STATE OF THE ART STEAM TURBINE AUTOMATION FOR OPTIMUM TRANSIENT OPERATION PERFORMANCE

ABSTRACT The growing share of renewable energies in the power industry coupled with increased deregulation has led to the need for additional operating flexibility of steam turbine units in both Combined Cycle and Steam Power Plants. Siemens steam turbine engineering and controls presently have several solutions to address various operating requirements: -Use of an automatic step program to perform startups allows operating comfort and repeatability. -3 start-up modes give the operator the flexibility to start quickly to meet demand or slowly to conserve turbine life. -Several options for lifetime management are available. These options range from a basic counter of equivalent operating hours to a detailed fatigue calculation. -Restarting capabilities have been improved to allow a faster response following a trip or shutdown. -In addition to control of speed, load and pressure, special control functions provide alternative work split modes during transient conditions. -Optimum steam temperatures are calculated by the steam turbine control system to achieve optimum startup performance. -Siemens steam turbines are also capable of load rejection to house load, some even to operation at full speed, no load. Several plants are already equipped with these solutions and have provided data showing they are operating with shorter start-up times and improved load rejection capabilities. Finally Siemens of course continues to pursue future development

Regression analysis of the results of examinations of students in probability theory

In this paper, is carried a study of the dependence of the results of tests with the help of linear and nonlinear regression analysis. As a result of an earlier statistical analysis with the same data, was found the relationship between them

Optimierung der Energienutzung bei der Aluminiumherstellung

Analysing the sustainability of the aluminium industry, energy input is an important indicator. Besides the use of energy resources, energy consumption has a negative impact on the ecology, e.g., emissions caused by energy conversion, as well as economic effects due to energy costs. In this paper, options for reducing the energy use during aluminium production are being analysed. Subsequently, different methods for rating the quality of energy are being applied. In order to calculate scenarios concerning potential energy reduction for the entire process, each stage was examined and analysed separately. Because of their relevance to the consumption of energy, the calculations focus on primary production, excluding bauxite production and all transports in general, on electricity supply for the electrolysis and on the recycling of aluminium in light weight packaging, to cite just one example of secondary production. Applying the best available technology in each stage of aluminium production, the specific primary energy demand can be reduced by some 20%. Different types of power plants using different energy carriers yield enormous differences in efficiency. Therefore, the variation of electricity supply for aluminium electrolysis can lead to even higher savings. Balancing only inputs of electricity and fossil fuels raising the recycling quota up to 85% is reasonable from the energy point of view. Considering material-bound energy contents, e.g., by organic ingredients results in an optimal quota of 70%. But even in this case, the primary energy demand of the total production is reduced by 28% compared to the current state of affairs, whereby the recycling quota lies at a mere 59%

Optimierung der Energienutzung bei der Aluminiumherstellung

Analysing the sustainability of the aluminium industry, energy input is an important indicator. Besides the use of energy resources, energy consumption has a negative impact on the ecology, e.g., emissions caused by energy conversion, as well as economic effects due to energy costs. In this paper, options for reducing the energy use during aluminium production are being analysed. Subsequently, different methods for rating the quality of energy are being applied. In order to calculate scenarios concerning potential energy reduction for the entire process, each stage was examined and analysed separately. Because of their relevance to the consumption of energy, the calculations focus on primary production, excluding bauxite production and all transports in general, on electricity supply for the electrolysis and on the recycling of aluminium in light weight packaging, to cite just one example of secondary production. Applying the best available technology in each stage of aluminium production, the specific primary energy demand can be reduced by some 20%. Different types of power plants using different energy carriers yield enormous differences in efficiency. Therefore, the variation of electricity supply for aluminium electrolysis can lead to even higher savings. Balancing only inputs of electricity and fossil fuels raising the recycling quota up to 85% is reasonable from the energy point of view. Considering material-bound energy contents, e.g., by organic ingredients results in an optimal quota of 70%. But even in this case, the primary energy demand of the total production is reduced by 28% compared to the current state of affairs, whereby the recycling quota lies at a mere 59%