Improving the power unit operation flexibility by the turbine start-up optimization

Nowak, Grzegorz; Rusin, Andrzej; Łukowicz, H.; Tomala, Martyna

doi:10.1016/j.energy.2020.117303

Cited by 19 publications

(5 citation statements)

References 21 publications

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“…The maximum stress value occurs in the central bore and may cause propagation of cracks located there. The details concerning computer simulations of the rotor thermal and strength states in different phases of the turbine start-up are presented in [15]. To calculate the crack propagation rate under creep conditions, it is necessary to know the values of creep-related equivalent (von Mises) stress.…”

Section: Crack Propagation In the Turbine Rotormentioning

confidence: 99%

“…These activities include changes in the method of operation [13,14], repair of a damaged element or element replacement. The possibilities of improving the flexibility of the power unit operation by optimizing the turbine start-up procedure to substantially shorten the start-up time are described in [15]. The thermal and strength analysis of the turbine high pressure (HP) part was performed using the finite element method (FEM).…”

Section: Introductionmentioning

confidence: 99%

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Risk-Based Planning of Diagnostic Testing of Turbines Operating with Increased Flexibility

2020

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An increase in the share of renewable sources in the energy mix makes coal-fired power plants operate in new conditions that require more dynamic operation and adequate flexibility. The frequency of the power unit start-ups increases and so does the frequency of changes in loads. This intensifies some life consumption processes, such as low-cycle fatigue and crack propagation in the turbine components. Further operation of power unit elements that have already been in service for a long time has to be supplemented with new diagnostic and repair procedures that take into account the intensification of life consumption processes. This article gives predictions about the propagation rate of potential cracks in the turbine rotor for different scenarios of the power unit’s long-term operation. A method is presented of rational selection of the diagnostic testing time based on risk analysis. The method is used to estimate the optimal interval after which diagnostic testing of a 200 MW turbine rotor should be carried out. Changes in the rotor steel crack toughness are evaluated based on the results of testing of microspecimens cut out of the rotor. Turbines with more frequent start-ups and shorter start-up times necessitate performance of diagnostic testing of the rotor central bore after about 12 years of turbine operation.

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Section: Crack Propagation In the Turbine Rotormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Risk-Based Planning of Diagnostic Testing of Turbines Operating with Increased Flexibility

2020

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“…of Power System Engineering, Faculty of Mechanical Engineering, University of West Bohemia, Czech Republic 2 Experimental Research of Flow, Doosan Skoda Power, Czech Republic * E-mail: petreret@kke.zcu.cz https://doi.org/10.36897/jme/150830 contributor to the future power supply mix in various countries to meet the energy demand [6][7][8][9][10]. In synergy with the wind and solar energy sources, coal-fired steam power plants must operate flexibly based on market demand [11][12][13][14][15][16][17] and supply electric power with the highest efficiency and the lowest emissions possible. One feasible way to meet the high-efficiency requirements is an optimised turbine steam path with minimal aerodynamic and leakage losses in rotating and stationary components.…”

Section: Introductionmentioning

confidence: 99%

Effect of Manufacturing Processes on Blade Throat Size and Position in a Steam Turbine Diaphragm

Eret¹,

Hoznedl²

2022

Journal of Machine Engineering

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Despite a sustainable energy future, steam turbines are requisite for the reliability and security of the electric power supply in many countries. Accurate and precise manufacturing of the steam path is crucial to turbine efficiency. Before entering the rotor blades, the steam must be correctly guided using stationary blading in a diaphragm. Steam turbine diaphragms are complicated components to manufacture, and welding is the most common fabrication method. A case study presented in this paper employs data from a 3D optical scanner for a geometric deviation analysis of the upper half of the diaphragm at two production steps, after complete welding and after final machining. Unrolled cylinder cross-sections at different diameters are used to evaluate the blade throat sizes and positions compared to the nominal geometry. The results indicate significant geometric changes between the two fabrication steps, and several suggestions are put forward for targeted future work.

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“…Steam turbines are subject to severe operating conditions [5,6], and rotor last stage blades can operate in a compressor mode delivering energy to the working fluid in low volume flow conditions [7]. Concepts of a dynamic power plant and solutions for an operational flexibility enhancement appear more often in the literature [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Geometric Errors of Throat Sizes of Last Stage Blades in a Mid-Size Steam Turbine

Eret¹,

Hoznedl²

2022

Journal of Machine Engineering

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Steam turbine technology with enhanced flexibility will continue to participate in electric power supply mixes. Last stage blades secure the reliability of a steam turbine and require high precision manufacturing and assembly. This case study presents a statistical analysis of geometric errors of the throat sizes of the last stage blades in a mid-size steam turbine. A 3D optical scanner is employed to capture detailed geometries of rotor blades and a half of assembled nozzle diaphragm. Unrolled cylinder cross-sections are used to evaluate 2D geometrical features such as blade throats and areas at three different diameters, and the results are compared to intended designs. In addition, linear correlations between the throat size and blade pitch, area and trailing edge thickness are established, and blade throat position shifts are quantified. Such a comprehensive study is presented for the first time, and some useful conclusions can be retrieved from this case study.

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Improving the power unit operation flexibility by the turbine start-up optimization

Cited by 19 publications

References 21 publications

Risk-Based Planning of Diagnostic Testing of Turbines Operating with Increased Flexibility

Risk-Based Planning of Diagnostic Testing of Turbines Operating with Increased Flexibility

Effect of Manufacturing Processes on Blade Throat Size and Position in a Steam Turbine Diaphragm

Analysis of Geometric Errors of Throat Sizes of Last Stage Blades in a Mid-Size Steam Turbine

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