A 4-lump kinetic model including hydrogen consumption for hydrocracking of vacuum gas oil in a pilot scale reactor is proposed. The advantage of this work over the previous ones is consideration of hydrogen consumption, imposed by converting vacuum gas oil to light products, which is implemented in the kinetic model by a quadratic expression as similar as response surface modeling. This approach considers vacuum gas oil (VGO) and unconverted oil as one lump whilst others are distillate, naphtha and gas. The pilot reactor bed is divided into hydrotreating and hydrocracking sections which are loaded with different types of catalysts. The aim of this paper is modeling the hydrocracking section, but the effect of hydrotreating is considered on the boundary condition of the hydrocracking part. The hydrocracking bed is considered as a plug flow reactor and it is modeled by the cellular network approach. Initially, a kinetic network with twelve coefficients and six paths is considered. But following evaluation using measured data and order of magnitude analysis, the three route passes and one activation energy coefficient are omitted; thus the number of coefficients is reduced to five. This approach improves the average absolute deviation of prediction from 7.2% to 5.92%. Furthermore, the model can predict the hydrogen consumption for hydrocracking with average absolute deviation about 8.59% in comparison to those calculated from experimental data.
Coating thickness protection in the burning zone of a rotary cement kiln during operation is important from the viewpoint of the kiln productivity. In this paper, an integrated model is presented to estimate the coating thickness in the burning zone of a rotary cement kiln by using measured process variables and scanned shell temperature. The model can simulate the variations of the system, thus the impact of different process variables and environmental conditions on the coating thickness can be analysed. The presented steady-state model derived from heat and mass balance equations uses a plug flame model for simulation of gas and/or fuel oil burning. Moreover, the heat transfer value from shell to the outside is improved by a quasi-dynamic method. Therefore, at first, the model predicts the inside temperature profile along the kiln, then by considering two resistant nodes between temperatures of the inside and outside, the latter measured by shell scanner, it estimates the formed coating thickness in the burning zone. The estimation of the model was studied for three measured data sets taken from a modern commercial cement kiln. The results confirm that the average absolute error for estimating the coating thickness for the cases 1, 2, and 3 are 3.26, 2.82, and 2.21 cm, respectively.La protection de l'épaisseur du revêtement dans la zone de combustion d'un séchoir rotatif pour cimenterie pendant le fonctionnement est importante du point de vue de la productivité du séchoir. Dans ce document, un modèle intégré est présenté pour estimer l'épaisseur du revêtement de la zone de combustion d'un séchoir rotatif pour cimenterie en utilisant des variables de fonctionnement et des mesures de la température de l'enveloppe. Le modèle peut simuler les variations du système; par conséquent, on peut analyser les conséquences des différentes variables de fonctionnement et conditions environnementales sur l'épaisseur du revêtement. Le modèle en régime permanent présenté, dérivé deséquations de bilan de masse et d'énergie, fait usage d'un modèle de flamme enécoulement piston pour la simulation de la combustion de gaz ou de mazout. De plus, le transfert de chaleur de l'enveloppeà l'extérieur est amélioré par une méthode quasi dynamique. Par conséquent, en premier lieu, le modèle prédit le profil de la température intérieure tout au long du séchoir, puis en considérant la différence entre les températures intérieures et extérieures, mesurées par balayeur, l'épaisseur du revêtement formé est estimée sur le plan local. La prédiction du modèle est examinée par trois ensembles de données qui proviennent d'un séchoir pour cimenterie commercial moderne. Les résultats confirment que l'erreur absolue moyenne pour estimer l'épaisseur de revêtement pour les cas 1, 2 et 3 sont 3,26, 2,82 et 2,21 cm, respectivement.
Producing transportation fuels from bio sources was of prime importance due to the strict environmental legislations for producing clean fuels from conventional oil resources. However, the economical impacts of the biofuel production should be considered. In this study, the production of bio-naphtha and biodiesel from palm oil using homogeneous catalyst, i.e. an aqueous phase of ammonium molybdate, was studied. This catalyst was prepared by dissolving sodium molybdate in de-ionized water with hydrochloric acid, and then neutralizing the mixture with ammonium hydroxide. The solution was dried at 90 °C for 24 h to obtain ammonium molybdate. Then, characterization of the catalyst was done by informative techniques, such as XRD and FT-IR. The results showed that the main phase of the synthesized catalyst was molybdate ammonium hydrates (4MoO3.2NH3.H2O), and also bands of Mo-O, Mo-O-Mo, N-H and surface hydroxyl groups were observed in the sample. Moreover, activity test confirms that the bio-naphtha produced from the proposed method has a few aromatic components, and its sulfur content was negligible. Moreover, ash, nitrogen, sulfur and carbon residue were not detected in the produced biodiesel, and its Cetane index was 66.3. Therefore, it was a suitable fuel for diesel engines vehicles.
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