| The oil and gas separation is an important process in subsea production system.Traditional gravitational separators are heavy,bulky and expensive,which limits their extensive application.As an advanced type of separator,the gas-liquid cylindrical cyclone separator(GLCC)draws people's attention with its compact geometry,low cost and easy operation in the subsea condition.Previous research showed that the geometry of the inlet nozzle had great influence on the performance of GLCC.However,the mechanism is still uncovered.In this paper,the effects of different types of inlet nozzles(one crescent inlet nozzle and three rectangular inlet nozzle)on the performance of GLCC are studied based on the method of similarity analysis.The main conclusions are as follows:(1)The criterion relations that show the separation efficiency and the separation pressure drop are derived,which are E=f(N,Rel)and Eug=f(Re_g,Re_l,Fr_g).Meanwhile,the relative importance of the non-demensional numbers is also discussed.And the selection of crucial characteristic parameters in these similarity numbers is also addressed.(2)The flow patterns in the vertical upward pipe and the inclined pipe are observed and such flow patterns can be explained with the existing classical methods.According to the flow patterns of the upper gas space of GLCC,the droplet entrainment mechanism is better understood.It is also found that the flow patterns in the upper gas space of the GLCC is greatly influenced by the geometries of the inlet nozzles,while the flow patterns of vertical upward pipe and inclined pipe are almost free of the influence.(3)The experiment shows that the operation of GLCC can be divided into two regions,one with no LCO(Liquid Carry Over)and the other with LCO.When no LCO occurs,the separation efficiency is 100% and does not change with N,a similarity number combining the gas and liquid properties.Once the LCO happens,with the increase of N,the efficiency falls rapidly at first,then comes to slowly decrease and finally approaches to a minimum Emin such as No.0 and No.1 nozzles.It was also found that the rectangular nozzle has a better separation performance compared to the crescent nozzle with the same cross-sectional area.The No.2 nozzle has the best performance.A new criterion is put forward to judge the onset of LCO.At last,an efficiency formula is established on the basis of the Rose-response function from statistics.(4)The pressure drop of GLCC with different types of nozzles obeys the same trend.Specifically,the Euler number increases exponentially with the gas Reynolds number,and it rises linearly with the liquid Reynolds number.A formula connecting the Euler number with these two Reynolds numbers and the gas Froude number is derived,which reflects the influence of inlet nozzles on the pressure drop.The predicted results of both formulae with respect to pressure drop and efficiency are very consistent with the experimental data,which is of significance for scale-up and applications of GLCC. |
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