Fault Tolerant Thermal Control of Steam Turbine Shell Deflections

The metal-to-metal clearances of a steam turbine during full or part load operation are among the main drivers of efficiency. The requirement to add clearances is driven by a number of factors including the relative movements of the steam turbine shell and rotor during transient conditions such as startup and shutdown. This paper includes a description of a control algorithm to manage external heating blankets for the thermal control of the shell deflections during turbine shutdown. The proposed method is tolerant of changes in the heat loss characteristics of the system as well as simultaneous component failures.