Ryszard BARTNIK, Zbigniew BURYN, Anna DUCZKOWSKA-KĄDZIEL
To modernize the existing coal-fired power plants whether to construct new ones?
A technologically and technically rational opportunity for the modernization of existing coal-fired power plants, thus offering their modernization is associated with a conversion into dual-fuel gas-steam systems. The dual-fuel technology offers an additional benefits of modernizing the power engineering sector with the lowest possible expenditure. Such adaptation is 4 times less expensive per specific unit of the electrical capacity (it is estimated at 1.6 million PLN/MW) in comparison to the construction of a power unit for supercritical parameters (the investment is estimated at 6.5 million PLN/MW). In comparison, nuclear power engineering is 12 times more expensive in investment, which is estimated at 18 million PLN/MW. In the consideration of the above, it is necessary to find an answer to the following. Is it economically justified to modernize the existing coal-fired power units to dual-fuel gas-steam systems, which; however, burn expensive natural gas? Is it more justified to undertake the construction of new expensive power units for supercritical parameters which are fired by the relatively cheap coal? What are the justified relations between fuel prices and what ranges should they take in order to guarantee high economic efficiency of the examined technologies?
Keywords: modernization of coal-fired power plants, gas-steam systems, comparisons with ultra supercritical power units
Janusz ĆWIEK, Jerzy ŁABANOWSKI, Maria SOZAŃSKA
Assessment of predicted life of waterwall tubes with protective coatings
Diagnostic tests of protective coatings – the thermal sprayed Al2O3/Ni-30Cr and the hybrid one laid with the use of painting technology – working on waterwall tubes in low-emission pulverised fuel boilers prove, among the others, that protective coatings do not secure the heating surface of waterwall tubes from flame corrosion. The additional cause of the short life of coatings is a high sulphur and chlorine content in coal as well as co-combustion of biomass.
Keywords: low-emission power boilers, waterwall tubes, protective coatings
Leszek Adam DOBRZAŃSKI, Małgorzata MUSZTYFAGA
Laser sintering of the front electrodes in silicon solar cellsh
Investigations included in this study represent a response to the growing energy demand for new high-performance solutions, renewable energy. The use of modern laser techniques enable to automate and intensive development of the various stages of manufacture of solar cells. The paper presents the application of laser techniques for designing material’s properties and its structure, among other things, the selective laser sintering of front electrodes on silicon surface, which guarantee the improvement of electrical properties of solar cell.
Keywords: photovoltaics, solar cells, laser sintering of electrodes
Ihor DZIOBA, Robert PAŁA
Influence of a sample thickness on its crack resistance
Analysed is the influence of a sample thickness, B, on the crack resistance critical value, KJC. There is proved that KJC values are not constant even for the range of thicknesses which meet standard requirements. Ascertained is that KJC value depends on the level of TZ and Q values which characterize stress condition in the sample.
Keywords: sample thickness influence on crack resistance, stress condition
Mirosław GAJEWSKI, Leopold BARWICKI
Experience from welding thick steel piping P92
This paper presents the characteristics of P92 steel. Demonstrated the dependence of hardness and toughness of the steel tempering temperature of X20CrMoV 12-1 and P92. Butt joints of pipes with a diameter of 508 x 34 mm of steel P92 were studied. The paper presents the reasons for obtaining low toughness welds. Morphology of non-metallic inclusions in joints and their influence on the process of cracking were specified.
Keywords: P92 steel characteristics
Grzegorz GOLAŃSKI, Cezary KOLAN, Joanna KĘPA, Jerzy KUPCZYK, Stanisław MROZIŃSKI
Changes in the cast steel GX12CrMoVNbN9-1 microstructure after being subjected to the low-cycle fatigue
The paper presents the results of an independent research on the influence of low-cycle fatigue at room temperature and 600°C on the microstructure of high-temperature creep resisting high-chromium GX12CrMoVNbN9 – 1 (GP91), cast steel. The characteristics of the microstructure of the examined cast steel after low-cycle fatigue was made by means of transmission electron microscopy and included an analysis of the dislocation microstructure and morphology of carbides. It has been shown that the low-cycle fatigue of GP91 cast steel leads to the processes of recovery and polygonization of the matrix, as a result of a decrease in the dislocation density and growth of subgrain width. Additionally, at an elevated temperature (600°C), it results in the process of coagulation of M23C6 carbides. Intensity of the above-mentioned processes depends not only on the temperature of testing, but also on the level of total strain amplitude εac. This proves the advantage of softening processes in the GP91 cast steel microstructure, due to low-cycle fatigue, over the strengthening processes, which has an influence on the cyclic properties of the investigated cast steel.
