Numerical Simulation Of Gas - Solid Two - Phase Flow In Vertical Screw Conveyor

With the growing development of port economy, port logistics quantity has increased by years. Among the many port conveying machinery, screw ship unloaders have won popularity by its environmental protection, efficient, economy and other characteristics. However, the core technology of production design for ship unloaders has still been held by overseas. Considering the cost, it has also been studied at home, aiming to improve the transmission efficiency of ship unloader. It is worth mentioning that the transport efficiency of vertical screw conveyor plays an important role on the whole transportation process of screw ship unloader.To know conveying theory is the first step in raising efficiency fundamentally. Past design theory was just limited to the properties of the material and the interaction between the material and the screw blades. Nevertheless, the existing gas-solid two phase flow theory points out that the gas has important effects on the motion of particles. The vertical screw conveyor is commonly used to transport powdered material. Now the gas-solid two-phase flow theory is introduced into the transmission mechanism of vertical screw conveyor. Meanwhile the analysis software Fluent is used to simulate conveying process in the conveyor.At first the gas phase flow field in the conveyor is simulated to obtain the distribution of the gas flow velocity and pressure, through application of sliding mesh simulated screw blade rotation. That the axial velocity and tangential velocity is large can help to lift materials. The internal pressure is lower than the atmospheric pressure in the early stages. It contributes to feed material rapidly. In the conveying process, airflow vortex is formed within the conveyor. The negative pressure can accelerate the speed of material.Then for the simulation of gas-particle two-phase flow in the conveyor, the Euler model is selected to study particle size, density, filling rate and screw speed on the influence of the lifting speed and concentration distribution of material. Under the premise of considering the gas, particle size is more important to the transmission efficiency. The particle size is smaller and the material in the gas distribute more uniformly. The interaction between the material and airflow is ignored that the lifting speed of material can be improved. The next is screw speed which makes the material distribution in the gas more uniform and accelerates the speed of material. On the contrary, for the small particle size of materials, with the increase of material filling rate, the lifting speed reduces. Material density has not much influence on the distribution of the material and the lifting speed.Thus, the results provide a certain basis for the structure design and the applicable scope and seriation design of vertical screw conveyor.