Steam of generator esp. for high temp. gas cooled reactor - has vertical straight reheater tubes surrounding vertical superheater tubes

摘要

A steam generator for a gas-cooled nuclear reactor is housed in a lined vault of the pressure vessel and comprises heat exchange surfaces consisting of preheater (economiser), evaporator, superheater and intermediate superheater (reheater) sections. The prheater, evaporator and =1 superheating zone are formed of helical tube bundles in an outer annulus, while the final superheater zone comprises a vertical, straight tube bundle in the 'core' region of the steam generator within the helix. The gas inlet is in the side of the steam generator. The reheater section is also composed of vertical, straight tubes occupying the annular space below the helix and around the downward projecting final superheater tubes where they extend below the helix. The upper region of these reheater tubes is at the same level as the gas inlet and is encased between an inner cylindrical guide plate or jacket and an outer jacket. The annular space between this outer jacket and the vault liner has a lower boundary composed of an annular (conical) wall and a gap seal extending around the entire circumference, while the upper end of the annular space is bounded by a second gap seal and a curved deflector plate for the incoming coolant gas. Inside the intermediate superheater (reheater) there is a curved bottom deflector plate which guides the hot incoming coolant gas from the reheater into the final superheater in the centre of the vessel. The gas flow around the reheater is improved and a considerable reduction in thermal stresses.