What are the types of coal. Choosing coal for a solid fuel boiler: which coal is better for heating a house? What grade of coal is best for heating a house

Grade A (anthracite).
Anthracites combine coal with a vitrinite reflectance of more than 2.59%. With a volatile matter yield of less than 8%, anthracites also include coals with a vitrinite reflectance of 2.2 to 2.59%. The bulk of anthracite is used for energy purposes. Medium and large classes of them serve as smokeless fuel in the domestic sector. Part of the anthracites is directed to the production of thermoanthracite, which, in turn, is used as the main carbonaceous filler in the manufacture of cathode blocks for electrolyzers in the aluminum industry. Anthracites are also used for the production of silicon carbide and aluminum carbide.

Mark D (long-flame).
Long-flame coal are coals with a vitrinite reflectance from 0.4 to 0.79% with a volatile matter yield of more than 28-30% with a powdery or slightly caking non-volatile residue. Long-flame coals do not sinter and are classified as thermal coals. Directions for the use of these coals are energy and municipal fuels, therefore their most significant characteristic is the heat of combustion. When moving to the next brand of DG, the calorific value of coal increases significantly. Studies have shown that long-flame coal with a low ash content can serve as a good raw material for the production of synthetic liquid fuels and chemical products, the production of molded coke and spherical absorbents, and low-temperature (up to 700 degrees) coking.

Brand DG (long-flame gas).
Long-flame gas coals are coals with a vitrinite reflectance of 0.4 to 0.79% with a volatile matter yield of more than 28-30% with a powdery or slightly caking non-volatile residue. These coals are transitional between coals of grades D and G. They differ from long-flame coals in the presence of sintering (the thickness of the plastic layer is 6-9 mm, and from gas coals with similar sintering properties - more insignificant brittleness and increased mechanical strength. The latter circumstance determines the predominance of coarse coals among such coals). - middle classes DG grade coal is also referred to the group of energy coals, they are not suitable for participation in coke charges, because the resulting coke is characterized by low mechanical strength and increased reactivity.

Mark G (gas).
Coal gas has two technological groups. Vitrinite coals (vitrinite reflectance from 0.5 to 0.89%) with a volatile matter yield of 38% or more, with a plastic layer thickness of 10 to 12 mm form group 1G, vitrinite and inertinite coals with a vitrinite reflectance of 0.8 - 0.99%, the yield of volatile substances is 30% and higher and the thickness of the plastic layer is from 13 to 16 mm form group 2G. . Gas coals are mainly used as energy and domestic fuels. Group 2G coal with a plastic layer thickness of more than 13 mm is used for coking. The limited possibility of using gas coals in the charges of coking plants producing metallurgical coke is due to the fact that during layered coking they cause the formation of microcracks in the coke, which significantly reduce its strength. Gas coal with a plastic layer thickness of 8-12 mm is used for the production of molded coke and spherical absorbents, and coals with a plastic layer thickness of less than 8 mm are used for gasification and semi-coking. Vitrinite low-ash coal grade G with a volatile matter yield of more than 42% is a good raw material for the production of synthetic liquid fuels.
Mark B (Brown).
Brown coal is characterized by low vitrinite reflectance (less than 0.6%) and high volatile matter (more than 45%). Brown coals are divided depending on the humidity into technological groups: 1B (moisture over 40%), 2B (30-40%), 3B (up to 30%). Brown coals of the Kansk-Achinsk coal basin are mainly represented by group 2B and partially - 3B (vitrinite reflection index 0.27-0.46%), brown coals of the Moscow Region basin belong to group 2B, coals of the Pavlovsky and Bikinsky deposits (Primorsky Territory) belong to group 1B. Brown coal is used as an energy fuel and chemical raw material.

GZhO brand (gas fat lean).
Fatty gas coals, lean in terms of the yield of volatile substances and the thickness of the plastic layer, occupy an intermediate position between coals of grades G and GZh. There are two technological groups. Technological group 1GZhO includes coal with a vitrinite reflection index of less than 0.8% and a volatile matter yield of less than 38%, with a plastic layer thickness of 10 to 16 mm. The 2GZhO group includes coals with a vitrinite reflectance of 0.80-0.99%, a yield of volatile substances of less than 38%, with a plastic layer thickness of 10-13 mm, as well as coals with a vitrinite reflectance of 0.80-0.89% with the yield of volatile substances is 36% or more with a plastic layer thickness of 14-16mm. Humidity grade GZhO fluctuates within 6-8%, ash content - 6-40%. The carbon content varies within 78-85%, hydrogen - from 4.8 to 6.0%, sulfur 0.2-0.8%. GZhO brand coal is characterized by a wide variation in properties, which does not allow us to recommend any one direction for their use. Coal of the 1GZhO group with a plastic layer thickness of less than 13 mm can make up no more than 20% of the charges of coking plants, and only on condition that the rest of the charge contains well-caking coals with a vitrinite reflection index of 1 to 1.5%. Group 2GZhO coal is a good raw material for coking (especially with a vitrinite reflectance of at least 0.85%) and can make up more than half of the charge. Fusinite coal of the 1GZhO group (subgroup 1GZhOF) is completely unsuitable for the production of metallurgical coke, and can be used in the domestic (large classes) or energy (small classes) sectors.

