Pilot Production Line And Process Optimization Of HVDC Cross Linked Polyethylene Cable Insulation Materials

With the rapid development of the economy in China, the powertransmission plays a very important role in the national economy. The insulatingmaterials of high voltage direct current cable (HVDC) have been one of themajor factors restricting its application and development. Despite of the largenumber of long-term efforts by researchers, the breakthrough of a lot of technicaldifficulties, and the solutions to some key issues, there is still a huge gapbetween the overall performances of the insulating materials of HVDC crosslinked polyethylene (XLPE) with the industry expects. Although there are manydomestic manufacturers, few can produce high quality products that can competewith foreign manufacturers. At present, only Borealis Company can achieveindustrialization and large-scale applications of insulting materials of HVDCXLPE by the method of organic chemical modification, and they basicallymonopolized the market and prices. Therefore, the development of highperformance HVDC XLPE insulating material is a very important hot topic.In this dissertation, the preparation method suited to industrial production isstudied and summarized based on the characteristics of high voltage level directcurrent cable. The method of peroxide cross-linking and the addition ofnanometer additive is used to improve the performance of XLPE. Severaldomestic manufacturers of chemical raw materials are compared, and the basematerial, the technological formula and several major additives which are suitedto insulating material production are discovered. The production equipment inthe experiment is completely localized, the twin-screw extruder, the melt pump,the filtration system, and the underwater pelletizing system are analyzed in detail.Besides, some difficult problems of the melt filter and underwater pelletizing are studied and innovated. The weightlessness electronic scale with high sensitivityhas strictly controlled the production capacity.With the summary of the technique in production process, the processcontrolling parameters are standardized. Through the cooperation of the pressure,temperature and screw speed of the device, the maximum yield is obtained. Withthe analysis of the mechanical property, dielectric performance, breakdown fieldstrength, conductivity current, microscopic structure and space chargedistribution, the products are up to the standard. The research in the thesis canprovide some basis to achieve high efficiency, high output, high quality, and lowwaste industrial production.