| 摘要 |
PURPOSE:To perform effective heat recovery by a method wherein heating of desired fluid is performed by passing hot water through a first and a second heat exchangers and as well as the temperature of the hot water at the inlet side of the first heat exchanger is controlled to be higher than the set temperature based upon the measured value of the acid dew point of combustion exhaust gas. CONSTITUTION:The acid dew point indicator 11 of combustion exhaust gas is provided in the low temperature exhaust gas passage of a boiler 1 at the inlet side of the first heat exchanger 5 so as to send the measured acid dew point to a hot water temperature setter 12 in order to obtain the set hot water temperature. Furthermore, the temperature detected with a hot water thermometer 19 is sent to a hot water temperature controlling unit 14 in order to compare said hot water temperature with said set hot water temperature so as to convert the difference between both said temperatures into a controlling signal. By the actuations of the steam flow regulating valve 20 in a steam pipe 13 for heating hot water and of a regulating valve 21 for controlling the amount of circulating hot water, both of which are actuated by the controlling signal, the temperature of the hot water supplied to the inlet side of the first heat exchanger 5 is automatically controlled and the corrosion occurred at the low temperature part in the exhaust gas passage is prevented. |
