Experiment And Analysis Of Particle Separating Performance On The Outlet Swirl Flow Of Cyclone

The laws and regulations of environmental protection and discharge standard are becoming more strictly in china, for the particle pollution is one of the relatively outstanding environmental problems in recent years. As one of the capital equipment in many occasions, cyclone separator is necessary to raise further overall separation abilities. In this research, experiment and analysis were applied in the double inlet cyclone to improve the overall performance.The document materials were first studied on the application of cyclone separator and swirl flow in recent years, which drew a conclusion that it is still necessary to investigate the influence of the outlet swirl flow on the overall performance of cyclone. Basing on the outlet swirl flow of the high-performance cyclone, the flow field, which result from different inlet velocity, and the separation ability, which is the performance of this flow field on different size particle, were investigated in the way combined with experiment method, numerical simulation and theory analysis.Firstly, the experiment set-up was put up to test the swirl flow field with the corresponding measurement apparatus, which had been calibrated in advance. In this experiment, the swirl flow was tested in the outlet of cyclone by the assembled apparatus of five-hole tube and digital pressure micrometer, with which set-up based on the XSTM-II cyclone in the experiment.The analysis of data in the experiment displays the flow field profile that can be used to analyse the separation ability of this field. The result of analysis discloses the swirl flow field is a kind of quasi-forced vortex flow, which is a kind of efflux of the swirl flow in limited boundary. The tangential velocity profile can be expressed by the equation Ut*=kr*0.5, in which the k value can be received by regression method. The outlet swirl flow is neither the unanimous in axial velocity direction nor the phenomenon less in backset currents. In the meanwhile, the more violent decay come forth in trie area near the wall. In addition the radial velocity is the smallest of the three components and is directed outward almost everywhere, whose influence on the separating performance can be neglected for its low order of magnitude. In general, the flow field distribution can be regarded as the counterpart of numerical simulation and the basis of the theory analysis.Through the conservation principle of moment of momentum, the transform model, which use similarity method, was set up, which can meet the application in building the relationship among different vortex flow distribution, based on the data of the experiment. According to the analysis of the moment of momentum, the moment of momentum of the same position decays coefficient does not change with different inlet velocity of cyclone.Deriving through the theory and combining with experience formula, the particle density model concerning the outlet of cyclone has been set up. Assetting the definite cyclone general efficiency, the model can be used to calculate the particle distribution in the outlet section of definite particle size, while the model can also get the cyclone efficiency of a single size or in a range of particle size. Result of calculation can offer the effective parameter for swirl flow simulation and separate model following.Combining with the data of the analysis concerning experiment, theory and equations, which can be used to predict the movement orbit of the particle in the vortex flow field, were set up with regard to separating ability in swirl flow. Using this model to analyse the particle movement, the formulas were derived about the time, when particle cracks on the wall, and about the axial distance of particle movement during the time. Applying these formulas, the data was calculated on the axial movement distance and the movement orbit in different particle size, which can offer the outlet pipeline distance in design, aiming at using the separation ability of the swirl flow and giving the effective counterpart of the num...