During the wet-dry state switch process of once-through boilers

operation condition of start-up thermal system is extremely complicated.Manual control can easily impose a disturbance on the system

especially inappropriate control of water-coal ratio can cause frequent wet-dry state switch and severe fluctuation of unit parameters

affecting the unit's normal operation.Through analysis on wet-dry state switch process of once-through boilers

an automatic wet-dry state switch scheme realized by controlling the fuel amount and feedwater quantity was proposed and applied in 2×600MW units once-through boilers of a power plant

helping this plant realizing full automation control of the dry-wet state switch.