Brand GZH (gas fat).
Fatty gas coals occupy an intermediate position between grades of G and Zh coals and are divided into two groups. Group 1GZh combines coal with a vitrinite reflectance of 0.5-0.79%, a volatile matter yield of 38% or more, and a plastic layer thickness of more than 16 mm. The 2GZh group combines coal with a vitrinite reflectance of 0.8-0.99%, a volatile matter yield of 36% or more, and a plastic layer thickness of 17-25 mm. Grade GZh differs from gas coals in higher caking capacity, and from coals of Zh grade - in a higher yield of volatile substances. GZh grade coals are mainly used in the coking industry and are included in the group of coal grades especially valuable for coking. In most cases, they can completely replace fat coals in the charge of coking plants. It is advisable to use GZh grade coal concentrates with an ash content of less than 2% as a binder in the production of electrode and carbon-graphite products; GZh grade coals are also suitable for the production of synthetic liquid fuels.

Mark J (bold).
Fatty coals are divided into two groups. The first group (1G) includes coal with a vitrinite reflectance of 0.8–1.19%, a volatile matter yield of 28–35.9%, and a plastic layer thickness of 14–17 mm. The second group (2G) includes coals with a vitrinite reflectance of 0.8-0.99%, a volatile matter yield of 36% or more, with a plastic layer thickness of 26 mm or more. The same group includes coals with the same values ​​of the vitrinite reflectance index, but with the release of volatile substances from 30 to 36% with a plastic layer thickness of 18 mm and more. Also, group 2G includes coal with a vitrinite reflectance of 1-1.19% with a volatile matter yield of at least 30% with a plastic layer thickness of at least 18 mm. Coal grade Zh are especially valuable coking coals and are used mainly in coking chemical industry, making up from 20 to 70% of the coke charge. Coke obtained from Zh grade coals has high structural strength.

Brand KZh (coke fat).
Fat coke coals stand out as coal with a vitrinite reflectance of 0.9-1.29%, a plastic layer thickness of 18 mm, with a volatile matter yield of 25-30%. The main consumer of KZh grade coal is the by-product coke industry. Of all the grades of coal used to produce coke, they have the highest coking capacity. High-quality metallurgical coke is obtained from them without mixing with coals of other grades. In addition, they are able to accept up to 20% of filler coal grades KO, KS and OS without changing the quality of coke.

Mark K (Coke).
Coke coal is characterized by a vitrinite reflection index from 1 to 1.29%, as well as good sintering properties. The thickness of the plastic layer is 13-17 mm for coals with a vitrinite reflectance of 1.0-1.29% and 13 mm and higher with a vitrinite reflectance of 1.3-1.69%. The yield of volatile substances is in the range of 24-24.9%. Without mixing them with coals of other grades, they provide conditioned metallurgical coke. The quality of coke can significantly increase when coal grade K is mixed with 20-40% coal grades Zh, GZh and KZh.

Brand KO (coke lean).
Coal lean coke is a coal with a yield of volatile substances close in value to coke coal, but with a thinner plastic layer - 10-12 mm. The reflection index of vitrinite is 0.8-0.99%. Coal grade KO is mainly used for the production of metallurgical coke as one of the filler coals for grades GZh and Zh.

KSN brand (coke weakly caking low metamorphosed).
Low-caking, low-metamorphosed coke coals are characterized by a vitrinite reflection index from 0.8 to 1.09%. When coking without mixing with other coals, they give mechanically low strength, highly abrasive coke. They are used both in the coke industry, and in the power industry and the domestic sector. KSN grade coal can also be used to produce synthetic gas.

