| The combined system of circulation pre stripper & vortex quick separator(CVQS),which was invented by China University of Petroleum(Beijing),is a sort of advanced riser termination system.It combines the advantages of vortex quick separation and dense phase circulation pre – stripper.The device has a higher separation efficiency,can quickly separate out oil and gas,can achieve high effective catalyst prestripping in short time,can greatly save the settlement of internal space,reduce coking.So the residence time of the products in the reactor vessel is shortened greatly.The gas flow field in the CVQS is measured under different operating conditions by an intelligent five-hole probe.It is shown that,the internal flow field of the quick separator system has the following characteristics:(a)Tangential velocity is composed of inner and outer swirl zones,and the tangential velocity is dominant in the process of centrifugal separation.(b)The axial velocity can be divided into upward and downward flow regions,and the boundary points of the upward and the downward flow zones are located near the radial position of the separating cylinder.(c)The radial velocity is small,and it is composed of two parts of the centrifugal flow and the radial flow.The gas flow field data of oil and gas extraction section are obtained by means of experiments.Analysis of the experimental results of the flow field in the oil and gas extraction section,it is found that the gas phase flow field distribution in the lead out section is more disordered,and there is a vortex distribution.This explains why the pressure drop sharply in pressure drop during the test,which can provide guidance for further optimization of the extraction section structure of the quick separation system.At the same time,this paper also studies the effects of jet velocity,internal and external ring gas velocity,bottom stripping gas velocity and inlet concentration on the efficiency and quick pressure drop.According to the experimental results,the empirical formula of the quick separation efficiency is fitted,and the empirical formula for predicting the pressure drop is proposed under full consideration of the quick separator structure size.The experience gained from the calculation values are in good agreement with the experimental results,which can provide reference for engineering design.Finally,based on the internal gas phase flow field and the efficiency of the fast subsystem,a triple region model for predicting the particle size efficiency of the new type of cyclone is proposed.The calculated results show that this model is in good agreement with experimental data within the larger particle size distribution(beyond20 ?m),the maximum relative deviation is under 6.1%;And for the particle under 20?m,there is an obvious difference between experimental value and model value,whose relative deviation is within 45.7% and 80.5%,and with the decrease of particle size,the relative deviation is gradually increased.Therefore,the triple region model has important reference value in CVQS engineering design for separating particles beyond 20 ?m. |
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