نشریه شیمی و مهندسی شیمی ایران
سال بیست و نهم شماره 1 (پیاپی 56، بهار 1389)

In this investigation, the mean drop size and the drop size distribution which are the most important factors in the liquid-liquid dispersions were studied over a wide range of phase ratio for four different non viscous dispersed phases (namely ethyl hexanoate, toluene, kerosene and phenetole) in water. The dispersed phases have been used at concentrations of 5 to 50 (% v/v) that were agitated by Rushton turbine impeller with the revolution speed varied from 300 to 700 rpm. Drop size distributions were measured by an endoscope technique. The drop size distributions in the agitated dispersions resulted from the dynamic equilibrium existing between the breaking and coalescing drops. Since the common modulated correlation, d32(1+const)We-0.6 estimate fairy inaccurate the Sauter mean diameter especially at high hold up ratios and the linearity dependence on hold up ratio is doubtful, in frame of the classical Hinze-Kolmogorov theory, a new two-parametric relation was established which correlated the Sauter mean drop diameter to the Weber number and to the volume phase fraction much more reliably. Also, in this work the linear normal distribution function in cumulative form was used to fit the experimental data with appropriate agreement. The variations of the related standard deviation were correlated to the Sauter drop diameter and to the phase ratios. For modeling drop size distribution, the population balance equation was solved by discrete formulation methods. Drop breakage and coalescence frequency were described by famous Coulaloglou and Tavlarides model and the parameters of the model were obtained by least squares error method. The results showed that if the parameters obtained for a specified revolution speed was used the experimental and simulated data agreed well, but since the parameter depended on the power input to the system, this model should be improved.

Agglomeration rate constant or agglomeration Kernel varies by changing operating conditions such as temperature, supersaturation, seed mass, agitation speed and so on. Among affective factors mentioned, the effect of agitation speed on agglomeration Kernel has been less considered. In this work, it has been tried to investigate this effect. Experiments were done at constant temperature and different amounts of seed and agitation speed. The results were simulated and the agglomeration rate constant was extracted for each experiment. It is observed that increasing the agitation speed has no influence on agglomeration kernel at large amounts of seed, while increases it considerably at smaller amounts of seed.

In this paper, hydrodynamics of symmetric liquid-liquid jets have been numerically investigated. The simulation procedure and the VOF method of solution of the dimensionless continuity and momentum equations were explained. The predicted results from the simulation method verified the obtained experimental results for two standard liquid-liquid systems, toluene-water and butanol-water. Also the effects of dimensionless groups such as Reynolds, Froude and Weber numbers, and the ratios of the density and viscosities of phases on the dimensionless jet length and drops diameter were studied.

Pore network modeling and simulation is used to study miscible displacement in heterogeneous porous media under unsteady state conditions. The goal of this paper is to investigate the effect of pore space morphology and mobility ratio on miscible displacement processes. A two dimensional (2-D) pore network of interconnected pores with distributed effective radii is used as a model of the pore space. In this model first the flow field is solved and then the concentration distribution is determined using the convective-diffusion equation (CDE) for each pore in the network. We have considered the presence of a steady state flow of first contact miscible solvent to the network. The results show the effect of heterogeneity of the network, pore size distribution (PSD) and mobility ratio on viscous fingering formation, breakthrough time, recovery factor (RF) and longitudinal dispersion. The results of Monte Carlo simulation show that by increasing the heterogeneity of the network the fingering formation, breakthrough time and longitudinal dispersion will increase while the RF decreases. According to the results, the longitudinal dispersion depends on the network size and will increase gradually with is increase. Also the increase of the mobility ratio will decrease the break through time and increase fingering formation.

A 2-D numerical simulator for steam-assisted gravity drainage (SAGD) process is made using the model suggested by Coats et al. in MATLAB. Despite the Coats model, this extended model considers the effects of capillary and gravity in the energy equation. Also a variable thermal conductivity is used in the simulator to improve the precision of the results. At first, a sensitivity analysis is performed to investigate the process and know it better. Then, the pre-heating process is investigated using the simulator. The results show that pre-heating is necessary for a quick recovery from the reservoir. They also show that there exists an optimum duration for the preheating of each reservoir.

In this research, effective parameters of injection process such as flow rate and rock lithology, for one of Iranian giant fields, were studied under different situations, using laboratory physical model. The physical model consisted of this mentioned reservoir rock, formation fluid and injection fluid samples. Precise investigations were performed to reveal the effects of suspended particles and their movement through porous media by comparison of the results for filtrated and unfiltrated injection water. Increasing of flow rate in unconsolidated sandstones resulted in disordering of porous medium structure and creation of channels was easily observed in case of micro-fractures existence. Experimental investigation was disclosed that induced fracture in rock sample could result in injection pressure decline during first periods of injection. Unfavorably, this fracture may play the role of a channel which transfers the suspended particles or results in taking apart of particles from rock matrix. In a long period, these phenomena result in pore plugging. Plugging usually occurs in long distance form production well and in case of coming close to production well, pressure decline and consequently production reduction would be detected. Notwithstanding, for sandstone samples, significant injection pressure was not detected following by flow rate buildup, experimental observations and results showed that pore plugging and consequently permeability reduction could be distinguished as a result of particle movement through porous medium in a long distance and during extended time period.

