IMPROVED LP-STAGE DESIGN FOR INDUSTRIAL STEAM TURBINES

This publication deals with the improvement of the design and life steam testing of a low-pressure steam turbine module for utilization in industrial applications. Extensive numerical investigations were carried out and validated with experimental measurements. For the validation of the final blade design, the LP module was integrated and tested in a 12.5MW steam turbine test rig. During the balancing of the rotor in a vacuum chamber, tip-timing and strain gage measurements were conducted for testing the mechanical behavior of the airfoils. In the succeeding assembly of the steam turbine, tip-timing probes and flow measurement probes were integrated around the LP module to evaluate the blade load and performance under realistic conditions. To obtain a good understanding of the improved performance and mechanical behavior the thermodynamic tests were carried out under no-load, part load and design load conditions to cover the whole operating range of the LP stages. The paper also describes how an existing rotor from the test rig could be retrofitted, to accommodate the new turbine stages with additive manufacturing of the base material on the shaft.