Which device is utilized to develop a vacuum during the startup of a condensing turbine?

The air ejector is utilized to develop a vacuum during the startup of a condensing turbine because its primary function is to remove non-condensable gases from the condenser. Creating a vacuum in the condenser is critical for optimizing the thermal efficiency of the turbine. By effectively lowering the pressure within the condenser, the air ejector enhances the condensation of steam, which aids in improving the overall performance of the condensing turbine.

When the condensing turbine starts, it is essential to ensure that the condenser operates at a sufficiently low pressure, allowing steam to condense efficiently. The air ejector helps accomplish this by removing air and other gases that may have accumulated, thus facilitating the creation of the necessary vacuum. This improved vacuum translates to better steam flow and greater efficiency during turbine operations.

In contrast, the other options serve different purposes. The condensing turbine itself is the system being operated, the hydraulic governor is involved in controlling the turbine's speed and load, while the thrust bearing supports the axial load generated by the turbine's rotor. None of these components specifically address the vacuum development needed in the condenser during startup, which is why the air ejector is the correct choice.