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    Wyświetlanie 1-9 z 9
    Tytuł:
    The influence of external cooling system on the performance of supercritical steam turbine cycles
    Autorzy:
    Kosman, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/240233.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    para nadkrytyczna
    schładzanie
    turbina parowa
    wydajność
    cooling
    efficiency
    steam turbine
    supercritical steam
    Opis:
    The problem presented in this paper refers to the concepts applied to the design of supercritical steam turbines. The issue under the investigation is the presence of a cooling system. Cooling systems aim to protect the main components of the turbines against overheating. However the cooling flows mix with the main flow and modify the expansion line in the steam path. This affects the expansion process in the turbine and changes the performance when compared to the uncooled turbine. The analysis described here investigates the range of the influence of the cooling system on the turbine cycle. This influence is measured mainly through the change of the power generation efficiency. The paper explains the approach towards the assessment of the cooling effects and presents results of the modeling for three supercritical steam cycles.
    Źródło:
    Archives of Thermodynamics; 2010, 31, 3; 131-144
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A new method for optimum heating of pressure components in supercritical steam power blocks
    Autorzy:
    Rząsa, D.
    Duda, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/240145.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    kotły parowe
    metody optymalizacji
    wymiana ciepła
    heat transfer
    optimization methods
    steam boilers
    total stresses
    Opis:
    One of the major concerns of the power energy industries is a proper operation of steam power blocks. Pressurized working medium and high temperature cause very high stresses in the construction elements such as collectors, separators or steam valves. They are exposed to sudden temperature and pressure changes that cause high stresses at certain points. Additionally, the cyclic character of loading causes material fatigue, known as low-cyclic fatigue, which may lead to the formation of fracture. Thus, methodologies offered by many companies should ensure reliable and safe operation of steam power blocks. The advanced numerical solutions for determining time-optimum medium temperature changes are presented. They are based on Levenberg-Marquardt and nonlinear programming by quadratic Lagrangian methods. The methods allow us to find parameters for start-up and shut-down operation that can reduce total stresses to limits governed by European regulations. Furthermore, the heating and cooling operations are conducted in a shortest time possible.
    Źródło:
    Archives of Thermodynamics; 2012, 33, 3; 133-145
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modelling of heat and flow phenomena occuring in waterwall tubes of boilers for supercritical steam parameters
    Autorzy:
    Zima, W.
    Grądziel, S.
    Cebula, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/240331.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    ekran wodny
    model matematyczny
    parametry nadkrytyczne
    parametry rozłożone
    schemat różnicowy
    distributed parameters
    Implicit difference scheme
    mathematical model
    supercritical parameters
    waterwalls
    Opis:
    In this paper a mathematical model enabling the analysis of the heat-flow phenomena occurring in the waterwalls of the combustion chambers of the boilers for supercritical parameters is proposed. It is a one-dimensional model with distributed parameters based on the solution of equations describing the conservation laws of mass, momentum, and energy. The purpose of the numerical calculations is to determine the distributions of the fluid enthalpy and the temperature of the waterwall pipes. This temperature should not exceed the calculation temperature for particular category of steel. The derived differential equations are solved using two methods: with the use of the implicit difference scheme, in which the mesh with regular nodes was applied, and using the Runge-Kutta method. The temperature distribution of the waterwall pipes is determined using the CFD. All thermophysical properties of the fluid and waterwall pipes are computed in real-time. The time-spatial heat transfer coefficient distribution is also computed in the on-line mode. The heat calculations for the combustion chamber are carried out with the use of the zone method, thus the thermal load distribution of the waterwalls is known. The time needed for the computations is of great importance when taking into consideration calculations carried out in the on-line mode. A correctly solved one-dimensional model ensures the appropriately short computational time.
    Źródło:
    Archives of Thermodynamics; 2010, 31, 3; 19-31
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Feasibility study of forced cooling of a supercritical steam turbine after a shut down of a power generating unit
    Autorzy:
    Kosman, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/240243.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    optymalizacja
    proces przejściowy
    turbina parowa
    optimization
    stresses
    supercritical steam turbine
    transient process
    Opis:
    Temperature related decrease of steam turbine components is one of the main transient processes that occur during a typical long-term operation. With a natural cooling (no user interference) it takes more than 14 days before the temperature of components reaches the level that allows to open and repair a turbine. It is then reasonable to apply a forced cooling in order to decrease the time between a shut-down of a power generating unit and a beginning of a repair. This paper presents the analysis of application of a forced cooling process to supercritical steam turbines. The main problems under the investigation are the safety issues of the process and the optimization of cooling conditions. The paper describes the safety restrictions and the optimization criteria. The process is analyzed in numerical simulations conducted for various cooling conditions.
    Źródło:
    Archives of Thermodynamics; 2011, 32, 3; 201-214
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Selection of the rotor heat-up rate for supercritical parameter turbines
    Autorzy:
    Rusin, A.
    Lipka, M.
    Łukowicz, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/240710.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    steam turbines
    steel for ultra-supercritical steam unit
    unsteady states
    turbiny parowe
    stal
    jednostka ultra-nadkrytyczna
    warunki niestabilne
    Opis:
    The paper presents the results of the numerical analyses for the steam turbine rotor, dedicated for the newly-designed 900 MW steam unit with supercritical steam parameters (650°C, 30.0 MPa). Basing on the design calculations, an optimal design solution was determined. Review of the available literature on materials for turbine rotors with supercritical steam parameters was done. Then the start-ups of the turbine were simulated. Thermal and strength states were analyzed. As a result, an optimal start-up characteristic was obtained.
