Abstract: The necessary of improving the reliability of thermal control equipments for medium-speed mill was emphasized according to the analysis of its function and position in 600 MW supercritical units. By researching the influence factors of their installation and commissioning as well as the working condition in normal operation, the author made it clearly that the key points were to raise the reliability of slag extraction valves and quality of the mill inlet wind. Therefore some practical measures in technology and management have been put forward, and how to resolve those two difficult problems in 600MW supercritical unit in Fujian Huadian Kemen Power plant has been introduced in detail.

Key words: medium-speed coal mill, thermal control equipment, reliability, inlet wind quality of mill, slag extraction valve