A steam power generating system includes at least one steam generator, at least one turbine assembly, at least one electric generator, at least one condenser and a feedwater preheat arrangement including at least one injection feedwater heater connected to the condenser and the turbine assembly. The injection feedwater heater includes a main heater body and at least one injection nozzle. A predetermined amount of condensate water from the condenser is arranged to be pumped into the main heater body. The condensate water passing through the water inlet is arranged to be injected into a heat exchange compartment through the injection nozzle for creating a negative pressure in the heat exchange compartment. The negative pressure draws a predetermined amount of steam from the turbine assembly to enter the heat exchange compartment for mixing with the condensate water.

An injection feedwater heater for a steam power generating system includes at least one main heater body and at least one injection nozzle. The main heater body has at least one heat exchange compartment, at least one water inlet, at least one steam inlet, and at least one water outlet formed on the main heater body. The injection nozzle is provided in the main heater body at a position adjacent to the water inlet, wherein a predetermined amount of condensate water is arranged to be pumped into the main heater body through the water inlet. The condensate water passing through the water inlet is arranged to be injected into the heat exchange compartment through the injection nozzle for creating a negative pressure in the heat exchange compartment. The negative pressure drawing a predetermined amount of steam to enter the heat exchange compartment for mixing with the condensate water.

A system and method for warmkeeping a steam generator such as a sub-critical steam generator is disclosed. Water extraction piping extracts water from a component of one of the water fill circuits of the sub-critical steam generator. A deaerator heating system having an inventory tank of water mixes the extracted water with the water in the tank, and heats the mix of water to a predetermined temperature level to generate heated deaerated feedwater. Feedwater piping forwards the heated deaerated feedwater at the predetermined temperature level from the deaerator heating system to the water fill circuits of the sub-critical steam generator. The water extraction piping, the deaerator heating system and the feedwater piping operate cooperatively to warmkeep the water fill circuits in accordance with the predetermined temperature level while the sub-critical steam generator is in the unfired stand-by mode of operation.

A system and method for warmkeeping a steam generator such as a sub-critical steam generator is disclosed. Water extraction piping extracts water from a component of one of the water fill circuits of the sub-critical steam generator. A deaerator heating system having an inventory tank of water mixes the extracted water with the water in the tank, and heats the mix of water to a predetermined temperature level to generate heated deaerated feedwater. Feedwater piping forwards the heated deaerated feedwater at the predetermined temperature level from the deaerator heating system to the water fill circuits of the sub-critical steam generator. The water extraction piping, the deaerator heating system and the feedwater piping operate cooperatively to warmkeep the water fill circuits in accordance with the predetermined temperature level while the sub-critical steam generator is in the unfired stand-by mode of operation.

A method of suppressing steam production in a HRSG where a volume of feed water is diverted upstream bypassing a portion of the economizer and returning the volume of diverted feed water to a downstream portion of the economizer. A control logic circuit is used to manipulate a suppression control valve regulating the bypassed feed water, thereby reducing the temperature of water in the steam drum. Bypassing feed water flow into a downstream portion of an economizer reduces the steam production rate in the steam drum by increasing the evaporator approach temperature, permitting gas turbines to operate at base load even after an upgrade, by preventing the waste heat boiler from exceeding its rated capacity and pressure.

A method of suppressing steam production in a HRSG where a volume of feed water is diverted upstream bypassing a portion of the economizer and returning the volume of diverted feed water to a downstream portion of the economizer. A control logic circuit is used to manipulate a suppression control valve regulating the bypassed feed water, thereby reducing the temperature of water in the steam drum. Bypassing feed water flow into a downstream portion of an economizer reduces the steam production rate in the steam drum by increasing the evaporator approach temperature, permitting gas turbines to operate at base load even after an upgrade, by preventing the waste heat boiler from exceeding its rated capacity and pressure.

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.

A spray nozzle and a deaerator each include an external cylinder provided with a plurality of jetting outlets on an outer circumference portion thereof, an inner cylinder that is supported inside the external cylinder so as to be movable in an axial center direction and is provided with a plurality of first communication holes capable of communicating with the jetting outlets, and an open-close valve that includes a shaft coupled to the inner cylinder and a valve body provided at a distal end portion of the shaft and capable of opening and closing a distal opening of the external cylinder. The spray nozzle and the deaerator thus structured provide improved performance by preventing an increase in pressure loss occurring regardless of a jet flow amount.

A spray nozzle and a deaerator each include an external cylinder provided with a plurality of jetting outlets on an outer circumference portion thereof, an inner cylinder that is supported inside the external cylinder so as to be movable in an axial center direction and is provided with a plurality of first communication holes capable of communicating with the jetting outlets, and an open-close valve that includes a shaft coupled to the inner cylinder and a valve body provided at a distal end portion of the shaft and capable of opening and closing a distal opening of the external cylinder. The spray nozzle and the deaerator thus structured provide improved performance by preventing an increase in pressure loss occurring regardless of a jet flow amount.

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.