Bolesław AUGUSTYNIAK, Marek CHMIELEWSKI, Leszek PIOTROWSKI, Wojciech KIEŁCZYŃSKI, Karolina PROKOP, Dominik KUKLA
Internal stress level determination using Barhausen Effect probe with rotating magnetic field
The paper describes a novel procedure for the internal stress level determination, in industrial components, applying Barkhausen effect. The stress distribution is determined on the basis of analysis of angular distribution of Barkhausen effect intensity. Such distribution is determined automatically using a novel probe which generates rotating magnetic induction in the magnetized element. We present the principles of measurements, describe the experimental setup and give the examples of application of the method for the stress level assessment in the butt welded plates made of isotropic (grade S235) and anisotropic (grade M460) steels.
Keywords: tensions in steel welded joints, Barkhausen effect, evaluation of a steel tension condition
Ryszard BARTNIK, Zbigniew BURYN
Comparative thermodynamic and economic analysis of quasi-nonstationary operation of a power unit with the capacity of 370 MW in cogeneration used to feed network hot water with thermal parameters of 135/70°C and 110/70°C into district heating system
This paper presents selected results of comparative thermodynamic and economic analysis of quasi-nonstationary operation of a 370 MW power unit coupled with district heating system with the maximum thermal parameters of network hot water of 135/70°C and 110/70°C. For the capacities of the power unit of 180 MW and 380 MW, the following were derived: relations between ambient temperatures and the temperatures of the saturation of extraction steam, heat streams extracted into feed the heaters and the value of overall gross efficiency. The values of the production of electricity, use of the chemical energy of the fuel, production of heat in the heaters and mean annual efficiency were calculated for the annual operation of the power unit.
Keywords: 370 MW power unit, cogeneration work of a unit, heating networks
Ewelina BÖHM, Marta KUREK, Tadeusz ŁAGODA, Grzegorz JUNAK, Marek CIEŚLA
Fatigue damage accumulation of steel in uniaxial loading state and high temperature taking into account the strain history
The paper describes the influence of the asymptote c with the use of the Ebbinghause forgetting curve on the fatigue damage accumulation. A comparison of experimental results with numerical for the energy industry steels P91 and P92 with the model proposed by the authors has been done. After the comparison of the influence of the asymptote c on the damage accumulation according to the proposed model we can state, that the best results are given for the asymptote c=0.
Keywords: steel distortion accumulation, history of distortions, damage accumulation
Ihor DZIOBA, Robert PAŁA, Tadeusz PAŁA
Strength and Fracture Toughness of the ADI Ductile Iron
In the paper are presented the results of strength and fracture toughness the two modification of ADI ductile iron EN-GJS-1050-6. It was shown that insignificant changes into morphology of materials (size and dispersion) caused corresponding changes of material properties. Influence of fatigue loading on strength and fracture toughness ductile of the ADI ductile iron was also tested in the paper.
Keywords: ductile iron, castings strength, crack resistance
Mirosław GAJEWSKI, Piotr FURMAŃCZYK, Leopold BARWICKI
Corrosion fatigue cause of failure energy pipelines
The paper presents the mechanism of anodic dissolution of iron and the formation of cracks caused by corrosion fatigue. Discusses two typical cases of corrosion fatigue secondary steam pipe made of 10H2M steel and pipe nipple of boiler made of K18 type steel. The study confirmed the important role of galvanic cell in the process of cracking.
Keywords: power pipelines, pipeline corrosion, corrosion fatigue
Grzegorz GOLAŃSKI, Cezary KOLAN, Joanna JASAK, Jacek SŁANIA, Paweł URBAŃCZYK, Adam ZIELIŃSKI
Microstructure and properties of TP347HFG steel after long-term service
The paper presents the results of research on the microstructure and mechanical properties of austenitic high-temperature creep resisting TP347HFG (18Cr-12Ni-Nb) steel after around 105 000 hours of service. The steel subject to testing were serviced at the temperature of about 500 and 540°C. Mechanical properties of the examined steels after service were compared with the data taken from the manufacturer certificate of the pipes. The analysis of the microstructure of the investigated steel has shown that the precipitation of secondary carbides occurred during the service: NbC precipitated inside the grains and M23C6 on the boundaries of grains. More advanced precipitation processes on the boundaries of grains were observed in the steel serviced at higher temperature. Long-term service of TP347HFG steels had a slight influence on the change in their strength properties which were similar to the ones in the as-received state. Higher decrease was observed in the case of plasticity and ductility of the examined steels, and the degree of decrease in these properties depended on the temperature of service.
