Investigation of factors affecting fine formation in high density polyethylene production process

Morphological control is one of the important issues in the development of catalysis industries in the polyethylene production process. New generations of catalysts for the production of polyolefins exhibit different behaviors during the fragmentation process. In the initial stages of polymerization, fragmentation occurs with the rapid penetration of ethylene monomer into the pores of catalyst with low mechanical strength, which causes the formation of fine particles. On the other hand, particles formed during the polymerization process may be broken due to collision with each other, the stirrer or the wall of the reactor, and particles smaller than the standard size can be produced. In the case of catalysts with low mechanical strength, the formation of fine particles would occur considerably. These particles with a smaller size than usual (>63 µm) are known as fine powder. The presence of fine powder particles is one of the important problems in the polyolefin industry, especially polyethylene, and causes problems such as the formation of a layer on the reactor wall and hot spots, clogging in the gas phase reactors and peripheral equipment such as heat exchangers, pumps, dryers, and the production of undesirable and non-standard products. Today, in the polyolefin industry, they are always looking for a way to reduce the amount of fine powder particles in the polymerization process. In this article, due to the importance of this issue, substantial factors of the formation of these particles, including process and catalysis factors are discussed.