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1
Content available Thermodynamic Analysis of Precipitation Process of Complex Carbonitride TixV1-xCyN1-y in HSLA-Type Steel
Wojtacha Anna, Opiela Marek
Advances in Science and Technology. Research Journal
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2022
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Vol. 16, no 4
64--73
EN
The paper presents a detailed analysis of the MX-type interstitial phase precipitation process and a thermodynamic analysis of the TixV1-xCyN1-y carbonitride precipitation in austenite. The subject of research analysis was the newly developed HSLA-type steel containing 0.175% C, 1.02% Si, 1.87% Mn, 0.0064% N, 0.22% Mo, and microadditions 0.022% V and 0.031% Ti. Analysis of the process of precipitation of MX interstitial phases under thermodynamic equilibrium conditions proved that the first phase that precipitates in the austenite of the tested steel is TiN-type nitride. The onset temperature of this phase was 1450°C. Subsequently, carbides of the TiC-type, VN-type nitrides and VC-type carbides, for which the precipitation onset temperatures were 1180°C, 870°C and 775°C will be released, respectively. The analysis of the precipitation process of the complex carbonitride in austenite under thermodynamic equilibrium conditions was based on the Hillert and Staffansson model, developed by Adrian, with the use of the CarbNit computer program. The beginning of carbonitride precipitation with the stoichiometric composition Ti0.985V0.015C0.073N0.927 occurred at the temperature of 1394°C. At 850°C practically all of the Ti is bound in the carbonitride of the stoichiometric composition Ti0.883V0.117C0.378N0.622. At the same temperature, a significant part of microaddition V will be dissolved in austenite, which means that vanadium will have a lesser effect on the formation of a fine-grained austenite structure, but more strongly on the precipitation hardening of steel by the dispersion VN and V particles (C,N) released during the cooling of the products.
2
Content available remote Models using in metallurgical process management
Pustĕjovska Pavlina, Kardas Edyta, Toman Radek, Bařina Dominik, Jursova Simona
Zarządzanie Przedsiębiorstwem
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2020
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Vol. 23, nr 3
16--19
EN
The paper presents the possibilities of the application of different models for blast furnace operation management: thermodynamic and kinetic models and also coke degradation model. Thermodynamic and kinetic approaches in modelling metallurgical processes form are necessary basis for continuous analysis of the conditions under which the evaluated iron technology can actually work while achieving the highest productivity. They can be also useful for estimating of maximal rate of auxiliary fuels in specific conditions of the blast furnace iron making, what can help to optimize the cost of fuels. The aim of the article is to present the possibility of reducing the costs of pig iron production using models, especially the coke degradation model, which was used for Czech conditions. The model was developed in two options: a regressive non-linear statistical model, and a selflearning neuron network. Subsequently, both predictive model variants are compared.
3
Termodynamiczny model elektrociepłowni gazowo-parowej
Lichota J., Kołodziejak P.
Rynek Energii
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2018
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Nr 5
20--29
PL
Artykuł opisuje dwa modele termodynamiczne elektrociepłowni EC-2 w Siedlcach wykorzystujący przemiany izentropowe i politropowe oraz model spalania gazu. Pokazano szczegółowy algorytm obliczeń prowadzonych w modelach. Porównano wyniki uzyskane z modeli z wynikami pomiarów uzyskując dobrą zgodność. Modele można wykorzystać do optymalizacji pracy elektrociepłowni gazowo–parowej pracującej na rynku energii.
EN
This article describes two thermodynamic models of plant EC-2 located in Siedlce. First model uses isentropic expansion, second- polytropic. The paper shows detailed calculation algorithm in models. Results obtained within models were compared with measurements. There were certain differences because of different places of calculations and available measurements. Relations between values were valid e.g. flue gas flow in combustion chamber computed by isentropic model was 81.5 kg/s, measured flue gas flow behind gas turbine was 88-94 kg/s (including additional cooling air flow, which was at second stage of turbine and was not included in calculations), assumed oxygen concentration 9% (=21%-12%) being involved in oxidation reaction in the combustion chamber is smaller than the measured concentration of 15%>12% in flue gases behind gas turbine. Results from models approximately show measurements. It seems that real transformation of CCGT thermodynamic system is between isentropic and polytropic process, because measurements are between results from models. It was shown that relatively simple models can be applied to modelling of gas-vapour cycle. Generated electrical power in both cycles agrees with measurements, computed gas flow in combustion chamber agrees too. It allows for applying that model in economic calculations answering e.g. questions about economic profitability of CHP.
