Steam turbine casing axial thermal expansion is of great significance to the safe operation for nuclear units.
Taking a certain 1000MW nuclear steam turbine’s HIP casing as an object, this paper calculates the HIP casing absolute axial thermal expansions under such conditions as: steady-state, startup and load shedding.
Firstly, a 3D model of the nuclear steam turbine HIP casing is this established by using Pro/E software. Secondly, the heat transfer coefficients of every surface of HIP casing are calculated. Finally, the HIP casing temperature field and the absolute axial thermal expansions under three conditions are calculated and analyzed by using finite element analysis software.
The result shows that, the HIP casing axial thermal expansions are 22.642mm and 22.529mm under steady-state condition and startup condition respectively. While, under load shedding condition, minimum axial expansion is 16.202mm and it increases to 22.491mm at rated load.