| 摘要 |
PROBLEM TO BE SOLVED: To prevent insufficient supply of steam, which has been caused by drastic lowering of steam pressure even in a case where steam is intermittently used. SOLUTION: A boiler 4 for stepwise control of a combustion rate in accordance with a steam pressure value, comprises a combustion device 2 for controlling the combustion rate stepwise, an operation control unit 7 which is set with high combustion for performing rated combustion and with low combustion for performing combustion at a rate smaller than the high combustion, and a pressure detector 1 for detecting steam pressure value. The control unit 7 is also set with a slow load pattern for switching combustion between high and low at a comparatively high steam pressure value, and with an abrupt load pattern for switching combustion between high and low at a comparatively low steam pressure value. The control unit 7 performs switching of these patterns according to the loading condition, thereby changing the steam pressure value for switching combustion between high and low.
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