    Źródło:
    Archives of Thermodynamics; 2013, 34, 3; 89-104
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermodynamic and economic analysis of a 900 MW ultra-supercritical power unit
    Autorzy:
    Łukowicz, H.
    Dykas, S.
    Rulik, S.
    Stępczyńska, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/240644.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    obieg pary
    parametry apry
    podwójne podgrzewanie
    coal-fired power unit
    double reheat
    steam cycle
    ultra-supercritical steam parameters
    Opis:
    The paper presents a thermal-economic analysis of different variants of a hard coal-fired 900 MW ultra-supercritical power unit. The aim of the study was to determine the effect of the parameters of live and reheated steam on the basic thermodynamic and economic indices of the thermal cycle. The subject of the study was the cycle configuration proposed as the "initial thermal cycle structure" during the completion of the project "Advanced Technologies for Energy Generation" with the live and reheated steam parameters of 650/670 [degrees]C. At the same time, a new concept of a thermal cycle for ultra-supercritical parameters with live and reheated steam temperature of 700/720 [degrees]C was suggested. The analysis of the ultra-supercritical unit concerned a variant with a single and double steam reheat. All solutions presented in the paper were subject to a detailed thermodynamic analysis, as well as an economic one which also included CO2 emissions charges. The conducted economic analysis made it possible to determine the maximum value of investment expenditures at which given solutions are pro.table.
    Źródło:
    Archives of Thermodynamics; 2011, 32, 3; 231-245
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Control-volume-based model of the steam-water injector flow
    Autorzy:
    Kwidziński, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/240854.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    kondensacja
    nadkrytyczny dozownik wodno-gazowy
    nierównowaga termiczna
    równanie bilansowe
    straty nieodwracalne
    balance equations
    condensation
    irreversible losses
    supercritical steam-water injector
    thermodynamic nonequilibrium
    Opis:
    The paper presents equations of a mathematical model to calculate flow parameters in characteristic cross-sections in the steam-water injector. In the model, component parts of the injector (steam nozzle, water nozzle, mixing chamber, condensation wave region, diffuser) are treated as a series of connected control volumes. At first, equations for the steam nozzle and water nozzle are written and solved for known flow parameters at the injector inlet. Next, the flow properties in two-phase flow comprising mixing chamber and condensation wave region are determined from mass, momentum and energy balance equations. Then, water compression in diffuser is taken into account to evaluate the flow parameters at the injector outlet. Irreversible losses due to friction, condensation and shock wave formation are taken into account for the flow in the steam nozzle. In two-phase flow domain, thermal and mechanical nonequilibrium between vapour and liquid is modelled. For diffuser, frictional pressure loss is considered. Comparison of the model predictions with experimental data shows good agreement, with an error not exceeding 15% for discharge (outlet) pressure and 1 K for outlet temperature.
    Źródło:
    Archives of Thermodynamics; 2010, 31, 1; 45-59
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Validation of a program for supercritical power plant calculations
    Autorzy:
    Kotowicz, J.
    Łukowicz, H.
    Bartela, Ł.
    Michalski, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/240731.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    blok nadkrytyczny
    cykl parowy
    walidacja
    steam cycle
    supercritical power plant
    validation
    Opis:
    This article describes the validation of a supercritical steam cycle. The cycle model was created with the commercial program GateCycle and validated using in-house code of the Institute of Power Engineering and Turbomachinery. The Institute's in-house code has been used extensively for industrial power plants calculations with good results. In the first step of the validation process, assumptions were made about the live steam temperature and pressure, net power, characteristic quantities for high- and low-pressure regenerative heat exchangers and pressure losses in heat exchangers. These assumptions were then used to develop a steam cycle model in GateCycle and a model based on the code developed in-house at the Institute of Power Engineering and Turbomachinery. Properties, such as thermodynamic parameters at characteristic points of the steam cycle, net power values and efficiencies, heat provided to the steam cycle and heat taken from the steam cycle, were compared. The last step of the analysis was calculation of relative errors of compared values. The method used for relative error calculations is presented in the paper. The assigned relative errors are very slight, generally not exceeding 0.1%. Based on our analysis, it can be concluded that using the GateCycle software for calculations of supercritical power plants is possible.
    Źródło:
    Archives of Thermodynamics; 2011, 32, 4; 81-89
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A new method for determining allowable medium temperature during transient operation of thick-walled elements in a supercritical power plant
    Autorzy:
    Duda, P.
    Rząsa, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/240343.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    kocioł parowy
    naprężenia całkowite
    optymalizacja
    wymiana ciepła
    heat transfer
    optimization
    steam boilers
    total stresses
    Opis:
    Construction elements of supercritical power plants are subjected to high working pressures and high temperatures while operating. Under these conditions high stresses in the construction are created. In order to operate safely, it is important to monitor stresses, especially during start-up and shut-down processes. The maximum stresses in the construction elements should not exceed the allowable stress limit. The goal is to find optimum operating parameters that can assure safe heating and cooling processes [1-5]. The optimum parameters should guarantee that the allowable stresses are not exceeded and the entire process is conducted in the shortest time. In this work new numerical method for determining optimum working parameters is presented. Based on these parameters heating operations were conducted. Stresses were monitored during the entire processes. The results obtained were compared with the German boiler regulations - Technische Regeln fur Dampfkessel 301.
    Źródło:
    Archives of Thermodynamics; 2010, 31, 3; 55-72
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

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