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Research subject: Mazut is widely used in petrochemical, power, and marine industries. The use of these fuels, in addition to causing widespread air and sea pollution in the country, has also led to severe international penalties, rising costs, and corrosion of equipment. Therefore, the use of mazut fuel with sulfur compounds of up to 0.5% in the world, as a refining mazut fuel at the origin (in refineries) and taking into account all aspects, is more important. There are limited industrial methods for the hydrotreating of mazut (Due to the heavy oil cut and the complexity of sulfur compounds in it), the most common of which is hydrogen desulfurization (HDS).
Research approach: The goal of this research, The simulation and economic evaluation of the hydrotreating plant from Mazut fuel with a capacity of 13.75 million barrels per year. The simulation of this process was performed in Aspen HYSYS petroleum refinery software. In this simulation, the effect of effective operating parameters such as pressure, hydrogen to mazut ratio, and finally catalyst consumption on the removal of sulfur compounds, production of by-products, net production costs, and total investment costs are investigated.
Main Results: The results showed that for the hydrotreating process of this mazut with sulfur compounds 3.5%, total capital investment is 308.9 million US$ and the net production cost of treated mazut fuel is estimated to be 114.5 million US$ per year. Also, economic sensitivity analysis showed that the operating parameter of the hydrogen to mazut ratio had the greatest effect on increasing the total capital investment and net production cost, which should be minimized as much as possible.

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Research subject: Hydrodesulfurization is one of the effective methods to remove sulfur compounds from oil fractions and improve fuel quality. One of the major challenges in this process is to find the proper catalyst support that performs best. In the meantime, modified supports with zeolite have allocated a lot of attention due to their strong acidic sites, specific surface area and high hydrothermal and chemical stability; But the acidity and volume of zeolite mesopores need to be corrected.
Research approach: In this study, first, hierarchical Y zeolite was prepared using post-synthesis (Dealumination) and using ammonium form of zeolite and NH₄F solution (0.75 M) at 90˚C for 3h under reflux conditions. Physicochemical properties of zeolite were investigated by BET, FESEM, FTIR, AAS and XRD analyzes. Modified zeolites were used in the support synthesis of the HDS process catalyst. The sulfidation and performance evaluation of the prepared catalysts were carried out in the fixed-bed microreactor were performed with diesel cutting feed from the Isomax unit of the target refinery.
Main results: The results show that the volume of mesopores, specific surface area and SiO₂/Al₂O₃ ratio in hierarchical zeolites has increased 0.073 cm³ g^-1, 783.36 m² g^-1 and 5.2, respectively (initial values are 0.032 cm³ g^-1, 567.18 m² g^-1 and 4.5). The results of zeolite analysis show the preservation of the structure and crystallinity during the zeolite modification process. The effect of zeolite modification, especially the Si/Al ratio variations, mesopores and specific surface area, was investigated on the activity of NiMo/Zeolite+Al₂O₃ catalysts. Increasing the acidity and improving the physicochemical properties of the modified zeolites has increased the catalyst performance in the process of diesel hydrodesulfurization (Conversion= 90%). Improving the activity of catalysts can be attributed to the positive effect of zeolites on the dispersion of the metallic site, surface area, acidity, optimal size of pores and volume of catalyst mesopores.

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The combustion of fossil fuels containing sulfur results in the release of sulfur dioxide into the atmosphere and environmental pollution. Hence, the researchers focused on the biological desulfurization method. Dibenzothiophene is used as the model molecule to study the ability of the desulfurization of microorganisms. The most suitable sources of carbon, nitrogen and sulfur concentration optimized by response surface method to obtain the highest cell growth and biological desulfurization activity. The performance of iron nanoparticles on the growth and biodesulfurization activity of thermophilic bacterium Bacillus thermoamylovorans strain EAMYO was investigated. Characterization of starch-modified iron nanoparticles was performed by TEM, SEM. The images of TEM and SEM of starch / Iron nanoparticles showed that the Fe₃O₄ and Fe0 nanoparticles were 20 and 30 nm, respectively. The investigating the growth of microorganism in the presence of iron nanoparticles showed that these nanoparticles not only did not have a toxic effect on microorganism growth, but also increased the growth of microorganism in 96 h (OD 660 = 1.864, 1.896 respectively in the presence of nanoparticles Fe₀ and Fe₃O₄), while the highest rate of growth in the absence of nanoparticles in 96 h (OD660 = 1.51). Also, the activity of desulfurization in the presence of starch/Fe₀ nanoparticles and starch/Fe₃O₄ / starch increased by 26.52% and 10.75%, respectively, compared to the cells without the coating of iron nanoparticles.
 

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This work presents the numerical results on reduction of sulfur emission from combustion of heavy oil in a combustion chamber. One of the most practical methods for sulfur emission reduction is flue gas desulfurization (FGD). In this study various FGD absorbers have been studied by means of numerical simulations. The flow is assumed turbulent two-phase flow while gas is the continuous and droplets form the dispersed phase. Heavy oil with considerable sulfur contents has been used as the fuel. The results show that, the Na-based absorbers are more efficient than the calcium-based absorbers. In addition, it is found that the efficiency of Sodium bicarbonate (NaHCO_3) is about 96% while the efficiency of calcium oxide (CaO) is about 74%. The efficiency of the Na-based absorbers is higher than the Ca-based absorbers due to the low density of Na-based absorbers. The low density of Na-based absorbers leads to a better dispersion of the absorber particles. The second reason for higher efficiency Na-based absorber is lower activation energy compared with Ca-based absorber. In addition, the mixing of Na-based absorbers dominates the mixing of the Ca-based absorbers. Thus, the reaction efficiency and kinetics of Na-based absorbers dominate in the same conditions with Ca-based absorbers.