Key units of Daqing Petrochemical’s High-Pressure Polyethylene Plant 2 set a new record for long-term operation in China

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April 13 marked the 523rd day of continuous and safe operation for the primary high-pressure compressor and the secondary ultra-high-pressure compressor, which are the core equipment of Unit 2 for high-pressure polyethylene production at Daqing Petrochemical’s Polyolefins Department. This represents a new record for the operating duration of similar units in China. It is understood that the primary and secondary compressors are responsible for generating extremely high reaction pressures for the ethylene polymerization reaction, and their operating conditions are directly related to the stable operation of the entire facility as well as production safety. Previously, due to the constraints of manufacturing processes and technical limitations, conducting inspections every six months was the standard practice to ensure the stable operation of the units. Achieving a operation period of over 500 days this time is a result of Daqing Petrochemical’s implementation of the concept of full-life-cycle equipment management and its efforts to establish a closed-loop management system across the entire process. To achieve this breakthrough, Daqing Petrochemical incorporates the long-term operation of equipment into its evaluation system, fosters a culture of competition and learning, and effectively improves overall management standards. On this basis, the company organized various departments to develop maintenance and repair strategies specific to Type A units, following the principle of \"one strategy per unit,\" as well as strategies tailored to each extrusion and granulation unit, under the approach of \"one strategy per product per unit.\" This enables the development of differentiated maintenance and repair plans for each key piece of equipment, thus putting the concept of predictive maintenance into practice. By 2025, the proportion of key pumps and motors in Area A of the polyolefins division increased from 79% to 83%; unplanned shutdowns and production fluctuations caused by equipment and electromechanical issues were significantly reduced, resulting in a marked improvement in the reliability of plant operation. Faced with the challenges of high operating requirements and difficult maintenance for high-pressure compressors, the technical team in the Polyolefins department adopted a strategy tailored to the oil used. They systematically reviewed the usage records of four different types of plunger lubricants over the past 20 years, analyzed in depth their impact on system cleanliness and lubrication performance, and developed targeted technical solutions. To address the issue of insufficient reliability in the existing temperature monitoring system for the connecting rod bearings of the secondary compressor, the technical team successfully upgraded it to a contactless radar signal transmission system, enabling real-time monitoring and early warning of bearing temperatures and thereby significantly enhancing the safety of the unit’s operation. To effectively address the failure risks associated with the long-term operation of the equipment, the Mobile Equipment Department took the lead in conducting a total of 5 assessments on the operating conditions of both the primary and secondary units of the High-Voltage Unit 2. Special maintenance plans were developed, and joint special maintenance efforts involving mechanical, electrical, instrumentation, and control aspects were carried out to conduct a comprehensive inspection of the unit from multiple professional perspectives. At the same time, criteria for shutting down the unit were established to ensure that its operation remained under control. During the recently completed window maintenance, Daqing Petrochemical replaced the heat exchanger’s E5 tube bank with domestically produced units, laying the foundation for a new phase of stable operation of the unit. Next, the company will continue to focus on equipment operation and maintenance as well as technological innovation, striving toward achieving longer operational cycles.