4
Content available Wpływ objętości próbki chemoutwardzalnej żywicy poliestrowej na przebieg jej utwardzania
Kozioł M., Mocek P., Jankowski P.
Polimery
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2016
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T. 61, nr 2
133--141
PL
Zbadano wpływ objętości próbki żywicy poliestrowej na przebieg zmian temperatury oraz na czas utwardzania. Stwierdzono, że wraz ze zwiększającą się objętością próbki żywicy (do 120 cm3) skraca się czas sieciowania i rośnie temperatura maksymalna (szczytu egzotermicznego). Sztywność żywicy utwardzanej za pomocą aktywniejszego inicjatora maleje ze wzrostem objętości próbki, natomiast w przypadku zastosowania mniej aktywnego inicjatora — się zwiększa. Przeprowadzono modelowanie matematyczne termodynamicznego procesu utwardzania żywicy za pomocą modelu układu o parametrach rozłożonych, opisującego sieciowanie determinowane chemicznie z dyfuzją ciepła. Stwierdzono duży wpływ chłodzenia konwekcyjnego na przebieg procesu.
EN
The paper presents an experimental evaluation of the influence of polyester resin specimen volume on the time and temperature of curing process. It was found that the maximum peak temperature increased with an increase of the resin volume up to 120 cm³ (Figs. 4—6) while the curing time was decreased. The stiffness of the resin cured with the use of a more active initiator decreased with an increase in the resin volume and increased when a less active initiator was employed (Figs. 9 and 10). The mathematical modelling of the thermodynamics of curing process was performed using a model of distributed parameters system, describing the chemically determined curing process with heat diffusion. A strong influence of convective cooling on the course of the process was found.
5
Content available A comparative study of thermodynamic electrolyte models applied to the Solvay soda system
Jaworski Z., Czernuszewicz M., Gralla Ł.
Chemical and Process Engineering
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2011
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Vol. 32, nr 2
135-154
EN
Fast development of computation techniques for electrolyte activities contributed recently to introduction of a few substantial programmes for thermodynamic computing of multiphase systems. The presented study comprises useful information for practical computing using selected thermodynamic models of aqueous electrolyte solutions. Those models enable quantitative description of both phase and ionic equilibria and provide values of activity coefficients. The carried out analysis of individual models involved a comparison of their practical effectiveness features along with problems encountered in evaluation of the coefficients. The authors conclude that for the Solvay soda system the exUNIQUAC model for an in-house code or the MSE model for a commercial one can be used.
6
Content available remote A comparative study of two thermodynamic models applied to solutions of the NH3-H3PO4-H2O and NH3-CO2-NaCl-H2O systems
Jaworski Z., Czernuszewicz M., Gralla Ł.
Chemical and Process Engineering
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2010
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Vol. 31, z. 4
789-811
EN
The required number of parameters and their temperature dependences for two models for the thermodynamic description of electrolyte solutions were analyzed. The Pitzer model and the extended UNIQUAC model were applied to systems used in the fertilizer industry, NH3-H3PO4-H2O, and in the Solvay soda technology, NH3-CO2-NaCl-H2O. Feasibility of the derivation of the activity coefficients was also carried out for those systems. The number of required model equations to be applied along with temperature dependences of the model parameters were presented to explain and compare the complexity of the two models. Experimental data correlations for the model parameters available in the literature were presented and the computing results for the two analysed systems were described. It was also concluded that at the present state of knowledge the activity coefficients can be computed for the solution components of the two systems by the extended UNIQUAC method and for the Pitzer model several simplifications have to be applied.
