【Weekly Topic】Discussion on the chemical reactivity of coal
Thread Content
“The chemical activity of coal is mainly related to factors such as the degree of coal metamorphism, ash composition, particle size, porosity, and specific surface area. Generally, as the degree of coalification increases, activity decreases. ”Please discuss and list the requirements for the activity value of raw coal in different gasification processes What are the main reasons for the reduced activity of raw coal when used to produce chemical coke?
1. In the field of coal chemistry, the “chemical activity” of coal is not generally referred to; instead, the chemical reactivity of coal is used to describe its chemical properties. 2. The reactivity of coal refers to its ability to undergo chemical reactions with various gaseous substances (such as carbon dioxide, oxygen, water vapor, etc.) under certain temperature conditions. Coal with high reactivity reacts more rapidly and efficiently during gasification and combustion processes. Especially in modern gasification technologies such as fluidized bed and gas flow bed systems, the reactivity of coal directly affects the speed of reaction within the gasifier, the degree of completion of the reaction, the amount of coal and oxygen consumed, as well as the composition of the syngas produced. Coal with high reactivity allows the gasifier to operate at lower temperatures while maintaining a relatively stable production capacity, thereby preventing ash sludging and disrupting the coal gasification process. In new fluidized combustion technologies, the reactivity of coal is also closely related to its burning rate. Therefore, reactivity is an important characteristic indicator for coal gasification and combustion. There are many methods for measuring coal reactivity, and in China, the commonly used method involves determining the ability of the coke formed after the dry distillation of coal at high temperatures (900°C) to reduce CO2; the degree of CO2 reduction is used as an indicator of coal’s chemical reactivity toward carbon dioxide. 3. The chemical reactivity of coal toward carbon dioxide decreases as its degree of metamorphism increases. Generally, lignite has the highest reactivity, followed by bituminous coal, subbituminous coal, thick-coal, coking coal, thin-coal, and lean coal, while anthracite has the lowest reactivity.
You’re too kind. I work in the coal chemical industry after all
The coal type determined from the coal seam exploration data is young bituminous coal, whereas the chemical reactivity data of this coal are indeed close to those of older anthracite. I would like to ask how this situation can be explained?