| 摘要 |
PROBLEM TO BE SOLVED: To obtain a desired degree of dryness, prevent water pipe overheating and furthermore reduce the risk of corrosion of a can body.SOLUTION: A separatorless boiler includes: a downcast pipe 84 that interconnects the bottom in an upper header 24 and a lower header 22; and a control means 70 that performs a first control that controls a water supply means 60 in a manner so that the water level in the can body decreases when the water level detected by an external water level detection means 50 exceeds a first set water level, and a second control that controls the water supply means 60 in a manner so that the water level in the can body rises when the detected water level becomes no greater than a second set water level that is lower than the first set water level. The first set water level is set to the water level of the limit degree of dryness, the height of the upper header is set in a manner so that the degree of dryness of the water vapor flowing out from the upper header by means of the first control is at least the set degree of dryness, and the second set water level is set to a water level that is at least the overheating threshold water level and that causes the circulation ratio of can water resulting from the downcast pipe 84 to be at least a set value. |