Grade KS (Coke weakly caking).
Low-caking coke coals are characterized by low sintering (the thickness of the plastic layer is 6-9 mm with a vitrinite reflectance index of 1.1-1.69%. Coal of the KS grade is used mainly in the coke industry as a lean component. Part of the coal is used for layer combustion in industrial boilers Low-caking coke coals are characterized by low caking capacity (plastic layer thickness 6-9 mm with vitrinite reflectance index 1.1-1.69%. used for stratified combustion in industrial boiler houses and in the domestic sector.

Brand OS (lean sintering).
The lean coals sintering have vitrinite reflection indices from 1.3 to 1.8% and the yield of volatile substances is not more than 21.9%. The thickness of the plastic layer for the 2OS group is 6-7 mm, and for the 1OS group it is 9-12 mm with a vitrinite composition and 10-12 mm with a fusinite composition. Humidity of mined coal grade OS does not exceed 8-10%. Ash content ranges from 7 to 40%. The sulfur content in the Kuznetsk basin does not exceed 0.6%, sometimes it reaches 1.2% in the Karaganda basin, and 1.2-4.0% in the Donbass. The carbon content is 88-91%, hydrogen 4.2-5.%. The main consumer of OS grade coal is the by-product coke industry; these coals are one of the best lean components in coke blends. Some coals of the OS grade even without mixing with coals of other grades give high-quality metallurgical coke; but during coking, they develop a large bursting pressure on the walls of coke ovens, coke is dispensed from the ovens with great difficulty, which leads to a quick failure of the ovens. Therefore, OS grade coal is usually coked in a mixture with G and GZh coals, which have a high degree of shrinkage.

Brand TS (skinny slightly caking).
Lean low-caking coals are characterized by a volatile matter yield of less than 22% and very low sintering (the plastic layer thickness is less than 6 mm. The moisture content of mined coal of the TC grade is low - 4-6%. The ash content is in the range of 6-45%. The carbon content is 89-91%, hydrogen 4.0-4.8%. Sulfur content in coals of Kuzbass 0.3-0.5%, Donbass 0.8-4.5%. mainly in the power industry; large-medium classes of coals of this brand are good smokeless fuel for small boilers and individual domestic use.

Grade SS (low caking).
Weakly caking coals are characterized by a vitrinite reflection index in the range of 0.7-1.79%, a plastic layer thickness of less than 6 mm, and a release of volatile substances, which is characteristic of well-coking coals of Zh, KZh, K, KS and OS grades. Humidity of the mined coal reaches 8-9%. Ash content ranges from 8 to 45%. The sulfur content usually does not exceed 0.8%. The carbon content ranges from 74 to 90%, hydrogen from 4.0 to 5.0%. They are mainly used in large power plants, in industrial boiler houses and in the domestic sector. In a limited amount, certain varieties of SS grade coals are used in batches of coking plants.

Mark T (skinny).
Lean coal is characterized by the release of volatile substances from 8 to 15.9% with a vitrinite reflection index from 1.3 to 2.59%; sintering is absent. They are mainly used in the electric power industry and in the domestic sector; under the condition of low ash content, they can be used to obtain carbonaceous fillers in electrode production.

There is coal for heating three types: brown stone and anthracite. Its marking is carried out using letter designations.

The first letter indicates the brand of coal:

• Brown coal is designated by the letter "B";
• Coal subdivided into:
  • D - long-flame;
  • G - gas;
  • F - fatty;
  • K - coke;
  • T - skinny;
• Anthracite is designated by the letter "A"

The second is its size class (see table):

What kind of coal is used to heat the house?

When deciding which coal is better for heating, anthracite is first of all remembered. This type of coal has the best fuel characteristics in terms of such parameters as minimum consumption, maximum heat transfer, uniform and long burning of each loaded batch, and the minimum amount of slag formed during combustion.

This brand of coal contains less than 1% sulfur and only about 10% ash, which allows us to talk about minimal harm. environment(min emissions of sulfur dioxide) and a significant increase in the life of chimneys and boilers. Sulfur and water vapor, when interacting, form sulfuric and sulphurous acids, which negatively affect the design of chimneys and heating boilers.

The amount of coal you need for the heating season directly depends on its quality.

Anyone who chooses coal for heating, despite all the advantages of anthracite listed above, cannot definitely recommend it, since anthracite has two drawbacks that play an important role for owners of private houses. First, anthracite is the most expensive grade of coal. Secondly, it is extremely difficult to kindle it.

