Sharif Digital Repository

Uranium is one of the most important elements in nuclear fuel cycle. Recovery of uranium from wastes that were generated in varrious prosesses of nuclear fuel cycle, is very important not only because of economical values, but also due to their envirolmental. A considerable amount of solid waste have been produced during the fluorination process of in fluorination fludizedbed reactor at UCF plant in Iran. In this thesis, first, the solid waste of UCF floinatin reactor has been characterized. After characterization of waste, the dissolution of waste by different solvents has been studied and optimom condition for dissolution was determinated. Uranium recovery from the solution was tested... 

In this research, a mathematical model was developed to simulate a two-phase fluidized bed reactor for oxidative dehydrogenation of propane to propylene. Since the assumption of minimum fluidization condition for the emulsion phase is not realistic , the hydrodynamic structure proposed by Cui et al. was used in this study. The mass balances in unsteady state was obtained in a control volume. The differential equations contain three terms, corresponding to the mass transfer by convection, the exchange between phases and the reaction. All differential equations based upon material balances, hydrodynamics and kinetics for all components were solved numerically using MATLAB software 2010a.... 

In this study, four parameters were investigated including temperature, inlet flow rate, gas composition (oxygen) and particle size on the roasting of Bama company zinc sulfide concentrate in Fluidized bed reactor. Initially, primary sample was heated in electric furnace at 125℃ for 24 hours until the moisture content dried. Then roasting operation was done at 700 and 900℃. The operation was carried out on three range of particle size including 300-500, 500-700 and 700-1000 microns and flow rate was greater than the minimum flow rate of Fluencing. To investigate the effect of flow rate and gas composition input, 500-700 micron particle size range was selected. The effect of 155, 172 and 188... 

In this study effect of air flow rate, particle size and oxygen excess on roasting of copper concentrate in a fluidized bed reactor were investigated. Copper concentrate in this work was from sarcheshme copper mine. For determination of the weight percentage of remaining sulfur, calcins were analyzed by XRD. The effect of air flow rate was studied at 211,250 and 312 lit/min. The results indicate that an increase in air flow rate led to a decrease in amount of sulfur in the calcin. For study the effect of oxygen excess roasting were done with 20,21 and 23 volume percent of oxygen and the results were the same as the effect of air flow rate. For study the effect of particle size, roasting were... 

Catalytic cracking is one of the most important unit and process of catalytic processes in the world that transforms heavy and cheap oil materials to lighter and valuable materials. Nowadays due to global increase in fuel consumption and the need to transform heavy materials to lighter ones there is an increasing attention and need to this process.
This system consists of two main sections. Riser reactor and regenerator to burn the Coke that is accumulated on the catalyst which in this project we tend to simulate the riser reactor of FCC unit of Abadan refinery in which the cracking is done. The considered kinetic model, is a three-lump model that is able to predict the conversion... 

In this study designing and manufacturing of high-temperature fluidized bed reactor were performed. These reactors are based on the contact of fluid with solid particles and balancing the weight of the solid materials. In the manufactured reactor, reduction of manganese de oxide to manganese oxide was done by carbon monoxide produced from incomplete combustion. The most important parameters in the reduction rate are: bed temperature and reduction gas concentration. Materials were injected into the reactor under the pressure of 1.13 mmHg and temperature of 787 ℃ in the bed depth of 4 cm for 2 hours and then the product was removed. XRD patterns showed that the dominant phase in the product... 

The Effects of temperature, residence time and particle size has been investigated on partial reduction of hematite to magnetite VIA fluidized bed reactor. Since there is water crisis in Iran, it is not rational to use gravity separation processes. Rather the best way is to use magnetic separation. Ghazvin’s region non-coking coal was used for gasifying step in various temperatures in order to produce the gas reduction agent. Golgohr’s mine waste concentrate were tested as the initial iron ore. For the very first time, the residence time of the particles were investigated by the change of height of reaction chamber, in 3 different heights, and the highest i.e. 15 cm had the best results. As... 

In this thesis the perovskite catalyst of La0.7Sr0.3FeO3 with different percentages of kaolin and alumina boehmite as binders was synthesized to be used in the chemical looping partial oxidation process. To determine the best catalyst in terms of resistance against attrition, an attrition test was performed in a jet cup testing rig. The best catalyst in terms of resistance against attrition was perovskite catalyst 60% weight,25% weight kaolin and 15% weight alumina beohmite. Cold test of fluidized bed of the optimum catalyst in terms of resistance against attrition performed and minimum fluidization velocity, terminal velocity, flow regime type and Geldart type was obtained. The synthesized... 

The purpose of this study is the simulation of Printed Circuit Board’s thermal decomposition process based on the latest updated environmentally safe methods, to produce valuable materials. The method used is an efficient process for recycling printed circuits to prevent harmful environmental consequences of inadequate methods, and also to obtain a small amount of fuel for recycling. In this research, the pyrolysis process of printed circuits has been simulated using Aspen Plus software. In the simulation, a fluidized bed is used as a pyrolysis reactor and also a combination of two mechanisms is used to determine the kinetics and reactions in the reactor. The desired product in this process... 

Hydrodynamic behavior of gas-solid fluidization in large-diameter beds like FCC regenerator exhibits complex aspects. To investigate the gas-solid flow pattern of UOP's combustor-style FCC regenerator, a lab-scale regenerator was designed by a downscale factor of 0.045. The regenerator's operation and fluidization of FCC particles through it was examined and pressure axial distributions were measured and analyzed at different superficial air velocities. 3D CFD simulation of the regenerator was performed with Eulerian-Eulerian approach to investigate the effects of operating conditions, including superficial air velocity, catalyst mass flux, presence of recirculated catalyst, and the...