Experimental Investigations Of A Dynamic Cyclone On Gas-Solid Separation

Cyclones are well known for their simple structure, low installation costs, simple operation and maintenance, stable performance, etc., which have played a pivotal role in power plants, incineration plants, ore smelters, sand plant, cement plant, and powder processing plant. However, because separation in cyclones relies on the inertia of particles, conventional cyclones generally have low efficiency for fine particle separation. Over the past few decades, many researchers have attempted to improve cyclone performance. These efforts can be divided into two methods:one is to optimize the configurations and geometric dimensions of cyclones, and the other is to add additional devices to the cyclones.This article continues the research ideas about adding additional devices. The conventional cyclone is improved by adding rotor blades to the cyclone:this new configuration is known as a dynamic cyclone. The separation efficiency is improved significantly. In Chapter 2, the Gambit code was used for the physical model and grid generation; the Fluent code was used for the numerical simulation with suitable turbulent model, discrete particle model, boundary conditions and multiple references frame model. The performance of the cyclone was numerically investigated in detail in terms of the tangential velocity, separation efficiency and total pressure. The effects of the inlet velocity, rotational speeds and the configuration of the blades on the dynamic cyclone were also analyzed. Simulation results show that in certain conditions the separation efficiency of the dynamic cyclone is much better than the ordinary cyclone separator, but the pressure drop of the apparatus as compared with ordinary cyclone also improve to some extent.In Chapter 3, the numerical model was verified through experimentation. The inlet gas velocities were controlled by the guild vane and were measured using a ZRQF-F30J digital multipurpose wind speed gage; the total pressures of the inlet pipe and outlet pipe were measured using a SYT 2000 digital microtonometer and an AS-T-1 Pitot tube; the duration and amount of the feed were controlled by a solid aerosol generator (SAG 410); the fractional separation efficiencies can be determined using an electrical low pressure impactor (ELPI). Although there is a certain degree of deviation between the simulations and experiments, the trend in the change is represented well by the simulation. We also analyzed some possible reasons of this deviation in the thesis.In Chapter 4, the response surface methodology and desirability function have been performed to optimize the blades geometry of the dynamic cyclone including the length, number and inclination angle of blades, which have significant effects on the dynamic cyclone performance. The commercial software Design-Expert was used to design the Box-Behnken’s matrix. Variance, main effects, Pareto chart and the effect of two independent variables were analyzed. Multi-objectives optimization using the desirability function is to obtain the global optimum separation efficiency and total pressure. The optimization is validated through comparison between the results of optimization and the results of simulation according to the optimal configuration of blades. The deviation is less than 3% which prove the application value of the optimization method.Finally, the conclusions about tangential velocity, separation efficiency, total pressure and multi-objectives optimization were discussed in the thesis. In the meanwhile, we talked about the insufficiencies and prospect of the dynamic cyclone technique.