| 摘要 |
PROBLEM TO BE SOLVED: To prevent boiler water from being boiled up by an economizer 4 in a feed water preheating boiler having the economizer 4 for pre-heating boiler supplied water under application of heat held by exhaust gas after heat recovery at a boiler main body 6 even if a pre-heating amount at the economizer 4 becomes higher than its set value.SOLUTION: This invention relates to a feed water preheating boiler comprising an economizer 4 for preheating fed water and a boiler main body 6 for further heating fed water preheated by the economizer 4 to generate steam so as to supply water to the boiler main body 6 through the economizer 4. There is provided a flow passage contraction part 12 at a flow passage 7 for flowing preheated water preheated by the economizer 4, a saturation temperature is increased by increasing a pressure at the economizer 4 and boiling at the economizer 4 is prevented. |
