Separations

Introduction:
The natural gas collected from the gas wells is generally saturated with large volumes of water vapor, which inevitably causes clogging and corrosion in natural gas transportation pipelines, valves, and other auxiliary equipment when water vapor condenses out. It also seriously affects the power supply and quality of the natural gas, and reduces the utilization efficiency of the natural gas. Therefore, it is imperative to effectively remove the free water or saturated water in the natural gas treatment process. Supersonic separator is a new type of gas-liquid separation equipment with the advantages of low energy consumption, safe and efficient operation, and pollution-free to environment, which has attracted the attention in the separation sector.

Methods /Analysis:
In this paper, the basic model of supersonic separation was established using numerical simulation . In the supersonic separation device, the helical guide blade was set in the swirl separation straight tube behind Laval nozzle. The flow region was discretized, and the RNG k-ε turbulence model was selected. The second-order upwind scheme was used to discretize the equations and the appropriate boundary conditions were set. The flow characteristics inside the device were simulated and analyzed. A systematic sensitivity study of the influence of the geometry of the helical guide blade on the separation performance of the device was conducted to optimize the blade shape design.

Results/Conclusions:
The distribution of temperature, velocity, and pressure in supersonic separation device were obtained through the numerical simulation that matches the physical model. The flow regime in the upstream of the guide blade is basically consistent with the theoretical design, achieving the low-temperature and low-pressure supersonic flow field. By adding a front cone to the guide blade, the uniformity of the flow regime in the downstream is improved. The effects of the blade number and the pitch of the helical guide vane on the flow regime have been investigated. The model with single blade has the best separation performance due to the weakest shock wave generated, and the model with a pitch of 200 mm has the most uniform temperature distribution, consequently a better flow field than others. The structure of the supersonic separation device has been optimized to increase gas-liquid separation efficiency in this investigation.