Keywords: high-chromium cast steel, dislocation microstructure
Stanisław GUMUŁA, Małgorzata PIASKOWSKA-SILARSKA
Counter-arguments to the thesis of high harmfulness of carbon dioxide emission to the atmosphere
This paper presents positive and negative arguments related to CO2 emission to the atmosphere. There are considered aspects like absorption of radiation in the atmosphere in correlation to concentration and temperature of CO2, changes in concentration of CO2 in longer or shorter time periods, vacillation of ocean surface level, relation between temperature changes from its the average and the sun activity.
Keywords: energy crisis, virtual influence of CO2 emission, greenhouse effect
Stanisław GUMUŁA, Katarzyna STANISZ
Autonomic electroenergetic systems using renewable sources and energy accumulation
The paper presents two variants of autonomic electroenergetic systems for detached houses based on the use of renewable energy sources. The first system is based on the photoelectrical conversion of solar radiation energy into electrical energy, however the other system on the conversion of wind kinetic energy into electrical energy. The paper presents relationship power and area of photovoltaics and the approximate power of the wind turbine at a given wind speed, the daily demand for electricity, and relationship capacity of electrical energy accumulators for the collection of produced energy by photovoltaic system or wind turbine.
Keywords: detached houses, renewable energy sources, electric energy supply to buildings
Stanisław GUMUŁA, Agnieszka WOŹNIAK
Selected technologies of electricity production from distributed renewable sources of energy
The easiest way to reduce carbon dioxide emissions while increasing amounts of generated electricity seems to be the dissemination of technologies based on renewable energy sources or a combination of renewable energy sources with conventional technologies. In this study, given a brief description of energy technologies based on the use of solar energy, kinetic energy of the wind, a decrease in surface water, groundwater heat, municipal waste, biomass (biogas, ethanol, diesel) and considered to be the most promising, based on the use of hydrogen (fuel cells, Rhodes Brown’s gas).
Keywords: CO2 emission reduction, renewable energy source, hydrogen power engineering
Adam HERNAS, Przemysław JAMROZIK, Jerzy PASTERNAK, Stanisław FUDALI
Characteristics of structure alloy welds HR6W
Alloy HR6W is preferred for boiler components operating parameters of supersupercritical. The study materials were uniformly welded joints manually and automatically alloy 23Cr – 45Ni – 7W. Pioneering research is conducted across the country and enable you to get experience and your own „know – how” in the field of welding and tube bending. Non-destructive tests were performed and the basic structure of the mechanical properties. Qualification achieved tube bending technology carried out in accordance with PN EN – 12952 and welding carried out in accordance with PN – EN 15614.
Keywords: power boilers, boiler constructions, light-wall tubes
Robert JACHYM, Krzysztof KWIECIŃSKI, Mirosław ŁOMOZIK, Michał URZYNICOK, Paola MARIANI, Yusuke MINAMI
Properties of thick welded similar and dissimilar joints made of TEMPALOY A-3 steel assigned for power industry
This article presents experience gained while welding similar joints of steel TEMPALOY A-3 and dissimilar joints of steels TEMPALOY A-3 and T91, with the use of EPRI87. The destructive and non-destructive tests were carried out according to the PN-EN ISO 15614-1/A1:2010 standard. All joints are characterised by high quality, which is confirmed by the results of destructive and non-destructive tests. The tests involving the said steel grades belong to the very few carried out in the world.
Keywords: boiler steels, supercritical parameters boilers, boiler steels welding
Krzysztof J. JESIONEK
Damage of the BABCOCK boiler tube insert
Presented is an example of a non-standard accident during which the exhaust heat boiler tube insert lost its leak tightness after only a short operating time.
Keywords: power boilers, damage of a boiler tube insert
Zbigniew L. KOWALEWSKI, Lech DIETRICH, Dominik KUKLA, Paweł GRZYWNA, Tadeusz SZYMCZAK
Damage parameters under fatigue and their measures
Selected damage measures applied for degradation description of engineering materials subjected to fatigue loading conditions are presented. In addition to well-known measures the new concepts of fatigue damage development are discussed using known mechanisms of cyclic plasticity and ratcheting.
