Coal commodity activity after China’s successful recovery from the Coronavirus outbreak began to provide a glimmer of hope. The reason, the price of coal again rose slowly but surely. Coal price is determined by a number of external and internal factors and one of the internal factors is the quality of the coal itself. There are a number of common techniques to find out how good the quality of coal is. Here’s a review.
Coal Size
Size becomes a technique that can be done by making observations on coal. The parameters are from the size of the fine grain range of coal, commonly called dust coal or pulverised coal, as well as seen from coarse grains or commonly called lump coal. For fine grain size is a maximum of 3 millimeters and for coarse granules of 50 millimeters.
Moisture Content
Coal moisture is divided into two types namely, free moisture and inherent moisture which if summed will be the total moisture. This will greatly affect the use of primary air needed. If coal has a high enough humidity, then it takes a lot of primary air to dry it.
Deterioration Rate
In Latin, the Hardgrove Grindability Index is very influential on the work of pulverisers. If the value is low, then the capacity should adjust the value by operating low. It is set to determine the appropriate level of smoothness.
Calorie Content
Caloric content or Calorific Value can be used as a benchmark of coal quality because it is very influential on coal processing equipment. The high caloric content used at the time of processing, will make the flow of coal lower, and then required adjustments to the coal feeder. Meanwhile, the operating ratio on the pulveriser will also be low, depending on the moisture content and the level of coal deterioration.
Sulfur Content
In coal sulfur content is divided into three types namely, organic sulfur, sulfur sulfate and pyritic sulfur. However, in general, the size of sulfur content in coal is measured in Total Sulfur units. Sulfur content in coal, will later affect the corrosion level of air heating elements.
Ash Content
During the combustion process, this ash content will be carried through the combustion chamber and the conversion part in the form of flying ash is known to amount to 80 percent, while the base ash is 20 percent. In general, this ash content will affect the level of wear on the equipment, corrosion and impurities.
Carbon Content
The amount of carbon content in coal can be measured by the formula of reducing the amount of 100 with moisture content, ash content and the content of existing flying substances. Later, carbon levels and flying substances will be used to determine the required fuel ratio.
Flying Substances
Combustion and fire intensity are used, depending heavily on the content of flying substances or Volatile Meters. The amount is measured based on the ratio between carbon content and flying substances which is then named fuel ratio. To determine the above levels in coal, of course it takes analysis in the laboratory, for then the processing process is measured to produce coal with high quality.