Is the moisture on an air-dried basis of coal the same as the internal moisture of coal?
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Is the moisture on an air-dried basis of coal the same as the internal moisture of coal? From the perspective of analysis methods for internal water and external water in coal, it seems that the moisture on an air-dry basis is the internal water of the coal; however, I’m not sure. I would appreciate your guidance! Also, when using ASPEN to simulate coal gasification, since coal is a non-conventional material, the water content must be entered as part of the coal’s property data. Does the water content required here refer to the total water in the coal, the external water, or the internal water? Thank you!
The percentage of moisture contained in the coal sample received and sent to the laboratory, expressed as a proportion of the mass of the received coal sample, is referred to as the total moisture content of the coal or the total moisture on a received basis, and is denoted by Mar. The coal sample is left in the air for a certain period of time, allowing the moisture contained in the coal to evaporate continuously into the atmosphere. When the vapor pressure of the water in the coal reaches equilibrium with the partial pressure of water vapor in the atmosphere, the percentage of moisture lost relative to the mass of the coal sample represents the extrinsic moisture on a received-base basis, denoted as Mf,ar. A coal sample that has lost its external moisture is called an air-dried coal sample. The percentage of the total free moisture mass remaining in the air-dried coal sample relative to the mass of the coal sample is referred to as the intrinsic moisture on an air-dried basis, and is denoted by Mad. Therefore, the air-dry basis moisture of coal is the internal moisture of coal. During ASPEN simulation, the water content in the coal’s working data must be entered as the total moisture on a received basis.