Keywords: long-term operation of a steel, steel mechanical properties after a long-term operation, plasticity reduction
Adam HERNAS, Grzegorz MOSKAL, Andrzej SENIUK
Analysis of a turbine environment corrosivity on the basis of sediments chemical compound
Results of investigations which are related to characterization of phase and chemical composition as well as morphology of deposits from low pressure turbine elements of 18K370 types from 5 different domestic power plant stations were presented in this article. There were significant differences related to chemical composition of deposits and presents of different elements such as Cu, Na, Cl and S. However in all analyzed cases the chemical composition of deposits levied form flow systems of investigated turbines and analysis of corrosivity of turbines environment don’t revealed that aggressive corrosive environment was presented during turbine work conditions as well as the advanced corrosion destruction was observed. Those facts are significant form continued exploitation of turbines.
Keywords: steam turbines, pitting corrosion, tension corrosion, standstill corrosion
Adam HERNAS, Krzysztof SZYMAŃSKI, Paweł WOLAŃCZYK, Bożena SZCZUCKA-LASOTA
Corrosion-erosion protection coattings on sealingwall of biomass boiler
The paper presents an analysis of the coatings, which after a few years has been catastrophic peeling in large patches, sprayed by a foreign company. The morphology investigation of the surface was carried out from the base material, and the exhaust side exfoliation coating. The results of microanalysis chemical composition and x-ray phase analysis allowed to identify the type of coating, which can be attributed to a (WC, CrC)- NiCr and propose their own urgent solution to the problem. In June 2014 on the biomass fired boiler are applied coatings, these coatings are selected on the basis of research conducted in research projects funded by NCBiR. It is obtained a two-layer coating consisting of materials: DRB-7 (Fe-Cr-B-Mo-Si-CW) sprayed by ARC method and CrC-NiCr sprayed by HVOF method, with a total thickness of max. 400 mm.
Keywords: biomass fired boilers, boiler wall corrosion, anti-corrosive protection
Stanisław KOZIOŁ, Andrzej ZBROWSKI
Idea of a machine for molding a ceramic anti-erosive layer in a pipeline for dust transport
The article presents the concept of a method and device for molding a ceramic anti-erosive layer in curvilinear elements of pipelines for the transport of dust. The issue particularly concerns the nodes of pipelines supplying power boilers with coal dust and discharging solid products of combustion. The concept involves the use of a mechanical system with active molding core for the application of a layer of a plastic, composite ceramic material onto the inner surface of the pipe section. The authors considered three different methods. They allow one to obtain an evenly distributed ceramic layer with the possibility to modify its geometry in order to optimize the shape, from the point of view of minimizing the flow resistance and providing high wear resistance. The concept is the initial stage of work aimed at the development of a model device that would allow experimental verification of the design and operating parameters of the molding system, and the evaluation of the applicability of this technology for mass production of piping elements fitted with a ceramic inner layer with specific thermal and tribological properties.
Keywords: pneumatic pipelines, dust transport, anti-corrosion layers
Mirosław ŁOMOZIK, Anna ZIELIŃSKA-LIPIEC, Krzysztof KWIECIŃSKI, Robert JACHYM
Microstructure of butt welds in PB2 steel pipes welded using conventional and temper bead technique
The object of research were butt joints of pipes of X13CrMoCoVNbNB9-2-1 (PB2) steel with an external diameter 219.1 mm and wall thickness 31 mm. Joints were welded using a conventional process, i.e. with post-weld heat treatment and without heat treatment, using the temper bead technique. Root runs were produced using TIG (Tungsten Inert Gas) (141) process, while filling and face runs were welded manually with coated electrodes (111). The joints made in a conventional manner after welding were subjected to the relief annealing at temperature of 770oC during 3 hours. Welded joints were subjected to non-destructive examination (VT and RT) and the destructive testing (static tensile testing, impact testing, side band testing and hardness measurements). The results of these tests are described in the article . This article presents the results of structural testing using the light microscopy (LM), as well as the scanning (SEM) and transmission (TEM) electron microscopy. The scope of the structural examination included: examining the microstructure of joints in the respect of delta ferrite content and coarse grain structures of heat affected zone (HAZ) and comparing the morphology of those areas as well as determining the types of carbide precipitates in HAZ of the joint produced with and without post-weld heat treatment. On the basis of the conducted testing it is possible to find the following: – the joints in welded joints produced using temper bead technique with coated electrodes Chromet WB2 of Metrode company are characterised by greater content of delta ferrite when compared to joints welded using electrodes Thermanit MTS 5 Co1 by Böhler; – coarse grain structure of HAZ in joints welded using temper bead technique is characterised by the higher density of dislocation and smaller size of subgrains if compared to the same area in joints welded with post-weld heat treatment; – in the coarse grain structures of HAZ in joints welded with and without post-weld heat treatment it is possible to observe carbides of M23C6 type, NbC and carbonitrides V(C,N).
