PURPOSE: To evaluate and select coal and to prevent clogging of piping with pulverized coal by drying powdered coal, granulating, sifting the granulated coal, measuring a sieve residual ratio and comparing the measured value with a standard value.

CONSTITUTION: Coal is powdered, dried until ultimate water content value in practical drying facilities (e.g. by air flow drying at 200°C for 2 seconds) is attained, granulated, a granulated material is sifted by a sieve (e.g. 1 mm mesh) for a fixed time (e.g. 30 seconds) and then sieve residual ratio is measured. The measured value is compared with a standard value set based on correlation between sieve residual ratio and frequency of piping clogging to evaluate coal for producing pulverized coal.