【Haichuan: Lessons from Others】Stable operation yields benefits! Lanzhou Petrochemical’s atmospheric and vacuum distillation units have achieved a record of 1,427 consecutive days of operation

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As of April 23, the two atmospheric and vacuum distillation units, which are the key facilities in Lanzhou Petrochemical’s refining system with capacities of 5 million tons per year and 5.5 million tons per year respectively, have been in operation for 1,427 consecutive days. They have processed a total of 2.96 million tons of crude oil, setting a new record for the number of days of continuous operation. 　　Since the major overhaul of the refining system in 2019, Lanzhou Petrochemical has adhered to the principle that \"stability leads to greater efficiency.\" By taking into account the composition of crude oil, it has arranged the operation of the two atmospheric and vacuum distillation units in a rational manner, strictly controlled process parameters, emphasized regular inspections at various stations, and made every effort to overcome the challenges associated with long-term operation of these units, thereby ensuring their stable operation and boosting production and efficiency. 　　To address the problem caused by the blockage of the atmospheric air-cooling tube bundles in the 5.5 million tons per year atmospheric distillation unit, which led to high pressures in the atmospheric tower and disrupted production, Lanzhou Petrochemical sought innovative solutions and tried bold approaches. By isolating each unit one by one and using custom-made tools, they carried out high-pressure water cleaning of each blocked air-cooling tube, with significant results. This not only reduced the risks associated with these operations but also saved a large amount of money that would have been spent on replacements. 　　Focusing on corrosion prevention through process control, the company has managed low-temperature corrosion in the top condensers and pipelines by improving the qualification rate of electrodialysis, reducing chloride levels, and raising the temperature at the top of the towers. By making use of online thickness measurement and data on changes in corrosion rates detected by probes, it adjusts operating conditions in a timely manner, as well as the amount of corrosion inhibitors and neutralizers used. As a result, the corrosion rates measured online for the two atmospheric and vacuum distillation units have decreased significantly compared to the same period last year, with the annual compliance rate for these corrosion rates remaining above 92%. At the same time, the plant’s staff carried out pulse eddy current inspections on 365 pipe fittings in key areas; 62 cases of corrosion-induced thinning of moderate severity or more were identified. Reinforcement was applied to 42 areas with high risk of thinning, while 19 areas with severe corrosion were placed under close monitoring. 　　In addition, the company strictly adheres to the regulations regarding \"dual-duty aircraft\" management. It holds regular discussions with the inspection and maintenance departments on technical aspects such as spectrum data and fault analysis, refines the records related to aircraft operations and the requirements for visual management, and implements joint inspections on a daily basis by the operation teams and maintenance teams, weekly by the mechanical, electrical, and instrumentation maintenance units and the respective regional teams, and monthly by the mechanical, electrical, and instrumentation operation and maintenance center along with the Refining Operations Department 3. This approach helps to identify and resolve issues promptly, effectively reducing the failure rate of rotating equipment and improving the quality of equipment maintenance. 　　The company also emphasizes the implementation of cadre-assisted inspections, regular inspections carried out by professional technical personnel at designated locations, as well as thorough daily inspections, careful monitoring, and precise operations by those on duty. It adopts the \"five essentials\" approach for emergency drills. Since the beginning of this year, the two atmospheric and vacuum distillation units have carried out 24 team-level emergency drills and 1 regional-level emergency drill, successfully handling 2 leakage incidents caused by equipment corrosion.