Structure Analysis And Research Of Box Airflow Friction

Friction device is an important part of triboelectrostatic separator. Airflow friction device can allow mineral particles which are driven by the gas phase colliding with friction surface and charging. Researching airflow friction device structure and internal flow rule will benefit to the improvement of particles charge and triboelectrostatic separator’s separation efficiency.This paper focuses on particle friction charge. Computational fluid dynamics software ANSYS.Fluent is used to research the gas-solid phase flow’s properties in airflow box friction device by numerical simulation. This paper discusses the affecting factors of friction charge process, analyzes the two phases flow properties in friction device and ascertains the equation of mineral particles air transportation. Square tube, three tube, fold line tube, clapboard tube and net tube are designed as shapes of friction device. Three-dimensional model of the five devices determining a mathematical model and numerical simulation solving method are built. The researches of changes of structural parameters and operating parameters of the five devices have been done to discuss the change of gas-solid phase flow properties and the optimization of device structure. This paper summarized particles collision friction law in friction charge device, provided technical support to the improvement of friction device and promotion of charge efficiency.Study of influence factors of friction charge indicated that physical and chemical properties of materials such as dielectric constant, size, shape, moisture, temperature, and lattice defects affect the friction charge. Meanwhile, the number of materials contact with the friction surface, particle velocity, contact time and the effective contact area also have an important influence on the particles friction charge.The test includes numerical simulations about five friction charges. For square tube, it should take the square pipe section with a smaller length of side; For three tube, as a base structure of three tube, the fork tube is appropriate. When fork angle increases, the fork tube will hinder gas-solid two phase movement. When it decreases, the tube will weaken the solid phase friction. Larger flow velocity will benefit to particles friction in fork tube; For fold line tube, the structure should contain longer section length, more folds and moderate fold angle; For clapboard tube, plate thickness and spacing will affect the distribution of two phases flow field. Increasing wavelength and amplitude, using peak-to-valley sinusoidal clapboard arrangement will effectively benefit to particles’charge in friction device. For net tube, increasing mesh size and reducing net opening ratio are good at particles friction while two phases flow isn’t disturbed. Meanwhile, increasing net spacing and reducing net incline angle is also beneficial.