Coal is a complex mixture containing organic and inorganic components, and its molecular structure is very complex. Water is an important component of coal. In the actual combustion process, water can't give off heat, on the contrary, water gasification will absorb some heat, so the existence of water will affect the combustion, calorific value, ashing and burnout of coal.

Extended data:

Classification of moisture:

1, total moisture

When the coal sample is dried at 102- 105℃, the lost mass is total moisture. Or directly into moisture. The moisture content of various coals varies greatly, ranging from about 2% to 50~60% at most. Generally speaking, with the increase of geological age, the moisture content of coal gradually decreases, which is also related to factors such as mining mode, transportation and storage conditions.

2. External moisture

Fuel will lose moisture due to natural drying, which is external moisture or surface moisture (Boiler Principle edited by Fan Congzhen of Southeast University).

3. Internal humidity

When coal is placed in a saturated space full of steam to reach equilibrium, this moisture is called internal moisture or inherent moisture. If the inherent moisture cannot be removed by air drying, it must be heated to 102~ 105℃ to remove it. The sum of internal moisture and external moisture is the total moisture.

Step 4 analyze moisture

When testing and analyzing coal, it should be dried naturally in the laboratory at the specified temperature and relative humidity, and the internal moisture contained in the dried coal sample becomes analytical moisture.

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