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**Overview of Dengfeng China Resources Power Co., Ltd. Boiler System and NOx Emission Control**
Dengfeng China Resources Power Co., Ltd. operates two 320MW boiler units, which are subcritical pressure, four-corner tangential firing boilers with natural oil-burning burners. Each boiler features 20 primary air nozzles arranged in five layers and 12 oil burners organized in three layers. The coal milling system consists of four steel ball mills, operating under negative pressure with intermediate storage. The furnace design includes a ring steam drum, single furnace, one intermediate reheat, balanced ventilation, solid slag discharge, and a fully steel-framed suspension structure with a "âˆ" type semi-open island layout. The boiler is designed based on the B-ECR parameter, with a rated evaporation of 900t/h at 300MW electrical load and a maximum continuous evaporation of 1025t/h at 330MW.
The pulverized coal burners are DC fixed horizontal concentrated flame burners, except for the B layer of #1 and #2 furnaces, where a center-expanded recirculation zone is used. Despite the lack of a perfect technology for reducing nitrogen oxides (NOx), it remains a critical environmental concern. NOx contributes significantly to acid rain and photochemical smog, posing serious threats to human health and the environment. As China's power industry expands, NOx emissions have become an increasingly important issue.
Since its establishment, Dengfeng China Resources Power Co., Ltd. has prioritized energy efficiency and environmental protection, continuously upgrading its facilities to reduce pollution and enhance social benefits. Key areas of focus include low-nitrogen burners, NOx control, and advanced combustion technologies.
**Coal Characteristics and Current NOx Levels**
The boiler currently uses medium to low calorific value, medium volatile, high ash, medium moisture, low sulfur, and lean coal. These characteristics influence combustion performance and emissions. Under a 250MW load, NOx levels in the flue gas reach approximately 1073/1055 mg/m³, while at 287MW, they remain around 1022/1021 mg/m³—indicating that reducing NOx remains a significant challenge.
**Burner Design and Optimization**
Design calculations were performed for both the base coal and verification coal types. The burner design was optimized to improve ignition, combustion efficiency, and reduce NOx emissions. A primary air and pulverized coal concentrator was introduced to ensure uniform airflow, high coal concentration, and reduced wear. This system also incorporates cooling perimeter winds and structural adjustments to delay mixing between primary and secondary air, thus minimizing NOx formation.
**Trace Oil Burner and Secondary Air System**
To enhance boiler start-up and operation, the B-layer burners of #2 boiler were upgraded to a new generation of trace oil direct ignition burners. The secondary air nozzles were redesigned to delay mixing and reduce NOx generation. Additionally, a high-level burnout system was implemented to distribute secondary air along the vertical direction of the furnace, improving combustion efficiency and reducing slag buildup.
**Conclusion and Future Work**
By implementing low-nitrogen burners and optimizing damper settings, the plant has successfully reduced NOx emissions and improved thermal efficiency. This approach not only lowers operational costs but also supports sustainable development. However, further research and optimization are needed to refine combustion processes and achieve even better results. Due to time and resource constraints, this study acknowledges certain limitations but emphasizes the importance of continued improvement in boiler operation and environmental protection.
Keywords: low-nitrogen burners, NOx reduction, environmental protection, pulverized coal combustion, boiler optimization