Heating with a coal boiler, characteristics of coal, the choice of boilers for coal

What fuel to choose

Coal is a chemical compound containing a number of hydrocarbons and impurities with low combustion rates. These substances are formed in the lower chamber of the boiler after combustion. These are slag and ash that must be regularly cleaned out of the blower. Moreover, in each of the types, depending on the geography and date of occurrence contains a certain level of Carboniferous. It is the age, the ratio of combustible and non-combustible components that determine the quality and brand of a solid fuel mineral.

There are several types:

1. The youngest of the subspecies is lingitis. It is a loose stone structure. Often crumbles and crumbles. Ineffective for heating houses. However, it is considered the cheapest, used for energy production in CHP plants.
2. Anthracite is a variety that warmed up most deeply when it was buried. It is a transitional form from coal to graphite. The amount of carbon reaches 95%. Most effective of all varieties.
3. Bituminous coal is the result of the transformation of bituminous masses. It is divided into several varieties depending on the carbon content, from 75-95%. Humidity reaches 12-15%.
4. The brown subspecies, unlike other varieties, is formed from peat and includes up to 70% of carbon. Has a characteristic white color. Washes can be used as fuel or raw material. Also includes a large number of volatile compounds.

Different varieties

Due to the minimum mass and significant carbon content, it is anthracite that has the maximum specific heat capacity. Indicators can reach 9 thousand Kcal / kg. Due to the lower content of combustible substances and higher humidity, coal has up to 5.5 thousand kilocalories per kilogram. Brown has an even lower indicator of 3 kcal / kg. Therefore, it is anthracite that is considered the best choice.

How to reduce coal consumption

An increase in the rate of coal consumption, after several years of boiler operation, is quite common. The increase in costs is primarily due to the clogging of the heat exchanger and chimney with soot. It is recommended to completely clean the chimney and internal components of the boiler, at least 2 times a year.

To reduce the consumption of coal, it is necessary to properly heat the boiler. To reduce the amount of soot, fill the fuel in layers - firewood-coal. This styling will provide maximum heat dissipation. The change in coal consumption occurs depending on the boiler efficiency. Consequently, the greater the efficiency, the lower the fuel consumption will be.

Another way to reduce coal consumption is to use only high-quality fuel. Cheap raw materials, brown coal, have a high percentage of undercooling, quickly clog the chimney and heat exchanger and, as a result, are more expensive than anthracite.

Fuel requirements

In order for the system to work properly, it is necessary to use high-quality fuel. Coal for long-burning boilers can be used in different ways. Usually, the most preferred types are indicated in the technical passport of the device.

Most often, brown coal, bituminous, coal, semi-anthracite and anthracite are used for heating private houses. The latter is considered to be of the highest quality. Models of European-made boilers are more sensitive to the composition and properties of the coal used. Domestic ones are unpretentious.

For models from any manufacturer, anthracite will be ideal. It has several advantages:

• when burning, it emits 80% more heat than natural gas;
• burns out almost completely and does not clog the boiler;
• emits less harmful fumes;
• has a high efficiency.

In addition, coal is sold in fractions of several sizes. Some manufacturers sell it in bulk, while others pack it in bags.The second option for a private house is considered more preferable, since in this form, the fuel does not contain dust, which worsens combustion and leads to rapid clogging of the boiler.

It should be noted that wet anthracite burns better than dried anthracite, so you should not be afraid of getting it wet during storage.

Preparing the stove for kindling

In case of infrequent use of the boiler, a visual inspection of the masonry is required before starting operation in order to exclude the presence of cracks. The penetration of carbon monoxide can be observed through the holes, which normally should leave the furnace through the chimney. If such gaps are found, it is imperative to eliminate them with the help of a heat-resistant sweep of clay and sand. Otherwise, during heating, the opening may widen with a consequent increase in the risk of rupture of the furnace or boiler.

