Apparatus and methods for expanding a process fluid are disclosed. The apparatus includes a casing having an inlet and an outlet, and a component carrier disposed in the casing. The component carrier and the casing defining a cavity therebetween, and the component carrier at least partially defines a process flowpath fluidly communicating with the inlet and the outlet of the casing. The apparatus also includes a rotor disposed at least partially in the component carrier, with the rotor at least partially defining a first expansion stage intersecting the process flowpath. The apparatus also includes a bleed port extending from the process flowpath at a first point of the process flowpath to the cavity, to provide a thermal buffer fluid to the cavity.