Types of coal
The quality of coal and the scope of its application depend on the composition and structure. The "category" that is assigned to coals provides for the specific heat of combustion, the percentage of moisture and the properties of impurities.
Lignite
Lignite has a loose structure and is characterized by a high percentage of ash formation. The raw materials are in demand on an industrial scale. It is bought by factories, plants, power plants. Despite its narrow specialization, this type of coal is also suitable for “domestic” use as fuel.
The heat of combustion of lignite is 2800 kcal per kilogram.
Brown coal
Brown coal occupies an intermediate position between lignite and hard coal. When incinerated, forms a large amount of ash and coking derivatives. With a humidity level of 50%, brown coal is used by industrial boiler houses and chemical industries. This material is not very suitable for kindling household stoves and boilers. Regular use of brown coal leads to clogging of the chimney structure and heat exchanger.
The heat of combustion of brown coal is 5000 kcal per kilogram.
Coal
Bituminous coal is considered to be a quality product, which in its properties is close to anthracite. Coal contains 70% carbon and 3% ash. Due to the low moisture content (up to 20%), raw materials are not used by devices for converting fuel into gas. For the same reason, coal is well suited for sauna stoves.
Raw materials are divided into two categories depending on the combustion method:
- long flame: immersed in household heating structures, creating a high flame and long burning. Does not need additional airflow. To kindle the raw materials, you will need firewood or wood particles;
- slightly baked: intended for heating houses, steam rooms and industrial buildings. The advantages of raw materials include increased thermal conductivity and lack of sinterability. The combustion is not accompanied by smoke.
The heat of combustion of coal is 5000 - 5700 kcal per kilogram.
Anthracite
Anthracite has the status of the best fuel. It can be distinguished by its dense texture and black color. The record low humidity level (~ 7%) leads to a decrease in ash volume. Ash leaves the heating structure together with gases. Anthracites are found in different sizes: small specimens are comparable in size to seeds, and large ones are comparable to tennis balls.
The heat of combustion of anthracite is 7000 - 9000 kcal per kilogram.
Which type of coal burns longer?
Long-flame coal is often used to heat private homes. This raw material is universal and can be combined with all solid fuel boilers, stoves or fireplaces. The advantages of long-flame coal include:
- long burning period;
- fast combustion;
- thermal conductivity;
- ease of use.
It takes 4-6 hours to burn one fuel tab. The combustion process releases a large amount of heat energy. It will not be difficult to recognize long-flame coal when purchasing - the raw material is marked with the letter "D".