Technical specification of turbomachinery rerates

摘要

Performance 'rerating' of existing turbomachinery typically involves incrementing the power from a turbine or adjusting the flow-speed relationship of a compressor to reflect changes in plant requirements. Rerating can be more cost-effective than the purchase of new equipment, particularly when new hardware is already required during a scheduled machine overhaul. The technical challenge is to achieve the desired performance with minimal changes to the hardware, and certainly within the existing casings. Some of the methods used to determine the necessary hardware modifications are illustrated via the detail of a steam turbine rerate.