion; smoldering; decomposition combustion; Evaporative combustion.

Combustion characteristics of liquid substances: evaporative combustion; power combustion; boiling combustion; Sputter burning.

Combustion characteristics of gaseous substances: diffusion combustion; Premixed combustion.

As the old saying goes, "Man must be real, and fire must be empty". The meaning of this saying is that you must be down-to-earth in order to have a successful career; Combustibles should be more overhead in order to burn more vigorously.

The purpose of "fire to be virtual" is to increase the ignition point of combustibles. Note: Combustion must be an oxidation reaction, and an oxidation reaction is not necessarily combustion;

(1) Diffusion combustion Combustible gas and air molecules diffuse and mix with each other, and their mixed concentration is outside the first range, and it can be ignited and burned when it encounters an ignition source.

2) Evaporative combustion flammable liquids, such as gasoline, alcohol, etc., evaporate to produce vapor that is ignited**, which releases heat to further heat the surface of the liquid, thereby promoting the continuous evaporation of the liquid and continuing the combustion. Naphthalene, sulfur, etc., although they are solid at room temperature, they will sublimate to produce vapor after heating or vapor after melting, which is also evaporative combustion.

3) Decomposition combustion refers to the decomposition of combustibles in the combustion process when first exposed to heat, and the reaction of decomposition products and oxygen produces combustion, such as the combustion of solid combustibles such as wood, coal, and paper.

4) Surface combustion: Combustion is carried out at the contact point between the air and the solid surface. For example, when wood is burned, it will not decompose the combustible gas in the end, only solid charcoal remains, and the combustion is carried out in the contact part between the air and the solid charcoal surface, which can produce a red-hot surface without producing flames.

5) Mixed combustion Combustible gas and combustible gas are fully diffused and mixed in the container or space, and its concentration is within the first range, and combustion will occur when it encounters the fire source, and this combustion is carried out rapidly in the space where the mixed gas is distributed, so it is called mixed combustion.

6) Smoldering Some solid combustibles only smoke and no flame combustion occurs under the conditions of poor air circulation, low heating temperature or more water content of combustibles.

2) Evaporative combustion flammable liquids, such as gasoline, alcohol, etc., evaporate to produce vapor that is ignited**, which releases heat to further heat the surface of the liquid, thereby promoting the continuous evaporation of the liquid and continuing the combustion.

2) Evaporative combustion flammable liquids, such as gasoline, alcohol, etc., evaporate to produce vapor that is ignited**, which releases heat to further heat the surface of the liquid, thereby promoting the continuous evaporation of the liquid and continuing the combustion.

3. Decomposition combustion: It refers to the decomposition of combustibles in the combustion process when they are first heated, and the decomposition products are burned after the reaction with oxygen, such as the combustion of solid combustibles such as wood, coal, and paper;

4. Surface combustion: the combustion is carried out in the contact part between the air and the solid surface, such as the burning of wood, and finally only the solid charcoal is left, and the combustion is carried out in the contact part between the air and the solid charcoal surface, which can produce a red-hot surface, but does not produce flames;

5. Mixed combustion: combustible gas and combustible gas are fully diffused and mixed in the container or space, and their concentration is within the first range, and combustion will occur when encountering the fire source, and this combustion is carried out rapidly in the space where the mixed gas is distributed, so it is called mixed combustion.

There are five types of combustion: diffusion combustion, evaporative combustion, decomposition combustion, surface combustion, and mixed combustion.

The simple definition of combustion is the oxidation reaction with heat and light, and it is usually called combustion when the reaction speed is high speed and the reaction heat is large and there is a luminescence phenomenon. Combustion is often carried out in the form of gas, such as liquid heavy oil, solid wood, coal, etc., before combustion, it needs to be evaporated or heated to decompose to produce a variety of flammable gases, which form a flammable mixture with air, and burn when there is an ignition source.