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    Wyświetlanie 1-9 z 9
    Tytuł:
    Experimental study and mathematical modeling of the residence time distribution in magnetic mixer
    Autorzy:
    Rakoczy, R.
    Kordas, M.
    Grądzik, P.
    Konopacki, M.
    Story, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/778204.pdf
    Data publikacji:
    2013
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    mixing model
    residence time distribution
    modelling
    magnetic field
    Opis:
    This study reports on research results in the field of a mixing process under the action of a transverse rotating magnetic field (TRMF). The main objective of this paper is to present the effect of this type of a magnetic field on residence time distribution (RTD) measurements. This paper evaluates the performance of a magnetic mixer by comparing the results of an experimental investigations in a pilot set-up and theoretical values obtained from mathematical model. This model consisting of the set of ideal continuous stirred tank reactors (CSTR) fitted well the experimental data.
    Źródło:
    Polish Journal of Chemical Technology; 2013, 15, 2; 53-60
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Radiotracer investigations of municipal sewage treatment stations
    Autorzy:
    Farooq, M.
    Khan, I.
    Ghiyas-ud-Din, Ghiyas-ud-Din
    Gul, S.
    Palige, J.
    Dobrowolski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/971492.pdf
    Data publikacji:
    2003
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    wastewater treatment
    residence time distribution
    activated sludge
    radiotracer
    Opis:
    Tracer techniques, which are well-established methods in process dynamics studies in industry, were applied to investigate the dynamics of sewage treatment process. The concept of residence time distribution (RTD) was used to investigate the efficiency of the primary clarifier, aeration tank and secondary clarifier of a sewage treatment plant. Preliminary treatment and modeling of the tracer data was performed using the software DTS Pro Ver. 4.20. A big short - circuiting (by-passing) with a large volume of stagnant zones were found in the primary and secondary clarifiers, while no stagnant zone was detected in the aeration tank.
    Źródło:
    Nukleonika; 2003, 48, 1; 57-61
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modeling and simulation of vertical roller mill using population balance model
    Autorzy:
    Fatahi, Rasoul
    Barani, Kianoush
    Powiązania:
    https://bibliotekanauki.pl/articles/1449686.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    vertical roller mill
    modeling
    simulation
    cement grinding
    residence time distribution
    Opis:
    There are few studies concerning the process simulation of vertical roller mills (VRMs). In this research work, the application of population balance model for simulation of a VRM in a cement clinker grinding circuit was investigated. The residence time distribution (RTD) was measured, and the tank-in-series and Weller models were employed to describe the residence time distribution. Two sampling surveys were carried out on the VRM circuit. The data from the first survey were used for model calibration, and the specific breakage rates were back-calculated. The model parameters obtained were used for simulation of the second survey, and validation of the model. The results showed that the clinker particle spent a short time inside the VRM and the mean residence time is about 67s. The tanks-in series model compares to Weller model was more proper to describe the residence time distributions in the VRM. The simulation results showed that the specific breakage rates increased with increasing particle size. However, the particles larger than 25.4 mm particles sizes are too large to be properly nipped by master rollers. Finally, it can be concluded that the grinding process of the VRM is very well-predictable with the population balance model.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2020, 56, 1; 24-33
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of Twin Screw Extrusion for Continuous Processing of Energetic Materials
    Autorzy:
    Dombe, G.
    Mehilal, D.
    Bhongale, C.
    Singh, P. P.
    Bhattacharya, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/358044.pdf
    Data publikacji:
    2015
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    twin screw extruder
    energetic materials
    rheology
    safety
    residence time distribution
    Opis:
    Continuous processing of energetic materials using a twin screw extruder is gaining importance as it is a safe and cost-effective alternative to conventional batch processing. The continuous process based on a twin screw extruder combines the capabilities of intensive mixing and high pressure extrusion. It is used for processing a variety of energetic materials, such as gun and rocket propellants, plastic bonded explosives, pyrotechnics, thermo-baric explosives, etc. The twin screw extruder process demands various safety features for the processing of energetic materials. Therefore, exhaustive characterisation of the energetic materials in terms of safety and rheology, coupled with characterisation of the mechanical components of the extruder, are essential for designing a safe continuous process. In this article, a technological overview of continuous processing for energetic materials is presented, along with its various features, process design methodology and safety issues.
