Composition of coal, what is the composition of coal?

The main elements that make up the organic matter of coal are carbon, hydrogen, oxygen, nitrogen and sulfur, in addition, there are very small amounts of phosphorus, fluorine, chlorine and arsenic. Carbon, hydrogen and oxygen are the main bodies of organic matter in coal, accounting for more than 95; The deeper the degree of coalification, the higher the carbon content and the lower the hydrogen and oxygen content. Carbon and hydrogen are the elements that produce heat during the combustion of coal, and oxygen is the combustion supporting element.

When coal is burned, nitrogen does not produce heat and is converted into nitrogen oxides and ammonia at high temperatures, which are precipitated in a free state. Sulfur, phosphorus, fluorine, chlorine and arsenic are harmful components in coal, with sulfur being the most important. When coal is burned, most of the sulfur is oxidized into sulfur dioxide (SO2), which is emitted with flue gas, polluting the atmosphere, endangering the growth of animals and plants and human health, and corroding metal equipment; When sulfur-rich coal is used for metallurgical coking, it also affects the quality of coke and steel.

Therefore, the "sulfur" content is one of the important indicators to evaluate the quality of coal.

The flammable gas produced by the thermal decomposition of organic matter in coal at a certain temperature and under certain conditions is called "volatile matter", which is a mixture of various hydrocarbons, hydrogen, carbon monoxide and other compounds. Volatile matter is also the main coal quality index, and it has an important reference role in determining the processing and utilization methods and process conditions of coal. Coal with a low degree of coalification has more volatile matter.

If the combustion conditions are not appropriate, coal with high volatile content is easy to produce unburned carbon particles when burned, commonly known as "black smoke"; It also produces more pollutants such as carbon monoxide, polycyclic aromatic hydrocarbons, and aldehydes, and reduces thermal efficiency. Therefore, it is necessary to select appropriate combustion conditions and equipment according to the volatile matter of coal.

The content of inorganic substances in coal is very small, mainly water and minerals, and their presence reduces the quality and utilization value of coal. Minerals are the main impurities of coal, such as sulfides, sulfates, carbonates, etc., most of which are harmful components.

"Moisture" has a great impact on the processing and utilization of coal. When the water is burned, it becomes steam to absorb heat, thus reducing the calorific value of the coal. The moisture in coal can be divided into external moisture and internal moisture, and the internal moisture is generally used as an index to evaluate the quality of coal.

The lower the degree of coalification, the larger the internal surface area of the coal and the higher the moisture content.

"Ash" is the solid residue left after the complete combustion of coal, which is an important indicator of coal quality. The ash mainly comes from the non-combustible minerals in coal. When the mineral is burned and ashed, it needs to absorb heat, and a large amount of slag discharge needs to take away the heat, so the higher the ash content, the lower the thermal efficiency of coal combustion; The more ash content, the more ash produced by coal combustion and the more fly ash is emitted.

In general, the ash content of high-quality coal and washed coal is relatively low.

The organic matter in coal is a complex polymer organic compound, which is mainly composed of carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus, and the sum of carbon, hydrogen and oxygen accounts for more than 95% of the organic matter. The inorganic matter in coal also contains small amounts of carbon, hydrogen, oxygen, sulfur and other elements. Carbon is the most important component of coal, and its content increases with the deepening of coalification. The carbon content in peat is 50 60, lignite is 60 70, bituminous coal is 74 92, and anthracite is .

90％～98％。Sulfur is the most harmful chemical component of coal. When coal is burned, sulfur generates SO2, which corrodes metal equipment and pollutes the environment. The sulfur content in coal can be divided into:

Grade: high sulfur coal, greater than 4; Sulfur-rich coal, for; Medium sulphur coal, for; Low-sulphur coal, for; Extra-low sulfur coal.

Less than or equal to 1. Sulfur in coal can be divided into two categories: organic sulfur and inorganic sulfur.

Coal is an important energy source and an important raw material for the metallurgical and chemical industries. It is mainly used for combustion, coking, gasification, low-temperature dry distillation, hydrogenation liquefaction, etc. Burn.

Coal is an important energy resource for human beings, and any coal can be used as an industrial and civil fuel. Coking. The organic matter in the coal is gradually decomposed with the increase of temperature, and the volatile substances in the coal escape in the gaseous or vapor state to become coke oven gas and coal tar, while the non-volatile solid residue is coke.

