【Haichuan’s Best Practices】The technical upgrade project for oil mist recovery in the nitrogen-sealed fuel tanks at the Yan’an Oil Refinery has been successfully implemented, effectively solving the problem of oil accumulation that has long plagued production processes

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Recently, the technical renovation project for oil mist recovery in the nitrogen-sealed oil tank at the Yan’an Refinery of Yanchang Petroleum Refining Company was successfully completed. This not only significantly reduced the concentration of oil and gas emissions from the lubricating oil tank but also completely resolved the problem of oil accumulation that had long hindered production. 　　The lubricating oil tank of the air compressor unit has long relied on a nitrogen sealing system to maintain a micro-pressure environment. In this system, the oil mist generated by the evaporation of high-temperature lubricating oil in the tank is discharged along with nitrogen, resulting in rapid accumulation of oil stains on the equipment surface and making cleaning difficult. 　　Faced with technical challenges, Yanlian established a task force to address oil mist control issues. The task force analyzed the root causes of the problems based on actual production conditions, and taking into account the more than 80 sets of basic parameter reports obtained from on-site investigations, it ultimately decided to adopt oil mist recovery technology for a systematic transformation. The renovation project adopts a technical approach of \"source collection + efficient purification\"; that is, a sealed collection device is installed on top of the fuel tank, and a negative pressure system is used to draw all the volatile oil mist into specialized recovery equipment. Subsequently, a combination of centrifugal separation and deep filtration processes is employed to ensure that the oil in the mist is fully condensed, before the purified gas is released. The task force also optimized the system’s sealing design, eliminating the leakage points present in the original nitrogen sealing system, and achieved full-process control of oil and gas by collecting them as they are generated and purifying them immediately. 　　After the renovation, the oil and gas emission concentration in the lubricating oil tank was reduced to below 2 milligrams per cubic meter. Oil contamination on the surfaces of surrounding equipment decreased by over 90%, and the cleanliness of the working environment improved significantly, providing strong support for the company’s ongoing efforts to pursue green production.