With the transformation of China's economic structure and the vigorous development of renewable energy

coal-fired power plants usually run under low load condition for a long time. In order to reduce the influence of low load operation of coal-fired units on coal consumption of the units

the main operation technologies of improving thermal efficiency of the coal-fired boiler at low load are summarized in this study. The main technologies include reducing the oxygen content properly

reducing the fineness of pulverized coal properly

reducing the primary air speed properly

increasing the outlet temperature of coal pulverizer in direct pulverizing system

adopting the appropriate mode of air distribution

and running the lower coal mill or feeder and so on. The recommended value is presented according to the coal quality. At the same time

the influences of the exhaust oxygen content

flue gas temperature

carbon content of fly ash and carbon content of slag on boiler thermal efficiency are discussed for the boiler burning different coals.