Bucket tip clearance control system

This invention relates generally to land-based, i.e., industrial gas turbines and, more particularly, to a gas turbine bucket tip clearance control system including a flow circuit within a turbine outer shroud that controls a temperature of the outer shroud via a thermal medium. A bucket tip clearance control system forms part of a turbomachinery apparatus including a casing, an outer shroud coupled with the casing, and an inner shroud coupled with the outer shroud. The tip clearance control system includes a flow circuit for a thermal medium defining a flow path within the outer shroud. A thermal medium source delivers the thermal medium to the flow circuit in a predefined condition according to operating parameters of the turbomachinery apparatus. The temperature of the outer shroud is controlled according to the predefined condition of the thermal medium. By accurately controlling the temperature of the outer shroud, bucket tip clearance can be controlled and optimized during all of the various operation stages of turbomachinery.