Experimental Study On Elemental Sulfur Diffusion In High-sulfur Natural Gas

According to elemental sulfur migration pattern found, elemental sulfur is migrating not only in a solid form, but also dissolved in a high-sulfur natural gas diffusion transport.Currently used of theoretical models of the diffusion coefficient has certain limitations, limited to low temperature and pressure;in the high temperature and pressure conditions, it can only be obtained diffusion coefficient by reverse extrapolation in the basis of the theory of diffusion equation; These data have not been more experimental data verification.Therefore; it has very important significance to study the diffusion of elemental sulfur in high-sulfur natural gas under high temperature and pressure.Based on the research on molecular diffusion in the domestic and foreign, this paper carried out the experimental study of the solubility of elemental sulfur of the high-sulfur natural gas at different pressures, temperatures; secondly, on the basis of the solubility experimental of elemental sulfur, carried out the diffusion experimental study of elemental sulfur in high-sulfur natural gas under high temperature and pressure; finally, it has established the diffusion equation which is able to calculate the diffusion coefficient of the elemental sulfur in high-sulfur natural gas at high temperature and pressure.The main results are as following aspects:(1) By establishing a physical dissolution way to measure the solubility of elemental sulfur under different pressures, temperatures,and obtain the solubility data of the elemental sulfur before the experiment of the diffusion, for studying the diffusion experiments of the elemental sulfur to provide the basic data.(2) In the different temperature and pressure conditions,it has tested the elemental sulfur solubility of the four gas (N2?H2S?CO2?CH4).It researched that temperature?pressure? gas composition effect on the diffusion coefficient of elemental sulfur;Studies have shown that solubility of elemental sulfur in the H2S is maximum, followed by CO2, and the smallest is N2.(3) By establishing a test method of the elemental sulfur diffusion coefficient under high temperature and pressure;By measuring concentration changes of elemental sulfur in the two containers under high pressure and temperature, calculating the diffusion experimental data of the elemental sulfur in natural gas under high pressure and temperature.(4) The results show that system temperature> pressure and gas composition have an impact on diffusion coefficient of elemental sulfur. The research show that under the same pressure, elemental sulfur diffusion coefficient increases with increasing temperature; under the same temperature, diffusion coefficient of elemental sulfur decreases with increasing pressure(5) Comparing the experimental data to the calculation data of theory, the result showed that under high pressure, experimental data and the data of the Gilliland's semi-empirical formula?Fuller's Theoretical empirical formula is larger error, its margin of error is 10% to 20%; By amending, the error is less than 2%.Therefore, the equation can calculate the diffusion coefficient of elemental sulfur under high temperature and high pressure, its error is smaller, the result is more accurate.