Application of domestic perfluoropolyether grease in extrusion granulator
May 27, 2022
The market research results show that before 2010, the domestic large-scale polyolefin extrusion and granulation units all relied on imports, and the equipment value was relatively high. The lubricating grease products recommended by the three major foreign large-scale mixing equipment manufacturing companies are imported perfluoropolyether high-temperature lubricating greases. The large-scale extrusion granulator technology of Dalian Rubber and Plastic Machinery Co., Ltd. started late and was formed around 2010. At present, the supporting lubrication technology still draws on foreign experience, and imported perfluoropolyether high-temperature grease is recommended. Imported from abroad, the price is high, which increases the maintenance cost of the large polyolefin extrusion granulation unit.
Process flow and main equipment of polyolefin extrusion granulation unit The process flow of polyolefin extrusion granulation unit is: 1. The polyolefin powder, antioxidant, anti-scaling agent, etc. are mechanically sheared, kneaded and kneaded by a twin-screw extruder to plasticize the polyolefin powder into a molten fluid; 2. The molten fluid is transported to the gear pump through the throttle valve and the start-up valve, and after being pressurized by the gear pump, the impurities in the molten material are filtered out through the filter screen on the screen changer; 3. After the fluid that removes impurities in the molten material is extruded in bundles through the die holes of the template, it is pelletized underwater by the pelletizer; 4. The particles are transported to the rotary dryer by cooling water, and the dried particles are sent to the vibrating screen for screening of debris, unqualified granules and qualified finished granules; 5. After screening, the qualified granules are transported to the finished product silo by the fan. The process flow of the polyolefin extrusion granulation unit is shown in Figure 1 below.
The main equipment of the polyolefin extrusion granulation unit is the extrusion granulator, which consists of a drive system, a mixing extrusion system, and an extrusion granulation system. Main components and working conditions of large extrusion granulator Extrusion granulator is a dry granulation process that uses pressure to agglomerate solid materials. The large-scale extrusion granulator is the key equipment in the large-scale ethylene plant. The main components of the extrusion granulator are shown in the figure below. Depending on the type and grade of polyolefin, the temperature of the material in the sleeve of the large extrusion granulator can reach 190 to 300 ℃, or even higher, and the temperature of the parts in contact with the supporting parts material can reach 250 ℃; in the large extrusion granulator The raw materials are in a state of high temperature, high pressure and high shear, and the accessories are under high pressure, and they maintain stable operation and timely response during continuous driving to ensure the pelletizing effect. Performance requirements of large-scale extrusion granulator for lubricating grease The lubrication problem of large extrusion granulator is mainly the long-term high temperature working condition and the large load on the lubricant, so it puts forward the following requirements for the matching grease: 1. Ensure that the equipment is fully lubricated when sliding at working temperature for a long time; 2. At high temperature and high load, the lubricating grease cannot dry up, block the sliding gap, or enter the molten material; 3. It has good compatibility with resin materials, stable performance at high temperature, and oxidation resistance; 4. It has good oil film strength and load-bearing capacity, which can meet the movement needs of the unit during thermal expansion and contraction, and prevent the deformation of the body; 5. It can be well maintained in the lubricated parts without loss. Domestic perfluoropolyether grease takes perfluoropolyether oil as Base Oil, adds perfluororesin material as thickener, and is prepared by special process. Compared with other high temperature resistant mineral oil type greases or ordinary synthetic greases, the evaporation performance and chemical inertness of domestic perfluoropolyether greases, especially at high temperature, are particularly outstanding, and have excellent evaporation performance and extremely high performance. Pressure performance, longer service life under high temperature conditions. The dropping point, sintering load and wear scar diameter of the domestic perfluoropolyether grease products are comparable to those of the imported perfluoropolyether high-temperature grease recommended by the equipment supplier, and the evaporation loss is lower than that of the grease recommended by the equipment supplier. Applications A company's large-scale polyolefin extrusion granulation unit has been in use for nearly 30 years. The temperature of the processed material reaches 180-300 ℃; the lubricated gate part is in direct contact with the material, and the temperature range is 180-260 ℃; the weight of the gate is 900 kg. In July 2015, according to the requirements of the lubrication manual, domestic perfluoropolyether grease was injected into the gate and drive end dust seal of the extrusion granulation unit. During the use period, the production tasks were frequently switched, and the gate movement of the extrusion granulation unit reached 20 times per month, and the dust seal at the drive end also experienced many tests of starting and stopping. During the whole period of use of domestic perfluoropolyether grease, the extrusion granulation unit operates normally, the equipment moves flexibly, and there is no leakage of resin material, and the device drives smoothly without any abnormality. The user confirms that the domestic perfluoropolyether grease fully meets the lubrication requirements of the large extrusion granulator according to the operation of the equipment. The domestic perfluoropolyether type lubricating grease products have stable performance, can meet the lubrication requirements of large extrusion granulators under high temperature and high pressure conditions, and can realize the localization of grease for large extrusion granulators. Using domestic perfluoropolyether grease to replace the grease recommended by the equipment supplier can effectively lubricate and protect the throttle valve, start-up valve, screen changing spool and other components of the large extrusion granulator.
