چكيده به لاتين
Abstract
Sulfur components such as hydrogen sulfide, mercaptans, and elemental sulfur in sour gas cause operational problems in reservoirs, surface equipment, and natural gas transmission networks. Sulfur deposits in the formation around the well reduce production and in some cases even cause the well to block. At surface, this phenomenon has also been reported in places such as flowmeters and barometers where temperature and pressure change. In order to prevent economic losses, the development of thermodynamic models is necessary to better understand the phenomenon of sulfur deposition. Elemental sulfur deposition modeling plays a very important role in predicting the operating conditions of solid sulfur formation, location and amount of deposit. Therefore, in this dissertation, an attempt has been made to provide a suitable thermodynamic model with high accuracy to predict the solubility of elemental sulfur in sour gas. In the introduced model, two equations of Peng Robinson state and PC-SAFT are used for solid-gas equilibrium calculations. The computational accuracy of these two equations is also compared. To improve the solubility calculations of elemental sulfur, the binary interaction coefficients between sulfur and the three main components of sour gas, namely hydrogen sulfide, carbon dioxide and methane, are optimized in four different modes. The modes defined for the binary interaction parameters are as follows: The first mode optimizes the kij BIP independently of temperature. The second case, the kij BIP, is optimized as a function of temperature. Case 3: The Two kind binary interaction parameters kij and lij are optimized independently of temperature. Fourth mode kij and lij are optimized separately for each temperature. To validate the computational power of the equation of states, first, the modeling results of elemental sulfur solubility in pure hydrogen sulfide, carbon dioxide, and methane are compared with 35, 22, and 16 experimental data, respectively. The average total computational error for pure hydrogen sulfide, carbon dioxide and methane gases with improved Peng-Robinson equation is 0.029, 0.0677 and 0.1613, respectively, and with PC-SAFT equation of state 0.021, 0.0627 0.18, respectively. The results of these two modeling methods are compared with previous results. These equations of states have also been used to calculate the solubility of elemental sulfur in a sour gas mixture.
Another important achievement of this research is the calculation of PC-SAFT state equation parameters for elemental sulfur using experimental data on vapor pressure and pure liquid sulfur density.
