The influence of volatiles on gasification reactions
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Water-coal slurry gasification technology, 65 kg pressure, patent holder: GE. The currently used daily air-dry basis volatile fraction is 39; please discuss the impact of higher volatile fractions on gasification efficiency and the gasification reaction. In my opinion, a high volatile content leads to high reactivity of the coal, resulting in intense combustion reactions that reduce the gasification efficiency to some extent.
Volatile matter refers to the gaseous and vaporous products that are emitted when the organic substances in coal are heated to a certain temperature. It is an important indicator of the degree of coal metamorphism. The level of volatiles is a key factor affecting reaction activity; the higher the volatiles, the more favorable it is for the gasification reaction. However, a high volatile content has a significant impact on the storage of pulverized coal; over time, it can easily lead to spontaneous combustion and explosions of the coal dust. Volatile components do not participate in reactions during the gasification process; they evaporate first at high temperatures to contribute to combustion and provide heat for gasification ； After the volatiles escape, micropores are left in the coal powder particles, allowing oxygen or water vapor involved in the reaction to come into full contact with the coal powder, thereby increasing its reactivity. Hence, a higher content of volatiles is beneficial for the gasification reaction.
The gasification efficiency is the ratio of the chemical energy of the generated gas to the chemical energy of the coal fed in. As mentioned above, a high volatile content implies good reactivity; with all other conditions unchanged and the residence time constant, the carbon conversion rate is high, the carbon content in the fly ash is low, and the gasification efficiency is high