Research On Structure Optimization Of Pigmentable On-line Separator For Natural Gas Pipeline

There is usually a certain amount of fluid accumulation in low-lying areas of fluctuating natural gas gathering and transportation pipelines,which will cause increased pipeline pressure drop,rise in wellhead back pressure and corrosion,which will seriously affect gas field production and operation.Setting up online gas-liquid separators in low-lying areas is an effective way to remove effusions.However,most of the current online separation equipment for wet gas pipelines have technical barriers such as poor separation effect,large separation pressure drop,and the inability of the separator to piggy through the pig.This article mainly studies the on-line separator of the passable natural gas pipeline,which is of great significance to improve the separation effect,solve the problem of pig passing,and ensure the stability of pipeline transportation.In this paper,theoretical research and literature data analysis are used to put forward the structure of the pigmentable online separator.According to the gas-liquid two-phase apparent flow velocity parameters in the gathering and transportation pipeline,the internal diameter of the separator’s annular chamber,the length of the hole and the length of the branch pipe,etc.By calculation,the size range of each component of the separator was obtained,and the optimal structure and size of the pigmentable online separation equipment under different working conditions were simulated by Fluent,an experimental prototype was manufactured according to the simulation results,and an indoor experimental system was established for indoor testing.In the experiment,the effect of different inlet conditions and slot lengths on the separation effect was investigated,and the influence of the inlet flow pattern of the separator on the pressure drop and efficiency of the separation equipment was observed,and the structure and size of the separator were obtained under different working conditions.The law of influence on the separation effect,and the establishment of design criteria.The main findings are as follows:Through theoretical calculation and simulation analysis,two kinds of single-chamber and dual-chamber natural gas pipelines can pass through the pig on-line separation equipment.The analysis of the simulation results shows that the increase in the inner diameter of the annular chamber can improve the separation efficiency,but the increase in the separation efficiency is not obvious,and the pressure drop also increases;the size of the branch pipe does not have a significant effect on the separation effect,and the inner diameter of the return pipe.The effect of separation efficiency is small,and it is generally appropriate to select the diameter of the return pipe to be smaller than the diameter of the branch pipe by about 5 mm.The gas inlet flow rate of single and dual-chamber separators has a greater impact on the pressure drop.As the gas flow rate increases,the pressure drop increases exponentially.The pressure drop of dualchamber separators is generally nearly double that of single-chamber separators;the separation efficiency of dual-chamber separators Better than single-chamber separators,single-chamber and dual-chamber separators have a process of first decreasing and then increasing with the increase of gas velocity at high liquid velocity.Through experimental testing of the separation effect of single-chamber and dual-chamber separators under different inlet conditions,the following laws have been obtained:(1)From the perspective of overall separation efficiency,when the separator inlet is a stratified flow pattern,The single-chamber and dual-chamber separators can completely separate the liquid phase.When the inlet flow pattern of the separator is a slug flow pattern,the separation effect of the two kinds of separators is the worst,and the separation efficiency of the dual-chamber separator is generally higher than that of the single-chamber separator.The separation efficiency of the single-chamber and dual-chamber separators rises and falls in a “V” line with the increase of the apparent gas velocity;(2)From the separation pressure drop of the separator,when the apparent flow velocity of the inlet gas-liquid two-phase is small,the single-chamber,The pressure drop of the dual-chamber separator is small and approximately the same,both at about2 KPa.With the increase of the apparent flow rate of the gas and liquid phase,the separation pressure drop increases,and the separation pressure drop of the dual-chamber separator is significantly higher than that of the single-chamber separator;(3)In terms of the size of the separator,the longer the slot length,the higher the separation efficiency,but the maximum length of the slot is limited by the length of the pig.Finally,the PID control system is used to control the liquid level in the bottom liquid collecting shell to ensure that the liquid in the shell is discharged in time;the state of the pig in the separator is simulated,to prove the feasibility of the separator to pass the pig.