Double-flow steam turbines

摘要

The reheat tub (T) in a double-flow steam turbine is provided with additional setback from the rotor buckets (38) by forming a three-part reheat tub construction including first and second discrete diaphragm segments (26,28) and third inner ring segments (36). The annular arrays of these segments are dimensioned to enable greater axial spacing between the nozzles (34) and buckets (38). To refurbish an in-service double-flow turbine, the damaged reheat tub is removed and cut along axial and radial part lines to form discrete first and second diaphragm segments. The diaphragm segment nozzles are then refurbished by adding weld material and machined to the appropriate configuration. Material is added to the downstream and removed from the upstream faces of each diaphragm so that it may be located in the turbine shell similarly as the removed tub, but with the nozzles spaced further axially upstream of the buckets.