[Haichuan Chemical News] The domestication upgrade of low-nitrogen burners for ethylene cracking furnaces at Tianjin Petrochemical has been a complete success

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Following the initial success, in which all 6 cracking furnaces in Tianjin Petrochemical’s olefins division operated continuously for 6 months under normal operating conditions with nitrogen oxide emissions remaining stable between 56.3 and 80.6 milligrams per cubic meter, further optimization efforts have now led to emissions levels of 53.6 to 79.8 milligrams per cubic meter under coking conditions. This achievement makes Tianjin Petrochemical the first company in China to successfully implement domestic low-nitrogen burners to control nitrogen oxide emissions across the entire process, representing yet another significant milestone in the company’s efforts toward sustainable development. In recent years, Tianjin Petrochemical Company has actively responded to the calls for environmental protection and pollution control, energy conservation and emission reduction, as well as the development of a circular economy. It has fulfilled its responsibilities as a central state-owned enterprise by continuously increasing investment in environmental protection and energy-saving measures and carrying out related renovations. To meet the requirements of the \"Emission Standards for Pollutants in the Petrochemical Industry\" and comply with the environmental regulation requiring that the nitrogen oxide content in the flue gases from cracking furnaces be kept below 100 milligrams per cubic meter as of July 1, 2017, the Olefins Department of Tianjin Petrochemicals started working on the project to reduce nitrogen oxide emissions back in September last year, taking advantage of the regular maintenance period for the equipment. Among them, Reactor No. 1 is one of the units that underwent the initial set of modifications; by utilizing domestic manufacturing technologies, it was upgraded with a new type of low-nitrogen burner, thereby ensuring compliant emissions of nitrogen oxides. This renovation employs advanced low-nitrogen oxide combustion technologies such as staged fuel combustion, staged air distribution, and flue gas recirculation. It mainly involves modifying the burner components at the bottom of the pyrolyzer, including burner bricks, air boxes, air volume regulators, gas nozzles, and pilot lights, as well as the burner components on the side walls, such as burner bricks and support plates, gas injection nozzles, the housing, and air volume regulators. Low-nitrogen combustion is achieved by reducing the peak flame temperature of the burner, thereby effectively lowering the emissions of nitrogen oxides in the flue gases and helping to reduce air pollution. Since the operating temperature of a pyrolysis furnace is higher than that of a conventional heating furnace, reaching around 1200 degrees, nitrogen oxides are easily generated under such conditions, making it difficult to control their emissions. Not only was there no precedent for successfully using domestic low-nitrogen burners at that time to keep nitrogen oxide emissions under 90 milligrams per cubic meter, but there were also no successful cases of adopting foreign technology. To ensure the early and stable operation of the project and to meet the environmental protection approval requirements, after the renovation of Unit 1, the Olefins Department carried out thorough commissioning and testing of the burners. They assigned specialized personnel to work with the equipment manufacturers on-site to carry out adjustments and tests, while continuously monitoring parameters such as nitrogen oxide and carbon monoxide emissions. Closely monitor the changes in the main operating parameters of the pyrolyzer, collect data, and analyze the trends in the variations of these key parameters. Meanwhile, the operators continuously adjusted the heating ratio between bottom and side combustion in the pyrolysis furnace, and modified the specifications of the burner nozzles, the opening sizes, the orientation of the openings, as well as the precision of their fabrication and installation, thereby achieving continuous optimization of the renovation project. Not only that, but they also held numerous specialized meetings for technical discussions, gradually identifying the appropriate operating methods and heat supply ratios for pyrolyzing raw materials of different types in this furnace. As a result, the nitrogen oxide emissions from the pyrolysis furnace became increasingly stable, until long-term stable operation was achieved. In February this year, the Tianjin Environmental Protection Bureau conducted rigorous tests on the project that involved using low-nitrogen burners in Reactor No. 1 to control nitrogen oxide emissions. The feedstock used for these tests was light hydrocarbons, with production loads of 14 tons and 15 tons respectively. Two sets of data were collected at each load level, with an interval of one hour between each set of data, and the project successfully passed the environmental inspection. In June, the Olefins Department completed the retrofitting of low-nitrogen burners in all 6 cracking units. Following inspections by Tianjin’s environmental protection authorities, it was found that under normal operating conditions, the nitrogen oxide emission levels for all cracking units were between 56.3 and 80.6 milligrams per cubic meter, which is below the **standard of 100 milligrams per cubic meter. This represents a 50% reduction compared to the average emission level of 160 milligrams per cubic meter prior to the retrofitting. Building on the achievements made in the phased upgrades, the department continued to work on optimizing emission control under charring conditions and achieved success. (Li Jianzhong, Cao Yansen)