    Źródło:
    Central European Journal of Energetic Materials; 2015, 12, 3; 507-522
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A sensitivity analysis of kinetic characterizations in continuous flotation circuits under moderate deviations with respect to perfect mixing
    Autorzy:
    Vinnett, Luis
    Pino-Muñoz, Catalina A.
    Yianatos, Juan
    Díaz, Francisco
    Henríquez, Felipe
    Powiązania:
    https://bibliotekanauki.pl/articles/2146941.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    flotation kinetics
    residence time distribution
    perfect mixing
    flotation rate distribution
    industrial flotation circuit
    Opis:
    This paper studies the effect of moderate deviations with respect to perfect mixing on the estimated kinetic parameters in industrial flotation banks. Radioactive tracer tests and mass balance surveys were performed to characterize the mixing regimes and Cu kinetic responses. For three models (Single Rate Constant, Rectangular and Gamma), two approaches to incorporate the residence time distributions (RTD) in the kinetic characterizations of rougher banks were compared: (i) RTDs measured from the radioactive tracer tests; and (ii) pure perfect mixing in each flotation machine. The measured RTDs did not present significant bypass in the evaluated banks. In all cases, comparable model fitting was obtained with both RTD approaches, which indicates that the kinetic models add sufficient flexibility to compensate for moderate biases in the mixing regime. The studied kinetic models showed non-significant differences in the estimated maximum recoveries (R∞), mean (kmean) and median (k50) rate constants when comparing the process modelling from measured RTDs and pure perfect mixing. However, the Gamma model was more sensitive to the RTD assumption in terms of the shapes of the flotation rate distributions. From the results, kinetic characterizations focused only on model fitting, or on R∞ and kmean (or k50) estimations have low sensitivity to the assumption of perfect mixing when the RTDs present moderate deviations with respect to this regime. Special attention must be paid when characterizing floating components as the perfect mixing assumption may bias the shapes of the flotation rate distributions.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2022, 58, 5; art. no. 152420
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Simulation of residence time distribution and mixing in reactors with recirculation using 2D approach
    Autorzy:
    Zima, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1934023.pdf
    Data publikacji:
    2011
    Wydawca:
    Politechnika Gdańska
    Tematy:
    mathematical modeling
    residence time distribution
    reactors with recirculation
    2D approach
    Opis:
    In this paper, we propose a 2D approach in order to create a mathematical model for the determination of the residence time distribution for a flow reactor with recirculation. Apart from characterizing the functional residence time distribution, this model can help improve the operation of the reactor at the design stage. The mathematical model was validated by comparison with experiments carried out in a hydraulic laboratory.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2011, 15, 3-4; 297-315
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Radioisotope tracer study in an indirectly heated rotary dryer
    Autorzy:
    Pant, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/147094.pdf
    Data publikacji:
    2002
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    holdup
    lanthanum-140
    mean residence time
    radioisotope tracer
    residence time distribution
    rotary dryer
    variance
    Opis:
    A radioisotope tracer study was carried-out in a pilot scale indirectly heated rotary dryer to measure residence time distribution (RTD) of sand particles. Lanthanum-140 labeled sand was used as a tracer. Mean residence time (MRT) and variance of the tracer distribution curves were calculated from the measured RTD curves. From the calculated MRTs, solid holdup in the dryer was estimated. The qualitative comparison of the dimensionless variance with the data published in the literature led to the conclusion that the rotary dryer behaves as a plug flow system. The results of the study were used to design a full-scale industrial rotary dryer.
    Źródło:
    Nukleonika; 2002, 47, 4; 173-176
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Measurement of liquid holdup and axial dispersion in trickle bed reactors using radiotracer technique
    Autorzy:
    Pant, H.
    Saroha, A.