When conducting an external examination, it is imperative to remove from the direct accessibility zone all objects that can ignite when hit by a spark. Then, you need to completely remove ash and slag. Then, wipe the walls of the firebox with a rag to prevent the spread of an unpleasant smell from the combustion products.

It is advisable to melt the coal boiler several times a day. The duration of one such process should not exceed 2 hours. Load small dry charcoal. If the fuel is wet, steam may form, which subsequently settles on the walls of the chimney, leading to a narrowing of the gap. As a result, the thrust will drop dramatically.

Pros and cons of wood-fired boilers for long burning fuel

Advantages:

• no need for frequent refueling - depending on the model chosen, you need to throw firewood into the combustion chamber from once every 3-4 hours and up to 12 hours;
• the possibility of using various types of fuel and their combination;
• the operation of the boiler is in most cases autonomous and does not require connection to other communications;
• relative cheapness of fuel.

Solid fuel boiler in a private house

Disadvantages:

• the cost is higher than classic boilers;
• due to the low calorific value of firewood, the efficiency is from 70 to 89%;
• there is no temperature regulation mechanism.

Another important drawback is the impossibility of heating equipment operation without human intervention.

Principles of operation of long-burning boilers

The principle of operation of a conventional solid fuel furnace is probably known to everyone. Firewood (coal, briquettes) is put into the combustion chamber, and from the lower blower chamber there is an air stream containing oxygen necessary for the combustion process. The combustion intensity is limited only by the volume of the incoming air and the area of ​​the outer surface of the fuel insert.

With ordinary firewood burning, the energy potential inherent in them is not used in full.

In fact, this is an ordinary fire, only enclosed in stone or metal walls, and requires constant replenishment of fuel. In this case, the combustion products are almost directly discharged into the chimney system, the labyrinths and turns of which only improve the heat transfer to the structural elements and, in a certain wall, lead to an increase in efficiency, but cannot in any way increase the overall energy efficiency of a particular type of fuel. The process of thermal decomposition of wood is very intense, short-lived, leaving a lot of waste and throwing unused opportunities into the atmosphere.

And these possibilities lie in the special properties of wood, which are due to its biochemical composition. During the heating process, this material does not simply oxidize to the state of coal with the release of ordinary carbon dioxide (CO2) and carbon monoxide (CO).High-temperature exposure always leads to the synthesis of volatile hydrocarbon compounds with a complex chemical formula, and they themselves are an excellent gaseous fuel, which is simply emitted into the atmosphere in conventional furnaces.

Burning wood with limited oxygen supply leads to the formation of pyrolysis gases, which are excellent fuel

The process of thermal decomposition of wood is called pyrolysis, respectively, the hot gaseous components released during this process are called pyrolysis gas. It is characteristic that the temperature of its combustion, and hence the heat transfer, is incomparably higher than that obtained with the usual burning of wood. At the same time, the processes of wood oxidation are so deep that after them there is practically no waste in the form of ash, and after the combustion of the gaseous component, mainly water vapor and carbon dioxide are emitted into the atmosphere.

This means that from the point of view of the technology of the most rational use of wood fuel, it is advisable to minimize the process of open combustion, to achieve the maximum release of pyrolysis gas, which will, in fact, be the main source of thermal energy during combustion. It is these principles that are incorporated into the design of long-burning boilers.

Coal saving methods

Coal consumption is high during the heating season, so homeowners want to reduce it. There are several ways to help you save a little:

1. Insulate windows and exclude cold air from entering through other cracks. Thanks to this, the room will be warm if the boiler is operating in a moderate mode.
2. Providing quality heating throughout your home also saves fuel by keeping the rooms at the optimum temperature.
3. It is allowed to re-sift combustion residues that are regularly removed from the ash pan. They often contain lumps of coal that can be reloaded into the furnace. However, it is necessary to carefully sort out the waste, since those that are unsuitable for combustion will worsen the process and reduce the efficiency of a new portion of fuel.
4. During combustion, it is necessary to control the air supply. If the draft is too strong, the charcoal burns out faster, so re-filling is required. At the same time, it does not get warmer in the house, since a significant part of the heat is lost due to increased traction.

