Numerical investigation on flow and atomization characteristics of hydrated magnesium nitrate gas-liquid two-fluid nozzle

Abstract

The aim of this study is to reveal the atomization process of Mg(NO3)2·2H2O generated in the nitric acid leaching process of laterite nickel ore through a nozzle into a pilot pyrolysis furnace using CFD method. Based on the Euler-Lagrange method, a mathematical model of the hydrated magnesium nitrate gas-liquid two-fluid atomization nozzle was established, which can describe the gas-liquid flow characteristics. A visualization experimental platform was built for whose reliability has been verified by using graphical analysis technique. The influence law of gas channel inclination angle (hereinafter referred to as inclination angle), channel number and gas inlet pressure on the velocity inside the nozzle, liquid volume fraction and velocity and particle diameter of the atomization field were further explored. The results show that the number of gas channels is the main influencing factor for the average velocity at nozzle outlet and Sauter Mean Diameter (SMD) of atomized particles, while the gas inlet pressure mainly affects the volume fraction of liquid. When the inclination angle increases, the average velocity of nozzle outlet increases, and the Average Mean Diameter (AMD) and SMD of the atomized particles decrease. At the same time, the average volume fraction of hydrated magnesium nitrate first increased and then decreased, with the maximum value to 27.91% when the angle is 30°. Therefore, the high nozzle outlet velocity can play an important role in promoting droplet fragmentation and the volume fraction of hydrated magnesium nitrate for the later pyrolysis, only when the inclination angle is set properly.