Analysis of erosion hazards in turbines due to power units operating in low load conditions

Abstract

Coal fired power units are having to operate with higher operational flexibility due to changes in the structure of energy systems brought about by the increased production of electric energy from renewable sources. The flexibility at issue relates to frequent changes of generated power and long-running operation at minimum load. By operating in this mode coal fired power units compensate for the stochastic character of energy generated from renewable sources and ensure a desirable reliability level for energy systems, but at the same time it has various impacts on the durability and failure frequency of their component parts. One of the problems which can arise during the operation of turbines working at low loads is increased erosion of the last stage blades of the LP part. This paper presents an analysis of turbine operation conditions which may lead to increased erosion hazards for the blades of the LP part. We address the problem of temperature drop of the re-superheated steam during low load operation of the unit and investigate the impact of erosion losses on the change of dynamic state of the turbine’s last stage blades.