    Nigam, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/146732.pdf
    Data publikacji:
    2000
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    axial dispersion model
    holdup
    mean residence time
    Peclet number
    residence time distribution
    trickle-bed reactor
    Opis:
    The holdup and axial dispersion of aqueous phase has been measured in trickle bed reactors as a function of liquid and gas flow rates using radioisotope tracer technique. Experiments were carried out in a glass column of inner diameter 15.2´10-2 m column for air-water system using three different types of packings i.e. non-porous glass beads, porous catalysts of tablet and extrudate shape. The range of liquid and gas flow rates used were 8.3´10-5-3.3´10-4 m3/s and 0-6.67´10-4 m3/s, respectively. Residence time distributions of liquid phase were measured and mean residence times were determined. The values of liquid holdup were calculated from the measured mean residence times. It was observed that liquid holdup increased with increase in liquid flow rates and was independent of increase in gas flow rates used in the study. Two-parameter axial dispersion model was used to simulate measured residence time distribution data and values of mean residence time and Peclet number were obtained. It was observed that values of Peclet number increases with increase in liquid flow rate for glass beads and tablets and remains almost constant for extrudates. The values of mean residence time obtained from model simulation were found to be in good agreement with the values measured experimentally.
    Źródło:
    Nukleonika; 2000, 45, 4; 235-241
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical Investigation of the Hydrodynamic Conditions in A Multi-Strand Cc Tundish with Closed Outlets
    Numeryczne badania hydrodynamiki przepływu w wielowylewowej kadzi pośredniej z zamkniętymi wylewami
    Autorzy:
    Merder, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/353484.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    numerical modeling
    residence time distribution
    tundish
    closing strand
    symulacje numeryczne
    krzywe RTD
    kadź pośrednia
    Opis:
    In industrial conditions there are situations when the CC machine works under emergency. It can be result of mechanical or electrical causes, breakout of billet or problem with supplying new parts of liquid steel to the CC machine. As a consequence one or two outlets of the tundish should be closed. However, closing one of the outlets influences the hydrodynamic and thermal conditions occurring in the tundish. Thus, the important information is which of the outlets should be closed to conduct further continuous casting process correctly. The following research was conducted to analyze the influence of liquid steel flow behaviour in the multi-strand tundish when all outlets do not work. Such problem was solved by means of numerical methods based on Navier-Stokes equations (k–ɛ standard turbulence model). Numerical simulations were done using the educational version of CFD program (Computational Fluid Dynamics) – ANSYSFluent. As a result forecasted velocity fields and RTD curves (Residence Time Distribution) were obtained. RTD characteristics were used to determine kinetics of liquid steel mixing and also to calculate parts of particular flow areas for studied cases.
    W warunkach przemysłowych zdarzają się sytuacje, kiedy maszyna COS pracuje w stanie awaryjnym. Wynikać to może z powodu usterek mechanicznych lub elektrycznych, przerwania wlewka ciągłego lub być wywołane dostarczeniem nowej partii ciekłej stali na stanowisko COS. Prowadzi to do zamknięcia jednego lub dwóch wylewów w kadzi pośredniej. Zamknięcie któregokolwiek z wylewów wpływa na warunki hydrodynamiczne i termiczne panujące wewnątrz kadzi. Istotną informacją jest więc to, które z otworów wylewowych powinny być zamknięte, aby proces ciągłego odlewania przebiegał prawidłowo. Niniejsze badania mają na celu analizę wpływu zachowania przepływu ciekłej stali w wielowylewowej kadzi pośredniej, kiedy nie pracują wszystkie otwory wylewowe. Tak postawiony problem rozwiązywano metodami numerycznymi opartymi na równaniach Naviera-Stokesa przy użyciu modelu turbulencji standard k–ɛ. Symulacje numeryczne przeprowadzono z wykorzystaniem edukacyjnej wersji programu CFD (Computational Fluid Dynamics) – ANSYSFluent. W wyniku obliczeń numerycznych otrzymano prognozowane rozkłady pól prędkości i krzywe RTD (Residence Time Distribution). Opracowane charakterystyki RTD posłużyły do określenie kinetyki mieszania stali, oraz wyliczenia udziałów poszczególnych stref przepływu dla rozpatrywanych przypadków.
    Źródło:
    Archives of Metallurgy and Materials; 2014, 59, 3; 887-892
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

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