Keywords: conventionally welded steel pipes, temper beads, microstructure of joints
Analysis of a start-up type influence on tension and strain component waveforms for a selected thick-walled element working in power industry
Presented are selected results of a comparison made between two types of a power unit start-up - the “hot” and the “cold” ones. The subject of the analysis was a steam valve and presented are results of a numerical modeling performed for this element. Ascertained is, on the basis of calculations, that the “cold start-up” is more dangerous for thick-walled elements working in thermo-mechanical fatigue conditions because of the possibility of plastic strain occurrence.
Keywords: power unit start-up, hot start-up, cold start-up, numerical modeling, plastic strains, thermo-mechanical fatigue
Stanisław MROZIŃSKI, Grzegorz GOLAŃSKI
Influence of scientific method on fatigue characteristics of cast steel determined at elevated temperature
The paper presents the results of low cycle fatigue tests of martensitic GX12CrMoVNbN9-1 cast steel subject to the loading effect at constant amplitude of strain and the test of gradual growth. The tests at constant amplitude of total strain were performed for five values of strain εac= 0.25; 0.30; 0.35; 0.50; 0.60%. The tests of gradual growth were carried out in the form of repeated blocks of 100 cycles with the load increasing gradually. Fatigue tests were performed at the temperature of 500oC. The conducted research has shown that the material data obtained in the experiment are similar regardless of the method applied to determine the data. It allows applying simplified method (the test of gradual growth) in order to determine the fatigue properties of metallic materials.
Keywords: cast steel, fatigue tests, methods of fatigue characteristics investigation
Jerzy OKRAJNI, Mirosław PIETRZYK, Marek PLAZA, Donat RENOWICZ, Dariusz KOWALA, Bogusław PLAZA
The effect of modification method of suspension of the water separator on the dynamic characterisitics of the system
The study presents a way of solving a limit of amplitude problems of displacement the fastening system of the water separator, in suspensions which found the presence of cracks, caused by fatigue in the working conditions. The results of modal analysis and time-varying characteristics of displacements the selected points of the system, designated by selected extortion based on dynamic analysis were shown. Existing system and new design solution, which ensures reduction of mechanical vibrations amplitude occurring in operating conditions were compared.
Keywords: power boiler separators, fatigue processes, vibrations of pipelines and fixings
Jerzy OKRAJNI, Mariusz TWARDAWA, Kazimierz MUTWIL
Computer model validation of a live steam pipeline wye connection
The main purpose of this work is to determine the behaviour of power plant components operating under mechanical and thermal loading. Computer FEM modelling of temperature fields along with temperature measurements in the industry conditions have been applied as the methods of research. The results of modelling and measurements have been compared and possibility of using the FEM modelling for the proper description of the changeable with time temperature fields has been shown.
Keywords: steam pipelines, tensions resulting from temperature changes, computer models
Grzegorz NOWAK, Andrzej RUSIN
Stress modelling in turbine components by means of artificial neural network
The paper discusses the problem of on-line stress determination within the main turbine components for the needs of monitoring systems. In such a case the stress must be computed in real time on the basis of on-line acquired operational data. One of the possibilities for rapid stress evaluation is the use of Artificial Neural Network. This tool, if properly trained on the basis of former Finite Element simulations, can successfully be used in the stress monitoring systems.
Keywords: steam turbines, tension modeling, neural networks
Eugeniusz RUSIŃSKI, Michał PADUCHOWICZ, Piotr ŚMIETANA, Artur GÓRSKI, Marcin DĄBROWSKI
Life assessment of 215 MW steam turbine components
There is presented the methodology of durability determining for selected steam turbine components such as the external body, quick-closing valves and flow regulating valves. The analysis concerned a height pressure part of the steam turbine with the power equal 215MW. The geometric model of the of the machine was build, and then was digitized using the finite element method. Transient thermo-mechanical analysis was performed in the next step for these elements. The reduced stress and strains, obtained in this way, were used as input data to determine the residual life of the turbine components. It was made using with one of the damage accumulation theory.
Keywords: 215 MW steam turbines, durability of HP part elements, numerical simulations
Tomasz SAMBORSKI, Andrzej ZBROWSKI
Strength tests of power suspension clamps
The article presents the results of strength tests of selected suspension clamps of power cables used in low voltage overhead lines. In their investigations the authors used the Instron 5583 testing machine with the Bluehill 3 Testing Software and the rapid Phantom V310 camera enabling the recording of the phenomenon of brittle fracture of loaded elements. In parallel to laboratory tests numerical simulations of the MES stand, compliant with the manufacturer’s requirements, were carried out. The identification of areas critical in terms of mechanical strength, together with the correctly described properties of the tested structural material enabled the authors to correlate laboratory results with the MES simulation. Knowledge acquired in that way will allow a more efficient design of products with similar functional properties in the future.
