فهرست مطالب jafari behbahani

In this work, the influence of substituted fullerene on the pour point and rheological behavior of a waxy crude oil sample was investigated. The compositional analysis of crude oil was performed and then the influence of the substituted fullerene on the viscosity and pour point of waxy crude oil was evaluated. The results show that the substituted fullerene reduces the pour point of the waxy crude oil is in all concentrations. Also, the results indicate that viscosity reduces by increasing the concentration of substituted fullerene at constant temperature and shear stress. While viscosity increases by decreasing the temperature of crude oil. It is obvious that by increasing the shear rate the viscosity decreases dramatically. Results show that the shear rate has considerable effect on decreasing viscosity particularly at temperatures below the pour point.

Asphaltene precipitation may occur during pressure depletion or gas injection processes in a reservoir. This phenomenon is an important problem during oil production, because it can result in formation damage and the plugging of wellbore and surface facilities. In this work, the precipitation of asphaltenes in an Iranian crude oil, under different pressures, is measured, using an experimental set up based on high-pressure isothermal expansion and also atmospheric titration. For the particular oil investigated, compositional data, precipitation phase diagrams, and bubble point and onset pressures are reported. Also, in this work, the Perturbed Chain form of the Statistical Associating Fluid Theory (PC-SAFT), the Solid model and the Flory-Huggins model are used, to correlate onset pressures and solvent ratios at the onset point of precipitation for different solvents. The results show that the PC-SAFT EOS correlates more accurately with the experimental results over a wide composition interval.

In the 1970s، regulations in some countries forced users of heavy residue to limit pollutant emissions at industrial sites، also forced producers to upgrade their heavy products for export and domestic use. For this reason Iran as a producer، exporter and consumer has to develop new upgrading processes. The most common processes for upgrading heavy oil are catalytic processes، but existence of heavy metals، asphaltenes، sulfur and nitrogen compounds in heavy oil poses several serious problems in the process. Hence at first، the unwanted materials must be lowered to the acceptable limit in the feed. Of all the techniques conceived and tested to separate asphaltenes from oily feed، only one has been developed industrially، deasphalting by light solvents. In this study، deasphalting of vacuum bottom of Tehran and Arak refineries were evaluated using light alkane solvents such as n-pentane، n-heptane and L. S. R. G. (Light Straight Run Gasoline) and compared with propane deasphalting units in refineries. Results show that pentane and heptane are good solvents for asphaltene separation as well as nickel، vanadium، sulfur and nitrogen compounds but more efficient compared to propane. Finaly، according to the qualitative and quantitative specification of produced DAOs using pentane، heptane and L. S. R. G. it was shown that liquid solvents are suitable feed for catalytic units (e. g. FCC) after unifining process.

Use of passive samplers has major advantages with respect to weight, cost and maintenance. In order to measure ambient concentration of nitrogen dioxide, a diffusion type passive sampler was made and then investigated. The manufactured samplers were exposed to ambient air in parallel with continuous chemiluminescence analyzer during weekly to four-week periods. The results show good repeatability as well as good agreement between passive and instrumental methods. Optimum time of exposure was found to be one week.