Expansion Line Modeling and Strength Diagnostics of Internally Cooled Gas Turbines

Abstract

This paper regards control and optimization of a gas turbine operation with a respect to effectiveness and reliability criteria. The development of diagnostics procedures begins with modeling of the gas expansion line for various loads with regard to an internal blade cooling. Analyzing an expansion line allows to assess the influence of cooling parameters on gas path and turbine operation. Computational models are described here, which respect various cooling aspects, mainly convection and film cooling. Several examples of gas path, blade temperature and thermal barrier coating (TBC) temperature dependencies on cooling parameters are presented. The determination of gas and metal temperatures is utilized to evaluate creep wear rate. The dependency between the strength and durability of turbine components and their temperature might be regarded in several aspects. Firstly: lower temperature decreases the creep rate. Even small temperature drop leads to a significant deceleration of creep processes. Secondly: the change of the temperatures modifies also the distribution of thermal stresses. This change of thermal stresses is usually very small and might be neglected. Presented analysis omits the influence of temperatures alteration of stresses distribution, it regards however the change of the creep characteristics.

The influence of external cooling system on the performance of supercritical steam turbine cycles

“…However in the assessment of the cycle performance the most important aspect is the influence of the coolant on the main flow. This problem has been discussed for example in [6] and [7]. The results of the analysis given in those references proved that the major impact on the expansion line results form the mixing between the cooling and the main flow.…”

Simulation modules of thermal processes for performance control of CHP plant with a gas turbine unit

“…In case of the second category, when the cooling is not too intensive, simplifying assumptions might be made. The cooling air mixes with the main stream at [1], while line ''b'' corresponds to the model described in [2].…”

“…This approach is not always sufficient. An additional information is required for more adequate assessment of the performance [1][2][3][4][5][6]. Therefore a simulation module should be added to the control system.…”

Thermal elongations in steam turbines with welded rotors made of advanced materials at supercritical steam parameters

“…The rotor and casing model is assumed to be a structure of revolution under axisymmetrical load. The displacements of each point of the deformed component (rotor or casing), which are in a cylindrical coordinate system (r, z, ) and are related to the initial configuration (assembly, cold state) are described by the displacement vector, u, [18]:…”

“…The developed model involves the algorithms and numerical codes described in [18], which calculate the steam parameters at the outlets in consecutive stages. The input data for the calculations consists of the steam flow, the pressure and the temperature (m s,0 ,T s,0 , p s,0 ) at the turbine inlet.…”