A subcritical pressure high-temperature steam power plant includes a combustion boiler system, steam turbine generator system, and condensate and feedwater system and wherein the conditions of steam generated in the boiler system and supplied to the steam turbine generator system are subcritical pressure and high temperature (turbine inlet temperature of 593° C. or more).

A method including: (i) operating a pumped-heat energy storage system (“PHES system”) in a charge mode to convert electricity into stored thermal energy in a hot thermal storage medium (“HTS medium”) by transferring heat from a working fluid to a warm HTS medium, resulting in a hot HTS medium, wherein the PHES system is further operable in a generation mode to convert at least a portion of the stored thermal energy into electricity; and (ii) heating the hot HTS medium with an electric heater above a temperature achievable by transferring heat from the working fluid to the warm HTS medium.

The present disclosure provides pumped heat energy storage systems that can be used to store and/or extract electrical energy. A pumped heat energy storage system of the present disclosure can store energy by operating as a heat pump, whereby net work input can be used to transfer heat from the cold side to the hot side. A working fluid of the system is capable of efficient heat exchange with heat storage fluids on a hot side of the system and on a cold side of the system. Such pumped energy storage systems can be beneficially integrated with steam plants to provided heating to the steam cycle.

A first system herein may include: (i) a pumped-heat energy storage system (“PHES system”), wherein the PHES system is operable in a generation mode to convert at least a portion of stored thermal energy into electricity, wherein the PHES system includes a working fluid path circulating a working fluid through, in sequence, at least a compressor system, a hot-side heat exchanger system, a turbine system, a cold-side heat exchanger system, and back to the compressor system; and (ii) a fluid path directing a first fluid through an intercooler and to a power generation plant, and wherein the working fluid path through the compressor system includes circulating the working fluid through, in sequence, at least a first compressor, the intercooler, and a second compressor, and wherein the intercooler thermally contacts the working fluid with the first fluid, transferring heat from the working fluid to the first fluid.

A method including: (i) receiving a first amount of electricity into a pumped-heat energy storage system (“PHES system”) from a power generation plant supplying a second amount of electricity to an electrical grid; (ii) operating the PHES system in a charge mode, converting at least a portion of the received first amount of electricity to stored thermal energy; and (iii) increasing a power level of the PHES system such that the first amount of electricity that the PHES system receives from the power generation plant is increased such that the second amount of electricity supplied to the electrical grid by the power generation plant is a reduced amount of electricity less than the second amount of electricity.

A system including: a pumped-heat energy storage system (“PHES system”), wherein the PHES system is operable in a charge mode to convert electricity into stored thermal energy, wherein the PHES system comprises a working fluid path circulating a working fluid through, in sequence, at least a compressor system, a hot-side heat exchanger system, a turbine system, a cold-side heat exchanger system, and back to the compressor system; and (ii) a fluid path directing a hot fluid from a heat source external to the PHES system through a reheater, wherein a portion of the working fluid path through the turbine system comprises circulating the working fluid through a first turbine, the reheater, and a second turbine, and wherein the working fluid thermally contacts the hot fluid in the reheater, thereby transferring heat from the hot fluid to the working fluid.

A steam turbine plant is provided with: a plurality of steam turbines; a multistage pressure condenser composed of a plurality of condensers which are respectively provided below the respective steam turbines so as to correspond to the plurality of steam turbines, and in which steam which is discharged from the respective steam turbines is condensed and accommodated as condensate; and a steam extraction section which introduces some of the steam in the steam turbine into condensate of the condenser corresponding to the lowest-pressure steam turbine among the plurality of condensers.

A steam turbine plant is provided with: a plurality of steam turbines; a multistage pressure condenser composed of a plurality of condensers which are respectively provided below the respective steam turbines so as to correspond to the plurality of steam turbines, and in which steam which is discharged from the respective steam turbines is condensed and accommodated as condensate; and a steam extraction section which introduces some of the steam in the steam turbine into condensate of the condenser corresponding to the lowest-pressure steam turbine among the plurality of condensers.

Systems and methods axe disclosed herein that generally involve a double pinch criterion for optimization of regenerative Rankine cycles. In some embodiments, operating variables such as bleed extraction pressure and bleed flow rate are selected such that a double pinch is obtained in a feedwater heater, thereby improving the efficiency of the Rankine cycle. In particular, a first pinch point is obtained at the onset of condensation of the bleed and a second pinch point is obtained at the exit of the bleed from the feedwater heater. The minimal approach temperature at the first pinch point can be approximately equal to the minimal approach temperature at the second pinch point. Systems that employ regenerative Rankine cycles, methods of operating such systems, and methods of optimizing the operation of such systems are disclosed herein in connection with the double pinch criterion.

Systems and methods axe disclosed herein that generally involve a double pinch criterion for optimization of regenerative Rankine cycles. In some embodiments, operating variables such as bleed extraction pressure and bleed flow rate are selected such that a double pinch is obtained in a feedwater heater, thereby improving the efficiency of the Rankine cycle. In particular, a first pinch point is obtained at the onset of condensation of the bleed and a second pinch point is obtained at the exit of the bleed from the feedwater heater. The minimal approach temperature at the first pinch point can be approximately equal to the minimal approach temperature at the second pinch point. Systems that employ regenerative Rankine cycles, methods of operating such systems, and methods of optimizing the operation of such systems are disclosed herein in connection with the double pinch criterion.