Boiler feedwater system and boiler equipped therewith, and a control method for a boiler water supply system

摘要

The present invention addresses the problem of preventing low-temperature corrosion of a feed-water heating device, installing a feed-water heating device so as to save space and suppress cost, and suppressing a drop in the water level in a drum. A boiler feed-water system is provided with a feed-water system (21) that has: a first route (21a) that feeds water to a feed-water heating economizer (2) that allows water, whose heat is exchanged with boiler water located inside a steam drum (11), to exchange heat with exhaust gas from a furnace; a second route (21b) that branches off from the first route (21a) before heat exchange with the boiler water occurs, bypasses the steam drum (11), and joins with the first route (21a) at a confluence point (X); and a third route (21c) that branches off from the second route (21b) and feeds water to the steam drum (11). The boiler feed-water system is further provided with: a temperature detection unit (24) that detects the temperature of water between the confluence point (X) and the feed-water heating economizer (2); a flow-rate regulation unit (25) that regulates the flow-rate of water flowing in the feed-water system (21); and a control unit that regulates the flow-rate such the water temperature detected by the temperature detection unit (24) is kept at or above a prescribed temperature that prevents low-temperature corrosion of the feed-water heating economizer (2).