How should the polymer melt screen changer be cleaned?
The polyester industry generally uses an extruder screen changer to filter impurities and agglomerated particles in the melt. When the pressure difference of the screen changer rises to a certain level, it is switched to the standby station for use. When the impurity particles in the melt are stable, the switching cycle of the screen changer is mainly determined by factors such as the initial pressure difference of the filter, the accuracy of the filter material, the dirt holding capacity, the cleaning effect of the filter material and the area of the filter. The purpose of the screen changer cleaning is to keep as little polymer residue as possible on the dirty candle filter element for the next step of TEG cleaning and alkaline cleaning. The self-cleaning of the screen changer is divided into 3 major steps. Hydrolysis, pre-oxidation, oxidation.
Due to the different cleaning methods of the hydraulic screen changer, the corresponding decontamination effects are obviously different. TEG is used to cook and wash, and then high-pressure water gun and ultrasonic cleaning are used. The cleaning effect is not good. In the cleaned filter material, it can be clearly seen When there are impurities such as TiO2 (polyester matting agent) that cannot be removed, due to unclean cleaning, there are more and more impurities in the filter material, the filter material becomes significantly heavier, the initial pressure difference of the filter element is high, and it is scrapped in advance. In order to solve this problem, we tested the discarded filter material for pickling. A certain proportion of acid solution has obvious effect on the decontamination ability of the filter material, which can prolong the service life of the filter element.