Sharif Digital Repository

In this project, ammonia dispersion in the environment have been investigated and the experimental data have been used in order to show accuracy of calculations. Also, the results of CFD have been compared with the results of PHAST software. The results show that when there is no obstacle in the way of gas release, dispersion models will get good results, but due to existence of the obstacle, their error will be increased to 300%. However, the error resulting from CFD is less than 24% even if there are obstacle there. The effects of obstacle’s distance and height on the dispersion of ammonia gas are investigated. This study showed that the concentration of ammonia increase, when the distance... 

In this study, for removing ammonia from air, biofilters which is suitable method for removing odors, volatile organic compounds and toxic materials are used. Biofiltration is an efficient, easy and cost effective, environmental friendly process for degradation of ammonia from waste air. Aim of this study is comparative study of biofilters application for ammonia elimination from industrial sites.In order to remove ammonia, two columns with 14 cm inner diameter were used. One of the columns is filled with vermicompost and mineral shell (mineral shell : vermicompost, 1 : 4) and another column is filled with concentrated sludge and scallop (scallop : concentrated sludge, 2 : 3). Each of the... 

In recent decades, various studies have performed on leaching of sulphide ores in ammoniacal thiosulphate solution for the recovery of precious metals such as gold and silver and significant results have been gained. In this study, the ammonia thiosulfate solution utilized to dissolve copper sulfide concentrate, which contained chalcopyrite. The effect of various parameters such as grain size, thiosulfate and ammonia concentration, solid to liquid ratio, temperature and pH in turbulent leaching process were considered to obtain the optimum conditions in the laboratory scale. The outcomes obtained by chemical analysis were evaluated. The results demonstrate that maximum dissolution (26.72%)... 

Liquid ammonia atmospheric tank (20000 ton) attached to Pardis Petrochemical Complex was ruptured on 8th August 2011 due to overpressure blast injury so that ammonia gas was spread throughout the complex. The current study was aimed to evaluate ammonia leakage and emission from the tank. For this purpose, in addition to evaluate ammonia emission into the air, pressure changes were investigated to simulate the rupture. First of all, ammonia tanks and urea stocks were simulated and then considering two aerial classes (D and B), the incident was stimulated. According to this model, up to 1000 m, was contaminated with 1000 ppm of ammonia. Since there was no experimental data for validating the... 

The release of toxic materials causes tragic accidents every year. There are various techniques in order to mitigate the release effect of these materials such as Application of air jets, steam curtains and water curtains. This study presents numerical calculations to reproduce the continuous ammonia release dispersion with and without the mitigating influence of a downwind water curtain using computational fluid dynamic (CFD) software ANSYS Fluent 15.0. The RNG model coupled with Lagrangian discrete phase model (DPM) was used to simulate the dilution effectiveness of the water curtain system. The ammonia absorption was taken into account by means of user-defined functions (UDF). The... 

Ammonia (NH3) is the second most synthesized chemical in the world which is used about 80% for the production of chemical fertilizers. Industrial production of ammonia commonly relies on Haber-Bosch method that is produced from gaseous N2 and H2, at very high pressure (200-400 atm) and high temperature (400-600oC) on the surface of an iron-based catalyst. But due to required high pressure and temperature researchers are looking for alternative methods that are environmentally friendly. In this research, we applied electrochemical nitrogen reduction reaction (NRR) used nickel oxide (NiO) deposited on nickel foam substrate by hydrothermal method. The prepared samples were treated by nitrogen...