Ryszard BARTNIK
A search for an optimum investment strategy in power industry. Methodology and results of sample calculations
The carried out calculations show that application of CCS technology for oxy-combustion in coal-fired power plants is economically entirely unjustified. A very high production costs of electricity generated in such plants will not only result in, and that is of crucial importance, possible bringing an end to economic growth in countries where CCS technology would be in use but also in the lack of social approval and civil disturbances caused by substantial increases in electric energy prices. One must here remember that the cost of electricity generated by coal-fired units with the CCS technology is at least twice as big as the same cost for units without this technology. Moreover, it is even significantly higher than the cost of energy produced in nuclear plants though the specific investment expenditure (per one unit of installed capacity) on a nuclear power unit is twice as high.
Keywords: power industry, investment strategies, CCS technology unprofitability
Kazimierz OZIEMBLEWSKI, Ksawery OPALA
Static stability of electric power systems. Power swings
Presented is here the research on changes of a power system working parameters in conditions of the growing power flow. The results of these and similar examinations can lead to broadening of actual ideas concerning network stiffness, its stability and conditions in which the power swing in a system emerges. Power swings become often the beginning of major system breakdowns.
Keywords: electric power systems, power swings, system breakdowns
Filip KLEPACKI
Assessment of a power boiler ability to work with exceeded rated output
Presented is the conduct and results of research and analyses composing the assessment of a power boiler ability to work with exceeded rated output. The results show that rising the calculated pressure in cooling water and live steam circuits by 0,4 MPa is not dangerous for a boiler further operation. The obtained pressure values during trial unit operations with outputs > 675 t/h were less than the „new” calculated pressures so the user has still some level of operational tolerance. Preparation, in the project framework, of the available documentation careful analysis together with technical condition assessment and equipment inventory has helped the user to update and systematize his knowledge concerning the specific appliance.
Keywords: power boiler, assessment of a power boiler ability to work with exceeded rated output
Jarosław ADAMSKI, Andrzej BALCERZYK, Stanisław LALIK
Industrial research of gas-tight tube walls and coils made of the new generation steels
The paper presents the results of macro- and microstructure and hardness measurements submerged arc welded joints of elements gas-tight tube walls and coils made of steels X12CrCoWVNbN12-2-2 (VM12SHC) and TP347HFG and composite tubes made of steels 3R12 (ASME 304L) and 4L7 (grade. ASME SA-210A1). Welded joints were taken from experimental panel wall. It has been shown that the developed technologies of welding of the above tubes meet the requirements of acceptance.
Keywords: industrial research, gas-tight tube walls, coils made of the new generation steels
Janusz BADUR, Sebastian KORNET, Daniel SŁAWIŃSKI, Paweł ZIÓŁKOWSKI, Mariusz BANASZKIEWICZ, Anna REHMUS-FORC
Threats caused with the fissuring of the cover of the thermocouple in the regulatory degree of the steam turbine
In the work one carried out the fracture process analysis of the cover of the thermocouple in the regulatory degree of the steam turbine. One elaborated the model of the turbine to calculations with the method of finite volumes. One designated the fields of the static pressure of the steam for following temporary steps and the fields of the vector of the speed on area passing through the thermocouple cover. Then one designated changes of the difference of the total pressure between the side of the influx, and with the side of the run-off of protruding in the flow channel of the end of the cover. One made calculations of strength and Eigen frequencies depending on the temperature. Eigen frequencies were set against with values of extortions, what enabled the statement that loads caused with the flow of the steam had not been at the bottom of fracture of the covers of the thermocouple of the analysed turbine.
Keywords: analysis of the cover of the thermocouple, steam turbine
Michał BIENIEK, Paweł URBAŃCZYK, Andrzej RUSIN, Adam WOJACZEK
Analysis of possibility of the SPT method usage in material state assessment for power industry
Determining material properties is one of the main problems during technical state assessment of power plant machines and devices. The traditional testing methods such as tensile test or Charpy impact test can be used to do this, but those methods need quite big samples. The other way is using new methods like Small Punch Test (SPT) method which use micro samples. In this article the possibility of SPT method usage in determining yield stress and tensile strength was examined.
Keywords: Small Punch Test (SPT) method, power industry
Janusz DOBRZAŃSKI, Hanna PURZYŃSKA
The life-time fractures rule in the assessment of exhaustion degree
The method for estimating the exhaustion degree using the life-time fractures rule proposed by E. L. Robinson was discussed. The method for determination of exhaustion degree based on the example of creep tests with elongation measurement during testing carried out on X12CrCoWVNb12-2-2 (VM12SHC) steel coils was presented. The tests were performed until destruction at a constant temperature and changed stress level and at a constant stress level and cyclically changed temperature. The assessment of suitability of the life-time fractures method for practical application in calculation of exhaustion degree was made.
Keywords: the life-time fractures rule by E. L. Robinson, assessment of exhaustion degree
Ihor DZIOBA, Andrzej SKRZYPCZYK, Sebastian LIPIEC
The fracture toughness – temperature dependences of laser welded joints from 13CrMo4-5 steel
In the paper are presented the results of the microstructural, tensile and fracture toughness properties researches, of the laser welded joint, which was made from 13CrMo4-5 steel. It was shown that tensile and fracture toughness properties for weld and heat effect zone material has higher values in comparison to ones for base material for all tested temperatures, from -80 to 20oC.
