Toshiba last stage blade (LSB) retrofits in low pressure steam turbines typically result in better performance, requiring fewer inspections and less maintenance, and improving operational flexibility. Using modern airfoil designs, a variety of LSB lengths ranging from 26 to 40 inches are operational in both Toshiba and General Electric machines. Decades of experience with its worldwide fleet has given Toshiba the knowledge base to develop these high-performance, high-reliability last stage blades. A summary of key technical advantages includes:
In addition to L-0 blade retrofits, Toshiba has developed and applied "long shank" L-1 LP turbine blade modifications. Our long shank blade solution allows for reuse of turbine rotors where there is evidence of significant dovetail cracking. The modification involves removing the existing dovetail and re-machining a new dovetail in material below the original dovetail height. The design also allows for lower stresses of the dovetail hooks, with analyses revealing a typical 15% stress reduction in the long shank design.