Numerical Simulation Of Gas Flow Field And Experimental Investigations On Electrocyclone

The data of the three-dimensional velocity distribution in electrocyclone are tested by using the five-orifice pitot on the basis of arranging corona wires near the vortex finder without additional voltage. Moreover, pressure drop and separation efficiency are tested for electrocyclones under different condition.The modified k — ε model are used to compute the gas turbulent flow in the electrocyclones on the basis of body-fitted coordinate system under the different corona wires' arranging position. The numerical results are in agreement with the tested data.When the corona wires are arranged close to the vortex finder, the tangential velocity fluctuate largely in the place near to corona wires, namely yielding a large decrease. From the whole measuring space, due to the effect of the corona wire, the average tangential velocity decreases, and the diameter of interface of inner-vortex and outer-vortex is increased from normal cyclone's 0.5de to electrocyclone's 1.2de (de is the vortex finder's diameter).Compared with the normal cyclone, the tangential velocity in the downward flow zone for electrocyclone increases by 5%~13%. The tangential velocity in upward flow zone decrease by 20%~45%. In the whole flow zone inside the electrocyclone, the average tangential velocity decreases obviously.Owing to the effect of corona wires, pressure drop coefficient of the electrocyclone with corona wires arranged close to vortex finder decreases by 30% in comparison with normal cyclone without the corona wires. This is the same as the conclusion derived from flow field analysis. At the same time, total separation efficiency increases by 2~3%, because of corona wires arranged close to vortex finder but no voltage, compared with same cyclone without corona wires, namely, the corona wires have effects of increasingseparation efficiency and decreasing pressure drop.When the corona wires are arranged in the center between vortex finder and cylinder, due to the disturbance from the corona wires, in the outer-vortex zone close to cylinder, the tangential velocity decreases a little, but the tangential velocity increases in inner-vortex zone, compared with electrocyclone arranging corona wires close to vortex finder. The outer-vortex zone is effective separation region, in the aspect of centrifugal force separation, it is favorable for tangential velocity to be bigger, however, oppositely the corona wires slower the tangential velocity in outer-vortex zone and thus leads to the decrease of separation effect by centrifugal force. On the other hand, it has benefit for the reduction of pressure drop to arrange corona wires in the center between vortex finder and cylinder. Pressure drop coefficient of electrocyclone is 3.5, it decreases by 48.5% in comparison with normal cyclone without corona wires..Under the condition of corona wires arranged close to vortex finder, models for tangential velocity are given in the zone between the walls of electrocyclone and the outer side of corona wires' frame work.According to the distributions of electric field and gas flow field, the migration velocity of particles in effective separation zone is derived for electrocyclone. The calculation results and tested data show that it has respectively shortage and advantage to arrange corona wires close to vortex finder or in the center between the cylinder and vortex finder.