Coke oven gas is a fuel and an important chemical raw material. Coal tar can be used to produce fertilizers, pesticides, synthetic fibers, synthetic rubber, paints, dyes, medicines, explosives, etc. Coke is mainly used in blast furnace ironmaking and casting, and can also be used to make nitrogen fertilizer and calcium carbide.

Calcium carbide is a synthetic chemical product such as plastics, synthetic fibers, and synthetic rubber. Gasification. Gasification refers to the conversion of gas into gas that can be used as an industrial or domestic fuel and as a raw material for chemical synthesis.

Low temperature dry distillation. Put coal or oil shale in.

At a temperature of about 550 °C, low-temperature dry distillation can produce low-temperature tar and low-temperature coke oven gas, which can be used to make high-grade liquid fuels and as chemical raw materials. Hydroliquefaction. Coal, catalyst and heavy oil are mixed together, the organic matter in the coal is destroyed at high temperature and high pressure, and the hydrogen is converted into low-molecular-weight liquid and gaseous products, and liquid fuels such as gasoline and diesel are further processed.

The raw coal for hydroliquefaction is mainly lignite, long-flame coal and gas coal.

Coal is mainly composed of elements such as carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus.

The carbon in coal does not exist in an elemental state, but part of it is combined with hydrogen, oxygen, sulfur, etc. to form volatile complex compounds, and the rest (the remaining part of the carbon after the volatile compounds are precipitated by coal) is called fixed carbon. Fixed carbon is only burned at high temperatures. The higher the fixed carbon content in coal (e.g., anthracite), the less likely it is to catch fire and burn, and the slower it burns and the flame is shorter.

The use of coal is contraindicated.

To buy stoves and standard coal from formal channels, the heating coal stove should be equipped with a chimney, the chimney connection should be closed with adhesive tape, and the chimney structure should be kept tight to prevent smoke leakage and smoke pouring, and the chimney sticking out of the window should be equipped with a windproof cap.

After adding coal, the furnace lid should be covered in time, and before going to bed, be sure to check whether the furnace fire is sealed and whether the damper is open to prevent the emission of toxic gases.

When using stoves for heating, you must open the windows before going to bed to keep the room ventilated to prevent carbon monoxide poisoning, and it is strictly forbidden to use braziers indoors to burn coal for heating to prevent carbon monoxide poisoning.

The above content refers to Encyclopedia - Coal.

There are two types of composition analysis of coal, industrial composition analysis and chemical composition analysis.

Industrial composition analysis: volatile matter, fixed carbon, moisture, ash.

Chemical composition analysis: carbon, hydrogen, oxygen, nitrogen, sulfur, moisture, ash.

The composition indexes generally include: calorific value (qnet, ar), total sulfur (ST, D%), ash (AD%), volatile content (VD%), total moisture (MT%), fixed carbon (FC), and coke slag characteristics.

Volatile matter. It is the primary indicator to determine the fire characteristics of coal. The higher the volatile content, the easier it is to catch fire.

According to the boiler design requirements, the value of volatile matter for coal supply should not change too much, otherwise it will affect the normal operation of the boiler. For example, after the original design uses low volatile coal and changes to high volatile coal, the furnace may be shut down due to the burning of the injector due to the fact that the center of the flame is close to the outlet of the injector; If the original design uses high volatile coal and changes to low volatile coal, the combustion will be incomplete due to too late ignition, and even cause a flameout accident. Therefore, when supplying coal, it is necessary to try to according to the original design of volatile coal type or similar coal type**.

Ash content. The ash content will reduce the flame propagation speed, delay the ignition time, unstable combustion, and reduce the furnace temperature.

Moisture content. Moisture is one of the harmful substances in the combustion process, it absorbs a lot of heat during the combustion process, and the impact on combustion is much greater than ash.

Calorific value. The calorific value is an important basis for boiler design. Because the pulverized coal in the power plant has strong adaptability to the type of coal, as long as the calorific value of the coal is roughly consistent with the design requirements of the boiler.

Ash melting point. Because the core temperature of the furnace flame of the pulverized coal furnace is more than 1500, at such a high temperature, the coal ash is mostly in a soft or fluid state.