1. Insulate windows and exclude cold air from entering through other cracks. Thanks to this, the room will be warm if the boiler is operating in a moderate mode.
2. Providing quality heating throughout your home also saves fuel by keeping the rooms at the optimum temperature.
3. It is allowed to re-sift combustion residues that are regularly removed from the ash pan. They often contain lumps of coal that can be reloaded into the furnace. However, it is necessary to carefully sort out the waste, since those that are unsuitable for combustion will worsen the process and reduce the efficiency of a new portion of fuel.
4. During combustion, it is necessary to control the air supply. If the draft is too strong, the coal burns out faster, so re-filling is required. At the same time, it does not get warmer in the house, since a significant part of the heat is lost due to increased traction.

Some even remove the valve, mistakenly assuming that this will help warm up the room faster. As a result, the coal burns out instantly, but there is no heat in the house. If none of the methods have helped to reduce the amount of fuel used and the rooms are still cool, it is recommended to re-check all windows and doors, and also to exclude the possibility of cold air entering through the holes in the floors. Quite often, they are invisible under the skirting boards and do not allow achieving optimal temperature conditions.

How to use solid fuel plants correctly?

The principle of operation of a solid fuel boiler is known, and the issue has been resolved with the choice of a type of coal. It remains to learn how to properly heat the stove. There are several simple rules that everyone who chooses the described installations for organizing the heating of a country house should learn.

Let's dwell on all these points in more detail.

Preparing the stove for kindling

If the stove in a country house is used from time to time, before starting its operation, for safety reasons, it is necessary to exclude the presence of cracks inside the masonry.

Why are they dangerous? Through them, combustion products and carbon monoxide can penetrate into the room, which must be discharged outside with the help of a draft. If such a defect is found, it must be eliminated before kindling by covering the cracks with a mixture of clay and sand. Otherwise, when heated, cracks can increase in size even more. And this will lead to dangerous situations.

Inspecting the oven from the outside, remove flammable objects away from it and clean it inside. We scoop out ash and slag with a spatula, freeing up the inner compartment. It is advisable to wipe the inner walls of the furnace with a dry cloth. If this is not done, then during the kindling, the dust will begin to burn, filling the room with an unpleasant odor.

It is necessary to heat a coal stove several times a day. The duration of one firebox should not exceed two hours. It is better to use well-dried medium fraction coal for loading.

To ignite coal, do not use household waste, as well as flammable liquids - gasoline or kerosene. Do not leave the stove unattended during combustion. This rule must be observed especially strictly if there are small children or animals in the house.

How to properly melt coal?

It is necessary to heat the stove as follows:

• First, we put sheets of newspaper or any other dry paper on the bottom of the firebox. On top of it we place a layer of small wood chips. And on them we stack small firewood, for example, birch logs. In order for them to flare up faster, they must be folded in the form of a well or a small hut.
• We set fire to the paper. We close the oven door, and open the blower. With it, it is easy to control the intensity of fuel combustion. The stronger the air flow, the faster the firewood burns out.
• After the wood is completely burned out, and only a pile of smoldering ash remains, you need to lay a 15-centimeter layer of fine coal directly on it.

Which coal to choose for the furnace?

What is coal? It is a vegetable product that contains carbon and non-combustible impurities. It is they who form ash and slag-like substances after burning. The ratio of the two components is different everywhere. It is this, as well as the "age" of the fossil fuel, that determines the coal grade. Experts distinguish between several varieties.

The "youngest" type of coal is lingitis. It has a rather loose structure. If you pick up a lump of lingitis, it quickly crumbles and loses its shape. Such coal is most often used in thermal power plants, but lingitis is not suitable for heating a house.

