The invention discloses an energy-saving method and an energy-saving device for a boiler. Heat exchange on high-temperature
boiler feedwater at the temperature
ranging from 105 DEG C to 130 DEG C is carried out through a
boiler feedwater temperature reduction device, so that the temperature falls to range from 30 DEG C to 80 DEG C; then heat exchange between the
boiler feedwater ranging from 30 DEG C to 80 DEG C and boiler
smoke is carried out through a boiler
economizer, so that the boiler exhausted
smoke temperature falls to range from 100 DEG C to 130 DEG C; and the high-temperature boiler feedwater obtained after heat exchange enters a boiler
system. The energy-saving device comprises the boiler and the boiler
economizer, and further comprises the boiler feedwater temperature reduction device; a first boiler feedwater inlet of the boiler feedwater temperature reduction device is connected with a
boiler feedwater pump, and a first boiler feedwater outlet of the boiler feedwater temperature reduction device is connected with a second boiler feedwater inlet of the boiler
economizer; and a second boiler feedwater outlet of the boiler economizer is connected with a water inlet of the boiler, and the boiler feedwater temperature reduction device is further provided with a
cold medium inlet and a hot medium outlet. As the energy-saving method and the energy-saving device are used for conducting energy-saving transformation on the boiler, the boiler exhausted
smoke temperature can be reduced by more than 10 DEG C to 60 DEG C, and the boiler heat efficiency can be improved by more than 2%.