Patent ID: 8677947

Claim:
A boiler system comprising: a boiler including a boiler body configured to carry out combustion, a discharge unit configured to discharge combustion gas generated in the boiler body, a discharge passage configured to allow the boiler body and the discharge unit to communicate with each other, and allow the combustion gas to flow therethrough, the discharge passage at least partly having a passage extending in a vertical direction, a feedwater preheater including a heat exchanger which is provided on the passage, configured to allow feedwater supplied to the boiler body to flow therethrough, and supply the feedwater to the boiler body after the feedwater is previously heated in the heat exchanger with the combustion gas flowing on the passage, and a feedwater temperature measuring unit configured to measure a feedwater temperature being the temperature of the feedwater flowing in the heat exchanger; and a combustion amount control unit configured to control combustion amount in the boiler, having a feedwater temperature threshold as a threshold relating to the feedwater temperature, the combustion amount control unit minimizing the combustion amount in the boiler in a case where the feedwater temperature measured by the feedwater temperature measuring unit is the feedwater temperature threshold or lower.