Temat: Kinetics - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Experimental determination of the kinetics of sorption and gas filtration in coal
Autorzy:: Gawor, M.
Tematy:: sorption
filtration
sorption kinetics
filtration kinetics; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/178925.pdf Link otwiera się w nowym oknie
Opis:: The paper presents tests set-ups for experiments on sorption kinetics and gas filtration kinetics in a porous medium. It was observed that two phenomena occur in these processes: transportation of gas into the porous solid and settling of gas molecules on the walls of the solid or within its volume. An experiment was carried out in which a thin resistance thermometer was quickly taken out of an argon stream and placed in carbon dioxide or the other way round. The measurement made it possible to determine the sorption time constant. It was demonstrated that the sorption rate is much higher than the filtration rate. Thus, filtration is the process describing the rate at which gas molecules penetrating the porous substance are adsorbed or desorbed. The sorption time constant is not >50 m. In the second experiment, the author determined the rate at which gas is liberated from coal grains. The measurement method was based on measurement of the pressure of desorbing gas in constant volume. The experiment involved measurement of the pressure of the gas liberated from the coal grains in a closed chamber. The kinetic curves obtained in this way were used to determine the carbon dioxide coefficient in coal grains. During the experiment, particular focus was put on the initial stage of gas liberation (up to 0.4 s). The slower process of gas transporting in the porous structure of coal is the transporting of gas through a coal briquette. Experimentally implemented variety of boundary conditions allowed for a more complete verification of the assumed theoretical model and possibly for the exact determination of filtration parameters. The experimental set-up built for this purpose, allows for pressure and temperature measurement on the briquette side surface.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Kinetics of drying of carrots in an industrial pentabelt dryer
Autorzy:: Domagala, A.
Witulska, M.
Janus, P.
Tematy:: drying kinetics
carrot
drying
food technology
kinetics
drying curve
drying rate
plant; Pokaż więcej
Wydawca:: Instytut Rozrodu Zwierząt i Badań Żywności Polskiej Akademii Nauk w Olsztynie
Powiązania:: https://bibliotekanauki.pl/articles/1372595.pdf Link otwiera się w nowym oknie
Opis:: The kinetics of drying of carrot cubes (10 mm and 14 mm) and slices (3 mm thick, 18.4-41.5 mm diameter) in an industrial pentabelt dryer was investigated. The temperature of drying air supplied under the first and second belts of the dryer was 90°C and it was 60°C for the other belts. The carrot was dried to a final moisture content of 0.1 kg/kg (9.09%). The drying curve, u = f(ԏ), and drying rate curve, du/dԏ = f(u) were determined and described with the equations. The times of the constant drying rate period were 60 min and 82 min for the 10 mm and 14 mm cubes, respectively, and 94 min for the slices. The respective total drying times were 305 min, 350 min and 250 min.
Głównym celem pracy było przeanalizowanie kinetyki suszenia marchwi w pięciotaśmowej suszarce z przenośnikami taśmowymi usytuowanymi jeden nad drugim (rys. 1), ze szczególnym uwzględnieniem jakości suszu. Analizy tej dokonano na podstawie sporządzonych krzywych suszenia u=f(ԏ) (rys. 2) i szybkości suszenia du/dԏ=f(u) (rys. 3). Materiałem doświadczalnym były plastry marchwi o grubości 3 mm oraz kostki (sześciany) o bokach 10 i 14 mm. Temperatura czynnika suszącego doprowadzonego pod pierwszy i drugi przenośnik taśmowy wynosiła 90°C, a temperatura czynnika suszącego pod pozostałymi przenośnikami była równa 60°C (tab. 1). Krajankę marchwi suszono do wilgotności właściwej (u) równej 0,1 kg/k g (tab. 2). Krzywe suszenia opisano równaniami szczegółowymi, umożliwiającymi obliczenie czasu suszenia (ԏ) dla dowolnej wilgotności właściwej (U2) w drugim okresie suszenia. Całkowite czasy suszenia, obliczone według tych równań, różnią się od całkowitych zmierzonych czasów suszenia najwyżej o 6 minut, co stanowi zaledwie 1,7% (tab. 3). Strata sumy karotenoidów na skutek suszenia krajanki marchwi wynosiła od 3,46 do 5,07%, ocena organoleptyczna suszu stanowiła ponad 4,0 punkty, a średnia zdolność chłonięcia wody przez susz wynosiła 4,3 (tab. 4). Na. podstawie przeprowadzonych badań wnioskuje się, że dobre wskaźniki jakości suszu jak na warunki przemysłowe, można uzyskać jedynie przez sterowanie procesem suszenia na podstawie doświadczalnie wyznaczonych krzywych suszenia.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Examination of steam gasification of coal with physically mixed catalysts
