Steam turbine start-up can be a significant contributor to overall combined-cycle start time and variability due to complex processes with multiple operator touch points and conservative operating limits. OpFlex is an integrated, plant-level control approach. This level of automation provides enhanced combined cycle start times, reduced variability, and reduced fuel consumption.
Steam Turbine AGILITY is a comprehensive system solution to improve start times of combined-cycle plants. It includes a combination of controls upgrades with expert plant-level operational analysis and recommendations to deliver significant improvements in combined-cycle start performance.
Improved startup reliability—reduced potential for missing generation during peak periods.
GE has developed a robust system to allow customers the flexibility during start-up by ensuring temperature uniformity across shells.
This upgrade is intended for the HP/IP shell (single-shell configuration), and is designed to enable the unit to maintain a set temperature for the turbine shell, and to reduce transient shell deflections, also targeting reduced seal wear corresponding to longer sustained HP/IP section efficiencies.
When combined with GE AGILITY™ offering, there will be added benefit in reduction of start times (cold, warm, and hot). The offering consists of a heating blanket system, junction boxes, cabling, thermocouples, and a stand-alone control system.
The STHCS uses heated air to keep the high-temperature rotors warm during periods of standstill and prior to re-start. This solution reduces start-up times by eliminating cold start conditions as well as providing preservation of the steam turbine and condenser by maintaining humidity control when the unit is in stand-still mode.
Implementing the ST heat conservation system will prevent the steam turbine from entering a cold condition after the shutdown. The warm-keeping of the ST leads to the following benefits:
The power generation industry is rapidly changing, and turbines originally manufactured for base-load operation are now required to respond quickly to grid demands. The modern requirements for steam turbine power plants (including combined-cycle installations) are faster and more frequent start-ups, combined with longer phases of low load operation (LLO).
GE has developed a modern rotor stress controller called Turbomax* 7+—available for units running older versions of Turbomax*—that is built around the following modules:
Calculates the thermal stresses for the steam turbine rotors based upon existing measurements typically available in the turbine supervisory instrumentation suite.
Accumulates lifetime consumption during operation caused by thermal low-cycle fatigue and creep. This indicator adapts to the changing use of the asset over time.
Keeps the operation of the steam turbine within the permissible limits for protection of the asset.
Turbomax* offers several benefits for operating and maintaining the steam turbine:
*Trademark of General Electric Company
**Control system limitations may apply