Method for heat rate improvement in partial-arc steam turbine
AssigneeWestinghouse Electric Corp.
InventorGeorge J. Silvestri, Jr.
Life of this patent
Estimating the term…
Abstract
Method for improving the heat rate of a steam turbine operated in a partial-arc mode includes sequential closing of control valves to establish a first arc of admission followed by a reduction of steam pressure to a predetermined level. Additional valves are closed to bring the admission arc to an optimum value and power reduction is thereafter affected by pressure reduction. In a further method, low power operation is achieved by reducing the arc of admission below optimum when steam pressure has been reduced to a minimum value.
Claims5
A method for reducing shock loading of control stage blading in a partial-arc steam turbine in which steam supply is controlled to match power demand, the turbine including a plurality of control valves each arranged for admitting steam to a predetermined arc of admission at the control stage blading, the method comprising the steps of:
- sequentially closing selected ones of the control valves to reduce the arc of admission to the minimum value permissible at full operating steam pressure;
- generally decreasing pressure to a value such that the pressure drop across the first control stage at a selected further reduced arc of admission does not exceed the pressure drop at the minimum value of admission arc with designed throttle pressure;
- closing additional selected ones of the control valves to reduce the arc of admission to the selected further reduced arc;
- and
- further decreasing steam pressure to maintain turbine power at the demand value.
A method for limiting pressure drop on control stage blading of a partial-arc steam turbine in which steam supply is controlled in order to match turbine power to power demand, the turbine including a plurality of control valves each arranged for admitting steam to a selected arc of admission into the control stage blading, the method comprising the steps of:
- sequentially closing predetermined ones of the control valves to reduce turbine power output by reducing the arc of admission to a first predetermined value;
- sliding steam pressure to a first reduced value to further reduce turbine power output while maintaining a constant arc of admission;
- sequentially closing additional ones of the control valves to further reduce the arc of admission to a second predetermined value and to reduce turbine output power toward demanded power while holding steam pressure at the first reduced value;
- and
- further sliding steam pressure to match turbine power to demanded power while holding the arc of admission at the second predetermined value.
Dependencies are inferred from the claim text.