| 摘要 |
PROBLEM TO BE SOLVED: To prevent a steam pressure controller for boiler from making such dangerous combustion control that the steam pressure of a boiler abnormally rises even when abnormality occurs in a pressure switch. SOLUTION: The boiler 1 is provided with a pressure type combustion controller 9 which performs combustion control based on the output of the pressure switch 4 and a temperature type combustion controller 10 which performs combustion control based on the output value of a steam temperature sensor 5 so that combustion control may be performed based on either the pressure or temperature of steam. The steam temperature at a set pressure when the pressure switch 4 is normal is stored as an initial value and the steam temperature at the set pressure of the switch 4 at the present time is detected as the present value. Then the present value is compared with the initial value and, when the former is higher than the latter by a prescribed value or more, the combustion control is performed by means of the temperature type combustion controller 10. When the present value is lower than the initial value by a prescribed value or more, the combustion control is performed by means of the pressure type combustion controller 9.
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