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 combined cycle power plant that includes a gas turbine and HRSG engaged with a steam turbine via a water steam cycle having higher and lower pressure levels. The CCPP further includes a fuel line and fuel preheater. A higher pressure feedwater line delivers higher pressure feedwater to a higher pressure feedwater branch that extends through the fuel preheater, the high pressure feedwater branch including upstream and downstream segments defined to each side of the fuel preheater. A lower pressure feedwater line delivers lower pressure feedwater to a lower pressure feedwater branch. The downstream segment of the higher pressure feedwater branch is combined with the lower pressure feedwater branch at a junction point and a combined feedwater line extends therefrom. A first heat exchanger exchanges heat between the combined feedwater line and fuel line. A second heat exchanger exchanges heat between the higher pressure feedwater branch and fuel line.

A combined cycle power plant that includes a gas turbine and HRSG engaged with a steam turbine via a water steam cycle having higher and lower pressure levels. The CCPP further includes a fuel line and fuel preheater. A higher pressure feedwater line delivers higher pressure feedwater to a higher pressure feedwater branch that extends through the fuel preheater, the high pressure feedwater branch including upstream and downstream segments defined to each side of the fuel preheater. A lower pressure feedwater line delivers lower pressure feedwater to a lower pressure feedwater branch. The downstream segment of the higher pressure feedwater branch is combined with the lower pressure feedwater branch at a junction point and a combined feedwater line extends therefrom. A first heat exchanger exchanges heat between the combined feedwater line and fuel line. A second heat exchanger exchanges heat between the higher pressure feedwater branch and fuel line.

A method of operating a combined heat and power plant (10) (CHP plant) includes generating hot flue gas and cooling the hot flue gas in a sequence of cooling steps to recover heat and to generate steam in a heat recovery steam generator (16) (HRSG). The HRSG (16) includes an LP steam evaporator (36) designed to generate steam at least over a pressure range of from 2 bar(g) to 18 bar(g) so that either LP steam or MP steam can selectively be generated by the LP steam generator (36), thereby to cool the hot flue gas, and an MP steam superheater (24) upstream of the LP steam evaporator (36) to superheat MP steam in heat exchange with the hot flue gas thereby to cool the hot flue gas. The method further includes, when no or insufficient MP steam is being imported to the MP steam superheater (24) to ensure safe operation of the MP steam superheater, and/or when a demand exists for exporting MP steam which cannot be satisfied by imported MP steam superheated in the MP steam superheater (24), and/or when a demand exists for MP steam in the CHP plant which cannot be satisfied by imported MP steam, operating the LP steam evaporator (36) at an operating pressure in the range of between 8 bar(g) and 18 bar(g) to generate MP steam to wet the MP steam superheater (24) and/or to satisfy at least to some extent said demand for MP steam, and thereafter, when sufficient MP steam is being imported to the MP steam superheater (24) from external of the CHP plant (10) to ensure safe operation of the MP steam superheater (24), and/or when any demand for exported MP steam is satisfied by imported MP steam which is superheated in the MP steam superheater (24) and then exported, and/or when there is no more demand for exporting of MP steam, and/or when the demand for MP steam in the CHP plant (10) is being satisfied at least to some extent by imported MP steam, reducing the operating pressure of the LP steam evaporator (36) to a pressure in the range of between 2 bar(g) and 8 bar(g) thereby to generate LP steam.

A method of operating a combined heat and power plant (10) (CHP plant) includes generating hot flue gas and cooling the hot flue gas in a sequence of cooling steps to recover heat and to generate steam in a heat recovery steam generator (16) (HRSG). The HRSG (16) includes an LP steam evaporator (36) designed to generate steam at least over a pressure range of from 2 bar(g) to 18 bar(g) so that either LP steam or MP steam can selectively be generated by the LP steam generator (36), thereby to cool the hot flue gas, and an MP steam superheater (24) upstream of the LP steam evaporator (36) to superheat MP steam in heat exchange with the hot flue gas thereby to cool the hot flue gas. The method further includes, when no or insufficient MP steam is being imported to the MP steam superheater (24) to ensure safe operation of the MP steam superheater, and/or when a demand exists for exporting MP steam which cannot be satisfied by imported MP steam superheated in the MP steam superheater (24), and/or when a demand exists for MP steam in the CHP plant which cannot be satisfied by imported MP steam, operating the LP steam evaporator (36) at an operating pressure in the range of between 8 bar(g) and 18 bar(g) to generate MP steam to wet the MP steam superheater (24) and/or to satisfy at least to some extent said demand for MP steam, and thereafter, when sufficient MP steam is being imported to the MP steam superheater (24) from external of the CHP plant (10) to ensure safe operation of the MP steam superheater (24), and/or when any demand for exported MP steam is satisfied by imported MP steam which is superheated in the MP steam superheater (24) and then exported, and/or when there is no more demand for exporting of MP steam, and/or when the demand for MP steam in the CHP plant (10) is being satisfied at least to some extent by imported MP steam, reducing the operating pressure of the LP steam evaporator (36) to a pressure in the range of between 2 bar(g) and 8 bar(g) thereby to generate LP steam.

An assembly with a steam turbine and an overload valve, wherein the overload valve is arranged opposite the fresh steam valve and a fresh steam flows partially through the flow channel and partially into an overload inflow region via the overload valve.

An expansion apparatus for recovering waste heat may include two or more turbines and a distribution valve distributing working fluid supplied from the boiler to the two or more turbines, wherein the two or more turbines include a power turbine and one or more auxiliary turbines, and the power turbine is configured to receive a larger amount of working fluid than the one or more auxiliary turbines.

The invention ECT relates to methods for improving the amount of electricity gained from preferably waste heat by a normal or an organic (ORC) Rankine process with vaporization in several stages, normally three. The waste heat in sensible form is exchanged in at least two in series coupled evaporators to a receiving working fluid (e.g. a refrigerant) that passes at least two of said evaporators, but coupled in parallel. Of the waste heat between the temperature of the heat source and that of the heat sink about 80% can be used for direct electricity generation. An embodiment of the invention uses a radial turbine with a centripetal (inwards) flow direction. The different vapor enthalpies from the said vaporization stages enters a turbine wheel/runner 51 at different outside diameters D2, D2 and/or with suitable tangential velocities obtained by different guiding vane sets 65, 66 and 67.

The invention ECT relates to methods for improving the amount of electricity gained from preferably waste heat by a normal or an organic (ORC) Rankine process with vaporization in several stages, normally three. The waste heat in sensible form is exchanged in at least two in series coupled evaporators to a receiving working fluid (e.g. a refrigerant) that passes at least two of said evaporators, but coupled in parallel. Of the waste heat between the temperature of the heat source and that of the heat sink about 80% can be used for direct electricity generation. An embodiment of the invention uses a radial turbine with a centripetal (inwards) flow direction. The different vapor enthalpies from the said vaporization stages enters a turbine wheel/runner 51 at different outside diameters D2, D2 and/or with suitable tangential velocities obtained by different guiding vane sets 65, 66 and 67.