With the rapid development of polyethylene terephthalate (PET) esterification synthesis technology in recent years, its melt filter cleaning technology has gradually developed from the traditional Triethylene glycol (TEG) alcoholysis method to the hydrolysis method. Polyester melt can not only undergo alcoholysis reaction with TEG, but also undergo hydrolysis reaction with water. The hydrolysis reaction of polyester in the molten state when encountering water or steam is the basic principle of the hydrolysis method for cleaning filter cartridges. Under normal circumstances, the moisture absorption of polyester is relatively low, around 0.4%, but at higher temperatures (80 ℃), the moisture absorption range can reach 2-3%. It is generally believed that this is due to the wetting effect caused by water infiltration into the amorphous zone of polyester. Water in the amorphous region can first promote some weak fractures and provide lubrication for sliding chain segments. The glass transition temperature of polyester is 75-80 ℃. At this temperature, the amorphous region of polyester can exhibit great fluidity, and the molecular chains become more easily movable. The hydrolysis result will greatly increase the molecular activity, where water itself acts as a lubricant. The filter candle core is in the hydrolysis washer to hydrolyze polyester under the protection of high temperature, less oxygen and Superheated steam. Due to the small thermal conductivity of polyester, the hydrolysis time is longer. In order to shorten the hydrolysis time, in addition to the internal factors such as PET structure, such as crosslinking degree, crystallinity and material layer thickness, external factors such as cleaning temperature, Superheated steam volume and steam flow rate should be considered one by one. Using hydrolysis instead of TEG cooking in TEG cleaning can save a large amount of TEG and achieve good cleaning results. This method is increasingly valued and adopted by people.



The steam cleaning system is a new type of filter cleaning device independently developed and put into operation by our company.