Determination of granule (prill) movement modes in the prilling tower for mineral fertilizer production

Abstract

The object of research is the mode of movement of the granules of mineral fertilizers obtained in the towers. The subject of research is the effect of the physical and chemical properties of granules, their size and initial hydrodynamic parameters on the speed of movement of the granules in the tower. The fertilizer industry is characterized by high requirements for the production of mineral fertilizers, which makes it promising to use granulation plants of large unit capacity, tower production. The resulting product must have a stable physical and chemical composition, be monodisperse with a spherical shape of granules, which allows long-term storage in bulk without the use of auxiliary equipment and meet international quality standards. The main granulation equipment that is used in the tower production of mineral fertilizers is spray type granulation equipment. In such towers, there is a likelihood of crossing pellet flares, getting pellets into the walls of the pelletizing tower and adhesion of the melt on this surface in industrial conditions, which leads to negative consequences. Therefore, the determination of the modes of motion of granules is still important. Methods of mathematical modeling of the movement of granules under different conditions were used in the work. Numerical methods were used to solve the equations of differential equations. As a result, an equation was obtained to determine the speed components along the x and y axes. The calculation of the horizontal speed of the granule and the determination of the time of its movement in the working area of the prilling tower makes it possible to determine the length of the granule path in this direction, to determine the diameter of the spray torch of the granules. Provides information on preventing the ingress of granules into the walls of the prilling tower and adhesion of the melt on this surface in industrial conditions, which leads to negative consequences. The magnitude of the speed, especially for the vertical component, changes its value several times over time due to a change in the mode of motion of the granules when moving from the granulator down the tower. This indicates the need to also take into account the change in the value of the resistance coefficient over time. When deriving the equations, simplifications were used, and the motion of a solid granule was considered. However, a drop begins to move from the granulator (disperser), which then crystallizes into a granule. Comparing the obtained results, allowing to predict by calculation the behavior of the spray plume of granules, with the initial ones obtained in industrial conditions, it is possible to conclude that the error of the equations obtained is 10.5%. Therefore, work on improving the obtained equations describing the mode of motion (speed) of the granules will be continued.