PL
Zanalizowano liczbę niezbędnych parametrów oraz ich zależności od temperatury dla dwóch modeli do termodynamicznego opisu roztworów elektrolitów. Zastosowano model Pitzera i rozszerzony model UNIQUAC do układów zawierających związki stosowane w przemyśle nawozowym, NH3-H3PO4-H2O, oraz sodowym NH3-CO2-NaCl-H2O. Przeprowadzono ocenę możliwości wyznaczenia współczynników aktywności dla tych układów oraz poziomu złożoności każdego z wymienionych modeli pod względem liczby równań i zależności parametrów modelu od temperatury. Zebrano również dostępne w literaturze wartości parametrów obu modeli i opisano wyniki obliczeń z zastosowaniem tych danych do analizowanych układów. Stwierdzono, że aktualny stan wiedzy umożliwia wyznaczenie współczynników aktywności indywiduów chemicznych wchodzących w skład obu układów rozszerzoną metodą UNIQUAC, a w przypadku modelu Pitzera należy zastosować szereg uproszczeń.
7
Content available remote Modele lepkości dla ciekłych żużli
Kalicka Z., Kawecka-Cebula E.
Prace Instytutu Metalurgii Żelaza
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2006
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T. 58, nr 4
42-43
PL
Przedstawiono krótki przegląd metod modelowania lepkości żużli. Omówiono półempiryczne modele Urbain, Iida, Mills i Reddy, oparte na różnych wyrażeniach matematycznych, oraz model termodynamiczny. Zwrócono również uwagę na wpływ stałej fazy zdyspergowanej w ciekłym żużlu na lepkość takiego układu.
EN
A brief overview of modeling of slag viscosity is presented. Semi-empirical methods by Urbain, Iida, Mills and Reddy, based on different mathematical expressions, and thermodynamic model are described. Ań effect of solid phase dispersed in liquid slag on the viscosity is also taken up.
8
Content available remote Nonlinearity and memory effects in low temperature heat propagation
Saxton K., Saxton R.
Archives of Mechanics
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2000
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Vol. 52, nr 1
127-142
EN
In order to account for low temperature heat propagation phenomena in crystals of sodium fluoride and bismuth, we employ a thermodynamic model for rigid materials involving a vector-field internal state variable. The model is either wavelike or diffusive, depending on the temperature regime considered.
9
Thermodynamic analysis of the kinetics of carbonitride precipitation in HSLA steels.
Adrian H.
Inżynieria Materiałowa
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1998
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R. XIX, nr 3
171-178
EN
Precipitation of carbonitride in HSLA steel containing up to three microalloying elements was analysed, using classical theory of diffusion controlled nucleation. For this purpose the driving force for carbonitride nucleation is calculated using a thermodynamic model. The results of calculation show, that the critical nucleus formed at high temperature is richer in N and element having the highest chemical affinity for N compare to the bulk precipitate at equilibrium. On the basis of analysis a kinetic model was developed for predicting start times, for precipitation of carbonitride in austenite.
10
The effect of dissolved vanadium content on the hardenability of HSLA steels.
Adrian H., Adrian A.
Inżynieria Materiałowa
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1998
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R. XIX, nr 3
295-298
EN
The effect of calculated dissolved vanadium content, (V), on the hardenability of medium carbon-manganese HSLA steels containing the complex addition of V, Ti, Nb, Zr and Al was investigated. Calculation of dissolved vanadium content was carried out using the thermodynamic model. The optimum conditions for maximising the vanadium hardenability effect were established.
11
Analysis of the properties of carbonitrides in HSLA steels.
Osuch W., Adrian H.
Inżynieria Materiałowa
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1998
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R. XIX, nr 3
303-306
EN
The results of complex analysis of the size of (Ti, Nb, V) (C, N) carbonitride particles are presented. The morphology of particles, their size distributions and chemical composition were investigated. The results of investigations were compared with calculated data obtained using the thermodynamic model for carbonitrides precipitation in HSLA steels.
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