Therefore, most often, for heating a house with coal, preference is given to long-flame coals (WPC), which are well suited for almost any heating boilers operating on solid fuel, as well as for classic fireplaces and stoves. As additional advantages of coals of this grade, it should be noted that they:

• Easy to ignite, easy to use;
• Demonstrate the best quality/price ratio;
• They burn with a flame with long tongues, similar to burning wood;
• The process of burning one bookmark takes a lot of time and is accompanied by the release of large volumes of heat;
• For sustainable combustion, an additional blower is not required.

That is why long-flame coal is purchased not only by owners of private houses, but also by boiler houses of schools, administrations different levels, hospitals, etc.

The specified coal in stationary boiler plants has proven itself both in pulverized and in layer combustion. Therefore, almost all commercially available fractions of coal of the specified grade are in demand by the consumer: from "P" to "M".

Benefits of using coal in heating systems

Heating with coal in a private house has a number of significant advantages.

• Coal is mined in Russia and is not subject to such price fluctuations as liquid fuels.
• Its use does not require the presence of special gas pipelines, as for gas-fired heating.
• The cost of coal is lower than gaseous or liquid fuels.
• This type of fuel is easy to transport and convenient to store.
• Heating a house with coal is beneficial, as it is able to retain heat during combustion. Therefore, the air heated in the room does not cool for a long time.
• The high heat transfer of the specified fuel allows using its minimum volumes to maintain a comfortable temperature even in the most severe frosts.
• Coal is a problem-free fuel. In order for the heating to function properly, it is enough to initially install a chimney of the correct design and clean it in a timely manner.
• Storing the specified fuel is easier than the same firewood, for example. It is supplied to the consumer in bags. The only requirement for a place to store coal is that it must be dry.

The exact consumption of coal will always help you to do it at the place of its sale. And to roughly determine how much fuel you need for the heating season, the recommendations below will help. Despite the fact that this method is one of the simplest, it, at the same time, allows one to obtain fairly accurate results.

For a unit of measurement, we take a bucket with a capacity of 10 liters, which is a must-have in any private house (although officially the volume of coal is usually measured in tons). Accept average weight coal in one full bucket equal to 18 kg (you can check).

Practice shows that, when using a typical solid fuel boiler, for heating a house with an area of ​​​​about 200 sq.m. Depending on the season, there are the following coal consumption rates for heating:

• September-October - one bucket per day (i.e. 18 kg according to our assumption);
• November - February - ten buckets per day, which is equal to 180 kg;
• March-April - from one to two buckets per day. On average 22 - 24 kg.

Having calculated the total amount of coal required, we get that during the heating season, the consumption of coal for heating the house will be about 580 buckets. Multiplying this amount by 18, we get that for the season we need about 10440 kg.

If you consider such a calculation option to be archaic, and are inclined to solve everything from a scientific point of view, then we offer you the following option for preliminary determination of the required volumes of coal.

In order to receive 1 kW of energy, it is necessary to burn about 200 g of coal in a boiler.
For the whole season, while heating is required, it will be necessary to receive about 50,000 kW.

This implies. What you need for the season 0.2 x 50,000 = 10,000 kg. That is, the same 10 tons that we reached in the previous version.

Having resorted to this simple arithmetic, do not forget that each grade of coal has its own energy efficiency index. Therefore, having made a decision to purchase and choosing a seller, consult on the spot about what coal consumption for heating your house will be when buying coal of this brand.

Coal marking established for rational industrial use coal. Coals are divided into grades and technological groups; This subdivision is based on parameters that characterize the behavior of coals in the process of thermal action on them.

In addition to those indicated in the table, intermediate grades are distinguished in some basins:

• gas fatty (GZH)
• coke fatty (QOL)
• coke second (K2)
• weakly caking (SS).

Coals are divided into technological groups according to their caking capacity; to indicate the technological group, a number is added to the letter designation of the brand, indicating the lowest value of the thickness of the plastic layer in these coals, for example, G6, G17, KZh14, etc.

The abbreviation OK (OK1, OK2) can be at the end of the name of the coal grade, indicating the degree of oxidation.

Also, depending on the degree of enrichment, coals are divided into concentrates, intermediate products and sludge.

Concentrates are usually used in boiler houses and for generating electricity. Industrial products are usually used for the needs of metallurgy. Briquettes can be made from the sludge and retailed to the public for personal use.

Coal grades D, G and anthracites are used, as a rule, in boiler houses, because. they can burn without blowing.

Coal grades SS, OS, T are used to obtain electrical energy, because they have a high calorific value, but the combustion of this type of coal is associated with technological difficulties that are justified only if a large amount of coal is needed.
In ferrous metallurgy, grades G, Zh are usually used for the production of steel and cast iron.

