SYSTEM DESIGN AND COOLING METHOD FOR LP STEAM TURBINES USING LAST STAGE HYBRID BUCKET

摘要

An axial steam turbine and a cooling method for low pressure steam turbines using a last stage hybrid bucket are provided to achieve improved design and efficiency of a hybrid blade. An axial steam turbine includes a rotor, a last stage, and at least one spray assembly. The last stage includes a diaphragm and buckets(24). The diaphragm includes an inner ring, an outer ring, and a plurality of nozzles extended between the inner ring and the outer ring. The buckets are fixed at the rotor in a lower stream of a last stage diaphragm such that the buckets are rotatable relatively to the diaphragm. The spray assembly sprays cooling medium at the last stage.