| 摘要 |
PROBLEM TO BE SOLVED: To obtain a desired degree of dryness and reduce a corrosion risk of a can body, while suppressing a height of an upper part header.SOLUTION: A boiler includes a can body 20 in a state where a water level inside a water tube 23 is lower than an upper end of the water tube 23 when a burner 30 is cut off, a water supply means 70, and a control means 100 for controlling an operation of the water supply means 70 responding to a water level of the can body 20, and is further equipped with a header water level detection means 60 for detecting a water level existing in an upper part header 24 and a precipitating water pipe 84. The control means 100 executes not only first control for controlling the operation of the water supply means 70 to cause the water level inside the can body to lower when the water level detected by the header water level detection means 60 reaches to the header setting water level but also second control for controlling the operation of the water supply means 70 to cause the water level inside the can body to raise when a drawdown of the water level inside the can body reaches a designated amount after the first control. |
