Wojciech Kosman

Analysis of cycle configurations for the modernization of combined heat and power plant by fitting a gas turbine system

The application of a gas turbine generally allows to increase the number of possible configurations of cogenerated heat and electrical power systems, which became a significant substitute for classic, coal-fired power plants. They are characterized by better thermodynamical, economical, ecological, and operating indexes. Gas turbine units are also the best option for the modernization of existing power plants. This paper discusses the effectiveness of various technological configurations with gas turbines, which are to be applied during modernization projects of already existing conventional combined heat and power plants. In the analysis enthalpy and entropy methods were applied. Algorithms of the entropy method allow to determine the entropy generation in each section of a combined heat and power (CHP) plant. Several criteria were taken into consideration while analyzing the effectiveness of technological cycle configurations with gas turbines. These include the energy effectiveness, the efficiency of the HRSG and the steam cycle, the efficiency of the whole thermal electric power station, the exergetic efficiency of the HRSG and the steam cycle, and the fuel efficiency index. It was assumed that gas turbines operate under their nominal conditions. The composite curves were also taken into consideration while choosing the type of the turbine. The modernization project tends not to eliminate those existing power plant sections (machines and equipment), which are able to operate further. The project suggests that those units should remain in the system, which satisfy the applied durability criterion. The last phase of the optimization project focuses on the sensibility verification of several steam-gas CHP plant parameters and their influence on the whole system.

Expansion Line Modeling and Strength Diagnostics of Internally Cooled Gas Turbines

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.Copyright

The Influence of Cooling Flows on the Operating Conditions of the Ultra-Supercritical Steam Turbine Components

This paper presents the results of the analysis on the heat transfer in the inlet section of an ultra-supercritical steam turbine. Such power generating units become the foundation of new coal-fired power plants. The monitoring of their operation is in many aspects similar to the traditional, sub-critical steam turbines. However, higher live and reheat steam parameters result in several key differences, which must be taken into the consideration when assessing the thermal and strength states of the turbines main components for the diagnostic supervision. One of the main differences is the presence of the cooling and designs specific for ultra-supercritical steam turbines, which aim to protect their components against overheating. The research described in this paper investigates the inlet section of the turbines, which is the area exposed to the highest thermal loads. The scope of the research includes both, numerical modeling and laboratory testing. A test stand has been built for the analysis of the flows in the inlet section. Cooling flows are under special attention here as their temperature field is coupled to the temperature fields of the turbine components (the rotor and the inner casing) due to the relatively small amount of the coolant. The paper provides detailed description of the test stand and some early measurement results, which involve the operation with cooling. Also the numerical modeling results are shown and compared to the measurement data.Copyright

Off-Design Operation of the Multi-Fuel CHP Cycles

The paper describes the problems when the operation regime of the CHP cycle is adjusted according to the user demands. The analysis concerns a multi-fuel system, which utilizes biomass, natural gas and coal. The analyzed system consists of a combined gas and steam cycles. The analysis presented here concerns off-design operation caused by part loading, varying ambient conditions and power demands. An appropriate division of the load between the sub-cycles increases the overall efficiency. The analysis concerns also various options of biomass supply to the system. The research regards mostly the effectiveness criterion as it has a direct influence on the costs of operation.Copyright

On-Line Performance Evaluation of CHP Plant With Cooled Gas Turbine Supported by Off-Line Analysis Results

This paper presents a methodology of diagnostic investigations for gas turbines. The key feature is that the analysis is carried out in two modes: off-line and on-line. The first mode is performed periodically. It involves detailed measurements. Values obtained from measurements create the input data for further analysis. Health state of a gas turbine is then evaluated. The evaluation bases on calculation of several health state parameters. The on-line diagnostic mode uses these parameters as a reference state. The usual lack of measurements available in the on-line investigations creates the need for additional input data for the analysis. Therefore diagnostic investigations are supported by the results from the off-line mode. One of the main problems to be solved in diagnostic analysis is the appropriate modeling of gas turbine operation. An approach presented here regards the operation in various conditions, meaning also off-design operation.Copyright

Analysis of Cycle Configurations for the Modernization of Combined Heat and Power Plant by Fitting a Gas Turbine System

The application of a gas turbine generally allows to increase the number of possible configurations of cogenerated heat and electrical power systems, which became a significant substitute for classic, coal-fired power plants. They are characterized by better thermodynamical, economical, ecological and operating indexes. Gas turbine units are also the best option for the moderinization of existing power plants. This paper discusses the effectiveness of various technological configurations with gas turbines, which are to be applied during modernization projects of already existing conventional combined heat and power plants. In the analysis and entropy methods were applied. Algorithms of the entropy method allow to determine the entropy generation in each section of a combined heat and power (CHP) plant. Several criteria were taken into consideration while analyzing the effectiveness of technological cycle configurations with gas turbines. These include the energy effectiveness, the efficiency of the HRSG and the steam cycle, the efficiency of the whole thermal electric power station, the exergetic efficiency of the HRSG and the steam cycle, and the fuel efficiency index. It was assumed that gas turbines operate under their nominal conditions. The composite curves were also taken into consideration while choosing the type of the turbine. The modernization project tends not to eliminate those exiqsting power plant sections (machines and equipment), which are able to operate further. The project suggests that those units should remain in the system, which satisfy the applied durability criterion. The last phase of the optimization project focuses on the sensibility verification of several steam-gas CHP plant parameters and their influence on the whole system.Copyright