Iranian Journal of Chemistry and Chemical Engineering
Volume:28 Issue: 3, May-Jun 2009

Block heights and capillary continuity between matrix blocks play paramount role in the sensitivity analysis and therefore the history matching of cumulative oil production and production rate of carbonated fractured reservoirs. In this study, the influence of these parameters upon cumulative production and recovery factor of an Iranian fractured reservoir were studied by the usage of a simulator. Results show that, changing the block heights greatly affect on the cumulative production as well as the recovery factor. Also sensitivity analysis reveals that, the variations in cumulative production and recovery factor happen in a limited range of block heights. The aforementioned ranges of block heights for the studied reservoir were twice the height and one tenth of the height of the block height used in the history matching during the reservoir simulation. For block heights shorter than the original one, the influence of capillary continuity is paramount by increasing the cumulative production as well as the recovery factor. However, as the block height increased and reached twice the height of the original height, the influence of capillary continuity decreased and the system behaved similar to the situation where the block height was doubled without taking capillary continuity into consideration.

The aim of the present work is to prepare an adsorption package to simulate adsorption / desorption operation for both single and multi-component systems in an isothermal condition by different mechanisms such as; local adsorption theory and mass transfer resistance (rigorous and approximated methods). Different mass transfer resistance mechanisms of pore, solid and bidispersed diffusion, together with nonlinear isotherms (Longmuir, Frendlich, Sips and Toth) are taken into account in modeling the fixed bed adsorbers. The Extended Longmuir isotherm was found to explain properly the binary and ternary mixtures in adsorption/desorption process. Almost all the mass transfer approximations were explained by the linear driving force, LDF, although the alternative driving force, ADF, approximation was examined in some cases. The numerical solution was the Implicit Method of Lines which converted the partial differential equations to the ODEs then solving them by the Runge-Kutta method. Validation of the models was performed by the experimental data derived from the literature for different types of adsorbents and adsorbates. The sensitivity analyses was carried out to find out variation of the breakthrough curves against some physical and operational parameters such as; temperature, flow rate, initial and inlet concentration and particle adsorbent size. The results revealed excellent agreement of simulated and previously published experimental data.

Plackett-Burman design was used for selection of important media components such as carbon and nitrogen sources and minerals which affect poly(hydroxybutyrate) production and cell growth of Methylobacterium extorquens DSMZ 1340. Among the studied variables, nitrogen and phosphorus sources, MgSO4 and most of the trace elements were found to be significant variables for PHB production from methanol. At best condition (based on PHB concentration), dry cell weight, PHB content and PHB concentration were 3.81 g/L, 21.23 %, and 0.809 g/L, respectively. It was also found that most of the trace elements and phosphorus sources were influential parameters on the growth of microorganism but the kind of nitrogen source was not. The experimental results showed that deficiencies of nitrogen sources (NH4Cl and NH4NO3), phosphorus sources (K2HPO4 and Na2HPO4) and MgSO4 in medium, increased PHB accumulation.

Polycyclic aromatic hydrocarbons are a class of potentially hazardous chemicals of environmental and health concern. PAHs are one of the most prevalent groups of contaminants found in soil. Biodegradation of complex hydrocarbon usually requires the cooperation of more than single specie. In this research biotreatment of PAH (phenanthrene) was studied in a solid-phase reactor using indigenous bacteria isolated from two petroleum contaminated sites in Iran, (i.e., Tehran refinery site with clayey-sand soil composition and Bushehr oil zone with silty-sand soil composotion). Phenanthrene (C14H10) was made in three rates (100, 500, and 1000 mg/kg of soil) synthetically and was conducted with two bacterial mixed cultures for a period of 20 weeks. Highest removal (more than 85 %) of phenanthrene with rates of 100, 500 and 1000 mg/kg in clayey-sand soil with BMTRS (Bacterial Mix of Tehran Refinery Site) consortium was achieved within 3, 5 and 14 weeks, respectively as for silty-sand soil composition with BMBOZ (Bacterial Mix of Bushehr Oil Zone) consortium was achieved within 10, 17, and 19 weeks, respectively. Results for phenanthrene biotreatment in solid phase reactor revealed a significance relationship between concentration and type of microbial consortium with the removal efficiency of phenanthrene over the time (P value<0.001). Furthermore, there was a significant relationship between soil type with removal efficiency of phenanthrene over the time (P value=0.022). That means the bioremediation of the lower concentrations of phenanthrene needs shorter time compared with the higher concentrations. Microbial analysis using confirmative series tests and analytical profile index (API) kit tests showed the Pseudomonas fluorescence, Serratia liquefaciens, Bacillus and Micrococcus strains as dominant bacteria in the mixed cultures.

Simulation of turbulence boiling, generation of vapour and predication of its behaviour are still subject to debate in the two-phase flow area and they receive a high level of worldwide attention. In this study, a new arrangement of the three dimensional governing equations for turbulence two-phase flow with heat and mass transfer are derived by using ensemble averaging two-fluid model and utilizing the latest approved constitutive equations. Then, the governing equations are simplified for bulk boiling in a vertical channel. A computer program with SIMPLE algorithm is written for the simplified equations, and the results are compared with available experimental data and a boiling water reactor in operating condition.

