【Haichuan’s Best Practices】Online cleaning of the feed heat exchanger in continuous reforming units to ensure stable operation of the plants

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As of June 20, the feed heat exchanger of Daqing Petrochemical’s 1.2 million tons per year continuous reforming unit has been operating stably for one month following online cleaning operations. This is the first time such a thing has occurred in the refining and chemical enterprises of the group company; it provides technical references and practical experience for the online maintenance of key equipment in these facilities. It helps to eliminate the safety risks, losses in efficiency, and fluctuations in operational conditions that arise from traditional maintenance shutdowns, thereby enabling the facilities to operate more efficiently. Li Jianfeng, a third-level process engineer at the Second Refining Department, explained that the feed heat exchanger, a key piece of equipment in the continuous reforming unit, had become clogged due to scaling resulting from long-term operation; this caused the system pressure difference to increase continuously, forcing the unit to stop operating for maintenance. The technical team broke away from conventional cleaning approaches and proposed using a \"cooling, liquefaction, and dissolution\" method to reduce the temperature of the gas-phase reforming products from 480 degrees Celsius to a liquid state, thereby utilizing the aromatic components to dissolve the blockages. This online cleaning process was not only a technological breakthrough but also a comprehensive test of the team’s collaborative capabilities. The Production and Operation Department and the Planning and Operations Department of Daqing Petrochemical actively coordinate hydrogen balance and load adjustment across upstream and downstream units ； The Second Refining Department conducted multiple rounds of tabletop simulations for the operation process, identifying potential risks in terms of safety, environmental protection, and process efficiency, and formulating detailed preventive and control measures. During the cleaning process, Daqing Petrochemical established a comprehensive monitoring system: surveillance cameras transmit high-definition images in real time, optical gas imaging devices scan over 70 flanges prone to leakage every 2 hours, and drones are used to inspect heat sources in high-altitude areas. Meanwhile, technicians in the plant area regularly conduct stress tests on 41 key hangers, while operators closely monitor process parameters such as reaction temperature, hydrogen flow rate, and heat exchanger pressure differences to ensure the stable quality of products like gasoline, benzene, and toluene. “This online operation enabled efficient cleaning of the equipment, ensuring stable production of the plant with all parameters meeting the required standards. Next, we will establish technical standards and procedural specifications to provide a replicable model for the maintenance of similar installations. ”Li Jianfeng said.