Grade grades are a conditional division of coals according to their properties that satisfy certain needs. Therefore, there can be a significant number of them (varieties). The most universal is the classification according to genetic and technological parameters(GOST 25543-88. Brown, black and anthracite coals. Classification according to genetic and technological parameters). But it is designed for a general assessment of coals. To designate grades of coal intended for use in thermal power engineering, the following scheme is used Sort =<марка> + <размер-кусков>

For example, coal grade GR. This means that according to the brand composition - gas, and according to the grain composition - ordinary (piece size 0-200..300 mm). Moreover, in this case, the percentage of specific classes is not regulated. It can be coal consisting of 90% large fragments and 10% fines and vice versa. If the coal is designated TPK, then these are lean coals, sorted, with a size of pieces from 50 (40) to 200..300 mm. The content of small (less than 50 mm) debris should not exceed 15%.

The extraction and use of coal has long history. Over the past centuries, people have learned to use this fossil not only for heating homes and cooking.

With the development of industry and science, it began to be used in metallurgy and the chemical industry. At the same time, coal has not lost its position as a fuel for residential buildings, social facilities, and industrial enterprises.

The accumulated experience made it possible to understand that not all types of such fuel are the same, and therefore classification and labeling are needed in order to determine the appropriateness of use for specific purposes.

Classification

To determine the quality and consumer properties, coal is classified according to several characteristics, which depend on the degree of coalification:

• carbon content;
• ash content;
• content of volatile elements;
• the proportion of sulfur in the composition;
• humidity;
• heat of combustion.

According to the degree of coalification, which depends on the age of the fossil, there are the following types:

1. Brown, the youngest in age. It has a brown color, low strength, can be destroyed during storage. This variety is low in carbon, high in ash and volatile matter.
2. Stone. This fuel is most often black in color, may have a shine, the pieces are quite dense and durable. The amount of carbon can be up to 95%, the yield of volatile substances is relatively low, as well as the ash content. The variety is the most optimal for heating in terms of the ratio of characteristics and price. It has several subspecies: long-flame (D), gas (G), fatty (F), coke (K), skinny (T).
3. Anthracite is distinguished by a high degree of coalification, because it is considered the most ancient. The pieces have a deep black color and a characteristic anthracite sheen, as well as high strength. High-quality fuel, leading in all characteristics. It should be noted that its stocks are small and the cost exceeds the previous types.

In addition to classification by characteristics, a division by size of components (fractions) is used, which is also important for proper and effective use.

Brown coal

There are several pure fractions: plate (P, over 100 mm), large (K, 50–100 mm), walnut (O, 26–50 mm), small (M, 13–25 mm), seed (S, 6– 13 mm), chips (less than 6 mm).

Mixed fractions are possible: PC. KO, MO, etc.

In addition to high-quality, regulated according to GOST fraction sizes, ordinary coal (P) is used, the difference of which lies in the fact that it is delivered to the consumer directly from the extraction sites. The size of the pieces in this case can range from coal dust to pieces of 300 mm and percentage large and small pieces is not regulated.

Considering that ordinary coal goes on sale directly from the place of extraction, its price is lower than that of graded coal. The price does not include the cost of sorting by size. This makes such fuel more affordable. The price for popular consumer grades of long-flame and gas for ordinary coal starts from 1950 UAH per ton.

How to heat with fine and ordinary coal

To melt the stove quickly and safely, you should follow certain rules. For kindling, paper, small logs of firewood, preferably wood chips are used.

1. Before kindling, the stove is cleaned of ash.
2. Paper is laid out at the bottom of the furnace, on top of which wood chips are placed, and then logs of firewood. It is advisable to stack firewood in such a way that there is a gap for air to enter.
3. When the blower door is closed, paper is set on fire, when the wood chips and firewood light up, the firebox door closes and the blower door opens.
4. As the firewood burns out and the formation of smoldering charcoal, coal is poured on top of it thin layer, at this stage it is recommended to choose medium and large pieces.
5. Only after the complete combustion of large pieces, small fractions are added.
6. If the fuel contains more fine fraction, then it can be moistened a little, and the moistened coal dust can be moistened and formed into pieces, wrapped in newspaper.
7. It is important to remember that the use of any flammable liquid for ignition is very dangerous. This can cause fires and severe burns.

Undoubtedly, it is worth considering options for coal-fired boilers.

