Calculated and Experimental Substantiation of Increasing the Interval between Repairs of the SGT5-2000E Gas Turbine Cooled Blades

Abstract

The article presents substantiation of the possibility to extend the operation of the SGT5-2000E series gas turbine units beyond the period specified by the manufacturer after which the “hot” parts and, primarily, the cooled nozzle vanes and rotor blades of the turbine’s first stages should be replaced. Each gas turbine unit is provided, along with the operation manual, with a maintenance program proceeding from the assigned fleet service life, in accordance with which the time of operation with one set of cooled blades of the turbine’s first stages is determined. A gas turbine cannot operate reliably unless its worn “hot parts” are checked and, if necessary, are subjected to restorative repair. As a rule, this can be done in the course of appropriately long outages (e.g., minor inspections, overhauls, and hot gas path visual examinations). All time-dependent wear coefficients are calculated simultaneously, and the calculation result is expressed in equivalent hours of operation (equiv. h), which vary depending on the pattern and number of working cycles, operational mode, used fuel, and water injection availability. A service life reduction is determined and expressed as an equivalent number of operation at the base load. The total number of equivalent hours of operation is the sum of hours calculated under the specific operation conditions. The article presents scientifically substantiated recommendations for a limited extension of the interval between maintenances obtained from mathematical modeling of the wear processes of cooled nozzle vanes and rotor blades in the first stages, and from an analysis of a change in the longevity characteristics of the alloy they are made of.