Keywords: the fracture toughness, temperature dependences, laser welded joints from 13CrMo4-5 steel
Grzegorz GOLAŃSKI, Anna ZIELIŃSKA-LIPIEC, Adam ZIELIŃSKI, Paweł URBAŃCZYK
Microstructre of T91 steel after long term service
The paper presents the results of research on the microstructure of X10CrMoVNb9-1 (T91) steel after around 105 000 hours of service at the temperature of 540oC. The test sample for research were taken from a coil of a boiler superheater. After service, the examined steel was characterized by a retained lath microstructure of tempered martensite with quite large density of dislocations and numerous precipitations: M23C6 and MX precipitates. The service has mostly contributed to the precipitation of the Laves phase and the Z phase precipitations. Moreover, the processes of recovery and polygonization of the matrix, as well as coagulation and spheroidization of M23C6 carbides and Laves phase were observed.
Keywords: microstructre after long term service, T91 steel
Adam HERNAS, Robert WERSTA, Tomasz LUCZYS
Characteristic of dissimilar welded joint made of P91 steel with 13CrMo4-5 steel after 240 000 hrs of service
The paper presents some results of microstructure and hardness analysis of dissimilar welded joint made of P91 steel in initial state with 13CrMo4-5 steel after 240 000 hrs of service. Technological conditions, welding and thermal treatment parameters of welded joint pipes with diameter φ 323.9 mm and thickness 33.3 mm are presented. As a additional welding material used to wire WMoVSi / EMoVB42H5 usually designated to welding of 14MoV6-3 steel. The proper macro and microstructure with the use of the light and scanning microscopy as well as hardness distribution was found. The quality of welded joint complying with requirements of Polish technical supervision (UDT).
Keywords: dissimilar welded joint made of P91 steel with 13CrMo4-5 steel
Katarzyna MAKOWSKA, Zbigniew L. KOWALEWSKI
Possibilities of Barkhausen noise application for microstructure and mechanical properties evaluation
This work is an attempt for estimation of mechanical properties variations by means of the selected parameter characterising Barkhausen noise. An influence of material microstructure on the Barkhausen noise level was presented. The specimens of power plant steel were subjected alternatively to prior deformation due to accelerated creep or plastic flow. Each of these processes was interrupted for a range of the selected time periods in order to achieve specimens with increasing level of prestrain. The specimens after prior deformation were tested using magnetic method, and subsequently, they were subjected to static tensile tests. In the final step of work some relationships between the conventional yield point and selected parameter characterising Barkhausen noise were analysed.
Keywords: microstructure and mechanical properties evaluation, Barkhausen noise
Stanisław MROZIŃSKI, Grzegorz GOLAŃSKI, Jacek SŁANIA
Fatigue properties of L21HMF cast steel after heat treatment
The paper presents chosen results of comparable studies of L21HMF cast steel after service and after regenerative heat treatment. The cast steel was subject to tests in the conditions of static and changeable loads. The tests were carried out at room temperature. The obtained results were used for performing a comparative analysis of the basic parameters of hysteresis loops received in the same load conditions.
Keywords: regenerative heat treatment, L21HMF cast steel
Grzegorz NOWAK, Adam ZALEWSKI
The influence of thermal expansion coefficient on the stress state during start-up of supercritical steam turbine
The rise of steam parameters of power units beyond the critical point leads to a significant increase of thermo-mechanical loading of turbine components. The high intensity of heat transfer between the working medium and the solid material during unsteady operation (start-ups) results in dangerous stresses developed in a massive inner casing. In this paper the influence of the thermal expansion coefficient of shrink rings connecting the casing parts on stress within the casing is investigated. It can be seen that rough estimation of material parameters may lead to underestimation of modeled stress.
Keywords: the influence of thermal expansion coefficient on the stress state, supercritical steam turbine
Eugeniusz RUSIŃSKI, Michał PADUCHOWICZ, Piotr ŚMIETANA, Artur GÓRSKI, Jerzy CZMOCHOWSKI, Marcin DĄBROWSKI
Methodology of remaining lifetime assessment of the working in a cogeneration cycle 105 MW steam turbine selected elements
Presented is the methodology of remaining lifetime assessment of selected steam turbine components such as quick-closing valves, control valves and loop pipes. The analysis concerned a high pressure part of the steam turbine with output power of 105 MW. The geometric model of the appliance was built and then digitized with the use of finite element method. As the next step a transient thermo-mechanical analysis was performed for these elements. Obtained in this way values of reduced stress and strains served then as input data to determine residual life of the turbine components by using Palmgren-Miner linear damage accumulation theory.
Keywords: remaining lifetime assessment of a steam turbine elements, 105 MW steam turbine
Zdzisław ŚLODERBACH
Geometrical and deformation effect resulting from the EU-directive concerning bending pipes for great deformations
In paper the relations to calculate the maximum value of relative strains, which occur in a process of bending of tubes on benders, in stretched layers of tubes, are presented in this work on the basis of EU-directive concerning production of pressure equipment. It has been shown that for large deformations that occur during bending of the pipes on knees, logarithmic strain measures (real) and relative strain measures give different values of strain but equal wall thicknesses in the bending zone. Logarithmic measures are frequently used in engineering practice and are valid for large and small deformations. Reverse expressions were also derived to calculate the required initial wall thickness of the tube to be bent, in order to obtain the desired wall thickness of knee after bending.
Keywords: the EU-directive concerning bending pipes for great deformations