In addition to lingite, lignite, bituminous coal, anthracite are also mined - the most ancient carbon deposits. All varieties have different moisture levels. In brown coal, for example, the moisture content is 50%, in anthracite its threshold does not exceed 7%. Therefore, anthracite has the highest specific heat. Its indicators are 9 thousand kcal / kg. Coal has a lower indicator - 5.5 kcal / kg. In the brown variety, the specific heat is only 3 kcal / kg. Considering all this, it is easy to understand what type of fuel to purchase for heating a house.

Coal boiler firing technology - how to heat properly

The operation of coal-fired boilers is carried out according to the following technology:

1. First of all, dry starting material is put into the firebox - rolled newspaper or paper. A small layer of wood chips is placed on top, and even higher - small firewood (for example, birch). It is best to lay out firewood in a hut or in the form of a well so that they burn better.
2. The paper placed in the firebox is ignited. The boiler door closes, and the blower opens. With the help of a blower, you can adjust the intensity of combustion - an increase in the supply of oxygen directly affects the speed of burning firewood.
3. A layer of small coal is laid on top of completely burnt wood, transformed into smoldering ash. The thickness of the carbon layer is about 15 cm. Each time the door is opened, the blower must be completely closed.
4. After the first layer of coal burns out, another layer is laid out directly on it, but a coarse fraction is already used for it. The thickness of the main fuel layer should be about 60 cm. Before laying a new batch of fuel, it is better to stir up the previous one a little in order to increase the intensity of air movement and prevent the coal from caking into one large piece.
5. Low-quality fuel can coke during combustion. To avoid this phenomenon, it is advisable to dilute the main coal layer with small layers of firewood - this will allow the boiler to warm up normally and provide maximum heat transfer. The presence of a layer, among other things, will also significantly simplify the process of cleaning the boiler after fuel combustion.
6. Proper firing up of the boiler assumes that natural circulation is used to burn paper and chips, which is achieved with an open ash pan. Due to this effect, the chimney will warm up, and the draft will increase gradually, and at a certain moment it will only be necessary to close the ash pan and turn on the fan.

Features of models with support for DHW

There are boilers that already in the basic configuration have a boiler installation that allows you to heat water as the fuel burns. Other models allow the possibility of optional additions with water tanks, but this solution will be more expensive and less profitable in terms of reliability.

Therefore, plan the DHW support option in advance. Its basis, as already noted, is a boiler installation, that is, a container for heating water, which is usually located next to the equipment. Its volume can vary from 50 to 200 liters when it comes to home use of a solid fuel boiler. Coal in this case will act as the basic energy resource for both heat supply and hot water supply. As the water heats up and flows out, the controls will open or close the isolation valve. The liquid resource can be used both for heating needs and for maintaining a bathroom with a kitchen. For each of these cases, its own configuration of water supply and heating circuits is provided.

Types of solid fuel boilers

traditional fuels,

1. The first type of boiler is called cast iron. It is designed to burn fuels such as coal and wood. Despite all its positive aspects, it is still dependent on humans and energy supply. Firewood in such a boiler burns, as a rule, no more than 5 hours, which means that fuel must be constantly added. Currently, domestic and foreign manufacturers produce such boilers, some of them are called KChM and Solida.
2. The second type differs in many respects from the first and is called pyrolysis heating boilers. There are two combustion chambers, one of which burns fuel immersed in the boiler, and the second burns out synthesis gas. The main fuel is wood.It surpasses a cast-iron boiler with a burning time, here it is 10 hours. One of the most successful boilers of this type is called Dakon, made in the Czech Republic.
3. Pellet boilers, the name comes from the word pellets (granulated wood). It is she who needs to heat the room with the help of such boilers. It has a convenient additional advantage - it independently refills the required amount of fuel using a screw and ignites it. Burning time in this case depends on the boiler model and the capacity of its hopper. But there is also a significant drawback - it is impossible to burn anything except wood pellets in such a boiler.
4. The most modern and popular type is long-burning boilers. Firewood, sawdust, coal, peat can be used as fuel. They surpass their counterparts in combustion time, with such a boiler no human intervention is needed for 2 days or more thanks to the newest top-down combustion system, this allows the fuel not to burn, but to smolder for a long time.

