| 摘要 |
A boiler economizer includes a first heat exchanger disposed in a boiler flue and a second heat exchanger which is external. Boiler feedwater is delivered in series to the first and second heat exchangers before passage to the boiler. A flow controller directs a first portion of the boiler feedwater directly to the first heat exchanger and a second portion is first delivered through the second heat exchanger where it is passed in a heat exchange relation with the feedwater exiting the first heat exchanger. The flow controller is positioned by a temperature transponder which is responsive to the temperature of the discharge flue gases and the feedwater entering the first heat exchanger.
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