Autorzy:: Śpiewak, Katarzyna
Czerski, Grzegorz
Sopata, Agnieszka
Tematy:: coal gasification
kinetics
catalysts; Pokaż więcej
Wydawca:: Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Powiązania:: https://bibliotekanauki.pl/articles/779131.pdf Link otwiera się w nowym oknie
Opis:: The aim of this study was to analyse the steam gasification process of ‘Janina’ coal with and without Na-, K- and Ca-catalysts. The catalysts were physically mixed with the coal due to the simplicity of this method, short time of execution and certainty that the amount of catalyst is exactly as the adopted one. The isothermal measurements were performed at 800, 900 and 950°C and a pressure of 1 MPa using thermovolumetric method. The obtained results enabled assessment of the effect of analysed catalysts on the process at various temperatures by determination of: i) carbon conversion degree; ii) yield and composition of the resulting gas; and iii) kinetics of formation reactions of main gas components – CO and H₂. The addition of catalysts, as well as an increase in operating temperature, had a positive effect on the coal gasification process – reactions rates increased, and the process time was reduced.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Mechanism and kinetics of pyrite transformation at elevated temperatures
Autorzy:: Aracena, Alvaro
Jerez, Oscar
Tematy:: pyrite
pyrrhotite
roasting
kinetics; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/2146885.pdf Link otwiera się w nowym oknie
Opis:: Pyrite (FeS2) is known as a sulfide that provides energy for various pyrometallurgical processes (fusion and conversion). There are several studies related to the evaluation of pyrite oxidation mechanisms at high temperatures, obtaining discrepancies in the products generated. In our work, the novelty of our research would be to obtain the thermochemical oxidation mechanism of FeS2 by using conventional thermogravimetric methods. The oxidative roasting of pyrite from 550 to 800°C was analyzed for an oxygen concentration of 5.07 to 28.06 kPa of oxygen and particle size between 12.3 to 33.8 microns. The results showed that the pyrite proceeded by sequential roasting: first, it produced an intermediate compound, pyrrhotite (Fe7S8), which was later oxidized to generate hematite (Fe2O3), both stages validated by weight loss of the sample as well as by analysis by DRX. Each stage had a different roasting speed as it was also influenced differently by different parameters. The temperature and particle size favored the rate of pyrrhotite generation, and the oxygen concentration favored the rate of hematite formation. The first-order kinetic equation ln (1-XPy) represented the roasting of the first stage (FeS2 → Fe7S8), with a calculated activation energy of 70.1 kJ/mol. The order of reaction was 0.5 concerning the partial pressure of oxygen and inversely proportional to the initial particle radius.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Modelling of interacting dimer adsorption
Autorzy:: Barbasz, Jakub
Cieśla, Michał
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 6.

Tytuł:: How to avoid mass transfer limitations in ozonation kinetics of phenylphenol isomers?
Autorzy:: Olak-Kucharczyk, M.
Ledakowicz, S.
Tematy:: phenylphenol isomers
ozonation in homogenous system ozonation kinetics
competition kinetics
classical kinetics
ozonowanie w jednorodnym systemem kinetyki ozonowania
kinetyka konkurencji
kinetyka; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:: https://bibliotekanauki.pl/articles/185599.pdf Link otwiera się w nowym oknie
Opis:: Ozonation is a heterogeneous process of chemical absorption often controlled by a gas-liquid mass transfer rate. This paper presents the results of kinetics in a reaction between phenylphenol isomers and ozone. The degradation of phenylphenol isomers during ozonation proceeds quite fast. In order to avoid the influence of mass transfer limitati on the kinetics experiments were conducted in a homogenous liquid-liquid system. The second-order rate constantswere determined using classical and competition methods, which are especially recommended for fast reactions. The determined rate constants at pH 2 using the two different methods are almost the same. The increase of pH causes an increase of rate constants for the reaction of phenylphenol isomers with ozone.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Slow $\dot{V}o_{2}$ off-kinetics in skeletal muscle is associated with fast PCr off-kinetics-and inversely
Autorzy:: Korzeniewski, Bernard
Żołądź, Jerzy A.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 8.