Genetic programming (GP) is one of the computer algorithms in the family of evolutionary-computational methods, which have been shown to provide reliable solutions to complex optimization problems. The genetic programming under discussion in this work relies on tree-like building blocks, and thus supports process modeling with varying structure. In this paper the systems containing amino acids + water + one electrolyte (NaCl, KCl, NaBr, KBr) are modeled by GP that can predict the mean ionic activity coefficient ratio of electrolytes in presence and in absence of amino acid in different mixtures better than the common polynomial equations proposed for this kind of predictions. A set of 750 data points was used for model training and the remaining 105 data points were used for model validation. The root mean square deviation (RMSD) of the designed GP model in prediction of the mean ionic activity coefficient ratio of electrolytes is less than 0.0394 and proves the effectiveness of the GP in correlation and prediction of activity coefficients in the studied mixtures.

In this study chitosan hydrogel beads with porosity ~ 0.86 and diameter ~ 2 0.07 mm were prepared from 85 % deacetylated chitosan for removal of Cd 2+ ions from aqueous solutions. Chitosan powder was dissolved into dilute acetic acid as solvent and formed into spherical beads using a phase inversion technique. The effect of temperature, initial concentration of Cd 2+ ions, and the period of agitation were perused to achieve the best isotherm model. Freundlich model was better fitted than Langmuir model (R2 > 0.99 and R2> 0.93 respectively, at pH of 6.3, and shaker speed of 200 rpm), the constants of Langmuir and Freundlich models were calculated, which RL value and qmax (mg/g wet weight) at 30 °C, 40 °C, 50 °C showed maximum uptake capacity of 61.35 (mg/g wet weight) obtained at 30 °C. The calculated heat of adsorption was -8.69,-7.051, -5.513 kJ mol -1 at 30, 40, 50 °C respectively which verified an exothermic process. Kinetic studies of the adsorption phenomena were conducted in a batch system by initial concentrations from 100 to 500 mgL-1 until the equilibrium concentration Ce (mgL-1) was reached. First-order, and second-order kinetic models were used; the experimental data were in reliable compliance with second-order kinetic model with R2 value greater than 0.97. The rate constants of the kinetic models were also calculated and tabulated. To investigate the surface morphology of the chitosan beads before and after adsorption process, they were observed by the use of Scanning Electron Microscopy (SEM). The surface characterization of the beads in both cases showed metal ions binding toward the surface of porous chitosan beads. All of the experiments carried out at pH of 6.3 and agitation rate of 200 rpm, which were opted according to optimum status of previous researcher’s reports

Phase inversion in liquid-liquid dispersions corresponds to the transitional boundary between Oil-in-Aqueous dispersion and Aqueous-in-Oil dispersion. A theoretical model based on simple assumptions was proposed to predict phase inversion point, ambivalence region and the hysteresis effect of inversion. Experimental data from the literature were used to validate the model and results were compared with those obtained by the Yeo et al. model. Comparison shows that there is a reasonable agreement between the suggested model and the experimental results taken from the literature. It is also pointed out that this model generates smaller relative errors than the previous work of Yeo et al. does.

Abstract: A mathematical model for commercial naphtha catalytic reformer of Tehran refinery was developed. This model includes three sequencing fixed beds of Pt/Al2O3 catalyst at the steady state condition using detailed kinetic scheme involving 26 pseudo-components connected by a network of 47 reactions, in the range of C6 to C9 hydrocarbons. The reaction network consisted dehydrogenation, hydrogenation, ring expansion, paraffin and iso-paraffin cracking, naphthene cracking, paraffin isomerization and hydrodealkylation of aromatics. The kinetic model was fine tuned against industrial plant data using a feed characterized by PIONA (Paraffin, Iso-paraffin, Oleffin, Naphthene and Aromatics) analysis. The final outlet results of the reformer such as RON (Research Octane Number), yield and outlet reformate compositions have shown good agreement with actual conditions of Tehran Refinery reforming unit

Recovery of metabolites from fermentation broth by solvent extraction can be used to optimize fermentation processes. End-product reutilization, low product concentration and large volumes of fermentation broth and the requirements for large bioreactors, in addition to the high cost largely contributed to the decline in fermentative 2,3-butanediol production. Extraction can successfully be used for in-situ alcohol recovery in 2,3-butanediol fermentations to increase the substrate conversion. In the present work organic extraction of 2,3-butanediol produced by Klebsiella pneumoniae fermentation was studied to determine solvent effect on 2,3-butanediol production. The aim of this project was liquid-liquid extractive fermentation systems evaluation as an alternative to overcome the end product effect and to increase of 2,3-butanediol production by K.pneumoniae because Conventional fermentative production of 2,3-butanediol by K. pneumoniae has the disadvantage of product reutilization by the organism. Alternatives to overcome this problem have met with limited success. Extractive fermentation has been shown to solve this problem. An effort has been made in this study to use for the extractive fermentation of 2,3-butanediol using oleyl alcohol as extract-ant. Eighteen organic solvents were examined to determine their biocompatibility for in situ extraction of fermentation products from cultures of the K. pneumoniae. From 18 tested solvents, 13 of which were non-toxic to K.pneumoniae. The highest 2,3-butanediol production (23.01 g l-1) was achieved when oleyl alcohol was used. In situ removal of end products from K.pneumoniae resulted in increased productivity. In conclusion 2,3-butanediol productivity increased from 0.5 g l-1h-1 to 0.66 g l-1h-1 in extractive fermentation using oleyl alcohol as the extraction solvent.