In proximate analysis, what does moisture content refer to?

• A. The amount of moisture produced during combustion.
• B. Water used in cooling towers.
• C. Water in the boiler feedwater.
• D. Water content within coal before combustion.

Answer: (D)

Moisture content in proximate analysis is the water that is already present in the coal before it is heated for testing. It is determined by drying a sample in a controlled oven (about 105°C) until its mass stops changing; the weight loss is reported as moisture content, usually as a percentage of the original sample. This moisture includes water on the surface and water physically bound within the coal's pores and structure that will be released as steam during heating. It does not refer to water used in the plant’s cooling systems or boiler feedwater, nor to water produced during combustion.