To attain a sufficient corrosion inhibiting effect on a heat transfer surface of a boiler without using chemicals even if the concentration of a corrosion inhibiting component of the boiler in raw water is low.
A water supply line 3 to the boiler 2 is provided with a first membrane treatment part 4 having a function of eliminating corrosion accelerating components to the heat transfer surface of the boiler 2 and allowing the passage of corrosion inhibiting components to the heat transfer surface of the boiler 2, and a return line 5 for returning boiler water in the boiler 2 to the upstream side of the first membrane treatment part 4 is provided with a second membrane treatment part 6 having a function of eliminating the corrosion accelerating components to the heat transfer surface of the boiler 2 and allowing the passage of the corrosion inhibiting components to the heat transfer surface of the boiler 2.
MIURA PROTEC KK
Yasushi Kobayashi
Takeshi Kojima