Sulfur content of coal. Sulfur is a harmful impurity in coal, although it has no effect on the combustion itself, but its content is too high, and the corrosion of equipment and environmental pollution are quite serious. Therefore, the sulfur content of coal used in power plants should not be too high, and the general requirement should not be exceeded.

Composition of coal: It is mainly composed of elements such as carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus. Coal is a solid flammable mineral that was gradually formed by ancient plants buried in the ground and undergoing complex biochemical and physicochemical changes.

Coal as a fuel has been around for as early as 800 years. Coal is widely used as a fuel for industrial production and began with the Industrial Revolution at the end of the 18th century. With the invention and use of the steam engine, coal was widely used as a fuel for industrial production, bringing unprecedented huge productivity to the society, promoting the development of industry, and then developing coal, steel, chemical, mining, metallurgical and other industries.

In addition to the use of coal as fuel to obtain heat and kinetic energy, it is more important to produce coke for metallurgy and artificial oil, that is, coal tar, a liquid product of low-temperature dry distillation of coal.

Coal is known as black gold, industrial food, it is one of the main energy sources used by the human world since the eighteenth century, since the beginning of the twenty-first century, although the value of coal is not as good as before, but after all, coal is still one of the indispensable energy of our human production and life for a long time in the present and future.

Coal is the most abundant and widely distributed fossil fuel on the planet. The main elements that make up the organic matter of coal are carbon, hydrogen, oxygen, nitrogen and sulfur, and in addition to this section, there are also very small amounts of phosphorus, fluorine, chlorine and arsenic.

The main components of coal are carbon, hydrogen, oxygen and small amounts of nitrogen, sulfur or other elements. Sulphur is one of the most important impurities in coal, which usually occurs in the form of sulfides in the combustion products of coal. In some countries, such as the United States, there are regulations to control sulfide emissions, and because the cost of removing such harmful impurities is not low, the production of low-sulfur coal is rewarded to reduce pollution.

Coal is thought to have been formed by the burial of ancient plant remains under the strata by the conversion of peat, lignite, bituminous coal, and anthracite into rubber, and anthracite can be further converted into graphite.

1. The basic composition of coal

Coal is mainly composed of organic matter, which contains a large amount of carbon elements. In addition to carbon, coal also contains small amounts of elements such as hydrogen, oxygen, nitrogen, and sulfur, as well as impurities such as ash and moisture.

2. The formation process of coal

Deposition of plant debris: Coal is deposited from ancient plant debris in lakes, swamps, and other environments. These plant remains are mainly woody and fibrous plants. Humus transformation: plant residues are gradually converted into humus after compaction.

In this process, some elements from the plant are gradually eliminated to form carbon-rich humus. Coalification process: As the deposition and compaction of the formation increases, humus is further converted into coal.

In this process, the chemical bonds between humus molecules are broken, and the carbon element gradually accumulates to form the bulk of coal. or count.

3. Classification of coal

Lignite: It is a type of coal with the lowest degree of coalification, with low carbon content and high moisture, generally brown or dark brown. Bituminous coal:

It is a type of coal with a high degree of coalification, with high carbon content and low moisture, and is often used in power generation and metallurgy. Anthracite: It is a type of coal with the highest degree of coalification and the highest carbon content, and it produces very little smoke when burned.

It is commonly used in chemical and advanced processing fields.

4. The chemical composition of coal

The chemical composition of coal is complex, and there are mainly the following parts: fixed carbon: the main component in coal, which is an important form of carbon in coal.

Volatile matter: the volatile part of coal, including moisture, volatile matter and coke particles. Ash content.

The general term for non-combustible substances in coal, mainly inorganic salts and minerals contained in coal. Sulfur: The content of sulfur contained in coal, and high-sulfur coal will produce harmful gases such as sulfur dioxide when burned.

5. The use of coal

Coal is an important energy resource that is widely used in various fields. The main uses include power generation, metallurgy, chemical industry, building materials, etc. In addition, coal can also be used for coking, making activated carbon, extracting coal tar, etc.

To sum up, the main component of coal is carbon, which is formed by geological processes from ancient plant remains. The composition and classification of coal are of great significance for the study of coal properties, the process of coal utilization, and environmental protection.