Solid fuel boilers are a good alternative to gas. If you live in a country house or your street is not supplied with gas, a long burning boiler on charcoal wood and other fuels will perfectly heat a room of any size.

How to choose a solid fuel boiler

When choosing a boiler, you should pay attention to the following criteria:

• boiler design;
• principle of operation;
• power;
• type of raw materials used;

First of all, you should pay special attention to power. This is one of the most important criteria and it is on it that the operation of the boiler depends, since not every model can cope with a too large heating system at home

It is necessary to clarify the power of the boiler with a specialist, he will compare such criteria as the area of ​​the house, the climatic region and even the height of the ceilings. The approximate required power can be calculated independently based on the following rule: 1 kW of power is needed for 10 square meters.

An error in the choice of boiler power can have a bad effect on the quality of heating. With a lower degree of heating, the room will be cold, and with a higher degree of heating, the equipment may fail.

Boiler installation location

separate room. separate boiler room

Three important rules when choosing a boiler installation site:

Ventilated area If supplemental gas is used as fuel, a small leak may occur. If the installation is done correctly, there is no need to be afraid of leaks, but in the case of their long-term accumulation, the likelihood of poisoning is high.
Deep cellar Not the easiest option for installing a boiler, but still, if the house has the ability to install it at a depth of 2 - 3 meters from the heating radiator, it will be ideal

Thanks to such an installation, additional circulation is not needed, you can not use circulation pumps, if the installation option is only in the house, circulation is mandatory, if it is absent or improperly installed, carbon monoxide leakage is possible, it is impossible to determine its presence in a room without special devices, and poisoning with it easily.
Chimney It is important to provide the required draft. In case of an error in these calculations, it is possible to reduce the power of the boiler and the ingress of combustion products into the room.

A specialist should install the chimney, since it is easy to make a mistake in this difficult matter and lose heat.

Subject to all the rules, a solid fuel boiler will work properly for many years.

What kind of coal is better to heat the boiler

The manufacturer initially conducts heat engineering calculations and adapts the design of the combustion chamber and heat exchanger to a specific type of fuel. Therefore, in order to increase the efficiency of a domestic boiler, it is enough to use coal of the brand and fraction specified in the operating instructions.

What brand of coal to heat

The composition of coal includes carbon and non-combustible impurities that form ash and slag after combustion. The ratio between carbon and impurities depends on the selected fuel grade. Coal has (depending on the brand) different degrees of moisture, loose or hard structure, age of formation.

In order to efficiently heat a coal boiler, it is necessary to understand well what characteristics distinguish one or another type of fuel:

• Lingit - this type of fuel has a loose structure and a high percentage of ash. Lingit is used in industrial power plants. This type of fuel is not suitable for heating a house.

Bituminous coal - has a heating value of 5500 kcal / kg. The percentage of carbon is not less than 75%. Ash content from 2 to 4%. Most domestic boilers of the classical type are fired with coal. For gas generator equipment, it is not suitable due to the humidity above 20%.

Brown coal - calorific value is only 3000 kcal / hour. When incinerated, large amounts of ash and coking matter are formed. Humidity is at 50%. Brown coal is not recommended for heating household boilers, due to the rapid clogging of the chimney and heat exchanger.

Anthracite - the humidity threshold is within 7%. It has high specific heat indices, equal to 9000 kcal / hour. The share of ash carried away by gases from the coal boiler is not more than 7%. Anthracite, manufacturers of heating equipment, recommend heating gas-generating boilers. Coal is divided into several grades by size: fist, nut, seed.