Keywords: engineering materials fatigue, damages
Adam KRUK, Grzegorz MICHTA, Artur BLUM
Metallographic and acoustic emission analysis of structural steel with nonmetallic inclusions
The aim of this study was to analyze the development of cracks formed on the nonmetallic inclusions and their propagation during increasing static load applied to the sample. For this purpose, non-destructive test method which is the acoustic emission (AE) was applied. The study was performed on parts metal cut from the lower part of the belt (tension) a long-time operated the bridge box girder crane made in the 60s the last century, containing a large amount of large non-metallic inclusions.
Keywords: structural steel, metallographic analysis, girder crane damages
Andrzej KUREK, Adam NIESŁONY
Fatigue strength of titanium SB 265 G1 used in production of explosively welded materials for energy industry
The paper presents fatigue tests results of bimetal steel-clad titanium explosively welded. The study involved specimens made of bimetal which is a combination of steel S355J2 with titanium SB 265 G1, which was imposed in the process of material cladding and both basic materials.
Keywords: fatigue tests, titanium, steel-titanium bimetal
Marta KUREK, Tadeusz ŁAGODA, Franck MOREL
Fatigue life estimation alloy steel 35NCD16 under random loading
The paper concerns predicting the fatigue life of the material 35NCD16 (36NiCrMo16) under random loading. High alloy steel 35NCD16 characterized by a lack of mutual parallelism of fatigue characteristics for bending and torsion. For such materials the fatigue life estimation, standard models shoudn’t be used, because they do not take into account the variability relative to the tangential and normal stress. The aim of the work is to compare the experimental results of the calculation using the proposed model obtaining satisfactory results.
Keywords: alloy steel 35NCD16, fatigue life, random loading
Fatigue life of welded joints including structural geometrical notches
The paper presents typical approaches to fatigue life determination for welded joints. Special attention has been paid to the nominal approach. It gives the worst results but it is the simplest and reliable method. It has been shown that this method does not include a kind of steel, and it seems not to be a correct solution because highstrength steels introduce an important structural notch (i.e. change of the structure) and internal stresses after welding. Finally, in the paper a method of including both geometrical and structural notches was proposed for fatigue life determination for steel welded joints.
Keywords: fatigue life, welded joints
Mirosław ŁOMOZIK, Krzysztof KWIECIŃSKI, Robert JACHYM, Michał URZYNICOK, Paola MARIANI
Mechanical properties of butt welds in PB2 steel pipes welded using conventional and temper bead technique
The article presents various variants of circumferential butt welding of thick-walled pipes of X13CrMoCoVNbNB-9-2-1 (PB2) steel using filler materials supplied by two different producers. The welds were produced in two ways: with postweld heat treatment and without it but using temper bead technique. The results of welded joints mechanical properties investigation such as: tensile test, impact test, side bend test and hardness measurement are presented and compared. It has been found that welded joints produced using temper bead technique without postweld heat treatment are characterised in general by low values of absorbed energy by a material in the weld area. The presence of delta ferrite in the microstructure of welds and high hardness of martensite are the reason for low ductility of the material.
Keywords: butt joints of PB2 steel pipes, mechanical properties
Michał PADUCHOWICZ, Artur GÓRSKI, Artur ILUK, Jerzy CZMOCHOWSKI
Selected problems of displacements and stress analysis of ROFA INSTALLATION air channels
The paper presents the issues related to the assessment of the effort state of designed installation for minimizing the emission of nitrogen oxides in the form of hot air ducts. One of the aims is to present the results of simulation tests, which resulted in the optimal dimensioning of geometric form of the supporting structure of air channels and how to suspend, support and integrate the channels by special compensation elements. During the work the FEM numerical models were built of the following parts of air ducts. The use of shell elements allowed for a thorough analysis of effort of the entire facility for selected load conditions in cold and hot state. The influence of the way of support, suspension and connection of different sections of channels by the specific compensation elements.
