Discussion on issues with polyolefin pelletizers
Thread Content
The polyethylene granulation system is L-shaped, with corners, and it includes gear pumps as well as screen changers. The polypropylene granulation system, on the other hand, is in a straight line layout; it has no gear pumps nor screen changers. In my understanding, such differences in equipment are due to the properties of the materials themselves, specifically their different viscosities, which lead to significant differences in the design of the equipment. Does anyone understand the equipment related to these two aspects? Does anyone know the properties of these two materials? Please analyze them both from the perspective of the equipment and the materials themselves
For polyethylene and polypropylene, the newly installed equipment is equipped with gear pumps and screen changers; I’m not familiar with the L and straight-type models
The comments made upstairs are surprising; it seems they have not inspected the polypropylene granulation system in person. Polyethylene has a gear pump and a screen changer; the L-shaped arrangement means that after the material exits the mixing section, it turns 90 degrees and then passes through the gear pump, followed by the screen changer and finally the granulation system. Polypropylene does not have a gear pump or a screen changer – the components are arranged in a straight line, with only a twin-screw mixing section preceding the granulation system.
Not all polyethylene is of the L-type; the German WP version is of the straight type, while the L-type is produced by Kobe Steel in Japan. Currently, the L-shaped design is widely used in China because it is compact and occupies less space. It is actually related to the properties of the material, mainly its melt index and density. Besides, in polyethylene plants with linear granulation units, some do not even have gear pumps. For example, the WP model 280 high-density product. I don’t know much about polypropylene.