Simulation Study On The Ejection Supercharging Of Natural Gas Containing Sulfur And Wet In Ejector

In view of the continuous decreasing of the welhead pressure in high-sulfur gas fields,this paper proposes a scheme of using the surplus pressure of high pressure gas wells to boost the pressure of low pressure natural gas through ejectors.The natural gas ejector has simple structure,high efficiency and energy saving,but the internal flow law is very complicated,and there are complex physical phenomena such as shock wave,choking,and gas hydrate formation.In the existing practical applications,the ejector is often designed according to the empirical value method,and the complex flow law inside the natural gas ejector is difficult to be observed by field application or experiment.In this paper,the internal flow field of natural gas injector is analyzed by numerical simulation,and the method of improving the performance of natural gas injector is explored.The natural gas ejector is designed based on the improved thermodynamic method.Meanwhile,and the thermodynamic process and irreversible loss in the design process of natural gas ejector are briefly intouduced.A test bench for the variable working condition of the air ejector is built,and the experiment of the variable working condition of the air ejector was carried out.The numerical model of natural gas ejector is established,and the shock wave phenomena in natural gas ejector is simulated and analyzed.The influence of working parameters on shock wave distribution and performance in natural gas ejector is studied.It is found that there is a critical value for the mixing pressure and an optimal value for the primary pressure.The performance of the ejector is gradually improved by the increase of entrained pressure.The double shock phenomenon in ejector is beneficial to stable operation,while the single shock phenomenon is not conducive to the improvement of entrainment ratio.The structure of natural gas ejector is optimized by numerical simulation.The results show that for given operation conditions,the optimum diameter ratio of the equal section of mixing chamber to the main nozzle throat is 1.94,the optimum length range of the equal section of mixing chamber is 8.6-10 times of the diameter of the main nozzle throat,and the optimum tangent value of the mixing chamber convergent angle of the gradual section of mixing chamber is 0.073-0.093,the length of the diffuser chamber has little effect on the working performance of the ejector,when the length is 7.1?17.1 times of the diameter of the main nozzle throat,the ejector can maintain good working performance.The gas hydrate prediction model Zahedi? is used to predict and analyze the gas hydrate formation area inside the natural gas ejector.The results show that when the fluid entering the ejector is single-phase,the range of gas hydrate formation region decreases with the increase of temperature,at the same temperature,the higher the content of hydrogen sulfide,the larger the area of gas hydrate formation.When the working fluid entering the ejector contains water droplets,the gas hydrate formation area is obviously less than that of the single-phase working fluid at the same temperature.Increasing the inlet temperature of the working fluid can effectively reduce the gas hydrate formation in the ejector.