Wyniki wyszukiwania - BazTech

1

Advanced lifetime assessment of steam turbine components based on long-term operating data

Banaszkiewicz M., Radulski W., Dominiczak K.

Archive of Mechanical Engineering

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2018

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Vol. LXV, nr 4

579--597

EN

The paper presents a new method of lifetime calculations of steam turbine components operating at high temperatures. Component life is assessed on the basis of creep-fatigue damage calculated using long-term operating data covering the whole operating period instead of representative events only. The data are analysed automatically by a dedicated computer program developed to handle big amount of process data. Lifetime calculations are based on temperature and stress analyses performed by means of finite element method and using automatically generated input files with thermal and mechanical boundary conditions. The advanced lifetime assessment method is illustrated by an example of lifetime calculations of a steam turbine rotor.

2

A verification approach to thermoelastic steam turbine rotor analysis during transient operation

Dominiczak K., Banaszkiewicz M.

Transactions of the Institute of Fluid-Flow Machinery

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2016

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nr 131

55--65

EN

This paper presents a verification approach to thermoelastic steam turbine rotor analysis. Neither temperature nor stresses are measured on the rotor surface in utility power plants. Therefore analysis of the steam turbine rotor can be verified only based on absolute and differential thermal expansion measurements in vicinity of the steam turbine. Absolute and differential expansion measurements and steam turbine fixed points arrangement allow to calculate thermal growth of the steam turbine rotor during transients. Thermal growth of the rotor can be a baseline for the calculation using a numerical model.

3

A methodology for online rotor stress monitoring using equivalent Green’s function and steam temperature model

Banaszkiewicz M., Dominiczak K.

Transactions of the Institute of Fluid-Flow Machinery

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2016

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nr 133

13--37

EN

The requirement of high operational ﬂexibility of utility power plants creates a need of using online systems for monitoring and control of damage of critical components, e.g., steam turbine rotors. Such systems make use of diﬀerent measurements and mathematical models enabling calculation of thermal stresses and their continuous control. The paper presents key elements of the proposed system and discusses their use from the point of view of thermodynamics and heat transfer. Thermodynamic relationships, well proven in design calculations, were applied to calculate online the steam temperature at critical locations using standard turbine measurements as input signals. The model predictions were compared with operational data from a real power plant during a warm start-up and show reasonably good accuracy. The eﬀect of variable heat transfer coeﬃcient and material properties on thermal stresses was investigated numerically by ﬁnite element method (FEM) on a cylinder model, and a concept of equivalent Green’s function was introduced to account for this variability in thermal stress model based on Duhamel’s integral. This approach was shown to produce accurate results for more complicated geometries by comparing thermal stresses at rotor blade groove computed using FEM and Duhamel’s integral.

4

Thermal stress limiter for 13K215 steam turbine retrofit in Połaniec Power Plant, Poland

Dominiczak K., Radulski W., Banaszkiewicz M., Mróz K., Bondyra R.

Journal of Power Technologies

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2016

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Vol. 96, nr 4

285--294

EN

This paper studies the functioning of a thermal stress limiter for a 13K215 steam turbine in Połaniec Power Plant, which is a typical example of a 200 MW steam turbine retrofit. The share of renewable energy sources in the energy market is growing, leading to an increased demand for flexibility in conventional units, i.e., fast loading, fast unloading and fast start up etc. Thermal stress in steam turbine thick-walled elements, the steam turbine rotor in particular, is a major limit on the flexible operation of steam turbines. Therefore, steam turbine are usually controlled and protected by on-line stress control, i.e., a thermal stress limiter. In steam turbine retrofits in Połaniec Power Plant, each steam turbine was delivered by Alstom together with a thermal stress limiter implemented on a stand-alone PLC (Programmable Logic Controller). The thermal stress limiter for 13K215 steam turbine retrofits protects HP and IP rotors as well as HP and IP valve chests. The thermal stress limiter ensures safe operation of the steam turbine for the operating period required by the steam turbine owner. The thermal stress limiter also ensures the shortest possible steam turbine start up time for a guaranteed number of startups.

5

Pod czujnym okiem. Rola nowoczesnego systemu monitoringu w zarządzaniu i optymalizacji żywotności turbin

Bzymek G., Banaszkiewicz M., Radulski W., Dominiczak K.

Energetyka Cieplna i Zawodowa

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2016

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Nr 6

72--78

PL

Wprowadzenie nowych technologii nadzoru turbiny/bloku w urządzeniach wyprodukowanych w poprzednim wieku pozwala dzisiaj nadążać za wzrastającymi wymaganiami KSE.

6

Steam turbine stress control using NARX neural network

Dominiczak K., Rządkowski R., Radulski W.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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2014

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nr 145

37--38

EN

Considered here is concept of steam turbine stress control, which is based on Nonlinear AutoRegressive neural networks with eXogenous inputs. Using NARX neural networks, which were trained based on experimentally validated FE model allows to control stresses in protected thick-walled steam turbine element with FE model quality. Additionally NARX neural network, which were trained base on FE model, includes: nonlinearity of steam expansion in turbine steam path during transients, nonlinearity of heat exchange inside the turbine during transients and nonlinearity of material properties during transients. Moreover NARX neural network allows to predict strength parameters (stress and temperature in protected steam turbine thick-walled element) for few time steps ahead. This leads to high accuracy of stress control. In this article NARX neural networks stress controls is shown as an example of HP rotor of 18K390 turbine. HP part thermodynamic model as well as heat exchange model in vicinity of HP rotor, which were used in FE model of the HP rotor and the HP rotor FE model itself were validated bas on experimental data for real turbine transient events. In such a way it is ensured that NARX neural network behave as real HP rotor during steam turbine transient events.