FL, FG series vertical boiling granulating drier principle is the material powder particles, in the raw material container (fluidized bed) was annular flow state, by after purified air is heated by the preheating and mixing, binder is sprayed into the spray solution, the number of particles poly integrated containing bonding agent aggregate, due to the hot air of the material continuous drying, moisture evaporation in the aggregate, adhesive is solidification, the process is repeated, forming ideal and uniform porous spherical particles.