Binary Gas Condensation Characteristics In Supersonic Flows

Supersonic hydrocyclone separation is a new technology which is developed on the basis of traditional natural gas processing technology.Compared with the traditional separation technologies,it has the advantage of simple and convenient airtight device and operation method,system without leakage,investment,low operating cost.So it is widely used in natural gas processing field.The supersonic swirling separator is the core of this technology,and laval nozzle is an important part of the supersonic swirling separator.When condensed gas flows through the Laval nozzle due to low temperature effects occur will achieve gas-liquid separation.Natural gas produced wellhead in is a mixture of a variety of components.In order to ensure the good separation effect,we need to analyze the condensation flow of multicomponent gas in the Laval nozzle,and do the research of various kinds of influence factors on mixed gas condensate flow.In this paper,I aim at methane and ethane mixed gas which are the most two kinds of hydrocarbon gas in natural gas and combining the theory of gas dynamics and numerical heat transfer,I explores the flow pattern of double condensable gas condensation in the Laval nozzle.Based on the classical theory of coagulation,I consider the influence of the real gas effects and correct the classical nucleation model as well as establish a suitable gas supersonic condensing nucleation model for double condensable gas.Through the program,I calculate the condensation of nucleation model and comparing the calculated results with experimental data,the reliability is verified.Through analysis,I choose the Gyarmathy droplet growth model.On the basis of previous studies,this paper establish a suitable physical model and verify its reliability.Using ANSYS FLUENT software and by writing and setting the user custom function UDF and user-defined scalar UDS,I simulate the supersonic flow condensation process of double condensable gas and analyz the distribution regularity of the coagulation parameters in the nozzle.Finally,the paper studies the inlet pressure,temperature,double condensable gas component composition and export back pressure influence law of coagulation parameters.The results show that with the decrease of inlet temperature and the increase of inlet pressure,double condensable gas advance the position of nucleation,the maximum rate increases,the droplet number increases,the droplet radius increases,droplet growth rate increase and the export humidity increase.Along with the increase of the ethane content components,the double condensable gas advance the position of nucleation,the maximum rate increases,the droplet number increases,the droplet radius increases,the droplet growth rate increase,the export humidity increase.With the increase of export back pressure,it will cause the nozzle generate the phenomenon of shock wave and make the pressure and temperature inside the nozzle mutate so as to will break the environment of droplet nucleation and growth which is not conducive to mixed gas condensate liquid.