Systems and methods are provided for the recovery mechanical power from heat energy sources using a common working fluid comprising, in some embodiments, an organic refrigerant flowing through multiple heat exchangers and expanders. The distribution of heat energy from the source may be portioned, distributed, and communicated to each of the heat exchangers so as to permit utilization of up to all available heat energy. In some embodiments, the system utilizes up to and including all of the available heat energy from the source. The expanders may be operatively coupled to one or more generators that convert the mechanical energy of the expansion process into electrical energy, or the mechanical energy may be communicated to other devices to perform work.

A method for operating a combined cycle power plant (CCPP) and improving a part load operation of the CCPP is provided. The CCPP may include at least a gas turbine, a heat recovery steam generator (HRSG) located downstream of the gas turbine, a main steam turbine, and a supercritical steam turbine. The HRSG may include a low pressure steam system, an intermediate pressure steam system, and a high pressure steam system. To improve the part load efficiency of the CCPP, a base load operation of the CCPP may be initiated with supercritical pressure, via the supercritical steam turbine, such that the efficiency impact resulting from the part load operation is reduced.

A method for operating a combined cycle power plant (CCPP) and improving a part load operation of the CCPP is provided. The CCPP may include at least a gas turbine, a heat recovery steam generator (HRSG) located downstream of the gas turbine, a main steam turbine, and a supercritical steam turbine. The HRSG may include a low pressure steam system, an intermediate pressure steam system, and a high pressure steam system. To improve the part load efficiency of the CCPP, a base load operation of the CCPP may be initiated with supercritical pressure, via the supercritical steam turbine, such that the efficiency impact resulting from the part load operation is reduced.

A steam turbine according to at least one embodiment of the present disclosure includes an outer casing. The steam turbine according to at least one embodiment of the present disclosure includes an annular member, which is a single member provided radially inward of the outer casing, and formed in the annular member are a seal region in which a sealing device for sealing a gap between said member and the outer peripheral surface of a rotor is located, a rear-stage-stator-vane-holding region where a rear-stage stator vane is held, and an inner casing region connecting the seal region and the rear-stage-stator-vane-holding region. The steam turbine according to at least one embodiment of the present disclosure includes a front-stage vane ring that is attached to the annular member and that holds a front-stage stator vane.

A steam turbine plant of one embodiment includes at least one heater configured to change water into steam to produce high pressure steam and low pressure steam having a lower pressure than the high pressure steam, a high pressure turbine including a turbine or turbines connected to each other in series, and having a first inlet to supply the high pressure steam, a second inlet to supply the low pressure steam and located at a downstream of the first inlet, and an exhaust port located at a downstream of the second inlet, the high pressure turbine being configured to be driven by the steam supplied from the first and second inlets, a reheater configured to heat the steam exhausted from the exhaust port, and a reheat turbine configured to be driven by the steam from the reheater.

A steam turbine plant of one embodiment includes at least one heater configured to change water into steam to produce high pressure steam and low pressure steam having a lower pressure than the high pressure steam, a high pressure turbine including a turbine or turbines connected to each other in series, and having a first inlet to supply the high pressure steam, a second inlet to supply the low pressure steam and located at a downstream of the first inlet, and an exhaust port located at a downstream of the second inlet, the high pressure turbine being configured to be driven by the steam supplied from the first and second inlets, a reheater configured to heat the steam exhausted from the exhaust port, and a reheat turbine configured to be driven by the steam from the reheater.

An axial-flow turbine according to an embodiment includes a plurality of nozzle structures and a plurality of blade structures. At least one nozzle structure includes an outer ring diaphragm and an inner ring diaphragm. The outer ring diaphragm and the inner ring diaphragm form an annular opening portion which extends in a circumferential direction therebetween. A nozzle is provided in a portion of a region of the annular opening portion in the circumferential direction, and a closing part is provided in another portion of the region of the annular opening portion in the circumferential direction. The closing part closes this other portion of the region to prevent a working fluid from flowing into this other portion of the region. A closing part medium passage is provided in the closing part and is configured to flow a cooling medium which cools the closing part.

A method to operate a steam turbine, a steam turbine, and a concentrated solar power plant with at least a first turbine module with a first stage and at least one second stage, wherein the stages are successively arranged in the flow direction of the steam, a main inlet for channelling steam to the first stage and a bypass arranged parallel to the main inlet for channelling steam to the at least one second stage.

A waste heat recovery system includes a high pressure turbine and a low pressure turbine, in which the high pressure turbine receives high pressure working fluid vapor, the low pressure turbine receives low pressure working fluid vapor and the high pressure turbine also supplies low pressure working fluid vapor to the low pressure turbine. A recuperator receives working fluid vapor from the low pressure turbine. The recuperator produces heated condensate, at least a portion of which is provided to a high pressure vaporizer. The high pressure vaporizer is configured to receive from a high temperature heat source and produces high pressure working vapor used to power the high pressure turbine. The remaining condensed fluid is provided to a low pressure vaporizer which is configured to receive heat from a low-temperature heat source, thereby producing low pressure working fluid vapor used to power the low pressure turbine.

A waste heat recovery system includes a high pressure turbine and a low pressure turbine, in which the high pressure turbine receives high pressure working fluid vapor, the low pressure turbine receives low pressure working fluid vapor and the high pressure turbine also supplies low pressure working fluid vapor to the low pressure turbine. A recuperator receives working fluid vapor from the low pressure turbine. The recuperator produces heated condensate, at least a portion of which is provided to a high pressure vaporizer. The high pressure vaporizer is configured to receive from a high temperature heat source and produces high pressure working vapor used to power the high pressure turbine. The remaining condensed fluid is provided to a low pressure vaporizer which is configured to receive heat from a low-temperature heat source, thereby producing low pressure working fluid vapor used to power the low pressure turbine.