Tytuł:: Kinetics of uranyl ion polymerization in the presence of ammonium hydroxide
Autorzy:: Abdelrazek, I.
Zidan, W.
Farag, H.
Barakat, M.
Tematy:: uranyl ion
hydrolysis
kinetics
polymerization; Pokaż więcej
Wydawca:: Instytut Chemii i Techniki Jądrowej
Powiązania:: https://bibliotekanauki.pl/articles/148783.pdf Link otwiera się w nowym oknie
Opis:: Kinetics of the polymerization of UO2 2+ ion to UO2[(OH)2UO2]4 2+ in the ammonia-uranyl nitrate system has been studied. The deepening of the color formed with the addition of ammonia made it possible to estimate spectrophotometrically the concentration of the formed UO2[(OH)2UO2]4 2+ ions in the solution at 420.6 nm. The effects of pH, temperature as well as the concentration of uranyl ion have been investigated. The reaction rate equation for the polymerization reaction is presented. Linear dependencies of logarithm of the apparent reaction-rate constant on both pH and the reverse of temperature were observed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Adsorption Kinetics of Reactive Dyes on Ash from Town Heating Plant
Autorzy:: Djordjevic, D.
Stojiljkovic, D.
Smelcerovic, M.
Tematy:: kinetics
reactive dye
adsorption
ashes; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/205104.pdf Link otwiera się w nowym oknie
Opis:: In order to investigate the mechanism of adsorption of reactive dyes from the textile industry on ash from heating plant produced by brown coal combustion, some characteristic sorption constants are determined using Langergren adsorption equations for pseudo-ﬁrst and pseudo-second order. Combined kinetic models of pseudo-ﬁrst order and pseudo-second order can provide a simple but satisfactory explanation of the adsorption process for a reactive dye. According to the characteristic diagrams and results of adsorption kinetic parameters of reactive dyes on ashes, for the applied amounts of the adsorbents and different initial dye concentrations, it can be concluded that the rate of sorption is fully functionally described by second order adsorption model. According to the results, the rate constant of pseudo-second order decreases with increasing initial dye concentration and increases with increasing amount of adsorbent – ash.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Application of leaching kinetics modelling to a gold cyanide leach plant by using real plant data
Autorzy:: Sayiner, B.
Tematy:: gold
cyanide
leach
kinetics
model; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/109738.pdf Link otwiera się w nowym oknie
Opis:: Gold cyanide leach kinetics modeling was applied to the Bergama Ovacik gold cyanide leach plant in Turkey by processing the real plant data without need of any laboratory work. For this aim, solid ore samples were taken from each leaching tanks and analysed for gold contents as Au ppm while plant variables such as solid % concentrations in each tank, feed rate of plant as megagrams per hour (Mg/h), slurry flow rate as m3/h and the slurry residence times in each tank calculated and noted for modelling study. Five sampling work performed at plant at different times. Each sampling data were modelled seperately by the Anglo-American Research Laboratories (AARL) leach kinetics model to obtain five seperate model parameters and regression coefficient (R2) values. Then, total five sampling data were all together modelled to obtain just one model equation and R2 value to represent the plant generally. All R2 values were above 0.90 indicating that the AARL gold leaching kinetics model fits well on real plant leaching conditions. By using the model parameters, the residual gold contents in each tank were predicted for different possible ore feed rate tonnages such as 80, 90, 100, 110 and 120 megagrams per hour. Thus, leaching recoveries for any ore feed rate would be estimated for possible tonnage increases in the future.
Dostawca treści:: Biblioteka Nauki

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