A water feeding system provided with: a first feed water line through which first feed water flows; a second feed water line through which second feed water having a lower pressure than the first feed water flows; a first heater that heats the first feed water; a first feed water introducing line that guides first heated feed water, which is the first feed water that has been heated by the first heater, to the second feed water line; a medium heat exchanger that causes the first heated feed water to exchange heat with a medium, thereby cooling the first heated feed water and heating the medium; and a cooling water injecting line that injects cooling water having a lower temperature than the first heated feed water into the first feed water introducing line, at a position located further to the second feed water line side than the medium heat exchanger.

A water feeding system provided with: a first feed water line through which first feed water flows; a second feed water line through which second feed water having a lower pressure than the first feed water flows; a first heater that heats the first feed water; a first feed water introducing line that guides first heated feed water, which is the first feed water that has been heated by the first heater, to the second feed water line; a medium heat exchanger that causes the first heated feed water to exchange heat with a medium, thereby cooling the first heated feed water and heating the medium; and a cooling water injecting line that injects cooling water having a lower temperature than the first heated feed water into the first feed water introducing line, at a position located further to the second feed water line side than the medium heat exchanger.

A water feeding system provided with: a first feed water line through which first feed water flows; a second feed water line through which second feed water having a lower pressure than the first feed water flows; a first heater that heats the first feed water; a first feed water introducing line that guides first heated feed water, which is the first feed water that has been heated by the first heater, to the second feed water line; a medium heat exchanger that causes the first heated feed water to exchange heat with a medium, thereby cooling the first heated feed water and heating the medium; and a cooling water injecting line that injects cooling water having a lower temperature than the first heated feed water into the first feed water introducing line, at a position located further to the second feed water line side than the medium heat exchanger.

A water feeding system provided with: a first feed water line through which first feed water flows; a second feed water line through which second feed water having a lower pressure than the first feed water flows; a first heater that heats the first feed water; a first feed water introducing line that guides first heated feed water, which is the first feed water that has been heated by the first heater, to the second feed water line; a medium heat exchanger that causes the first heated feed water to exchange heat with a medium, thereby cooling the first heated feed water and heating the medium; and a cooling water injecting line that injects cooling water having a lower temperature than the first heated feed water into the first feed water introducing line, at a position located further to the second feed water line side than the medium heat exchanger.

A feed-water discharge side of a condenser is connected to a feed-water entry side of an flue gas cooler through a bypass line provided with a steam production preventive pump and with an inlet cutoff valve. A feed-water discharge side of the flue gas cooler is connected to the feed-water entry side of the condenser through a steam production preventive water circulation line provided with an outlet cutoff valve. When a boiler feed-water pump is stopped in boiler fuel cutoff, the inlet and outlet cutoff valves are opened and the steam production preventive pump is activated to cause water to flow through the bypass line into the flue gas cooler, is returned through the steam production preventive water circulation line to the condenser and is circulated.

A feed-water discharge side of a condenser is connected to a feed-water entry side of an flue gas cooler through a bypass line provided with a steam production preventive pump and with an inlet cutoff valve. A feed-water discharge side of the flue gas cooler is connected to the feed-water entry side of the condenser through a steam production preventive water circulation line provided with an outlet cutoff valve. When a boiler feed-water pump is stopped in boiler fuel cutoff, the inlet and outlet cutoff valves are opened and the steam production preventive pump is activated to cause water to flow through the bypass line into the flue gas cooler, is returned through the steam production preventive water circulation line to the condenser and is circulated.