Study On The Resistance Characteristics Of The Cyclone Of The Feeding Height In The Swirling Air Flow

The phenomenon of the large negative pressure and the high exhaust gas temperatureat the C1 outlet of the domestic cement precalcining kiln have generally been found in the cyclone preheater of the production line.The study of the cyclone mainly focused on the numerical simulation of the flow field and particle motion trajectory in the cyclone and the simulation of the single-stage cyclone test with the introduction of the parallel gas flow.In this paper,a small engineering experiment was carried out by using the near-similarity principle make the cyclone cylinder model with organic glass.The influence of different swirl flows on the resistance characteristics of the cyclone is studied by changing the rotation direction of the test system.Cold state and hot state experiments were carried out respectively to investigate the effect of feeding height on the dispersion of raw meal in the heat transfer tubes under different wind velocity and ratio of solid gas.Experimental research conclusion as followed:(1)The resistance loss of the cyclone would be increased with the rotation intensity is increased of the pure air flow into the cyclone.In the two-stage cyclone test system,test system pressure drop of the co-directional arrangement system is lower than it in the reverse arrangement system under the same wind velocity.The effect of pure rotary air on the pressure drop of the cyclone will be weaken due to the entry of dusty air flow.The effect of rotation on the resistance of the cyclone system will be decreased with the increase of ratio of solid gas.When the test solid-gas ratio reached 2.0,the rotation direction showed few effect on the pressure loss of the preheater.According to the measured data of repeated trials,the formula of pressure drop of C1 cyclone is summarized under different rotation of the model system.(2)Increasing the feeding height of the material and wind velocity of the cross section are beneficial to the dispersion of the raw meal powder in the heat transfer tube.The same wind velocity,the increase of the material feeding height will increase the energy of the raw meal,which is more conducive to dispersion when the raw meal is colliding with the rotating air.(3)When the feeding height increased from 1.25 D to 5D(D is the tremie pipe diameter),the pressure drop in the heat transfer tube decreased due to the increasing dispersion degree of raw meal.When the feeding height increased from 5Dto 7.5D,the pressure drop in the heat transfer tube increased due to the increasing “disorder” in gas-solid flow.In the thermal test,the heat transfer effect was improved markedly as the feeding height increased from 1.25 Dto 5D.However,the improvement of heat transfer was not significant with a range of scattering height from 5D to 7.5D.The optimal feeding height is 5D in the test system.(4)In the experimental system,the phenomenon of raw meal collapse was observed when wind velocity of the cross-section in the heat transfer pipe is 7 m/s.As the cross-section wind velocity reached 9 m/s this phenomenon was disappear.