Final Drying of Ammonium Nitrate with Nanoporous Structure in Gravitational Shelf Dryers: Hydrodynamic and Thermodynamic Conditions

Abstract

The chapter is devoted to the study of the ammonium nitrate granules structure with nanostructured porous layers, which are obtained as a result of moistening and multistage drying. The necessity of an additional stage of granule dehydration in the technology of porous ammonium nitrate producing has substantiated. Basic constructions of the updated shelf dryers are given. The author’s software for calculating the hydrodynamic indices of the shelf dryer is presented. The regularities of changes in temperature and humidity parameters of the gravitational shelf dryer operation under different hydrodynamic modes are shown. The results of studies regarding the structure of porous ammonium nitrate samples, which was obtained in dryers of different structures under different hydrodynamic and thermodynamic modes, are demonstrated. The results of studies of the nanoporous structure of granules of porous ammonium nitrate after the stage of multistage drying showed the following patterns: an extensive network of deep curvilinear (winding) mesopores of a “modification” character is created; pores are evenly distributed over the entire surface of the granules; smaller pores practically do not merge into ensembles; the number of “mechanical” pores and destruction of the granules is significantly reduced.