Keywords: power cables, cable clamps, clamp strength
Tomasz STECHNIJ, Stanisław ZABORSKI
The influence of temperature gradients during the laser cutting of the photovoltaic silicon plates on the properties of the silicon cells
The article focuses on the process of cutting silicon photovoltaic plates which was shown on the sample measurements of micro-hardness. As a part of the investigation process, measurements of electric properties were performed, though they were not discussed in the article for editing reasons; however, the article presents conclusions drawn from the measurements. The aim of the investigative cycle was to determine certain changes of electric properties of silicon plates under the influence of the thermal gradient during the cut processing.
Keywords: solar cells, photovoltaic silicon, silicon plates cutting
Zdzisław ŚLODERBACH, Mirosław WITOŚ
The methodology for determining the allowable parameters of the rotors one-sidedly hung taking into account applicable standards and the effectiveness of vibration isolation
In the paper a procedure and methodology of acceptable calculations of powers, displacements (of amplitudes) and velocities of pulses according to ISO standards depending on the speeds (frequencies) rotational of rotor during attempts of dynamic breaking down taking into account effectiveness of vibration isolation were described. The proposed method is regarding one-sidedly hung rotors appearing in such appliances e.g. rotors of fans, blowers, pumps. As permissible parameters of pulses values which are given in international standards PN-ISO-10816-1:1998P and PN-ISO-7919-1:2001 were assumed. In the end also closing remarks and conclusions were given.
Keywords: rotating machines, rotor vibrations, vibroisolation
Mariusz TWARDAWA, Wiesław ZABŁOCKI, Olgierd ŻELAZKO, Krzysztof JANECZEK
New 910 MW coal-fired power unit with ultra-supercritical steam parameters in Elektrownia Jaworzno III – boiler design solutions
On 04/17/2014 has been signed Contract between TAURON Wytwarzanie S.A. and the Consortium RAFAKO S.A. (leader) – Mostostal Warszawa S.A. for the construction of full turnkey 910 MW power unit. Construction of a new Power Unit has huge significance for the Polish power sector. The most and the best available technology and the global experience in the construction and equipment of new large Power Unit will be used in the investment. The new Unit will fulfill all requirements under the EU Directive concerning pollutant emissions into the atmosphere. The investment is also very important for the reconstruction of Jaworzno Power Plant energy production capacity and also for the continued development of the region, where it will be located. Fuel for the new unit will come in nearly 80 percent from the mines belonging to the group TAURON. The new unit will produce annually 6,5 TWh of electricity, equivalent to 5 percent of the current domestic consumption of energy. The article presents the main technical solutions to be applied in the field of boiler of new 910 MW Unit.
Keywords: 910 MW coal-fired power unit, steam boiler, projects
Research and development of the metal magnetic memory method
Theoretical background of the metal magnetic memory method has been presented in the paper. Moreover, the scope of research and development, which are conducted in polish scientific centers in order to verify, confirm this non-destructive method and extend its operational abilities on diagnosing of progressive metal degradation, has been also described. Presented topic has been illustrated by means of examples regarding problems of polish power industry.
Keywords: rotating machines, rotor vibrations, vibroisolation
Andrzej WARACHIM, Krzysztof DEKARZ
Modular construction of container power stations for MV networks
Presented is the modular system of PF-P type MV power stations casings in the aspect of functionality and possibility of application of the newest ICT technology. Attention is paid to the security of applied solutions. Described are adaptation possibilities of the system to the needs of an investment realization process optimization.
Keywords: MV networks, MV power stations, modular constructions
Dave HANSON, Kevin LI, Jorge PLASCENCIA, Clair CLAIBORNE, Donald CHERRY, George FRIMPONG
Understanding dissolved gas analysis of ester fluids (thermal decomposition of ester fluids)
Proved is that the chemical composition of electrical insulating fluids has an influence on their chemical reactivity during faults in high-voltage equipment. Differences occurring in structures of natural ester liquids raise a question concerning differences in chemical reactivity. Pointed out are some existing differences and the similarities amongst which reactions of acids as well as carbon and ethylene oxides formation belong to the most significant. Analyses of samples coming from the working equipment, where various thermal faults can take place, prove that results of DGA can be applied in evaluation of diagnostic equipment using ester fluids.
Keywords: electrical insulating ester fluids, pyrolysis of natural and artificial esters, analysis of gases dissolved in electrical insulating oils (DGA)