Conditions to be Considered when Purchasing Coal
Coal is a very important resource for the industries of all countries. It has been used for many years to meet the heating needs of people, as well as to supply the energy production and industry needs. Features such as being widespread in the world, ease of transportation, convenience of storage facilities and low cost compared to other fossil fuels make coal the most preferred energy source.,
Coal, which continues to be widely used today, also has a large economic volume. Turkey is very rich in terms of coal mines. The ratio of both producers and consumers is high. At this point, the correct determination of the economic value and energy value of the coal while the sales transactions are carried out; It is very effective in terms of buyer, seller, and coal efficiency. The conditions to be considered while purchasing coal are stated and explained below.
1. Calorific Value
Coal is one of the most important fuels used for obtaining energy. Although its use for heating purposes has decreased today, coal used as fuel in steam boilers is also preferred to generate electricity. For efficient use, the quality and caloric value of coal must be known. Coals which have high calorific value are classified as high quality. It is possible to save on the amount of coal to be used by burning coal with higher quality. However, the coal to be preferred varies according to the characteristics of the boilers used. The calorific value of coal varies according to how many hours the boiler will be operated, for what purpose it will be used, boiler volume and pressure ratios, and how many years it has been in operation. The use of very high calorific value coal in each boiler does not mean that the energy value obtained will be high. At this point, coal fuel with the calorific value suitable for the specified characteristics of the boilers should be selected.
2. Moisture Content
Moisture is the amount of water contained in the coal content. Moisture reduces the calorific value of coal because it is non-flammable. High moisture content of coal cause low efficient energy to be obtained when burned. Because some of the energy released of the combustion process is spent for the evaporation of the moisture in the coal content. At this point, by knowing the moisture value of the purchased coal, it can be calculated how much energy will be obtained when dry coal (moisture-free coal) is burned. In this way, the amount of energy to be obtained from the preferred coal can be increased, and at the same time, profit can be obtained economically. By choosing coal with low moisture value, more energy can be obtained with less amount of coal in the boilers operated.
3. Ash Amount
Ash is a non-combustible inorganic substance contained in coal. When coal is burned, the remaining ash reduces the calorific value of the coal. The reason for this is that some of the energy released when the coal is burned is spent for the combustion of the non-combustible material ash. If coal, whose ash amount analysis has been carried out and whose value is known, is preferred, the amount of energy obtained can be increased and an economic profit can be obtained. In addition, the excess ash of the coal used causes the stove, boiler, and chimneys to be polluted and clogged more frequently. With the use of coals containing high ash, the number of particles discharged from the chimney will also increase, causing serious air pollution.
4. Sulfur Content
The sulfur contained in the coal creates sulfur dioxide during the combustion process. The amount of sulfur in the coal content affects the gross calorific value (upper calorific value) of the coal. The increase in the amount of sulfur in its content reduces the caloric value. The reason for this is that some of the heat generated by the combustion of coal is also spent on the formation of sulfur dioxide. In addition to its negative effect on energy value, sulfur dioxide causes serious air pollution and acid rain. Increasing the sulfur dioxide concentration in the air by burning coal is very harmful to human health and plant.
5. Volatile Matter Content
Volatile matter is all volatile substances in the coal content. The high or low amount of volatile matter makes it possible to decide whether the preferred coal is bottom-fired or top-fired. Depending on the amount of volatile matter used, it should be determined which type of boiler or stove will be used. For example, coals with low volatile matter content should be preferred in stoves, while coals with high volatile matter content should be preferred in conventional heating boilers. Coals with high volatile content can burn with a long flame and the flame formed during combustion can give off heat for a longer time.
6. Swelling Index
The swelling index is used to determine the agglomeration properties of coals during combustion. Coals showing agglomeration feature cannot perform an efficient combustion process. Coals with a high swelling index are suitable for coking. When coals with high swelling index are preferred for heating purposes, it causes clogging of the chimneys. When such coals are burned, chimney cleaning should be done frequently. However, the use of these coals for heating is not recommended.
7. Size of Coal
The coal size to be preferred should be chosen by paying attention to which type of boiler or stove it will be used in. It is not possible to burn very large pieces of coal in a balanced way. Since they cannot be processed correctly, the amount of sulfur, ash and moisture in their content is high and they provide low efficiency combustion. Domestic and imported coals should generally be in the range of 18-150 mm.
8. Responsible Person
Responsible person for purchasing coal must be familiar with the relevant coal standards. Knowing the definitions of moisture, ash, volatile matter, elemental analysis of coal and calorific value in coal is important for increasing efficiency in the use of coal. In addition, the license of the institution from which the coal will be purchased gives confidence in the quality control of the coal and provides economic gain. Institutions and individuals selling coal in the open should be inspected. The sale and use of open coal causes great harm to the environment. Care should be taken against possible damage. Persons and persons should be supervised for problems that may arise during the burning process. The sale and use of open coal causes great harm to the environment. Care should be taken against possible damage. If you are prepared for problems that may arise during the incineration process, financial losses can be reduced and damages to the environment and human health can be prevented.