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Various gasification furnaces have certain requirements for coal types, and their adaptability to different coal types varies depending on the reaction mechanism. A gasifier with good adaptability to different coal types refers only to one that has better adaptability to various coal types compared to other gasifiers, and specifically means it can be designed to handle different types of coal. However, for any well-designed gasifier, its adaptability to different coal types is very limited; in such cases, strict testing must be conducted when changing the type of coal. The following are the types of coal and particle sizes suitable for use in common gasification furnaces. Gasification furnace types: moving bed, fluidized bed, gas-flow bed, molten-bed. Particle size of raw coal in mm: 40–5, 3–0.5, less than 0.1, less than 3.0. Suitable coal types: lignite, sub-bituminous coal, bituminous coal; lignite, sub-bituminous coal; all coal types; all coal types. Although lignite can also be gasified in a moving bed, it must first be converted into pellets or rods before being fed into the gasification furnace. Inside the gasifier, coal balls or coal sticks tend to break easily due to drying, which can have a significant impact on the flow of air through the bed. Furthermore, lignite generally has a lower ash fusion point, which also causes caking in moving-bed gasifiers. On the contrary. Fluidized bed and gas-flow bed gasifiers are very suitable for the gasification of lignite gas. The preferred coal type for fluidized bed gasifiers is subbituminous coal, followed by bituminous coal. When gasifying coal that tends to sinter, it is necessary to install mixing impellers in the moving bed to prevent sintering from occurring; however, this increases the dust content in the gas significantly (typically 2% of the coal gets carried away). Gas flow bed and fluidized bed gasifiers can handle a wide range of coal types. Higher gasification temperatures and finer particle sizes enable the gasification reaction to be completed in a very short time, leaving almost no time for coal particles to agglomerate. A key aspect of current research on gasification technology is the optimization of coal particle size to improve the adaptability of the gasification process to different types of coal. Many power plant owners purchase coal from coal markets around the world. For gasification technology to be widely adopted, it must be insensitive to the type of coal, being able to function with a wide range of coal varieties.