A system for readying sub-critical and super-critical steam generator, a servicing method of the sub-critical and the super-critical steam generator and a method of operation of sub-critical and super-critical steam generator is provided. The steam generator includes a first auxiliary heating device disposed on at least one water-steam separator for heating the at least one water-steam separator, and/or a second auxiliary heating device disposed at least on a part of furnace top-end piping for heating the furnace top-end piping. The auxiliary heating devices are heating steam producing components of the steam generator and thus allowing to keep them above the temperature in which materials creating the steam producing components are brittle. The method includes recirculation of the water through the steam generator.

A system for readying sub-critical and super-critical steam generator, a servicing method of the sub-critical and the super-critical steam generator and a method of operation of sub-critical and super-critical steam generator is provided. The steam generator includes a first auxiliary heating device disposed on at least one water-steam separator for heating the at least one water-steam separator, and/or a second auxiliary heating device disposed at least on a part of furnace top-end piping for heating the furnace top-end piping. The auxiliary heating devices are heating steam producing components of the steam generator and thus allowing to keep them above the temperature in which materials creating the steam producing components are brittle. The method includes recirculation of the water through the steam generator.

Method for controlling steam admission into a steam turbine, the turbine comprising a high pressure casing, at least one reduced pressure casing and an admission steam control system, the high pressure casing and at least one reduced pressure casing comprising control valves for steam admission. The steam admission control system manages the following steps: determining at least one of the speed and the acceleration of the turbine; comparing the determined speed and/or acceleration respectively with a predefined speed threshold value and a predefined acceleration threshold value; when the determined speed and/or acceleration are superior to the predefined threshold value, the control system activates a speed and acceleration limiter.

In one embodiment, a plant control apparatus controls a power plant. The plant includes a gas turbine, a generator driven by the gas turbine, an exhaust heat recovering boiler to generate first steam by using heat of exhaust gas from the gas turbine, a first steam turbine driven by the first steam, a reheater provided in the boiler and configured to heat exhaust steam from the first steam turbine by the exhaust gas to generate reheat steam, and a second steam turbine driven by the reheat steam. The apparatus includes a first warming-up module to supply second steam from equipment different from the boiler to the first steam turbine to warm up this turbine, before this turbine is started. The apparatus further includes a second warming-up module to supply the second steam to the reheater to warm up the reheater, before the first steam turbine is started.

In one embodiment, a plant control apparatus controls a power plant. The plant includes a gas turbine, a generator driven by the gas turbine, an exhaust heat recovering boiler to generate first steam by using heat of exhaust gas from the gas turbine, a first steam turbine driven by the first steam, a reheater provided in the boiler and configured to heat exhaust steam from the first steam turbine by the exhaust gas to generate reheat steam, and a second steam turbine driven by the reheat steam. The apparatus includes a first warming-up module to supply second steam from equipment different from the boiler to the first steam turbine to warm up this turbine, before this turbine is started. The apparatus further includes a second warming-up module to supply the second steam to the reheater to warm up the reheater, before the first steam turbine is started.

A first steam turbine and a second steam turbine of a combined cycle plant are connected by a reheat steam line via a reheat section of an exhaust heat recovery boiler. The reheat steam line and a condenser are connected by a second bypass line. A control device includes: a determination unit that determines whether or not the flow rate of first steam flowing into the first steam turbine has reached a stipulated flow rate; a command output unit that, upon determining that the flow rate of the first steam flowing into the first steam turbine has reached the stipulated flow rate, outputs a close command to close a ventilator valve that is provided in the second bypass line and is open; and a threshold alteration unit that alters the threshold with which the determination unit determines whether or not the stipulated flow rate has been reached, the threshold being positively correlated with a temperature of the first steam.

A first steam turbine and a second steam turbine of a combined cycle plant are connected by a reheat steam line via a reheat section of an exhaust heat recovery boiler. The reheat steam line and a condenser are connected by a second bypass line. A control device includes: a determination unit that determines whether or not the flow rate of first steam flowing into the first steam turbine has reached a stipulated flow rate; a command output unit that, upon determining that the flow rate of the first steam flowing into the first steam turbine has reached the stipulated flow rate, outputs a close command to close a ventilator valve that is provided in the second bypass line and is open; and a threshold alteration unit that alters the threshold with which the determination unit determines whether or not the stipulated flow rate has been reached, the threshold being positively correlated with a temperature of the first steam.

A boiler includes one or more evaporators configured to heat water which has flowed therein to a specific heat maximum temperature at constant pressure or more in which a specific heat at constant pressure is maximized using a heated fluid and one or more reheaters configured to heat the steam which has come from the boiler using the heated fluid. All the reheaters configured to supply steam to a low-pressure steam turbine are disposed only at a downstream side of the high-pressure evaporator. All the reheaters heat reheating steam (FRHS) containing steam which has passed through a high-pressure steam turbine configured to receive steam supplied from the high-pressure evaporator and having a temperature lower than a specific heat maximum temperature at constant pressure in the high-pressure evaporator to less than the specific heat maximum temperature at constant pressure.

A boiler includes one or more evaporators configured to heat water which has flowed therein to a specific heat maximum temperature at constant pressure or more in which a specific heat at constant pressure is maximized using a heated fluid and one or more reheaters configured to heat the steam which has come from the boiler using the heated fluid. All the reheaters configured to supply steam to a low-pressure steam turbine are disposed only at a downstream side of the high-pressure evaporator. All the reheaters heat reheating steam (FRHS) containing steam which has passed through a high-pressure steam turbine configured to receive steam supplied from the high-pressure evaporator and having a temperature lower than a specific heat maximum temperature at constant pressure in the high-pressure evaporator to less than the specific heat maximum temperature at constant pressure.

A system for readying sub-critical and super-critical steam generator, a servicing method of the sub-critical and the super-critical steam generator and a method of operation of sub-critical and super-critical steam generator is provided. The steam generator includes a first auxiliary heating device disposed on at least one water-steam separator for heating the at least one water-steam separator, and/or a second auxiliary heating device disposed at least on a part of furnace top-end piping for heating the furnace top-end piping. The auxiliary heating devices are heating steam producing components of the steam generator and thus allowing to keep them above the temperature in which materials creating the steam producing components are brittle. The method includes recirculation of the water through the steam generator.