The main advantages of solid fuel boilers on coal:

• Charcoal burns longer than firewood, therefore, it requires less fuel loading;
• At a shallow angle, automatic loading is possible;
• There is a class of boilers that simultaneously work as stoves for cooking food;
• Most of the coal-fired boilers are universal and you can get by with other fuels in the absence of coal;
• Easier storage and takes up less space than firewood;
• Due to the peculiarities of heat transfer, this boiler does not immediately cool down, therefore it retains heat in the house for some time (even when it is turned off).

Marking of coal, grades of coal

There are many varieties of this fuel, the main types of coal are brown coal, hard coal and anthracites. In the marking of coal grades, they are indicated by the first letter: B (brown) or A (anthracite). Hard coal is marked more difficult: long-flame (D), coke (K), lean (T), fatty (F), gas (G). The second letter of the marking is the size of the coal. For example:

• slab, more than 10 cm (P);
• large, 5-10 cm (K);
• walnut, 2.5-5 cm (O);
• small, 0.13-0.25 cm (M);
• seed, 0.6-0.13 cm (C);
• pieces up to 0.6 cm (W);
• ordinary, different sizes (P).

Key quality indicators for coal

These three indicators will determine which coal is best for heating your home, your personal boiler brand and, in particular, for your convenience.

The first indicator is calorie content, it is also the heat of combustion. For grades, except for anthracite (8600 Kcal / kg), coking coals (8700 Kcal / kg) give a high combustion temperature, but they should not be used for household domestic boilers. Brown coals show the lowest temperature (4500 Kcal/kg). They are also usually not used for heating, since they are inefficient compared to other varieties (but in the absence of other varieties, brown ones are also heated).

The second indicator of quality is ash content. This is the percentage that does not burn during the heating process. The higher this percentage, the worse the quality of coal. Low-grade grades often contain more than half the ash, while high-grade grades often contain no more than a quarter. This indicator also tells you how often you will clean your boiler or stove. Anthracite has the best ash content, followed by weakly caking and gas.

Humidity is the third point for coal quality. Distinguish between the surface moisture of coal and the internal moisture. And if the surface can be removed by drying the coal, then the internal is found only in the combustion process. The higher the humidity, the less energy coal gives off for heating, and the more energy is spent on the evaporation of moisture during combustion. Sometimes it is advised to wet the coal so that the dust settles, but this is not always advisable.

What grade of coal is best for heating a house

Even if anthracite is immediately advised to you as the most profitable, “cleanest” in combustion (minimum consumption, maximum heat transfer, minimum slag and waste emissions into the atmosphere, only 1% sulfur and 10% ash residues, uniform combustion, etc.), don't rush to buy it right away. So what is the best coal for home heating? Everything is individual. Best - means "the best for your boiler". First of all, look at the marking of the boiler - it should indicate the types of coal that are suitable for your particular unit. Indeed, anthracite is the best heat transfer coal. But due to the characteristics of combustion (it is able to reach high temperatures, and only with them it gives up its full potential), you risk: either your boiler (the boiler may simply not withstand the temperature), or your wallet (anthracite simply will not give the desired efficiency) . There are boilers adapted for burning anthracites (their furnaces are designed for high temperatures), and there are those that are designed for the worst grades, but from them they get the most useful energy.

If there is no marking, or it does not suit you, try to purchase different varieties on a sample and conduct an experiment: fix the burning time, the heat of return, the amount of ash.

The main varieties and their suitability for heating:

• Anthracites - only for specialized boilers;
• Coke coals are dangerous in everyday life, they usually do not heat;
• Brown coals - low efficiency, they usually do not heat (unless the boiler brand has this);
• Gas coals are divided into two subspecies, only 1G group for this brand of coal is suitable for heating, group 2G is used in industry;
• Fat coals - valuable brands of coals, are used in the industry;
• Hard coal brand "long-flame" - the best choice after anthracite;
• Stone "DPK" (long-flame slab "fist") - the best grade of coal for conventional boilers;
• Stone "DO" - a lower indicator of efficiency, but it is easier to arrange fuel supply automation;
• Stone "DS" (long-flame seed) - similarly;
• Stone "TPKO" (skinny "walnut") - even less efficient, but cheap, used for heating small houses;
• Hard coal "SS" (low caking) and "TS" (lean low caking) are also cheap grades of coal used in industrial boilers and households.

Some experts advise to melt boilers with grades with lower efficiency, but easier to kindle, and then add grades of coal with higher efficiency to the furnace (for example, start heating with a long-flame seed, and continue with anthracite). In the case of a stove, it is even recommended to start with firewood (and continue, for example, with seeds).