Abstract:The method of mechanical stirring to separate egg membrane from eggshell has the advantages of high separating efficiency, bulk processing and no pollution to the environment. Fluent 6.3 was used to explore the effects of different stirring rotational velocities, particle diameter sizes and solid-liquid ratios on the flow field characteristics of the particle suspension state, solid holdup distribution, solid-phase velocity and stirring power consumption. Simulation results showed that the scope of particle accumulation at the bottom would be decreased while the solid-liquid ratio was decreased and the solid-liquid ratio should be reduced properly. Particles accumulation was decreased while stirring rotational velocity was increased, but power consumption would be increased dramatically, in order to ensure most particles suspension and reduce power consumption, the stirring rotational velocity should be set as 300~350r/min in experiment. Enlarging particles diameter size can reduce particle accumulation at bottom, lower particles suspension height, and increase the moving resistance of particles along the axial direction in the flow field, so the particles size of 1.5~2.5mm can be chosen for eggshell separation experiment. Therefore, appropriate conditions were obtained for the experiment of separating membrane from eggshell according to the simulation results. Moreover, quadratic orthogonal rotary combination experiments were carried out with factors of stirring rotational velocity, stirring time, solid-iquid ratio and separating medium temperature. The experimental data was optimized and analyzed by Design-Expert 8.0.6. The regression model between the experiment index and the factors was obtained. Meanwhile, the response surfaces were established between membrane recovery and experiment factors in order to obtain the relationship intuitively. The experiment result showed that the importance of stirring rotational velocity to egg membrane recovery was the most, and then the stirring time, separation medium temperature and solid-liquid ratio. The interaction between stirring time and stirring rotational velocity to separation effect was the most significant. Optimization results showed that the membrane recovery rate reached 88.58% while the stirring time was 18.57min, stirring rotational velocity was 337.68r/min, solid-liquid ratio was 0.07g/mL, and the separation medium temperature was 20℃, and the separation effect of egg membrane from eggshell was perfect. Conclusions of numerical simulation and experiment would improve the membrane recovery and utilization of discarded eggshell, and provide a reference for the solid-liquid two-phase flow and related study.
