Study On Natural Gas Condensation Characteristics In Supersonic Separation

Natural gas generally contains saturated with water and heavier hydrocarbons, it is easy to condense as a liquid when in the gathering process, resulting in blockage of equipment pipelines and valve, especially the corrosion will occur in the presence of acidic gas, so the removal of the water and heavy hydrocarbons of the natural gas are a necessary part of the gathering process. Conventional dehydration and hydrocarbon removal of natural gas method commonly have the shortcomings of huge equipment, high investment and operating costs, high renewable energy, environmental pollution et al, at the same time it is difficult to apply in the desert, offshore platforms and other remote and dispersion places, the supersonic cyclone separation technology has broad application prospects due to the advantages of compact structure, unattended, cost savings and environmentally friendly.In this paper, according to the conditions of feed gas, based on the preliminary laboratory studies, the use of more advanced structure built the three-dimensional physical model of supersonic cyclone separator. By introducing the spontaneous condensation model and turbulence model, in consideration of the gas-liquid phase coupling conditions to establish a numerical model of the condensation process of multi-component mixtures, make the reasonable meshing and algorithm selection, use the CFD numerical simulation technology to research the flow distribution and condensation parameters (such as the degree of subcooling, nucleation rate, supersaturation, etc.) changes in the supersonic nozzle, the results indicate that the condensation process is conducive to the stability of the flow field, the gas molecules begin to gather and condensation occurs when the subcooling and supersaturation reach the maximum. While the temperature and pressure characteristics were analyzed in the supersonic nozzle to obtain the variation of condensation parameters when the inlet temperature and pressure changes, the analysis showed that non-equilibrium condensation process can be facilitated by an appropriate reduce the inlet pressure and increase inlet temperature.According to the condensation laws inside the supersonic nozzle, on the basis of the continuous phase flow field, on the use of the discrete phase model simulated three trajectories of the droplet and distribution of discrete phase parameters within the separator, indicating that most of the droplets can be separated. Simultaneous analysis the separation efficiency affected by the different droplet parameters and the number of diversion leaves, the results show that the separation efficiency is significantly affected by the droplet diameter and number of leaves, with the increase of the droplet diameter and number of leaves, the centrifugal force which the droplet suffered by increased, separation efficiency also increased. The analysis of dry gas dew point which leaving the supersonic separator showed the given supersonic separator structure have excellent dehydration performance, can meet the needs of most of the domestic gas field.