UTILIZATION OF SPRAY CRYSTALLIZATION PROCESS IN POLYOLEFINS CATALYST PREPARATION

Spray crystallization technology is utilized to obtain the desired pro perties of the catalyst carrier in the polyolefins catalyst preparatio n process. The morphological properties of the catalyst carrier refer to the morphological properties of the final polymer product, which is known as the replica effect. The paper clarifies the factors affectin g the crystallization of the atomized catalyst carrier melt. The probl em in the spray crystallization of the catalyst carrier melt droplets is the agglomeration. The agglomeration tendency arises when the popul ation densities of the uncrystallized spray droplets is high. The surf aces of the droplets have to crystallize before collision. The populat ion densities and the temperatures of the droplets are affected by the flow and temperature conditions of the cooling gas in the spray chamb er. The crystallization rate depends on the metastable zone of the car rier melt composition and the absorption of the evaporated solvent bac k on particle surface. The agglomeration conditions in the chamber are critical in some cases related to regions in the spray chamber where the population densities of the droplets are relatively high and the d roplets collide with uncrystallized particles.