Increasing the efficiency of steam turbines which have been in operation for many years

Abstract

Different designs of modification of flow range in long-lived turbine plants have been considered in the presented paper. The maximum turbine power increment can be achieved by modernization of a turbine blading system. The use of blades with various nozzle-exit angles ɑand meridional profiling for short blades of the first stages in high-pressure section provides an opportunity to increase efficiency by 2÷3% in comparison with a reference power. A significant gain in performance is associated with the design improvement of seals. Modern designs of seals make it possible to decrease steam leakage by 10÷30 % that results in an increase in turbine efficiency. Maximum aerodynamic efficiency of flow channels with adverse pressure gradient has been achieved under a stable unseparated flow. The same holds for diffuser steam-turbine exhausts of the HP (high-pressure) part, the LP (low-pressure) part and the IP (intermediate pressure) part, and also diffusers of control valves. The research and the first effort of research in modification suggest possible increment of a turbine power up to 10÷12 % in comparison with a reference power. This result can be obtained only due to modification of the blade system without changing the component of a turbine casing. The discussed engineering proposals can be implemented major overhaul of the steam turbine even in power plant conditions