• Keeping granulate a clean deal

    The DeDuster technology from Pelletron promises prevention and removal of angel hair and dust in plastic granulate – especially for usage in packaging systems for plastic granulate.


    A mobile DeDuster (left) below a silo and next to it a bagging plant which is placed below another silo.
    A mobile DeDuster (left) below a silo and next to it a bagging plant which is placed below another silo; in the next step the DeDuster can be moved towards the right, above this packaging machine.

    Plastic granulate has to be clean, no dust, no angel hair, to meet today's quality requirements of plastic processors, for the production of high quality finished products . The plastic processor expects a dust-free product without angel hair from the plastic manufacturer. This requirement creates high demand for the plastic production plant. Almost all of today's plants clean the granulate, using some type of counterflow classifier (elutriator) after of pneumatic conveyance. These classifiers are installed either upstream of the storage silos followed by slow granulate conveyance, or directly above the storage silos.

    The traditional cleaning technology and their positioning causes two problems. First, the cleaning with ordinary counterflow classifiers does not meet today's requirements for remaining dust content and angel hair, especially when long angel hair pass through the classifier.

    Remaining dust content increases

    Additionally, the remaining dust and angel hair accumulate on the walls and under the roof of the silo after the classifier. With emptying the silo the dust and angel hair slowly slide down and collect in the silos cone. While emptying, this leads to “dust surges”, that is, material bagged from this portion has a very high content of dust and angel hair.

    In a conventional pipe bow (left) frictional heat damages the granulate. The Pellbow (right) reduces the flow speed in the area of the bend and minimizes attrition & abrasion.

    A Dedusting located after the silo and before the packaging is recommended to solve this problem. This is possible using the DeDuster® technology developed by Pelletron. The remaining dust content after cleaning by the DeDuster is in the range of <50 ppm or <30 ppm, depending on material and measurement method. Both angel hair and bird nests, can be easily removed by the DeDuster. Therefore, high-maintenance drum screens for removal of the angel hair are no longer necessary.

    Mobile usage directly above the bagging plant

    Since the build height of the DeDuster is very low it is possible in most cases to upgrade existing plants. A DeDuster with a throughput performance of 40 t/h comes with an installed height of only approximately 1 m. Pelletron offers stationary as well as mobile solutions for this. For bagging plants Pelletron has developed a specialized mobile device that can be moved above the bagging machine. This kind of mobile DeDuster plant has been retrofitted to many existing plants already.

    Due to its compact design the Pellbow can be easily retrofitted.
    Due to its compact design the Pellbow can be easily retrofitted.

    The DeDuster® does not interfere with the bagging machine’s precise dosing system since it is separated from the bagging machine and does not need motors, which might create disturbances during the weighing process. Pelletron offers different versions of the mobile series, i.e for loading of silos or octabins.

    The dust and angel hair being removed by the DeDuster are collected by a cyclone, while the air required for the cleaning is recycled into the DeDuster after passing an inline filter. This technology is available for throughput performance of up to 150 t/h.

    Angel hair doesn’t have to be formed at all

    Pelletron also offers solutions to reduce the formation of dust and angel hair. Instead of a conventional dilute phase conveyance or a combined plant with dilute phase conveyance and slow motion conveyance Pelletron offers Strandphase transportation in conjunction with Pellbows.

    Strandphase is a highly charged pneumatic conveyance with reduced speeds in the range of 15 to 25 m/s. Instead of normal pipe bends Pelletron uses Pellbows, which reduce the conveyance speed in the area of the bend and therefore minimizes the forming of dust as well as angel hair.

    At product change the Pellbow completely emptied, which according to the manufacturer, requires no additional purging air. Its compact design simplifies installation or retrofitting. Even for abrasive materials like glass fiber filled pellets the Pellbow has proven to be wear-resistant due to its operating principle.

    The solution called Pellcon3 consists of the three components Strandphase, Pellbow and DeDuster and is a proprietary conveying process. Pelletron offers retrofitting of existing plants with this technology as well.

    Source: K-Zeitung


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