Effect of dry / wet steam outlet area ratio on the performance of supersonic separator

This study utilizes the volume of fluid method and dynamic contact angle model to numerically investigate the wetted area dynamics during droplet impact on square, cylindrical, and triangular pillar arrays. User-defined functions are implemented to real-time monitor wetted areas on the array substrate, pillar side surfaces, and pillar top surfaces with dimensionless parameters like the wetted area ratio (maximum to steady-state wetted area ratio) defined for analysis. The influences of Weber number (We) and static wall contact angle (θ) on wetted area are systematically examined. The results show that in triangular pillar arrays, the pinning effect restricts droplet spreading and retraction, yielding the smallest wetted area ratio. However, the side surface wetted area and steady-state total wetted area are the largest among the arrays studied. In square pillar arrays, the groove-driven effect dominates to produce the largest wetted area. Cylindrical pillar arrays, with smooth surface curvature facilitating flow division, exhibit the optimal bottom surface wetting and relatively rapid droplet retraction. Although the top surface wetted area is minimal, a pinning–depinning–repinning cycle occurs at low θ. The side surface wetted area constitutes the primary component of the total wetted area, accounting for the highest proportion. Micropillar geometry predominantly dictates the fractional distribution of wetted areas, with We and θ exerting weak influence. These findings furnish both quantitative foundations and engineering insights for designing hydrophilic microstructure surfaces.

Evaluation of dynamic behaviors in varied swirling flows for high-pressure offshore natural gas supersonic dehydration

Carbon capture, utilisation and storage (CCUS) is of unique significance for building a green and resilient energy system, and it is also a key solution to tackle the climate challenge. The concept of supersonic decarburization, a joint product of non-equilibrium condensation and swirling separation, can contribute to CCUS technology in a clean way. In this paper, a numerical model is established and validated to investigate the complex physical phenomena of supersonic decarbonization in a high-pressure environment based on the real gas equation of state. The model is compatible with the pure CO2 model and CH4-CO2 model. Through the simulation of the supersonic nozzle and supersonic separator, the condensation and separation performance of supersonic decarbonization technology was evaluated. For the condensation performance of carbon dioxide, the results show that higher pressure makes it much easier to achieve the condensation process. When the pressure is supercritical, the decrease of inlet temperature or the increase of inlet mole fraction of CO2 leads to a higher liquid fraction. For separation performance, when the mass concentration of inlet heterogeneous droplets increases from 0.1 kg/m3 to 7.5 kg/m3, the carbon separation amount increases from 3.33 ton/h to 4.43 ton/h, while the exergy loss of condensed CO2 drops from 436.57 kJ/kg to 329.56 kJ/kg. It demonstrates that the decarburization process is easier, and exergy required for condensation decreases when the concentration of the foreign core is larger. This new concept is beneficial to CCUS technology and can be applied to carbon capture in offshore natural gas processing.

Supersonic separator’s dehumidification performance with specific structure: Experimental and numerical investigation

Experimental investigation and numerical analysis of separation performance for supersonic separator with novel drainage structure and reflux channel

A study on the flow and separation performance of supersonic gas separator is carried out through numerical simulation and experimentation. The effect of area ratio on the separation performance under low pressure ratio has been researched. The simulation results indicate that with an increase of the area ratio AR, the intensity of the shockwave increases and the location approaches the throat; Shockwaves are absent in the diverging section of the nozzle when area ratio is 1.063 and the pressure ratio is within 1.25-1.75, which reaches the highest separation performance. The calculated and experimental results also show that the separation performance is the highest and can reach 40.82% when pressure ratio is 1.75. The calculated values are in agreement with the experimental results.

The impacts of structural parameters on performance and energy loss of the supersonic separator: A sensitivity analysis

Improvement of recovery of gaseous fluids using the replacement of supersonic separator instead of Joule–Thomson valve in dehydration/NGL recovery unit with computational fluid dynamic modeling

Structure improvements and performance study of Supersonic Separation device with reflux channel

Performance of Dual-throat Supersonic Separation Device with Porous Wall Structure

Supersonic separation is a novel technology. A multi-fluid slip model for swirling flow with homogenous/heterogenous condensation and evaporation processes in the supersonic separator was built to estimate the separation efficiency. This model solves the governing equations of compressible turbulent gas phase and dispersed homogenous/heterogenous liquid phase considering droplet coalescence and interphase force. Its prediction accuracy for condensation and swirling flows was validated. Then, the flow field, slip velocity and droplet trajectory inside the separators with different swirl strengths were investigated. The maximum values of radial slip velocity are 29.2 and 8.26 m/s for inlet foreign droplet radius of 1.0 and 0.4 µm. It means the larger foreign droplet has a better condensation rate. However, the residence time of larger foreign droplet in core flow is shorten. Thus, the inlet radius of foreign droplet has to be moderate for best separation efficiency. Finally, the dehydration performances of separator were evaluated. The optimal radius of inlet foreign droplet to maximize the dehumidification and efficiency was found. For the separator with swirl strength of 22%, the optimal radius is 0.85 µm at inlet pressure of 250 kPa, where the maximum dew point depression is 42.41 °C and the water removal rate is 87.82%.

Optimisation study of a supersonic separator considering nonequilibrium condensation behaviour

Numerical simulation of supersonic separator with axial or tangential outlet in reflow channel

The supersonic separation is a new approach to dehydrate the natural gas in recent years. In the conventional structure, the straight tube is typically combined with a cyclone to create a strong vortex flow. The shock wave usually occurs near the swirling device in the supersonic separator, which can make the flow unstable and decrease the separation efficiency. Due to removing the negative effects of the shockwave, a new-type helical guide blade is designed as the swirling device, installed in the separate straight tube in the supersonic cyclone separator. The flow characteristics in the supersonic separator was investigated and the geometry structure was optimized by performing the computational fluid dynamics modeling methods. The optimization results showed that the model with a converging tube of 190 mm length, a diverging tube of half-cone angle of 5° and a single blade installed in the middle position, is the best supersonic separator model in the dehydration process, which can create the most stable flow field and achieve the optimum separation. In addition, when the outlet back pressure in the diffuser tube is 1 Mpa~1.5 Mpa, the separation performance will be better.

Structure improvements and numerical simulation of supersonic separators