چكيده به لاتين
Abstract:
Natural gas is an odorless and colorless flammable gas. Natural gas odorization means operations involving addition of an odorant to gas to ensure characteristic odor of natural gas in order for people the odor to be distinctive and unpleasant so that the presence of gas in air in concentrations below the lower explosive limit is readily detectable. Spotleak 1007(80% tert-Butyl mercaptan and 20% Ethyl methyl sulfide) used as odorant for Iran natural gas. Becouse of very annoying smell of odorant empty barrel and noxious effects of these substances on the environment and human health, deodorizing empty barrel is the issue of national gas company after discharging barrels containing odorous substances. Human health and the environment at risk because of current methods of odor removal by oxidation with sodium hypochlorite so in this study oxidation with ozone, which in terms of speed in operations and environmental issues is an excellent option was proposed. Studies on the reaction of mercaptan with ozone showed that all mercaptans react with a similar rate. The experimental determined rate constants Spotleak 1007 with ozone is 0.797×10-23 cm3.molecule-1.s-1. In this study, due to limitations of the experimental method, CFD method is used to verify deodorising process performance and the effect of various parameters on it. To evaluate the accuracy of the calculations, the time required for deodorizing were used as the criteria and the results of the simulation showed the error of 9.34%. 2D and 3D simulations show that the dead zone is formed inside the reactor and the volume of these areas increases by increasing the gas flow entering the reactor. Also with increasing the amount of odorant in the reactor deodorizing time is increased. With increasing flow rate of inlet gas due to reduced ozone residence time in the reactor, the mass fraction of Spotleak 1007 increases in the output. According to the simulation results, as the temperature increases, the output mass fraction of Spotleak 1007 increases and also as the pressure and concentration of ozone in the inlet gas increases, the output mass fraction of Spotleak 1007 decreases. The helical coil provides sufficient residence time for the reaction of ozone with Spotleak 1007 in outlet stream of the reactor.
Keywords: Mercaptan, Ozone, Deodorization, Computational Fluid Dynamics (CFD)