Is it possible to heat with coal briquettes

Coal briquettes are made by pressing fine fractions (dust). As a binder, special organic or mineral compounds are used. The latter greatly increase the ash content of the fuel, but are cheaper. The most popular are coal briquettes, in which coal tar acts as a binder.

Pressing coal heating has the following advantages:

1. Easy to lay in the combustion chamber.
2. Good flammability.
3. High calorific value, identical to anthracite.
4. Ease of storage and transportation - briquettes have the correct geometric shape, so they are easier to store and take up less space.

The only drawback of pressed coal is the high cost, which exceeds the price of lump raw materials by about a third. An advantage is the ability to heat the boiler with coal, without contamination with combustion products.

How to heat with coal dust

The safest and most effective method of burning dust is considered to be a method using a special burner device.

Is it possible to heat with charcoal

With all these advantages, charcoal has one serious drawback. The cost of a kilogram of purchased charcoal will cost almost 2 times more than coal. It is possible to somewhat reduce the cost of raw materials by setting up its independent production. To obtain 1 ton of charcoal, you will need to burn about 10 m³ of wood.

Which coal to choose for the furnace?

The fuel is selected in accordance with the recommendations of the boiler manufacturer.

The fact is that there are several types of coal, and they differ significantly in characteristics:

• brown coal. The most common and of the least quality: burns quickly, smokes and emits an unpleasant odor, generates a lot of waste: structure - earthy, color - brown or black, heat capacity: 16-22 MJ / kg, cost: 3.5-4.5 thousand rubles ... per ton;
• coal. Black with metallic or resin sheen. Good quality and at the same time affordable cost. There are several varieties, the most common is long-flame coal: heat capacity: 26-32 MJ / kg, cost: 5.5-7 thousand rubles. per ton;
• anthracite.Gray-black with a luster of glass or metal. The highest quality and most expensive: heat capacity: 32-36 MJ / kg, cost: 8-10 thousand rubles. per ton.

The use of the "wrong" coal leads to cost overruns or damage to the heater. So, when anthracite burns in the optimal mode, the temperature in the furnace reaches 2200-23000C. When loading such fuel into a conventional steel boiler, designed for brown coal, it will quickly burn out.

Or you will have to "hold back" the combustion by cutting off the air supply, due to which the efficiency of anthracite will drop sharply and the cost of purchasing this expensive coal will turn out to be unjustified.

Anthracite

Another example: long-flame coal, due to high humidity, is unsuitable for a pyrolysis boiler - condensate is abundantly formed in the chimney, which mixes with the combustion products and turns from this into a viscous resinous substance. These heaters require gas-fired coal.

There are toxic types of coal containing more than 2% sulfur. It is strictly forbidden to use them as fuel for furnaces and boilers: during combustion, sulfur oxide (sulfur dioxide) is formed, poisoning the air and destroying metal parts.

How to properly melt

The algorithm of actions looks like this:

1. It is required to arrange sheets of dry paper at the bottom of the firebox. Then, a small layer of wood chips, logs, preferably fruit varieties. To accelerate the fire, it is required to arrange them in a pyramid.
2. Set fire to paper. Then close the door, but leave the ventilation hole open. Due to which you can adjust the speed of combustion of firewood. Moreover, depending on the amount of oxygen, the fuel will burn faster or slower.
3. After the firewood has completely burned out, you need to place a layer of small coal, up to 15 cm, on the resulting pile of ash.
4. When it is sufficiently burned, you can pour a larger mineral on top in the form of a pillow. The height can reach 60 cm. Before that, be sure to move the hot stones apart so that the coal does not bake.

If you use fuel of insufficient quality, then its coking can be observed. Therefore, if you are not sure about the quality of the purchased raw material, put it in the form of a sandwich, stirring it with wood. Several layers of logs, successively mixed with stone, make it possible to sufficiently warm up the installation and give off heat to the premises.