Keywords: flue gas denitrification system, air ducts, construction of suction and pumping air ducts
Marek PLAZA, Jerzy OKRAJNI, Mirosław PIETRZYK
Dynamic model and modal analysis on the example of a selected power boiler tube circuit
Presented is the analysis of behaviour of a power unit water separator with its suspension system. Cracks in the suspension tension members occurred as a result of vibrations caused by the boiler water-steam mixture turbulent flow. Modal analysis and numerical simulation of the circuit model vibrations enabled elaboration of an additional vibration damping system protecting the water separator suspension elements against fatigue cracking.
Keywords: power unit, tube circuit, power unit water separator
Andrzej RUSIN, Adam WOJACZEK, Michał BIENIEK
Selected aspects of the assessment of life and of supporting decisions concerning overhaul of power unit components with a long operating life
The paper discusses selected aspects of assessment of the technical condition of power engineering devices and machines as well as those related to the planning of overhauls of such machines and devices. Various factors were considered influencing the quality of theoretical assessment of the degree of components life consumption caused by creep and fatigue, as well as crack propagation. Probabilistic methods are recommended in such analyses. As far as actions supporting diagnostics and overhaul management are concerned, the possibility was pointed out of using risk analysis and diagnostic tests in the planning of reasonable overhaul intervals.
Keywords: power units, long operating life, power units overhaul
Tomasz SAMBORSKI, Andrzej ZBROWSKI, Michał ROKOSZ
Numerical simulation of the thermal state of the chamber for thermal tests of servomotors
At the Institute for Sustainable Technologies – National Research Institute, Radom, Poland a system for electromechanical drive tests was developed. Electromechanical drives are, inter alia, used in fire protection systems and process engineering that require the flow of the medium to be controlled by means of actuator-driven valves. A climatic chamber is a crucial element of the test system as it allows for the determination of the influence of alternating thermal conditions on work parameters of electric servomotors. In order to verify the design assumptions, a numerical simulation of the thermal state in the chamber was conducted in the temperature range of – 35 to + 120°C.
Keywords: electromechanical drives, drive testing systems, climatic chamber
Tomasz STECHNIJ, Stanisław ZABORSKI, Dariusz POROŚ
The methods of the rating in silicon plates of photovoltaic cells
Publication contains chosen examples of applied processings, diagnosed by electric parameters. Describes the conditions of the edge of photovoltaic silicon after the cut process. The sequence of the tests of the conventional cutting in the silicon cell carried out by disc cutting. Then analyses of surfaces were executed, being derivative of the applied parameters in the methods of the cut of silicon wafers. Conclusions guide to drawing significant relationships between the condition of the surface after executed cuts of silicon and the usable parameters of solar cells. PV systems will be happened the cheap and popular figure of the energy conversion. Refining the solutions in the range of the productive process of typical silicon cells is the necessity, especially through the more effective technics of the separation material and by the building the criteria of the rating of the condition their surface after cutting.
Keywords: photovoltaics, silicon plates in photovoltaic cells, plate machining
Closed system of thermo-elastic-plastic couplings. Part I. Closed system of thermostatic equations and couplings effects diagram
In this first part of paper the field equations of the generalized coupled thermoplasticity theory are derived using the postulates of classical thermodynamics of irreversible processes. Using the Legendre transformations a two new thermodynamics potentials P and S depending upon internal thermodynamic forces Π are introduced. The most general form for the all thermodynamics potentials are assumed instead of the usually used additive form. Due to this assumption, it is possible to describe all the effects of thermomechanical couples and also the elastic-plastic coupling effects observed in such materials as rocks, soils, concretes and in some metallic materials.
Keywords: thermoplasticity, thermodynamics of irreversible processes
Closed system of thermo-elastic-plastic couplings. Part II. Constitutive and rate equations
In this second part of paper not only the usually postulate of existence of a dissipation potential (the Gyarmati postulate) but also general method are used to derive the velocity equation. The plastic flow constitutive equations have the the character of non-associated flow laws even the gyarmati postulate is assumed. In general formulation the plastic strain rate tensor is normal to the surface of generalized function of plastic flow defined in the the space of internal thermodynamic forces Π but is not normal to the yield surface. However in general formulation and after use the gyarmati postulate, the direction of the sum of the plastic strain rate tensor and the coupled elastic strain rate tensor is normal to the yield surface.
Keywords: plastic flow velocity equations, plastic and elastic strain rate tensor