What is the difference in calorific value between coke dust and coke?
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The coke powder obtained after screening and coke should be the same substance; then why do some companies report different calorific values? The calorific value of coke is 0.9714 kgce/kg, while that of coke powder is only 0.81 kgce/kg? Some people on the Internet say that the solid product of low-temperature coal carbonization is a loosely structured black semi-coke powder, with a low yield of gas and a high yield of tar ； The solid product of high-temperature coal carbonization is a densely structured silver-gray coke, with a high yield of gas and a low yield of tar; it seems to refer to the finished products obtained from burning different types of coal. But the calorific value of the coke powder and coke produced from the same type of coal should be the same, right?
My personal understanding is that it’s the same type of coal, but different processing methods are used. Low-temperature carbonization, commonly known as coal distillation, involves using this principle to extract volatile substances such as tar; the amount of gas produced in this process is very small； The remaining semi-coke is then gasified to produce gas; this is the main source of gas production. During the high-temperature carbonization of coal, some of the volatiles decompose as the temperature rises, which results in a lower tar yield.
In other words, the coke powder produced at low temperatures, and the coke produced at high temperatures? So, the calorific value of coke dust should be greater than that of coke, right?
As I understand it, the main component of coke dust and coke is still carbon, but there are differences in their minor components, which is why their calorific values vary