A method for preheating untreated water in a power plant having a water/steam circuit, the power plant has a steam producer, a steam turbine, and steam lines, of which at least some connect the steam producer to the steam turbine, wherein untreated water for producing deionized water is heated by means of wastewater from the water/steam circuit and the wastewater is added to the untreated water in order to heat the untreated water. A power plant is adapted for preheating untreated water by the method.

A fluid recirculation system includes an arrangement of a flow control valve located to receive a flow of fluid from an inlet. The system further comprises an economizer inlet mixing device located to receive the flow of hotter fluid from the arrangement of the flow control valve and from a cooler feedwater stream. An economizer inlet mixing device located upstream of an economizer in a supercritical pressure boiler includes a sparger assembly through which a flow of fluid from the waterwall outlet is received, an inlet through which a flow of fluid from a feed stream is received, and a wave breaker assembly through which an outlet stream from the economizer inlet mixing device is directed.

A fluid recirculation system includes an arrangement of a flow control valve located to receive a flow of fluid from an inlet. The system further comprises an economizer inlet mixing device located to receive the flow of hotter fluid from the arrangement of the flow control valve and from a cooler feedwater stream. An economizer inlet mixing device located upstream of an economizer in a supercritical pressure boiler includes a sparger assembly through which a flow of fluid from the waterwall outlet is received, an inlet through which a flow of fluid from a feed stream is received, and a wave breaker assembly through which an outlet stream from the economizer inlet mixing device is directed.

A heat recovery apparatus recovers steam drain including at least one of steam used in a different device and drain where the steam used in the different device is condensed so as to recover heat contained in the steam drain. The heat recovery apparatus includes a pump, which circulates water accumulated in a tank through circulation pipes, an ejector, which is interposed in the circulation pipes and suctions the steam drain and mixes the steam drain with the circulating water so as to recover the steam drain, and a ball tap and a temperature controller, which perform temperature control of the water in the tank by replenishing the tank with tap water after a part of the water in the tank is discharged in the case where the water in the tank has reached a preliminarily set first temperature.

A heat recovery apparatus recovers steam drain including at least one of steam used in a different device and drain where the steam used in the different device is condensed so as to recover heat contained in the steam drain. The heat recovery apparatus includes a pump, which circulates water accumulated in a tank through circulation pipes, an ejector, which is interposed in the circulation pipes and suctions the steam drain and mixes the steam drain with the circulating water so as to recover the steam drain, and a ball tap and a temperature controller, which perform temperature control of the water in the tank by replenishing the tank with tap water after a part of the water in the tank is discharged in the case where the water in the tank has reached a preliminarily set first temperature.

In a drain recovery section including a recovery tank to which drain generated in a steam-using device is collected and from which the drain is supplied to a boiler, pressure decrease in the boiler under a high load can be suppressed. A drain recovery section includes: a recovery tank in which drain generated by condensation of steam in a steam-using device is stored and from which water stored in the recovery tank is supplied to a boiler; and a control unit that controls an amount of water supply from the recovery tank to the boiler to prevent the water level of water in the recovery tank from decreasing below a predetermined tank reference water level. When the load of the boiler increases to a predetermined load, the control unit reduces the tank reference water level by a predetermined amount.