In this research the oil drop method for preparation of spherical gamma alumina was used. An alumina hydrosol by the ratio of aluminum to chlorine 1.5, was prepared and then dispersed droplets in a vertical column of oil, the oil aged sphers are washed, aged, dried and calcinated. This spheres were sensitive to pH, temperature and moisture. So the operation parameters were modified and the produced spherical activated alumina was proper to become a catalyst support.

In this study, the effective moisture diffusivity, density and shrinkage of a cylindrical solid particle in a fluidized bed dryer (FBD) containing inert particles and assisted by infrared (IR) heat source are investigated. For this purpose a pilot-scaled apparatus was onstricted and drying experiments were carried out at different operating conditions of inlet air temperature, inlet air velocity, weight of inert particles, drying particle diameter and infrared power input. The apparatus consists of a fluidized bed dryer of inert particles using hot air with and without infrared heat source. Cylindrical pieces of potato were used as drying sample. The results showed that the effective moisture diffusivity in potato was a function of temperature and moisture content while the shrinkage and density are function of moisture content only. Some empirical correlations were given for the effective moisture content, shrinkage and density. Comparison of the results obtained for the shrinkage with and without IR heat source showed a less shrinkage of drying particle when IR heat source is used. This last effect which could be due to the formation of a crust around the drying particle is very attractive to food industries.

In this study, Cetyl Pyridinum Chloride (CPC) as a model surfactant and -amylase as a new structure ordering agent was used in preparation of porous silica using sol-gel method and their effect in porosity creating and structure ordering compared with each other and with silica witch synthesized in lake of template. Usefulness of new template is leading to the large inter-particle and structural porosity which first on facilitates transport phenomena and the second leads to suitable support for immobilization of large particles of catalysts such as enzymes. Synthesized supports using templates (CPC and enzyme), contrary to silica witch synthesized without template, was more regular and had higher specific surface area. In spite of lower specific surface area of new support in compare to CPC-templated silica (720 vs. 900 m2/g), initial tests showed that the new support is more suitable for immobilization of large molecules such as -amylase and enzyme loading in new support was more than about 1.4 times.

In this study nitrification rate of activated sludge of Tabriz oil refinery was investigated via respirometry and direct measurement by ammonium electrode. Applied respirometric set-up was closed respirometer with static gas-static liquid. On direct measurement method an ammonium electrode was applied. Experiments showed appropriate reproducibility as coefficients of variation of results were small on both methods. Value of achieved mean nitrification rate with respirometery, 0.408mgN/gMLSS.h, was higher than the calculated value of nitrification rate with direct measurement by ammonium electrode. Interference of some ions as nitrite and nitrate on ammonium electrode measurements, short period of measurements time on respirometric experiments and identification ability of nitrite oxidation rate to nitrate, were the main parameters that highlighted respirometric method as a more reliable and faster method.

Paper recycling industry have been propounded as need due to some economical and environmental reasons. In this study, we aimed recycling of printed wastepaper to produce recycling paper. In order to eliminate ink from wastepaper, we used flotation as deinking method.In this study physical properties of hand sheets such as grammage, thickness, density, and bulk were studied. The maximum and minimum rates of density related to A and C samples respectively. With decreasing of freeness resistance to bursting and tensile of hand sheets were increased. Also, with decreasing of freeness the rate of tear was decreased. The maximum rate of strength to bursting were observed in freeness 384 milliliter (ml), also, the maximum rate of strength to tearing was in freeness 490 ml. Maximum and minimum rates of deinking yield, were in ratios of 3 to 2 and 1 to 2 of (H2O2: NaOH), respectively.

Bis (2-ethylhexyl) phosphoric acid is one of the acid and surfactant compounds that are a useful range of industrial product. Pure Bis (2-ethylhexyl) phosphoric acid compound is common used in hydrometallurgy. In this study, through a stiff reaction of Phosphorous pentoxide and 2-ethylhexanol we prepared a mixture of mono- and bis (2-ethylhexyl) phosphoric acid compounds with a partial phosphoric acid. Because of special structure of the anhydride phosphoric and base on different reaction temperatures and molar ratios of reactants, variety proportions of mono- and diester with small amount of triester and free alcohol were achieved. Equal proportions of mono and diester with 1 to 3 molar proportions of phosphor pentaoxide and 2-ethylhexanol were prepared at 70 ºc and 7 hr. Such results suggest that ratio of mono- and di ester is due to a reaction conditions like time, molar ratio and temperature. In this research high percentage of bis (2-ethylhexyl) phosphoric acid compound is obtained that after purification and separation it was characterized by FT-IR, 1HNMR and 31P-NMR.