Optimized Approach for Determination of the Solid Temperature in a Steam Turbine in Warm-Keeping-Operation

International audienceThe determination of the temperature distribution in the thick-walled components in steam turbines is increasing in relevance. Due to the growing share of volatile renewable power generation, power plants with a high flexibility and a high integral efficiency are required. e current operational conditions lead to high thermal stresses inside the heavy components and thus to a reduced lifetime. To improve the ability for a fast start-up, the steam turbine can be kept warm during a longer period of stand still. Therefore, information about the metal temperature inside the rotor and the casing are crucial. However, the temperature distribution of the inner casing and especially the rotor cannot be measured without high additional effort. us, a calculation model with sufficient accuracy and also manageable calculation effort is required. In the present work, a hybrid-numerical FEM and analytical-approach has been developed to calculate the solid body temperatures of a steam turbine in warm-keeping operation in a most efficient way. The presented model provides accuracy of nearly % compared with Conjugate-Heat-Transfer simulations with a simultaneously reduced calculation effort by a factor of more than

Test Rig for Applied Experimental Investigations of the Thermal Contact Resistance at the Blade-Rotor-Connection in a Steam Turbine

International audienceStudies have shown that in a pre-warming respectively warm-keeping operation of a steam turbine, the blades and vanes transport most of the heat to the thick-walled casing and rotor. Thereby, a bottle-neck arises at the connection between the blade root and the rotor. The contact heat resistance at these interfaces affects the temperature distribution and thus the thermal stresses in the rotor. The present paper introduces a thermal contact resistance test rig, which is designed to quantify the contact heat transfer at the blade-rotor-connection of a steam turbine. An uncertainty analysis is presented which proves that the average measurement uncertainties are less than one percent. In addition to the test rig, a numerical model of the specimen for the determination of the thermal contact resistance is developed and introduced. Results of several steady-state measurements under atmospheric and evacuated atmosphere using a highly temperature-resistant chromium molybdenum steel are shown. As a main influence parameter the contact pressure is investigated, which is affected by the rotational speed of the turbine. The investigations show a significant contact heat resistance especially at small contact pressures

Preliminary evaluation of mutagenic activity of two amino derivatives of cyclopenta[c]phenanthrene

The mutagenicity of two, newly synthesized amino-derivatives of cyclopenta[c]phenanthrene (CP[c]Ph) was investigated in the Ames test using TA98 and TA100 histidine dependent Salmonella typhimurium strains. Neither of the examined compounds showed mutagenic activity without metabolic activation. The incorporation of an activation system caused high mutagenicity of CP[c]Ph derivatives in both S. typhimurium strains. The results are compared with the previous data on the mutagenic activity of unsubstituted CP[c]Ph and possible mechanisms of activation are discussed