| 摘要 |
<p>PURPOSE:To prevent the abnormal stop of combustion due to the momentary lowering of the water level of a boiler by a method wherein a lower limit water level detector is provided to elongate a time until stopping combustion markedly when the capacity of a feed water pump becomes lower than the rated capacity thereof and provide a set time for stopping the combustion. CONSTITUTION:A small boiler 1 is operated, then, a feed water pump 7 and a combustion device 9 are operated whereby stem is generated. When the feed water pump 7 is operated, a water level in the boiler is ascended and an upper limit water level detector 3 outputs a water level detecting signal, the feed water pump 7 is stopped by the operation of a controller 5. The controller 5 outputs a feed water operating signal when a set time T1 has elapsed after receiving a water level non-detecting signal whereby the pump 7 is operated and the water level of the boiler is maintained within a predetermined range. However, when the water level of the boiler is lowered and a lower limit water level detector outputs the water level non-detecting signal due to unforeseen accident, such as the failure of a non-return valve 8, the mistaken operation of a blow valve 10, the deterioration of the capacity of the feed water pump 7 or the like, the controller 5 outputs a combustion stopping signal to stop the combustion device 9 whereby the overheating of the main body of the boiler may be prevented.</p> |
